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1/*
2 * Watchdog timer for PowerPC Book-E systems
3 *
4 * Author: Matthew McClintock
5 * Maintainer: Kumar Gala <galak@kernel.crashing.org>
6 *
7 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
8 *
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.
13 */
14
15#include <linux/module.h>
16#include <linux/fs.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>
22
23#include <asm/reg_booke.h>
24#include <asm/system.h>
25#include <asm/time.h>
26#include <asm/div64.h>
27
28/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
29 * Also, the wdt_period sets the watchdog timer period timeout.
30 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
31 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
32 * first time nothing will happen, the second time a watchdog exception will
33 * occur, and the final time the board will reset.
34 */
35
36u32 booke_wdt_enabled;
37u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
38
39#ifdef CONFIG_FSL_BOOKE
40#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
41#define WDTP_MASK (WDTP(0x3f))
42#else
43#define WDTP(x) (TCR_WP(x))
44#define WDTP_MASK (TCR_WP_MASK)
45#endif
46
47static DEFINE_SPINLOCK(booke_wdt_lock);
48
49/* For the specified period, determine the number of seconds
50 * corresponding to the reset time. There will be a watchdog
51 * exception at approximately 3/5 of this time.
52 *
53 * The formula to calculate this is given by:
54 * 2.5 * (2^(63-period+1)) / timebase_freq
55 *
56 * In order to simplify things, we assume that period is
57 * at least 1. This will still result in a very long timeout.
58 */
59static unsigned long long period_to_sec(unsigned int period)
60{
61 unsigned long long tmp = 1ULL << (64 - period);
62 unsigned long tmp2 = ppc_tb_freq;
63
64 /* tmp may be a very large number and we don't want to overflow,
65 * so divide the timebase freq instead of multiplying tmp
66 */
67 tmp2 = tmp2 / 5 * 2;
68
69 do_div(tmp, tmp2);
70 return tmp;
71}
72
73/*
74 * This procedure will find the highest period which will give a timeout
75 * greater than the one required. e.g. for a bus speed of 66666666 and
76 * and a parameter of 2 secs, then this procedure will return a value of 38.
77 */
78static unsigned int sec_to_period(unsigned int secs)
79{
80 unsigned int period;
81 for (period = 63; period > 0; period--) {
82 if (period_to_sec(period) >= secs)
83 return period;
84 }
85 return 0;
86}
87
88static void __booke_wdt_set(void *data)
89{
90 u32 val;
91
92 val = mfspr(SPRN_TCR);
93 val &= ~WDTP_MASK;
94 val |= WDTP(booke_wdt_period);
95
96 mtspr(SPRN_TCR, val);
97}
98
99static void booke_wdt_set(void)
100{
101 on_each_cpu(__booke_wdt_set, NULL, 0);
102}
103
104static void __booke_wdt_ping(void *data)
105{
106 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
107}
108
109static void booke_wdt_ping(void)
110{
111 on_each_cpu(__booke_wdt_ping, NULL, 0);
112}
113
114static void __booke_wdt_enable(void *data)
115{
116 u32 val;
117
118 /* clear status before enabling watchdog */
119 __booke_wdt_ping(NULL);
120 val = mfspr(SPRN_TCR);
121 val &= ~WDTP_MASK;
122 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
123
124 mtspr(SPRN_TCR, val);
125}
126
127/**
128 * booke_wdt_disable - disable the watchdog on the given CPU
129 *
130 * This function is called on each CPU. It disables the watchdog on that CPU.
131 *
132 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
133 * effectively disable the watchdog by setting its period to the maximum value.
