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Message-ID: <CAF9_jYSrvBBenPqmo5-qokzDMJqYk7S5_-iFTYgKwAeRyZAp8g@mail.gmail.com>
Date:   Wed, 6 Sep 2023 18:27:08 +0200
From:   Paweł Anikiel <pan@...ihalf.com>
To:     Hans Verkuil <hverkuil@...all.nl>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, dinguyen@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, mchehab@...nel.org, upstream@...ihalf.com,
        amstan@...omium.org, ribalda@...omium.org
Subject: Re: [RFC PATCH 2/3] media: Add Google Chameleon v3 video driver

On Wed, Sep 6, 2023 at 1:15 PM Hans Verkuil <hverkuil@...all.nl> wrote:
>
> On 30/06/2023 16:40, Paweł Anikiel wrote:
> > Add driver for the video system present on the Chameleon v3. It
> > consists of two Intel DisplayPort DPRX IP cores and six video
> > interfaces (here called "framebuffers").
> >
> > Signed-off-by: Paweł Anikiel <pan@...ihalf.com>
> > ---
> >  drivers/media/platform/Kconfig                |   1 +
> >  drivers/media/platform/Makefile               |   1 +
> >  drivers/media/platform/google/Kconfig         |   4 +
> >  drivers/media/platform/google/Makefile        |   2 +
> >  .../media/platform/google/chameleonv3/Kconfig |   9 +
> >  .../platform/google/chameleonv3/Makefile      |  15 +
> >  .../platform/google/chameleonv3/chv3-core.c   | 292 ++++++++++
> >  .../platform/google/chameleonv3/chv3-core.h   |  17 +
> >  .../platform/google/chameleonv3/chv3-fb.c     | 539 ++++++++++++++++++
> >  .../platform/google/chameleonv3/chv3-fb.h     |  34 ++
> >  .../platform/google/chameleonv3/dprx-aux.c    |  77 +++
> >  .../platform/google/chameleonv3/dprx-dp.c     |  82 +++
> >  .../platform/google/chameleonv3/dprx-dpcd.c   | 424 ++++++++++++++
> >  .../platform/google/chameleonv3/dprx-dprx.c   | 262 +++++++++
> >  .../platform/google/chameleonv3/dprx-edid.c   |  39 ++
> >  .../platform/google/chameleonv3/dprx-i2c.c    |  41 ++
> >  .../platform/google/chameleonv3/dprx-mt.c     | 184 ++++++
> >  .../platform/google/chameleonv3/dprx-sbmsg.c  | 162 ++++++
> >  .../media/platform/google/chameleonv3/dprx.h  | 128 +++++
> >  19 files changed, 2313 insertions(+)
> >  create mode 100644 drivers/media/platform/google/Kconfig
> >  create mode 100644 drivers/media/platform/google/Makefile
> >  create mode 100644 drivers/media/platform/google/chameleonv3/Kconfig
> >  create mode 100644 drivers/media/platform/google/chameleonv3/Makefile
> >  create mode 100644 drivers/media/platform/google/chameleonv3/chv3-core.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/chv3-core.h
> >  create mode 100644 drivers/media/platform/google/chameleonv3/chv3-fb.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/chv3-fb.h
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-aux.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-dp.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-dpcd.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-dprx.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-edid.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-i2c.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-mt.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx-sbmsg.c
> >  create mode 100644 drivers/media/platform/google/chameleonv3/dprx.h
> >
> > diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> > index ee579916f874..2f15336cd25e 100644
> > --- a/drivers/media/platform/Kconfig
> > +++ b/drivers/media/platform/Kconfig
> > @@ -69,6 +69,7 @@ source "drivers/media/platform/aspeed/Kconfig"
> >  source "drivers/media/platform/atmel/Kconfig"
> >  source "drivers/media/platform/cadence/Kconfig"
> >  source "drivers/media/platform/chips-media/Kconfig"
> > +source "drivers/media/platform/google/Kconfig"
> >  source "drivers/media/platform/intel/Kconfig"
> >  source "drivers/media/platform/marvell/Kconfig"
> >  source "drivers/media/platform/mediatek/Kconfig"
> > diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> > index 5453bb868e67..db4a0fc7bfd3 100644
> > --- a/drivers/media/platform/Makefile
> > +++ b/drivers/media/platform/Makefile
> > @@ -12,6 +12,7 @@ obj-y += aspeed/
> >  obj-y += atmel/
> >  obj-y += cadence/
> >  obj-y += chips-media/
> > +obj-y += google/
> >  obj-y += intel/
> >  obj-y += marvell/
> >  obj-y += mediatek/
> > diff --git a/drivers/media/platform/google/Kconfig b/drivers/media/platform/google/Kconfig
> > new file mode 100644
> > index 000000000000..8dd3a955bef8
> > --- /dev/null
> > +++ b/drivers/media/platform/google/Kconfig
> > @@ -0,0 +1,4 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +
> > +source "drivers/media/platform/google/chameleonv3/Kconfig"
> > +
> > diff --git a/drivers/media/platform/google/Makefile b/drivers/media/platform/google/Makefile
> > new file mode 100644
> > index 000000000000..c971a09faeb4
> > --- /dev/null
> > +++ b/drivers/media/platform/google/Makefile
> > @@ -0,0 +1,2 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +obj-y += chameleonv3/
> > diff --git a/drivers/media/platform/google/chameleonv3/Kconfig b/drivers/media/platform/google/chameleonv3/Kconfig
> > new file mode 100644
> > index 000000000000..ef5130843301
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/Kconfig
> > @@ -0,0 +1,9 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +
> > +config VIDEO_CHAMELEONV3
> > +     tristate "Google Chameleon v3 video system driver"
> > +     depends on V4L_PLATFORM_DRIVERS
> > +     depends on VIDEO_DEV
> > +     select VIDEOBUF2_DMA_CONTIG
> > +     help
> > +       Enable support for the Google Chameleon v3 video system driver.
>
> This help text could use a bit more work...
>
> > diff --git a/drivers/media/platform/google/chameleonv3/Makefile b/drivers/media/platform/google/chameleonv3/Makefile
> > new file mode 100644
> > index 000000000000..d65e3c392127
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/Makefile
> > @@ -0,0 +1,15 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +
> > +chv3-video-objs := \
> > +     chv3-core.o \
> > +     chv3-fb.o \
> > +     dprx-aux.o \
> > +     dprx-dp.o \
> > +     dprx-dpcd.o \
> > +     dprx-dprx.o \
> > +     dprx-edid.o \
> > +     dprx-i2c.o \
> > +     dprx-mt.o \
> > +     dprx-sbmsg.o
> > +
> > +obj-$(CONFIG_VIDEO_CHAMELEONV3) += chv3-video.o
> > diff --git a/drivers/media/platform/google/chameleonv3/chv3-core.c b/drivers/media/platform/google/chameleonv3/chv3-core.c
> > new file mode 100644
> > index 000000000000..b571c0afb8bd
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/chv3-core.c
> > @@ -0,0 +1,292 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Driver for Chameleon v3 framebuffer
> > + *
> > + * Copyright 2022 Google LLC.
>
> 2023? Or 2022-2023?

Yes, the latter one. I'll update it.

>
> > + */
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/of.h>
> > +
> > +#include <linux/dma-mapping.h>
> > +#include <linux/interrupt.h>
> > +
> > +#include <linux/videodev2.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-ioctl.h>
> > +#include <media/videobuf2-dma-contig.h>
> > +
> > +#include "chv3-core.h"
> > +
> > +#define MODULE_NAME "chv3-video"
>
> Hmm, that's a bit obscure. How about chameleonv3-video?

There's already a chv3-audio driver upstream. Should I change this one anyway?

>
> > +
> > +static const struct chv3_fb_cfg fb0_cfg = {
> > +     .reg_core = "fb0",
> > +     .reg_irq = "fb0_irq",
> > +     .irq = "fb0",
> > +     .index = 0,
> > +};
> > +
> > +static const struct chv3_fb_cfg fb_mst_cfg[4] = {
> > +{
> > +     .reg_core = "fb_mst1",
> > +     .reg_irq = "fb_mst1_irq",
> > +     .irq = "fb_mst1",
> > +     .index = 1,
> > +},
> > +{
> > +     .reg_core = "fb_mst2",
> > +     .reg_irq = "fb_mst2_irq",
> > +     .irq = "fb_mst2",
> > +     .index = 2,
> > +},
> > +{
> > +     .reg_core = "fb_mst3",
> > +     .reg_irq = "fb_mst3_irq",
> > +     .irq = "fb_mst3",
> > +     .index = 3,
> > +},
> > +{
> > +     .reg_core = "fb_mst4",
> > +     .reg_irq = "fb_mst4_irq",
> > +     .irq = "fb_mst4",
> > +     .index = 4,
> > +},
> > +};
> > +
> > +static const struct chv3_fb_cfg fb_sst_cfg = {
> > +     .reg_core = "fb_sst",
> > +     .reg_irq = "fb_sst_irq",
> > +     .irq = "fb_sst",
> > +     .index = 5,
> > +};
> > +
> > +static const struct dprx_dp_cfg dp_mst_cfg = {
> > +     .reg_core = "dp_mst",
> > +     .reg_irq = "dp_mst_irq",
> > +     .irq = "dp_mst",
> > +     .has_mst = 1,
> > +     .sink_count = 4,
> > +};
> > +
> > +static const struct dprx_dp_cfg dp_sst_cfg = {
> > +     .reg_core = "dp_sst",
> > +     .reg_irq = "dp_sst_irq",
> > +     .irq = "dp_sst",
> > +     .has_mst = 0,
> > +     .sink_count = 1,
> > +};
> > +
> > +int chv3_g_edid(struct chv3_video *video, int index, struct v4l2_edid *edid)
> > +{
> > +     u32 end_block = edid->start_block + edid->blocks;
> > +     struct sink *sink;
> > +
> > +     if (index == 0 || index > 5)
>
> You should probably use a define instead of '5'.
>
> > +             return -ENOTTY;
> > +     if (edid->pad)
> > +             return -EINVAL;
> > +
> > +     if (1 <= index && index <= 4)
> > +             sink = &video->dp_mst.sinks[index-1];
> > +     else
> > +             sink = &video->dp_sst.sinks[0];
> > +
> > +     if (edid->start_block == 0 && edid->blocks == 0) {
> > +             edid->blocks = sink->blocks;
> > +             return 0;
> > +     }
> > +
> > +     if (edid->start_block > sink->blocks)
> > +             return -EINVAL;
> > +     if (end_block > sink->blocks) {
> > +             end_block = sink->blocks;
> > +             edid->blocks = end_block - edid->start_block;
> > +     }
> > +
> > +     memcpy(edid->edid, sink->edid + edid->start_block * 128, edid->blocks * 128);
> > +
> > +     return 0;
> > +}
> > +
> > +int chv3_s_edid(struct chv3_video *video, int index, struct v4l2_edid *edid)
> > +{
> > +     struct sink *sink;
> > +
> > +     if (index == 0 || index > 5)
> > +             return -ENOTTY;
> > +     if (edid->pad)
> > +             return -EINVAL;
> > +
> > +     if (1 <= index && index <= 4)
> > +             sink = &video->dp_mst.sinks[index-1];
> > +     else
> > +             sink = &video->dp_sst.sinks[0];
> > +
> > +     if (edid->start_block != 0)
> > +             return -EINVAL;
> > +     if (edid->blocks > DPRX_MAX_EDID_BLOCKS) {
> > +             edid->blocks = DPRX_MAX_EDID_BLOCKS;
> > +             return -E2BIG;
> > +     }
> > +
> > +     sink->blocks = edid->blocks;
> > +     memcpy(sink->edid, edid->edid, edid->blocks * 128);
> > +
> > +     return 0;
> > +}
> > +
> > +
> > +static ssize_t dp_hpd_show(struct device *dev, struct device_attribute *attr,
> > +                        char *buf);
> > +static ssize_t dp_hpd_store(struct device *dev, struct device_attribute *attr,
> > +                         const char *buf, size_t count);
> > +
> > +static struct device_attribute dev_attr_dp0_hpd = {
> > +     .attr = { .name = "hpd", .mode = 0644 },
> > +     .show = dp_hpd_show,
> > +     .store = dp_hpd_store,
> > +};
> > +
> > +static struct device_attribute dev_attr_dp1_hpd = {
> > +     .attr = { .name = "hpd", .mode = 0644 },
> > +     .show = dp_hpd_show,
> > +     .store = dp_hpd_store,
> > +};
> > +
> > +static struct attribute *dp0_attrs[] = {
> > +     &dev_attr_dp0_hpd.attr,
> > +     NULL,
> > +};
> > +
> > +static struct attribute *dp1_attrs[] = {
> > +     &dev_attr_dp1_hpd.attr,
> > +     NULL,
> > +};
> > +
> > +static struct attribute_group dp0_attr_group = {
> > +     .name = "dp0",
> > +     .attrs = dp0_attrs,
> > +};
> > +
> > +static struct attribute_group dp1_attr_group = {
> > +     .name = "dp1",
> > +     .attrs = dp1_attrs,
> > +};
> > +
> > +static ssize_t dp_hpd_show(struct device *dev, struct device_attribute *attr,
> > +                        char *buf)
> > +{
> > +     struct chv3_video *video = dev_get_drvdata(dev);
> > +     struct dprx_dp *dp;
> > +
> > +     if (attr == &dev_attr_dp0_hpd)
> > +             dp = &video->dp_mst;
> > +     else
> > +             dp = &video->dp_sst;
> > +
> > +     return sprintf(buf, "%d\n", dprx_dprx_get_hpd(dp));
> > +}
> > +
> > +static ssize_t dp_hpd_store(struct device *dev, struct device_attribute *attr,
> > +                         const char *buf, size_t count)
> > +{
> > +     struct chv3_video *video = dev_get_drvdata(dev);
> > +     struct dprx_dp *dp;
> > +     unsigned long val;
> > +     int res;
> > +
> > +     if (attr == &dev_attr_dp0_hpd)
> > +             dp = &video->dp_mst;
> > +     else
> > +             dp = &video->dp_sst;
> > +
> > +     res = kstrtoul(buf, 10, &val);
> > +     if (res)
> > +             return res;
> > +
> > +     dprx_dprx_set_hpd(dp, val);
> > +     return count;
> > +}
>
> My guess is that this is added to allow userspace to toggle the HPD when it
> sets the EDID. But this is something the s_edid should do. Typically it will
> pull the HPD low, then update the EDID and start delayed work to pull the HPD
> high again after 100ms.
