Date:   Sun, 6 Nov 2016 17:56:20 -0800
From:   Matt Ranostay <matt@...ostay.consulting>
To:     Matt Ranostay <mranostay@...il.com>
Cc:     Linux Media Mailing List <linux-media@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Attila Kinali <attila@...ali.ch>, Marek Vasut <marex@...x.de>,
        Luca Barbato <lu_zero@...too.org>
Subject: Re: [PATCH] media: i2c-polling: add i2c-polling driver

On Sun, Nov 6, 2016 at 5:21 PM, Matt Ranostay <mranostay@...il.com> wrote:
> There are several thermal sensors that only have a low-speed bus
> interface but output valid video data. This patchset enables support
> for the AMG88xx "Grid-Eye" sensor family.
>
> Cc: Attila Kinali <attila@...ali.ch>
> Cc: Marek Vasut <marex@...x.de>
> Cc: Luca Barbato <lu_zero@...too.org>
> Signed-off-by: Matt Ranostay <matt@...ostay.consulting>
> ---
>  drivers/media/i2c/Kconfig       |   8 +
>  drivers/media/i2c/Makefile      |   1 +
>  drivers/media/i2c/i2c-polling.c | 466 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 475 insertions(+)
>  create mode 100644 drivers/media/i2c/i2c-polling.c
>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 2669b4bad910..6346eeecfaae 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -768,6 +768,14 @@ config VIDEO_M52790
>
>          To compile this driver as a module, choose M here: the
>          module will be called m52790.
> +
> +config VIDEO_I2C_POLLING
> +       tristate "I2C polling video support"
> +       depends on VIDEO_V4L2 && I2C
> +       select VIDEOBUF2_VMALLOC
> +       ---help---
> +         Enable the I2C polling video support which supports the following:
> +          * Panasonic AMG88xx Grid-Eye Sensors
>  endmenu
>
>  menu "Sensors used on soc_camera driver"
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 92773b2e6225..8182ec9f66b9 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -79,6 +79,7 @@ obj-$(CONFIG_VIDEO_LM3646)    += lm3646.o
>  obj-$(CONFIG_VIDEO_SMIAPP_PLL) += smiapp-pll.o
>  obj-$(CONFIG_VIDEO_AK881X)             += ak881x.o
>  obj-$(CONFIG_VIDEO_IR_I2C)  += ir-kbd-i2c.o
> +obj-$(CONFIG_VIDEO_I2C_POLLING)        += i2c-polling.o
>  obj-$(CONFIG_VIDEO_ML86V7667)  += ml86v7667.o
>  obj-$(CONFIG_VIDEO_OV2659)     += ov2659.o
>  obj-$(CONFIG_VIDEO_TC358743)   += tc358743.o
> diff --git a/drivers/media/i2c/i2c-polling.c b/drivers/media/i2c/i2c-polling.c
> new file mode 100644
> index 000000000000..753e355b5fa9
> --- /dev/null
> +++ b/drivers/media/i2c/i2c-polling.c
> @@ -0,0 +1,466 @@
> +/*
> + * i2c_polling.c - Support for polling I2C video devices
> + *
> + * Copyright (C) 2016 Matt Ranostay <mranostay@...ostay.consulting>
> + *
> + * Based on the orginal work drivers/media/parport/bw-qcam.c
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * Supported:
> + * - Panasonic AMG88xx Grid-Eye Sensors
> + */
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/delay.h>
> +#include <linux/videodev2.h>
> +#include <linux/mutex.h>
> +#include <linux/i2c.h>
> +#include <media/v4l2-common.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fh.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-event.h>
> +#include <media/videobuf2-vmalloc.h>
> +
> +#define I2C_POLLING_DRIVER     "i2c-polling"
> +
> +struct i2c_polling_chip;
> +
> +struct i2c_polling_data {
> +       struct i2c_client *client;
> +       const struct i2c_polling_chip *chip;
> +       struct mutex lock;
> +       struct mutex queue_lock;
> +       unsigned int last_update;
> +
> +       struct v4l2_device v4l2_dev;
> +       struct video_device vdev;
> +       struct vb2_queue vb_vidq;
> +};
> +
> +static struct v4l2_fmtdesc amg88xx_format = {
> +       .description = "12-bit Greyscale",
> +       .pixelformat = V4L2_PIX_FMT_Y12,
> +};
> +
> +static struct v4l2_frmsize_discrete amg88xx_size = {
> +       .width = 8,
> +       .height = 8,
> +};
> +
> +struct i2c_polling_chip {
> +       /* video dimensions */
> +       struct v4l2_fmtdesc *format;
> +       struct v4l2_frmsize_discrete *size;
> +
> +       /* max frames per second */
> +       unsigned int max_fps;
> +
> +       /* pixel buffer size */
> +       unsigned int buffer_size;
> +
> +       /* xfer function */
> +       int (*xfer)(struct i2c_polling_data *data, char *buf);
> +};
> +
> +enum {
> +       AMG88XX = 0,
> +       I2C_POLLING_CHIP_CNT,
> +};
> +
