Root/drivers/watchdog/ath79_wdt.c

1/*
2 * Atheros AR71XX/AR724X/AR913X built-in hardware watchdog timer.
3 *
4 * Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
6 *
7 * This driver was based on: drivers/watchdog/ixp4xx_wdt.c
8 * Author: Deepak Saxena <dsaxena@plexity.net>
9 * Copyright 2004 (c) MontaVista, Software, Inc.
10 *
11 * which again was based on sa1100 driver,
12 * Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
13 *
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License version 2 as published
16 * by the Free Software Foundation.
17 *
18 */
19
20#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/bitops.h>
23#include <linux/errno.h>
24#include <linux/fs.h>
25#include <linux/init.h>
26#include <linux/kernel.h>
27#include <linux/miscdevice.h>
28#include <linux/module.h>
29#include <linux/moduleparam.h>
30#include <linux/platform_device.h>
31#include <linux/types.h>
32#include <linux/watchdog.h>
33#include <linux/clk.h>
34#include <linux/err.h>
35
36#include <asm/mach-ath79/ath79.h>
37#include <asm/mach-ath79/ar71xx_regs.h>
38
39#define DRIVER_NAME "ath79-wdt"
40
41#define WDT_TIMEOUT 15 /* seconds */
42
43#define WDOG_CTRL_LAST_RESET BIT(31)
44#define WDOG_CTRL_ACTION_MASK 3
45#define WDOG_CTRL_ACTION_NONE 0 /* no action */
46#define WDOG_CTRL_ACTION_GPI 1 /* general purpose interrupt */
47#define WDOG_CTRL_ACTION_NMI 2 /* NMI */
48#define WDOG_CTRL_ACTION_FCR 3 /* full chip reset */
49
50static bool nowayout = WATCHDOG_NOWAYOUT;
51module_param(nowayout, bool, 0);
52MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
53               "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
54
55static int timeout = WDT_TIMEOUT;
56module_param(timeout, int, 0);
57MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
58              "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
59
60static unsigned long wdt_flags;
61
62#define WDT_FLAGS_BUSY 0
63#define WDT_FLAGS_EXPECT_CLOSE 1
64
65static struct clk *wdt_clk;
66static unsigned long wdt_freq;
67static int boot_status;
68static int max_timeout;
69
70static inline void ath79_wdt_keepalive(void)
71{
72    ath79_reset_wr(AR71XX_RESET_REG_WDOG, wdt_freq * timeout);
73    /* flush write */
74    ath79_reset_rr(AR71XX_RESET_REG_WDOG);
75}
76
77static inline void ath79_wdt_enable(void)
78{
79    ath79_wdt_keepalive();
80    ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
81    /* flush write */
82    ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
83}
84
85static inline void ath79_wdt_disable(void)
86{
87    ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
88    /* flush write */
89    ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
90}
91
92static int ath79_wdt_set_timeout(int val)
93{
94    if (val < 1 || val > max_timeout)
95        return -EINVAL;
96
97    timeout = val;
98    ath79_wdt_keepalive();
99
100    return 0;
101}
102
103static int ath79_wdt_open(struct inode *inode, struct file *file)
104{
105    if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
106        return -EBUSY;
107
108    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
109    ath79_wdt_enable();
110
111    return nonseekable_open(inode, file);
112}
113
114static int ath79_wdt_release(struct inode *inode, struct file *file)
115{
116    if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
117        ath79_wdt_disable();
118    else {
119        pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
120        ath79_wdt_keepalive();
121    }
122
123    clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
124    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
125
126    return 0;
127}
128
129static ssize_t ath79_wdt_write(struct file *file, const char *data,
130                size_t len, loff_t *ppos)
131{
132    if (len) {
133        if (!nowayout) {
134            size_t i;
135
136            clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
137
138            for (i = 0; i != len; i++) {
139                char c;
140
141                if (get_user(c, data + i))
142                    return -EFAULT;
143
144                if (c == 'V')
145                    set_bit(WDT_FLAGS_EXPECT_CLOSE,
146                        &wdt_flags);
147            }
148        }
149
150        ath79_wdt_keepalive();
