[WATCHDOG] at32ap700x_wdt.c - Add spinlock support
[deliverable/linux.git] / drivers / char / watchdog / at32ap700x_wdt.c
CommitLineData
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1/*
2 * Watchdog driver for Atmel AT32AP700X devices
3 *
4 * Copyright (C) 2005-2006 Atmel Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/miscdevice.h>
16#include <linux/fs.h>
17#include <linux/platform_device.h>
18#include <linux/watchdog.h>
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19#include <linux/uaccess.h>
20#include <linux/io.h>
e75e6577 21#include <linux/spinlock.h>
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22
23#define TIMEOUT_MIN 1
a9cb3959 24#define TIMEOUT_MAX 2
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25#define TIMEOUT_DEFAULT TIMEOUT_MAX
26
27/* module parameters */
28static int timeout = TIMEOUT_DEFAULT;
29module_param(timeout, int, 0);
30MODULE_PARM_DESC(timeout,
31 "Timeout value. Limited to be 1 or 2 seconds. (default="
32 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
a9cb3959 33
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34static int nowayout = WATCHDOG_NOWAYOUT;
35module_param(nowayout, int, 0);
36MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
37 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
38
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39/* Watchdog registers and write/read macro */
40#define WDT_CTRL 0x00
41#define WDT_CTRL_EN 0
42#define WDT_CTRL_PSEL 8
43#define WDT_CTRL_KEY 24
44
45#define WDT_CLR 0x04
46
47#define WDT_BIT(name) (1 << WDT_##name)
c0ead7e0 48#define WDT_BF(name, value) ((value) << WDT_##name)
a9cb3959 49
c0ead7e0 50#define wdt_readl(dev, reg) \
a9cb3959 51 __raw_readl((dev)->regs + WDT_##reg)
c0ead7e0 52#define wdt_writel(dev, reg, value) \
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53 __raw_writel((value), (dev)->regs + WDT_##reg)
54
55struct wdt_at32ap700x {
56 void __iomem *regs;
e75e6577 57 spinlock_t io_lock;
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58 int timeout;
59 int users;
60 struct miscdevice miscdev;
61};
62
63static struct wdt_at32ap700x *wdt;
28401140 64static char expect_release;
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65
66/*
67 * Disable the watchdog.
68 */
c0ead7e0 69static inline void at32_wdt_stop(void)
a9cb3959 70{
e75e6577 71 spin_lock(&wdt->io_lock);
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72 unsigned long psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
73 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
74 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
e75e6577 75 spin_unlock(&wdt->io_lock);
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76}
77
78/*
79 * Enable and reset the watchdog.
80 */
c0ead7e0 81static inline void at32_wdt_start(void)
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82{
83 /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
84 unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
85
e75e6577 86 spin_lock(&wdt->io_lock);
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87 wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
88 | WDT_BF(CTRL_PSEL, psel)
89 | WDT_BF(CTRL_KEY, 0x55));
90 wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
91 | WDT_BF(CTRL_PSEL, psel)
92 | WDT_BF(CTRL_KEY, 0xaa));
e75e6577 93 spin_unlock(&wdt->io_lock);
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94}
95
96/*
97 * Pat the watchdog timer.
98 */
c0ead7e0 99static inline void at32_wdt_pat(void)
a9cb3959 100{
e75e6577 101 spin_lock(&wdt->io_lock);
a9cb3959 102 wdt_writel(wdt, CLR, 0x42);
e75e6577 103 spin_unlock(&wdt->io_lock);
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104}
105
106/*
107 * Watchdog device is opened, and watchdog starts running.
108 */
109static int at32_wdt_open(struct inode *inode, struct file *file)
110{
111 if (test_and_set_bit(1, &wdt->users))
112 return -EBUSY;
113
114 at32_wdt_start();
115 return nonseekable_open(inode, file);
116}
117
118/*
28401140 119 * Close the watchdog device.
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120 */
121static int at32_wdt_close(struct inode *inode, struct file *file)
122{
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123 if (expect_release == 42) {
124 at32_wdt_stop();
125 } else {
126 dev_dbg(wdt->miscdev.parent,
127 "Unexpected close, not stopping watchdog!\n");
128 at32_wdt_pat();
129 }
a9cb3959 130 clear_bit(1, &wdt->users);
28401140 131 expect_release = 0;
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132 return 0;
133}
134
135/*
136 * Change the watchdog time interval.
137 */
138static int at32_wdt_settimeout(int time)
139{
140 /*
141 * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
142 * 2 ^ 16 allowing up to 2 seconds timeout.
143 */
144 if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
145 return -EINVAL;
146
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147 /*
148 * Set new watchdog time. It will be used when at32_wdt_start() is
149 * called.
150 */
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151 wdt->timeout = time;
152 return 0;
153}
154
155static struct watchdog_info at32_wdt_info = {
156 .identity = "at32ap700x watchdog",
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157 .options = WDIOF_SETTIMEOUT |
158 WDIOF_KEEPALIVEPING |
159 WDIOF_MAGICCLOSE,
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160};
161
162/*
163 * Handle commands from user-space.