134 */
135static void __booke_wdt_disable(void *data)
136{
137 u32 val;
138
139 val = mfspr(SPRN_TCR);
140 val &= ~(TCR_WIE | WDTP_MASK);
141 mtspr(SPRN_TCR, val);
142
143 /* clear status to make sure nothing is pending */
144 __booke_wdt_ping(NULL);
145
146}
147
148static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
149 size_t count, loff_t *ppos)
150{
151 booke_wdt_ping();
152 return count;
153}
154
155static struct watchdog_info ident = {
156 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
157 .identity = "PowerPC Book-E Watchdog",
158};
159
160static long booke_wdt_ioctl(struct file *file,
161 unsigned int cmd, unsigned long arg)
162{
163 u32 tmp = 0;
164 u32 __user *p = (u32 __user *)arg;
165
166 switch (cmd) {
167 case WDIOC_GETSUPPORT:
168 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
169 return -EFAULT;
170 case WDIOC_GETSTATUS:
171 return put_user(0, p);
172 case WDIOC_GETBOOTSTATUS:
173 /* XXX: something is clearing TSR */
174 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
175 /* returns CARDRESET if last reset was caused by the WDT */
176 return (tmp ? WDIOF_CARDRESET : 0);
177 case WDIOC_SETOPTIONS:
178 if (get_user(tmp, p))
179 return -EINVAL;
180 if (tmp == WDIOS_ENABLECARD) {
181 booke_wdt_ping();
182 break;
183 } else
184 return -EINVAL;
185 return 0;
186 case WDIOC_KEEPALIVE:
187 booke_wdt_ping();
188 return 0;
189 case WDIOC_SETTIMEOUT:
190 if (get_user(tmp, p))
191 return -EFAULT;
192#ifdef CONFIG_FSL_BOOKE
193 /* period of 1 gives the largest possible timeout */
194 if (tmp > period_to_sec(1))
195 return -EINVAL;
196 booke_wdt_period = sec_to_period(tmp);
197#else
198 booke_wdt_period = tmp;
199#endif
200 booke_wdt_set();
201 return 0;
202 case WDIOC_GETTIMEOUT:
203 return put_user(booke_wdt_period, p);
204 default:
205 return -ENOTTY;
206 }
207
208 return 0;
209}
210
211/* wdt_is_active stores wether or not the /dev/watchdog device is opened */
212static unsigned long wdt_is_active;
213
214static int booke_wdt_open(struct inode *inode, struct file *file)
215{
216 /* /dev/watchdog can only be opened once */
217 if (test_and_set_bit(0, &wdt_is_active))
218 return -EBUSY;
219
220 spin_lock(&booke_wdt_lock);
221 if (booke_wdt_enabled == 0) {
222 booke_wdt_enabled = 1;
223 on_each_cpu(__booke_wdt_enable, NULL, 0);
224 pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
225 period_to_sec(booke_wdt_period));
226 }
227 spin_unlock(&booke_wdt_lock);
228
229 return nonseekable_open(inode, file);
230}
231
232static int booke_wdt_release(struct inode *inode, struct file *file)
233{
234#ifndef CONFIG_WATCHDOG_NOWAYOUT
235 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
236 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
237 * watchdog should remain enabled. So we disable it only if
238 * CONFIG_WATCHDOG_NOWAYOUT is not defined.
239 */
240 on_each_cpu(__booke_wdt_disable, NULL, 0);
241 booke_wdt_enabled = 0;
242 pr_debug("booke_wdt: watchdog disabled\n");
243#endif
244
245 clear_bit(0, &wdt_is_active);
246
247 return 0;
248}
249
250static const struct file_operations booke_wdt_fops = {
251 .owner = THIS_MODULE,
252 .llseek = no_llseek,
253 .write = booke_wdt_write,
254 .unlocked_ioctl = booke_wdt_ioctl,
255 .open = booke_wdt_open,
256 .release = booke_wdt_release,
257};
258
259static struct miscdevice booke_wdt_miscdev = {
260 .minor = WATCHDOG_MINOR,
261 .name = "watchdog",
262 .fops = &booke_wdt_fops,
263};
264
265static void __exit booke_wdt_exit(void)
266{
267 misc_deregister(&booke_wdt_miscdev);
268}
269
270static int __init booke_wdt_init(void)
271{
272 int ret = 0;
273
274 pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n");
275 ident.firmware_version = cur_cpu_spec->pvr_value;
276
277 ret = misc_register(&booke_wdt_miscdev);
278 if (ret) {
279 pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n",
280 WATCHDOG_MINOR, ret);
281 return ret;
282 }
283
284 spin_lock(&booke_wdt_lock);
285 if (booke_wdt_enabled == 1) {
286 pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
287 period_to_sec(booke_wdt_period));
288 on_each_cpu(__booke_wdt_enable, NULL, 0);
289 }
290 spin_unlock(&booke_wdt_lock);
291
292 return ret;
293}
294
295module_init(booke_wdt_init);
296module_exit(booke_wdt_exit);
297
298MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
299MODULE_LICENSE("GPL");
1/*
2 * Watchdog timer for PowerPC Book-E systems
3 *
4 * Author: Matthew McClintock
5 * Maintainer: Kumar Gala <galak@kernel.crashing.org>
6 *
7 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
8 *
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.
