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Linux/drivers/watchdog/nuc900_wdt.c

  1 /*
  2  * Copyright (c) 2009 Nuvoton technology corporation.
  3  *
  4  * Wan ZongShun <mcuos.com@gmail.com>
  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 as published by
  8  * the Free Software Foundation;version 2 of the License.
  9  *
 10  */
 11 
 12 #include <linux/bitops.h>
 13 #include <linux/errno.h>
 14 #include <linux/fs.h>
 15 #include <linux/init.h>
 16 #include <linux/io.h>
 17 #include <linux/clk.h>
 18 #include <linux/kernel.h>
 19 #include <linux/miscdevice.h>
 20 #include <linux/module.h>
 21 #include <linux/moduleparam.h>
 22 #include <linux/platform_device.h>
 23 #include <linux/slab.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/types.h>
 26 #include <linux/watchdog.h>
 27 #include <linux/uaccess.h>
 28 
 29 #define REG_WTCR                0x1c
 30 #define WTCLK                   (0x01 << 10)
 31 #define WTE                     (0x01 << 7)     /*wdt enable*/
 32 #define WTIS                    (0x03 << 4)
 33 #define WTIF                    (0x01 << 3)
 34 #define WTRF                    (0x01 << 2)
 35 #define WTRE                    (0x01 << 1)
 36 #define WTR                     (0x01 << 0)
 37 /*
 38  * The watchdog time interval can be calculated via following formula:
 39  * WTIS         real time interval (formula)
 40  * 0x00         ((2^ 14 ) * ((external crystal freq) / 256))seconds
 41  * 0x01         ((2^ 16 ) * ((external crystal freq) / 256))seconds
 42  * 0x02         ((2^ 18 ) * ((external crystal freq) / 256))seconds
 43  * 0x03         ((2^ 20 ) * ((external crystal freq) / 256))seconds
 44  *
 45  * The external crystal freq is 15Mhz in the nuc900 evaluation board.
 46  * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
 47  * 0x03 = +- 16.92 seconds..
 48  */
 49 #define WDT_HW_TIMEOUT          0x02
 50 #define WDT_TIMEOUT             (HZ/2)
 51 #define WDT_HEARTBEAT           15
 52 
 53 static int heartbeat = WDT_HEARTBEAT;
 54 module_param(heartbeat, int, 0);
 55 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
 56         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
 57 
 58 static bool nowayout = WATCHDOG_NOWAYOUT;
 59 module_param(nowayout, bool, 0);
 60 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
 61         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 62 
 63 struct nuc900_wdt {
 64         struct clk       *wdt_clock;
 65         struct platform_device *pdev;
 66         void __iomem     *wdt_base;
 67         char             expect_close;
 68         struct timer_list timer;
 69         spinlock_t       wdt_lock;
 70         unsigned long next_heartbeat;
 71 };
 72 
 73 static unsigned long nuc900wdt_busy;
 74 static struct nuc900_wdt *nuc900_wdt;
 75 
 76 static inline void nuc900_wdt_keepalive(void)
 77 {
 78         unsigned int val;
 79 
 80         spin_lock(&nuc900_wdt->wdt_lock);
 81 
 82         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 83         val |= (WTR | WTIF);
 84         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 85 
 86         spin_unlock(&nuc900_wdt->wdt_lock);
 87 }
 88 
 89 static inline void nuc900_wdt_start(void)
 90 {
 91         unsigned int val;
 92 
 93         spin_lock(&nuc900_wdt->wdt_lock);
 94 
 95         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 96         val |= (WTRE | WTE | WTR | WTCLK | WTIF);
 97         val &= ~WTIS;
 98         val |= (WDT_HW_TIMEOUT << 0x04);
 99         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
100 
101         spin_unlock(&nuc900_wdt->wdt_lock);
102 
103         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
104         mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
105 }
106 
107 static inline void nuc900_wdt_stop(void)
108 {
109         unsigned int val;
110 
111         del_timer(&nuc900_wdt->timer);
112 
113         spin_lock(&nuc900_wdt->wdt_lock);
114 
115         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
116         val &= ~WTE;
117         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
118 
119         spin_unlock(&nuc900_wdt->wdt_lock);
120 }
121 
122 static inline void nuc900_wdt_ping(void)
123 {
124         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
125 }
126 
127 static int nuc900_wdt_open(struct inode *inode, struct file *file)
128 {
129 
130         if (test_and_set_bit(0, &nuc900wdt_busy))
131                 return -EBUSY;
132 
133         nuc900_wdt_start();
134 
135         return nonseekable_open(inode, file);
136 }
137 
138 static int nuc900_wdt_close(struct inode *inode, struct file *file)
139 {
140         if (nuc900_wdt->expect_close == 42)
141                 nuc900_wdt_stop();
142         else {
143                 dev_crit(&nuc900_wdt->pdev->dev,
144                         "Unexpected close, not stopping watchdog!\n");
145                 nuc900_wdt_ping();
146         }
147 
148         nuc900_wdt->expect_close = 0;
149         clear_bit(0, &nuc900wdt_busy);
150         return 0;
151 }
152 
153 static const struct watchdog_info nuc900_wdt_info = {
154         .identity       = "nuc900 watchdog",
155         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
