xref: /openbmc/linux/drivers/watchdog/booke_wdt.c (revision 9ac8d3fb)
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);
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_SETOPTIONS:
103 		if (get_user(tmp, p))
104 			return -EINVAL;
105 		if (tmp == WDIOS_ENABLECARD) {
106 			booke_wdt_ping();
107 			break;
108 		} else
109 			return -EINVAL;
110 		return 0;
111 	case WDIOC_KEEPALIVE:
112 		booke_wdt_ping();
113 		return 0;
114 	case WDIOC_SETTIMEOUT:
115 		if (get_user(booke_wdt_period, p))
116 			return -EFAULT;
117 		mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP(0)) |
118 						WDTP(booke_wdt_period));
119 		return 0;
120 	case WDIOC_GETTIMEOUT:
121 		return put_user(booke_wdt_period, p);
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);
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);
183 	}
184 	spin_unlock(&booke_wdt_lock);
185 
186 	return ret;
187 }
188 device_initcall(booke_wdt_init);
189