2d22e996e9963cedaf656aa1c82867894d14c906
[sfrench/cifs-2.6.git] / drivers / watchdog / pika_wdt.c
1 /*
2  * PIKA FPGA based Watchdog Timer
3  *
4  * Copyright (c) 2008 PIKA Technologies
5  *   Sean MacLennan <smaclennan@pikatech.com>
6  */
7
8 #include <linux/init.h>
9 #include <linux/errno.h>
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/fs.h>
15 #include <linux/miscdevice.h>
16 #include <linux/watchdog.h>
17 #include <linux/reboot.h>
18 #include <linux/jiffies.h>
19 #include <linux/timer.h>
20 #include <linux/bitops.h>
21 #include <linux/uaccess.h>
22 #include <linux/io.h>
23 #include <linux/of_platform.h>
24
25 #define DRV_NAME "PIKA-WDT"
26 #define PFX DRV_NAME ": "
27
28 /* Hardware timeout in seconds */
29 #define WDT_HW_TIMEOUT 2
30
31 /* Timer heartbeat (500ms) */
32 #define WDT_TIMEOUT     (HZ/2)
33
34 /* User land timeout */
35 #define WDT_HEARTBEAT 15
36 static int heartbeat = WDT_HEARTBEAT;
37 module_param(heartbeat, int, 0);
38 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
39         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
40
41 static int nowayout = WATCHDOG_NOWAYOUT;
42 module_param(nowayout, int, 0);
43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
44         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
45
46 static struct {
47         void __iomem *fpga;
48         unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
49         unsigned long open;
50         char expect_close;
51         int bootstatus;
52         struct timer_list timer;        /* The timer that pings the watchdog */
53 } pikawdt_private;
54
55 static struct watchdog_info ident = {
56         .identity       = DRV_NAME,
57         .options        = WDIOF_CARDRESET |
58                           WDIOF_SETTIMEOUT |
59                           WDIOF_KEEPALIVEPING |
60                           WDIOF_MAGICCLOSE,
61 };
62
63 /*
64  * Reload the watchdog timer.  (ie, pat the watchdog)
65  */
66 static inline void pikawdt_reset(void)
67 {
68         /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
69          * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
70          *           Once enabled, it cannot be disabled. The watchdog can be
71          *           kicked by performing any write access to the reset
72          *           control register (this register).
73          * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
74          *           seconds. Valid ranges are 1 to 15 seconds. The value can
75          *           be modified dynamically.
76          */
77         unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
78         /* enable with max timeout - 15 seconds */
79         reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
80         out_be32(pikawdt_private.fpga + 0x14, reset);
81 }
82
83 /*
84  * Timer tick
85  */
86 static void pikawdt_ping(unsigned long data)
87 {
88         if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
89                         (!nowayout && !pikawdt_private.open)) {
90                 pikawdt_reset();
91                 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
92         } else
93                 printk(KERN_CRIT PFX "I will reset your machine !\n");
94 }
95
96
97 static void pikawdt_keepalive(void)
98 {
99         pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
100 }
101
102 static void pikawdt_start(void)
103 {
104         pikawdt_keepalive();
105         mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
106 }
107
108 /*
109  * Watchdog device is opened, and watchdog starts running.
110  */
111 static int pikawdt_open(struct inode *inode, struct file *file)
112 {
113         /* /dev/watchdog can only be opened once */
114         if (test_and_set_bit(0, &pikawdt_private.open))
115                 return -EBUSY;
116
117         pikawdt_start();
118
119         return nonseekable_open(inode, file);
120 }
121
122 /*
123  * Close the watchdog device.
124  */
125 static int pikawdt_release(struct inode *inode, struct file *file)
126 {
127         /* stop internal ping */
128         if (!pikawdt_private.expect_close)
129                 del_timer(&pikawdt_private.timer);
130
131         clear_bit(0, &pikawdt_private.open);
132         pikawdt_private.expect_close = 0;
133         return 0;
134 }
135
136 /*
137  * Pat the watchdog whenever device is written to.
