2 * drivers/char/watchdog/max63xx_wdt.c
4 * Driver for max63{69,70,71,72,73,74} watchdog timers
6 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
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.
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.
17 #include <linux/module.h>
18 #include <linux/moduleparam.h>
19 #include <linux/types.h>
20 #include <linux/kernel.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>
30 #include <linux/device.h>
31 #include <linux/slab.h>
33 #define DEFAULT_HEARTBEAT 60
34 #define MAX_HEARTBEAT 60
36 static int heartbeat = DEFAULT_HEARTBEAT;
37 static int nowayout = WATCHDOG_NOWAYOUT;
40 * Memory mapping: a single byte, 3 first lower bits to select bit 3
41 * to ping the watchdog.
43 #define MAX6369_WDSET (7 << 0)
44 #define MAX6369_WDI (1 << 3)
46 static DEFINE_SPINLOCK(io_lock);
48 static unsigned long wdt_status;
51 #define WDT_OK_TO_CLOSE 2
54 static struct resource *wdt_mem;
55 static void __iomem *wdt_base;
56 static struct platform_device *max63xx_pdev;
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).
67 * I also decided to remove from the tables any timeout smaller than a
68 * second, as it looked completly overkill...
71 /* Timeouts in second */
72 struct max63xx_timeout {
78 static struct max63xx_timeout max6369_table[] = {
85 static struct max63xx_timeout max6371_table[] = {
91 static struct max63xx_timeout max6373_table[] = {
100 static struct max63xx_timeout *current_timeout;
102 static struct max63xx_timeout *
103 max63xx_select_timeout(struct max63xx_timeout *table, int value)
106 if (value <= table->twd) {
107 if (nodelay && table->tdelay == 0)
120 static void max63xx_wdt_ping(void)
126 val = __raw_readb(wdt_base);
128 __raw_writeb(val | MAX6369_WDI, wdt_base);
129 __raw_writeb(val & ~MAX6369_WDI, wdt_base);
131 spin_unlock(&io_lock);
134 static void max63xx_wdt_enable(struct max63xx_timeout *entry)
138 if (test_and_set_bit(WDT_RUNNING, &wdt_status))
143 val = __raw_readb(wdt_base);
144 val &= ~MAX6369_WDSET;
146 __raw_writeb(val, wdt_base);
148 spin_unlock(&io_lock);
150 /* check for a edge triggered startup */
151 if (entry->tdelay == 0)
155 static void max63xx_wdt_disable(void)
159 __raw_writeb(3, wdt_base);
161 spin_unlock(&io_lock);
163 clear_bit(WDT_RUNNING, &wdt_status);
166 static int max63xx_wdt_open(struct inode *inode, struct file *file)
168 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
171 max63xx_wdt_enable(current_timeout);
172 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
174 return nonseekable_open(inode, file);
177 static ssize_t max63xx_wdt_write(struct file *file, const char *data,
178 size_t len, loff_t *ppos)
184 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
185 for (i = 0; i != len; i++) {
188 if (get_user(c, data + i))
192 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
202 static const struct watchdog_info ident = {
203 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
204 .identity = "max63xx Watchdog",
207 static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd,
213 case WDIOC_GETSUPPORT:
214 ret = copy_to_user((struct watchdog_info *)arg, &ident,
215 sizeof(ident)) ? -EFAULT : 0;
218 case WDIOC_GETSTATUS:
219 case WDIOC_GETBOOTSTATUS:
220 ret = put_user(0, (int *)arg);
223 case WDIOC_KEEPALIVE:
228 case WDIOC_GETTIMEOUT:
229 ret = put_user(heartbeat, (int *)arg);
235 static int max63xx_wdt_release(struct inode *inode, struct file *file)
237 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
238 max63xx_wdt_disable();
240 dev_crit(&max63xx_pdev->dev,
241 "device closed unexpectedly - timer will not stop\n");
243 clear_bit(WDT_IN_USE, &wdt_status);
244 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
249 static const struct file_operations max63xx_wdt_fops = {
250 .owner = THIS_MODULE,
252 .write = max63xx_wdt_write,
253 .unlocked_ioctl = max63xx_wdt_ioctl,
254 .open = max63xx_wdt_open,
255 .release = max63xx_wdt_release,
258 static struct miscdevice max63xx_wdt_miscdev = {
259 .minor = WATCHDOG_MINOR,
261 .fops = &max63xx_wdt_fops,
264 static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
268 struct resource *res;
269 struct device *dev = &pdev->dev;
270 struct max63xx_timeout *table;
272 table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
274 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
275 heartbeat = DEFAULT_HEARTBEAT;
277 dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
278 current_timeout = max63xx_select_timeout(table, heartbeat);
280 if (!current_timeout) {
281 dev_err(dev, "unable to satisfy heartbeat request\n");
285 dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
286 current_timeout->twd, current_timeout->tdelay);
288 heartbeat = current_timeout->twd;
292 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
294 dev_err(dev, "failed to get memory region resource\n");
298 size = resource_size(res);
299 wdt_mem = request_mem_region(res->start, size, pdev->name);
301 if (wdt_mem == NULL) {
302 dev_err(dev, "failed to get memory region\n");
306 wdt_base = ioremap(res->start, size);
308 dev_err(dev, "failed to map memory region\n");
313 ret = misc_register(&max63xx_wdt_miscdev);
315 dev_err(dev, "cannot register misc device\n");
324 release_resource(wdt_mem);
330 static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
332 misc_deregister(&max63xx_wdt_miscdev);
334 release_resource(wdt_mem);
345 static struct platform_device_id max63xx_id_table[] = {
346 { "max6369_wdt", (kernel_ulong_t)max6369_table, },
347 { "max6370_wdt", (kernel_ulong_t)max6369_table, },
348 { "max6371_wdt", (kernel_ulong_t)max6371_table, },
349 { "max6372_wdt", (kernel_ulong_t)max6371_table, },
350 { "max6373_wdt", (kernel_ulong_t)max6373_table, },
351 { "max6374_wdt", (kernel_ulong_t)max6373_table, },
354 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
356 static struct platform_driver max63xx_wdt_driver = {
357 .probe = max63xx_wdt_probe,
358 .remove = __devexit_p(max63xx_wdt_remove),
359 .id_table = max63xx_id_table,
361 .name = "max63xx_wdt",
362 .owner = THIS_MODULE,
366 static int __init max63xx_wdt_init(void)
368 return platform_driver_register(&max63xx_wdt_driver);
371 static void __exit max63xx_wdt_exit(void)
373 platform_driver_unregister(&max63xx_wdt_driver);
376 module_init(max63xx_wdt_init);
377 module_exit(max63xx_wdt_exit);
379 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
380 MODULE_DESCRIPTION("max63xx Watchdog Driver");
382 module_param(heartbeat, int, 0);
383 MODULE_PARM_DESC(heartbeat,
384 "Watchdog heartbeat period in seconds from 1 to "
385 __MODULE_STRING(MAX_HEARTBEAT) ", default "
386 __MODULE_STRING(DEFAULT_HEARTBEAT));
388 module_param(nowayout, int, 0);
389 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
390 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
392 module_param(nodelay, int, 0);
393 MODULE_PARM_DESC(nodelay,
394 "Force selection of a timeout setting without initial delay "
395 "(max6373/74 only, default=0)");
397 MODULE_LICENSE("GPL");
398 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);