>
> You might still want to keep this to do debugging, but you don't need this
> for dealing with EDID changes, the driver should take care of that.

Thanks for the explanation, I'll add it to s_edid.

>
> > +
> > +static int chv3_video_probe(struct platform_device *pdev)
> > +{
> > +     struct chv3_video *video;
> > +     int res;
> > +     int i;
> > +
> > +     video = devm_kzalloc(&pdev->dev, sizeof(*video), GFP_KERNEL);
> > +     if (!video)
> > +             return -ENOMEM;
> > +     video->dev = &pdev->dev;
> > +     platform_set_drvdata(pdev, video);
> > +
> > +     /* register v4l2_device */
> > +     res = v4l2_device_register(video->dev, &video->v4l2_dev);
> > +     if (res)
> > +             return res;
> > +
> > +     /* initialize fb devices */
> > +     res = chv3_fb_register(&video->fb0, video, &fb0_cfg);
> > +     if (res)
> > +             return res;
> > +
> > +     for (i = 0; i < 4; i++) {
> > +             res = chv3_fb_register(&video->fb_mst[i], video, &fb_mst_cfg[i]);
> > +             if (res)
> > +                     return res;
> > +     }
> > +
> > +     res = chv3_fb_register(&video->fb_sst, video, &fb_sst_cfg);
> > +     if (res)
> > +             return res;
> > +
> > +     /* initialize dp devices */
> > +     res = dprx_dp_init(&video->dp_mst, video->dev, &dp_mst_cfg);
> > +     if (res)
> > +             return res;
> > +
> > +     res = dprx_dp_init(&video->dp_sst, video->dev, &dp_sst_cfg);
> > +     if (res)
> > +             return res;
> > +
> > +     /* create sysfs files */
> > +     res = sysfs_create_group(&video->dev->kobj, &dp0_attr_group);
> > +     if (res)
> > +             return res;
> > +
> > +     res = sysfs_create_group(&video->dev->kobj, &dp1_attr_group);
> > +     if (res)
> > +             return res;
> > +
> > +     return 0;
> > +}
> > +
> > +static int chv3_video_remove(struct platform_device *pdev)
> > +{
> > +     struct chv3_video *video = platform_get_drvdata(pdev);
> > +
> > +     v4l2_device_unregister(&video->v4l2_dev);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct of_device_id chv3_video_match_table[] = {
> > +     { .compatible = "google,chv3-video" },
>
> I would lean towards writing "google,chameleonv3-video" here as well.

As above, there's already a google,chv3-audio binding.

>
> > +     { },
> > +};
> > +
> > +static struct platform_driver chv3_video_platform_driver = {
> > +     .probe = chv3_video_probe,
> > +     .remove = chv3_video_remove,
> > +     .driver = {
> > +             .name = MODULE_NAME,
> > +             .of_match_table = chv3_video_match_table,
> > +     },
> > +};
> > +
> > +module_platform_driver(chv3_video_platform_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > +
> > diff --git a/drivers/media/platform/google/chameleonv3/chv3-core.h b/drivers/media/platform/google/chameleonv3/chv3-core.h
> > new file mode 100644
> > index 000000000000..9a435cba25bd
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/chv3-core.h
> > @@ -0,0 +1,17 @@
> > +#include "chv3-fb.h"
> > +#include "dprx.h"
> > +
> > +struct chv3_video {
> > +     struct device *dev;
> > +     struct v4l2_device v4l2_dev;
> > +
> > +     struct chv3_fb fb0;
> > +     struct chv3_fb fb_mst[4];
> > +     struct chv3_fb fb_sst;
> > +
> > +     struct dprx_dp dp_mst;
> > +     struct dprx_dp dp_sst;
> > +};
> > +
> > +int chv3_g_edid(struct chv3_video *video, int index, struct v4l2_edid *edid);
> > +int chv3_s_edid(struct chv3_video *video, int index, struct v4l2_edid *edid);
> > diff --git a/drivers/media/platform/google/chameleonv3/chv3-fb.c b/drivers/media/platform/google/chameleonv3/chv3-fb.c
> > new file mode 100644
> > index 000000000000..a9b97d637ed5
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/chv3-fb.c
> > @@ -0,0 +1,539 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Driver for Chameleon v3 framebuffer
> > + *
> > + * Copyright 2022 Google LLC.
> > + */
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/of.h>
> > +
> > +#include <linux/delay.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/interrupt.h>
> > +
> > +#include <linux/videodev2.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-ioctl.h>
> > +#include <media/videobuf2-dma-contig.h>
> > +
> > +#include "chv3-core.h"
> > +
> > +#define MODULE_NAME  "chv3-fb"
> > +
> > +#define FB_EN                0x00
> > +#define FB_HEIGHT    0x04
> > +#define FB_WIDTH     0x08
> > +#define FB_BUFFERA   0x0c
> > +#define FB_BUFFERB   0x10
> > +#define FB_BUFFERSIZE        0x14
> > +#define FB_RESET     0x18
> > +#define FB_ERRORSTATUS       0x1c
> > +#define FB_IOCOLOR   0x20
> > +#define FB_IODATARATE        0x24
> > +#define FB_IOPIXELMODE       0x28
> > +#define FB_SYNCPOLARITY      0x2c
> > +#define FB_DMAFORMAT 0x30
> > +#define FB_VERSION   0x34
> > +#define FB_VERSION_CURRENT   0xc0fb0001
> > +#define FB_IRQ_MASK  0x8
> > +#define FB_IRQ_CLR   0xc
> > +#define FB_IRQ_ALL   0xf
> > +#define FB_IRQ_BUFF0         (1 << 0)
> > +#define FB_IRQ_BUFF1         (1 << 1)
> > +#define FB_IRQ_RESOLUTION    (1 << 2)
> > +#define FB_IRQ_ERROR         (1 << 3)
> > +
> > +struct chv3_fb_buffer {
> > +     struct vb2_v4l2_buffer vb;
> > +     struct list_head link;
> > +};
> > +
> > +struct chv3_dma_format {
> > +     u32 id;
> > +     u32 pixfmt;
> > +     int bpp;
> > +};
> > +
> > +struct chv3_dma_format chv3_dma_formats[] = {
> > +     { 0, V4L2_PIX_FMT_RGB24 , 3 },
> > +     { 1, V4L2_PIX_FMT_RGB30U, 6 },
> > +     { 2, V4L2_PIX_FMT_RGB30L, 6 },
> > +     { 3, V4L2_PIX_FMT_RGB36U, 6 },
> > +     { 4, V4L2_PIX_FMT_RGB36L, 6 },
> > +     { 5, V4L2_PIX_FMT_RGB48 , 6 },
> > +     { 7, V4L2_PIX_FMT_BGRX32, 4 },
> > +};
> > +
> > +static void fb_set_dma_format(struct chv3_fb *fb, struct chv3_dma_format *dmaf)
> > +{
> > +     writel(dmaf->id, fb->iobase + FB_DMAFORMAT);
> > +     /* we need to wait one frame for the width/height to update */
> > +     mdelay(50);
> > +     fb->fmt.width  = readl(fb->iobase + FB_WIDTH);
> > +     fb->fmt.height = readl(fb->iobase + FB_HEIGHT);
> > +
> > +     fb->fmt.pixelformat = dmaf->pixfmt;
> > +     fb->fmt.field = V4L2_FIELD_NONE;
> > +     fb->fmt.bytesperline = fb->fmt.width * dmaf->bpp;
> > +     fb->fmt.sizeimage = fb->fmt.bytesperline * fb->fmt.height;
> > +     fb->fmt.colorspace = V4L2_COLORSPACE_SRGB;
> > +
> > +     writel(fb->fmt.sizeimage, fb->iobase + FB_BUFFERSIZE);
> > +}
> > +
> > +/* v4l2 ioctls */
> > +
> > +static int vidioc_querycap(struct file *file, void *data,
> > +                        struct v4l2_capability *cap)
> > +{
> > +     strscpy(cap->driver, MODULE_NAME, sizeof(cap->driver));
> > +     strscpy(cap->card, "Chameleonv3 framebuffer", sizeof(cap->card));
> > +     snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> > +              MODULE_NAME);
>
> bus_info is set automatically for platform devices, so you can drop that.
>
> > +
> > +     return 0;
> > +}
> > +
> > +/*
> > + * We can't control the resolution, we can only read what it currently is from
> > + * the framebuffer. In order not to confuse the application, the resolution is
> > + * saved in fb->fmt, and is only updated when the application calls open() and
> > + * there are no other applications that have the file opened.
> > + */
>
> Why not use the DV_TIMINGS API?
> https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/dv-timings.html
>
> That's meant for e.g. HDMI capture where the resolution can change. It seems much
> more appropriate for this.

I have a few questions:
1. Could you clarify how this API helps with resolution changes? I
couldn't find anything in the docs about this. When looking at drivers
using DV_TIMINGS, they send a V4L2_EVENT_SOURCE_CHANGE event when a
resolution change happens, which is a different API if I understand
correctly.
2. How should the S_DV_TIMINGS ioctls be handled if the timings can't
be changed? In the intel DPRX IP, the timings are only available as
read-only MSA registers:
https://www.intel.com/content/www/us/en/docs/programmable/683273/23-1-20-0-1/sink-msa-registers.html
3. The G_FMT ioctl still needs to be handled. Is my approach of
delaying the resolution change appropriate?

