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(map: regmap_st, AT91_ST_WDMR,
61 AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
62 regmap_write(map: 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(map: 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(map: regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
89 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
90 regmap_write(map: 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(map: 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(nr: 0, addr: &at91wdt_busy))
109 return -EBUSY;
110
111 at91_wdt_start();
112 return stream_open(inode, filp: 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(nr: 0, addr: &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(to: argp, from: &at91_wdt_info,
168 n: 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_time: 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(np: parent->of_node);
244 if (IS_ERR(ptr: regmap_st))
245 return -ENODEV;
246
247 res = misc_register(misc: &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(misc: &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(new_time: 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

source code of linux/drivers/watchdog/at91rm9200_wdt.c