2 * Watchdog timer for PowerPC Book-E systems
4 * Author: Matthew McClintock
5 * Maintainer: Kumar Gala <galak@kernel.crashing.org>
7 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
15 #include <linux/module.h>
17 #include <linux/smp.h>
18 #include <linux/miscdevice.h>
19 #include <linux/notifier.h>
20 #include <linux/watchdog.h>
21 #include <linux/uaccess.h>
23 #include <asm/reg_booke.h>
25 #include <asm/div64.h>
27 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
28 * Also, the wdt_period sets the watchdog timer period timeout.
29 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
30 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
31 * first time nothing will happen, the second time a watchdog exception will
32 * occur, and the final time the board will reset.
35 u32 booke_wdt_enabled;
36 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
38 #ifdef CONFIG_FSL_BOOKE
39 #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
40 #define WDTP_MASK (WDTP(0x3f))
42 #define WDTP(x) (TCR_WP(x))
43 #define WDTP_MASK (TCR_WP_MASK)
46 static DEFINE_SPINLOCK(booke_wdt_lock);
48 /* For the specified period, determine the number of seconds
49 * corresponding to the reset time. There will be a watchdog
50 * exception at approximately 3/5 of this time.
52 * The formula to calculate this is given by:
53 * 2.5 * (2^(63-period+1)) / timebase_freq
55 * In order to simplify things, we assume that period is
56 * at least 1. This will still result in a very long timeout.
58 static unsigned long long period_to_sec(unsigned int period)
60 unsigned long long tmp = 1ULL << (64 - period);
61 unsigned long tmp2 = ppc_tb_freq;
63 /* tmp may be a very large number and we don't want to overflow,
64 * so divide the timebase freq instead of multiplying tmp
73 * This procedure will find the highest period which will give a timeout
74 * greater than the one required. e.g. for a bus speed of 66666666 and
75 * and a parameter of 2 secs, then this procedure will return a value of 38.
77 static unsigned int sec_to_period(unsigned int secs)
80 for (period = 63; period > 0; period--) {
81 if (period_to_sec(period) >= secs)
87 static void __booke_wdt_set(void *data)
91 val = mfspr(SPRN_TCR);
93 val |= WDTP(booke_wdt_period);
98 static void booke_wdt_set(void)
100 on_each_cpu(__booke_wdt_set, NULL, 0);
103 static void __booke_wdt_ping(void *data)
105 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
108 static void booke_wdt_ping(void)
110 on_each_cpu(__booke_wdt_ping, NULL, 0);
113 static void __booke_wdt_enable(void *data)
117 /* clear status before enabling watchdog */
118 __booke_wdt_ping(NULL);
119 val = mfspr(SPRN_TCR);
121 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
123 mtspr(SPRN_TCR, val);
127 * booke_wdt_disable - disable the watchdog on the given CPU
129 * This function is called on each CPU. It disables the watchdog on that CPU.
131 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
132 * effectively disable the watchdog by setting its period to the maximum value.
134 static void __booke_wdt_disable(void *data)
138 val = mfspr(SPRN_TCR);
139 val &= ~(TCR_WIE | WDTP_MASK);
140 mtspr(SPRN_TCR, val);
142 /* clear status to make sure nothing is pending */
143 __booke_wdt_ping(NULL);
147 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
148 size_t count, loff_t *ppos)
154 static struct watchdog_info ident = {
155 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
156 .identity = "PowerPC Book-E Watchdog",
159 static long booke_wdt_ioctl(struct file *file,
160 unsigned int cmd, unsigned long arg)
163 u32 __user *p = (u32 __user *)arg;
166 case WDIOC_GETSUPPORT:
167 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
169 case WDIOC_GETSTATUS:
170 return put_user(0, p);
171 case WDIOC_GETBOOTSTATUS:
172 /* XXX: something is clearing TSR */
173 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
174 /* returns CARDRESET if last reset was caused by the WDT */
175 return (tmp ? WDIOF_CARDRESET : 0);
176 case WDIOC_SETOPTIONS:
177 if (get_user(tmp, p))
179 if (tmp == WDIOS_ENABLECARD) {
185 case WDIOC_KEEPALIVE:
188 case WDIOC_SETTIMEOUT:
189 if (get_user(tmp, p))
191 #ifdef CONFIG_FSL_BOOKE
192 /* period of 1 gives the largest possible timeout */
193 if (tmp > period_to_sec(1))
195 booke_wdt_period = sec_to_period(tmp);
197 booke_wdt_period = tmp;
201 case WDIOC_GETTIMEOUT:
202 #ifdef CONFIG_FSL_BOOKE
203 return put_user(period_to_sec(booke_wdt_period), p);
205 return put_user(booke_wdt_period, p);
214 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */
215 static unsigned long wdt_is_active;
217 static int booke_wdt_open(struct inode *inode, struct file *file)
219 /* /dev/watchdog can only be opened once */
220 if (test_and_set_bit(0, &wdt_is_active))
223 spin_lock(&booke_wdt_lock);
224 if (booke_wdt_enabled == 0) {
225 booke_wdt_enabled = 1;
226 on_each_cpu(__booke_wdt_enable, NULL, 0);
227 pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
228 period_to_sec(booke_wdt_period));
230 spin_unlock(&booke_wdt_lock);
232 return nonseekable_open(inode, file);
235 static int booke_wdt_release(struct inode *inode, struct file *file)
237 #ifndef CONFIG_WATCHDOG_NOWAYOUT
238 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
239 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
240 * watchdog should remain enabled. So we disable it only if
241 * CONFIG_WATCHDOG_NOWAYOUT is not defined.
243 on_each_cpu(__booke_wdt_disable, NULL, 0);
244 booke_wdt_enabled = 0;
245 pr_debug("booke_wdt: watchdog disabled\n");
248 clear_bit(0, &wdt_is_active);
253 static const struct file_operations booke_wdt_fops = {
254 .owner = THIS_MODULE,
256 .write = booke_wdt_write,
257 .unlocked_ioctl = booke_wdt_ioctl,
258 .open = booke_wdt_open,
259 .release = booke_wdt_release,
262 static struct miscdevice booke_wdt_miscdev = {
263 .minor = WATCHDOG_MINOR,
265 .fops = &booke_wdt_fops,
268 static void __exit booke_wdt_exit(void)
270 misc_deregister(&booke_wdt_miscdev);
273 static int __init booke_wdt_init(void)
277 pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n");
278 ident.firmware_version = cur_cpu_spec->pvr_value;
280 ret = misc_register(&booke_wdt_miscdev);
282 pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n",
283 WATCHDOG_MINOR, ret);
287 spin_lock(&booke_wdt_lock);
288 if (booke_wdt_enabled == 1) {
289 pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
290 period_to_sec(booke_wdt_period));
291 on_each_cpu(__booke_wdt_enable, NULL, 0);
293 spin_unlock(&booke_wdt_lock);
298 module_init(booke_wdt_init);
299 module_exit(booke_wdt_exit);
301 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
302 MODULE_LICENSE("GPL");