drivers/media/pci/intel/ivsc/mei_ace.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2023 Intel Corporation. All rights reserved.
 * Intel Visual Sensing Controller ACE Linux driver
 */

/*
 * To set ownership of camera sensor, there is specific command, which
 * is sent via MEI protocol. That's a two-step scheme where the firmware
 * first acks receipt of the command and later responses the command was
 * executed. The command sending function uses "completion" as the
 * synchronization mechanism. The notification for command is received
 * via a mei callback which wakes up the caller. There can be only one
 * outstanding command at a time.
 *
 * The power line of camera sensor is directly connected to IVSC instead
 * of host, when camera sensor ownership is switched to host, sensor is
 * already powered up by firmware.
 */

#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/mei_cl_bus.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/uuid.h>
#include <linux/workqueue.h>

/* indicating driver message */
#define	ACE_DRV_MSG		1
/* indicating set command */
#define	ACE_CMD_SET		4
/* command timeout determined experimentally */
#define	ACE_CMD_TIMEOUT		(5 * HZ)
/* indicating the first command block */
#define	ACE_CMD_INIT_BLOCK	1
/* indicating the last command block */
#define	ACE_CMD_FINAL_BLOCK	1
/* size of camera status notification content */
#define	ACE_CAMERA_STATUS_SIZE	5

/* UUID used to get firmware id */
#define ACE_GET_FW_ID_UUID UUID_LE(0x6167DCFB, 0x72F1, 0x4584, 0xBF, \
				   0xE3, 0x84, 0x17, 0x71, 0xAA, 0x79, 0x0B)

/* UUID used to get csi device */
#define MEI_CSI_UUID UUID_LE(0x92335FCF, 0x3203, 0x4472, \
			     0xAF, 0x93, 0x7b, 0x44, 0x53, 0xAC, 0x29, 0xDA)

/* identify firmware event type */
enum ace_event_type {
	/* firmware ready */
	ACE_FW_READY = 0x8,

	/* command response */
	ACE_CMD_RESPONSE = 0x10,
};

/* identify camera sensor ownership */
enum ace_camera_owner {
	ACE_CAMERA_IVSC,
	ACE_CAMERA_HOST,
};

/* identify the command id supported by firmware IPC */
enum ace_cmd_id {
	/* used to switch camera sensor to host */
	ACE_SWITCH_CAMERA_TO_HOST = 0x13,

	/* used to switch camera sensor to IVSC */
	ACE_SWITCH_CAMERA_TO_IVSC = 0x14,

	/* used to get firmware id */
	ACE_GET_FW_ID = 0x1A,
};

/* ACE command header structure */
struct ace_cmd_hdr {
	u32 firmware_id : 16;
	u32 instance_id : 8;
	u32 type : 5;
	u32 rsp : 1;
	u32 msg_tgt : 1;
	u32 _hw_rsvd_1 : 1;
	u32 param_size : 20;
	u32 cmd_id : 8;
	u32 final_block : 1;
	u32 init_block : 1;
	u32 _hw_rsvd_2 : 2;
} __packed;

/* ACE command parameter structure */
union ace_cmd_param {
	uuid_le uuid;
	u32 param;
};

/* ACE command structure */
struct ace_cmd {
	struct ace_cmd_hdr hdr;
	union ace_cmd_param param;
} __packed;

/* ACE notification header */
union ace_notif_hdr {
	struct _confirm {
		u32 status : 24;
		u32 type : 5;
		u32 rsp : 1;
		u32 msg_tgt : 1;
		u32 _hw_rsvd_1 : 1;
		u32 param_size : 20;
		u32 cmd_id : 8;
		u32 final_block : 1;
		u32 init_block : 1;
		u32 _hw_rsvd_2 : 2;
	} __packed ack;

	struct _event {
		u32 rsvd1 : 16;
		u32 event_type : 8;
		u32 type : 5;
		u32 ack : 1;
		u32 msg_tgt : 1;
		u32 _hw_rsvd_1 : 1;
		u32 rsvd2 : 30;
		u32 _hw_rsvd_2 : 2;
	} __packed event;

	struct _response {
		u32 event_id : 16;
		u32 notif_type : 8;
		u32 type : 5;
		u32 rsp : 1;
		u32 msg_tgt : 1;
		u32 _hw_rsvd_1 : 1;
		u32 event_data_size : 16;
		u32 request_target : 1;
		u32 request_type : 5;
		u32 cmd_id : 8;
		u32 _hw_rsvd_2 : 2;
	} __packed response;
};

