diff options
Diffstat (limited to 'drivers/watchdog/mei_wdt.c')
| -rw-r--r-- | drivers/watchdog/mei_wdt.c | 664 |
1 files changed, 664 insertions, 0 deletions
diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c new file mode 100644 index 000000000..c7a7235e6 --- /dev/null +++ b/drivers/watchdog/mei_wdt.c @@ -0,0 +1,664 @@ +// 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); + watchdog_stop_on_unregister(&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 void 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); +} + +#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"); |