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
);