13 */
14
15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17#include <linux/module.h>
18#include <linux/fs.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>
24
25#include <asm/reg_booke.h>
26#include <asm/time.h>
27#include <asm/div64.h>
28
29/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
30 * Also, the wdt_period sets the watchdog timer period timeout.
31 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
32 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
33 * first time nothing will happen, the second time a watchdog exception will
34 * occur, and the final time the board will reset.
35 */
36
37u32 booke_wdt_enabled;
38u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
39
40#ifdef CONFIG_FSL_BOOKE
41#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
42#define WDTP_MASK (WDTP(0x3f))
43#else
44#define WDTP(x) (TCR_WP(x))
45#define WDTP_MASK (TCR_WP_MASK)
46#endif
47
48static DEFINE_SPINLOCK(booke_wdt_lock);
49
50/* For the specified period, determine the number of seconds
51 * corresponding to the reset time. There will be a watchdog
52 * exception at approximately 3/5 of this time.
53 *
54 * The formula to calculate this is given by:
55 * 2.5 * (2^(63-period+1)) / timebase_freq
56 *
57 * In order to simplify things, we assume that period is
58 * at least 1. This will still result in a very long timeout.
59 */
60static unsigned long long period_to_sec(unsigned int period)
61{
62 unsigned long long tmp = 1ULL << (64 - period);
63 unsigned long tmp2 = ppc_tb_freq;
64
65 /* tmp may be a very large number and we don't want to overflow,
66 * so divide the timebase freq instead of multiplying tmp
67 */
68 tmp2 = tmp2 / 5 * 2;
69
70 do_div(tmp, tmp2);
71 return tmp;
72}
73
74/*
75 * This procedure will find the highest period which will give a timeout
76 * greater than the one required. e.g. for a bus speed of 66666666 and
77 * and a parameter of 2 secs, then this procedure will return a value of 38.
78 */
79static unsigned int sec_to_period(unsigned int secs)
80{
81 unsigned int period;
82 for (period = 63; period > 0; period--) {
83 if (period_to_sec(period) >= secs)
84 return period;
85 }
86 return 0;
87}
88
89static void __booke_wdt_set(void *data)
90{
91 u32 val;
92
93 val = mfspr(SPRN_TCR);
94 val &= ~WDTP_MASK;
95 val |= WDTP(booke_wdt_period);
96
97 mtspr(SPRN_TCR, val);
98}
99
100static void booke_wdt_set(void)
101{
102 on_each_cpu(__booke_wdt_set, NULL, 0);
103}
104
105static void __booke_wdt_ping(void *data)
106{
107 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
108}
109
110static void booke_wdt_ping(void)
111{
112 on_each_cpu(__booke_wdt_ping, NULL, 0);
113}
114
115static void __booke_wdt_enable(void *data)
116{
117 u32 val;
118
119 /* clear status before enabling watchdog */
120 __booke_wdt_ping(NULL);
121 val = mfspr(SPRN_TCR);
122 val &= ~WDTP_MASK;
123 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
124
125 mtspr(SPRN_TCR, val);
126}
127
128/**
129 * booke_wdt_disable - disable the watchdog on the given CPU
130 *
131 * This function is called on each CPU. It disables the watchdog on that CPU.
132 *
133 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
134 * effectively disable the watchdog by setting its period to the maximum value.