> +static int amg88xx_xfer(struct i2c_polling_data *data, char *buf)
> +{
> +       struct i2c_client *client = data->client;
> +       struct i2c_msg msg[2];
> +       u8 reg = 0x80;
> +       int ret;
> +
> +       msg[0].addr = client->addr;
> +       msg[0].flags = 0;
> +       msg[0].len = 1;
> +       msg[0].buf  = (char *) &reg;
> +
> +       msg[1].addr = client->addr;
> +       msg[1].flags = I2C_M_RD;
> +       msg[1].len = data->chip->buffer_size;
> +       msg[1].buf = (char *) buf;
> +
> +       ret = i2c_transfer(client->adapter, msg, 2);
> +
> +       return (ret == 2) ? 0 : -EIO;
> +}
> +
> +static const struct i2c_polling_chip i2c_polling_chips[I2C_POLLING_CHIP_CNT] = {
> +       [AMG88XX] = {
> +               .size           = &amg88xx_size,
> +               .format         = &amg88xx_format,
> +               .max_fps        = 10,
> +               .buffer_size    = 128,
> +               .xfer           = &amg88xx_xfer,
> +       },
> +};
> +
> +static const struct v4l2_file_operations i2c_polling_fops = {
> +       .owner          = THIS_MODULE,
> +       .open           = v4l2_fh_open,
> +       .release        = vb2_fop_release,
> +       .poll           = vb2_fop_poll,
> +       .unlocked_ioctl = video_ioctl2,
> +       .read           = vb2_fop_read,
> +       .mmap           = vb2_fop_mmap,
> +};
> +
> +static int queue_setup(struct vb2_queue *vq,
> +                      unsigned int *nbuffers, unsigned int *nplanes,
> +                      unsigned int sizes[], struct device *alloc_devs[])
> +{
> +       struct i2c_polling_data *data = vb2_get_drv_priv(vq);
> +
> +       if (!(*nbuffers))
> +               *nbuffers = 3;
> +
> +       *nplanes = 1;
> +       sizes[0] = data->chip->buffer_size;
> +
> +       return 0;
> +}
> +
> +static void buffer_queue(struct vb2_buffer *vb)
> +{
> +       struct i2c_polling_data *data = vb2_get_drv_priv(vb->vb2_queue);
> +       int delta;
> +
> +       mutex_lock(&data->lock);
> +
> +       delta = jiffies - data->last_update;
> +
> +       if (delta < msecs_to_jiffies(100)) {

After submitting I noticed the 100 milliseconds should be calculated
from the max_fps.

> +               int tmp = (100 - jiffies_to_msecs(delta)) * 1000;
> +
> +               usleep_range(tmp, tmp + 1000);
> +       }
> +       data->last_update = jiffies;
> +
> +       mutex_unlock(&data->lock);
> +
> +       vb2_buffer_done(vb, VB2_BUF_STATE_DONE);
> +}
> +
> +static void buffer_finish(struct vb2_buffer *vb)
> +{
> +       struct i2c_polling_data *data = vb2_get_drv_priv(vb->vb2_queue);
> +       void *vbuf = vb2_plane_vaddr(vb, 0);
> +       int size = vb2_plane_size(vb, 0);
> +       int ret;
> +
> +       mutex_lock(&data->lock);
> +
> +       ret = data->chip->xfer(data, vbuf);
> +       if (ret < 0)
> +               vb->state = VB2_BUF_STATE_ERROR;
> +
> +       mutex_unlock(&data->lock);
> +
> +       vb->timestamp = ktime_get_ns();
> +       vb2_set_plane_payload(vb, 0, ret ? 0 : size);
> +}
> +
> +static struct vb2_ops i2c_polling_video_qops = {
> +       .queue_setup    = queue_setup,
> +       .buf_queue      = buffer_queue,
> +       .buf_finish     = buffer_finish,
> +       .wait_prepare   = vb2_ops_wait_prepare,
> +       .wait_finish    = vb2_ops_wait_finish,
> +};
> +
> +static int i2c_polling_querycap(struct file *file, void  *priv,
> +                               struct v4l2_capability *vcap)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +
> +       strlcpy(vcap->driver, data->v4l2_dev.name, sizeof(vcap->driver));
> +       strlcpy(vcap->card, "I2C Polling Video", sizeof(vcap->card));
> +
> +       strlcpy(vcap->bus_info, "I2C:i2c-polling", sizeof(vcap->bus_info));
> +       vcap->device_caps = V4L2_CAP_VIDEO_CAPTURE |
> +                           V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
> +       vcap->capabilities = vcap->device_caps | V4L2_CAP_DEVICE_CAPS;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_g_input(struct file *file, void *fh, unsigned int *inp)
> +{
> +       *inp = 0;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_s_input(struct file *file, void *fh, unsigned int inp)
> +{
> +       return (inp > 0) ? -EINVAL : 0;
> +}
> +
> +static int i2c_polling_enum_input(struct file *file, void *fh,
> +                                 struct v4l2_input *vin)
> +{
> +       if (vin->index > 0)
