Date:   Tue, 14 Feb 2023 23:32:24 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Wentong Wu <wentong.wu@...el.com>
Cc:     mchehab@...nel.org, linux-media@...r.kernel.org,
        srinivas.pandruvada@...el.com,
        pierre-louis.bossart@...ux.intel.com, zhifeng.wang@...el.com,
        xiang.ye@...el.com, tian.shu.qiu@...el.com, bingbu.cao@...el.com,
        linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2 1/3] media: pci: intel: ivsc: Add CSI submodule

Hi Wentong,

Cc'ing Hans as well.

On Mon, Feb 13, 2023 at 10:23:45AM +0800, Wentong Wu wrote:
> CSI is a submodule of IVSC which can route camera sensor data
> to the outbound MIPI CSI-2 interface.
> 
> The interface communicating with firmware is via MEI. There is
> a separate MEI UUID, which this driver uses to enumerate.
> 
> To route camera sensor data to host, the caller specifies link
> frequency and number of data lanes. This information is sent to
> firmware by sending MEI command.
> 
> Two APIs are exported: csi_set_link_owner is used to switch
> ownership of CSI-2 link, and csi_set_link_cfg is to configure
> CSI-2 link when routing camera sensor data to host.
> 
> CSI also provides a privacy mode. When privacy mode is turned
> on, camera sensor can't be used. This means that both IVSC and
> host Image Processing Unit(IPU) can't get image data. And when
> this mode is turned on, host Image Processing Unit(IPU) driver
> is informed via the registered callback, so that user can be
> notified.
> 
> Signed-off-by: Wentong Wu <wentong.wu@...el.com>
> ---
>  drivers/media/pci/Kconfig              |   1 +
>  drivers/media/pci/intel/Makefile       |   2 +
>  drivers/media/pci/intel/ivsc/Kconfig   |  12 +
>  drivers/media/pci/intel/ivsc/Makefile  |   5 +
>  drivers/media/pci/intel/ivsc/mei_csi.c | 342 +++++++++++++++++++++++++
>  drivers/media/pci/intel/ivsc/mei_csi.h |  60 +++++
>  include/linux/ivsc.h                   |  19 ++

Please add a MAINTAINERS entry for this (ivsc dir).

>  7 files changed, 441 insertions(+)
>  create mode 100644 drivers/media/pci/intel/ivsc/Kconfig
>  create mode 100644 drivers/media/pci/intel/ivsc/Makefile
>  create mode 100644 drivers/media/pci/intel/ivsc/mei_csi.c
>  create mode 100644 drivers/media/pci/intel/ivsc/mei_csi.h
>  create mode 100644 include/linux/ivsc.h
> 
> diff --git a/drivers/media/pci/Kconfig b/drivers/media/pci/Kconfig
> index 1224d908713a..16661ab0b816 100644
> --- a/drivers/media/pci/Kconfig
> +++ b/drivers/media/pci/Kconfig
> @@ -74,6 +74,7 @@ config VIDEO_PCI_SKELETON
>  	  when developing new drivers.
>  
>  source "drivers/media/pci/intel/ipu3/Kconfig"
> +source "drivers/media/pci/intel/ivsc/Kconfig"
>  
>  endif #MEDIA_PCI_SUPPORT
>  endif #PCI
> diff --git a/drivers/media/pci/intel/Makefile b/drivers/media/pci/intel/Makefile
> index 0b4236c4db49..d27ca636c860 100644
> --- a/drivers/media/pci/intel/Makefile
> +++ b/drivers/media/pci/intel/Makefile
> @@ -4,3 +4,5 @@
>  #
>  
>  obj-y	+= ipu3/
> +
> +obj-$(CONFIG_INTEL_VSC) += ivsc/
> diff --git a/drivers/media/pci/intel/ivsc/Kconfig b/drivers/media/pci/intel/ivsc/Kconfig
> new file mode 100644
> index 000000000000..9535ac10f4f7
> --- /dev/null
> +++ b/drivers/media/pci/intel/ivsc/Kconfig
> @@ -0,0 +1,12 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +# Copyright (C) 2023, Intel Corporation. All rights reserved.
> +
> +config INTEL_VSC
> +	tristate "Intel Visual Sensing Controller"
> +	depends on INTEL_MEI
> +	help
> +	  This adds support for Intel Visual Sensing Controller (IVSC).
> +
> +	  Enables the IVSC firmware services required for controlling
> +	  camera sensor ownership and CSI-2 link through Image Processing
> +	  Unit(IPU) driver of Intel.
> diff --git a/drivers/media/pci/intel/ivsc/Makefile b/drivers/media/pci/intel/ivsc/Makefile
> new file mode 100644
> index 000000000000..1825aad45cff
> --- /dev/null
> +++ b/drivers/media/pci/intel/ivsc/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Copyright (C) 2023, Intel Corporation. All rights reserved.
> +
> +obj-$(CONFIG_INTEL_VSC) += mei_csi.o
> diff --git a/drivers/media/pci/intel/ivsc/mei_csi.c b/drivers/media/pci/intel/ivsc/mei_csi.c
> new file mode 100644
> index 000000000000..309e52387502
> --- /dev/null
> +++ b/drivers/media/pci/intel/ivsc/mei_csi.c
> @@ -0,0 +1,342 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2023 Intel Corporation. All rights reserved.