/* ACE notification content */
union ace_notif_cont {
	u16 firmware_id;
	u8 state_notif;
	u8 camera_status[ACE_CAMERA_STATUS_SIZE];
};

/* ACE notification structure */
struct ace_notif {
	union ace_notif_hdr hdr;
	union ace_notif_cont cont;
} __packed;

struct mei_ace {
	struct mei_cl_device *cldev;

	/* command ack */
	struct ace_notif cmd_ack;
	/* command response */
	struct ace_notif cmd_response;
	/* used to wait for command ack and response */
	struct completion cmd_completion;
	/* lock used to prevent multiple call to send command */
	struct mutex lock;

	/* used to construct command */
	u16 firmware_id;

	struct device *csi_dev;

	/* runtime PM link from ace to csi */
	struct device_link *csi_link;

	struct work_struct work;
};

static inline void init_cmd_hdr(struct ace_cmd_hdr *hdr)
{
	memset(hdr, 0, sizeof(struct ace_cmd_hdr));

	hdr->type = ACE_CMD_SET;
	hdr->msg_tgt = ACE_DRV_MSG;
	hdr->init_block = ACE_CMD_INIT_BLOCK;
	hdr->final_block = ACE_CMD_FINAL_BLOCK;
}

static int construct_command(struct mei_ace *ace, struct ace_cmd *cmd,
			     enum ace_cmd_id cmd_id)
{
	union ace_cmd_param *param = &cmd->param;
	struct ace_cmd_hdr *hdr = &cmd->hdr;

	init_cmd_hdr(hdr);

	hdr->cmd_id = cmd_id;
	switch (cmd_id) {
	case ACE_GET_FW_ID:
		param->uuid = ACE_GET_FW_ID_UUID;
		hdr->param_size = sizeof(param->uuid);
		break;
	case ACE_SWITCH_CAMERA_TO_IVSC:
		param->param = 0;
		hdr->firmware_id = ace->firmware_id;
		hdr->param_size = sizeof(param->param);
		break;
	case ACE_SWITCH_CAMERA_TO_HOST:
		hdr->firmware_id = ace->firmware_id;
		break;
	default:
		return -EINVAL;
	}

	return hdr->param_size + sizeof(cmd->hdr);
}

/* send command to firmware */
static int mei_ace_send(struct mei_ace *ace, struct ace_cmd *cmd,
			size_t len, bool only_ack)
{
	union ace_notif_hdr *resp_hdr = &ace->cmd_response.hdr;
	union ace_notif_hdr *ack_hdr = &ace->cmd_ack.hdr;
	struct ace_cmd_hdr *cmd_hdr = &cmd->hdr;
	int ret;

	mutex_lock(&ace->lock);

	reinit_completion(&ace->cmd_completion);

	ret = mei_cldev_send(ace->cldev, (u8 *)cmd, len);
	if (ret < 0)
		goto out;

	ret = wait_for_completion_killable_timeout(&ace->cmd_completion,
						   ACE_CMD_TIMEOUT);
	if (ret < 0) {
		goto out;
	} else if (!ret) {
		ret = -ETIMEDOUT;
		goto out;
	}

	if (ack_hdr->ack.cmd_id != cmd_hdr->cmd_id) {
		ret = -EINVAL;
		goto out;
	}

	/* command ack status */
	ret = ack_hdr->ack.status;
	if (ret) {
		ret = -EIO;
		goto out;
	}

	if (only_ack)
		goto out;

	ret = wait_for_completion_killable_timeout(&ace->cmd_completion,
						   ACE_CMD_TIMEOUT);
	if (ret < 0) {
		goto out;
	} else if (!ret) {
		ret = -ETIMEDOUT;
		goto out;
	} else {
		ret = 0;
	}

	if (resp_hdr->response.cmd_id != cmd_hdr->cmd_id)
		ret = -EINVAL;

out:
	mutex_unlock(&ace->lock);

	return ret;
}

static int ace_set_camera_owner(struct mei_ace *ace,
				enum ace_camera_owner owner)
{
	enum ace_cmd_id cmd_id;
	struct ace_cmd cmd;
	int cmd_size;
	int ret;

