/* * 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); 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; 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_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"); MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");