[deliverable/linux.git] / drivers / watchdog / mei_wdt.c

/*
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 */

#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);
	ret = watchdog_register_device(&wdt->wdd);
	if (ret) {
		dev_err(dev, "unable to register watchdog device = %d.\n", 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_event_rx - callback for data receive
 *
 * @cldev: bus device
 */
static void mei_wdt_event_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_notify_event - callback for event notification
 *
 * @cldev: bus device
 */
static void mei_wdt_notify_event(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);
}

/**
 * mei_wdt_event - callback for event receive
 *
 * @cldev: bus device
 * @events: event mask
 * @context: callback context
 */
static void mei_wdt_event(struct mei_cl_device *cldev,
			  u32 events, void *context)
{
	if (events & BIT(MEI_CL_EVENT_RX))
		mei_wdt_event_rx(cldev);

	if (events & BIT(MEI_CL_EVENT_NOTIF))
		mei_wdt_notify_event(cldev);
}

#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;
	const size_t bufsz = 32;
	char buf[bufsz];
	ssize_t pos;

	pos = scnprintf(buf, bufsz, "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 int dbgfs_register(struct mei_wdt *wdt)
{
	struct dentry *dir, *f;

	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
	if (!dir)
		return -ENOMEM;

	wdt->dbgfs_dir = dir;
	f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
	if (!f)
		goto err;

	f = debugfs_create_file("activation",  S_IRUSR,
				dir, wdt, &dbgfs_fops_activation);
	if (!f)
		goto err;

	return 0;
err:
	dbgfs_unregister(wdt);
	return -ENODEV;
}

#else

static inline void dbgfs_unregister(struct mei_wdt *wdt) {}

static inline int dbgfs_register(struct mei_wdt *wdt)
{
	return 0;
}
#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_event_cb(wdt->cldev,
					  BIT(MEI_CL_EVENT_RX) |
					  BIT(MEI_CL_EVENT_NOTIF),
					  mei_wdt_event, NULL);

	/* on legacy devices notification is not supported
	 * this doesn't fail the registration for RX event
	 */
	if (ret && ret != -EOPNOTSUPP) {
		dev_err(&cldev->dev, "Could not register 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;

	if (dbgfs_register(wdt))
		dev_warn(&cldev->dev, "cannot register debugfs\n");

	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 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,
};

static int __init mei_wdt_init(void)
{
	int ret;

	ret = mei_cldev_driver_register(&mei_wdt_driver);
	if (ret) {
		pr_err(KBUILD_MODNAME ": module registration failed\n");
		return ret;
	}
	return 0;
}

static void __exit mei_wdt_exit(void)
{
	mei_cldev_driver_unregister(&mei_wdt_driver);
}

