Root/target/linux/ramips/files/drivers/watchdog/ramips_wdt.c

1/*
2 * Ralink RT288X/RT305X built-in hardware watchdog timer
3 *
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5 *
6 * This driver was based on: drivers/watchdog/ixp4xx_wdt.c
7 * Author: Deepak Saxena <dsaxena@plexity.net>
8 * Copyright 2004 (c) MontaVista, Software, Inc.
9 *
10 * which again was based on sa1100 driver,
11 * Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
12 *
13 * parts of the driver are based on Ralink's 2.6.21 BSP
14 *
15 * This program is free software; you can redistribute it and/or modify it
16 * under the terms of the GNU General Public License version 2 as published
17 * by the Free Software Foundation.
18 */
19
20#include <linux/bitops.h>
21#include <linux/errno.h>
22#include <linux/fs.h>
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/miscdevice.h>
26#include <linux/module.h>
27#include <linux/moduleparam.h>
28#include <linux/platform_device.h>
29#include <linux/types.h>
30#include <linux/watchdog.h>
31#include <linux/clk.h>
32#include <linux/err.h>
33
34#define DRIVER_NAME "ramips-wdt"
35
36#define RAMIPS_WDT_TIMEOUT 20 /* seconds */
37#define RAMIPS_WDT_PRESCALE 65536
38
39#define TIMER_REG_TMRSTAT 0x00
40#define TIMER_REG_TMR1LOAD 0x20
41#define TIMER_REG_TMR1CTL 0x28
42
43#define TMRSTAT_TMR1RST BIT(5)
44
45#define TMR1CTL_ENABLE BIT(7)
46#define TMR1CTL_MODE_SHIFT 4
47#define TMR1CTL_MODE_MASK 0x3
48#define TMR1CTL_MODE_FREE_RUNNING 0x0
49#define TMR1CTL_MODE_PERIODIC 0x1
50#define TMR1CTL_MODE_TIMEOUT 0x2
51#define TMR1CTL_MODE_WDT 0x3
52#define TMR1CTL_PRESCALE_MASK 0xf
53#define TMR1CTL_PRESCALE_65536 0xf
54
55static int nowayout = WATCHDOG_NOWAYOUT;
56module_param(nowayout, int, 0);
57MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
58               "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
59
60static int ramips_wdt_timeout = RAMIPS_WDT_TIMEOUT;
61module_param_named(timeout, ramips_wdt_timeout, int, 0);
62MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
63              "(default=" __MODULE_STRING(RAMIPS_WDT_TIMEOUT) "s)");
64
65static unsigned long ramips_wdt_flags;
66
67#define WDT_FLAGS_BUSY 0
68#define WDT_FLAGS_EXPECT_CLOSE 1
69
70static struct clk *ramips_wdt_clk;
71static unsigned long ramips_wdt_freq;
72static int ramips_wdt_max_timeout;
73static void __iomem *ramips_wdt_base;
74
75static inline void ramips_wdt_wr(unsigned reg, u32 val)
76{
77    __raw_writel(val, ramips_wdt_base + reg);
78}
79
80static inline u32 ramips_wdt_rr(unsigned reg)
81{
82    return __raw_readl(ramips_wdt_base + reg);
83}
84
85static inline void ramips_wdt_keepalive(void)
86{
87    ramips_wdt_wr(TIMER_REG_TMR1LOAD, ramips_wdt_timeout * ramips_wdt_freq);
88}
89
90static inline void ramips_wdt_enable(void)
91{
92    u32 t;
93
94    ramips_wdt_keepalive();
95
96    t = ramips_wdt_rr(TIMER_REG_TMR1CTL);
97    t |= TMR1CTL_ENABLE;
98    ramips_wdt_wr(TIMER_REG_TMR1CTL, t);
99}
100
101static inline void ramips_wdt_disable(void)
102{
103    u32 t;
104
105    ramips_wdt_keepalive();
106
107    t = ramips_wdt_rr(TIMER_REG_TMR1CTL);
108    t &= ~TMR1CTL_ENABLE;
109    ramips_wdt_wr(TIMER_REG_TMR1CTL, t);
110}
111
112static int ramips_wdt_set_timeout(int val)
113{
114    if (val < 1 || val > ramips_wdt_max_timeout) {
115        pr_crit(DRIVER_NAME
