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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 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
26 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
27 * Also, the wdt_period sets the watchdog timer period timeout.
28 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
29 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
30 * first time nothing will happen, the second time a watchdog exception will
31 * occur, and the final time the board will reset.
32 */
33
34 #ifdef CONFIG_FSL_BOOKE
35 #define WDT_PERIOD_DEFAULT 63 /* Ex. wdt_period=28 bus=333Mhz,reset=~40sec */
36 #else
37 #define WDT_PERIOD_DEFAULT 3 /* Refer to the PPC40x and PPC4xx manuals */
38 #endif /* for timing information */
39
40 u32 booke_wdt_enabled;
41 u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
42
43 #ifdef CONFIG_FSL_BOOKE
44 #define WDTP(x) ((((63-x)&0x3)<<30)|(((63-x)&0x3c)<<15))
45 #else
46 #define WDTP(x) (TCR_WP(x))
47 #endif
48
49 static DEFINE_SPINLOCK(booke_wdt_lock);
50
51 static void __booke_wdt_ping(void *data)
52 {
53 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
54 }
55
56 static void booke_wdt_ping(void)
57 {
58 on_each_cpu(__booke_wdt_ping, NULL, 0, 0);
59 }
60
61 static void __booke_wdt_enable(void *data)
62 {
63 u32 val;
64
65 /* clear status before enabling watchdog */
66 __booke_wdt_ping(NULL);
67 val = mfspr(SPRN_TCR);
68 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
69
70 mtspr(SPRN_TCR, val);
71 }
72
73 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
74 size_t count, loff_t *ppos)
75 {
76 booke_wdt_ping();
77 return count;
78 }
79
80 static struct watchdog_info ident = {
81 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
82 .identity = "PowerPC Book-E Watchdog",
83 };
84
85 static long booke_wdt_ioctl(struct file *file,
86 unsigned int cmd, unsigned long arg)
87 {
88 u32 tmp = 0;
89 u32 __user *p = (u32 __user *)arg;
90
91 switch (cmd) {
92 case WDIOC_GETSUPPORT:
93 if (copy_to_user(arg, &ident, sizeof(struct watchdog_info)))
94 return -EFAULT;
95 case WDIOC_GETSTATUS:
96 return put_user(ident.options, p);
97 case WDIOC_GETBOOTSTATUS:
98 /* XXX: something is clearing TSR */
99 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
100 /* returns 1 if last reset was caused by the WDT */
101 return (tmp ? 1 : 0);
102 case WDIOC_KEEPALIVE:
103 booke_wdt_ping();
104 return 0;
105 case WDIOC_SETTIMEOUT:
106 if (get_user(booke_wdt_period, p))
107 return -EFAULT;
108 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP(0)) |
109 WDTP(booke_wdt_period));
110 return 0;
111 case WDIOC_GETTIMEOUT:
112 return put_user(booke_wdt_period, p);
113 case WDIOC_SETOPTIONS:
114 if (get_user(tmp, p))
115 return -EINVAL;
116 if (tmp == WDIOS_ENABLECARD) {
117 booke_wdt_ping();
118 break;
119 } else
120 return -EINVAL;
121 return 0;
122 default:
123 return -ENOTTY;
124 }
125
126 return 0;
127 }
128
129 static int booke_wdt_open(struct inode *inode, struct file *file)
130 {
131 spin_lock(&booke_wdt_lock);
132 if (booke_wdt_enabled == 0) {
133 booke_wdt_enabled = 1;
134 on_each_cpu(__booke_wdt_enable, NULL, 0, 0);
135 printk(KERN_INFO
136 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
137 booke_wdt_period);
138 }
139 spin_unlock(&booke_wdt_lock);
140
141 return nonseekable_open(inode, file);
142 }
143
144 static const struct file_operations booke_wdt_fops = {
145 .owner = THIS_MODULE,
146 .llseek = no_llseek,
147 .write = booke_wdt_write,
148 .unlocked_ioctl = booke_wdt_ioctl,
149 .open = booke_wdt_open,
150 };
151
152 static struct miscdevice booke_wdt_miscdev = {
153 .minor = WATCHDOG_MINOR,
154 .name = "watchdog",
155 .fops = &booke_wdt_fops,
156 };
157
158 static void __exit booke_wdt_exit(void)
159 {
160 misc_deregister(&booke_wdt_miscdev);
161 }
162
163 static int __init booke_wdt_init(void)
164 {
165 int ret = 0;
166
167 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
168 ident.firmware_version = cur_cpu_spec->pvr_value;
169
170 ret = misc_register(&booke_wdt_miscdev);
171 if (ret) {
172 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
173 WATCHDOG_MINOR, ret);
174 return ret;
175 }
176
177 spin_lock(&booke_wdt_lock);
178 if (booke_wdt_enabled == 1) {
179 printk(KERN_INFO
180 "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
181 booke_wdt_period);
182 on_each_cpu(__booke_wdt_enable, NULL, 0, 0);
183 }
184 spin_unlock(&booke_wdt_lock);
185
186 return ret;
187 }
188 device_initcall(booke_wdt_init);