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 
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  */
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  */
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  */
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  */
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  */
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  */
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  */
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  */
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 
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 
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 
273 static void at91wdt_shutdown(struct platform_device *pdev)
274 {
275 	at91_wdt_stop();
276 }
277 
278 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
279 {
280 	at91_wdt_stop();
281 	return 0;
282 }
283 
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 
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 
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