watchdog: nowayout is bool
[linux-2.6.git] / drivers / watchdog / m54xx_wdt.c
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
44 static void wdt_enable(void)
45 {
46         unsigned int gms0;
47
48         /* preserve GPIO usage, if any */
49         gms0 = __raw_readl(MCF_MBAR + 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_MBAR + MCF_GPT_GMS0);
56         __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
57                         MCF_GPT_GCIR_CNT(0xffff), MCF_MBAR + MCF_GPT_GCIR0);
58         gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
59         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
60 }
61
62 static void wdt_disable(void)
63 {
64         unsigned int gms0;
65
66         /* disable watchdog */
67         gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
68         gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
69         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
70 }
71
72 static void wdt_keepalive(void)
73 {
74         unsigned int gms0;
75
76         gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
77         gms0 |= MCF_GPT_GMS_OCPW(0xA5);
78         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
79 }
80
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 nonseekable_open(inode, file);
89 }
90
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
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
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
196 static int __init m54xx_wdt_init(void)
197 {
198         if (!request_mem_region(MCF_MBAR + MCF_GPT_GCIR0, 4,
199                                                 "Coldfire M54xx Watchdog")) {
200                 pr_warn("I/O region busy\n");
201                 return -EBUSY;
202         }
203         pr_info("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, bool, 0);
224 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
225
226 MODULE_LICENSE("GPL");
227 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);