138  */
139 static ssize_t pikawdt_write(struct file *file, const char __user *data,
140                              size_t len, loff_t *ppos)
141 {
142         if (!len)
143                 return 0;
144
145         /* Scan for magic character */
146         if (!nowayout) {
147                 size_t i;
148
149                 pikawdt_private.expect_close = 0;
150
151                 for (i = 0; i < len; i++) {
152                         char c;
153                         if (get_user(c, data + i))
154                                 return -EFAULT;
155                         if (c == 'V') {
156                                 pikawdt_private.expect_close = 42;
157                                 break;
158                         }
159                 }
160         }
161
162         pikawdt_keepalive();
163
164         return len;
165 }
166
167 /*
168  * Handle commands from user-space.
169  */
170 static long pikawdt_ioctl(struct file *file,
171                 unsigned int cmd, unsigned long arg)
172 {
173         void __user *argp = (void __user *)arg;
174         int __user *p = argp;
175         int new_value;
176
177         switch (cmd) {
178         case WDIOC_GETSUPPORT:
179                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
180
181         case WDIOC_GETSTATUS:
182                 return put_user(0, p);
183
184         case WDIOC_GETBOOTSTATUS:
185                 return put_user(pikawdt_private.bootstatus, p);
186
187         case WDIOC_KEEPALIVE:
188                 pikawdt_keepalive();
189                 return 0;
190
191         case WDIOC_SETTIMEOUT:
192                 if (get_user(new_value, p))
193                         return -EFAULT;
194
195                 heartbeat = new_value;
196                 pikawdt_keepalive();
197
198                 return put_user(new_value, p);  /* return current value */
199
200         case WDIOC_GETTIMEOUT:
201                 return put_user(heartbeat, p);
202         }
203         return -ENOTTY;
204 }
205
206
207 static const struct file_operations pikawdt_fops = {
208         .owner          = THIS_MODULE,
209         .llseek         = no_llseek,
210         .open           = pikawdt_open,
211         .release        = pikawdt_release,
212         .write          = pikawdt_write,
213         .unlocked_ioctl = pikawdt_ioctl,
214 };
215
216 static struct miscdevice pikawdt_miscdev = {
217         .minor  = WATCHDOG_MINOR,
218         .name   = "watchdog",
219         .fops   = &pikawdt_fops,
220 };
221
222 static int __init pikawdt_init(void)
223 {
224         struct device_node *np;
225         void __iomem *fpga;
226         static u32 post1;
227         int ret;
228
229         np = of_find_compatible_node(NULL, NULL, "pika,fpga");
230         if (np == NULL) {
231                 printk(KERN_ERR PFX "Unable to find fpga.\n");
232                 return -ENOENT;
233         }
234
235         pikawdt_private.fpga = of_iomap(np, 0);
236         of_node_put(np);
237         if (pikawdt_private.fpga == NULL) {
238                 printk(KERN_ERR PFX "Unable to map fpga.\n");
239                 return -ENOMEM;
240         }
241
242         ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
243
244         /* POST information is in the sd area. */
245         np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
246         if (np == NULL) {
247                 printk(KERN_ERR PFX "Unable to find fpga-sd.\n");
248                 ret = -ENOENT;
249                 goto out;
250         }
251
252         fpga = of_iomap(np, 0);
253         of_node_put(np);
254         if (fpga == NULL) {
255                 printk(KERN_ERR PFX "Unable to map fpga-sd.\n");
256                 ret = -ENOMEM;
257                 goto out;
258         }
259
260         /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
261          * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
262          *           timeout.
263          */
264         post1 = in_be32(fpga + 0x40);
265         if (post1 & 0x80000000)
266                 pikawdt_private.bootstatus = WDIOF_CARDRESET;
267
268         iounmap(fpga);
269
270         setup_timer(&pikawdt_private.timer, pikawdt_ping, 0);
271
272         ret = misc_register(&pikawdt_miscdev);
273         if (ret) {
274                 printk(KERN_ERR PFX "Unable to register miscdev.\n");
275                 goto out;
276         }
277
278         printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
279                                                         heartbeat, nowayout);
280         return 0;
281
282 out:
283         iounmap(pikawdt_private.fpga);
284         return ret;
285 }
286
287 static void __exit pikawdt_exit(void)
288 {
289         misc_deregister(&pikawdt_miscdev);
290
291         iounmap(pikawdt_private.fpga);
292 }
293
294 module_init(pikawdt_init);
295 module_exit(pikawdt_exit);
296
297 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
298 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
299 MODULE_LICENSE("GPL");
300 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
301