module_init(mei_wdt_init);
module_exit(mei_wdt_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");
Commit	Line	Data
222818c3 TW	1	/*
	2	* Intel Management Engine Interface (Intel MEI) Linux driver
	3	* Copyright (c) 2015, Intel Corporation.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms and conditions of the GNU General Public License,
	7	* version 2, as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope it will be useful, but WITHOUT
	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	* more details.
	13	*/
	14
	15	#include <linux/module.h>
	16	#include <linux/slab.h>
	17	#include <linux/interrupt.h>
c9cf20ee	18	#include <linux/debugfs.h>
7a23f80e	19	#include <linux/completion.h>
222818c3 TW	20	#include <linux/watchdog.h>
	21
	22	#include <linux/uuid.h>
	23	#include <linux/mei_cl_bus.h>
	24
	25	/*
	26	* iAMT Watchdog Device
	27	*/
	28	#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"
	29
	30	#define MEI_WDT_DEFAULT_TIMEOUT 120 /* seconds */
	31	#define MEI_WDT_MIN_TIMEOUT 120 /* seconds */
	32	#define MEI_WDT_MAX_TIMEOUT 65535 /* seconds */
	33
	34	/* Commands */
	35	#define MEI_MANAGEMENT_CONTROL 0x02
	36
	37	/* MEI Management Control version number */
	38	#define MEI_MC_VERSION_NUMBER 0x10
	39
	40	/* Sub Commands */
	41	#define MEI_MC_START_WD_TIMER_REQ 0x13
7a23f80e TW	42	#define MEI_MC_START_WD_TIMER_RES 0x83
	43	#define MEI_WDT_STATUS_SUCCESS 0
	44	#define MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
222818c3 TW	45	#define MEI_MC_STOP_WD_TIMER_REQ 0x14
	46
	47	/**
	48	* enum mei_wdt_state - internal watchdog state
	49	*
7a23f80e	50	* @MEI_WDT_PROBE: wd in probing stage
222818c3 TW	51	* @MEI_WDT_IDLE: wd is idle and not opened
	52	* @MEI_WDT_START: wd was opened, start was called
	53	* @MEI_WDT_RUNNING: wd is expecting keep alive pings
	54	* @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
7a23f80e	55	* @MEI_WDT_NOT_REQUIRED: wd device is not required
222818c3 TW	56	*/
222818c3 TW	57	enum mei_wdt_state {
7a23f80e	58	MEI_WDT_PROBE,
222818c3 TW	59	MEI_WDT_IDLE,
	60	MEI_WDT_START,
	61	MEI_WDT_RUNNING,
	62	MEI_WDT_STOPPING,
7a23f80e	63	MEI_WDT_NOT_REQUIRED,
222818c3 TW	64	};
222818c3 TW	65
c9cf20ee TW	66	static const char *mei_wdt_state_str(enum mei_wdt_state state)
	67	{
	68	switch (state) {
7a23f80e TW	69	case MEI_WDT_PROBE:
7a23f80e TW	70	return "PROBE";
c9cf20ee TW	71	case MEI_WDT_IDLE:
	72	return "IDLE";
	73	case MEI_WDT_START:
	74	return "START";
	75	case MEI_WDT_RUNNING:
	76	return "RUNNING";
	77	case MEI_WDT_STOPPING:
	78	return "STOPPING";
7a23f80e TW	79	case MEI_WDT_NOT_REQUIRED:
7a23f80e TW	80	return "NOT_REQUIRED";
c9cf20ee TW	81	default:
	82	return "unknown";
	83	}
	84	}
c9cf20ee	85
222818c3 TW	86	/**
	87	* struct mei_wdt - mei watchdog driver
	88	* @wdd: watchdog device
	89	*
	90	* @cldev: mei watchdog client device
	91	* @state: watchdog internal state
7a23f80e TW	92	* @resp_required: ping required response
	93	* @response: ping response completion
	94	* @unregister: unregister worker
	95	* @reg_lock: watchdog device registration lock
222818c3	96	* @timeout: watchdog current timeout
c9cf20ee TW	97	*
c9cf20ee TW	98	* @dbgfs_dir: debugfs dir entry
222818c3 TW	99	*/
	100	struct mei_wdt {
	101	struct watchdog_device wdd;
	102
	103	struct mei_cl_device *cldev;
	104	enum mei_wdt_state state;
7a23f80e TW	105	bool resp_required;
	106	struct completion response;
	107	struct work_struct unregister;
	108	struct mutex reg_lock;
222818c3	109	u16 timeout;
c9cf20ee TW	110
	111	#if IS_ENABLED(CONFIG_DEBUG_FS)
	112	struct dentry *dbgfs_dir;
	113	#endif /* CONFIG_DEBUG_FS */
222818c3 TW	114	};
	115
	116	/*
	117	* struct mei_mc_hdr - Management Control Command Header
	118	*
	119	* @command: Management Control (0x2)
	120	* @bytecount: Number of bytes in the message beyond this byte
	121	* @subcommand: Management Control Subcommand
	122	* @versionnumber: Management Control Version (0x10)
	123	*/
	124	struct mei_mc_hdr {
	125	u8 command;
	126	u8 bytecount;
