[linux-2.6-block.git] / drivers / watchdog / mei_wdt.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2015, Intel Corporation.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/debugfs.h>
#include <linux/completion.h>
#include <linux/watchdog.h>

#include <linux/uuid.h>
#include <linux/mei_cl_bus.h>

/*
 * iAMT Watchdog Device
 */
#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"

#define MEI_WDT_DEFAULT_TIMEOUT   120  /* seconds */
#define MEI_WDT_MIN_TIMEOUT       120  /* seconds */
#define MEI_WDT_MAX_TIMEOUT     65535  /* seconds */

/* Commands */
#define MEI_MANAGEMENT_CONTROL 0x02

/* MEI Management Control version number */
#define MEI_MC_VERSION_NUMBER  0x10

/* Sub Commands */
#define MEI_MC_START_WD_TIMER_REQ  0x13
#define MEI_MC_START_WD_TIMER_RES  0x83
#define   MEI_WDT_STATUS_SUCCESS 0
#define   MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
#define MEI_MC_STOP_WD_TIMER_REQ   0x14

/**
 * enum mei_wdt_state - internal watchdog state
 *
 * @MEI_WDT_PROBE: wd in probing stage
 * @MEI_WDT_IDLE: wd is idle and not opened
 * @MEI_WDT_START: wd was opened, start was called
 * @MEI_WDT_RUNNING: wd is expecting keep alive pings
 * @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
 * @MEI_WDT_NOT_REQUIRED: wd device is not required
 */
enum mei_wdt_state {
	MEI_WDT_PROBE,
	MEI_WDT_IDLE,
	MEI_WDT_START,
	MEI_WDT_RUNNING,
	MEI_WDT_STOPPING,
	MEI_WDT_NOT_REQUIRED,
};

static const char *mei_wdt_state_str(enum mei_wdt_state state)
{
	switch (state) {
	case MEI_WDT_PROBE:
		return "PROBE";
	case MEI_WDT_IDLE:
		return "IDLE";
	case MEI_WDT_START:
		return "START";
	case MEI_WDT_RUNNING:
		return "RUNNING";
	case MEI_WDT_STOPPING:
		return "STOPPING";
	case MEI_WDT_NOT_REQUIRED:
		return "NOT_REQUIRED";
	default:
		return "unknown";
	}
}

/**
 * struct mei_wdt - mei watchdog driver
 * @wdd: watchdog device
 *
 * @cldev: mei watchdog client device
 * @state: watchdog internal state
 * @resp_required: ping required response
 * @response: ping response completion
 * @unregister: unregister worker
 * @reg_lock: watchdog device registration lock
 * @timeout: watchdog current timeout
 *
 * @dbgfs_dir: debugfs dir entry
 */
struct mei_wdt {
	struct watchdog_device wdd;

	struct mei_cl_device *cldev;
	enum mei_wdt_state state;
	bool resp_required;
	struct completion response;
	struct work_struct unregister;
	struct mutex reg_lock;
	u16 timeout;

#if IS_ENABLED(CONFIG_DEBUG_FS)
	struct dentry *dbgfs_dir;
#endif /* CONFIG_DEBUG_FS */
};

/*
 * struct mei_mc_hdr - Management Control Command Header
 *
 * @command: Management Control (0x2)
 * @bytecount: Number of bytes in the message beyond this byte
 * @subcommand: Management Control Subcommand
 * @versionnumber: Management Control Version (0x10)
 */
struct mei_mc_hdr {
	u8 command;
	u8 bytecount;
	u8 subcommand;
	u8 versionnumber;
};

/**
 * struct mei_wdt_start_request watchdog start/ping
 *
 * @hdr: Management Control Command Header
 * @timeout: timeout value
 * @reserved: reserved (legacy)
 */
struct mei_wdt_start_request {
	struct mei_mc_hdr hdr;
	u16 timeout;
	u8 reserved[17];
} __packed;

/**
 * struct mei_wdt_start_response watchdog start/ping response
 *
 * @hdr: Management Control Command Header
 * @status: operation status
 * @wdstate: watchdog status bit mask
 */
struct mei_wdt_start_response {
	struct mei_mc_hdr hdr;
	u8 status;
	u8 wdstate;
} __packed;

/**
 * struct mei_wdt_stop_request - watchdog stop
 *
 * @hdr: Management Control Command Header
 */
struct mei_wdt_stop_request {
	struct mei_mc_hdr hdr;
} __packed;

/**
 * mei_wdt_ping - send wd start/ping command
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 on success,
 *         negative errno code on failure
 */
static int mei_wdt_ping(struct mei_wdt *wdt)
{
	struct mei_wdt_start_request req;
	const size_t req_len = sizeof(req);
	int ret;

	memset(&req, 0, req_len);
	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	req.timeout = wdt->timeout;

