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(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 | |
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(map: 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(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 | */ |
96 | static 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 | */ |
106 | static 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 | */ |
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(nr: 0, addr: &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(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 | */ |
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(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 | |
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(misc: &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(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 | |
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 | |