	127	u8 subcommand;
	128	u8 versionnumber;
	129	};
	130
	131	/**
	132	* struct mei_wdt_start_request watchdog start/ping
	133	*
	134	* @hdr: Management Control Command Header
	135	* @timeout: timeout value
	136	* @reserved: reserved (legacy)
	137	*/
	138	struct mei_wdt_start_request {
	139	struct mei_mc_hdr hdr;
	140	u16 timeout;
	141	u8 reserved[17];
	142	} __packed;
	143
7a23f80e TW	144	/**
	145	* struct mei_wdt_start_response watchdog start/ping response
	146	*
	147	* @hdr: Management Control Command Header
	148	* @status: operation status
	149	* @wdstate: watchdog status bit mask
	150	*/
	151	struct mei_wdt_start_response {
	152	struct mei_mc_hdr hdr;
	153	u8 status;
	154	u8 wdstate;
	155	} __packed;
	156
222818c3 TW	157	/**
	158	* struct mei_wdt_stop_request - watchdog stop
	159	*
	160	* @hdr: Management Control Command Header
	161	*/
	162	struct mei_wdt_stop_request {
	163	struct mei_mc_hdr hdr;
	164	} __packed;
	165
	166	/**
	167	* mei_wdt_ping - send wd start/ping command
	168	*
	169	* @wdt: mei watchdog device
	170	*
	171	* Return: 0 on success,
	172	* negative errno code on failure
	173	*/
	174	static int mei_wdt_ping(struct mei_wdt *wdt)
	175	{
	176	struct mei_wdt_start_request req;
	177	const size_t req_len = sizeof(req);
	178	int ret;
	179
	180	memset(&req, 0, req_len);
	181	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	182	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	183	req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
	184	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	185	req.timeout = wdt->timeout;
	186
	187	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	188	if (ret < 0)
	189	return ret;
	190
	191	return 0;
	192	}
	193
	194	/**
	195	* mei_wdt_stop - send wd stop command
	196	*
	197	* @wdt: mei watchdog device
	198	*
	199	* Return: 0 on success,
	200	* negative errno code on failure
	201	*/
	202	static int mei_wdt_stop(struct mei_wdt *wdt)
	203	{
	204	struct mei_wdt_stop_request req;
	205	const size_t req_len = sizeof(req);
	206	int ret;
	207
	208	memset(&req, 0, req_len);
	209	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	210	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	211	req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
	212	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	213
	214	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	215	if (ret < 0)
	216	return ret;
	217
	218	return 0;
	219	}
	220
221	/**
222	* mei_wdt_ops_start - wd start command from the watchdog core.
223	*
224	* @wdd: watchdog device
225	*
226	* Return: 0 on success or -ENODEV;
227	*/
228	static int mei_wdt_ops_start(struct watchdog_device *wdd)
229	{
230	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
231
232	wdt->state = MEI_WDT_START;
233	wdd->timeout = wdt->timeout;
234	return 0;
235	}
236
237	/**
238	* mei_wdt_ops_stop - wd stop command from the watchdog core.
239	*
240	* @wdd: watchdog device
241	*
242	* Return: 0 if success, negative errno code for failure
243	*/
244	static int mei_wdt_ops_stop(struct watchdog_device *wdd)
245	{
246	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
247	int ret;
248
249	if (wdt->state != MEI_WDT_RUNNING)
250	return 0;
251
252	wdt->state = MEI_WDT_STOPPING;
253
254	ret = mei_wdt_stop(wdt);
255	if (ret)
256	return ret;
257
258	wdt->state = MEI_WDT_IDLE;
259
260	return 0;
261	}
262
263	/**
264	* mei_wdt_ops_ping - wd ping command from the watchdog core.
265	*
266	* @wdd: watchdog device
267	*
268	* Return: 0 if success, negative errno code on failure
269	*/
270	static int mei_wdt_ops_ping(struct watchdog_device *wdd)
271	{
272	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
273	int ret;
274
275	if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
276	return 0;
277
7a23f80e TW	278	if (wdt->resp_required)
	279	init_completion(&wdt->response);
	280
	281	wdt->state = MEI_WDT_RUNNING;
222818c3 TW	282	ret = mei_wdt_ping(wdt);
	283	if (ret)
	284	return ret;
	285