>
> > +
> > +static int vidioc_g_fmt_vid_cap(struct file *file, void *data,
> > +                             struct v4l2_format *fmt)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +
> > +     fmt->fmt.pix = fb->fmt;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_s_fmt_vid_cap(struct file *file, void *data,
> > +                             struct v4l2_format *fmt)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +
> > +     if (fmt->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
> > +             struct chv3_dma_format *dmaf;
> > +
> > +             for (dmaf = chv3_dma_formats; dmaf < &chv3_dma_formats[ARRAY_SIZE(chv3_dma_formats)]; dmaf++) {
> > +                     if (dmaf->pixfmt == fmt->fmt.pix.pixelformat) {
> > +                             fb_set_dma_format(fb, dmaf);
> > +                             break;
> > +                     }
> > +             }
> > +     }
> > +
> > +     fmt->fmt.pix = fb->fmt;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_enum_fmt_vid_cap(struct file *file, void *data,
> > +                                struct v4l2_fmtdesc *fmt)
> > +{
> > +     if (fmt->index >= ARRAY_SIZE(chv3_dma_formats))
> > +             return -EINVAL;
> > +     fmt->flags = 0;
> > +     fmt->pixelformat = chv3_dma_formats[fmt->index].pixfmt;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_enum_framesizes(struct file *file, void *data,
> > +                               struct v4l2_frmsizeenum *frm)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +     struct chv3_dma_format *dmaf;
> > +     bool fmt_ok = false;
> > +
> > +     if (frm->index != 0)
> > +             return -EINVAL;
> > +
> > +     for (dmaf = chv3_dma_formats; dmaf < &chv3_dma_formats[ARRAY_SIZE(chv3_dma_formats)]; dmaf++) {
> > +             if (dmaf->pixfmt == frm->pixel_format) {
> > +                     fmt_ok = true;
> > +                     break;
> > +             }
> > +     }
> > +     if (!fmt_ok)
> > +             return -EINVAL;
> > +
> > +     frm->type = V4L2_FRMSIZE_TYPE_DISCRETE;
> > +     frm->discrete.width  = fb->fmt.width;
> > +     frm->discrete.height = fb->fmt.height;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_g_input(struct file *file, void *data, unsigned int *index)
> > +{
> > +     *index = 0;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_s_input(struct file *file, void *data, unsigned int index)
> > +{
> > +     if (index != 0)
> > +             return -EINVAL;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_enum_input(struct file *file, void *data,
> > +                          struct v4l2_input *input)
> > +{
> > +     if (input->index != 0)
> > +             return -EINVAL;
> > +     strcpy(input->name, "input0");
> > +     input->type = V4L2_INPUT_TYPE_CAMERA;
> > +     return 0;
> > +}
> > +
> > +static int vidioc_g_edid(struct file *file, void *data,
> > +                      struct v4l2_edid *edid)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +
> > +     return chv3_g_edid(fb->parent, fb->index, edid);
> > +}
> > +
> > +static int vidioc_s_edid(struct file *file, void *data,
> > +                      struct v4l2_edid *edid)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +
> > +     return chv3_s_edid(fb->parent, fb->index, edid);
> > +}
> > +
> > +static const struct v4l2_ioctl_ops fb_v4l2_ioctl_ops = {
> > +     .vidioc_querycap = vidioc_querycap,
> > +
> > +     .vidioc_enum_fmt_vid_cap = vidioc_enum_fmt_vid_cap,
> > +     .vidioc_g_fmt_vid_cap = vidioc_g_fmt_vid_cap,
> > +     .vidioc_s_fmt_vid_cap = vidioc_s_fmt_vid_cap,
> > +     .vidioc_try_fmt_vid_cap = vidioc_g_fmt_vid_cap,
> > +
> > +     .vidioc_enum_framesizes = vidioc_enum_framesizes,
> > +
> > +     .vidioc_enum_input = vidioc_enum_input,
> > +     .vidioc_g_input = vidioc_g_input,
> > +     .vidioc_s_input = vidioc_s_input,
> > +     .vidioc_g_edid = vidioc_g_edid,
> > +     .vidioc_s_edid = vidioc_s_edid,
> > +
> > +     .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > +     .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > +     .vidioc_querybuf = vb2_ioctl_querybuf,
>
> Add prepare_buf and expbuf as well. No need to leave those out.
>
> > +     .vidioc_qbuf = vb2_ioctl_qbuf,
> > +     .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > +     .vidioc_streamon = vb2_ioctl_streamon,
> > +     .vidioc_streamoff = vb2_ioctl_streamoff,
> > +};
> > +
> > +/* videobuf2 operations */
> > +
> > +static int fb_queue_setup(struct vb2_queue *q,
> > +                    unsigned int *nbuffers, unsigned int *nplanes,
> > +                    unsigned int sizes[], struct device *alloc_devs[])
> > +{
> > +     struct chv3_fb *fb = vb2_get_drv_priv(q);
> > +
> > +     if (!fb->fmt.sizeimage)
> > +             return -EIO;
>
> Hmm, V4L2 expects that there is always a valid video format, so this should
> never happen. If it doesn't know the correct video format (typical for e.g.
> HDMI/DP inputs), then it just defaults to something reasonable (1920x1080 or so).
>
> > +
> > +     if (*nplanes) {
> > +             if (sizes[0] < fb->fmt.sizeimage)
> > +                     return -EINVAL;
> > +             return 0;
> > +     }
> > +     *nplanes = 1;
> > +     sizes[0] = fb->fmt.sizeimage;
> > +     return 0;
> > +}
> > +
> > +/*
> > + * There are two address registers: BUFFERA and BUFFERB. The framebuffer
> > + * alternates writing between them (i.e. even frames go to BUFFERA, odd
> > + * ones to BUFFERB).
> > + *
> > + *  (buffer queue) >     QUEUED ---> QUEUED ---> QUEUED ---> ...
> > + *                       BUFFERA     BUFFERB
> > + *  (hw writing to this) ^
> > + *                (and then to this) ^
> > + *
> > + * The buffer swapping happens at irq time. When an irq comes, the next
> > + * frame is already assigned an address in the buffer queue. This gives
> > + * the irq handler a whole frame's worth of time to update the buffer
> > + * address register.
> > + */
> > +
> > +static dma_addr_t fb_buffer_dma_addr(struct chv3_fb_buffer *buf)
> > +{
> > +     return vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> > +}
> > +
> > +static void fb_start_frame(struct chv3_fb *fb, struct chv3_fb_buffer *buf)
> > +{
> > +     fb->writing_to_a = 1;
> > +     writel(fb_buffer_dma_addr(buf), fb->iobase + FB_BUFFERA);
> > +     writel(1, fb->iobase + FB_EN);
> > +}
> > +
> > +static void fb_next_frame(struct chv3_fb *fb, struct chv3_fb_buffer *buf)
> > +{
> > +     u32 reg = fb->writing_to_a ? FB_BUFFERB : FB_BUFFERA;
> > +
> > +     writel(fb_buffer_dma_addr(buf), fb->iobase + reg);
> > +}
> > +
> > +static int fb_start_streaming(struct vb2_queue *q, unsigned int count)
> > +{
> > +     struct chv3_fb *fb = vb2_get_drv_priv(q);
> > +     struct chv3_fb_buffer *buf;
> > +     unsigned long flags;
> > +
> > +     fb->streaming = 1;
>
> You can let vb2_queue keep track of the streaming state: vb2_is_streaming(q).
>
> > +     fb->sequence = 0;
> > +
> > +     spin_lock_irqsave(&fb->bufs_lock, flags);
> > +     buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> > +     if (buf) {
> > +             fb_start_frame(fb, buf);
> > +             if (!list_is_last(&buf->link, &fb->bufs))
> > +                     fb_next_frame(fb, list_next_entry(buf, link));
> > +     }
> > +     spin_unlock_irqrestore(&fb->bufs_lock, flags);
> > +
> > +     return 0;
> > +}
> > +
> > +static void fb_stop_streaming(struct vb2_queue *q)
> > +{
> > +     struct chv3_fb *fb = vb2_get_drv_priv(q);
> > +     struct chv3_fb_buffer *buf;
> > +     unsigned long flags;
> > +
> > +     fb->streaming = 0;
> > +     writel(0, fb->iobase + FB_EN);
> > +
> > +     spin_lock_irqsave(&fb->bufs_lock, flags);
> > +     list_for_each_entry(buf, &fb->bufs, link)
> > +             vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> > +     INIT_LIST_HEAD(&fb->bufs);
> > +     spin_unlock_irqrestore(&fb->bufs_lock, flags);
> > +}
> > +
> > +static struct chv3_fb_buffer *to_chv3_fb_buffer(struct vb2_v4l2_buffer *b)
> > +{
> > +     return container_of(b, struct chv3_fb_buffer, vb);
> > +}
> > +
> > +static void fb_buf_queue(struct vb2_buffer *vb)
> > +{
> > +     struct chv3_fb *fb = vb2_get_drv_priv(vb->vb2_queue);
> > +     struct vb2_v4l2_buffer *v4l2_buf = to_vb2_v4l2_buffer(vb);
> > +     struct chv3_fb_buffer *buf = to_chv3_fb_buffer(v4l2_buf);
> > +     bool first, second;
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&fb->bufs_lock, flags);
> > +     first = list_empty(&fb->bufs);
> > +     second = list_is_singular(&fb->bufs);
> > +     list_add_tail(&buf->link, &fb->bufs);
> > +     if (fb->streaming) {
> > +             if (first)
> > +                     fb_start_frame(fb, buf);
> > +             else if (second)
> > +                     fb_next_frame(fb, buf);
> > +     }
> > +     spin_unlock_irqrestore(&fb->bufs_lock, flags);
> > +}
> > +
> > +static const struct vb2_ops fb_vb2_ops = {
> > +     .queue_setup = fb_queue_setup,
> > +     .wait_prepare = vb2_ops_wait_prepare,
> > +     .wait_finish = vb2_ops_wait_finish,
> > +     .start_streaming = fb_start_streaming,
> > +     .stop_streaming = fb_stop_streaming,
> > +     .buf_queue = fb_buf_queue,
> > +};
> > +
> > +/* file operations */
> > +
> > +static int fb_open(struct file *file)
> > +{
> > +     struct chv3_fb *fb = video_drvdata(file);
> > +     int res;
> > +
> > +     mutex_lock(&fb->fb_lock);
> > +     res = v4l2_fh_open(file);
> > +     if (!res) {
> > +             if (v4l2_fh_is_singular_file(file))
> > +                     fb_set_dma_format(fb, &chv3_dma_formats[0]);
> > +     }
> > +     mutex_unlock(&fb->fb_lock);
> > +
> > +     return res;
> > +}
> > +
> > +static const struct v4l2_file_operations fb_v4l2_fops = {
> > +     .owner = THIS_MODULE,
> > +     .open = fb_open,
> > +     .release = vb2_fop_release,
> > +     .unlocked_ioctl = video_ioctl2,
> > +     .mmap = vb2_fop_mmap,
> > +     .poll = vb2_fop_poll,
> > +};
> > +
> > +/* irq handling */
> > +
> > +static void fb_frame_irq(struct chv3_fb *fb)
> > +{
> > +     struct chv3_fb_buffer *buf;
> > +
> > +     spin_lock(&fb->bufs_lock);
> > +
> > +     buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> > +     if (!buf)
> > +             goto empty;
> > +     list_del(&buf->link);
> > +
> > +     vb2_set_plane_payload(&buf->vb.vb2_buf, 0, fb->fmt.sizeimage);
> > +     buf->vb.vb2_buf.timestamp = ktime_get_ns();
> > +     buf->vb.sequence = fb->sequence++;
> > +     buf->vb.field = V4L2_FIELD_NONE;
> > +     vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> > +
> > +     buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> > +     if (buf) {
> > +             fb->writing_to_a = !fb->writing_to_a;
> > +             if (!list_is_last(&buf->link, &fb->bufs))
> > +                     fb_next_frame(fb, list_next_entry(buf, link));
> > +     } else {
> > +             writel(0, fb->iobase + FB_EN);
> > +     }
> > +empty:
> > +     spin_unlock(&fb->bufs_lock);
> > +}
> > +
> > +static irqreturn_t fb_isr(int irq, void *data)
> > +{
> > +     struct chv3_fb *fb = data;
> > +     unsigned int reg;
> > +
> > +     reg = readl(fb->iobase_irq + FB_IRQ_CLR);
> > +     if (!reg)
> > +             return IRQ_NONE;
> > +
> > +     if (reg & (FB_IRQ_BUFF0 | FB_IRQ_BUFF1))
> > +             fb_frame_irq(fb);
> > +     if (reg & FB_IRQ_ERROR) {
> > +             dev_warn(fb->dev, "framebuffer error: 0x%x\n",
> > +                    readl(fb->iobase + FB_ERRORSTATUS));
> > +     }
> > +
> > +     writel(reg, fb->iobase_irq + FB_IRQ_CLR);
> > +
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +/* driver probe & remove */
> > +
> > +static int fb_check_version(struct chv3_fb *fb)
> > +{
> > +     u32 version;
> > +
> > +     version = readl(fb->iobase + FB_VERSION);
> > +     if (version != FB_VERSION_CURRENT) {
> > +             dev_warn(fb->dev,
> > +                      "wrong framebuffer version: expected %x, got %x\n",
> > +                      FB_VERSION_CURRENT, version);
> > +             return -1;
> > +     }
> > +     return 0;
> > +}
> > +
> > +int chv3_fb_register(struct chv3_fb *fb,
> > +                  struct chv3_video *video,
> > +                  const struct chv3_fb_cfg *cfg)
> > +{
> > +     struct platform_device *pdev = to_platform_device(video->dev);
> > +     int res;
> > +     int irq;
> > +
> > +     fb->dev = video->dev;
> > +     fb->parent = video;
> > +     fb->index = cfg->index;
> > +
> > +     /* map register space */
> > +     fb->iobase = devm_platform_ioremap_resource_byname(pdev, cfg->reg_core);
> > +     if (IS_ERR(fb->iobase))
> > +             return -ENOMEM;
> > +
> > +     fb->iobase_irq = devm_platform_ioremap_resource_byname(pdev, cfg->reg_irq);
> > +     if (IS_ERR(fb->iobase_irq))
> > +             return -ENOMEM;
> > +
> > +     /* check hw version */
> > +     if (fb_check_version(fb))
> > +             return -ENODEV;
> > +
> > +     /* setup interrupts */
> > +     irq = platform_get_irq_byname(pdev, cfg->irq);
> > +     if (irq < 0)
> > +             return -ENXIO;
> > +     res = devm_request_irq(fb->dev, irq, fb_isr, 0, cfg->irq, fb);
> > +     if (res)
> > +             return res;
> > +
> > +     /* setup dma */
> > +     dma_set_coherent_mask(fb->dev, DMA_BIT_MASK(32));
> > +
> > +     /* initialize vb2 queue */
> > +     fb->queue.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > +     fb->queue.io_modes = VB2_MMAP;
>
> I strongly suggest adding VB2_DMABUF.