116            ": timeout value %d must be 0 < timeout < %d\n",
117            val, ramips_wdt_max_timeout);
118        return -EINVAL;
119    }
120
121    ramips_wdt_timeout = val;
122    ramips_wdt_keepalive();
123
124    return 0;
125}
126
127static int ramips_wdt_open(struct inode *inode, struct file *file)
128{
129    u32 t;
130
131    if (test_and_set_bit(WDT_FLAGS_BUSY, &ramips_wdt_flags))
132        return -EBUSY;
133
134    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &ramips_wdt_flags);
135
136    t = ramips_wdt_rr(TIMER_REG_TMR1CTL);
137    t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
138           TMR1CTL_PRESCALE_MASK);
139    t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
140          TMR1CTL_PRESCALE_65536);
141    ramips_wdt_wr(TIMER_REG_TMR1CTL, t);
142
143    ramips_wdt_enable();
144
145    return nonseekable_open(inode, file);
146}
147
148static int ramips_wdt_release(struct inode *inode, struct file *file)
149{
150    if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &ramips_wdt_flags))
151        ramips_wdt_disable();
152    else {
153        pr_crit(DRIVER_NAME ": device closed unexpectedly, "
154            "watchdog timer will not stop!\n");
155        ramips_wdt_keepalive();
156    }
157
158    clear_bit(WDT_FLAGS_BUSY, &ramips_wdt_flags);
159    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &ramips_wdt_flags);
160
161    return 0;
162}
163
164static ssize_t ramips_wdt_write(struct file *file, const char *data,
165                size_t len, loff_t *ppos)
166{
167    if (len) {
168        if (!nowayout) {
169            size_t i;
170
171            clear_bit(WDT_FLAGS_EXPECT_CLOSE, &ramips_wdt_flags);
172
173            for (i = 0; i != len; i++) {
174                char c;
175
176                if (get_user(c, data + i))
177                    return -EFAULT;
178
179                if (c == 'V')
180                    set_bit(WDT_FLAGS_EXPECT_CLOSE,
181                        &ramips_wdt_flags);
182            }
183        }
184
185        ramips_wdt_keepalive();
186    }
187
188    return len;
189}
190
191static const struct watchdog_info ramips_wdt_info = {
192    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
193                  WDIOF_MAGICCLOSE,
194    .firmware_version = 0,
195    .identity = "RAMIPS watchdog",
196};
197
198static long ramips_wdt_ioctl(struct file *file, unsigned int cmd,
199                unsigned long arg)
200{
201    void __user *argp = (void __user *)arg;
202    int __user *p = argp;
203    int err;
204    int t;
205
206    switch (cmd) {
207    case WDIOC_GETSUPPORT:
208        err = copy_to_user(argp, &ramips_wdt_info,
209                   sizeof(ramips_wdt_info)) ? -EFAULT : 0;
210        break;
211
212    case WDIOC_GETSTATUS:
213        err = put_user(0, p);
214        break;
215
216    case WDIOC_KEEPALIVE:
217        ramips_wdt_keepalive();
218        err = 0;
219        break;
220
221    case WDIOC_SETTIMEOUT:
222        err = get_user(t, p);
223        if (err)
224            break;
225
226        err = ramips_wdt_set_timeout(t);
227        if (err)
228            break;
229
230        /* fallthrough */
231    case WDIOC_GETTIMEOUT:
232        err = put_user(ramips_wdt_timeout, p);
233        break;
234
235    default:
236        err = -ENOTTY;
237        break;
238    }
239
240    return err;