Do you still need the "all rights reserved" part?

> + * Intel Visual Sensing Controller CSI Linux driver
> + */
> +
> +/*

You can merge the two comments.

> + * To set ownership of CSI-2 link and to configure CSI-2 link, there
> + * are specific commands, which are sent via MEI protocol. The send
> + * command function uses "completion" as a synchronization mechanism.
> + * The response for command is received via a mei callback which wakes
> + * up the caller. There can be only one outstanding command at a time.
> + */
> +
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/math64.h>
> +#include <linux/mei_cl_bus.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/units.h>
> +#include <linux/uuid.h>
> +#include <linux/workqueue.h>
> +
> +#include "mei_csi.h"
> +
> +#define MEI_CSI_DRIVER_NAME "ivsc_csi"
> +
> +/* the 5s used here is based on experiment */
> +#define CSI_CMD_TIMEOUT (5 * HZ)
> +/* to setup CSI-2 link an extra delay needed and determined experimentally */
> +#define CSI_FW_READY_DELAY_MS 100
> +/* link frequency unit is 100kHz */
> +#define CSI_LINK_FREQ(x) ((u32)(div_u64(x, 100 * HZ_PER_KHZ)))
> +
> +/*
> + * identify the command id supported by firmware
> + * IPC, as well as the privacy notification id
> + * used when processing privacy event.
> + */
> +enum csi_cmd_id {
> +	/* used to set csi ownership */
> +	CSI_SET_OWNER = 0,
> +
> +	/* used to configure CSI-2 link */
> +	CSI_SET_CONF = 2,
> +
> +	/* privacy notification id used when privacy state changes */
> +	CSI_PRIVACY_NOTIF = 6,
> +};
> +
> +/* configuration of the CSI-2 link between host and IVSC */
> +struct csi_link_cfg {
> +	/* number of data lanes used on the CSI-2 link */
> +	u32 nr_of_lanes;
> +
> +	/* frequency of the CSI-2 link */
> +	u32 link_freq;
> +
> +	/* for future use */
> +	u32 rsvd[2];
> +} __packed;
> +
> +/* CSI command structure */
> +struct csi_cmd {
> +	u32 cmd_id;
> +	union _cmd_param {
> +		u32 param;
> +		struct csi_link_cfg conf;
> +	} param;
> +} __packed;
> +
> +/* CSI notification structure */
> +struct csi_notif {
> +	u32 cmd_id;
> +	int status;
> +	union _resp_cont {
> +		u32 cont;
> +		struct csi_link_cfg conf;
> +	} cont;
> +} __packed;
> +
> +struct mei_csi {
> +	struct mei_cl_device *cldev;
> +
> +	/* command response */
> +	struct csi_notif cmd_response;
> +	/* used to wait for command response from firmware */
> +	struct completion cmd_completion;
> +
> +	/* work element used to handle firmware event */
> +	struct work_struct event_work;
> +
> +	/* privacy status */
> +	enum ivsc_privacy_status status;
> +	/* privacy callback */
> +	void (*callback)(void *, enum ivsc_privacy_status);
> +	/* privacy callback runtime context */
> +	void *context;
> +};
> +
> +/* only one for now */
> +static struct mei_csi *csi;
> +/* lock used to prevent multiple call to csi */
> +static DEFINE_MUTEX(csi_mutex);
> +
> +/* send a command to firmware and mutex must be held by caller */
> +static int mei_csi_send(u8 *buf, size_t len)
> +{
> +	struct csi_cmd *cmd = (struct csi_cmd *)buf;
> +	int ret;
> +
> +	reinit_completion(&csi->cmd_completion);
> +
> +	ret = mei_cldev_send(csi->cldev, buf, len);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = wait_for_completion_killable_timeout(&csi->cmd_completion,
> +						   CSI_CMD_TIMEOUT);
> +	if (ret < 0) {
> +		goto out;
> +	} else if (!ret) {
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +
> +	/* command response status */
> +	ret = csi->cmd_response.status;
> +	if (ret) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	if (csi->cmd_response.cmd_id != cmd->cmd_id)
> +		ret = -EINVAL;
> +
> +out:
> +	return ret;
> +}
> +
> +int csi_set_link_owner(enum csi_link_owner owner,
> +		       void (*callback)(void *, enum ivsc_privacy_status),
> +		       void *context)
> +{
> +	struct csi_cmd cmd = { 0 };
> +	size_t cmd_size;
> +	int ret;
> +
> +	cmd.cmd_id = CSI_SET_OWNER;
> +	cmd.param.param = owner;
> +	cmd_size = sizeof(cmd.cmd_id) + sizeof(cmd.param.param);

