parport_pc: show the detection of a 2 serial port ITE8874 chip
[linux-2.6.git] / drivers / watchdog / ar7_wdt.c
1 /*
2  * drivers/watchdog/ar7_wdt.c
3  *
4  * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
5  * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
6  *
7  * Some code taken from:
8  * National Semiconductor SCx200 Watchdog support
9  * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
24  */
25
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/errno.h>
29 #include <linux/init.h>
30 #include <linux/miscdevice.h>
31 #include <linux/platform_device.h>
32 #include <linux/watchdog.h>
33 #include <linux/fs.h>
34 #include <linux/ioport.h>
35 #include <linux/io.h>
36 #include <linux/uaccess.h>
37 #include <linux/clk.h>
38
39 #include <asm/addrspace.h>
40 #include <asm/mach-ar7/ar7.h>
41
42 #define DRVNAME "ar7_wdt"
43 #define LONGNAME "TI AR7 Watchdog Timer"
44
45 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
46 MODULE_DESCRIPTION(LONGNAME);
47 MODULE_LICENSE("GPL");
48 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
49
50 static int margin = 60;
51 module_param(margin, int, 0);
52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
53
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 module_param(nowayout, int, 0);
56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
57
58 #define READ_REG(x) readl((void __iomem *)&(x))
59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
60
61 struct ar7_wdt {
62         u32 kick_lock;
63         u32 kick;
64         u32 change_lock;
65         u32 change;
66         u32 disable_lock;
67         u32 disable;
68         u32 prescale_lock;
69         u32 prescale;
70 };
71
72 static unsigned long wdt_is_open;
73 static spinlock_t wdt_lock;
74 static unsigned expect_close;
75
76 /* XXX currently fixed, allows max margin ~68.72 secs */
77 #define prescale_value 0xffff
78
79 /* Resource of the WDT registers */
80 static struct resource *ar7_regs_wdt;
81 /* Pointer to the remapped WDT IO space */
82 static struct ar7_wdt *ar7_wdt;
83
84 static struct clk *vbus_clk;
85
86 static void ar7_wdt_kick(u32 value)
87 {
88         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
89         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
90                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
91                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
92                         WRITE_REG(ar7_wdt->kick, value);
93                         return;
94                 }
95         }
96         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
97 }
98
99 static void ar7_wdt_prescale(u32 value)
100 {
101         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
102         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
103                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
104                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
105                         WRITE_REG(ar7_wdt->prescale, value);
106                         return;
107                 }
108         }
109         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
110 }
111
112 static void ar7_wdt_change(u32 value)
113 {
114         WRITE_REG(ar7_wdt->change_lock, 0x6666);
115         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
116                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
117                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
118                         WRITE_REG(ar7_wdt->change, value);
119                         return;
120                 }
121         }
122         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
123 }
124
125 static void ar7_wdt_disable(u32 value)
126 {
127         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
128         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
129                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
130                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
131                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
132                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
133                                 WRITE_REG(ar7_wdt->disable, value);
134                                 return;
135                         }
136                 }
137         }
138         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
139 }
140
141 static void ar7_wdt_update_margin(int new_margin)
142 {
143         u32 change;
144         u32 vbus_rate;
145
146         vbus_rate = clk_get_rate(vbus_clk);
147         change = new_margin * (vbus_rate / prescale_value);
148         if (change < 1)
149                 change = 1;
150         if (change > 0xffff)
151                 change = 0xffff;
152         ar7_wdt_change(change);
153         margin = change * prescale_value / vbus_rate;
154         printk(KERN_INFO DRVNAME
155                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
156                margin, prescale_value, change, vbus_rate);
157 }
158
159 static void ar7_wdt_enable_wdt(void)
160 {
161         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
162         ar7_wdt_disable(1);
163         ar7_wdt_kick(1);
164 }
165
166 static void ar7_wdt_disable_wdt(void)
167 {
168         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
169         ar7_wdt_disable(0);
170 }
171
172 static int ar7_wdt_open(struct inode *inode, struct file *file)
173 {
174         /* only allow one at a time */
175         if (test_and_set_bit(0, &wdt_is_open))
176                 return -EBUSY;
177         ar7_wdt_enable_wdt();
178         expect_close = 0;
179
180         return nonseekable_open(inode, file);
181 }
182
183 static int ar7_wdt_release(struct inode *inode, struct file *file)
184 {
185         if (!expect_close)
186                 printk(KERN_WARNING DRVNAME
187                 ": watchdog device closed unexpectedly,"