	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	if (ret < 0)
		return ret;

	return 0;
}

/**
 * mei_wdt_stop - send wd stop command
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 on success,
 *         negative errno code on failure
 */
static int mei_wdt_stop(struct mei_wdt *wdt)
{
	struct mei_wdt_stop_request req;
	const size_t req_len = sizeof(req);
	int ret;

	memset(&req, 0, req_len);
	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;

	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	if (ret < 0)
		return ret;

	return 0;
}

/**
 * mei_wdt_ops_start - wd start command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 on success or -ENODEV;
 */
static int mei_wdt_ops_start(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);

	wdt->state = MEI_WDT_START;
	wdd->timeout = wdt->timeout;
	return 0;
}

/**
 * mei_wdt_ops_stop - wd stop command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_ops_stop(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (wdt->state != MEI_WDT_RUNNING)
		return 0;

	wdt->state = MEI_WDT_STOPPING;

	ret = mei_wdt_stop(wdt);
	if (ret)
		return ret;

	wdt->state = MEI_WDT_IDLE;

	return 0;
}

/**
 * mei_wdt_ops_ping - wd ping command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 if success, negative errno code on failure
 */
static int mei_wdt_ops_ping(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
		return 0;

	if (wdt->resp_required)
		init_completion(&wdt->response);

	wdt->state = MEI_WDT_RUNNING;
	ret = mei_wdt_ping(wdt);
	if (ret)
		return ret;

	if (wdt->resp_required)
		ret = wait_for_completion_killable(&wdt->response);

	return ret;
}

/**
 * mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
 *
 * @wdd: watchdog device
 * @timeout: timeout value to set
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
				   unsigned int timeout)
{

	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);

	/* valid value is already checked by the caller */
	wdt->timeout = timeout;
	wdd->timeout = timeout;

	return 0;
}

static const struct watchdog_ops wd_ops = {
	.owner       = THIS_MODULE,
	.start       = mei_wdt_ops_start,
	.stop        = mei_wdt_ops_stop,
	.ping        = mei_wdt_ops_ping,
	.set_timeout = mei_wdt_ops_set_timeout,
};

/* not const as the firmware_version field need to be retrieved */
static struct watchdog_info wd_info = {
	.identity = INTEL_AMT_WATCHDOG_ID,
	.options  = WDIOF_KEEPALIVEPING |
		    WDIOF_SETTIMEOUT |
		    WDIOF_ALARMONLY,
};

/**
 * __mei_wdt_is_registered - check if wdt is registered
 *
 * @wdt: mei watchdog device
 *
 * Return: true if the wdt is registered with the watchdog subsystem
 * Locking: should be called under wdt->reg_lock
 */
static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
{
	return !!watchdog_get_drvdata(&wdt->wdd);
}

/**
 * mei_wdt_unregister - unregister from the watchdog subsystem
 *
 * @wdt: mei watchdog device
 */
static void mei_wdt_unregister(struct mei_wdt *wdt)
{
	mutex_lock(&wdt->reg_lock);

	if (__mei_wdt_is_registered(wdt)) {
		watchdog_unregister_device(&wdt->wdd);
		watchdog_set_drvdata(&wdt->wdd, NULL);
		memset(&wdt->wdd, 0, sizeof(wdt->wdd));
	}

	mutex_unlock(&wdt->reg_lock);
}

/**
 * mei_wdt_register - register with the watchdog subsystem
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_register(struct mei_wdt *wdt)
{
	struct device *dev;
	int ret;

	if (!wdt || !wdt->cldev)
		return -EINVAL;

	dev = &wdt->cldev->dev;

	mutex_lock(&wdt->reg_lock);

	if (__mei_wdt_is_registered(wdt)) {
		ret = 0;
		goto out;
	}

	wdt->wdd.info = &wd_info;
	wdt->wdd.ops = &wd_ops;
	wdt->wdd.parent = dev;
	wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
	wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
	wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;

	watchdog_set_drvdata(&wdt->wdd, wdt);
	watchdog_stop_on_reboot(&wdt->wdd);

	ret = watchdog_register_device(&wdt->wdd);
	if (ret)
		watchdog_set_drvdata(&wdt->wdd, NULL);

	wdt->state = MEI_WDT_IDLE;

out:
	mutex_unlock(&wdt->reg_lock);
	return ret;
}

static void mei_wdt_unregister_work(struct work_struct *work)
{
	struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);

	mei_wdt_unregister(wdt);
}

/**
 * mei_wdt_rx - callback for data receive
 *
 * @cldev: bus device
 */
static void mei_wdt_rx(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	struct mei_wdt_start_response res;
	const size_t res_len = sizeof(res);
	int ret;

	ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
	if (ret < 0) {
		dev_err(&cldev->dev, "failure in recv %d\n", ret);
		return;
	}

	/* Empty response can be sent on stop */
	if (ret == 0)
		return;

	if (ret < sizeof(struct mei_mc_hdr)) {
		dev_err(&cldev->dev, "recv small data %d\n", ret);
		return;
	}

	if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
	    res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
		dev_err(&cldev->dev, "wrong command received\n");
		return;
	}

	if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
		dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
			 res.hdr.subcommand,
			 mei_wdt_state_str(wdt->state),
			 wdt->state);
		return;
	}

	/* Run the unregistration in a worker as this can be
	 * run only after ping completion, otherwise the flow will
	 * deadlock on watchdog core mutex.
	 */
	if (wdt->state == MEI_WDT_RUNNING) {
		if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
			wdt->state = MEI_WDT_NOT_REQUIRED;
			schedule_work(&wdt->unregister);
		}
		goto out;
	}

	if (wdt->state == MEI_WDT_PROBE) {
		if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
			wdt->state = MEI_WDT_NOT_REQUIRED;
		} else {
			/* stop the watchdog and register watchdog device */
			mei_wdt_stop(wdt);
			mei_wdt_register(wdt);
		}
		return;
	}

	dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
			 mei_wdt_state_str(wdt->state), wdt->state);

out:
	if (!completion_done(&wdt->response))
		complete(&wdt->response);
}

/*
 * mei_wdt_notif - callback for event notification
 *
 * @cldev: bus device
 */
static void mei_wdt_notif(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);

	if (wdt->state != MEI_WDT_NOT_REQUIRED)
		return;

	mei_wdt_register(wdt);
}

#if IS_ENABLED(CONFIG_DEBUG_FS)

static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
					size_t cnt, loff_t *ppos)
{
	struct mei_wdt *wdt = file->private_data;
	const size_t bufsz = 32;
	char buf[32];
	ssize_t pos;

	mutex_lock(&wdt->reg_lock);
	pos = scnprintf(buf, bufsz, "%s\n",
		__mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
	mutex_unlock(&wdt->reg_lock);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
}

static const struct file_operations dbgfs_fops_activation = {
	.open    = simple_open,
	.read    = mei_dbgfs_read_activation,
	.llseek  = generic_file_llseek,
};

static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
				    size_t cnt, loff_t *ppos)
{
	struct mei_wdt *wdt = file->private_data;
	char buf[32];
	ssize_t pos;

	pos = scnprintf(buf, sizeof(buf), "state: %s\n",
			mei_wdt_state_str(wdt->state));

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
}

static const struct file_operations dbgfs_fops_state = {
	.open = simple_open,
	.read = mei_dbgfs_read_state,
	.llseek = generic_file_llseek,
};

static void dbgfs_unregister(struct mei_wdt *wdt)
{
	debugfs_remove_recursive(wdt->dbgfs_dir);
	wdt->dbgfs_dir = NULL;
}

static void dbgfs_register(struct mei_wdt *wdt)
{
	struct dentry *dir;

	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
	wdt->dbgfs_dir = dir;

	debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);

	debugfs_create_file("activation", S_IRUSR, dir, wdt,
			    &dbgfs_fops_activation);
}

#else

static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
static inline void dbgfs_register(struct mei_wdt *wdt) {}
#endif /* CONFIG_DEBUG_FS */

static int mei_wdt_probe(struct mei_cl_device *cldev,
			 const struct mei_cl_device_id *id)
{
	struct mei_wdt *wdt;
	int ret;

	wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
	if (!wdt)
		return -ENOMEM;

	wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
	wdt->state = MEI_WDT_PROBE;
	wdt->cldev = cldev;
	wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
	mutex_init(&wdt->reg_lock);
	init_completion(&wdt->response);
	INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);

	mei_cldev_set_drvdata(cldev, wdt);

	ret = mei_cldev_enable(cldev);
	if (ret < 0) {
		dev_err(&cldev->dev, "Could not enable cl device\n");
		goto err_out;
	}

	ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
	if (ret) {
		dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
		goto err_disable;
	}

	ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
	/* on legacy devices notification is not supported
	 */
	if (ret && ret != -EOPNOTSUPP) {
		dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
		goto err_disable;
	}

	wd_info.firmware_version = mei_cldev_ver(cldev);

	if (wdt->resp_required)
		ret = mei_wdt_ping(wdt);
	else
		ret = mei_wdt_register(wdt);

	if (ret)
		goto err_disable;

	dbgfs_register(wdt);

	return 0;

err_disable:
	mei_cldev_disable(cldev);

err_out:
	kfree(wdt);

	return ret;
}

static int mei_wdt_remove(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);