7a23f80e TW	286	if (wdt->resp_required)
7a23f80e TW	287	ret = wait_for_completion_killable(&wdt->response);
222818c3	288
7a23f80e	289	return ret;
222818c3 TW	290	}
	291
	292	/**
	293	* mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
	294	*
	295	* @wdd: watchdog device
	296	* @timeout: timeout value to set
	297	*
	298	* Return: 0 if success, negative errno code for failure
	299	*/
	300	static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
	301	unsigned int timeout)
	302	{
	303
	304	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	305
	306	/* valid value is already checked by the caller */
	307	wdt->timeout = timeout;
	308	wdd->timeout = timeout;
	309
	310	return 0;
	311	}
	312
	313	static const struct watchdog_ops wd_ops = {
	314	.owner = THIS_MODULE,
	315	.start = mei_wdt_ops_start,
	316	.stop = mei_wdt_ops_stop,
	317	.ping = mei_wdt_ops_ping,
	318	.set_timeout = mei_wdt_ops_set_timeout,
	319	};
	320
	321	/* not const as the firmware_version field need to be retrieved */
	322	static struct watchdog_info wd_info = {
	323	.identity = INTEL_AMT_WATCHDOG_ID,
	324	.options = WDIOF_KEEPALIVEPING \|
	325	WDIOF_SETTIMEOUT \|
	326	WDIOF_ALARMONLY,
	327	};
	328
7a23f80e TW	329	/**
	330	* __mei_wdt_is_registered - check if wdt is registered
	331	*
	332	* @wdt: mei watchdog device
	333	*
	334	* Return: true if the wdt is registered with the watchdog subsystem
	335	* Locking: should be called under wdt->reg_lock
	336	*/
	337	static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
	338	{
	339	return !!watchdog_get_drvdata(&wdt->wdd);
	340	}
	341
222818c3 TW	342	/**
	343	* mei_wdt_unregister - unregister from the watchdog subsystem
	344	*
	345	* @wdt: mei watchdog device
	346	*/
	347	static void mei_wdt_unregister(struct mei_wdt *wdt)
	348	{
7a23f80e TW	349	mutex_lock(&wdt->reg_lock);
	350
	351	if (__mei_wdt_is_registered(wdt)) {
	352	watchdog_unregister_device(&wdt->wdd);
	353	watchdog_set_drvdata(&wdt->wdd, NULL);
	354	memset(&wdt->wdd, 0, sizeof(wdt->wdd));
	355	}
	356
	357	mutex_unlock(&wdt->reg_lock);
222818c3 TW	358	}
	359
	360	/**
	361	* mei_wdt_register - register with the watchdog subsystem
	362	*
	363	* @wdt: mei watchdog device
	364	*
	365	* Return: 0 if success, negative errno code for failure
	366	*/
	367	static int mei_wdt_register(struct mei_wdt *wdt)
	368	{
	369	struct device *dev;
	370	int ret;
	371
	372	if (!wdt \|\| !wdt->cldev)
	373	return -EINVAL;
	374
	375	dev = &wdt->cldev->dev;
	376
7a23f80e TW	377	mutex_lock(&wdt->reg_lock);
	378
	379	if (__mei_wdt_is_registered(wdt)) {
	380	ret = 0;
	381	goto out;
	382	}
	383
222818c3 TW	384	wdt->wdd.info = &wd_info;
	385	wdt->wdd.ops = &wd_ops;
	386	wdt->wdd.parent = dev;
	387	wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
	388	wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
	389	wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
	390
	391	watchdog_set_drvdata(&wdt->wdd, wdt);
	392	ret = watchdog_register_device(&wdt->wdd);
	393	if (ret) {
	394	dev_err(dev, "unable to register watchdog device = %d.\n", ret);
	395	watchdog_set_drvdata(&wdt->wdd, NULL);
	396	}
	397
7a23f80e TW	398	wdt->state = MEI_WDT_IDLE;
	399
	400	out:
	401	mutex_unlock(&wdt->reg_lock);
222818c3 TW	402	return ret;
	403	}
	404
7a23f80e TW	405	static void mei_wdt_unregister_work(struct work_struct *work)
	406	{
	407	struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
	408
	409	mei_wdt_unregister(wdt);
	410	}
	411
	412	/**
	413	* mei_wdt_event_rx - callback for data receive
	414	*
	415	* @cldev: bus device
	416	*/
	417	static void mei_wdt_event_rx(struct mei_cl_device *cldev)
	418	{
	419	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	420	struct mei_wdt_start_response res;
	421	const size_t res_len = sizeof(res);
	422	int ret;
	423
	424	ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
	425	if (ret < 0) {
	426	dev_err(&cldev->dev, "failure in recv %d\n", ret);
	427	return;
	428	}
	429
	430	/* Empty response can be sent on stop */
	431	if (ret == 0)
