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/*
* 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
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