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>
32 #define DEFAULT_HEARTBEAT 60
33 #define MAX_HEARTBEAT 60
35 static int heartbeat = DEFAULT_HEARTBEAT;
36 static int nowayout = WATCHDOG_NOWAYOUT;
39 * Memory mapping: a single byte, 3 first lower bits to select bit 3
40 * to ping the watchdog.
42 #define MAX6369_WDSET (7 << 0)
43 #define MAX6369_WDI (1 << 3)
45 static DEFINE_SPINLOCK(io_lock);
47 static unsigned long wdt_status;
50 #define WDT_OK_TO_CLOSE 2
53 static struct resource *wdt_mem;
54 static void __iomem *wdt_base;
55 static struct platform_device *max63xx_pdev;
58 * The timeout values used are actually the absolute minimum the chip
59 * offers. Typical values on my board are slightly over twice as long
60 * (10s setting ends up with a 25s timeout), and can be up to 3 times
61 * the nominal setting (according to the datasheet). So please take
62 * these values with a grain of salt. Same goes for the initial delay
63 * "feature". Only max6373/74 have a few settings without this initial
64 * delay (selected with the "nodelay" parameter).
66 * I also decided to remove from the tables any timeout smaller than a
67 * second, as it looked completly overkill...
70 /* Timeouts in second */
71 struct max63xx_timeout {
77 static struct max63xx_timeout max6369_table[] = {
84 static struct max63xx_timeout max6371_table[] = {
90 static struct max63xx_timeout max6373_table[] = {
99 static struct max63xx_timeout *current_timeout;
101 static struct max63xx_timeout *
102 max63xx_select_timeout(struct max63xx_timeout *table, int value)
105 if (value <= table->twd) {
106 if (nodelay && table->tdelay == 0)
119 static void max63xx_wdt_ping(void)
125 val = __raw_readb(wdt_base);
127 __raw_writeb(val | MAX6369_WDI, wdt_base);
128 __raw_writeb(val & ~MAX6369_WDI, wdt_base);
130 spin_unlock(&io_lock);
133 static void max63xx_wdt_enable(struct max63xx_timeout *entry)
137 if (test_and_set_bit(WDT_RUNNING, &wdt_status))
142 val = __raw_readb(wdt_base);
143 val &= ~MAX6369_WDSET;
145 __raw_writeb(val, wdt_base);
147 spin_unlock(&io_lock);
149 /* check for a edge triggered startup */
150 if (entry->tdelay == 0)
154 static void max63xx_wdt_disable(void)
158 __raw_writeb(3, wdt_base);
160 spin_unlock(&io_lock);
162 clear_bit(WDT_RUNNING, &wdt_status);
165 static int max63xx_wdt_open(struct inode *inode, struct file *file)
167 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
170 max63xx_wdt_enable(current_timeout);
171 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
173 return nonseekable_open(inode, file);
176 static ssize_t max63xx_wdt_write(struct file *file, const char *data,
177 size_t len, loff_t *ppos)
183 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
184 for (i = 0; i != len; i++) {
187 if (get_user(c, data + i))
191 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
201 static const struct watchdog_info ident = {
202 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
203 .identity = "max63xx Watchdog",
206 static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd,
212 case WDIOC_GETSUPPORT:
213 ret = copy_to_user((struct watchdog_info *)arg, &ident,
214 sizeof(ident)) ? -EFAULT : 0;
217 case WDIOC_GETSTATUS:
218 case WDIOC_GETBOOTSTATUS:
219 ret = put_user(0, (int *)arg);
222 case WDIOC_KEEPALIVE:
227 case WDIOC_GETTIMEOUT:
228 ret = put_user(heartbeat, (int *)arg);
234 static int max63xx_wdt_release(struct inode *inode, struct file *file)
236 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
237 max63xx_wdt_disable();
239 dev_crit(&max63xx_pdev->dev,
240 "device closed unexpectedly - timer will not stop\n");
242 clear_bit(WDT_IN_USE, &wdt_status);
243 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
248 static const struct file_operations max63xx_wdt_fops = {
249 .owner = THIS_MODULE,
251 .write = max63xx_wdt_write,
252 .unlocked_ioctl = max63xx_wdt_ioctl,
253 .open = max63xx_wdt_open,
254 .release = max63xx_wdt_release,
257 static struct miscdevice max63xx_wdt_miscdev = {
258 .minor = WATCHDOG_MINOR,
260 .fops = &max63xx_wdt_fops,
263 static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
267 struct resource *res;
268 struct device *dev = &pdev->dev;
269 struct max63xx_timeout *table;
271 table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
273 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
274 heartbeat = DEFAULT_HEARTBEAT;
276 dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
277 current_timeout = max63xx_select_timeout(table, heartbeat);
279 if (!current_timeout) {
280 dev_err(dev, "unable to satisfy heartbeat request\n");
284 dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
285 current_timeout->twd, current_timeout->tdelay);
287 heartbeat = current_timeout->twd;
291 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
293 dev_err(dev, "failed to get memory region resource\n");
297 size = resource_size(res);
298 wdt_mem = request_mem_region(res->start, size, pdev->name);
300 if (wdt_mem == NULL) {
301 dev_err(dev, "failed to get memory region\n");
305 wdt_base = ioremap(res->start, size);
307 dev_err(dev, "failed to map memory region\n");
312 ret = misc_register(&max63xx_wdt_miscdev);
314 dev_err(dev, "cannot register misc device\n");
323 release_resource(wdt_mem);
329 static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
331 misc_deregister(&max63xx_wdt_miscdev);
333 release_resource(wdt_mem);
344 static struct platform_device_id max63xx_id_table[] = {
345 { "max6369_wdt", (kernel_ulong_t)max6369_table, },
346 { "max6370_wdt", (kernel_ulong_t)max6369_table, },
347 { "max6371_wdt", (kernel_ulong_t)max6371_table, },
348 { "max6372_wdt", (kernel_ulong_t)max6371_table, },
349 { "max6373_wdt", (kernel_ulong_t)max6373_table, },
350 { "max6374_wdt", (kernel_ulong_t)max6373_table, },
353 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
355 static struct platform_driver max63xx_wdt_driver = {
356 .probe = max63xx_wdt_probe,
357 .remove = __devexit_p(max63xx_wdt_remove),
358 .id_table = max63xx_id_table,
360 .name = "max63xx_wdt",
361 .owner = THIS_MODULE,
365 static int __init max63xx_wdt_init(void)
367 return platform_driver_register(&max63xx_wdt_driver);
370 static void __exit max63xx_wdt_exit(void)
372 platform_driver_unregister(&max63xx_wdt_driver);
375 module_init(max63xx_wdt_init);
376 module_exit(max63xx_wdt_exit);
378 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
379 MODULE_DESCRIPTION("max63xx Watchdog Driver");
381 module_param(heartbeat, int, 0);
382 MODULE_PARM_DESC(heartbeat,
383 "Watchdog heartbeat period in seconds from 1 to "
384 __MODULE_STRING(MAX_HEARTBEAT) ", default "
385 __MODULE_STRING(DEFAULT_HEARTBEAT));
387 module_param(nowayout, int, 0);
388 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
389 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
391 module_param(nodelay, int, 0);
392 MODULE_PARM_DESC(nodelay,
393 "Force selection of a timeout setting without initial delay "
394 "(max6373/74 only, default=0)");
396 MODULE_LICENSE("GPL");
397 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);