156                                                 WDIOF_MAGICCLOSE,
157 };
158 
159 static long nuc900_wdt_ioctl(struct file *file,
160                                         unsigned int cmd, unsigned long arg)
161 {
162         void __user *argp = (void __user *)arg;
163         int __user *p = argp;
164         int new_value;
165 
166         switch (cmd) {
167         case WDIOC_GETSUPPORT:
168                 return copy_to_user(argp, &nuc900_wdt_info,
169                                 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
170         case WDIOC_GETSTATUS:
171         case WDIOC_GETBOOTSTATUS:
172                 return put_user(0, p);
173 
174         case WDIOC_KEEPALIVE:
175                 nuc900_wdt_ping();
176                 return 0;
177 
178         case WDIOC_SETTIMEOUT:
179                 if (get_user(new_value, p))
180                         return -EFAULT;
181 
182                 heartbeat = new_value;
183                 nuc900_wdt_ping();
184 
185                 return put_user(new_value, p);
186         case WDIOC_GETTIMEOUT:
187                 return put_user(heartbeat, p);
188         default:
189                 return -ENOTTY;
190         }
191 }
192 
193 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
194                                                 size_t len, loff_t *ppos)
195 {
196         if (!len)
197                 return 0;
198 
199         /* Scan for magic character */
200         if (!nowayout) {
201                 size_t i;
202 
203                 nuc900_wdt->expect_close = 0;
204 
205                 for (i = 0; i < len; i++) {
206                         char c;
207                         if (get_user(c, data + i))
208                                 return -EFAULT;
209                         if (c == 'V') {
210                                 nuc900_wdt->expect_close = 42;
211                                 break;
212                         }
213                 }
214         }
215 
216         nuc900_wdt_ping();
217         return len;
218 }
219 
220 static void nuc900_wdt_timer_ping(unsigned long data)
221 {
222         if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
223                 nuc900_wdt_keepalive();
224                 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
225         } else
226                 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
227 }
228 
229 static const struct file_operations nuc900wdt_fops = {
230         .owner          = THIS_MODULE,
231         .llseek         = no_llseek,
232         .unlocked_ioctl = nuc900_wdt_ioctl,
233         .open           = nuc900_wdt_open,
234         .release        = nuc900_wdt_close,
235         .write          = nuc900_wdt_write,
236 };
237 
238 static struct miscdevice nuc900wdt_miscdev = {
239         .minor          = WATCHDOG_MINOR,
240         .name           = "watchdog",
241         .fops           = &nuc900wdt_fops,
242 };
243 
244 static int nuc900wdt_probe(struct platform_device *pdev)
245 {
246         struct resource *res;
247         int ret = 0;
248 
249         nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
250                                 GFP_KERNEL);
251         if (!nuc900_wdt)
252                 return -ENOMEM;
253 
254         nuc900_wdt->pdev = pdev;
255 
256         spin_lock_init(&nuc900_wdt->wdt_lock);
257 
258         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
259         nuc900_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
260         if (IS_ERR(nuc900_wdt->wdt_base))
261                 return PTR_ERR(nuc900_wdt->wdt_base);
262 
263         nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
264         if (IS_ERR(nuc900_wdt->wdt_clock)) {
265                 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
266                 return PTR_ERR(nuc900_wdt->wdt_clock);
267         }
268 
269         clk_enable(nuc900_wdt->wdt_clock);
270 
271         setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
272 
273         ret = misc_register(&nuc900wdt_miscdev);
274         if (ret) {
275                 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
276                         WATCHDOG_MINOR, ret);
277                 goto err_clk;
278         }
279 
280         return 0;
281 
282 err_clk:
283         clk_disable(nuc900_wdt->wdt_clock);
284         return ret;
285 }
286 
287 static int nuc900wdt_remove(struct platform_device *pdev)
288 {
289         misc_deregister(&nuc900wdt_miscdev);
290 
291         clk_disable(nuc900_wdt->wdt_clock);
292 
293         return 0;
294 }
295 
296 static struct platform_driver nuc900wdt_driver = {
297         .probe          = nuc900wdt_probe,
298         .remove         = nuc900wdt_remove,
299         .driver         = {
300                 .name   = "nuc900-wdt",
301                 .owner  = THIS_MODULE,
302         },
303 };
304 
305 module_platform_driver(nuc900wdt_driver);
306 
307 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
308 MODULE_DESCRIPTION("Watchdog driver for NUC900");
309 MODULE_LICENSE("GPL");
310 MODULE_ALIAS("platform:nuc900-wdt");
311 

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