drivers/watchdog/sb_wdog.c

2  * Watchdog driver for SiByte SB1 SoCs
16  * It is a simple timer, and there is an interrupt that is raised the
17  * first time the timer expires.  The second time it expires, the chip
26  * The timer takes 23 bits of a 64 bit register (?) as a count value,
30  * This watchdog borrows some user semantics from the softdog driver,
31  * in that if you close the fd, it leaves the watchdog running, unless
33  * the watchdog when you close the fd like some other drivers.
35  * Based on various other watchdog drivers, which are probably all
55 #include <linux/watchdog.h>
66  * set the initial count value of a timer
74 	__raw_writeq(t & 0x7fffffUL, wdog - 0x10);  in sbwdog_set()
79  * cause the timer to [re]load it's initial count and start counting
100 	.identity	= "SiByte Watchdog",
110 		return -EBUSY;  in sbwdog_open()
114 	 * Activate the timer  in sbwdog_open()
131 		pr_crit("%s: Unexpected close, not stopping watchdog!\n",  in sbwdog_release()
142  * 42 - the answer
151 		 * restart the timer  in sbwdog_write()
159 				return -EFAULT;  in sbwdog_write()
172 	int ret = -ENOTTY;  in sbwdog_ioctl()
179 		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;  in sbwdog_ioctl()
199 			ret = -EINVAL;  in sbwdog_ioctl()
212 		ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p);  in sbwdog_ioctl()
246 	.name		= "watchdog",
258  * code can use it to re-up the watchdog, thereby saving the kernel from
259  * having to create and maintain a timer, just to tickle another timer,
269 	wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;  in sbwdog_interrupt()
272 	 * if it's the second watchdog timer, it's for those users  in sbwdog_interrupt()
308 		pr_err("%s: failed to request irq 1 - %d\n",  in sbwdog_init()
338 MODULE_DESCRIPTION("SiByte Watchdog");
342       "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
348  * first watchdog timer for the kernels own purpose.
355 		"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
357 		pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret);