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Linux/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/io.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 #include <linux/of.h>
 36 #include <linux/of_platform.h>
 37 
 38 #define DRIVER_NAME     "ath79-wdt"
 39 
 40 #define WDT_TIMEOUT     15      /* seconds */
 41 
 42 #define WDOG_REG_CTRL           0x00
 43 #define WDOG_REG_TIMER          0x04
 44 
 45 #define WDOG_CTRL_LAST_RESET    BIT(31)
 46 #define WDOG_CTRL_ACTION_MASK   3
 47 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
 48 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
 49 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
 50 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
 51 
 52 static bool nowayout = WATCHDOG_NOWAYOUT;
 53 module_param(nowayout, bool, 0);
 54 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
 55                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 56 
 57 static int timeout = WDT_TIMEOUT;
 58 module_param(timeout, int, 0);
 59 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
 60                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
 61 
 62 static unsigned long wdt_flags;
 63 
 64 #define WDT_FLAGS_BUSY          0
 65 #define WDT_FLAGS_EXPECT_CLOSE  1
 66 
 67 static struct clk *wdt_clk;
 68 static unsigned long wdt_freq;
 69 static int boot_status;
 70 static int max_timeout;
 71 static void __iomem *wdt_base;
 72 
 73 static inline void ath79_wdt_wr(unsigned reg, u32 val)
 74 {
 75         iowrite32(val, wdt_base + reg);
 76 }
 77 
 78 static inline u32 ath79_wdt_rr(unsigned reg)
 79 {
 80         return ioread32(wdt_base + reg);
 81 }
 82 
 83 static inline void ath79_wdt_keepalive(void)
 84 {
 85         ath79_wdt_wr(WDOG_REG_TIMER, wdt_freq * timeout);
 86         /* flush write */
 87         ath79_wdt_rr(WDOG_REG_TIMER);
 88 }
 89 
 90 static inline void ath79_wdt_enable(void)
 91 {
 92         ath79_wdt_keepalive();
 93         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_FCR);
 94         /* flush write */
 95         ath79_wdt_rr(WDOG_REG_CTRL);
 96 }
 97 
 98 static inline void ath79_wdt_disable(void)
 99 {
100         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_NONE);
101         /* flush write */
102         ath79_wdt_rr(WDOG_REG_CTRL);
103 }
104 
105 static int ath79_wdt_set_timeout(int val)
106 {
107         if (val < 1 || val > max_timeout)
108                 return -EINVAL;
109 
110         timeout = val;
111         ath79_wdt_keepalive();
112 
113         return 0;
114 }
115 
116 static int ath79_wdt_open(struct inode *inode, struct file *file)
117 {
118         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
119                 return -EBUSY;
120 
121         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
122         ath79_wdt_enable();
123 
124         return nonseekable_open(inode, file);
125 }
126 
127 static int ath79_wdt_release(struct inode *inode, struct file *file)
128 {
129         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
130                 ath79_wdt_disable();
131         else {
132                 pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
133                 ath79_wdt_keepalive();
134         }
135 
136         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
137         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
138 
139         return 0;
140 }
141 
142 static ssize_t ath79_wdt_write(struct file *file, const char *data,
143                                 size_t len, loff_t *ppos)
144 {
145         if (len) {
146                 if (!nowayout) {
147                         size_t i;
148 
149                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
150 
151                         for (i = 0; i != len; i++) {
152                                 char c;
153 
154                                 if (get_user(c, data + i))
155                                         return -EFAULT;
156 
157                                 if (c == 'V')
158                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
159                                                 &wdt_flags);
160                         }
161                 }
162 
163                 ath79_wdt_keepalive();
164         }
165 
166         return len;
167 }
168 
169 static const struct watchdog_info ath79_wdt_info = {
170         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
171                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
172         .firmware_version       = 0,
173         .identity               = "ATH79 watchdog",
174 };
175 
176 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
177                             unsigned long arg)
178 {
179         void __user *argp = (void __user *)arg;
180         int __user *p = argp;
181         int err;
182         int t;
183 
184         switch (cmd) {
185         case WDIOC_GETSUPPORT:
186                 err = copy_to_user(argp, &ath79_wdt_info,
187                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
188                 break;
189 
190         case WDIOC_GETSTATUS:
191                 err = put_user(0, p);
192                 break;
193 
194         case WDIOC_GETBOOTSTATUS:
195                 err = put_user(boot_status, p);
196                 break;
197 
198         case WDIOC_KEEPALIVE:
199                 ath79_wdt_keepalive();
200                 err = 0;
201                 break;
202 
203         case WDIOC_SETTIMEOUT:
204                 err = get_user(t, p);
205                 if (err)
206                         break;
207 
208                 err = ath79_wdt_set_timeout(t);
209                 if (err)
210                         break;
211 
212                 /* fallthrough */
213         case WDIOC_GETTIMEOUT:
214                 err = put_user(timeout, p);
215                 break;
216 
217         default:
218                 err = -ENOTTY;
219                 break;
220         }
221 
222         return err;
223 }
224 
225 static const struct file_operations ath79_wdt_fops = {
226         .owner          = THIS_MODULE,
227         .llseek         = no_llseek,
228         .write          = ath79_wdt_write,
229         .unlocked_ioctl = ath79_wdt_ioctl,
230         .open           = ath79_wdt_open,
231         .release        = ath79_wdt_release,
232 };
233 
234 static struct miscdevice ath79_wdt_miscdev = {
235         .minor = WATCHDOG_MINOR,
236         .name = "watchdog",
237         .fops = &ath79_wdt_fops,
238 };
239 
240 static int ath79_wdt_probe(struct platform_device *pdev)
241 {
242         struct resource *res;
243         u32 ctrl;
244         int err;
245 
246         if (wdt_base)
247                 return -EBUSY;
248 
249         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
250         wdt_base = devm_ioremap_resource(&pdev->dev, res);
251         if (IS_ERR(wdt_base))
252                 return PTR_ERR(wdt_base);
253 
254         wdt_clk = devm_clk_get(&pdev->dev, "wdt");
255         if (IS_ERR(wdt_clk))
256                 return PTR_ERR(wdt_clk);
257 
258         err = clk_enable(wdt_clk);
259         if (err)
260                 return err;
261 
262         wdt_freq = clk_get_rate(wdt_clk);
263         if (!wdt_freq) {
264                 err = -EINVAL;
265                 goto err_clk_disable;
266         }
267 
268         max_timeout = (0xfffffffful / wdt_freq);
269         if (timeout < 1 || timeout > max_timeout) {
270                 timeout = max_timeout;
271                 dev_info(&pdev->dev,
272                         "timeout value must be 0 < timeout < %d, using %d\n",
273                         max_timeout, timeout);
274         }
275 
276         ctrl = ath79_wdt_rr(WDOG_REG_CTRL);
277         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
278 
279         err = misc_register(&ath79_wdt_miscdev);
280         if (err) {
281                 dev_err(&pdev->dev,
282                         "unable to register misc device, err=%d\n", err);
283                 goto err_clk_disable;
284         }
285 
286         return 0;
287 
288 err_clk_disable:
289         clk_disable(wdt_clk);
290         return err;
291 }
292 
293 static int ath79_wdt_remove(struct platform_device *pdev)
294 {
295         misc_deregister(&ath79_wdt_miscdev);
296         clk_disable(wdt_clk);
297         return 0;
298 }
299 
300 static void ath97_wdt_shutdown(struct platform_device *pdev)
301 {
302         ath79_wdt_disable();
303 }
304 
305 #ifdef CONFIG_OF
306 static const struct of_device_id ath79_wdt_match[] = {
307         { .compatible = "qca,ar7130-wdt" },
308         {},
309 };
310 MODULE_DEVICE_TABLE(of, ath79_wdt_match);
311 #endif
312 
313 static struct platform_driver ath79_wdt_driver = {
314         .probe          = ath79_wdt_probe,
315         .remove         = ath79_wdt_remove,
316         .shutdown       = ath97_wdt_shutdown,
317         .driver         = {
318                 .name   = DRIVER_NAME,
319                 .owner  = THIS_MODULE,
320                 .of_match_table = of_match_ptr(ath79_wdt_match),
321         },
322 };
323 
324 module_platform_driver(ath79_wdt_driver);
325 
326 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
327 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
328 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
329 MODULE_LICENSE("GPL v2");
330 MODULE_ALIAS("platform:" DRIVER_NAME);
331 

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