	if (owner == ACE_CAMERA_IVSC)
		cmd_id = ACE_SWITCH_CAMERA_TO_IVSC;
	else
		cmd_id = ACE_SWITCH_CAMERA_TO_HOST;

	cmd_size = construct_command(ace, &cmd, cmd_id);
	if (cmd_size >= 0)
		ret = mei_ace_send(ace, &cmd, cmd_size, false);
	else
		ret = cmd_size;

	return ret;
}

/* the first command downloaded to firmware */
static inline int ace_get_firmware_id(struct mei_ace *ace)
{
	struct ace_cmd cmd;
	int cmd_size;
	int ret;

	cmd_size = construct_command(ace, &cmd, ACE_GET_FW_ID);
	if (cmd_size >= 0)
		ret = mei_ace_send(ace, &cmd, cmd_size, true);
	else
		ret = cmd_size;

	return ret;
}

static void handle_command_response(struct mei_ace *ace,
				    struct ace_notif *resp, int len)
{
	union ace_notif_hdr *hdr = &resp->hdr;

	switch (hdr->response.cmd_id) {
	case ACE_SWITCH_CAMERA_TO_IVSC:
	case ACE_SWITCH_CAMERA_TO_HOST:
		memcpy(&ace->cmd_response, resp, len);
		complete(&ace->cmd_completion);
		break;
	case ACE_GET_FW_ID:
		break;
	default:
		break;
	}
}

static void handle_command_ack(struct mei_ace *ace,
			       struct ace_notif *ack, int len)
{
	union ace_notif_hdr *hdr = &ack->hdr;

	switch (hdr->ack.cmd_id) {
	case ACE_GET_FW_ID:
		ace->firmware_id = ack->cont.firmware_id;
		fallthrough;
	case ACE_SWITCH_CAMERA_TO_IVSC:
	case ACE_SWITCH_CAMERA_TO_HOST:
		memcpy(&ace->cmd_ack, ack, len);
		complete(&ace->cmd_completion);
		break;
	default:
		break;
	}
}

/* callback for receive */
static void mei_ace_rx(struct mei_cl_device *cldev)
{
	struct mei_ace *ace = mei_cldev_get_drvdata(cldev);
	struct ace_notif event;
	union ace_notif_hdr *hdr = &event.hdr;
	int ret;

	ret = mei_cldev_recv(cldev, (u8 *)&event, sizeof(event));
	if (ret < 0) {
		dev_err(&cldev->dev, "recv error: %d\n", ret);
		return;
	}

	if (hdr->event.ack) {
		handle_command_ack(ace, &event, ret);
		return;
	}

	switch (hdr->event.event_type) {
	case ACE_CMD_RESPONSE:
		handle_command_response(ace, &event, ret);
		break;
	case ACE_FW_READY:
		/*
		 * firmware ready notification sent to driver
		 * after HECI client connected with firmware.
		 */
		dev_dbg(&cldev->dev, "firmware ready\n");
		break;
	default:
		break;
	}
}

static int mei_ace_setup_dev_link(struct mei_ace *ace)
{
	struct device *dev = &ace->cldev->dev;
	uuid_le uuid = MEI_CSI_UUID;
	struct device *csi_dev;
	char name[64];
	int ret;

	snprintf(name, sizeof(name), "%s-%pUl", dev_name(dev->parent), &uuid);

	csi_dev = device_find_child_by_name(dev->parent, name);
	if (!csi_dev) {
		ret = -EPROBE_DEFER;
		goto err;
	} else if (!dev_fwnode(csi_dev)) {
		ret = -EPROBE_DEFER;
		goto err_put;
	}

	/* setup link between mei_ace and mei_csi */
	ace->csi_link = device_link_add(csi_dev, dev, DL_FLAG_PM_RUNTIME |
					DL_FLAG_RPM_ACTIVE | DL_FLAG_STATELESS);
	if (!ace->csi_link) {
		ret = -EINVAL;
		dev_err(dev, "failed to link to %s\n", dev_name(csi_dev));
		goto err_put;
	}

	ace->csi_dev = csi_dev;

	return 0;

err_put:
	put_device(csi_dev);

err:
	return ret;
}

/* switch camera to host before probe sensor device */
static void mei_ace_post_probe_work(struct work_struct *work)
{
	struct acpi_device *adev;
	struct mei_ace *ace;
	struct device *dev;
	int ret;