151    }
152
153    return len;
154}
155
156static const struct watchdog_info ath79_wdt_info = {
157    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
158                  WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
159    .firmware_version = 0,
160    .identity = "ATH79 watchdog",
161};
162
163static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
164                unsigned long arg)
165{
166    void __user *argp = (void __user *)arg;
167    int __user *p = argp;
168    int err;
169    int t;
170
171    switch (cmd) {
172    case WDIOC_GETSUPPORT:
173        err = copy_to_user(argp, &ath79_wdt_info,
174                   sizeof(ath79_wdt_info)) ? -EFAULT : 0;
175        break;
176
177    case WDIOC_GETSTATUS:
178        err = put_user(0, p);
179        break;
180
181    case WDIOC_GETBOOTSTATUS:
182        err = put_user(boot_status, p);
183        break;
184
185    case WDIOC_KEEPALIVE:
186        ath79_wdt_keepalive();
187        err = 0;
188        break;
189
190    case WDIOC_SETTIMEOUT:
191        err = get_user(t, p);
192        if (err)
193            break;
194
195        err = ath79_wdt_set_timeout(t);
196        if (err)
197            break;
198
199        /* fallthrough */
200    case WDIOC_GETTIMEOUT:
201        err = put_user(timeout, p);
202        break;
203
204    default:
205        err = -ENOTTY;
206        break;
207    }
208
209    return err;
210}
211
212static const struct file_operations ath79_wdt_fops = {
213    .owner = THIS_MODULE,
214    .llseek = no_llseek,
215    .write = ath79_wdt_write,
216    .unlocked_ioctl = ath79_wdt_ioctl,
217    .open = ath79_wdt_open,
218    .release = ath79_wdt_release,
219};
220
221static struct miscdevice ath79_wdt_miscdev = {
222    .minor = WATCHDOG_MINOR,
223    .name = "watchdog",
224    .fops = &ath79_wdt_fops,
225};
226
227static int __devinit ath79_wdt_probe(struct platform_device *pdev)
228{
229    u32 ctrl;
230    int err;
231
232    wdt_clk = clk_get(&pdev->dev, "wdt");
233    if (IS_ERR(wdt_clk))
234        return PTR_ERR(wdt_clk);
235
236    err = clk_enable(wdt_clk);
237    if (err)
238        goto err_clk_put;
239
240    wdt_freq = clk_get_rate(wdt_clk);
241    if (!wdt_freq) {
242        err = -EINVAL;
243        goto err_clk_disable;
244    }
245
246    max_timeout = (0xfffffffful / wdt_freq);
247    if (timeout < 1 || timeout > max_timeout) {
248        timeout = max_timeout;
249        dev_info(&pdev->dev,
250            "timeout value must be 0 < timeout < %d, using %d\n",
251            max_timeout, timeout);
252    }
253
254    ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
255    boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
256
257    err = misc_register(&ath79_wdt_miscdev);
258    if (err) {
259        dev_err(&pdev->dev,
260            "unable to register misc device, err=%d\n", err);
261        goto err_clk_disable;
262    }
263
264    return 0;
265
266err_clk_disable:
267    clk_disable(wdt_clk);
268err_clk_put:
269    clk_put(wdt_clk);
270    return err;
271}
272
273static int __devexit ath79_wdt_remove(struct platform_device *pdev)
274{
275    misc_deregister(&ath79_wdt_miscdev);
276    clk_disable(wdt_clk);
277    clk_put(wdt_clk);
278    return 0;
279}
280
281static void ath97_wdt_shutdown(struct platform_device *pdev)
282{
283    ath79_wdt_disable();
284}
285
286static struct platform_driver ath79_wdt_driver = {
287    .remove = __devexit_p(ath79_wdt_remove),
288    .shutdown = ath97_wdt_shutdown,
289    .driver = {
290        .name = DRIVER_NAME,
291        .owner = THIS_MODULE,
292    },
293};
294
295static int __init ath79_wdt_init(void)
296{
297    return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
298}
299module_init(ath79_wdt_init);
300
301static void __exit ath79_wdt_exit(void)
302{
303    platform_driver_unregister(&ath79_wdt_driver);
304}
305module_exit(ath79_wdt_exit);
306
307MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
308MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
309MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
310MODULE_LICENSE("GPL v2");
311MODULE_ALIAS("platform:" DRIVER_NAME);
312MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
313

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