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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 #include <linux/module.h>
19 #include <linux/smp.h>
20 #include <linux/miscdevice.h>
21 #include <linux/notifier.h>
22 #include <linux/watchdog.h>
23 #include <linux/uaccess.h>
25 #include <asm/reg_booke.h>
26 #include <asm/system.h>
28 #include <asm/div64.h>
30 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
31 * Also, the wdt_period sets the watchdog timer period timeout.
32 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
33 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
34 * first time nothing will happen, the second time a watchdog exception will
35 * occur, and the final time the board will reset.
38 u32 booke_wdt_enabled;
39 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
41 #ifdef CONFIG_FSL_BOOKE
42 #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
43 #define WDTP_MASK (WDTP(0x3f))
45 #define WDTP(x) (TCR_WP(x))
46 #define WDTP_MASK (TCR_WP_MASK)
49 static DEFINE_SPINLOCK(booke_wdt_lock);
51 /* For the specified period, determine the number of seconds
52 * corresponding to the reset time. There will be a watchdog
53 * exception at approximately 3/5 of this time.
55 * The formula to calculate this is given by:
56 * 2.5 * (2^(63-period+1)) / timebase_freq
58 * In order to simplify things, we assume that period is
59 * at least 1. This will still result in a very long timeout.
61 static unsigned long long period_to_sec(unsigned int period)
63 unsigned long long tmp = 1ULL << (64 - period);
64 unsigned long tmp2 = ppc_tb_freq;
66 /* tmp may be a very large number and we don't want to overflow,
67 * so divide the timebase freq instead of multiplying tmp
76 * This procedure will find the highest period which will give a timeout
77 * greater than the one required. e.g. for a bus speed of 66666666 and
78 * and a parameter of 2 secs, then this procedure will return a value of 38.
80 static unsigned int sec_to_period(unsigned int secs)
83 for (period = 63; period > 0; period--) {
84 if (period_to_sec(period) >= secs)
90 static void __booke_wdt_set(void *data)
94 val = mfspr(SPRN_TCR);
96 val |= WDTP(booke_wdt_period);
101 static void booke_wdt_set(void)
103 on_each_cpu(__booke_wdt_set, NULL, 0);
106 static void __booke_wdt_ping(void *data)
108 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
111 static void booke_wdt_ping(void)
113 on_each_cpu(__booke_wdt_ping, NULL, 0);
116 static void __booke_wdt_enable(void *data)
120 /* clear status before enabling watchdog */
121 __booke_wdt_ping(NULL);
122 val = mfspr(SPRN_TCR);
124 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
126 mtspr(SPRN_TCR, val);
130 * booke_wdt_disable - disable the watchdog on the given CPU
132 * This function is called on each CPU. It disables the watchdog on that CPU.
134 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
135 * effectively disable the watchdog by setting its period to the maximum value.
137 static void __booke_wdt_disable(void *data)
141 val = mfspr(SPRN_TCR);
142 val &= ~(TCR_WIE | WDTP_MASK);
143 mtspr(SPRN_TCR, val);
145 /* clear status to make sure nothing is pending */
146 __booke_wdt_ping(NULL);
150 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
151 size_t count, loff_t *ppos)
157 static struct watchdog_info ident = {
158 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
159 .identity = "PowerPC Book-E Watchdog",
162 static long booke_wdt_ioctl(struct file *file,
163 unsigned int cmd, unsigned long arg)
166 u32 __user *p = (u32 __user *)arg;
169 case WDIOC_GETSUPPORT:
170 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
172 case WDIOC_GETSTATUS:
173 return put_user(0, p);
174 case WDIOC_GETBOOTSTATUS:
175 /* XXX: something is clearing TSR */
176 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
177 /* returns CARDRESET if last reset was caused by the WDT */
178 return (tmp ? WDIOF_CARDRESET : 0);
179 case WDIOC_SETOPTIONS:
180 if (get_user(tmp, p))
182 if (tmp == WDIOS_ENABLECARD) {
188 case WDIOC_KEEPALIVE:
191 case WDIOC_SETTIMEOUT:
192 if (get_user(tmp, p))
194 #ifdef CONFIG_FSL_BOOKE
195 /* period of 1 gives the largest possible timeout */
196 if (tmp > period_to_sec(1))
198 booke_wdt_period = sec_to_period(tmp);
200 booke_wdt_period = tmp;
204 case WDIOC_GETTIMEOUT:
205 #ifdef CONFIG_FSL_BOOKE
206 return put_user(period_to_sec(booke_wdt_period), p);
208 return put_user(booke_wdt_period, p);
217 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */
218 static unsigned long wdt_is_active;
220 static int booke_wdt_open(struct inode *inode, struct file *file)
222 /* /dev/watchdog can only be opened once */
223 if (test_and_set_bit(0, &wdt_is_active))
226 spin_lock(&booke_wdt_lock);
227 if (booke_wdt_enabled == 0) {
228 booke_wdt_enabled = 1;
229 on_each_cpu(__booke_wdt_enable, NULL, 0);
230 pr_debug("watchdog enabled (timeout = %llu sec)\n",
231 period_to_sec(booke_wdt_period));
233 spin_unlock(&booke_wdt_lock);
235 return nonseekable_open(inode, file);
238 static int booke_wdt_release(struct inode *inode, struct file *file)
240 #ifndef CONFIG_WATCHDOG_NOWAYOUT
241 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
242 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
243 * watchdog should remain enabled. So we disable it only if
244 * CONFIG_WATCHDOG_NOWAYOUT is not defined.
246 on_each_cpu(__booke_wdt_disable, NULL, 0);
247 booke_wdt_enabled = 0;
248 pr_debug("watchdog disabled\n");
251 clear_bit(0, &wdt_is_active);
256 static const struct file_operations booke_wdt_fops = {
257 .owner = THIS_MODULE,
259 .write = booke_wdt_write,
260 .unlocked_ioctl = booke_wdt_ioctl,
261 .open = booke_wdt_open,
262 .release = booke_wdt_release,
265 static struct miscdevice booke_wdt_miscdev = {
266 .minor = WATCHDOG_MINOR,
268 .fops = &booke_wdt_fops,
271 static void __exit booke_wdt_exit(void)
273 misc_deregister(&booke_wdt_miscdev);
276 static int __init booke_wdt_init(void)
280 pr_info("powerpc book-e watchdog driver loaded\n");
281 ident.firmware_version = cur_cpu_spec->pvr_value;
283 ret = misc_register(&booke_wdt_miscdev);
285 pr_err("cannot register device (minor=%u, ret=%i)\n",
286 WATCHDOG_MINOR, ret);
290 spin_lock(&booke_wdt_lock);
291 if (booke_wdt_enabled == 1) {
292 pr_info("watchdog enabled (timeout = %llu sec)\n",
293 period_to_sec(booke_wdt_period));
294 on_each_cpu(__booke_wdt_enable, NULL, 0);
296 spin_unlock(&booke_wdt_lock);
301 module_init(booke_wdt_init);
302 module_exit(booke_wdt_exit);
304 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
305 MODULE_LICENSE("GPL");