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66aaa7a5 MZ |
1 | /* |
2 | * drivers/char/watchdog/max63xx_wdt.c | |
3 | * | |
4 | * Driver for max63{69,70,71,72,73,74} watchdog timers | |
5 | * | |
6 | * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org> | |
7 | * | |
8 | * This file is licensed under the terms of the GNU General Public | |
9 | * License version 2. This program is licensed "as is" without any | |
10 | * warranty of any kind, whether express or implied. | |
11 | * | |
12 | * This driver assumes the watchdog pins are memory mapped (as it is | |
13 | * the case for the Arcom Zeus). Should it be connected over GPIOs or | |
14 | * another interface, some abstraction will have to be introduced. | |
15 | */ | |
16 | ||
17 | #include <linux/module.h> | |
18 | #include <linux/moduleparam.h> | |
19 | #include <linux/types.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/miscdevice.h> | |
23 | #include <linux/watchdog.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/bitops.h> | |
26 | #include <linux/platform_device.h> | |
27 | #include <linux/spinlock.h> | |
28 | #include <linux/uaccess.h> | |
29 | #include <linux/io.h> | |
30 | #include <linux/device.h> | |
5a0e3ad6 | 31 | #include <linux/slab.h> |
66aaa7a5 MZ |
32 | |
33 | #define DEFAULT_HEARTBEAT 60 | |
34 | #define MAX_HEARTBEAT 60 | |
35 | ||
36 | static int heartbeat = DEFAULT_HEARTBEAT; | |
37 | static int nowayout = WATCHDOG_NOWAYOUT; | |
38 | ||
39 | /* | |
40 | * Memory mapping: a single byte, 3 first lower bits to select bit 3 | |
41 | * to ping the watchdog. | |
42 | */ | |
43 | #define MAX6369_WDSET (7 << 0) | |
44 | #define MAX6369_WDI (1 << 3) | |
45 | ||
46 | static DEFINE_SPINLOCK(io_lock); | |
47 | ||
48 | static unsigned long wdt_status; | |
49 | #define WDT_IN_USE 0 | |
50 | #define WDT_RUNNING 1 | |
51 | #define WDT_OK_TO_CLOSE 2 | |
52 | ||
53 | static int nodelay; | |
54 | static struct resource *wdt_mem; | |
55 | static void __iomem *wdt_base; | |
56 | static struct platform_device *max63xx_pdev; | |
57 | ||
58 | /* | |
59 | * The timeout values used are actually the absolute minimum the chip | |
60 | * offers. Typical values on my board are slightly over twice as long | |
61 | * (10s setting ends up with a 25s timeout), and can be up to 3 times | |
62 | * the nominal setting (according to the datasheet). So please take | |
63 | * these values with a grain of salt. Same goes for the initial delay | |
64 | * "feature". Only max6373/74 have a few settings without this initial | |
65 | * delay (selected with the "nodelay" parameter). | |
66 | * | |
67 | * I also decided to remove from the tables any timeout smaller than a | |
68 | * second, as it looked completly overkill... | |
69 | */ | |
70 | ||
71 | /* Timeouts in second */ | |
72 | struct max63xx_timeout { | |
73 | u8 wdset; | |
74 | u8 tdelay; | |
75 | u8 twd; | |
76 | }; | |
77 | ||
78 | static struct max63xx_timeout max6369_table[] = { | |
79 | { 5, 1, 1 }, | |
80 | { 6, 10, 10 }, | |
81 | { 7, 60, 60 }, | |
82 | { }, | |
83 | }; | |
84 | ||
85 | static struct max63xx_timeout max6371_table[] = { | |
86 | { 6, 60, 3 }, | |
