linux/drivers/watchdog/mei_wdt.c

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// 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) {
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_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 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_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;
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 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");