	/* Free the caller in case of fw initiated or unexpected reset */
	if (!completion_done(&wdt->response))
		complete(&wdt->response);

	cancel_work_sync(&wdt->unregister);

	mei_wdt_unregister(wdt);

	mei_cldev_disable(cldev);

	dbgfs_unregister(wdt);

	kfree(wdt);

	return 0;
}

#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
			    0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)

static const struct mei_cl_device_id mei_wdt_tbl[] = {
	{ .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
	/* required last entry */
	{ }
};
MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);

static struct mei_cl_driver mei_wdt_driver = {
	.id_table = mei_wdt_tbl,
	.name = KBUILD_MODNAME,

	.probe = mei_wdt_probe,
	.remove = mei_wdt_remove,
};

module_mei_cl_driver(mei_wdt_driver);

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");
Commit	Line	Data
2e62c498	1	// SPDX-License-Identifier: GPL-2.0
222818c3 TW	2	/*
	3	* Intel Management Engine Interface (Intel MEI) Linux driver
	4	* Copyright (c) 2015, Intel Corporation.
222818c3 TW	5	*/
	6
	7	#include <linux/module.h>
	8	#include <linux/slab.h>
	9	#include <linux/interrupt.h>
c9cf20ee	10	#include <linux/debugfs.h>
7a23f80e	11	#include <linux/completion.h>
222818c3 TW	12	#include <linux/watchdog.h>
	13
	14	#include <linux/uuid.h>
	15	#include <linux/mei_cl_bus.h>
	16
	17	/*
	18	* iAMT Watchdog Device
	19	*/
	20	#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"
	21
	22	#define MEI_WDT_DEFAULT_TIMEOUT 120 /* seconds */
	23	#define MEI_WDT_MIN_TIMEOUT 120 /* seconds */
	24	#define MEI_WDT_MAX_TIMEOUT 65535 /* seconds */
	25
	26	/* Commands */
	27	#define MEI_MANAGEMENT_CONTROL 0x02
	28
	29	/* MEI Management Control version number */
	30	#define MEI_MC_VERSION_NUMBER 0x10
	31
	32	/* Sub Commands */
	33	#define MEI_MC_START_WD_TIMER_REQ 0x13
7a23f80e TW	34	#define MEI_MC_START_WD_TIMER_RES 0x83
	35	#define MEI_WDT_STATUS_SUCCESS 0
	36	#define MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
222818c3 TW	37	#define MEI_MC_STOP_WD_TIMER_REQ 0x14
	38
	39	/**
	40	* enum mei_wdt_state - internal watchdog state
	41	*
7a23f80e	42	* @MEI_WDT_PROBE: wd in probing stage
222818c3 TW	43	* @MEI_WDT_IDLE: wd is idle and not opened
	44	* @MEI_WDT_START: wd was opened, start was called
	45	* @MEI_WDT_RUNNING: wd is expecting keep alive pings
	46	* @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
7a23f80e	47	* @MEI_WDT_NOT_REQUIRED: wd device is not required
222818c3 TW	48	*/
222818c3 TW	49	enum mei_wdt_state {
7a23f80e	50	MEI_WDT_PROBE,
222818c3 TW	51	MEI_WDT_IDLE,
	52	MEI_WDT_START,
	53	MEI_WDT_RUNNING,
	54	MEI_WDT_STOPPING,
7a23f80e	55	MEI_WDT_NOT_REQUIRED,
222818c3 TW	56	};
222818c3 TW	57
c9cf20ee TW	58	static const char *mei_wdt_state_str(enum mei_wdt_state state)
	59	{
	60	switch (state) {
7a23f80e TW	61	case MEI_WDT_PROBE:
7a23f80e TW	62	return "PROBE";
c9cf20ee TW	63	case MEI_WDT_IDLE:
	64	return "IDLE";
	65	case MEI_WDT_START:
	66	return "START";
	67	case MEI_WDT_RUNNING:
	68	return "RUNNING";
	69	case MEI_WDT_STOPPING:
	70	return "STOPPING";
7a23f80e TW	71	case MEI_WDT_NOT_REQUIRED:
7a23f80e TW	72	return "NOT_REQUIRED";
c9cf20ee TW	73	default:
	74	return "unknown";
	75	}
	76	}
c9cf20ee	77
222818c3 TW	78	/**
	79	* struct mei_wdt - mei watchdog driver
	80	* @wdd: watchdog device
	81	*
	82	* @cldev: mei watchdog client device
	83	* @state: watchdog internal state
7a23f80e TW	84	* @resp_required: ping required response
	85	* @response: ping response completion
	86	* @unregister: unregister worker
	87	* @reg_lock: watchdog device registration lock
222818c3	88	* @timeout: watchdog current timeout
c9cf20ee TW	89	*
c9cf20ee TW	90	* @dbgfs_dir: debugfs dir entry
222818c3 TW	91	*/
	92	struct mei_wdt {
	93	struct watchdog_device wdd;
	94
	95	struct mei_cl_device *cldev;
	96	enum mei_wdt_state state;
7a23f80e TW	97	bool resp_required;
	98	struct completion response;
	99	struct work_struct unregister;