87 | { 7, 60, 60 }, | |
88 | { }, | |
89 | }; | |
90 | ||
91 | static struct max63xx_timeout max6373_table[] = { | |
92 | { 2, 60, 1 }, | |
93 | { 5, 0, 1 }, | |
94 | { 1, 3, 3 }, | |
95 | { 7, 60, 10 }, | |
96 | { 6, 0, 10 }, | |
97 | { }, | |
98 | }; | |
99 | ||
100 | static struct max63xx_timeout *current_timeout; | |
101 | ||
102 | static struct max63xx_timeout * | |
103 | max63xx_select_timeout(struct max63xx_timeout *table, int value) | |
104 | { | |
105 | while (table->twd) { | |
106 | if (value <= table->twd) { | |
107 | if (nodelay && table->tdelay == 0) | |
108 | return table; | |
109 | ||
110 | if (!nodelay) | |
111 | return table; | |
112 | } | |
113 | ||
114 | table++; | |
115 | } | |
116 | ||
117 | return NULL; | |
118 | } | |
119 | ||
120 | static void max63xx_wdt_ping(void) | |
121 | { | |
122 | u8 val; | |
123 | ||
124 | spin_lock(&io_lock); | |
125 | ||
126 | val = __raw_readb(wdt_base); | |
127 | ||
128 | __raw_writeb(val | MAX6369_WDI, wdt_base); | |
129 | __raw_writeb(val & ~MAX6369_WDI, wdt_base); | |
130 | ||
131 | spin_unlock(&io_lock); | |
132 | } | |
133 | ||
134 | static void max63xx_wdt_enable(struct max63xx_timeout *entry) | |
135 | { | |
136 | u8 val; | |
137 | ||
138 | if (test_and_set_bit(WDT_RUNNING, &wdt_status)) | |
139 | return; | |
140 | ||
141 | spin_lock(&io_lock); | |
142 | ||
143 | val = __raw_readb(wdt_base); | |
144 | val &= ~MAX6369_WDSET; | |
145 | val |= entry->wdset; | |
146 | __raw_writeb(val, wdt_base); | |
147 | ||
148 | spin_unlock(&io_lock); | |
149 | ||
150 | /* check for a edge triggered startup */ | |
151 | if (entry->tdelay == 0) | |
152 | max63xx_wdt_ping(); | |
153 | } | |
154 | ||
155 | static void max63xx_wdt_disable(void) | |
156 | { | |
b1183e06 MZ |
157 | u8 val; |
158 | ||
66aaa7a5 MZ |
159 | spin_lock(&io_lock); |
160 | ||
b1183e06 MZ |
161 | val = __raw_readb(wdt_base); |
162 | val &= ~MAX6369_WDSET; | |
163 | val |= 3; | |
164 | __raw_writeb(val, wdt_base); | |
66aaa7a5 MZ |
165 | |
166 | spin_unlock(&io_lock); | |
167 | ||
168 | clear_bit(WDT_RUNNING, &wdt_status); | |
169 | } | |
170 | ||
171 | static int max63xx_wdt_open(struct inode *inode, struct file *file) | |
172 | { | |
173 | if (test_and_set_bit(WDT_IN_USE, &wdt_status)) | |
174 | return -EBUSY; | |
175 | ||
176 | max63xx_wdt_enable(current_timeout); | |
177 | clear_bit(WDT_OK_TO_CLOSE, &wdt_status); | |
178 | ||
179 | return nonseekable_open(inode, file); | |
180 | } | |
181 | ||
182 | static ssize_t max63xx_wdt_write(struct file *file, const char *data, | |
183 | size_t len, loff_t *ppos) | |
184 | { | |
185 | if (len) { | |
186 | if (!nowayout) { | |
187 | size_t i; | |
188 | ||
189 | clear_bit(WDT_OK_TO_CLOSE, &wdt_status); | |
190 | for (i = 0; i != len; i++) { | |
191 | char c; | |
192 | ||
193 | if (get_user(c, data + i)) | |
194 | return -EFAULT; | |
195 | ||
196 | if (c == 'V') | |
197 | set_bit(WDT_OK_TO_CLOSE, &wdt_status); | |
198 | } | |
199 | } | |
200 | ||
201 | max63xx_wdt_ping(); | |
202 | } | |
203 | ||
204 | return len; | |
205 | } | |
206 | ||
207 | static const struct watchdog_info ident = { | |
208 | .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, | |