You could initialise these in variable declaration.

> +
> +	mutex_lock(&csi_mutex);
> +	if (unlikely(!csi)) {
> +		mutex_unlock(&csi_mutex);
> +		return -EAGAIN;
> +	}
> +
> +	ret = mei_csi_send((u8 *)&cmd, cmd_size);
> +
> +	/*
> +	 * cancel possible event work and wait for it to finish
> +	 * to make sure no work running for the ongoing changes
> +	 * to callback and context.
> +	 */
> +	cancel_work_sync(&csi->event_work);
> +	csi->callback = callback;
> +	csi->context = context;
> +	mutex_unlock(&csi_mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_NS_GPL(csi_set_link_owner, IVSC);
> +
> +int csi_set_link_cfg(u32 nr_of_lanes, u64 link_freq)
> +{
> +	struct csi_cmd cmd = { 0 };
> +	size_t cmd_size;
> +	int ret;
> +
> +	cmd.cmd_id = CSI_SET_CONF;
> +	cmd.param.conf.nr_of_lanes = nr_of_lanes;
> +	cmd.param.conf.link_freq = CSI_LINK_FREQ(link_freq);
> +	cmd_size = sizeof(cmd.cmd_id) + sizeof(cmd.param.conf);
> +
> +	mutex_lock(&csi_mutex);
> +	if (unlikely(!csi)) {
> +		mutex_unlock(&csi_mutex);
> +		return -EAGAIN;
> +	}
> +
> +	ret = mei_csi_send((u8 *)&cmd, cmd_size);
> +	/*
> +	 * wait configuration ready if download success. placing
> +	 * delay under mutex is to make sure current command flow
> +	 * completed before starting a possible new one.
> +	 */
> +	if (!ret)
> +		msleep(CSI_FW_READY_DELAY_MS);
> +	mutex_unlock(&csi_mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_NS_GPL(csi_set_link_cfg, IVSC);
> +
> +/* event handling routine */
> +static void mei_csi_event_work(struct work_struct *work)
> +{
> +	if (csi->callback)
> +		csi->callback(csi->context, READ_ONCE(csi->status));
> +}
> +
> +/* callback for receive */
> +static void mei_csi_rx(struct mei_cl_device *cldev)
> +{
> +	struct csi_notif notif = { 0 };
> +	int ret;
> +
> +	ret = mei_cldev_recv(cldev, (u8 *)&notif, sizeof(notif));
> +	if (ret < 0) {
> +		dev_err(&cldev->dev, "recv error: %d\n", ret);
> +		return;
> +	}
> +
> +	switch (notif.cmd_id) {
> +	case CSI_PRIVACY_NOTIF:
> +		if (notif.cont.cont < IVSC_PRIVACY_MAX) {
> +			WRITE_ONCE(csi->status, notif.cont.cont);
> +
> +			schedule_work(&csi->event_work);
> +		}
> +		break;
> +	case CSI_SET_OWNER:
> +	case CSI_SET_CONF:
> +		memcpy(&csi->cmd_response, &notif, ret);
> +
> +		complete(&csi->cmd_completion);
> +		break;
> +	default:
> +		break;
> +	}
> +}
> +
> +static int mei_csi_probe(struct mei_cl_device *cldev,
> +			 const struct mei_cl_device_id *id)
> +{
> +	int ret;
> +
> +	mutex_lock(&csi_mutex);
> +	/*
> +	 * only instance is possible in the current hardware,
> +	 * but adding protection for future hardware.
> +	 */
> +	if (csi) {
> +		ret = -EBUSY;
> +		goto err_unlock;
> +	}
> +
> +	csi = kzalloc(sizeof(*csi), GFP_KERNEL);

How do you know the MEI CSI and the MEI ACE devices are related to a given
camera sensor? I'd expect this information to come from system firmware but
I don't see this being done in this patchset.

Ideally there should be also a way to obtain the appropriate MEI CSI and
MEI ACE devices without assuming there's a single one in the system.

