1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Watchdog driver for Atmel AT91RM9200 (Thunder)
4 *
5 * Copyright (C) 2003 SAN People (Pty) Ltd
6 *
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
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/module.h>
22 #include <linux/moduleparam.h>
23 #include <linux/platform_device.h>
24 #include <linux/reboot.h>
25 #include <linux/regmap.h>
26 #include <linux/types.h>
27 #include <linux/watchdog.h>
28 #include <linux/uaccess.h>
29 #include <linux/of.h>
30 #include <linux/of_device.h>
31
32 #define WDT_DEFAULT_TIME 5 /* seconds */
33 #define WDT_MAX_TIME 256 /* seconds */
34
35 static int wdt_time = WDT_DEFAULT_TIME;
36 static bool nowayout = WATCHDOG_NOWAYOUT;
37 static struct regmap *regmap_st;
38
39 module_param(wdt_time, int, 0);
40 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
41 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
42
43 #ifdef CONFIG_WATCHDOG_NOWAYOUT
44 module_param(nowayout, bool, 0);
45 MODULE_PARM_DESC(nowayout,
46 "Watchdog cannot be stopped once started (default="
47 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
48 #endif
49
50
51 static unsigned long at91wdt_busy;
52
53 /* ......................................................................... */
54
at91rm9200_restart(struct notifier_block * this,unsigned long mode,void * cmd)55 static int at91rm9200_restart(struct notifier_block *this,
56 unsigned long mode, void *cmd)
57 {
58 /*
59 * Perform a hardware reset with the use of the Watchdog timer.
60 */
61 regmap_write(regmap_st, AT91_ST_WDMR,
62 AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
63 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
64
65 mdelay(2000);
66
67 pr_emerg("Unable to restart system\n");
68 return NOTIFY_DONE;
69 }
70
71 static struct notifier_block at91rm9200_restart_nb = {
72 .notifier_call = at91rm9200_restart,
73 .priority = 192,
74 };
75
76 /*
77 * Disable the watchdog.
78 */
at91_wdt_stop(void)79 static inline void at91_wdt_stop(void)
80 {
81 regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN);
82 }
83
84 /*
85 * Enable and reset the watchdog.
86 */
at91_wdt_start(void)87 static inline void at91_wdt_start(void)
88 {
89 regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
90 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
91 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
92 }
93
94 /*
95 * Reload the watchdog timer. (ie, pat the watchdog)
96 */
at91_wdt_reload(void)97 static inline void at91_wdt_reload(void)
98 {
99 regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
100 }
101
102 /* ......................................................................... */
103
104 /*
105 * Watchdog device is opened, and watchdog starts running.
106 */
at91_wdt_open(struct inode * inode,struct file * file)107 static int at91_wdt_open(struct inode *inode, struct file *file)
108 {
109 if (test_and_set_bit(0, &at91wdt_busy))
110 return -EBUSY;
111
112 at91_wdt_start();
113 return stream_open(inode, file);
114 }
115
116 /*
117 * Close the watchdog device.
118 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
119 * disabled.
120 */
at91_wdt_close(struct inode * inode,struct file * file)121 static int at91_wdt_close(struct inode *inode, struct file *file)
122 {
123 /* Disable the watchdog when file is closed */
124 if (!nowayout)
125 at91_wdt_stop();
126
127 clear_bit(0, &at91wdt_busy);
128 return 0;
129 }
130
131 /*
132 * Change the watchdog time interval.
133 */
at91_wdt_settimeout(int new_time)134 static int at91_wdt_settimeout(int new_time)
135 {
136 /*
137 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
138 *
139 * Since WDV is a 16-bit counter, the maximum period is
140 * 65536 / 256 = 256 seconds.
141 */
142 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
143 return -EINVAL;
144
145 /* Set new watchdog time. It will be used when
146 at91_wdt_start() is called. */
147 wdt_time = new_time;
148 return 0;
149 }
150
151 static const struct watchdog_info at91_wdt_info = {
152 .identity = "at91 watchdog",
153 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
154 };
155
156 /*
157 * Handle commands from user-space.
158 */
at91_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)159 static long at91_wdt_ioctl(struct file *file,
160 unsigned int cmd, unsigned long arg)
161 {
162 void __user *argp = (void __user *)arg;
163 int __user *p = argp;
164 int new_value;
165
166 switch (cmd) {
167 case WDIOC_GETSUPPORT:
168 return copy_to_user(argp, &at91_wdt_info,
169 sizeof(at91_wdt_info)) ? -EFAULT : 0;
170 case WDIOC_GETSTATUS:
171 case WDIOC_GETBOOTSTATUS:
172 return put_user(0, p);
173 case WDIOC_SETOPTIONS:
174 if (get_user(new_value, p))
175 return -EFAULT;
176 if (new_value & WDIOS_DISABLECARD)
177 at91_wdt_stop();
178 if (new_value & WDIOS_ENABLECARD)
179 at91_wdt_start();
180 return 0;
181 case WDIOC_KEEPALIVE:
182 at91_wdt_reload(); /* pat the watchdog */
183 return 0;
184 case WDIOC_SETTIMEOUT:
185 if (get_user(new_value, p))
186 return -EFAULT;
187 if (at91_wdt_settimeout(new_value))
188 return -EINVAL;
189 /* Enable new time value */
190 at91_wdt_start();
191 /* Return current value */
192 return put_user(wdt_time, p);
193 case WDIOC_GETTIMEOUT:
194 return put_user(wdt_time, p);
195 default:
196 return -ENOTTY;
197 }
198 }
199
200 /*
201 * Pat the watchdog whenever device is written to.