>
> > +     fb->queue.dev = fb->dev;
> > +     fb->queue.lock = &fb->fb_lock;
> > +     fb->queue.ops = &fb_vb2_ops;
> > +     fb->queue.mem_ops = &vb2_dma_contig_memops;
> > +     fb->queue.drv_priv = fb;
> > +     fb->queue.buf_struct_size = sizeof(struct chv3_fb_buffer);
> > +     fb->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> > +     res = vb2_queue_init(&fb->queue);
> > +     if (res)
> > +             return res;
> > +
> > +     /* register video_device */
> > +     strcpy(fb->vdev.name, MODULE_NAME);
> > +     fb->vdev.fops = &fb_v4l2_fops;
> > +     fb->vdev.ioctl_ops = &fb_v4l2_ioctl_ops;
> > +     fb->vdev.lock = &fb->fb_lock;
> > +     fb->vdev.release = video_device_release_empty;
> > +     fb->vdev.device_caps =
> > +             V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> > +     fb->vdev.v4l2_dev = &video->v4l2_dev;
> > +     fb->vdev.queue = &fb->queue;
> > +     video_set_drvdata(&fb->vdev, fb);
> > +     res = video_register_device(&fb->vdev, VFL_TYPE_VIDEO, -1);
> > +     if (res)
> > +             return res;
> > +
> > +     /* initialize rest of driver struct */
> > +     INIT_LIST_HEAD(&fb->bufs);
> > +     spin_lock_init(&fb->bufs_lock);
> > +     mutex_init(&fb->fb_lock);
> > +
> > +     /* initialize hw */
> > +     writel(1, fb->iobase + FB_RESET);
> > +     writel(1, fb->iobase + FB_IODATARATE);
> > +     writel(1, fb->iobase + FB_IOPIXELMODE);
> > +     writel(FB_IRQ_BUFF0 | FB_IRQ_BUFF1 | FB_IRQ_ERROR, fb->iobase_irq + FB_IRQ_MASK);
> > +
> > +     return 0;
> > +}
> > +
> > +void chv3_fb_unregister(struct chv3_fb *fb)
> > +{
> > +     video_unregister_device(&fb->vdev);
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/chv3-fb.h b/drivers/media/platform/google/chameleonv3/chv3-fb.h
> > new file mode 100644
> > index 000000000000..2ece35a114df
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/chv3-fb.h
> > @@ -0,0 +1,34 @@
> > +struct chv3_fb {
> > +     struct device *dev;
> > +     void __iomem *iobase;
> > +     void __iomem *iobase_irq;
> > +     struct chv3_video *parent;
> > +     int index;
> > +
> > +     struct vb2_queue queue;
> > +     struct video_device vdev;
> > +     struct v4l2_pix_format fmt;
> > +
> > +     u32 sequence;
> > +     bool streaming;
> > +     bool writing_to_a;
> > +
> > +     struct list_head bufs;
> > +     spinlock_t bufs_lock;
> > +
> > +     struct mutex fb_lock;
> > +};
> > +
> > +struct chv3_fb_cfg {
> > +     const char *reg_core;
> > +     const char *reg_irq;
> > +     const char *irq;
> > +     int index;
> > +};
> > +
> > +int chv3_fb_register(struct chv3_fb *fb,
> > +                  struct chv3_video *video,
> > +                  const struct chv3_fb_cfg *cfg);
> > +
> > +
> > +void chv3_fb_unregister(struct chv3_fb *fb);
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-aux.c b/drivers/media/platform/google/chameleonv3/dprx-aux.c
> > new file mode 100644
> > index 000000000000..56d82c963b4b
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-aux.c
> > @@ -0,0 +1,77 @@
> > +#include <linux/string.h>
> > +
> > +#include "dprx.h"
> > +
> > +static void handle_i2c_read(struct dprx_dp *dp, struct aux_msg *req,
> > +                         struct aux_msg *res)
> > +{
> > +     int r;
> > +
> > +     r = dprx_i2c_read(&dp->sinks[0], req->addr, res->data, req->len);
> > +     if (!r) {
> > +             res->cmd = AUX_ACK;
> > +             res->len = req->len;
> > +     } else {
> > +             res->cmd = AUX_I2C_NACK;
> > +             res->len = 0;
> > +     }
> > +}
> > +
> > +static void handle_i2c_write(struct dprx_dp *dp, struct aux_msg *req,
> > +                          struct aux_msg *res)
> > +{
> > +     int r;
> > +
> > +     r = dprx_i2c_write(&dp->sinks[0], req->addr, req->data, req->len);
> > +     if (!r)
> > +             res->cmd = AUX_ACK;
> > +     else
> > +             res->cmd = AUX_I2C_NACK;
> > +     res->len = 0;
> > +}
> > +
> > +void dprx_aux_handle_request(struct dprx_dp *dp, struct aux_msg *req,
> > +                          struct aux_msg *res)
> > +{
> > +     if (req->cmd & 8) {
> > +             dprx_dpcd_access(dp, req, res);
> > +     } else {
> > +             if (req->cmd & 1)
> > +                     handle_i2c_read(dp, req, res);
> > +             else
> > +                     handle_i2c_write(dp, req, res);
> > +             if (!(req->cmd & 4))
> > +                     dp->sinks[0].segment = 0;
> > +     }
> > +}
> > +
> > +int dprx_aux_read_request(struct dprx_dp *dp, struct aux_msg *req)
> > +{
> > +     u8 data[20];
> > +     int len;
> > +
> > +     len = dprx_dprx_read_aux(dp, data);
> > +     if (!len)
> > +             return 0;
> > +
> > +     req->cmd = data[0] >> 4;
> > +     req->addr = (data[0] & 0xf) << 16 | data[1] << 8 | data[2];
> > +     if (len < 4) {
> > +             req->len = 0;
> > +     } else {
> > +             req->len = data[3] + 1;
> > +             memcpy(req->data, &data[4], req->len);
> > +     }
> > +
> > +     return 1;
> > +}
> > +
> > +void dprx_aux_write_response(struct dprx_dp *dp, struct aux_msg *res)
> > +{
> > +     u8 data[20];
> > +
> > +     data[0] = res->cmd << 4;
> > +     memcpy(&data[1], res->data, res->len);
> > +
> > +     dprx_dprx_write_aux(dp, data, res->len + 1);
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-dp.c b/drivers/media/platform/google/chameleonv3/dprx-dp.c
> > new file mode 100644
> > index 000000000000..ede98cb610f6
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-dp.c
> > @@ -0,0 +1,82 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2022 Google LLC.
> > + */
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/of.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/delay.h>
> > +#include "dprx.h"
> > +
> > +#define DPRX_IRQ_MASK        0x8
> > +#define DPRX_IRQ_CLR 0xc
> > +#define DPRX_IRQ_AUX         0x1
> > +
> > +static irqreturn_t dprx_dp_isr(int irq, void *data)
> > +{
> > +     struct dprx_dp *dp = data;
> > +     unsigned int reg;
> > +     struct aux_msg request;
> > +     struct aux_msg response;
> > +
> > +     reg = readl(dp->iobase_irq + DPRX_IRQ_CLR);
> > +     if (!reg)
> > +             return IRQ_NONE;
> > +     if (dprx_aux_read_request(dp, &request)) {
> > +             dprx_aux_handle_request(dp, &request, &response);
> > +             dprx_aux_write_response(dp, &response);
> > +     }
> > +     writel(reg, dp->iobase_irq + DPRX_IRQ_CLR);
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +static void dprx_sink_init(struct dprx_dp *dp)
> > +{
> > +     int i;
> > +
> > +     for (i = 0; i < 4; i++) {
> > +             memcpy(dp->sinks[i].edid, default_edid, 128 * default_edid_blocks);
> > +             dp->sinks[i].blocks = default_edid_blocks;
> > +     }
> > +}
> > +
> > +int dprx_dp_init(struct dprx_dp *dp, struct device *dev,
> > +              const struct dprx_dp_cfg *cfg)
> > +{
> > +     struct platform_device *pdev = to_platform_device(dev);
> > +     int irq;
> > +     int res;
> > +
> > +     dp->dev = &pdev->dev;
> > +
> > +     dp->iobase = devm_platform_ioremap_resource_byname(pdev, cfg->reg_core);
> > +     if (IS_ERR(dp->iobase))
> > +             return PTR_ERR(dp->iobase);
> > +
> > +     dp->iobase_irq = devm_platform_ioremap_resource_byname(pdev, cfg->reg_irq);
> > +     if (IS_ERR(dp->iobase_irq))
> > +             return PTR_ERR(dp->iobase_irq);
> > +
> > +     irq = platform_get_irq_byname(pdev, cfg->irq);
> > +     if (irq < 0)
> > +             return irq;
> > +
> > +     res = devm_request_irq(dp->dev, irq, dprx_dp_isr, 0, cfg->irq, dp);
> > +     if (res)
> > +             return res;
> > +
> > +     writel(DPRX_IRQ_AUX, dp->iobase_irq + DPRX_IRQ_MASK);
> > +
> > +     dp->has_mst = cfg->has_mst;
> > +     dp->sink_count = cfg->sink_count;
> > +
> > +     dprx_dprx_init(dp);
> > +     dprx_dpcd_init(dp);
> > +     dprx_sink_init(dp);
> > +
> > +     dprx_dprx_set_hpd(dp, 1);
> > +
> > +     return 0;
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-dpcd.c b/drivers/media/platform/google/chameleonv3/dprx-dpcd.c
> > new file mode 100644
> > index 000000000000..10110cc69dc5
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-dpcd.c
> > @@ -0,0 +1,424 @@
> > +#include <linux/string.h>
> > +#include "dprx.h"
> > +
> > +static void dpcd_clear_vc_payload_table(struct dprx_dp *dp)
> > +{
> > +     memset(dp->dpcd.vc_table, 0, 64);
> > +}
> > +
> > +static void dpcd_allocate_vc_payload(struct dprx_dp *dp, int start, int count, u8 id)
> > +{
> > +     if (count > 64 - start)
> > +             count = 64 - start;
> > +     memset(dp->dpcd.vc_table + start, id, count);
> > +}
> > +
> > +static void dpcd_deallocate_vc_payload(struct dprx_dp *dp, int start, u8 id)
> > +{
> > +     int i;
> > +     int to = start;
> > +
> > +     for (i = start; i < 64; i++) {
> > +             if (dp->dpcd.vc_table[i] == id)
> > +                     dp->dpcd.vc_table[i] = 0;
> > +             else
> > +                     dp->dpcd.vc_table[to++] = dp->dpcd.vc_table[i];
> > +     }
> > +}
> > +
> > +static void dpcd_handle_payload_allocate(struct dprx_dp *dp)
> > +{
> > +     u8 id = dp->dpcd.vc_alloc[0x0];
> > +     u8 start = dp->dpcd.vc_alloc[0x1];
> > +     u8 count = dp->dpcd.vc_alloc[0x2];
> > +
> > +     if (id == 0 && start == 0 && count == 0x3f) {
> > +             dpcd_clear_vc_payload_table(dp);
> > +             dprx_dprx_clear_vc_payload_table(dp);
> > +     } else {
> > +             if (count == 0)
> > +                     dpcd_deallocate_vc_payload(dp, start, id);
> > +             else
> > +                     dpcd_allocate_vc_payload(dp, start, count, id);
> > +             dprx_dprx_set_vc_payload_table(dp, dp->dpcd.vc_table, dp->vc_id);
> > +     }
> > +     dp->dpcd.vc_table_status |= 1 << 0;
> > +}
> > +
> > +
> > +
> > +
> > +
> > +/* 100h */
> > +static void dpcd_write_link_bw_set(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.link_conf[0x0] = val;
> > +     dprx_dprx_set_link_rate(dp, val);
> > +}
> > +
> > +/* 101h */
> > +static void dpcd_write_lane_count_set(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.link_conf[0x1] = val;
> > +     dprx_dprx_set_lane_count(dp, val & 0x1f);
> > +}
> > +
> > +/* 102h */
> > +static void dpcd_write_training_pattern_set(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.link_conf[0x2] = val;
> > +     dprx_dprx_set_training_pattern(dp, val & 0xf);
> > +     dprx_dprx_set_scrambler(dp, !((val >> 5) & 1));
> > +}
> > +
> > +/* 111h */
> > +static void dpcd_write_mstm_ctrl(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     u8 val = *src;
> > +     dp->dpcd.mstm_ctrl = val;
> > +     dprx_dprx_set_mst(dp, val & 1);
> > +}
> > +
> > +/* 1c0h */
> > +static void dpcd_write_payload_allocate_set(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.vc_alloc[0x0] = val & 0x7f;
> > +}
> > +
> > +/* 1c1h */
> > +static void dpcd_write_payload_allocate_start_time_slot(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.vc_alloc[0x1] = val & 0x3f;