	432	return;
	433
	434	if (ret < sizeof(struct mei_mc_hdr)) {
	435	dev_err(&cldev->dev, "recv small data %d\n", ret);
	436	return;
	437	}
	438
	439	if (res.hdr.command != MEI_MANAGEMENT_CONTROL \|\|
	440	res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
	441	dev_err(&cldev->dev, "wrong command received\n");
	442	return;
	443	}
	444
	445	if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
	446	dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
	447	res.hdr.subcommand,
	448	mei_wdt_state_str(wdt->state),
	449	wdt->state);
	450	return;
	451	}
	452
	453	/* Run the unregistration in a worker as this can be
	454	* run only after ping completion, otherwise the flow will
	455	* deadlock on watchdog core mutex.
	456	*/
	457	if (wdt->state == MEI_WDT_RUNNING) {
	458	if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
	459	wdt->state = MEI_WDT_NOT_REQUIRED;
	460	schedule_work(&wdt->unregister);
	461	}
	462	goto out;
	463	}
	464
	465	if (wdt->state == MEI_WDT_PROBE) {
	466	if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
	467	wdt->state = MEI_WDT_NOT_REQUIRED;
	468	} else {
469	/* stop the watchdog and register watchdog device */
470	mei_wdt_stop(wdt);
471	mei_wdt_register(wdt);
472	}
473	return;
474	}
475
476	dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
477	mei_wdt_state_str(wdt->state), wdt->state);
478
479	out:
480	if (!completion_done(&wdt->response))
481	complete(&wdt->response);
482	}
483
3a20a5c3 TW	484	/*
	485	* mei_wdt_notify_event - callback for event notification
	486	*
	487	* @cldev: bus device
	488	*/
	489	static void mei_wdt_notify_event(struct mei_cl_device *cldev)
	490	{
	491	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	492
	493	if (wdt->state != MEI_WDT_NOT_REQUIRED)
	494	return;
	495
	496	mei_wdt_register(wdt);
	497	}
	498
7a23f80e TW	499	/**
	500	* mei_wdt_event - callback for event receive
	501	*
	502	* @cldev: bus device
	503	* @events: event mask
	504	* @context: callback context
	505	*/
	506	static void mei_wdt_event(struct mei_cl_device *cldev,
	507	u32 events, void *context)
	508	{
	509	if (events & BIT(MEI_CL_EVENT_RX))
	510	mei_wdt_event_rx(cldev);
3a20a5c3 TW	511
	512	if (events & BIT(MEI_CL_EVENT_NOTIF))
	513	mei_wdt_notify_event(cldev);
7a23f80e TW	514	}
7a23f80e TW	515
c9cf20ee TW	516	#if IS_ENABLED(CONFIG_DEBUG_FS)
c9cf20ee TW	517
ad1cd720 TW	518	static ssize_t mei_dbgfs_read_activation(struct file file, char __user ubuf,
	519	size_t cnt, loff_t *ppos)
	520	{
	521	struct mei_wdt *wdt = file->private_data;
	522	const size_t bufsz = 32;
	523	char buf[32];
	524	ssize_t pos;
	525
	526	mutex_lock(&wdt->reg_lock);
	527	pos = scnprintf(buf, bufsz, "%s\n",
	528	__mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
	529	mutex_unlock(&wdt->reg_lock);
	530
	531	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
	532	}
	533
	534	static const struct file_operations dbgfs_fops_activation = {
	535	.open = simple_open,
	536	.read = mei_dbgfs_read_activation,
	537	.llseek = generic_file_llseek,
	538	};
	539
c9cf20ee TW	540	static ssize_t mei_dbgfs_read_state(struct file file, char __user ubuf,
	541	size_t cnt, loff_t *ppos)
	542	{
	543	struct mei_wdt *wdt = file->private_data;
	544	const size_t bufsz = 32;
	545	char buf[bufsz];
	546	ssize_t pos;
	547
	548	pos = scnprintf(buf, bufsz, "state: %s\n",
	549	mei_wdt_state_str(wdt->state));
	550
	551	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
	552	}
	553
	554	static const struct file_operations dbgfs_fops_state = {
	555	.open = simple_open,
	556	.read = mei_dbgfs_read_state,
	557	.llseek = generic_file_llseek,
	558	};
	559
	560	static void dbgfs_unregister(struct mei_wdt *wdt)
	561	{
	562	debugfs_remove_recursive(wdt->dbgfs_dir);
	563	wdt->dbgfs_dir = NULL;
	564	}
	565
	566	static int dbgfs_register(struct mei_wdt *wdt)
	567	{
	568	struct dentry dir, f;
	569
	570	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
	571	if (!dir)
	572	return -ENOMEM;
	573
	574	wdt->dbgfs_dir = dir;