> +               return -EINVAL;
> +
> +       strlcpy(vin->name, "Camera", sizeof(vin->name));
> +
> +       vin->type = V4L2_INPUT_TYPE_CAMERA;
> +       vin->audioset = 0;
> +       vin->tuner = 0;
> +       vin->std = 0;
> +       vin->status = 0;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_enum_fmt_vid_cap(struct file *file, void *fh,
> +                                       struct v4l2_fmtdesc *fmt)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +       enum v4l2_buf_type type = fmt->type;
> +
> +       if (fmt->index > 0)
> +               return -EINVAL;
> +
> +       *fmt = *data->chip->format;
> +       fmt->type = type;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_enum_framesizes(struct file *file, void *fh,
> +                                      struct v4l2_frmsizeenum *fsize)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +       struct v4l2_frmsize_discrete *size = data->chip->size;
> +
> +       /* currently only one frame size is allowed */
> +       if (fsize->index > 0)
> +               return -EINVAL;
> +
> +       if (fsize->pixel_format != data->chip->format->pixelformat)
> +               return -EINVAL;
> +
> +       fsize->type = V4L2_FRMSIZE_TYPE_DISCRETE;
> +       fsize->discrete.width = size->width;
> +       fsize->discrete.height = size->height;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_enum_frameintervals(struct file *file, void *priv,
> +                                          struct v4l2_frmivalenum *fe)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +       struct v4l2_frmsize_discrete *size = data->chip->size;
> +
> +       if (fe->index > 0)
> +               return -EINVAL;
> +
> +       if ((fe->width != size->width) || (fe->height != size->height))
> +               return -EINVAL;
> +
> +       fe->type = V4L2_FRMIVAL_TYPE_DISCRETE;
> +       fe->discrete.numerator = 1;
> +       fe->discrete.denominator = data->chip->max_fps;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_try_fmt_vid_cap(struct file *file, void *fh,
> +                                      struct v4l2_format *fmt)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +       struct v4l2_pix_format *pix = &fmt->fmt.pix;
> +       struct v4l2_frmsize_discrete *size = data->chip->size;
> +
> +       pix->width = size->width;
> +       pix->height = size->height;
> +       pix->pixelformat = data->chip->format->pixelformat;
> +       pix->field = V4L2_FIELD_NONE;
> +       pix->bytesperline = pix->width * 2;
> +       pix->sizeimage = pix->width * pix->height * 2;
> +       pix->colorspace = V4L2_COLORSPACE_SRGB;
> +       pix->priv = 0;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_fmt_vid_cap(struct file *file, void *fh,
> +                                    struct v4l2_format *fmt)
> +{
> +       struct i2c_polling_data *data = video_drvdata(file);
> +       int ret = i2c_polling_try_fmt_vid_cap(file, fh, fmt);
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       if (vb2_is_busy(&data->vb_vidq))
> +               return -EBUSY;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_g_parm(struct file *filp, void *priv,
> +                             struct v4l2_streamparm *parm)
> +{
> +       struct i2c_polling_data *data = video_drvdata(filp);
> +
> +       if (parm->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
> +               return -EINVAL;
> +
> +       parm->parm.capture.readbuffers = 3;
> +       parm->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
> +       parm->parm.capture.timeperframe.numerator = 1;
> +       parm->parm.capture.timeperframe.denominator = data->chip->max_fps;
> +
> +       return 0;
> +}
> +
> +static int i2c_polling_s_parm(struct file *filp, void *priv,
> +                             struct v4l2_streamparm *parm)
> +{
> +       if (parm->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
> +               return -EINVAL;
> +
> +       return i2c_polling_g_parm(filp, priv, parm);
> +}
> +
> +static const struct v4l2_ioctl_ops i2c_polling_ioctl_ops = {
> +       .vidioc_querycap                = i2c_polling_querycap,
> +       .vidioc_g_input                 = i2c_polling_g_input,
> +       .vidioc_s_input                 = i2c_polling_s_input,
> +       .vidioc_enum_input              = i2c_polling_enum_input,
> +       .vidioc_enum_fmt_vid_cap        = i2c_polling_enum_fmt_vid_cap,
