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
36 u32 booke_wdt_enabled;
37 u32 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
47 static 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 */
period_to_sec(unsigned int period)59 static 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 */
sec_to_period(unsigned int secs)78 static 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
__booke_wdt_set(void * data)88 static 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
booke_wdt_set(void)99 static void booke_wdt_set(void)
100 {
101 on_each_cpu(__booke_wdt_set, NULL, 0);
102 }
103
__booke_wdt_ping(void * data)104 static void __booke_wdt_ping(void *data)
105 {
106 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
107 }
108
booke_wdt_ping(void)109 static void booke_wdt_ping(void)
110 {
111 on_each_cpu(__booke_wdt_ping, NULL, 0);
112 }
113
__booke_wdt_enable(void * data)114 static 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 */
__booke_wdt_disable(void * data)135 static 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
booke_wdt_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)148 static 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
155 static struct watchdog_info ident = {
156 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
157 .identity = "PowerPC Book-E Watchdog",
158 };
159
booke_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)160 static 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 */
212 static unsigned long wdt_is_active;
213
booke_wdt_open(struct inode * inode,struct file * file)214 static 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
booke_wdt_release(struct inode * inode,struct file * file)232 static 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
250 static 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
259 static struct miscdevice booke_wdt_miscdev = {
260 .minor = WATCHDOG_MINOR,
261 .name = "watchdog",
262 .fops = &booke_wdt_fops,
263 };
264
booke_wdt_exit(void)265 static void __exit booke_wdt_exit(void)
266 {
267 misc_deregister(&booke_wdt_miscdev);
268 }
269
booke_wdt_init(void)270 static 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
295 module_init(booke_wdt_init);
296 module_exit(booke_wdt_exit);
297
298 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
299 MODULE_LICENSE("GPL");
300