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>
31 #include <linux/slab.h>
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 {
157 	u8 val;
158 
159 	spin_lock(&io_lock);
160 
161 	val = __raw_readb(wdt_base);
162 	val &= ~MAX6369_WDSET;
163 	val |= 3;
164 	__raw_writeb(val, wdt_base);
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);
404