135 */
136static void __booke_wdt_disable(void *data)
137{
138 u32 val;
139
140 val = mfspr(SPRN_TCR);
141 val &= ~(TCR_WIE | WDTP_MASK);
142 mtspr(SPRN_TCR, val);
143
144 /* clear status to make sure nothing is pending */
145 __booke_wdt_ping(NULL);
146
147}
148
149static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
150 size_t count, loff_t *ppos)
151{
152 booke_wdt_ping();
153 return count;
154}
155
156static struct watchdog_info ident = {
157 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
158 .identity = "PowerPC Book-E Watchdog",
159};
160
161static long booke_wdt_ioctl(struct file *file,
162 unsigned int cmd, unsigned long arg)
163{
164 u32 tmp = 0;
165 u32 __user *p = (u32 __user *)arg;
166
167 switch (cmd) {
168 case WDIOC_GETSUPPORT:
169 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
170 return -EFAULT;
171 case WDIOC_GETSTATUS:
172 return put_user(0, p);
173 case WDIOC_GETBOOTSTATUS:
174 /* XXX: something is clearing TSR */
175 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
176 /* returns CARDRESET if last reset was caused by the WDT */
177 return (tmp ? WDIOF_CARDRESET : 0);
178 case WDIOC_SETOPTIONS:
179 if (get_user(tmp, p))
180 return -EINVAL;
181 if (tmp == WDIOS_ENABLECARD) {
182 booke_wdt_ping();
183 break;
184 } else
185 return -EINVAL;
186 return 0;
187 case WDIOC_KEEPALIVE:
188 booke_wdt_ping();
189 return 0;
190 case WDIOC_SETTIMEOUT:
191 if (get_user(tmp, p))
192 return -EFAULT;
193#ifdef CONFIG_FSL_BOOKE
194 /* period of 1 gives the largest possible timeout */
195 if (tmp > period_to_sec(1))
196 return -EINVAL;
197 booke_wdt_period = sec_to_period(tmp);
198#else
199 booke_wdt_period = tmp;
200#endif
201 booke_wdt_set();
202 /* Fall */
203 case WDIOC_GETTIMEOUT:
204#ifdef CONFIG_FSL_BOOKE
205 return put_user(period_to_sec(booke_wdt_period), p);
206#else
207 return put_user(booke_wdt_period, p);
208#endif
209 default:
210 return -ENOTTY;
211 }
212
213 return 0;
214}
215
216/* wdt_is_active stores wether or not the /dev/watchdog device is opened */
217static unsigned long wdt_is_active;
218
219static int booke_wdt_open(struct inode *inode, struct file *file)
220{
221 /* /dev/watchdog can only be opened once */
222 if (test_and_set_bit(0, &wdt_is_active))
223 return -EBUSY;
224
225 spin_lock(&booke_wdt_lock);
226 if (booke_wdt_enabled == 0) {
227 booke_wdt_enabled = 1;
228 on_each_cpu(__booke_wdt_enable, NULL, 0);
229 pr_debug("watchdog enabled (timeout = %llu sec)\n",
230 period_to_sec(booke_wdt_period));
231 }
232 spin_unlock(&booke_wdt_lock);
233
234 return nonseekable_open(inode, file);
235}
236
237static int booke_wdt_release(struct inode *inode, struct file *file)
238{
239#ifndef CONFIG_WATCHDOG_NOWAYOUT
240 /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
241 * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
242 * watchdog should remain enabled. So we disable it only if
243 * CONFIG_WATCHDOG_NOWAYOUT is not defined.
244 */
245 on_each_cpu(__booke_wdt_disable, NULL, 0);
246 booke_wdt_enabled = 0;
247 pr_debug("watchdog disabled\n");
248#endif
249
250 clear_bit(0, &wdt_is_active);
251
252 return 0;
253}
254
255static const struct file_operations booke_wdt_fops = {
256 .owner = THIS_MODULE,
257 .llseek = no_llseek,
258 .write = booke_wdt_write,
259 .unlocked_ioctl = booke_wdt_ioctl,
260 .open = booke_wdt_open,
261 .release = booke_wdt_release,
262};
263
264static struct miscdevice booke_wdt_miscdev = {
265 .minor = WATCHDOG_MINOR,
266 .name = "watchdog",
267 .fops = &booke_wdt_fops,
268};
269
270static void __exit booke_wdt_exit(void)
271{
272 misc_deregister(&booke_wdt_miscdev);
273}
274
275static int __init booke_wdt_init(void)
276{
277 int ret = 0;
278
279 pr_info("powerpc book-e watchdog driver loaded\n");
280 ident.firmware_version = cur_cpu_spec->pvr_value;
281
282 ret = misc_register(&booke_wdt_miscdev);
283 if (ret) {
284 pr_err("cannot register device (minor=%u, ret=%i)\n",
285 WATCHDOG_MINOR, ret);
286 return ret;
287 }
288
289 spin_lock(&booke_wdt_lock);
290 if (booke_wdt_enabled == 1) {
291 pr_info("watchdog enabled (timeout = %llu sec)\n",
292 period_to_sec(booke_wdt_period));
293 on_each_cpu(__booke_wdt_enable, NULL, 0);
294 }
295 spin_unlock(&booke_wdt_lock);
296
297 return ret;
298}
299
300module_init(booke_wdt_init);
301module_exit(booke_wdt_exit);
302
303MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
304MODULE_LICENSE("GPL");