	575	f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
	576	if (!f)
	577	goto err;
	578
ad1cd720 TW	579	f = debugfs_create_file("activation", S_IRUSR,
	580	dir, wdt, &dbgfs_fops_activation);
	581	if (!f)
	582	goto err;
	583
c9cf20ee TW	584	return 0;
	585	err:
	586	dbgfs_unregister(wdt);
	587	return -ENODEV;
	588	}
	589
	590	#else
	591
	592	static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
	593
	594	static inline int dbgfs_register(struct mei_wdt *wdt)
	595	{
	596	return 0;
	597	}
	598	#endif /* CONFIG_DEBUG_FS */
	599
222818c3 TW	600	static int mei_wdt_probe(struct mei_cl_device *cldev,
	601	const struct mei_cl_device_id *id)
	602	{
	603	struct mei_wdt *wdt;
	604	int ret;
	605
	606	wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
	607	if (!wdt)
	608	return -ENOMEM;
	609
	610	wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
7a23f80e	611	wdt->state = MEI_WDT_PROBE;
222818c3	612	wdt->cldev = cldev;
7a23f80e TW	613	wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
	614	mutex_init(&wdt->reg_lock);
	615	init_completion(&wdt->response);
	616	INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
	617
222818c3 TW	618	mei_cldev_set_drvdata(cldev, wdt);
	619
	620	ret = mei_cldev_enable(cldev);
	621	if (ret < 0) {
	622	dev_err(&cldev->dev, "Could not enable cl device\n");
	623	goto err_out;
	624	}
	625
3a20a5c3 TW	626	ret = mei_cldev_register_event_cb(wdt->cldev,
	627	BIT(MEI_CL_EVENT_RX) \|
	628	BIT(MEI_CL_EVENT_NOTIF),
7a23f80e	629	mei_wdt_event, NULL);
3a20a5c3 TW	630
	631	/* on legacy devices notification is not supported
	632	* this doesn't fail the registration for RX event
	633	*/
	634	if (ret && ret != -EOPNOTSUPP) {
7a23f80e TW	635	dev_err(&cldev->dev, "Could not register event ret=%d\n", ret);
	636	goto err_disable;
	637	}
	638
222818c3 TW	639	wd_info.firmware_version = mei_cldev_ver(cldev);
222818c3 TW	640
7a23f80e TW	641	if (wdt->resp_required)
	642	ret = mei_wdt_ping(wdt);
	643	else
	644	ret = mei_wdt_register(wdt);
	645
222818c3 TW	646	if (ret)
	647	goto err_disable;
	648
c9cf20ee TW	649	if (dbgfs_register(wdt))
	650	dev_warn(&cldev->dev, "cannot register debugfs\n");
	651
222818c3 TW	652	return 0;
	653
	654	err_disable:
	655	mei_cldev_disable(cldev);
	656
	657	err_out:
	658	kfree(wdt);
	659
	660	return ret;
	661	}
	662
	663	static int mei_wdt_remove(struct mei_cl_device *cldev)
	664	{
	665	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	666
7a23f80e TW	667	/* Free the caller in case of fw initiated or unexpected reset */
	668	if (!completion_done(&wdt->response))
	669	complete(&wdt->response);
	670
	671	cancel_work_sync(&wdt->unregister);
	672
222818c3 TW	673	mei_wdt_unregister(wdt);
	674
	675	mei_cldev_disable(cldev);
	676
c9cf20ee TW	677	dbgfs_unregister(wdt);
c9cf20ee TW	678
222818c3 TW	679	kfree(wdt);
	680
	681	return 0;
	682	}
	683
	684	#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
	685	0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
	686
	687	static struct mei_cl_device_id mei_wdt_tbl[] = {
7a23f80e	688	{ .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
222818c3 TW	689	/* required last entry */
	690	{ }
	691	};
	692	MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
	693
	694	static struct mei_cl_driver mei_wdt_driver = {
	695	.id_table = mei_wdt_tbl,
	696	.name = KBUILD_MODNAME,
	697
	698	.probe = mei_wdt_probe,
	699	.remove = mei_wdt_remove,
	700	};
	701
	702	static int __init mei_wdt_init(void)
	703	{
	704	int ret;
	705
	706	ret = mei_cldev_driver_register(&mei_wdt_driver);
	707	if (ret) {
	708	pr_err(KBUILD_MODNAME ": module registration failed\n");
	709	return ret;
	710	}
	711	return 0;
	712	}
	713
	714	static void __exit mei_wdt_exit(void)
	715	{
	716	mei_cldev_driver_unregister(&mei_wdt_driver);
	717	}
	718
	719	module_init(mei_wdt_init);
	720	module_exit(mei_wdt_exit);
	721
	722	MODULE_AUTHOR("Intel Corporation");
	723	MODULE_LICENSE("GPL");
	724	MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");