	ace = container_of(work, struct mei_ace, work);
	dev = &ace->cldev->dev;

	ret = ace_set_camera_owner(ace, ACE_CAMERA_HOST);
	if (ret) {
		dev_err(dev, "switch camera to host failed: %d\n", ret);
		return;
	}

	adev = ACPI_COMPANION(dev->parent);
	if (!adev)
		return;

	acpi_dev_clear_dependencies(adev);
}

static int mei_ace_probe(struct mei_cl_device *cldev,
			 const struct mei_cl_device_id *id)
{
	struct device *dev = &cldev->dev;
	struct mei_ace *ace;
	int ret;

	ace = devm_kzalloc(dev, sizeof(struct mei_ace), GFP_KERNEL);
	if (!ace)
		return -ENOMEM;

	ace->cldev = cldev;
	mutex_init(&ace->lock);
	init_completion(&ace->cmd_completion);
	INIT_WORK(&ace->work, mei_ace_post_probe_work);

	mei_cldev_set_drvdata(cldev, ace);

	ret = mei_cldev_enable(cldev);
	if (ret < 0) {
		dev_err(dev, "mei_cldev_enable failed: %d\n", ret);
		goto destroy_mutex;
	}

	ret = mei_cldev_register_rx_cb(cldev, mei_ace_rx);
	if (ret) {
		dev_err(dev, "event cb registration failed: %d\n", ret);
		goto err_disable;
	}

	ret = ace_get_firmware_id(ace);
	if (ret) {
		dev_err(dev, "get firmware id failed: %d\n", ret);
		goto err_disable;
	}

	pm_runtime_set_active(dev);
	pm_runtime_enable(dev);

	ret = mei_ace_setup_dev_link(ace);
	if (ret)
		goto disable_pm;

	schedule_work(&ace->work);

	return 0;

disable_pm:
	pm_runtime_disable(dev);
	pm_runtime_set_suspended(dev);

err_disable:
	mei_cldev_disable(cldev);

destroy_mutex:
	mutex_destroy(&ace->lock);

	return ret;
}

static void mei_ace_remove(struct mei_cl_device *cldev)
{
	struct mei_ace *ace = mei_cldev_get_drvdata(cldev);

	cancel_work_sync(&ace->work);

	device_link_del(ace->csi_link);
	put_device(ace->csi_dev);

	pm_runtime_disable(&cldev->dev);
	pm_runtime_set_suspended(&cldev->dev);

	ace_set_camera_owner(ace, ACE_CAMERA_IVSC);

	mutex_destroy(&ace->lock);
}

static int __maybe_unused mei_ace_runtime_suspend(struct device *dev)
{
	struct mei_ace *ace = dev_get_drvdata(dev);

	return ace_set_camera_owner(ace, ACE_CAMERA_IVSC);
}

static int __maybe_unused mei_ace_runtime_resume(struct device *dev)
{
	struct mei_ace *ace = dev_get_drvdata(dev);

	return ace_set_camera_owner(ace, ACE_CAMERA_HOST);
}

static const struct dev_pm_ops mei_ace_pm_ops = {
	SET_RUNTIME_PM_OPS(mei_ace_runtime_suspend,
			   mei_ace_runtime_resume, NULL)
};

#define MEI_ACE_UUID UUID_LE(0x5DB76CF6, 0x0A68, 0x4ED6, \
			     0x9B, 0x78, 0x03, 0x61, 0x63, 0x5E, 0x24, 0x47)

static const struct mei_cl_device_id mei_ace_tbl[] = {
	{ .uuid = MEI_ACE_UUID, .version = MEI_CL_VERSION_ANY },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(mei, mei_ace_tbl);

static struct mei_cl_driver mei_ace_driver = {
	.id_table = mei_ace_tbl,
	.name = KBUILD_MODNAME,

	.probe = mei_ace_probe,
	.remove = mei_ace_remove,

	.driver = {
		.pm = &mei_ace_pm_ops,
	},
};

module_mei_cl_driver(mei_ace_driver);

MODULE_AUTHOR("Wentong Wu <wentong.wu@intel.com>");
MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@intel.com>");
MODULE_DESCRIPTION("Device driver for IVSC ACE");
MODULE_LICENSE("GPL");