> > +}
> > +
> > +/* 1c2h */
> > +static void dpcd_write_payload_allocate_time_slot_count(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.vc_alloc[0x2] = val & 0x3f;
> > +     dpcd_handle_payload_allocate(dp);
> > +}
> > +
> > +/* 201h */
> > +static void dpcd_write_device_service_irq_vector(struct dprx_dp *dp, u8 val)
> > +{
> > +     dp->dpcd.irq_vector &= ~val;
> > +
> > +     if (dprx_sbmsg_pending(dp)) {
> > +             dp->dpcd.irq_vector |= 1 << 4;
> > +             dprx_sbmsg_write(dp, dp->dpcd.down_rep, 48);
> > +             dprx_dprx_pulse_hpd(dp);
> > +     }
> > +}
> > +
> > +/* 202h */
> > +static u8 dpcd_read_lane01_status(struct dprx_dp *dp)
> > +{
> > +     int cr_lock;
> > +     int sym_lock;
> > +     u8 res = 0;
> > +
> > +     cr_lock = dprx_dprx_get_cr_lock(dp);
> > +     sym_lock = dprx_dprx_get_sym_lock(dp);
> > +     /* lane 0 */
> > +     if (cr_lock & (1 << 0))
> > +             res |= 0x1;
> > +     if (sym_lock & (1 << 0))
> > +             res |= 0x6;
> > +     /* lane 1 */
> > +     if (cr_lock & (1 << 1))
> > +             res |= 0x10;
> > +     if (sym_lock & (1 << 1))
> > +             res |= 0x60;
> > +
> > +     return res;
> > +}
> > +
> > +/* 203h */
> > +static u8 dpcd_read_lane23_status(struct dprx_dp *dp)
> > +{
> > +     int cr_lock;
> > +     int sym_lock;
> > +     u8 res = 0;
> > +
> > +     cr_lock = dprx_dprx_get_cr_lock(dp);
> > +     sym_lock = dprx_dprx_get_sym_lock(dp);
> > +     /* lane 2 */
> > +     if (cr_lock & (1 << 2))
> > +             res |= 0x1;
> > +     if (sym_lock & (1 << 2))
> > +             res |= 0x6;
> > +     /* lane 3 */
> > +     if (cr_lock & (1 << 3))
> > +             res |= 0x10;
> > +     if (sym_lock & (1 << 3))
> > +             res |= 0x60;
> > +
> > +     return res;
> > +}
> > +
> > +/* 204h */
> > +static u8 dpcd_read_lane_align_status(struct dprx_dp *dp)
> > +{
> > +     return dprx_dprx_get_interlane_align(dp);
> > +}
> > +
> > +/* 205h */
> > +static u8 dpcd_read_sink_status(struct dprx_dp *dp)
> > +{
> > +     return dprx_dprx_get_sink_status(dp);
> > +}
> > +
> > +/* 2c0h */
> > +static void dpcd_read_payload_table_update_status(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     *dest = dp->dpcd.vc_table_status;
> > +     if (dprx_dprx_get_act(dp))
> > +             *dest |= 1 << 1;
> > +}
> > +
> > +/* 2c0h */
> > +static void dpcd_write_payload_table_update_status(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     if (*src & 0x1) {
> > +             dp->dpcd.vc_table_status = 0;
> > +             dprx_dprx_clear_act(dp);
> > +     }
> > +}
> > +
> > +
> > +
> > +
> > +
> > +static void dpcd_read_caps(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.caps + offset, count);
> > +}
> > +
> > +static void dpcd_read_mstm_cap(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     *dest = dp->dpcd.mstm_cap;
> > +}
> > +
> > +static void dpcd_read_guid(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.guid + offset, count);
> > +}
> > +
> > +static void dpcd_write_guid(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     memcpy(dp->dpcd.guid + offset, src, count);
> > +}
> > +
> > +static void dpcd_read_link_conf(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.link_conf + offset, count);
> > +}
> > +
> > +static void dpcd_write_link_conf(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     if (offset <= 0 && 0 < offset + count)
> > +             dpcd_write_link_bw_set(dp, src[0 - offset]);
> > +     if (offset <= 1 && 1 < offset + count)
> > +             dpcd_write_lane_count_set(dp, src[1 - offset]);
> > +     if (offset <= 2 && 2 < offset + count)
> > +             dpcd_write_training_pattern_set(dp, src[2 - offset]);
> > +
> > +     while (dprx_dprx_get_rx_busy(dp)) {}
> > +}
> > +
> > +static void dpcd_read_mstm_ctrl(struct dprx_dp *dp, u8 *dest, u32 start, u32 count)
> > +{
> > +     *dest = dp->dpcd.mstm_ctrl;
> > +}
> > +
> > +static void dpcd_read_vc_alloc(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.vc_alloc + offset, count);
> > +}
> > +
> > +static void dpcd_write_vc_alloc(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     if (offset <= 0 && 0 < offset + count)
> > +             dpcd_write_payload_allocate_set(dp, src[0 - offset]);
> > +     if (offset <= 1 && 1 < offset + count)
> > +             dpcd_write_payload_allocate_start_time_slot(dp, src[1 - offset]);
> > +     if (offset <= 2 && 2 < offset + count)
> > +             dpcd_write_payload_allocate_time_slot_count(dp, src[2 - offset]);
> > +}
> > +
> > +static void dpcd_read_sink_stat(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     if (offset <= 0 && 0 < offset + count)
> > +             dest[0 - offset] = dp->dpcd.sink_count;
> > +     if (offset <= 1 && 1 < offset + count)
> > +             dest[1 - offset] = dp->dpcd.irq_vector;
> > +}
> > +
> > +static void dpcd_write_sink_stat(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     if (offset <= 1 && 1 < offset + count)
> > +             dpcd_write_device_service_irq_vector(dp, src[1 - offset]);
> > +}
> > +
> > +static void dpcd_read_link_stat(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     if (offset <= 0 && 0 < offset + count)
> > +             dest[0 - offset] = dpcd_read_lane01_status(dp);
> > +     if (offset <= 1 && 1 < offset + count)
> > +             dest[1 - offset] = dpcd_read_lane23_status(dp);
> > +     if (offset <= 2 && 2 < offset + count)
> > +             dest[2 - offset] = dpcd_read_lane_align_status(dp);
> > +     if (offset <= 3 && 3 < offset + count)
> > +             dest[3 - offset] = dpcd_read_sink_status(dp);
> > +     if (offset <= 4 && 4 < offset + count)
> > +             dest[4 - offset] = 0x55;
> > +     if (offset <= 5 && 5 < offset + count)
> > +             dest[5 - offset] = 0x55;
> > +}
> > +
> > +static void dpcd_read_vc_table(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.vc_table + offset + 1, count);
> > +}
> > +
> > +static void dpcd_read_sink_spec(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.sink_spec + offset, count);
> > +}
> > +
> > +static void dpcd_read_down_req(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.down_req + offset, count);
> > +}
> > +
> > +static void dpcd_write_down_req(struct dprx_dp *dp, u8 *src, u32 offset, u32 count)
> > +{
> > +     memcpy(dp->dpcd.down_req + offset, src, count);
> > +     /*
> > +      * The sideband message may require multiple AUX transactions to be
> > +      * fully written. Normally, the source writes the data in order,
> > +      * in blocks of 16. Unfortunately, the spec doesn't say what to
> > +      * do if the source behaves differently that that.
> > +      *
> > +      * Approach taken here: when we get a write, assume all the
> > +      * bytes before the starting address are valid, try to parse
> > +      * the message up to the last byte written in this transaction
> > +      * (if it's incomplete, nothing happens).
> > +      */
> > +     dprx_sbmsg_read(dp, dp->dpcd.down_req, offset + count);
> > +     if (!(dp->dpcd.irq_vector & (1 << 4)) && dprx_sbmsg_pending(dp)) {
> > +             dp->dpcd.irq_vector |= 1 << 4;
> > +             dprx_sbmsg_write(dp, dp->dpcd.down_rep, 48);
> > +             dprx_dprx_pulse_hpd(dp);
> > +     }
> > +}
> > +
> > +static void dpcd_read_down_rep(struct dprx_dp *dp, u8 *dest, u32 offset, u32 count)
> > +{
> > +     memcpy(dest, dp->dpcd.down_rep + offset, count);
> > +}
> > +
> > +struct dpcd_range {
> > +     u32 start;
> > +     u32 end;
> > +     void (*read) (struct dprx_dp *, u8 *, u32, u32);
> > +     void (*write)(struct dprx_dp *, u8 *, u32, u32);
> > +};
> > +
> > +struct dpcd_range dpcd_ranges[] = {
> > +     { 0x00000, 0x00010, dpcd_read_caps,      NULL },
> > +     { 0x00021, 0x00022, dpcd_read_mstm_cap,  NULL },
> > +     { 0x00030, 0x00040, dpcd_read_guid,      dpcd_write_guid },
> > +     { 0x00100, 0x00103, dpcd_read_link_conf, dpcd_write_link_conf },
> > +     { 0x00111, 0x00112, dpcd_read_mstm_ctrl, dpcd_write_mstm_ctrl },
> > +     { 0x001c0, 0x001c3, dpcd_read_vc_alloc,  dpcd_write_vc_alloc },
> > +     { 0x00200, 0x00202, dpcd_read_sink_stat, dpcd_write_sink_stat },
> > +     { 0x00202, 0x00208, dpcd_read_link_stat, NULL },
> > +     { 0x002c0, 0x002c1, dpcd_read_payload_table_update_status, dpcd_write_payload_table_update_status },
> > +     { 0x002c1, 0x00300, dpcd_read_vc_table,  NULL },
> > +     { 0x00400, 0x0040c, dpcd_read_sink_spec, NULL },
> > +     { 0x01000, 0x01030, dpcd_read_down_req,  dpcd_write_down_req },
> > +     { 0x01400, 0x01430, dpcd_read_down_rep,  NULL },
> > +     { 0x02002, 0x02004, dpcd_read_sink_stat, dpcd_write_sink_stat },
> > +     { 0x0200c, 0x02010, dpcd_read_link_stat, NULL },
> > +};
> > +
> > +void dprx_dpcd_access(struct dprx_dp *dp, struct aux_msg *req,
> > +                   struct aux_msg *res)
> > +{
> > +     struct dpcd_range *range;
> > +     struct dpcd_range *range_end = dpcd_ranges + ARRAY_SIZE(dpcd_ranges);
> > +     bool read = req->cmd & 1;
> > +     u32 start;
> > +     u32 end;
> > +     u8 *buf;
> > +     u32 offset;
> > +     u32 count;
> > +
> > +     res->cmd = AUX_ACK;
> > +     if (read) {
> > +             res->len = req->len;
> > +             memset(res->data, 0, res->len);
> > +     } else {
> > +             res->len = 0;
> > +     }
> > +
> > +     for (range = dpcd_ranges; range < range_end; range++) {
> > +             if (range->end <= req->addr || req->addr + req->len <= range->start)
> > +                     continue;
> > +             start = max(range->start, req->addr);
> > +             end   = min(range->end,   req->addr + req->len);
> > +             count = end - start;
> > +             offset = start - range->start;
> > +             if (read) {
> > +                     buf = res->data + (start - req->addr);
> > +                     range->read(dp, buf, offset, count);
> > +             } else if (range->write) {
> > +                     buf = req->data + (start - req->addr);
> > +                     range->write(dp, buf, offset, count);
> > +             }
> > +     }
> > +}
> > +
> > +void dprx_dpcd_init(struct dprx_dp *dp)
> > +{
> > +     struct dpcd_mem *dpcd = &dp->dpcd;
> > +
> > +     memset(dpcd, 0, sizeof(struct dpcd_mem));
> > +
> > +     dpcd->caps[0x0] = 0x14, // DPCD 1.4
> > +     dpcd->caps[0x1] = 0x1e, // Max link rate 8.1Gbps
> > +     dpcd->caps[0x2] = 0xc4, // Max lane count 4, TPS3, Enhanced frame cap
> > +     dpcd->caps[0x3] = 0x81, // Down-spread, TPS4
> > +     dpcd->caps[0x4] = 0x01, // 2 Reciever ports for SST (video & audio)
>
> Reciever -> Receiver
>
> > +     dpcd->caps[0x5] = 0x00, // no downstream ports
> > +     dpcd->caps[0x6] = 0x01, // 8b/10b support
> > +     dpcd->caps[0x7] = 0x80, // no downstream ports, OUI present
> > +     dpcd->caps[0x8] = 0x02, // has local EDID
> > +     dpcd->caps[0x9] = 0x00, // buffer size?