241}
242
243static const struct file_operations ramips_wdt_fops = {
244    .owner = THIS_MODULE,
245    .llseek = no_llseek,
246    .write = ramips_wdt_write,
247    .unlocked_ioctl = ramips_wdt_ioctl,
248    .open = ramips_wdt_open,
249    .release = ramips_wdt_release,
250};
251
252static struct miscdevice ramips_wdt_miscdev = {
253    .minor = WATCHDOG_MINOR,
254    .name = "watchdog",
255    .fops = &ramips_wdt_fops,
256};
257
258static int __devinit ramips_wdt_probe(struct platform_device *pdev)
259{
260    struct resource *res;
261    int err;
262
263    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
264    if (!res) {
265        dev_err(&pdev->dev, "no memory resource found\n");
266        return -EINVAL;
267    }
268
269    ramips_wdt_base = ioremap(res->start, resource_size(res));
270    if (!ramips_wdt_base)
271        return -ENOMEM;
272
273    ramips_wdt_clk = clk_get(&pdev->dev, "wdt");
274    if (IS_ERR(ramips_wdt_clk)) {
275        err = PTR_ERR(ramips_wdt_clk);
276        goto err_unmap;
277    }
278
279    err = clk_enable(ramips_wdt_clk);
280    if (err)
281        goto err_clk_put;
282
283    ramips_wdt_freq = clk_get_rate(ramips_wdt_clk) / RAMIPS_WDT_PRESCALE;
284    if (!ramips_wdt_freq) {
285        err = -EINVAL;
286        goto err_clk_disable;
287    }
288
289    ramips_wdt_max_timeout = (0xfffful / ramips_wdt_freq);
290    if (ramips_wdt_timeout < 1 ||
291        ramips_wdt_timeout > ramips_wdt_max_timeout) {
292        ramips_wdt_timeout = ramips_wdt_max_timeout;
293        dev_info(&pdev->dev,
294            "timeout value must be 0 < timeout < %d, using %d\n",
295            ramips_wdt_max_timeout, ramips_wdt_timeout);
296    }
297
298    err = misc_register(&ramips_wdt_miscdev);
299    if (err) {
300        dev_err(&pdev->dev,
301            "unable to register misc device, err=%d\n", err);
302        goto err_clk_disable;
303    }
304
305    return 0;
306
307err_clk_disable:
308    clk_disable(ramips_wdt_clk);
309err_clk_put:
310    clk_put(ramips_wdt_clk);
311err_unmap:
312    iounmap(ramips_wdt_base);
313    return err;
314}
315
316static int __devexit ramips_wdt_remove(struct platform_device *pdev)
317{
318    misc_deregister(&ramips_wdt_miscdev);
319    clk_disable(ramips_wdt_clk);
320    clk_put(ramips_wdt_clk);
321    iounmap(ramips_wdt_base);
322    return 0;
323}
324
325static void ramips_wdt_shutdown(struct platform_device *pdev)
326{
327    ramips_wdt_disable();
328}
329
330static struct platform_driver ramips_wdt_driver = {
331    .remove = __devexit_p(ramips_wdt_remove),
332    .shutdown = ramips_wdt_shutdown,
333    .driver = {
334        .name = DRIVER_NAME,
335        .owner = THIS_MODULE,
336    },
337};
338
339static int __init ramips_wdt_init(void)
340{
341    return platform_driver_probe(&ramips_wdt_driver, ramips_wdt_probe);
342}
343module_init(ramips_wdt_init);
344
345static void __exit ramips_wdt_exit(void)
346{
347    platform_driver_unregister(&ramips_wdt_driver);
348}
349module_exit(ramips_wdt_exit);
350
351MODULE_DESCRIPTION("Ralink RT288X/RT305X hardware watchdog driver");
352MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
353MODULE_LICENSE("GPL v2");
354MODULE_ALIAS("platform:" DRIVER_NAME);
355MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
356

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