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/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
34 static int wdt_time = WDT_DEFAULT_TIME;
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36 static struct regmap *regmap_st;
37
38 module_param(wdt_time, int, 0);
39 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
40 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
41
42 #ifdef CONFIG_WATCHDOG_NOWAYOUT
43 module_param(nowayout, bool, 0);
44 MODULE_PARM_DESC(nowayout,
45 "Watchdog cannot be stopped once started (default="
46 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
47 #endif
48
49
50 static unsigned long at91wdt_busy;
51
52 /* ......................................................................... */
53
at91rm9200_restart(struct notifier_block * this,unsigned long mode,void * cmd)54 static 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
70 static struct notifier_block at91rm9200_restart_nb = {
71 .notifier_call = at91rm9200_restart,
72 .priority = 192,
73 };
74
75 /*
76 * Disable the watchdog.
77 */
at91_wdt_stop(void)78 static 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 */
at91_wdt_start(void)86 static 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 */
at91_wdt_reload(void)96 static 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 */
at91_wdt_open(struct inode * inode,struct file * file)106 static 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 also
118 * disabled.
119 */
at91_wdt_close(struct inode * inode,struct file * file)120 static 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 */
at91_wdt_settimeout(int new_time)133 static int at91_wdt_settimeout(int new_time)
134 {
135 /*
136 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
137 *
138 * Since WDV is a 16-bit counter, the maximum period is
139 * 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 when
145 at91_wdt_start() is called. */
146 wdt_time = new_time;
147 return 0;
148 }
149
150 static 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 */
at91_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)158 static 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 */
at91_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)202 static 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
211 static const struct file_operations at91wdt_fops = {
212 .owner = THIS_MODULE,
213 .llseek = no_llseek,
214 .unlocked_ioctl = at91_wdt_ioctl,
215 .compat_ioctl = compat_ptr_ioctl,
216 .open = at91_wdt_open,
217 .release = at91_wdt_close,
218 .write = at91_wdt_write,
219 };
220
221 static struct miscdevice at91wdt_miscdev = {
222 .minor = WATCHDOG_MINOR,
223 .name = "watchdog",
224 .fops = &at91wdt_fops,
225 };
226
at91wdt_probe(struct platform_device * pdev)227 static int at91wdt_probe(struct platform_device *pdev)
228 {
229 struct device *dev = &pdev->dev;
230 struct device *parent;
231 int res;
232
233 if (at91wdt_miscdev.parent)
234 return -EBUSY;
235 at91wdt_miscdev.parent = &pdev->dev;
236
237 parent = dev->parent;
238 if (!parent) {
239 dev_err(dev, "no parent\n");
240 return -ENODEV;
241 }
242
243 regmap_st = syscon_node_to_regmap(parent->of_node);
244 if (IS_ERR(regmap_st))
245 return -ENODEV;
246
247 res = misc_register(&at91wdt_miscdev);
248 if (res)
249 return res;
250
251 res = register_restart_handler(&at91rm9200_restart_nb);
252 if (res)
253 dev_warn(dev, "failed to register restart handler\n");
254
255 pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
256 wdt_time, nowayout ? ", nowayout" : "");
257 return 0;
258 }
259
at91wdt_remove(struct platform_device * pdev)260 static void at91wdt_remove(struct platform_device *pdev)
261 {
262 struct device *dev = &pdev->dev;
263 int res;
264
265 res = unregister_restart_handler(&at91rm9200_restart_nb);
266 if (res)
267 dev_warn(dev, "failed to unregister restart handler\n");
268
269 misc_deregister(&at91wdt_miscdev);
270 at91wdt_miscdev.parent = NULL;
271 }
272
at91wdt_shutdown(struct platform_device * pdev)273 static void at91wdt_shutdown(struct platform_device *pdev)
274 {
275 at91_wdt_stop();
276 }
277
at91wdt_suspend(struct platform_device * pdev,pm_message_t message)278 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
279 {
280 at91_wdt_stop();
281 return 0;
282 }
283
at91wdt_resume(struct platform_device * pdev)284 static int at91wdt_resume(struct platform_device *pdev)
285 {
286 if (at91wdt_busy)
287 at91_wdt_start();
288 return 0;
289 }
290
291 static const struct of_device_id at91_wdt_dt_ids[] = {
292 { .compatible = "atmel,at91rm9200-wdt" },
293 { /* sentinel */ }
294 };
295 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
296
297 static struct platform_driver at91wdt_driver = {
298 .probe = at91wdt_probe,
299 .remove_new = at91wdt_remove,
300 .shutdown = at91wdt_shutdown,
301 .suspend = pm_ptr(at91wdt_suspend),
302 .resume = pm_ptr(at91wdt_resume),
303 .driver = {
304 .name = "atmel_st_watchdog",
305 .of_match_table = at91_wdt_dt_ids,
306 },
307 };
308
at91_wdt_init(void)309 static int __init at91_wdt_init(void)
310 {
311 /* Check that the heartbeat value is within range;
312 if not reset to the default */
313 if (at91_wdt_settimeout(wdt_time)) {
314 at91_wdt_settimeout(WDT_DEFAULT_TIME);
315 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
316 wdt_time);
317 }
318
319 return platform_driver_register(&at91wdt_driver);
320 }
321
at91_wdt_exit(void)322 static void __exit at91_wdt_exit(void)
323 {
324 platform_driver_unregister(&at91wdt_driver);
325 }
326
327 module_init(at91_wdt_init);
328 module_exit(at91_wdt_exit);
329
330 MODULE_AUTHOR("Andrew Victor");
331 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
332 MODULE_LICENSE("GPL");
333 MODULE_ALIAS("platform:atmel_st_watchdog");
334