	100	struct mutex reg_lock;
222818c3	101	u16 timeout;
c9cf20ee TW	102
	103	#if IS_ENABLED(CONFIG_DEBUG_FS)
	104	struct dentry *dbgfs_dir;
	105	#endif /* CONFIG_DEBUG_FS */
222818c3 TW	106	};
	107
	108	/*
	109	* struct mei_mc_hdr - Management Control Command Header
	110	*
	111	* @command: Management Control (0x2)
	112	* @bytecount: Number of bytes in the message beyond this byte
	113	* @subcommand: Management Control Subcommand
	114	* @versionnumber: Management Control Version (0x10)
	115	*/
	116	struct mei_mc_hdr {
	117	u8 command;
	118	u8 bytecount;
	119	u8 subcommand;
	120	u8 versionnumber;
	121	};
	122
	123	/**
	124	* struct mei_wdt_start_request watchdog start/ping
	125	*
	126	* @hdr: Management Control Command Header
	127	* @timeout: timeout value
	128	* @reserved: reserved (legacy)
	129	*/
	130	struct mei_wdt_start_request {
	131	struct mei_mc_hdr hdr;
	132	u16 timeout;
	133	u8 reserved[17];
	134	} __packed;
	135
7a23f80e TW	136	/**
	137	* struct mei_wdt_start_response watchdog start/ping response
	138	*
	139	* @hdr: Management Control Command Header
	140	* @status: operation status
	141	* @wdstate: watchdog status bit mask
	142	*/
	143	struct mei_wdt_start_response {
	144	struct mei_mc_hdr hdr;
	145	u8 status;
	146	u8 wdstate;
	147	} __packed;
	148
222818c3 TW	149	/**
	150	* struct mei_wdt_stop_request - watchdog stop
	151	*
	152	* @hdr: Management Control Command Header
	153	*/
	154	struct mei_wdt_stop_request {
	155	struct mei_mc_hdr hdr;
	156	} __packed;
	157
	158	/**
	159	* mei_wdt_ping - send wd start/ping command
	160	*
	161	* @wdt: mei watchdog device
	162	*
	163	* Return: 0 on success,
	164	* negative errno code on failure
	165	*/
	166	static int mei_wdt_ping(struct mei_wdt *wdt)
	167	{
	168	struct mei_wdt_start_request req;
	169	const size_t req_len = sizeof(req);
	170	int ret;
	171
	172	memset(&req, 0, req_len);
	173	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	174	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	175	req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
	176	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	177	req.timeout = wdt->timeout;
	178
	179	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	180	if (ret < 0)
	181	return ret;
	182
	183	return 0;
	184	}
	185
	186	/**
	187	* mei_wdt_stop - send wd stop command
	188	*
	189	* @wdt: mei watchdog device
	190	*
	191	* Return: 0 on success,
	192	* negative errno code on failure
	193	*/
	194	static int mei_wdt_stop(struct mei_wdt *wdt)
	195	{
	196	struct mei_wdt_stop_request req;
	197	const size_t req_len = sizeof(req);
	198	int ret;
	199
	200	memset(&req, 0, req_len);
	201	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	202	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	203	req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
	204	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	205
	206	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	207	if (ret < 0)
	208	return ret;
	209
	210	return 0;
	211	}
	212
213	/**
214	* mei_wdt_ops_start - wd start command from the watchdog core.
215	*
216	* @wdd: watchdog device
217	*
218	* Return: 0 on success or -ENODEV;
219	*/
220	static int mei_wdt_ops_start(struct watchdog_device *wdd)
221	{
222	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
223
224	wdt->state = MEI_WDT_START;
225	wdd->timeout = wdt->timeout;
226	return 0;
227	}
228
229	/**
230	* mei_wdt_ops_stop - wd stop command from the watchdog core.
231	*
232	* @wdd: watchdog device
233	*
234	* Return: 0 if success, negative errno code for failure
235	*/
236	static int mei_wdt_ops_stop(struct watchdog_device *wdd)
237	{
238	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
239	int ret;
240
241	if (wdt->state != MEI_WDT_RUNNING)
242	return 0;
243
244	wdt->state = MEI_WDT_STOPPING;
245
246	ret = mei_wdt_stop(wdt);
247	if (ret)
248	return ret;
249
250	wdt->state = MEI_WDT_IDLE;
251
252	return 0;
253	}
254