> +       .vidioc_enum_framesizes         = i2c_polling_enum_framesizes,
> +       .vidioc_enum_frameintervals     = i2c_polling_enum_frameintervals,
> +       .vidioc_g_fmt_vid_cap           = i2c_polling_fmt_vid_cap,
> +       .vidioc_s_fmt_vid_cap           = i2c_polling_fmt_vid_cap,
> +       .vidioc_g_parm                  = i2c_polling_g_parm,
> +       .vidioc_s_parm                  = i2c_polling_s_parm,
> +       .vidioc_try_fmt_vid_cap         = i2c_polling_try_fmt_vid_cap,
> +       .vidioc_reqbufs                 = vb2_ioctl_reqbufs,
> +       .vidioc_create_bufs             = vb2_ioctl_create_bufs,
> +       .vidioc_prepare_buf             = vb2_ioctl_prepare_buf,
> +       .vidioc_querybuf                = vb2_ioctl_querybuf,
> +       .vidioc_qbuf                    = vb2_ioctl_qbuf,
> +       .vidioc_dqbuf                   = vb2_ioctl_dqbuf,
> +       .vidioc_streamon                = vb2_ioctl_streamon,
> +       .vidioc_streamoff               = vb2_ioctl_streamoff,
> +       .vidioc_log_status              = v4l2_ctrl_log_status,
> +       .vidioc_subscribe_event         = v4l2_ctrl_subscribe_event,
> +       .vidioc_unsubscribe_event       = v4l2_event_unsubscribe,
> +};
> +
> +static int i2c_polling_probe(struct i2c_client *client,
> +                            const struct i2c_device_id *id)
> +{
> +       struct i2c_polling_data *data;
> +       struct v4l2_device *v4l2_dev;
> +       struct vb2_queue *queue;
> +       int ret;
> +
> +       data = kzalloc(sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       data->chip = &i2c_polling_chips[id->driver_data];
> +       data->client = client;
> +       data->last_update = jiffies;
> +       v4l2_dev = &data->v4l2_dev;
> +       strlcpy(v4l2_dev->name, I2C_POLLING_DRIVER, sizeof(v4l2_dev->name));
> +
> +       ret = v4l2_device_register(&client->dev, v4l2_dev);
> +       if (ret < 0)
> +               goto error_free_device;
> +
> +       mutex_init(&data->lock);
> +       mutex_init(&data->queue_lock);
> +
> +       queue = &data->vb_vidq;
> +       queue->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +       queue->io_modes = VB2_MMAP | VB2_USERPTR | VB2_READ;
> +       queue->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +       queue->drv_priv = data;
> +       queue->ops = &i2c_polling_video_qops;
> +       queue->mem_ops = &vb2_vmalloc_memops;
> +
> +       ret = vb2_queue_init(queue);
> +       if (ret < 0)
> +               goto error_free_device;
> +
> +       data->vdev.queue = queue;
> +       data->vdev.queue->lock = &data->queue_lock;
> +
> +       strlcpy(data->vdev.name, "I2C Polling Video", sizeof(data->vdev.name));
> +
> +       data->vdev.v4l2_dev = v4l2_dev;
> +       data->vdev.fops = &i2c_polling_fops;
> +       data->vdev.lock = &data->lock;
> +       data->vdev.ioctl_ops = &i2c_polling_ioctl_ops;
> +       data->vdev.release = video_device_release_empty;
> +
> +       video_set_drvdata(&data->vdev, data);
> +       i2c_set_clientdata(client, data);
> +
> +       ret = video_register_device(&data->vdev, VFL_TYPE_GRABBER, -1);
> +       if (ret < 0)
> +               goto error_unregister_device;
> +
> +       return 0;
> +
> +error_unregister_device:
> +       v4l2_device_unregister(v4l2_dev);
> +
> +error_free_device:
> +       kfree(data);
> +
> +       return ret;
> +}
> +
> +static int i2c_polling_remove(struct i2c_client *client)
> +{
> +       struct i2c_polling_data *data = i2c_get_clientdata(client);
> +
> +       v4l2_device_unregister(&data->v4l2_dev);
> +       kfree(data);
> +
> +       return 0;
> +}
> +
> +static const struct i2c_device_id i2c_polling_id_table[] = {
> +       { "amg88xx", AMG88XX },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(i2c, i2c_polling_id_table);
> +
> +static struct i2c_driver i2c_polling_driver = {
> +       .driver = {
> +               .name   = I2C_POLLING_DRIVER,
> +       },
> +       .probe          = i2c_polling_probe,
> +       .remove         = i2c_polling_remove,
> +       .id_table       = i2c_polling_id_table,
> +};
> +
> +module_i2c_driver(i2c_polling_driver);
> +
> +MODULE_AUTHOR("Matt Ranostay <mranostay@...ostay.consulting>");
> +MODULE_DESCRIPTION("I2C polling video support");
> +MODULE_LICENSE("GPL");
> --
> 2.7.4
>

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