202 */
at91_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)203 static ssize_t at91_wdt_write(struct file *file, const char *data,
204 size_t len, loff_t *ppos)
205 {
206 at91_wdt_reload(); /* pat the watchdog */
207 return len;
208 }
209
210 /* ......................................................................... */
211
212 static const struct file_operations at91wdt_fops = {
213 .owner = THIS_MODULE,
214 .llseek = no_llseek,
215 .unlocked_ioctl = at91_wdt_ioctl,
216 .compat_ioctl = compat_ptr_ioctl,
217 .open = at91_wdt_open,
218 .release = at91_wdt_close,
219 .write = at91_wdt_write,
220 };
221
222 static struct miscdevice at91wdt_miscdev = {
223 .minor = WATCHDOG_MINOR,
224 .name = "watchdog",
225 .fops = &at91wdt_fops,
226 };
227
at91wdt_probe(struct platform_device * pdev)228 static int at91wdt_probe(struct platform_device *pdev)
229 {
230 struct device *dev = &pdev->dev;
231 struct device *parent;
232 int res;
233
234 if (at91wdt_miscdev.parent)
235 return -EBUSY;
236 at91wdt_miscdev.parent = &pdev->dev;
237
238 parent = dev->parent;
239 if (!parent) {
240 dev_err(dev, "no parent\n");
241 return -ENODEV;
242 }
243
244 regmap_st = syscon_node_to_regmap(parent->of_node);
245 if (IS_ERR(regmap_st))
246 return -ENODEV;
247
248 res = misc_register(&at91wdt_miscdev);
249 if (res)
250 return res;
251
252 res = register_restart_handler(&at91rm9200_restart_nb);
253 if (res)
254 dev_warn(dev, "failed to register restart handler\n");
255
256 pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
257 wdt_time, nowayout ? ", nowayout" : "");
258 return 0;
259 }
260
at91wdt_remove(struct platform_device * pdev)261 static int at91wdt_remove(struct platform_device *pdev)
262 {
263 struct device *dev = &pdev->dev;
264 int res;
265
266 res = unregister_restart_handler(&at91rm9200_restart_nb);
267 if (res)
268 dev_warn(dev, "failed to unregister restart handler\n");
269
270 misc_deregister(&at91wdt_miscdev);
271 at91wdt_miscdev.parent = NULL;
272
273 return res;
274 }
275
at91wdt_shutdown(struct platform_device * pdev)276 static void at91wdt_shutdown(struct platform_device *pdev)
277 {
278 at91_wdt_stop();
279 }
280
281 #ifdef CONFIG_PM
282
at91wdt_suspend(struct platform_device * pdev,pm_message_t message)283 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
284 {
285 at91_wdt_stop();
286 return 0;
287 }
288
at91wdt_resume(struct platform_device * pdev)289 static int at91wdt_resume(struct platform_device *pdev)
290 {
291 if (at91wdt_busy)
292 at91_wdt_start();
293 return 0;
294 }
295
296 #else
297 #define at91wdt_suspend NULL
298 #define at91wdt_resume NULL
299 #endif
300
301 static const struct of_device_id at91_wdt_dt_ids[] = {
302 { .compatible = "atmel,at91rm9200-wdt" },
303 { /* sentinel */ }
304 };
305 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
306
307 static struct platform_driver at91wdt_driver = {
308 .probe = at91wdt_probe,
309 .remove = at91wdt_remove,
310 .shutdown = at91wdt_shutdown,
311 .suspend = at91wdt_suspend,
312 .resume = at91wdt_resume,
313 .driver = {
314 .name = "atmel_st_watchdog",
315 .of_match_table = at91_wdt_dt_ids,
316 },
317 };
318
at91_wdt_init(void)319 static int __init at91_wdt_init(void)
320 {
321 /* Check that the heartbeat value is within range;
322 if not reset to the default */
323 if (at91_wdt_settimeout(wdt_time)) {
324 at91_wdt_settimeout(WDT_DEFAULT_TIME);
325 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
326 wdt_time);
327 }
328
329 return platform_driver_register(&at91wdt_driver);
330 }
331
at91_wdt_exit(void)332 static void __exit at91_wdt_exit(void)
333 {
334 platform_driver_unregister(&at91wdt_driver);
335 }
336
337 module_init(at91_wdt_init);
338 module_exit(at91_wdt_exit);
339
340 MODULE_AUTHOR("Andrew Victor");
341 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
342 MODULE_LICENSE("GPL");
343 MODULE_ALIAS("platform:atmel_st_watchdog");
344