255	/**
256	* mei_wdt_ops_ping - wd ping command from the watchdog core.
257	*
258	* @wdd: watchdog device
259	*
260	* Return: 0 if success, negative errno code on failure
261	*/
262	static int mei_wdt_ops_ping(struct watchdog_device *wdd)
263	{
264	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
265	int ret;
266
267	if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
268	return 0;
269
7a23f80e TW	270	if (wdt->resp_required)
	271	init_completion(&wdt->response);
	272
	273	wdt->state = MEI_WDT_RUNNING;
222818c3 TW	274	ret = mei_wdt_ping(wdt);
	275	if (ret)
	276	return ret;
	277
7a23f80e TW	278	if (wdt->resp_required)
7a23f80e TW	279	ret = wait_for_completion_killable(&wdt->response);
222818c3	280
7a23f80e	281	return ret;
222818c3 TW	282	}
	283
	284	/**
	285	* mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
	286	*
	287	* @wdd: watchdog device
	288	* @timeout: timeout value to set
	289	*
	290	* Return: 0 if success, negative errno code for failure
	291	*/
	292	static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
	293	unsigned int timeout)
	294	{
	295
	296	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	297
	298	/* valid value is already checked by the caller */
	299	wdt->timeout = timeout;
	300	wdd->timeout = timeout;
	301
	302	return 0;
	303	}
	304
	305	static const struct watchdog_ops wd_ops = {
	306	.owner = THIS_MODULE,
	307	.start = mei_wdt_ops_start,
	308	.stop = mei_wdt_ops_stop,
	309	.ping = mei_wdt_ops_ping,
	310	.set_timeout = mei_wdt_ops_set_timeout,
	311	};
	312
	313	/* not const as the firmware_version field need to be retrieved */
	314	static struct watchdog_info wd_info = {
	315	.identity = INTEL_AMT_WATCHDOG_ID,
	316	.options = WDIOF_KEEPALIVEPING \|
	317	WDIOF_SETTIMEOUT \|
	318	WDIOF_ALARMONLY,
	319	};
	320
7a23f80e TW	321	/**
	322	* __mei_wdt_is_registered - check if wdt is registered
	323	*
	324	* @wdt: mei watchdog device
	325	*
	326	* Return: true if the wdt is registered with the watchdog subsystem
	327	* Locking: should be called under wdt->reg_lock
	328	*/
	329	static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
	330	{
	331	return !!watchdog_get_drvdata(&wdt->wdd);
	332	}
	333
222818c3 TW	334	/**
	335	* mei_wdt_unregister - unregister from the watchdog subsystem
	336	*
	337	* @wdt: mei watchdog device
	338	*/
	339	static void mei_wdt_unregister(struct mei_wdt *wdt)
	340	{
7a23f80e TW	341	mutex_lock(&wdt->reg_lock);
	342
	343	if (__mei_wdt_is_registered(wdt)) {
	344	watchdog_unregister_device(&wdt->wdd);
	345	watchdog_set_drvdata(&wdt->wdd, NULL);
	346	memset(&wdt->wdd, 0, sizeof(wdt->wdd));
	347	}
	348
	349	mutex_unlock(&wdt->reg_lock);
222818c3 TW	350	}
	351
	352	/**
	353	* mei_wdt_register - register with the watchdog subsystem
	354	*
	355	* @wdt: mei watchdog device
	356	*
	357	* Return: 0 if success, negative errno code for failure
	358	*/
	359	static int mei_wdt_register(struct mei_wdt *wdt)
	360	{
	361	struct device *dev;
	362	int ret;
	363
	364	if (!wdt \|\| !wdt->cldev)
	365	return -EINVAL;
	366
	367	dev = &wdt->cldev->dev;
	368
7a23f80e TW	369	mutex_lock(&wdt->reg_lock);
	370
	371	if (__mei_wdt_is_registered(wdt)) {
	372	ret = 0;
	373	goto out;
	374	}
	375
222818c3 TW	376	wdt->wdd.info = &wd_info;
	377	wdt->wdd.ops = &wd_ops;
	378	wdt->wdd.parent = dev;
	379	wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
	380	wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
	381	wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
	382
	383	watchdog_set_drvdata(&wdt->wdd, wdt);
9eff1140 AU	384	watchdog_stop_on_reboot(&wdt->wdd);
9eff1140 AU	385
222818c3	386	ret = watchdog_register_device(&wdt->wdd);
2b7ebd34	387	if (ret)
222818c3	388	watchdog_set_drvdata(&wdt->wdd, NULL);
222818c3	389
7a23f80e TW	390	wdt->state = MEI_WDT_IDLE;
	391
	392	out:
	393	mutex_unlock(&wdt->reg_lock);
222818c3 TW	394	return ret;
	395	}
	396
7a23f80e TW	397	static void mei_wdt_unregister_work(struct work_struct *work)