> > +     dpcd->caps[0xa] = 0x06,
> > +     dpcd->caps[0xb] = 0x00,
> > +     dpcd->caps[0xc] = 0x00, // no physical i2c bus
> > +     dpcd->caps[0xd] = 0x00, // reserved for eDP
> > +     dpcd->caps[0xe] = 0x00, // no extended receiver capability present
> > +     dpcd->caps[0xf] = 0x00, // no legacy adaptor caps
> > +
> > +     dpcd->mstm_cap = dp->has_mst;
> > +     dpcd->sink_count = dp->has_mst ? dp->sink_count : 1;
> > +
> > +     dpcd->sink_spec[0x0] = 0x12;
> > +     dpcd->sink_spec[0x1] = 0x34;
> > +     dpcd->sink_spec[0x2] = 0x56;
> > +     dpcd->sink_spec[0x3] = 'c';
> > +     dpcd->sink_spec[0x4] = 'h';
> > +     dpcd->sink_spec[0x5] = 'a';
> > +     dpcd->sink_spec[0x6] = 'm';
> > +     dpcd->sink_spec[0x7] = 'e';
> > +     dpcd->sink_spec[0x8] = 'l';
> > +     dpcd->sink_spec[0x9] = 0x30;
> > +     dpcd->sink_spec[0xa] = 0x00;
> > +     dpcd->sink_spec[0xb] = 0x00;
> > +
> > +     dpcd_write_link_bw_set(dp, 0x1e);
> > +     dpcd_write_lane_count_set(dp, 0x04);
> > +};
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-dprx.c b/drivers/media/platform/google/chameleonv3/dprx-dprx.c
> > new file mode 100644
> > index 000000000000..7c7b196539ed
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-dprx.c
> > @@ -0,0 +1,262 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2022 Google LLC.
> > + */
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/of.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/delay.h>
> > +
> > +#include "dprx.h"
> > +
> > +#define DPRX_RX_CONTROL   0x000
> > +#define DPRX_RX_STATUS    0x001
> > +#define DPRX0_VBID        0x02f
> > +#define DPRX_MST_CONTROL1 0x0a0
> > +#define DPRX_MST_STATUS1  0x0a1
> > +#define DPRX_MST_VCPTAB0  0x0a2
> > +#define DPRX_AUX_CONTROL  0x100
> > +#define DPRX_AUX_STATUS   0x101
> > +#define DPRX_AUX_COMMAND  0x102
> > +#define DPRX_AUX_HPD      0x119
> > +
> > +static void dp_wr(struct dprx_dp *dp, int addr, u32 val)
> > +{
> > +     writel(val, dp->iobase + (addr * 4));
> > +}
> > +
> > +static u32 dp_rd(struct dprx_dp *dp, int addr)
> > +{
> > +     return readl(dp->iobase + (addr * 4));
> > +}
> > +
> > +/* HPD */
> > +
> > +void dprx_dprx_set_hpd(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_AUX_HPD);
> > +     reg &= ~(1 << 11);
> > +     reg |= (val & 1) << 11;
> > +     dp_wr(dp, DPRX_AUX_HPD, reg);
> > +}
> > +
> > +int dprx_dprx_get_hpd(struct dprx_dp *dp)
> > +{
> > +       return (dp_rd(dp, DPRX_AUX_HPD) >> 11) & 1;
> > +}
> > +
> > +void dprx_dprx_pulse_hpd(struct dprx_dp *dp)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_AUX_HPD);
> > +     reg |= 1 << 12;
> > +     dp_wr(dp, DPRX_AUX_HPD, reg);
> > +}
> > +
> > +/* Receiver Control */
> > +
> > +void dprx_dprx_set_link_rate(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_RX_CONTROL);
> > +     reg &= ~(0xff << 16);
> > +     reg |= (val & 0xff) << 16;
> > +     reg |= 1 << 13;
> > +     dp_wr(dp, DPRX_RX_CONTROL, reg);
> > +}
> > +
> > +void dprx_dprx_set_lane_count(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_RX_CONTROL);
> > +     reg &= ~0x1f;
> > +     reg |= (val & 0x1f);
> > +     dp_wr(dp, DPRX_RX_CONTROL, reg);
> > +}
> > +
> > +void dprx_dprx_set_training_pattern(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_RX_CONTROL);
> > +     reg &= ~(0x7 << 8);
> > +     reg |= (val & 0x7) << 8;
> > +     dp_wr(dp, DPRX_RX_CONTROL, reg);
> > +}
> > +
> > +void dprx_dprx_set_scrambler(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_RX_CONTROL);
> > +     reg &= ~(1 << 7);
> > +     reg |= (~val & 1) << 7;
> > +     dp_wr(dp, DPRX_RX_CONTROL, reg);
> > +}
> > +
> > +/* Receiver Status */
> > +
> > +int dprx_dprx_get_cr_lock(struct dprx_dp *dp)
> > +{
> > +     return dp_rd(dp, DPRX_RX_STATUS) & 0xf;
> > +}
> > +
> > +int dprx_dprx_get_sym_lock(struct dprx_dp *dp)
> > +{
> > +     return (dp_rd(dp, DPRX_RX_STATUS) >> 4) & 0xf;
> > +}
> > +
> > +int dprx_dprx_get_interlane_align(struct dprx_dp *dp)
> > +{
> > +     return (dp_rd(dp, DPRX_RX_STATUS) >> 8) & 0x1;
> > +}
> > +
> > +int dprx_dprx_get_sink_status(struct dprx_dp *dp)
> > +{
> > +     return (dp_rd(dp, DPRX0_VBID) >> 7) & 0x1;
> > +}
> > +
> > +int dprx_dprx_get_rx_busy(struct dprx_dp *dp)
> > +{
> > +     return (dp_rd(dp, DPRX_RX_STATUS) >> 17) & 0x1;
> > +}
> > +
> > +/* MST */
> > +
> > +void dprx_dprx_set_mst(struct dprx_dp *dp, int val)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_MST_CONTROL1);
> > +     reg &= ~0x1;
> > +     reg |= (val & 0x1);
> > +     dp_wr(dp, DPRX_MST_CONTROL1, reg);
> > +}
> > +
> > +void dprx_dprx_clear_vc_payload_table(struct dprx_dp *dp)
> > +{
> > +     u32 reg;
> > +     int i;
> > +
> > +     for (i = 0; i < 8; i++)
> > +             dp_wr(dp, DPRX_MST_VCPTAB0 + i, 0);
> > +
> > +     reg = dp_rd(dp, DPRX_MST_CONTROL1);
> > +     reg &= ~(0xffff << 4);
> > +     reg |= 1 << 31;
> > +     dp_wr(dp, DPRX_MST_CONTROL1, reg);
> > +}
> > +
> > +void dprx_dprx_set_vc_payload_table(struct dprx_dp *dp, u8 *table, u8 *id)
> > +{
> > +     u8 map[64];
> > +     int i, j;
> > +     u32 reg;
> > +
> > +     memset(map, 0, 64);
> > +     for (i = 0; i < 4; i++) {
> > +             if (id[i] != 0 && id[i] < 64)
> > +                     map[id[i]] = i + 1;
> > +     }
> > +
> > +     for (i = 0; i < 8; i++) {
> > +             reg = 0;
> > +             for (j = 0; j < 8; j++)
> > +                     reg |= map[table[i*8+j]] << (j * 4);
> > +             dp_wr(dp, DPRX_MST_VCPTAB0 + i, reg);
> > +     }
> > +
> > +     reg = dp_rd(dp, DPRX_MST_CONTROL1);
> > +     reg &= ~(0xffff << 4);
> > +     for (i = 0; i < 4; i++)
> > +             if (id[i] != 0 && id[i] < 64)
> > +                     reg |= (i + 1) << ((i + 1) * 4);
> > +     reg |= 1 << 30;
> > +     dp_wr(dp, DPRX_MST_CONTROL1, reg);
> > +}
> > +
> > +int dprx_dprx_get_act(struct dprx_dp *dp)
> > +{
> > +     return (dp_rd(dp, DPRX_MST_STATUS1) >> 30) & 1;
> > +}
> > +
> > +void dprx_dprx_clear_act(struct dprx_dp *dp)
> > +{
> > +     u32 reg;
> > +
> > +     reg = dp_rd(dp, DPRX_MST_CONTROL1);
> > +     reg &= ~(1 << 30);
> > +     dp_wr(dp, DPRX_MST_CONTROL1, reg);
> > +}
> > +
> > +/* AUX CH */
> > +
> > +int dprx_dprx_read_aux(struct dprx_dp *dp, u8 *data)
> > +{
> > +     int length;
> > +     u32 reg;
> > +     int i;
> > +
> > +     /* check MSG_READY */
> > +     reg = dp_rd(dp, DPRX_AUX_STATUS);
> > +     if (!(reg & (1 << 31)))
> > +             return 0;
> > +
> > +     /* read LENGTH */
> > +     length = dp_rd(dp, DPRX_AUX_CONTROL) & 0x1f;
> > +     if (length > 20)
> > +             length = 20;
> > +
> > +     /* read request */
> > +     for (i = 0; i < length; i++)
> > +             data[i] = dp_rd(dp, DPRX_AUX_COMMAND + i);
> > +
> > +     return length;
> > +}
> > +
> > +void dprx_dprx_write_aux(struct dprx_dp *dp, u8 *data, int length)
> > +{
> > +     u32 reg;
> > +     int i;
> > +
> > +     /* check READY_TO_TX */
> > +     reg = dp_rd(dp, DPRX_AUX_STATUS);
> > +     if (!(reg & (1 << 30)))
> > +             return;
> > +
> > +     /* write request */
> > +     if (length > 17)
> > +             length = 17;
> > +     for (i = 0; i < length; i++)
> > +             dp_wr(dp, DPRX_AUX_COMMAND + i, data[i]);
> > +
> > +     /* write LENGTH and TX_STROBE */
> > +     reg = dp_rd(dp, DPRX_AUX_CONTROL);
> > +     reg &= ~0x1f;
> > +     reg |= length | (1 << 7);
> > +     dp_wr(dp, DPRX_AUX_CONTROL, reg);
> > +}
> > +
> > +/* Misc */
> > +
> > +void dprx_dprx_init(struct dprx_dp *dp)
> > +{
> > +     u32 reg;
> > +
> > +     /* Enable AUX_IRQ_EN */
> > +     reg = dp_rd(dp, DPRX_AUX_CONTROL);
> > +     reg |= 1 << 8;
> > +     dp_wr(dp, DPRX_AUX_CONTROL, reg);
> > +
> > +     /* Set CHANNEL_CODING_SET to 8b/10b */
> > +     reg = dp_rd(dp, DPRX_RX_CONTROL);
> > +     reg |= 1 << 5;
> > +     dp_wr(dp, DPRX_RX_CONTROL, reg);
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-edid.c b/drivers/media/platform/google/chameleonv3/dprx-edid.c
> > new file mode 100644
> > index 000000000000..19d3a6182eeb
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-edid.c
> > @@ -0,0 +1,39 @@
> > +#include <linux/kernel.h>
> > +
> > +u8 default_edid[256] = {
> > +     0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00,
> > +     0x34,0xA9,0x96,0xA2,0x01,0x01,0x01,0x01,
> > +     0x00,0x17,0x01,0x03,0x80,0x80,0x48,0x78,
> > +     0x0A,0xDA,0xFF,0xA3,0x58,0x4A,0xA2,0x29,
> > +     0x17,0x49,0x4B,0x21,0x08,0x00,0x31,0x40,
> > +     0x45,0x40,0x61,0x40,0x81,0x80,0x01,0x01,
> > +     0x01,0x01,0x01,0x01,0x01,0x01,0x08,0xE8,
> > +     0x00,0x30,0xF2,0x70,0x5A,0x80,0xB0,0x58,
> > +     0x8A,0x00,0xBA,0x88,0x21,0x00,0x00,0x1E,
> > +     0x02,0x3A,0x80,0x18,0x71,0x38,0x2D,0x40,
> > +     0x58,0x2C,0x45,0x00,0xBA,0x88,0x21,0x00,
> > +     0x00,0x1E,0x00,0x00,0x00,0xFC,0x00,0x50,
> > +     0x61,0x6E,0x61,0x73,0x6F,0x6E,0x69,0x63,
> > +     0x2D,0x54,0x56,0x0A,0x00,0x00,0x00,0xFD,
> > +     0x00,0x17,0x3D,0x0F,0x88,0x3C,0x00,0x0A,
> > +     0x20,0x20,0x20,0x20,0x20,0x20,0x01,0xA0,
> > +
> > +     0x02,0x03,0x4F,0xF0,0x57,0x1F,0x10,0x14,
> > +     0x05,0x20,0x21,0x22,0x13,0x04,0x12,0x03,
> > +     0x16,0x07,0x60,0x61,0x5D,0x5E,0x5F,0x65,
> > +     0x66,0x62,0x63,0x64,0x23,0x09,0x07,0x01,
> > +     0x7E,0x03,0x0C,0x00,0x40,0x00,0xB8,0x3C,
> > +     0x2F,0xC8,0x90,0x01,0x02,0x03,0x04,0x81,
> > +     0x41,0x01,0x9C,0x06,0x16,0x08,0x00,0x18,
> > +     0x00,0x96,0xA6,0x98,0x00,0xA8,0x00,0x67,
> > +     0xD8,0x5D,0xC4,0x01,0x78,0x80,0x03,0xE2,
> > +     0x00,0x4B,0xE4,0x0F,0x00,0x60,0x0C,0x56,
> > +     0x5E,0x00,0xA0,0xA0,0xA0,0x29,0x50,0x30,
> > +     0x20,0x35,0x00,0xBA,0x88,0x21,0x00,0x00,
> > +     0x1A,0x66,0x21,0x56,0xAA,0x51,0x00,0x1E,
> > +     0x30,0x46,0x8F,0x33,0x00,0xBA,0x88,0x21,
> > +     0x00,0x00,0x1E,0x00,0x00,0x00,0x00,0x00,
> > +     0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x5F
> > +};
>
> Running 'edid-decode -c' (git://linuxtv.org/edid-decode.git) results in a number
> of warnings and failures:
>
> ----------------
>
> edid-decode SHA: 2d44e1b01c7e 2023-03-11 18:21:51
>
> Warnings:
>
> Block 1, CTA-861 Extension Block:
>   Video Data Block: VIC 31 is the preferred timing, overriding the first detailed timings. Is this intended?
