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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/module.h>
22 #include <linux/moduleparam.h>
23 #include <linux/types.h>
24 #include <linux/kernel.h>
25 #include <linux/fs.h>
26 #include <linux/miscdevice.h>
27 #include <linux/watchdog.h>
28 #include <linux/init.h>
29 #include <linux/bitops.h>
30 #include <linux/ioport.h>
31 #include <linux/uaccess.h>
32
33 #include <asm/coldfire.h>
34 #include <asm/m54xxsim.h>
35 #include <asm/m54xxgpt.h>
36
37 static bool nowayout = WATCHDOG_NOWAYOUT;
38 static unsigned int heartbeat = 30; /* (secs) Default is 0.5 minute */
39 static unsigned long wdt_status;
40
41 #define WDT_IN_USE 0
42 #define WDT_OK_TO_CLOSE 1
43
wdt_enable(void)44 static void wdt_enable(void)
45 {
46 unsigned int gms0;
47
48 /* preserve GPIO usage, if any */
49 gms0 = __raw_readl(MCF_GPT_GMS0);
50 if (gms0 & MCF_GPT_GMS_TMS_GPIO)
51 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
52 | MCF_GPT_GMS_OD);
53 else
54 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
55 __raw_writel(gms0, MCF_GPT_GMS0);
56 __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
57 MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
58 gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
59 __raw_writel(gms0, MCF_GPT_GMS0);
60 }
61
wdt_disable(void)62 static void wdt_disable(void)
63 {
64 unsigned int gms0;
65
66 /* disable watchdog */
67 gms0 = __raw_readl(MCF_GPT_GMS0);
68 gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
69 __raw_writel(gms0, MCF_GPT_GMS0);
70 }
71
wdt_keepalive(void)72 static void wdt_keepalive(void)
73 {
74 unsigned int gms0;
75
76 gms0 = __raw_readl(MCF_GPT_GMS0);
77 gms0 |= MCF_GPT_GMS_OCPW(0xA5);
78 __raw_writel(gms0, MCF_GPT_GMS0);
79 }
80
m54xx_wdt_open(struct inode * inode,struct file * file)81 static int m54xx_wdt_open(struct inode *inode, struct file *file)
82 {
83 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
84 return -EBUSY;
85
86 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
87 wdt_enable();
88 return stream_open(inode, file);
89 }
90
m54xx_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)91 static ssize_t m54xx_wdt_write(struct file *file, const char *data,
92 size_t len, loff_t *ppos)
93 {
94 if (len) {
95 if (!nowayout) {
96 size_t i;
97
98 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
99
100 for (i = 0; i != len; i++) {
101 char c;
102
103 if (get_user(c, data + i))
104 return -EFAULT;
105 if (c == 'V')
106 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
107 }
108 }
109 wdt_keepalive();
110 }
111 return len;
112 }
113
114 static const struct watchdog_info ident = {
115 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
116 WDIOF_KEEPALIVEPING,
117 .identity = "Coldfire M54xx Watchdog",
118 };
119
m54xx_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)120 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
121 unsigned long arg)
122 {
123 int ret = -ENOTTY;
124 int time;
125
126 switch (cmd) {
127 case WDIOC_GETSUPPORT:
128 ret = copy_to_user((struct watchdog_info *)arg, &ident,
129 sizeof(ident)) ? -EFAULT : 0;
130 break;
131
132 case WDIOC_GETSTATUS:
133 ret = put_user(0, (int *)arg);
134 break;
135
136 case WDIOC_GETBOOTSTATUS:
137 ret = put_user(0, (int *)arg);
138 break;
139
140 case WDIOC_KEEPALIVE:
141 wdt_keepalive();
142 ret = 0;
143 break;
144
145 case WDIOC_SETTIMEOUT:
146 ret = get_user(time, (int *)arg);
147 if (ret)
148 break;
149
150 if (time <= 0 || time > 30) {
151 ret = -EINVAL;
152 break;
153 }
154
155 heartbeat = time;
156 wdt_enable();
157 /* Fall through */
158
159 case WDIOC_GETTIMEOUT:
160 ret = put_user(heartbeat, (int *)arg);
161 break;
162 }
163 return ret;
164 }
165
m54xx_wdt_release(struct inode * inode,struct file * file)166 static int m54xx_wdt_release(struct inode *inode, struct file *file)
167 {
168 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
169 wdt_disable();
170 else {
171 pr_crit("Device closed unexpectedly - timer will not stop\n");
172 wdt_keepalive();
173 }
174 clear_bit(WDT_IN_USE, &wdt_status);
175 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
176
177 return 0;
178 }
179
180
181 static const struct file_operations m54xx_wdt_fops = {
182 .owner = THIS_MODULE,
183 .llseek = no_llseek,
184 .write = m54xx_wdt_write,
185 .unlocked_ioctl = m54xx_wdt_ioctl,
186 .open = m54xx_wdt_open,
187 .release = m54xx_wdt_release,
188 };
189
190 static struct miscdevice m54xx_wdt_miscdev = {
191 .minor = WATCHDOG_MINOR,
192 .name = "watchdog",
193 .fops = &m54xx_wdt_fops,
194 };
195
m54xx_wdt_init(void)196 static int __init m54xx_wdt_init(void)
197 {
198 if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) {
199 pr_warn("I/O region busy\n");
200 return -EBUSY;
201 }
202 pr_info("driver is loaded\n");
203
204 return misc_register(&m54xx_wdt_miscdev);
205 }
206
m54xx_wdt_exit(void)207 static void __exit m54xx_wdt_exit(void)
208 {
209 misc_deregister(&m54xx_wdt_miscdev);
210 release_mem_region(MCF_GPT_GCIR0, 4);
211 }
212
213 module_init(m54xx_wdt_init);
214 module_exit(m54xx_wdt_exit);
215
216 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
217 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
218
219 module_param(heartbeat, int, 0);
220 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
221
222 module_param(nowayout, bool, 0);
223 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
224
225 MODULE_LICENSE("GPL");
226