	398	{
	399	struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
	400
	401	mei_wdt_unregister(wdt);
	402	}
	403
	404	/**
7c7a6077	405	* mei_wdt_rx - callback for data receive
7a23f80e TW	406	*
	407	* @cldev: bus device
	408	*/
7c7a6077	409	static void mei_wdt_rx(struct mei_cl_device *cldev)
7a23f80e TW	410	{
	411	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	412	struct mei_wdt_start_response res;
	413	const size_t res_len = sizeof(res);
	414	int ret;
	415
	416	ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
	417	if (ret < 0) {
	418	dev_err(&cldev->dev, "failure in recv %d\n", ret);
	419	return;
	420	}
	421
	422	/* Empty response can be sent on stop */
	423	if (ret == 0)
	424	return;
	425
	426	if (ret < sizeof(struct mei_mc_hdr)) {
	427	dev_err(&cldev->dev, "recv small data %d\n", ret);
	428	return;
	429	}
	430
	431	if (res.hdr.command != MEI_MANAGEMENT_CONTROL \|\|
	432	res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
	433	dev_err(&cldev->dev, "wrong command received\n");
	434	return;
	435	}
	436
	437	if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
	438	dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
	439	res.hdr.subcommand,
	440	mei_wdt_state_str(wdt->state),
	441	wdt->state);
	442	return;
	443	}
	444
	445	/* Run the unregistration in a worker as this can be
	446	* run only after ping completion, otherwise the flow will
	447	* deadlock on watchdog core mutex.
	448	*/
	449	if (wdt->state == MEI_WDT_RUNNING) {
	450	if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
	451	wdt->state = MEI_WDT_NOT_REQUIRED;
	452	schedule_work(&wdt->unregister);
	453	}
	454	goto out;
	455	}
	456
	457	if (wdt->state == MEI_WDT_PROBE) {
	458	if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
	459	wdt->state = MEI_WDT_NOT_REQUIRED;
	460	} else {
	461	/* stop the watchdog and register watchdog device */
	462	mei_wdt_stop(wdt);
	463	mei_wdt_register(wdt);
	464	}
	465	return;
	466	}
	467
	468	dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
	469	mei_wdt_state_str(wdt->state), wdt->state);
	470
	471	out:
	472	if (!completion_done(&wdt->response))
	473	complete(&wdt->response);
474	}
475
3a20a5c3	476	/*
7c7a6077	477	* mei_wdt_notif - callback for event notification
3a20a5c3 TW	478	*
	479	* @cldev: bus device
	480	*/
7c7a6077	481	static void mei_wdt_notif(struct mei_cl_device *cldev)
3a20a5c3 TW	482	{
	483	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	484
	485	if (wdt->state != MEI_WDT_NOT_REQUIRED)
	486	return;
	487
	488	mei_wdt_register(wdt);
	489	}
	490
c9cf20ee TW	491	#if IS_ENABLED(CONFIG_DEBUG_FS)
c9cf20ee TW	492
ad1cd720 TW	493	static ssize_t mei_dbgfs_read_activation(struct file file, char __user ubuf,
	494	size_t cnt, loff_t *ppos)
	495	{
	496	struct mei_wdt *wdt = file->private_data;
	497	const size_t bufsz = 32;
	498	char buf[32];
	499	ssize_t pos;
	500
	501	mutex_lock(&wdt->reg_lock);
	502	pos = scnprintf(buf, bufsz, "%s\n",
	503	__mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
	504	mutex_unlock(&wdt->reg_lock);
	505
	506	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
	507	}
	508
	509	static const struct file_operations dbgfs_fops_activation = {
	510	.open = simple_open,
	511	.read = mei_dbgfs_read_activation,
	512	.llseek = generic_file_llseek,
	513	};
	514
c9cf20ee TW	515	static ssize_t mei_dbgfs_read_state(struct file file, char __user ubuf,
	516	size_t cnt, loff_t *ppos)
	517	{
	518	struct mei_wdt *wdt = file->private_data;
7692a982	519	char buf[32];
c9cf20ee TW	520	ssize_t pos;
c9cf20ee TW	521
7692a982 TW	522	pos = scnprintf(buf, sizeof(buf), "state: %s\n",
7692a982 TW	523	mei_wdt_state_str(wdt->state));
c9cf20ee TW	524
	525	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
	526	}
	527
	528	static const struct file_operations dbgfs_fops_state = {
	529	.open = simple_open,
	530	.read = mei_dbgfs_read_state,
	531	.llseek = generic_file_llseek,
	532	};
	533
