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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Watchdog driver for Atmel AT91RM9200 (Thunder)4 *5 * Copyright (C) 2003 SAN People (Pty) Ltd6 *7 */8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt10 11#include <linux/bitops.h>12#include <linux/delay.h>13#include <linux/errno.h>14#include <linux/fs.h>15#include <linux/init.h>16#include <linux/io.h>17#include <linux/kernel.h>18#include <linux/mfd/syscon.h>19#include <linux/mfd/syscon/atmel-st.h>20#include <linux/miscdevice.h>21#include <linux/mod_devicetable.h>22#include <linux/module.h>23#include <linux/moduleparam.h>24#include <linux/platform_device.h>25#include <linux/reboot.h>26#include <linux/regmap.h>27#include <linux/types.h>28#include <linux/watchdog.h>29#include <linux/uaccess.h>30 31#define WDT_DEFAULT_TIME 5 /* seconds */32#define WDT_MAX_TIME 256 /* seconds */33 34static int wdt_time = WDT_DEFAULT_TIME;35static bool nowayout = WATCHDOG_NOWAYOUT;36static struct regmap *regmap_st;37 38module_param(wdt_time, int, 0);39MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="40 __MODULE_STRING(WDT_DEFAULT_TIME) ")");41 42#ifdef CONFIG_WATCHDOG_NOWAYOUT43module_param(nowayout, bool, 0);44MODULE_PARM_DESC(nowayout,45 "Watchdog cannot be stopped once started (default="46 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");47#endif48 49 50static unsigned long at91wdt_busy;51 52/* ......................................................................... */53 54static int at91rm9200_restart(struct notifier_block *this,55 unsigned long mode, void *cmd)56{57 /*58 * Perform a hardware reset with the use of the Watchdog timer.59 */60 regmap_write(regmap_st, AT91_ST_WDMR,61 AT91_ST_RSTEN | AT91_ST_EXTEN | 1);62 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);63 64 mdelay(2000);65 66 pr_emerg("Unable to restart system\n");67 return NOTIFY_DONE;68}69 70static struct notifier_block at91rm9200_restart_nb = {71 .notifier_call = at91rm9200_restart,72 .priority = 192,73};74 75/*76 * Disable the watchdog.77 */78static inline void at91_wdt_stop(void)79{80 regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN);81}82 83/*84 * Enable and reset the watchdog.85 */86static inline void at91_wdt_start(void)87{88 regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |89 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));90 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);91}92 93/*94 * Reload the watchdog timer. (ie, pat the watchdog)95 */96static inline void at91_wdt_reload(void)97{98 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);99}100 101/* ......................................................................... */102 103/*104 * Watchdog device is opened, and watchdog starts running.105 */106static int at91_wdt_open(struct inode *inode, struct file *file)107{108 if (test_and_set_bit(0, &at91wdt_busy))109 return -EBUSY;110 111 at91_wdt_start();112 return stream_open(inode, file);113}114 115/*116 * Close the watchdog device.117 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also118 * disabled.119 */120static int at91_wdt_close(struct inode *inode, struct file *file)121{122 /* Disable the watchdog when file is closed */123 if (!nowayout)124 at91_wdt_stop();125 126 clear_bit(0, &at91wdt_busy);127 return 0;128}129 130/*131 * Change the watchdog time interval.132 */133static int at91_wdt_settimeout(int new_time)134{135 /*136 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz137 *138 * Since WDV is a 16-bit counter, the maximum period is139 * 65536 / 256 = 256 seconds.140 */141 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))142 return -EINVAL;143 144 /* Set new watchdog time. It will be used when145 at91_wdt_start() is called. */146 wdt_time = new_time;147 return 0;148}149 150static const struct watchdog_info at91_wdt_info = {151 .identity = "at91 watchdog",152 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,153};154 155/*156 * Handle commands from user-space.157 */158static long at91_wdt_ioctl(struct file *file,159 unsigned int cmd, unsigned long arg)160{161 void __user *argp = (void __user *)arg;162 int __user *p = argp;163 int new_value;164 165 