188                 "will not disable the watchdog timer\n");
189         else if (!nowayout)
190                 ar7_wdt_disable_wdt();
191         clear_bit(0, &wdt_is_open);
192         return 0;
193 }
194
195 static ssize_t ar7_wdt_write(struct file *file, const char *data,
196                              size_t len, loff_t *ppos)
197 {
198         /* check for a magic close character */
199         if (len) {
200                 size_t i;
201
202                 spin_lock(&wdt_lock);
203                 ar7_wdt_kick(1);
204                 spin_unlock(&wdt_lock);
205
206                 expect_close = 0;
207                 for (i = 0; i < len; ++i) {
208                         char c;
209                         if (get_user(c, data + i))
210                                 return -EFAULT;
211                         if (c == 'V')
212                                 expect_close = 1;
213                 }
214
215         }
216         return len;
217 }
218
219 static long ar7_wdt_ioctl(struct file *file,
220                                         unsigned int cmd, unsigned long arg)
221 {
222         static const struct watchdog_info ident = {
223                 .identity = LONGNAME,
224                 .firmware_version = 1,
225                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
226                                                 WDIOF_MAGICCLOSE),
227         };
228         int new_margin;
229
230         switch (cmd) {
231         case WDIOC_GETSUPPORT:
232                 if (copy_to_user((struct watchdog_info *)arg, &ident,
233                                 sizeof(ident)))
234                         return -EFAULT;
235                 return 0;
236         case WDIOC_GETSTATUS:
237         case WDIOC_GETBOOTSTATUS:
238                 if (put_user(0, (int *)arg))
239                         return -EFAULT;
240                 return 0;
241         case WDIOC_KEEPALIVE:
242                 ar7_wdt_kick(1);
243                 return 0;
244         case WDIOC_SETTIMEOUT:
245                 if (get_user(new_margin, (int *)arg))
246                         return -EFAULT;
247                 if (new_margin < 1)
248                         return -EINVAL;
249
250                 spin_lock(&wdt_lock);
251                 ar7_wdt_update_margin(new_margin);
252                 ar7_wdt_kick(1);
253                 spin_unlock(&wdt_lock);
254
255         case WDIOC_GETTIMEOUT:
256                 if (put_user(margin, (int *)arg))
257                         return -EFAULT;
258                 return 0;
259         default:
260                 return -ENOTTY;
261         }
262 }
263
264 static const struct file_operations ar7_wdt_fops = {
265         .owner          = THIS_MODULE,
266         .write          = ar7_wdt_write,
267         .unlocked_ioctl = ar7_wdt_ioctl,
268         .open           = ar7_wdt_open,
269         .release        = ar7_wdt_release,
270 };
271
272 static struct miscdevice ar7_wdt_miscdev = {
273         .minor          = WATCHDOG_MINOR,
274         .name           = "watchdog",
275         .fops           = &ar7_wdt_fops,
276 };
277
278 static int __devinit ar7_wdt_probe(struct platform_device *pdev)
279 {
280         int rc;
281
282         spin_lock_init(&wdt_lock);
283
284         ar7_regs_wdt =
285                 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
286         if (!ar7_regs_wdt) {
287                 printk(KERN_ERR DRVNAME ": could not get registers resource\n");
288                 rc = -ENODEV;
289                 goto out;
290         }
291
292         if (!request_mem_region(ar7_regs_wdt->start,
293                                 resource_size(ar7_regs_wdt), LONGNAME)) {
294                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
295                 rc = -EBUSY;
296                 goto out;
297         }
298
299         ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
300         if (!ar7_wdt) {
301                 printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
302                 rc = -ENXIO;
303                 goto out_mem_region;
304         }
305
306         vbus_clk = clk_get(NULL, "vbus");
307         if (IS_ERR(vbus_clk)) {
308                 printk(KERN_ERR DRVNAME ": could not get vbus clock\n");
309                 rc = PTR_ERR(vbus_clk);
310                 goto out_mem_region;
311         }
312
313         ar7_wdt_disable_wdt();
314         ar7_wdt_prescale(prescale_value);
315         ar7_wdt_update_margin(margin);
316
317         rc = misc_register(&ar7_wdt_miscdev);
318         if (rc) {
319                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
320                 goto out_alloc;
321         }
322         goto out;
323
324 out_alloc:
325         iounmap(ar7_wdt);
326 out_mem_region:
327         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
328 out:
329         return rc;
330 }
331
332 static int __devexit ar7_wdt_remove(struct platform_device *pdev)
333 {
334         misc_deregister(&ar7_wdt_miscdev);
335         iounmap(ar7_wdt);
336         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
337
338         return 0;
339 }
340
341 static void ar7_wdt_shutdown(struct platform_device *pdev)
342 {
343         if (!nowayout)
344                 ar7_wdt_disable_wdt();
345 }
346
347 static struct platform_driver ar7_wdt_driver = {
348         .probe = ar7_wdt_probe,
349         .remove = __devexit_p(ar7_wdt_remove),
350         .shutdown = ar7_wdt_shutdown,
351         .driver = {
352                 .owner = THIS_MODULE,
353                 .name = "ar7_wdt",
354         },
355 };
356
357 static int __init ar7_wdt_init(void)
358 {
359         return platform_driver_register(&ar7_wdt_driver);
360 }
361
362 static void __exit ar7_wdt_cleanup(void)
363 {
364         platform_driver_unregister(&ar7_wdt_driver);
365 }
366
367 module_init(ar7_wdt_init);
368 module_exit(ar7_wdt_cleanup);