	534	static void dbgfs_unregister(struct mei_wdt *wdt)
	535	{
	536	debugfs_remove_recursive(wdt->dbgfs_dir);
	537	wdt->dbgfs_dir = NULL;
	538	}
	539
64079cf9	540	static void dbgfs_register(struct mei_wdt *wdt)
c9cf20ee	541	{
64079cf9	542	struct dentry *dir;
c9cf20ee TW	543
c9cf20ee TW	544	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
c9cf20ee	545	wdt->dbgfs_dir = dir;
c9cf20ee	546
64079cf9	547	debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
ad1cd720	548
64079cf9 GKH	549	debugfs_create_file("activation", S_IRUSR, dir, wdt,
64079cf9 GKH	550	&dbgfs_fops_activation);
c9cf20ee TW	551	}
	552
	553	#else
	554
	555	static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
64079cf9	556	static inline void dbgfs_register(struct mei_wdt *wdt) {}
c9cf20ee TW	557	#endif /* CONFIG_DEBUG_FS */
c9cf20ee TW	558
222818c3 TW	559	static int mei_wdt_probe(struct mei_cl_device *cldev,
	560	const struct mei_cl_device_id *id)
	561	{
	562	struct mei_wdt *wdt;
	563	int ret;
	564
	565	wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
	566	if (!wdt)
	567	return -ENOMEM;
	568
	569	wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
7a23f80e	570	wdt->state = MEI_WDT_PROBE;
222818c3	571	wdt->cldev = cldev;
7a23f80e TW	572	wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
	573	mutex_init(&wdt->reg_lock);
	574	init_completion(&wdt->response);
	575	INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
	576
222818c3 TW	577	mei_cldev_set_drvdata(cldev, wdt);
	578
	579	ret = mei_cldev_enable(cldev);
	580	if (ret < 0) {
	581	dev_err(&cldev->dev, "Could not enable cl device\n");
	582	goto err_out;
	583	}
	584
7c7a6077 AU	585	ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
	586	if (ret) {
	587	dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
	588	goto err_disable;
	589	}
3a20a5c3	590
7c7a6077	591	ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
3a20a5c3	592	/* on legacy devices notification is not supported
3a20a5c3 TW	593	*/
3a20a5c3 TW	594	if (ret && ret != -EOPNOTSUPP) {
7c7a6077	595	dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
7a23f80e TW	596	goto err_disable;
	597	}
	598
222818c3 TW	599	wd_info.firmware_version = mei_cldev_ver(cldev);
222818c3 TW	600
7a23f80e TW	601	if (wdt->resp_required)
	602	ret = mei_wdt_ping(wdt);
	603	else
	604	ret = mei_wdt_register(wdt);
	605
222818c3 TW	606	if (ret)
	607	goto err_disable;
	608
64079cf9	609	dbgfs_register(wdt);
c9cf20ee	610
222818c3 TW	611	return 0;
	612
	613	err_disable:
	614	mei_cldev_disable(cldev);
	615
	616	err_out:
	617	kfree(wdt);
	618
	619	return ret;
	620	}
	621
	622	static int mei_wdt_remove(struct mei_cl_device *cldev)
	623	{
	624	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	625
7a23f80e TW	626	/* Free the caller in case of fw initiated or unexpected reset */
	627	if (!completion_done(&wdt->response))
	628	complete(&wdt->response);
	629
	630	cancel_work_sync(&wdt->unregister);
	631
222818c3 TW	632	mei_wdt_unregister(wdt);
	633
	634	mei_cldev_disable(cldev);
	635
c9cf20ee TW	636	dbgfs_unregister(wdt);
c9cf20ee TW	637
222818c3 TW	638	kfree(wdt);
	639
	640	return 0;
	641	}
	642
	643	#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
	644	0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
	645
4cb30b04	646	static const struct mei_cl_device_id mei_wdt_tbl[] = {
7a23f80e	647	{ .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
222818c3 TW	648	/* required last entry */
	649	{ }
	650	};
	651	MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
	652
	653	static struct mei_cl_driver mei_wdt_driver = {
	654	.id_table = mei_wdt_tbl,
	655	.name = KBUILD_MODNAME,
	656
	657	.probe = mei_wdt_probe,
	658	.remove = mei_wdt_remove,
	659	};
	660
b2a2f708	661	module_mei_cl_driver(mei_wdt_driver);
222818c3 TW	662
222818c3 TW	663	MODULE_AUTHOR("Intel Corporation");
2e62c498	664	MODULE_LICENSE("GPL v2");
222818c3	665	MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");