>   Video Capability Data Block: Set Selectable YCbCr Quantization to avoid interop issues.
>   Add a Colorimetry Data Block with the sRGB colorimetry bit set to avoid interop issues.
>
> Failures:
>
> Block 0, Base EDID:
>   Detailed Timing Descriptor #1: Mismatch of image size 698x392 mm vs display size 1280x720 mm.
>   Detailed Timing Descriptor #2: Mismatch of image size 698x392 mm vs display size 1280x720 mm.
> Block 1, CTA-861 Extension Block:
>   Detailed Timing Descriptor #3: Mismatch of image size 698x392 mm vs display size 1280x720 mm.
>   Detailed Timing Descriptor #4: Mismatch of image size 698x392 mm vs display size 1280x720 mm.
>
> EDID conformity: FAIL

To be honest, I just put in a random EDID so that the user can start
grabbing frames without having to set one (it was useful for testing).
It's not significant in any way. Should I remove it?

>
> > +
> > +u8 default_edid_blocks = 2;
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-i2c.c b/drivers/media/platform/google/chameleonv3/dprx-i2c.c
> > new file mode 100644
> > index 000000000000..2f0faac7352b
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-i2c.c
> > @@ -0,0 +1,41 @@
> > +#include <linux/string.h>
> > +#include "dprx.h"
> > +
> > +int dprx_i2c_read(struct sink *sink, u8 addr, u8 *buf, int len)
> > +{
> > +     int offset;
> > +
> > +     if (addr == 0x50) {
> > +             offset = sink->offset + sink->segment * 256;
> > +             if (len + offset > sink->blocks * 128)
> > +                     return -1;
> > +             memcpy(buf, sink->edid + offset, len);
> > +             sink->offset += len;
> > +     } else if (addr == 0x30) {
> > +             if (len == 1)
> > +                     buf[0] = sink->segment;
> > +             else if (len > 1)
> > +                     return -1;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +int dprx_i2c_write(struct sink *sink, u8 addr, u8 *buf, int len)
> > +{
> > +     if (addr == 0x50) {
> > +             if (len == 1)
> > +                     sink->offset = buf[0];
> > +             else if (len > 1)
> > +                     return -1;
> > +     } else if (addr == 0x30) {
> > +             if (len == 1)
> > +                     sink->segment = buf[0];
> > +             else if (len > 1)
> > +                     return -1;
> > +     } else {
> > +             return -1;
> > +     }
> > +
> > +     return 0;
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-mt.c b/drivers/media/platform/google/chameleonv3/dprx-mt.c
> > new file mode 100644
> > index 000000000000..7b39b2e41d22
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-mt.c
> > @@ -0,0 +1,184 @@
> > +#include <linux/string.h>
> > +#include "dprx.h"
> > +
> > +#define MT_GET_MESSAGE_TRANSACTION_VERSION 0x00
> > +#define MT_LINK_ADDRESS              0x01
> > +#define MT_CONNECTION_STATUS_NOTIFY 0x02
> > +#define MT_ENUM_PATH_RESOURCES       0x10
> > +#define MT_ALLOCATE_PAYLOAD  0x11
> > +#define MT_QUERY_PAYLOAD     0x12
> > +#define MT_RESOURCE_STATUS_NOTIFY 0x13
> > +#define MT_CLEAR_PAYLOAD_ID_TABLE 0x14
> > +#define MT_REMOTE_DPCD_READ  0x20
> > +#define MT_REMOTE_DPCD_WRITE 0x21
> > +#define MT_REMOTE_I2C_READ   0x22
> > +#define MT_REMOTE_I2C_WRITE  0x23
> > +#define MT_POWER_UP_PHY              0x24
> > +#define MT_POWER_DOWN_PHY    0x25
> > +#define MT_SINK_EVENT_NOTIFY 0x30
> > +#define MT_QUERY_STREAM_ENCRYPTION_STATUS 0x38
> > +
> > +#define MT_NACK 0x80
> > +#define MT_BAD_PARAM 0x4
> > +
> > +static void execute_link_address(struct dprx_dp *dp,
> > +                              struct msg_transaction *req,
> > +                              struct msg_transaction *rep)
> > +{
> > +     int ports = dp->sink_count + 1;
> > +     u8 *buf;
> > +     int i;
> > +
> > +     rep->buf[0] = MT_LINK_ADDRESS;
> > +     memcpy(rep->buf + 1, dp->dpcd.guid, 16);
> > +     rep->buf[17] = ports;
> > +     /* port 0 */
> > +     rep->buf[18] = 0x90; /* input, source device, port 0 */
> > +     rep->buf[19] = 0x40; /* no msg, connected */
> > +
> > +     buf = rep->buf + 20;
> > +     for (i = 1; i < ports; i++) {
> > +             buf[0] = 0x30 | i; /* output, sink device, port i */
> > +             buf[1] = 0x40; /* no msg, connected */
> > +             buf[2] = 0x00; /* DPCD 0 */
> > +             memset(buf + 3, 0, 16); /* GUID */
> > +             buf[19] = 0x00; /* 0 SDP streams, 0 SDP stream sinks */
> > +             buf += 20;
> > +     }
> > +     rep->len = ports * 20;
> > +}
> > +
> > +static void execute_enum_path_resources(struct dprx_dp *dp,
> > +                                     struct msg_transaction *req,
> > +                                     struct msg_transaction *rep)
> > +{
> > +     u8 port;
> > +
> > +     port = req->buf[1] >> 4;
> > +
> > +     dp->total_pbn = dp->dpcd.link_conf[0] *
> > +                     dp->dpcd.link_conf[1] * 32;
> > +
> > +     rep->buf[0] = MT_ENUM_PATH_RESOURCES;
> > +     rep->buf[1] = port << 4;
> > +     rep->buf[2] = dp->total_pbn >> 8;
> > +     rep->buf[3] = dp->total_pbn & 0xff;
> > +     rep->buf[4] = (dp->total_pbn - dp->sum_pbn) >> 8;
> > +     rep->buf[5] = (dp->total_pbn - dp->sum_pbn) & 0xff;
> > +     rep->len = 6;
> > +}
> > +
> > +static void execute_allocate_payload(struct dprx_dp *dp,
> > +                                  struct msg_transaction *req,
> > +                                  struct msg_transaction *rep)
> > +{
> > +     u8 port;
> > +     u8 id;
> > +     u16 pbn;
> > +
> > +     port = req->buf[1] >> 4;
> > +     id = req->buf[2] & 0x7f;
> > +     pbn = req->buf[3] << 8 | req->buf[4];
> > +
> > +     dp->vc_id[port-1] = id;
> > +
> > +     rep->buf[0] = MT_ALLOCATE_PAYLOAD;
> > +     rep->buf[1] = port << 4;
> > +     rep->buf[2] = id;
> > +     rep->buf[3] = pbn >> 8;
> > +     rep->buf[4] = pbn & 0xff;
> > +     rep->len = 5;
> > +}
> > +
> > +static void execute_clear_payload_id_table(struct dprx_dp *dp,
> > +                                        struct msg_transaction *req,
> > +                                        struct msg_transaction *rep)
> > +{
> > +     dprx_dprx_clear_vc_payload_table(dp);
> > +
> > +     rep->buf[0] = MT_CLEAR_PAYLOAD_ID_TABLE;
> > +     rep->len = 1;
> > +}
> > +
> > +static void execute_remote_i2c_read(struct dprx_dp *dp,
> > +                                 struct msg_transaction *req,
> > +                                 struct msg_transaction *rep)
> > +{
> > +     u8 *req_buf = req->buf;
> > +     struct sink *sink;
> > +     u8 port;
> > +     int num_write_transactions;
> > +     u8 addr;
> > +     int len;
> > +     int i;
> > +
> > +     port = req_buf[1] >> 4;
> > +
> > +     if (port < 1 || port > dp->sink_count) {
> > +             rep->buf[0] = MT_NACK | MT_REMOTE_I2C_READ;
> > +             memcpy(&rep->buf[1], dp->dpcd.guid, 16);
> > +             rep->buf[17] = MT_BAD_PARAM;
> > +             rep->buf[18] = 0;
> > +             rep->len = 18;
> > +             return;
> > +     }
> > +
> > +     sink = &dp->sinks[port-1];
> > +
> > +     num_write_transactions = req_buf[1] & 0x3;
> > +     req_buf += 2;
> > +     for (i = 0; i < num_write_transactions; i++) {
> > +             addr = req_buf[0] & 0x7f;
> > +             len = req_buf[1];
> > +             dprx_i2c_write(sink, addr, &req_buf[2], len);
> > +             req_buf += len + 3;
> > +     }
> > +     addr = req_buf[0] & 0x7f;
> > +     len = req_buf[1];
> > +
> > +     rep->buf[0] = MT_REMOTE_I2C_READ;
> > +     rep->buf[1] = port;
> > +     rep->buf[2] = len;
> > +     dprx_i2c_read(sink, addr, rep->buf + 3, len);
> > +     rep->len = len + 3;
> > +}
> > +
> > +static void execute_power_up_phy(struct dprx_dp *dp,
> > +                              struct msg_transaction *req,
> > +                              struct msg_transaction *rep)
> > +{
> > +     u8 port;
> > +
> > +     port = req->buf[1] >> 4;
> > +
> > +     rep->buf[0] = MT_POWER_UP_PHY;
> > +     rep->buf[1] = port << 4;
> > +     rep->len = 2;
> > +}
> > +
> > +void dprx_mt_execute(struct dprx_dp *dp, struct msg_transaction *req,
> > +                  struct msg_transaction *rep)
> > +{
> > +     switch (req->buf[0] & 0x7f) {
> > +     case MT_LINK_ADDRESS:
> > +             execute_link_address(dp, req, rep);
> > +             break;
> > +     case MT_ENUM_PATH_RESOURCES:
> > +             execute_enum_path_resources(dp, req, rep);
> > +             break;
> > +     case MT_ALLOCATE_PAYLOAD:
> > +             execute_allocate_payload(dp, req, rep);
> > +             break;
> > +     case MT_CLEAR_PAYLOAD_ID_TABLE:
> > +             execute_clear_payload_id_table(dp, req, rep);
> > +             break;
> > +     case MT_REMOTE_I2C_READ:
> > +             execute_remote_i2c_read(dp, req, rep);
> > +             break;
> > +     case MT_POWER_UP_PHY:
> > +             execute_power_up_phy(dp, req, rep);
> > +             break;
> > +     default:
> > +             rep->len = 0;
> > +     }
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx-sbmsg.c b/drivers/media/platform/google/chameleonv3/dprx-sbmsg.c
> > new file mode 100644
> > index 000000000000..ae5db31f225a
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx-sbmsg.c
> > @@ -0,0 +1,162 @@
> > +#include <linux/string.h>
> > +#include "dprx.h"
> > +
> > +static u8 get_hdr_crc4(const uint8_t *data, size_t num_nibbles)
> > +{
> > +     u8 bitmask = 0x80;
> > +     u8 bitshift = 7;
> > +     u8 array_index = 0;
> > +     int number_of_bits = num_nibbles * 4;
> > +     u8 remainder = 0;
> > +
> > +     while (number_of_bits != 0) {
> > +             number_of_bits--;
> > +             remainder <<= 1;
