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
37 u32 booke_wdt_enabled;
38 u32 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
48 static 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 */
period_to_sec(unsigned int period)60 static 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 */
sec_to_period(unsigned int secs)79 static 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
__booke_wdt_set(void * data)89 static 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
booke_wdt_set(void)100 static void booke_wdt_set(void)
101 {
102 on_each_cpu(__booke_wdt_set, NULL, 0);
103 }
104
__booke_wdt_ping(void * data)105 static void __booke_wdt_ping(void *data)
106 {
107 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
108 }
109
booke_wdt_ping(void)110 static void booke_wdt_ping(void)
111 {
112 on_each_cpu(__booke_wdt_ping, NULL, 0);
113 }
114
__booke_wdt_enable(void * data)115 static 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 */
__booke_wdt_disable(void * data)136 static 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
booke_wdt_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)149 static 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
156 static struct watchdog_info ident = {
157 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
158 .identity = "PowerPC Book-E Watchdog",
159 };
160
booke_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)161 static 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 */
217 static unsigned long wdt_is_active;
218
booke_wdt_open(struct inode * inode,struct file * file)219 static 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
booke_wdt_release(struct inode * inode,struct file * file)237 static 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
255 static 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
264 static struct miscdevice booke_wdt_miscdev = {
265 .minor = WATCHDOG_MINOR,
266 .name = "watchdog",
267 .fops = &booke_wdt_fops,
268 };
269
booke_wdt_exit(void)270 static void __exit booke_wdt_exit(void)
271 {
272 misc_deregister(&booke_wdt_miscdev);
273 }
274
booke_wdt_init(void)275 static 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
300 module_init(booke_wdt_init);
301 module_exit(booke_wdt_exit);
302
303 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
304 MODULE_LICENSE("GPL");
305