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
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_NOWAYOUT
43module_param(nowayout, bool, 0);
44MODULE_PARM_DESC(nowayout,
45		"Watchdog cannot be stopped once started (default="
46				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
47#endif
48
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 also
118 *  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 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
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	.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
221static struct miscdevice at91wdt_miscdev = {
222	.minor		= WATCHDOG_MINOR,
223	.name		= "watchdog",
224	.fops		= &at91wdt_fops,
225};
226
227static 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
260static 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
273static void at91wdt_shutdown(struct platform_device *pdev)
274{
275	at91_wdt_stop();
276}
277
278static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
279{
280	at91_wdt_stop();
281	return 0;
282}
283
284static int at91wdt_resume(struct platform_device *pdev)
285{
286	if (at91wdt_busy)
287		at91_wdt_start();
288	return 0;
289}
290
291static const struct of_device_id at91_wdt_dt_ids[] = {
292	{ .compatible = "atmel,at91rm9200-wdt" },
293	{ /* sentinel */ }
294};
295MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
296
297static 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
309static 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
322static void __exit at91_wdt_exit(void)
323{
324	platform_driver_unregister(&at91wdt_driver);
325}
326
327module_init(at91_wdt_init);
328module_exit(at91_wdt_exit);
329
330MODULE_AUTHOR("Andrew Victor");
331MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
332MODULE_LICENSE("GPL");
333MODULE_ALIAS("platform:atmel_st_watchdog");
334