> > +             remainder |= (data[array_index] & bitmask) >> bitshift;
> > +             bitmask >>= 1;
> > +             bitshift--;
> > +             if (bitmask == 0) {
> > +                     bitmask = 0x80;
> > +                     bitshift = 7;
> > +                     array_index++;
> > +             }
> > +             if ((remainder & 0x10) == 0x10)
> > +                     remainder ^= 0x13;
> > +     }
> > +
> > +     number_of_bits = 4;
> > +     while (number_of_bits != 0) {
> > +             number_of_bits--;
> > +             remainder <<= 1;
> > +             if ((remainder & 0x10) != 0)
> > +                     remainder ^= 0x13;
> > +     }
> > +
> > +     return remainder;
> > +}
> > +
> > +static u8 get_body_crc4(const uint8_t *data, u8 number_of_bytes)
> > +{
> > +     u8 bitmask = 0x80;
> > +     u8 bitshift = 7;
> > +     u8 array_index = 0;
> > +     int number_of_bits = number_of_bytes * 8;
> > +     u16 remainder = 0;
> > +
> > +     while (number_of_bits != 0) {
> > +             number_of_bits--;
> > +             remainder <<= 1;
> > +             remainder |= (data[array_index] & bitmask) >> bitshift;
> > +             bitmask >>= 1;
> > +             bitshift--;
> > +             if (bitmask == 0) {
> > +                     bitmask = 0x80;
> > +                     bitshift = 7;
> > +                     array_index++;
> > +             }
> > +             if ((remainder & 0x100) == 0x100)
> > +                     remainder ^= 0xd5;
> > +     }
> > +
> > +     number_of_bits = 8;
> > +     while (number_of_bits != 0) {
> > +             number_of_bits--;
> > +             remainder <<= 1;
> > +             if ((remainder & 0x100) != 0)
> > +                     remainder ^= 0xd5;
> > +     }
> > +
> > +     return remainder & 0xff;
> > +}
> > +
> > +
> > +void dprx_sbmsg_read(struct dprx_dp *dp, u8 *buf, int len)
> > +{
> > +     int link_count_total;
> > +     int rad_len;
> > +     int hdr_len;
> > +     int body_len;
> > +     bool start;
> > +     bool end;
> > +     int seq_no;
> > +     struct msg_transaction *req;
> > +     struct msg_transaction *rep;
> > +
> > +     link_count_total = buf[0] >> 4;
> > +     rad_len = link_count_total / 2;
> > +     hdr_len = rad_len + 3;
> > +     body_len = buf[rad_len + 1] & 0x3f;
> > +
> > +     /* If message is incomplete, do nothing */
> > +     if (hdr_len + body_len > len)
> > +             return;
> > +
> > +     start  = (buf[rad_len + 2] >> 7) & 1;
> > +     end    = (buf[rad_len + 2] >> 6) & 1;
> > +     seq_no = (buf[rad_len + 2] >> 4) & 1;
> > +
> > +     req = &dp->mt_req[seq_no];
> > +     rep = &dp->mt_rep[seq_no];
> > +
> > +     if (start)
> > +             req->len = 0;
> > +     /* TODO: check overflow */
> > +     memcpy(req->buf + req->len, buf + hdr_len, body_len - 1);
> > +     req->len += body_len - 1;
> > +
> > +     if (end) {
> > +             rep->written = 0;
> > +             memcpy(rep->rad, buf + 1, rad_len);
> > +             rep->link_count_total = link_count_total;
> > +             dprx_mt_execute(dp, req, rep);
> > +     }
> > +}
> > +
> > +void dprx_sbmsg_write(struct dprx_dp *dp, u8 *buf, int buf_len)
> > +{
> > +     int rad_len;
> > +     int hdr_len;
> > +     int body_len;
> > +     bool start;
> > +     bool end;
> > +     u8 hdr_crc4;
> > +     u8 body_crc4;
> > +     struct msg_transaction *rep;
> > +
> > +     rep = &dp->mt_rep[dp->mt_seq_no];
> > +     if (rep->len == 0) {
> > +             dp->mt_seq_no ^= 1;
> > +             rep = &dp->mt_rep[dp->mt_seq_no];
> > +             if (rep->len == 0)
> > +                     return;
> > +     }
> > +
> > +     rad_len = rep->link_count_total / 2;
> > +     hdr_len = rad_len + 3;
> > +     body_len = min(rep->len - rep->written + 1, buf_len - hdr_len);
> > +
> > +     start = (rep->written == 0);
> > +     end   = (rep->written + body_len - 1 == rep->len);
> > +
> > +     buf[0] = rep->link_count_total << 4 | ((rep->link_count_total - 1) & 0xf);
> > +     memcpy(buf + 1, rep->rad, rad_len);
> > +     buf[rad_len + 1] = body_len;
> > +     buf[rad_len + 2] = start << 7 | end << 6 | dp->mt_seq_no << 4;
> > +     hdr_crc4 = get_hdr_crc4(buf, hdr_len * 2 - 1);
> > +     buf[rad_len + 2] |= hdr_crc4;
> > +     memcpy(buf + hdr_len, rep->buf + rep->written, body_len - 1);
> > +     body_crc4 = get_body_crc4(buf + hdr_len, body_len - 1);
> > +     buf[hdr_len + body_len - 1] = body_crc4;
> > +     rep->written += body_len - 1;
> > +
> > +     if (end) {
> > +             rep->len = 0;
> > +             rep->written = 0;
> > +             dp->mt_seq_no ^= 1;
> > +     }
> > +}
> > +
> > +bool dprx_sbmsg_pending(struct dprx_dp *dp)
> > +{
> > +     return dp->mt_rep[0].len > 0 || dp->mt_rep[1].len > 0;
> > +}
> > diff --git a/drivers/media/platform/google/chameleonv3/dprx.h b/drivers/media/platform/google/chameleonv3/dprx.h
> > new file mode 100644
> > index 000000000000..8c48b775c9bd
> > --- /dev/null
> > +++ b/drivers/media/platform/google/chameleonv3/dprx.h
> > @@ -0,0 +1,128 @@
> > +#include <linux/kernel.h>
> > +
> > +struct dprx_dp_cfg {
> > +     const char *reg_core;
> > +     const char *reg_irq;
> > +     const char *irq;
> > +     int has_mst;
> > +     int sink_count;
> > +};
> > +
> > +struct msg_transaction {
> > +       u8 buf[256];
> > +       int len;
> > +       int written;
> > +       u8 rad[16];
> > +       int link_count_total;
> > +};
> > +
> > +struct dpcd_mem {
> > +       u8 caps[0x10];        /* 00000 - 0000f */
> > +       u8 mstm_cap;          /* 00021         */
> > +       u8 guid[0x10];        /* 00030 - 0003f */
> > +       u8 link_conf[0x3];    /* 00100 - 00102 */
> > +       u8 mstm_ctrl;         /* 00111         */
> > +       u8 vc_alloc[0x3];     /* 001c0 - 001c2 */
> > +       u8 sink_count;        /* 00200         */
> > +       u8 irq_vector;        /* 00201         */
> > +       u8 lane_align_status; /* 00204         */
> > +       u8 vc_table_status;   /* 0x2c0         */
> > +       u8 vc_table[0x40];    /* 002c1 - 002ff */
> > +       u8 sink_spec[0xc];    /* 00400 - 0040b */
> > +       u8 down_req[0x30];    /* 01000 - 01030 */
> > +       u8 down_rep[0x30];    /* 01400 - 01430 */
> > +};
> > +
> > +#define DPRX_MAX_EDID_BLOCKS 4
> > +
> > +struct sink {
> > +       u8 edid[128 * DPRX_MAX_EDID_BLOCKS];
> > +       int blocks;
> > +       int offset;
> > +       int segment;
> > +};
> > +
> > +struct dprx_dp {
> > +       struct device *dev;
> > +       void __iomem *iobase;
> > +       void __iomem *iobase_irq;
> > +
> > +       struct sink sinks[4];
> > +       u8 vc_id[4];
> > +       int sink_count;
> > +       int has_mst;
> > +       int total_pbn;
> > +       int sum_pbn;
> > +
> > +       /* dpcd */
> > +       struct dpcd_mem dpcd;
> > +
> > +       /* msg transaction */
> > +       struct msg_transaction mt_req[2];
> > +       struct msg_transaction mt_rep[2];
> > +       bool mt_seq_no;
> > +};
> > +
> > +int dprx_dp_init(struct dprx_dp *dp, struct device *dev,
> > +              const struct dprx_dp_cfg *cfg);
> > +
> > +#define AUX_ACK 0x0
> > +#define AUX_I2C_NACK 0x4
> > +
> > +struct aux_msg {
> > +     u8 cmd;
> > +     u32 addr;
> > +     u8 len;
> > +     u8 data[16];
> > +};
> > +
> > +/* dprx-aux.c */
> > +void dprx_aux_handle_request(struct dprx_dp *dp, struct aux_msg *req,
> > +                          struct aux_msg *res);
> > +int dprx_aux_read_request(struct dprx_dp *dp, struct aux_msg *req);
> > +void dprx_aux_write_response(struct dprx_dp *dp, struct aux_msg *res);
> > +
> > +/* dprx-dpcd.c */
> > +void dprx_dpcd_init(struct dprx_dp *dp);
> > +void dprx_dpcd_access(struct dprx_dp *dp, struct aux_msg *req,
> > +                   struct aux_msg *res);
> > +
> > +
> > +/* dprx-dprx.c */
> > +void dprx_dprx_set_hpd(struct dprx_dp *dp, int val);
> > +int dprx_dprx_get_hpd(struct dprx_dp *dp);
> > +void dprx_dprx_pulse_hpd(struct dprx_dp *dp);
> > +void dprx_dprx_set_link_rate(struct dprx_dp *dp, int val);
> > +void dprx_dprx_set_lane_count(struct dprx_dp *dp, int val);
> > +void dprx_dprx_set_training_pattern(struct dprx_dp *dp, int val);
> > +void dprx_dprx_set_scrambler(struct dprx_dp *dp, int val);
> > +int dprx_dprx_get_cr_lock(struct dprx_dp *dp);
> > +int dprx_dprx_get_sym_lock(struct dprx_dp *dp);
> > +int dprx_dprx_get_interlane_align(struct dprx_dp *dp);
> > +int dprx_dprx_get_sink_status(struct dprx_dp *dp);
> > +int dprx_dprx_get_rx_busy(struct dprx_dp *dp);
> > +void dprx_dprx_set_mst(struct dprx_dp *dp, int val);
> > +void dprx_dprx_clear_vc_payload_table(struct dprx_dp *dp);
> > +void dprx_dprx_set_vc_payload_table(struct dprx_dp *dp, u8 *table, u8 *id);
> > +int dprx_dprx_get_act(struct dprx_dp *dp);
> > +void dprx_dprx_clear_act(struct dprx_dp *dp);
> > +int dprx_dprx_read_aux(struct dprx_dp *dp, u8 *data);
> > +void dprx_dprx_write_aux(struct dprx_dp *dp, u8 *data, int length);
> > +void dprx_dprx_init(struct dprx_dp *dp);
> > +
> > +/* dprx-edid.c */
> > +extern u8 default_edid[256];
> > +extern u8 default_edid_blocks;
> > +
> > +/* dprx-i2c.c */
> > +int dprx_i2c_read(struct sink *sink, u8 addr, u8 *buf, int len);
> > +int dprx_i2c_write(struct sink *sink, u8 addr, u8 *buf, int len);
> > +
> > +/* dprx-mt.c */
> > +void dprx_mt_execute(struct dprx_dp *dp, struct msg_transaction *req,
> > +                  struct msg_transaction *rep);
> > +
> > +/* dprx-sbmsg.c */
> > +void dprx_sbmsg_read(struct dprx_dp *dp, u8 *buf, int len);
> > +void dprx_sbmsg_write(struct dprx_dp *dp, u8 *buf, int buf_len);
> > +bool dprx_sbmsg_pending(struct dprx_dp *dp);
>
> Regards,
>
>         Hans

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