209 | .identity = "max63xx Watchdog", | |
210 | }; | |
211 | ||
212 | static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd, | |
213 | unsigned long arg) | |
214 | { | |
215 | int ret = -ENOTTY; | |
216 | ||
217 | switch (cmd) { | |
218 | case WDIOC_GETSUPPORT: | |
219 | ret = copy_to_user((struct watchdog_info *)arg, &ident, | |
220 | sizeof(ident)) ? -EFAULT : 0; | |
221 | break; | |
222 | ||
223 | case WDIOC_GETSTATUS: | |
224 | case WDIOC_GETBOOTSTATUS: | |
225 | ret = put_user(0, (int *)arg); | |
226 | break; | |
227 | ||
228 | case WDIOC_KEEPALIVE: | |
229 | max63xx_wdt_ping(); | |
230 | ret = 0; | |
231 | break; | |
232 | ||
233 | case WDIOC_GETTIMEOUT: | |
234 | ret = put_user(heartbeat, (int *)arg); | |
235 | break; | |
236 | } | |
237 | return ret; | |
238 | } | |
239 | ||
240 | static int max63xx_wdt_release(struct inode *inode, struct file *file) | |
241 | { | |
242 | if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) | |
243 | max63xx_wdt_disable(); | |
244 | else | |
245 | dev_crit(&max63xx_pdev->dev, | |
246 | "device closed unexpectedly - timer will not stop\n"); | |
247 | ||
248 | clear_bit(WDT_IN_USE, &wdt_status); | |
249 | clear_bit(WDT_OK_TO_CLOSE, &wdt_status); | |
250 | ||
251 | return 0; | |
252 | } | |
253 | ||
254 | static const struct file_operations max63xx_wdt_fops = { | |
255 | .owner = THIS_MODULE, | |
256 | .llseek = no_llseek, | |
257 | .write = max63xx_wdt_write, | |
258 | .unlocked_ioctl = max63xx_wdt_ioctl, | |
259 | .open = max63xx_wdt_open, | |
260 | .release = max63xx_wdt_release, | |
261 | }; | |
262 | ||
263 | static struct miscdevice max63xx_wdt_miscdev = { | |
264 | .minor = WATCHDOG_MINOR, | |
265 | .name = "watchdog", | |
266 | .fops = &max63xx_wdt_fops, | |
267 | }; | |
268 | ||
269 | static int __devinit max63xx_wdt_probe(struct platform_device *pdev) | |
270 | { | |
271 | int ret = 0; | |
272 | int size; | |
273 | struct resource *res; | |
274 | struct device *dev = &pdev->dev; | |
275 | struct max63xx_timeout *table; | |
276 | ||
277 | table = (struct max63xx_timeout *)pdev->id_entry->driver_data; | |
278 | ||
279 | if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) | |
280 | heartbeat = DEFAULT_HEARTBEAT; | |
281 | ||
282 | dev_info(dev, "requesting %ds heartbeat\n", heartbeat); | |
283 | current_timeout = max63xx_select_timeout(table, heartbeat); | |
284 | ||
285 | if (!current_timeout) { | |
286 | dev_err(dev, "unable to satisfy heartbeat request\n"); | |
287 | return -EINVAL; | |
288 | } | |
289 | ||
290 | dev_info(dev, "using %ds heartbeat with %ds initial delay\n", | |
291 | current_timeout->twd, current_timeout->tdelay); | |
292 | ||
293 | heartbeat = current_timeout->twd; | |
294 | ||
295 | max63xx_pdev = pdev; | |
296 | ||
297 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
298 | if (res == NULL) { | |
299 | dev_err(dev, "failed to get memory region resource\n"); | |
300 | return -ENOENT; | |
301 | } | |
302 | ||
303 | size = resource_size(res); | |
304 | wdt_mem = request_mem_region(res->start, size, pdev->name); | |
305 | ||
306 | if (wdt_mem == NULL) { | |
