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