> +	if (!csi) {
> +		ret = -ENOMEM;
> +		goto err_unlock;
> +	}
> +
> +	csi->cldev = cldev;
> +	init_completion(&csi->cmd_completion);
> +	INIT_WORK(&csi->event_work, mei_csi_event_work);
> +
> +	mei_cldev_set_drvdata(cldev, csi);
> +
> +	ret = mei_cldev_enable(cldev);
> +	if (ret < 0) {
> +		dev_err(&cldev->dev, "mei_cldev_enable failed: %d\n", ret);
> +		goto err_free;
> +	}
> +
> +	ret = mei_cldev_register_rx_cb(cldev, mei_csi_rx);
> +	if (ret) {
> +		dev_err(&cldev->dev, "event cb registration failed: %d\n", ret);
> +		goto err_disable;
> +	}
> +	mutex_unlock(&csi_mutex);
> +
> +	return 0;
> +
> +err_disable:
> +	mei_cldev_disable(cldev);
> +
> +err_free:
> +	kfree(csi);
> +	/* disable csi */
> +	csi = NULL;
> +
> +err_unlock:
> +	mutex_unlock(&csi_mutex);
> +
> +	return ret;
> +}
> +
> +static void mei_csi_remove(struct mei_cl_device *cldev)
> +{
> +	mutex_lock(&csi_mutex);
> +	/* disable mei csi client device */
> +	mei_cldev_disable(cldev);
> +
> +	/* cancel event work and wait for it to finish */
> +	cancel_work_sync(&csi->event_work);
> +
> +	kfree(csi);
> +	/* disable csi */
> +	csi = NULL;
> +	mutex_unlock(&csi_mutex);
> +}
> +
> +#define MEI_CSI_UUID UUID_LE(0x92335FCF, 0x3203, 0x4472, \
> +			     0xAF, 0x93, 0x7b, 0x44, 0x53, 0xAC, 0x29, 0xDA)
> +
> +static const struct mei_cl_device_id mei_csi_tbl[] = {
> +	{ MEI_CSI_DRIVER_NAME, MEI_CSI_UUID, MEI_CL_VERSION_ANY },
> +
> +	/* required last entry */
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(mei, mei_csi_tbl);
> +
> +static struct mei_cl_driver mei_csi_driver = {
> +	.id_table = mei_csi_tbl,
> +	.name = MEI_CSI_DRIVER_NAME,
> +
> +	.probe = mei_csi_probe,
> +	.remove = mei_csi_remove,
> +};
> +
> +module_mei_cl_driver(mei_csi_driver);
> +
> +MODULE_AUTHOR("Wentong Wu <wentong.wu@...el.com>");
> +MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@...el.com>");
> +MODULE_DESCRIPTION("Device driver for IVSC CSI");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/media/pci/intel/ivsc/mei_csi.h b/drivers/media/pci/intel/ivsc/mei_csi.h
> new file mode 100644
> index 000000000000..0cc51e6a5250
> --- /dev/null
> +++ b/drivers/media/pci/intel/ivsc/mei_csi.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2023 Intel Corporation. All rights reserved.
> + * Intel Visual Sensing Controller CSI external interface
> + */
> +
> +#ifndef _MEI_CSI_H_
> +#define _MEI_CSI_H_
> +
> +#include <linux/ivsc.h>
> +
> +/* CSI-2 link ownership definition */
> +enum csi_link_owner {
> +	CSI_LINK_IVSC,
> +	CSI_LINK_HOST,
> +};
> +
> +#if IS_ENABLED(CONFIG_INTEL_VSC)
> +/*
> + * @brief set CSI-2 link ownership
> + *
> + * @param owner The csi ownership being set
> + * @param callback The pointer of privacy callback being set
> + * @param context Privacy callback runtime context
> + *
> + * @return 0 on success, negative on failure
> + */
> +int csi_set_link_owner(enum csi_link_owner owner,
> +		       void (*callback)(void *, enum ivsc_privacy_status),
> +		       void *context);
> +
> +/*
> + * @brief configure CSI-2 link between host and IVSC
> + * with provided parameters
> + *
> + * @param nr_of_lanes The number of data lanes being used
> + * on the CSI-2 link
> + * @param link_freq The frequency being set on the CSI-2 link
> + *
> + * @return 0 on success, negative on failure
> + */
> +int csi_set_link_cfg(u32 nr_of_lanes, u64 link_freq);
> +
> +#else
> +static inline
> +int csi_set_link_owner(enum csi_link_owner owner,
> +		       void (*callback)(void *, enum ivsc_privacy_status),
> +		       void *context)
> +{
> +	return 0;
> +}
> +
> +static inline int csi_set_link_cfg(u32 nr_of_lanes, u64 link_freq)
> +{
> +	return 0;
> +}
> +
> +#endif
> +
> +#endif
> diff --git a/include/linux/ivsc.h b/include/linux/ivsc.h
> new file mode 100644
> index 000000000000..6572ca4f340c
> --- /dev/null
> +++ b/include/linux/ivsc.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2023 Intel Corporation. All rights reserved.
> + * Intel Visual Sensing Controller interface
> + */
> +
> +#ifndef _LINUX_IVSC_H_
> +#define _LINUX_IVSC_H_
> +
> +#include <linux/types.h>
> +
> +/* IVSC privacy status definition */
> +enum ivsc_privacy_status {
> +	IVSC_PRIVACY_OFF,
> +	IVSC_PRIVACY_ON,
> +	IVSC_PRIVACY_MAX,
> +};
> +
> +#endif

-- 
Kind regards,

Sakari Ailus

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