307 | dev_err(dev, "failed to get memory region\n"); | |
308 | return -ENOENT; | |
309 | } | |
310 | ||
311 | wdt_base = ioremap(res->start, size); | |
312 | if (!wdt_base) { | |
313 | dev_err(dev, "failed to map memory region\n"); | |
314 | ret = -ENOMEM; | |
315 | goto out_request; | |
316 | } | |
317 | ||
318 | ret = misc_register(&max63xx_wdt_miscdev); | |
319 | if (ret < 0) { | |
320 | dev_err(dev, "cannot register misc device\n"); | |
321 | goto out_unmap; | |
322 | } | |
323 | ||
324 | return 0; | |
325 | ||
326 | out_unmap: | |
327 | iounmap(wdt_base); | |
328 | out_request: | |
329 | release_resource(wdt_mem); | |
330 | kfree(wdt_mem); | |
331 | ||
332 | return ret; | |
333 | } | |
334 | ||
335 | static int __devexit max63xx_wdt_remove(struct platform_device *pdev) | |
336 | { | |
337 | misc_deregister(&max63xx_wdt_miscdev); | |
338 | if (wdt_mem) { | |
339 | release_resource(wdt_mem); | |
340 | kfree(wdt_mem); | |
341 | wdt_mem = NULL; | |
342 | } | |
343 | ||
344 | if (wdt_base) | |
345 | iounmap(wdt_base); | |
346 | ||
347 | return 0; | |
348 | } | |
349 | ||
350 | static struct platform_device_id max63xx_id_table[] = { | |
351 | { "max6369_wdt", (kernel_ulong_t)max6369_table, }, | |
352 | { "max6370_wdt", (kernel_ulong_t)max6369_table, }, | |
353 | { "max6371_wdt", (kernel_ulong_t)max6371_table, }, | |
354 | { "max6372_wdt", (kernel_ulong_t)max6371_table, }, | |
355 | { "max6373_wdt", (kernel_ulong_t)max6373_table, }, | |
356 | { "max6374_wdt", (kernel_ulong_t)max6373_table, }, | |
357 | { }, | |
358 | }; | |
359 | MODULE_DEVICE_TABLE(platform, max63xx_id_table); | |
360 | ||
361 | static struct platform_driver max63xx_wdt_driver = { | |
362 | .probe = max63xx_wdt_probe, | |
363 | .remove = __devexit_p(max63xx_wdt_remove), | |
364 | .id_table = max63xx_id_table, | |
365 | .driver = { | |
366 | .name = "max63xx_wdt", | |
367 | .owner = THIS_MODULE, | |
368 | }, | |
369 | }; | |
370 | ||
371 | static int __init max63xx_wdt_init(void) | |
372 | { | |
373 | return platform_driver_register(&max63xx_wdt_driver); | |
374 | } | |
375 | ||
376 | static void __exit max63xx_wdt_exit(void) | |
377 | { | |
378 | platform_driver_unregister(&max63xx_wdt_driver); | |
379 | } | |
380 | ||
381 | module_init(max63xx_wdt_init); | |
382 | module_exit(max63xx_wdt_exit); | |
383 | ||
384 | MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>"); | |
385 | MODULE_DESCRIPTION("max63xx Watchdog Driver"); | |
386 | ||
387 | module_param(heartbeat, int, 0); | |
388 | MODULE_PARM_DESC(heartbeat, | |
389 | "Watchdog heartbeat period in seconds from 1 to " | |
390 | __MODULE_STRING(MAX_HEARTBEAT) ", default " | |
391 | __MODULE_STRING(DEFAULT_HEARTBEAT)); | |
392 | ||
393 | module_param(nowayout, int, 0); | |
394 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" | |
395 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
396 | ||
397 | module_param(nodelay, int, 0); | |
398 | MODULE_PARM_DESC(nodelay, | |
399 | "Force selection of a timeout setting without initial delay " | |
400 | "(max6373/74 only, default=0)"); | |
401 | ||
402 | MODULE_LICENSE("GPL"); | |
403 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |