Root/drivers/watchdog/mtx-1_wdt.c

1/*
2 * Driver for the MTX-1 Watchdog.
3 *
4 * (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
5 * All Rights Reserved.
6 * http://www.4g-systems.biz
7 *
8 * (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * Neither Michael Stickel nor 4G Systems admit liability nor provide
16 * warranty for any of this software. This material is provided
17 * "AS-IS" and at no charge.
18 *
19 * (c) Copyright 2005 4G Systems <info@4g-systems.biz>
20 *
21 * Release 0.01.
22 * Author: Michael Stickel michael.stickel@4g-systems.biz
23 *
24 * Release 0.02.
25 * Author: Florian Fainelli florian@openwrt.org
26 * use the Linux watchdog/timer APIs
27 *
28 * The Watchdog is configured to reset the MTX-1
29 * if it is not triggered for 100 seconds.
30 * It should not be triggered more often than 1.6 seconds.
31 *
32 * A timer triggers the watchdog every 5 seconds, until
33 * it is opened for the first time. After the first open
34 * it MUST be triggered every 2..95 seconds.
35 */
36
37#include <linux/module.h>
38#include <linux/moduleparam.h>
39#include <linux/types.h>
40#include <linux/errno.h>
41#include <linux/miscdevice.h>
42#include <linux/fs.h>
43#include <linux/init.h>
44#include <linux/ioport.h>
45#include <linux/timer.h>
46#include <linux/completion.h>
47#include <linux/jiffies.h>
48#include <linux/watchdog.h>
49#include <linux/platform_device.h>
50#include <linux/io.h>
51#include <linux/uaccess.h>
52#include <linux/gpio.h>
53
54#include <asm/mach-au1x00/au1000.h>
55
56#define MTX1_WDT_INTERVAL (5 * HZ)
57
58static int ticks = 100 * HZ;
59
60static struct {
61    struct completion stop;
62    spinlock_t lock;
63    int running;
64    struct timer_list timer;
65    int queue;
66    int default_ticks;
67    unsigned long inuse;
68    unsigned gpio;
69    unsigned int gstate;
70} mtx1_wdt_device;
71
72static void mtx1_wdt_trigger(unsigned long unused)
73{
74    spin_lock(&mtx1_wdt_device.lock);
75    if (mtx1_wdt_device.running)
76        ticks--;
77
78    /* toggle wdt gpio */
79    mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
80    gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
81
82    if (mtx1_wdt_device.queue && ticks)
83        mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
84    else
85        complete(&mtx1_wdt_device.stop);
86    spin_unlock(&mtx1_wdt_device.lock);
87}
88
89static void mtx1_wdt_reset(void)
90{
91    ticks = mtx1_wdt_device.default_ticks;
92}
93
94
95static void mtx1_wdt_start(void)
96{
97    unsigned long flags;
98
99    spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
100    if (!mtx1_wdt_device.queue) {
101        mtx1_wdt_device.queue = 1;
102        mtx1_wdt_device.gstate = 1;
103        gpio_set_value(mtx1_wdt_device.gpio, 1);
104        mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
105    }
106    mtx1_wdt_device.running++;
107    spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
108}
109
110static int mtx1_wdt_stop(void)
111{
112    unsigned long flags;
113
114    spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
115    if (mtx1_wdt_device.queue) {
116        mtx1_wdt_device.queue = 0;
117        mtx1_wdt_device.gstate = 0;
118        gpio_set_value(mtx1_wdt_device.gpio, 0);
119    }
120    ticks = mtx1_wdt_device.default_ticks;
121    spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
122    return 0;
123}
124
125/* Filesystem functions */
126
127static int mtx1_wdt_open(struct inode *inode, struct file *file)
128{
129    if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
130        return -EBUSY;
131    return nonseekable_open(inode, file);
132}
133
134
135static int mtx1_wdt_release(struct inode *inode, struct file *file)