164 */
165static int at32_wdt_ioctl(struct inode *inode, struct file *file,
166 unsigned int cmd, unsigned long arg)
167{
168 int ret = -ENOTTY;
169 int time;
170 void __user *argp = (void __user *)arg;
171 int __user *p = argp;
172
c37f2713 173 switch (cmd) {
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174 case WDIOC_KEEPALIVE:
175 at32_wdt_pat();
176 ret = 0;
177 break;
178 case WDIOC_GETSUPPORT:
179 ret = copy_to_user(argp, &at32_wdt_info,
180 sizeof(at32_wdt_info)) ? -EFAULT : 0;
181 break;
182 case WDIOC_SETTIMEOUT:
183 ret = get_user(time, p);
184 if (ret)
185 break;
186 ret = at32_wdt_settimeout(time);
187 if (ret)
188 break;
189 /* Enable new time value */
190 at32_wdt_start();
191 /* fall through */
192 case WDIOC_GETTIMEOUT:
193 ret = put_user(wdt->timeout, p);
194 break;
195 case WDIOC_GETSTATUS: /* fall through */
196 case WDIOC_GETBOOTSTATUS:
197 ret = put_user(0, p);
198 break;
199 case WDIOC_SETOPTIONS:
200 ret = get_user(time, p);
201 if (ret)
202 break;
203 if (time & WDIOS_DISABLECARD)
204 at32_wdt_stop();
205 if (time & WDIOS_ENABLECARD)
206 at32_wdt_start();
207 ret = 0;
208 break;
209 }
210
211 return ret;
212}
213
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214static ssize_t at32_wdt_write(struct file *file, const char __user *data,
215 size_t len, loff_t *ppos)
a9cb3959 216{
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217 /* See if we got the magic character 'V' and reload the timer */
218 if (len) {
219 if (!nowayout) {
220 size_t i;
221
222 /*
223 * note: just in case someone wrote the magic
224 * character five months ago...
225 */
226 expect_release = 0;
227
228 /*
229 * scan to see whether or not we got the magic
230 * character
231 */
232 for (i = 0; i != len; i++) {
233 char c;
234 if (get_user(c, data+i))
235 return -EFAULT;
236 if (c == 'V')
237 expect_release = 42;
238 }
239 }
240 /* someone wrote to us, we should pat the watchdog */
241 at32_wdt_pat();
242 }
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243 return len;
244}
245
246static const struct file_operations at32_wdt_fops = {
247 .owner = THIS_MODULE,
248 .llseek = no_llseek,
249 .ioctl = at32_wdt_ioctl,
250 .open = at32_wdt_open,
251 .release = at32_wdt_close,
252 .write = at32_wdt_write,
253};
254
255static int __init at32_wdt_probe(struct platform_device *pdev)
256{
257 struct resource *regs;
258 int ret;
259
260 if (wdt) {
261 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
262 return -EBUSY;
263 }
264
265 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
266 if (!regs) {
267 dev_dbg(&pdev->dev, "missing mmio resource\n");
268 return -ENXIO;
269 }
270
271 wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
272 if (!wdt) {
273 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
274 return -ENOMEM;
275 }
276
277 wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
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278 if (!wdt->regs) {
279 ret = -ENOMEM;
280 dev_dbg(&pdev->dev, "could not map I/O memory\n");
281 goto err_free;
282 }
e75e6577 283 spin_lock_init(&wdt->io_lock);
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284 wdt->users = 0;
285 wdt->miscdev.minor = WATCHDOG_MINOR;
286 wdt->miscdev.name = "watchdog";
287 wdt->miscdev.fops = &at32_wdt_fops;
288
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289 if (at32_wdt_settimeout(timeout)) {
290 at32_wdt_settimeout(TIMEOUT_DEFAULT);
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291 dev_dbg(&pdev->dev,
292 "default timeout invalid, set to %d sec.\n",
726c9f61 293 TIMEOUT_DEFAULT);
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294 }
295
296 ret = misc_register(&wdt->miscdev);
297 if (ret) {
298 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
47d17763 299 goto err_iounmap;
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300 }
301
302 platform_set_drvdata(pdev, wdt);
303 wdt->miscdev.parent = &pdev->dev;
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304 dev_info(&pdev->dev,
305 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
306 wdt->regs, wdt->timeout, nowayout);
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307
308 return 0;
309
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310err_iounmap:
311 iounmap(wdt->regs);
312err_free:
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313 kfree(wdt);
314 wdt = NULL;
315 return ret;
316}
317
318static int __exit at32_wdt_remove(struct platform_device *pdev)
319{
320 if (wdt && platform_get_drvdata(pdev) == wdt) {
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321 /* Stop the timer before we leave */
322 if (!nowayout)
323 at32_wdt_stop();
324
a9cb3959 325 misc_deregister(&wdt->miscdev);
ff732316 326 iounmap(wdt->regs);
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327 kfree(wdt);
328 wdt = NULL;
329 platform_set_drvdata(pdev, NULL);
330 }
331
332 return 0;
333}
334
335static void at32_wdt_shutdown(struct platform_device *pdev)
336{
337 at32_wdt_stop();
338}
339
340#ifdef CONFIG_PM
341static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
342{
343 at32_wdt_stop();
344 return 0;
345}
346
347static int at32_wdt_resume(struct platform_device *pdev)
348{
349 if (wdt->users)
350 at32_wdt_start();
351 return 0;
352}
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353#else
354#define at32_wdt_suspend NULL
355#define at32_wdt_resume NULL
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356#endif
357
358static struct platform_driver at32_wdt_driver = {
359 .remove = __exit_p(at32_wdt_remove),
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360 .suspend = at32_wdt_suspend,
361 .resume = at32_wdt_resume,
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362 .driver = {
363 .name = "at32_wdt",
364 .owner = THIS_MODULE,
365 },
366 .shutdown = at32_wdt_shutdown,
367};
368
369static int __init at32_wdt_init(void)
370{
371 return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
372}
373module_init(at32_wdt_init);
374
375static void __exit at32_wdt_exit(void)
376{
377 platform_driver_unregister(&at32_wdt_driver);
378}
379module_exit(at32_wdt_exit);
380
381MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
382MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
383MODULE_LICENSE("GPL");
384MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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