switch (cmd) {166 case WDIOC_GETSUPPORT:167 return copy_to_user(argp, &at91_wdt_info,168 sizeof(at91_wdt_info)) ? -EFAULT : 0;169 case WDIOC_GETSTATUS:170 case WDIOC_GETBOOTSTATUS:171 return put_user(0, p);172 case WDIOC_SETOPTIONS:173 if (get_user(new_value, p))174 return -EFAULT;175 if (new_value & WDIOS_DISABLECARD)176 at91_wdt_stop();177 if (new_value & WDIOS_ENABLECARD)178 at91_wdt_start();179 return 0;180 case WDIOC_KEEPALIVE:181 at91_wdt_reload(); /* pat the watchdog */182 return 0;183 case WDIOC_SETTIMEOUT:184 if (get_user(new_value, p))185 return -EFAULT;186 if (at91_wdt_settimeout(new_value))187 return -EINVAL;188 /* Enable new time value */189 at91_wdt_start();190 /* Return current value */191 return put_user(wdt_time, p);192 case WDIOC_GETTIMEOUT:193 return put_user(wdt_time, p);194 default:195 return -ENOTTY;196 }197}198 199/*200 * Pat the watchdog whenever device is written to.201 */202static ssize_t at91_wdt_write(struct file *file, const char *data,203 size_t len, loff_t *ppos)204{205 at91_wdt_reload(); /* pat the watchdog */206 return len;207}208 209/* ......................................................................... */210 211static const struct file_operations at91wdt_fops = {212 .owner = THIS_MODULE,213 .unlocked_ioctl = at91_wdt_ioctl,214 .compat_ioctl = compat_ptr_ioctl,215 .open = at91_wdt_open,216 .release = at91_wdt_close,217 .write = at91_wdt_write,218};219 220static struct miscdevice at91wdt_miscdev = {221 .minor = WATCHDOG_MINOR,222 .name = "watchdog",223 .fops = &at91wdt_fops,224};225 226static int at91wdt_probe(struct platform_device *pdev)227{228 struct device *dev = &pdev->dev;229 struct device *parent;230 int res;231 232 if (at91wdt_miscdev.parent)233 return -EBUSY;234 at91wdt_miscdev.parent = &pdev->dev;235 236 parent = dev->parent;237 if (!parent) {238 dev_err(dev, "no parent\n");239 return -ENODEV;240 }241 242 regmap_st = syscon_node_to_regmap(parent->of_node);243 if (IS_ERR(regmap_st))244 return -ENODEV;245 246 res = misc_register(&at91wdt_miscdev);247 if (res)248 return res;249 250 res = register_restart_handler(&at91rm9200_restart_nb);251 if (res)252 dev_warn(dev, "failed to register restart handler\n");253 254 pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",255 wdt_time, nowayout ? ", nowayout" : "");256 return 0;257}258 259static void at91wdt_remove(struct platform_device *pdev)260{261 struct device *dev = &pdev->dev;262 int res;263 264 res = unregister_restart_handler(&at91rm9200_restart_nb);265 if (res)266 dev_warn(dev, "failed to unregister restart handler\n");267 268 misc_deregister(&at91wdt_miscdev);269 at91wdt_miscdev.parent = NULL;270}271 272static void at91wdt_shutdown(struct platform_device *pdev)273{274 at91_wdt_stop();275}276 277static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)278{279 at91_wdt_stop();280 return 0;281}282 283static int at91wdt_resume(struct platform_device *pdev)284{285 if (at91wdt_busy)286 at91_wdt_start();287 return 0;288}289 290static const struct of_device_id at91_wdt_dt_ids[] = {291 { .compatible = "atmel,at91rm9200-wdt" },292 { /* sentinel */ }293};294MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);295 296static struct platform_driver at91wdt_driver = {297 .probe = at91wdt_probe,298 .remove_new = at91wdt_remove,299 .shutdown = at91wdt_shutdown,300 .suspend = pm_ptr(at91wdt_suspend),301 .resume = pm_ptr(at91wdt_resume),302 .driver = {303 .name = "atmel_st_watchdog",304 .of_match_table = at91_wdt_dt_ids,305 },306};307 308static int __init at91_wdt_init(void)309{310 /* Check that the heartbeat value is within range;311 if not reset to the default */312 if (at91_wdt_settimeout(wdt_time)) {313 at91_wdt_settimeout(WDT_DEFAULT_TIME);314 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",315 wdt_time);316 }317 318 return platform_driver_register(&at91wdt_driver);319}320 321static void __exit at91_wdt_exit(void)322{323 platform_driver_unregister(&at91wdt_driver);324}325 326module_init(at91_wdt_init);327module_exit(at91_wdt_exit);328 329MODULE_AUTHOR("Andrew Victor");330MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");331MODULE_LICENSE("GPL");332MODULE_ALIAS("platform:atmel_st_watchdog");333