136{
137    clear_bit(0, &mtx1_wdt_device.inuse);
138    return 0;
139}
140
141static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
142                            unsigned long arg)
143{
144    void __user *argp = (void __user *)arg;
145    int __user *p = (int __user *)argp;
146    unsigned int value;
147    static const struct watchdog_info ident = {
148        .options = WDIOF_CARDRESET,
149        .identity = "MTX-1 WDT",
150    };
151
152    switch (cmd) {
153    case WDIOC_GETSUPPORT:
154        if (copy_to_user(argp, &ident, sizeof(ident)))
155            return -EFAULT;
156        break;
157    case WDIOC_GETSTATUS:
158    case WDIOC_GETBOOTSTATUS:
159        put_user(0, p);
160        break;
161    case WDIOC_SETOPTIONS:
162        if (get_user(value, p))
163            return -EFAULT;
164        if (value & WDIOS_ENABLECARD)
165            mtx1_wdt_start();
166        else if (value & WDIOS_DISABLECARD)
167            mtx1_wdt_stop();
168        else
169            return -EINVAL;
170        return 0;
171    case WDIOC_KEEPALIVE:
172        mtx1_wdt_reset();
173        break;
174    default:
175        return -ENOTTY;
176    }
177    return 0;
178}
179
180
181static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
182                        size_t count, loff_t *ppos)
183{
184    if (!count)
185        return -EIO;
186    mtx1_wdt_reset();
187    return count;
188}
189
190static const struct file_operations mtx1_wdt_fops = {
191    .owner = THIS_MODULE,
192    .llseek = no_llseek,
193    .unlocked_ioctl = mtx1_wdt_ioctl,
194    .open = mtx1_wdt_open,
195    .write = mtx1_wdt_write,
196    .release = mtx1_wdt_release,
197};
198
199
200static struct miscdevice mtx1_wdt_misc = {
201    .minor = WATCHDOG_MINOR,
202    .name = "watchdog",
203    .fops = &mtx1_wdt_fops,
204};
205
206
207static int __devinit mtx1_wdt_probe(struct platform_device *pdev)
208{
209    int ret;
210
211    mtx1_wdt_device.gpio = pdev->resource[0].start;
212    ret = gpio_request_one(mtx1_wdt_device.gpio,
213                GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
214    if (ret < 0) {
215        dev_err(&pdev->dev, "failed to request gpio");
216        return ret;
217    }
218
219    spin_lock_init(&mtx1_wdt_device.lock);
220    init_completion(&mtx1_wdt_device.stop);
221    mtx1_wdt_device.queue = 0;
222    clear_bit(0, &mtx1_wdt_device.inuse);
223    setup_timer(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0L);
224    mtx1_wdt_device.default_ticks = ticks;
225
226    ret = misc_register(&mtx1_wdt_misc);
227    if (ret < 0) {
228        dev_err(&pdev->dev, "failed to register\n");
229        return ret;
230    }
231    mtx1_wdt_start();
232    dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
233    return 0;
234}
235
236static int __devexit mtx1_wdt_remove(struct platform_device *pdev)
237{
238    /* FIXME: do we need to lock this test ? */
239    if (mtx1_wdt_device.queue) {
240        mtx1_wdt_device.queue = 0;
241        wait_for_completion(&mtx1_wdt_device.stop);
242    }
243
244    gpio_free(mtx1_wdt_device.gpio);
245    misc_deregister(&mtx1_wdt_misc);
246    return 0;
247}
248
249static struct platform_driver mtx1_wdt_driver = {
250    .probe = mtx1_wdt_probe,
251    .remove = __devexit_p(mtx1_wdt_remove),
252    .driver.name = "mtx1-wdt",
253    .driver.owner = THIS_MODULE,
254};
255
256module_platform_driver(mtx1_wdt_driver);
257
258MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
259MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
260MODULE_LICENSE("GPL");
261MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
262MODULE_ALIAS("platform:mtx1-wdt");
263

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