xref: /openbmc/linux/drivers/watchdog/m54xx_wdt.c (revision 4800cd83)
1 /*
2  * drivers/watchdog/m54xx_wdt.c
3  *
4  * Watchdog driver for ColdFire MCF547x & MCF548x processors
5  * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
6  *
7  * Adapted from the IXP4xx watchdog driver, which carries these notices:
8  *
9  *  Author: Deepak Saxena <dsaxena@plexity.net>
10  *
11  *  Copyright 2004 (c) MontaVista, Software, Inc.
12  *  Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
13  *
14  * This file is licensed under  the terms of the GNU General Public
15  * License version 2. This program is licensed "as is" without any
16  * warranty of any kind, whether express or implied.
17  */
18 
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/fs.h>
24 #include <linux/miscdevice.h>
25 #include <linux/watchdog.h>
26 #include <linux/init.h>
27 #include <linux/bitops.h>
28 #include <linux/ioport.h>
29 #include <linux/uaccess.h>
30 
31 #include <asm/coldfire.h>
32 #include <asm/m54xxsim.h>
33 #include <asm/m54xxgpt.h>
34 
35 static int nowayout = WATCHDOG_NOWAYOUT;
36 static unsigned int heartbeat = 30;	/* (secs) Default is 0.5 minute */
37 static unsigned long wdt_status;
38 
39 #define	WDT_IN_USE		0
40 #define	WDT_OK_TO_CLOSE		1
41 
42 static void wdt_enable(void)
43 {
44 	unsigned int gms0;
45 
46 	/* preserve GPIO usage, if any */
47 	gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
48 	if (gms0 & MCF_GPT_GMS_TMS_GPIO)
49 		gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
50 							| MCF_GPT_GMS_OD);
51 	else
52 		gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
53 	__raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
54 	__raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
55 			MCF_GPT_GCIR_CNT(0xffff), MCF_MBAR + MCF_GPT_GCIR0);
56 	gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
57 	__raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
58 }
59 
60 static void wdt_disable(void)
61 {
62 	unsigned int gms0;
63 
64 	/* disable watchdog */
65 	gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
66 	gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
67 	__raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
68 }
69 
70 static void wdt_keepalive(void)
71 {
72 	unsigned int gms0;
73 
74 	gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
75 	gms0 |= MCF_GPT_GMS_OCPW(0xA5);
76 	__raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
77 }
78 
79 static int m54xx_wdt_open(struct inode *inode, struct file *file)
80 {
81 	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
82 		return -EBUSY;
83 
84 	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
85 	wdt_enable();
86 	return nonseekable_open(inode, file);
87 }
88 
89 static ssize_t m54xx_wdt_write(struct file *file, const char *data,
90 						size_t len, loff_t *ppos)
91 {
92 	if (len) {
93 		if (!nowayout) {
94 			size_t i;
95 
96 			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
97 
98 			for (i = 0; i != len; i++) {
99 				char c;
100 
101 				if (get_user(c, data + i))
102 					return -EFAULT;
103 				if (c == 'V')
104 					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
105 			}
106 		}
107 		wdt_keepalive();
108 	}
109 	return len;
110 }
111 
112 static const struct watchdog_info ident = {
113 	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
114 				WDIOF_KEEPALIVEPING,
115 	.identity	= "Coldfire M54xx Watchdog",
116 };
117 
118 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
119 							 unsigned long arg)
120 {
121 	int ret = -ENOTTY;
122 	int time;
123 
124 	switch (cmd) {
125 	case WDIOC_GETSUPPORT:
126 		ret = copy_to_user((struct watchdog_info *)arg, &ident,
127 				   sizeof(ident)) ? -EFAULT : 0;
128 		break;
129 
130 	case WDIOC_GETSTATUS:
131 		ret = put_user(0, (int *)arg);
132 		break;
133 
134 	case WDIOC_GETBOOTSTATUS:
135 		ret = put_user(0, (int *)arg);
136 		break;
137 
138 	case WDIOC_KEEPALIVE:
139 		wdt_keepalive();
140 		ret = 0;
141 		break;
142 
143 	case WDIOC_SETTIMEOUT:
144 		ret = get_user(time, (int *)arg);
145 		if (ret)
146 			break;
147 
148 		if (time <= 0 || time > 30) {
149 			ret = -EINVAL;
150 			break;
151 		}
152 
153 		heartbeat = time;
154 		wdt_enable();
155 		/* Fall through */
156 
157 	case WDIOC_GETTIMEOUT:
158 		ret = put_user(heartbeat, (int *)arg);
159 		break;
160 	}
161 	return ret;
162 }
163 
164 static int m54xx_wdt_release(struct inode *inode, struct file *file)
165 {
166 	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
167 		wdt_disable();
168 	else {
169 		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
170 					"timer will not stop\n");
171 		wdt_keepalive();
172 	}
173 	clear_bit(WDT_IN_USE, &wdt_status);
174 	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
175 
176 	return 0;
177 }
178 
179 
180 static const struct file_operations m54xx_wdt_fops = {
181 	.owner		= THIS_MODULE,
182 	.llseek		= no_llseek,
183 	.write		= m54xx_wdt_write,
184 	.unlocked_ioctl	= m54xx_wdt_ioctl,
185 	.open		= m54xx_wdt_open,
186 	.release	= m54xx_wdt_release,
187 };
188 
189 static struct miscdevice m54xx_wdt_miscdev = {
190 	.minor		= WATCHDOG_MINOR,
191 	.name		= "watchdog",
192 	.fops		= &m54xx_wdt_fops,
193 };
194 
195 static int __init m54xx_wdt_init(void)
196 {
197 	if (!request_mem_region(MCF_MBAR + MCF_GPT_GCIR0, 4,
198 						"Coldfire M54xx Watchdog")) {
199 		printk(KERN_WARNING
200 				"Coldfire M54xx Watchdog : I/O region busy\n");
201 		return -EBUSY;
202 	}
203 	printk(KERN_INFO "ColdFire watchdog driver is loaded.\n");
204 
205 	return misc_register(&m54xx_wdt_miscdev);
206 }
207 
208 static void __exit m54xx_wdt_exit(void)
209 {
210 	misc_deregister(&m54xx_wdt_miscdev);
211 	release_mem_region(MCF_MBAR + MCF_GPT_GCIR0, 4);
212 }
213 
214 module_init(m54xx_wdt_init);
215 module_exit(m54xx_wdt_exit);
216 
217 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
218 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
219 
220 module_param(heartbeat, int, 0);
221 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
222 
223 module_param(nowayout, int, 0);
224 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
225 
226 MODULE_LICENSE("GPL");
227 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
228