1 /*
2 * PIKA FPGA based Watchdog Timer
3 *
4 * Copyright (c) 2008 PIKA Technologies
5 * Sean MacLennan <smaclennan@pikatech.com>
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/init.h>
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/fs.h>
17 #include <linux/miscdevice.h>
18 #include <linux/watchdog.h>
19 #include <linux/reboot.h>
20 #include <linux/jiffies.h>
21 #include <linux/timer.h>
22 #include <linux/bitops.h>
23 #include <linux/uaccess.h>
24 #include <linux/io.h>
25 #include <linux/of_platform.h>
26
27 #define DRV_NAME "PIKA-WDT"
28
29 /* Hardware timeout in seconds */
30 #define WDT_HW_TIMEOUT 2
31
32 /* Timer heartbeat (500ms) */
33 #define WDT_TIMEOUT (HZ/2)
34
35 /* User land timeout */
36 #define WDT_HEARTBEAT 15
37 static int heartbeat = WDT_HEARTBEAT;
38 module_param(heartbeat, int, 0);
39 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
40 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
41
42 static bool nowayout = WATCHDOG_NOWAYOUT;
43 module_param(nowayout, bool, 0);
44 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
45 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
46
47 static struct {
48 void __iomem *fpga;
49 unsigned long next_heartbeat; /* the next_heartbeat for the timer */
50 unsigned long open;
51 char expect_close;
52 int bootstatus;
53 struct timer_list timer; /* The timer that pings the watchdog */
54 } pikawdt_private;
55
56 static struct watchdog_info ident = {
57 .identity = DRV_NAME,
58 .options = WDIOF_CARDRESET |
59 WDIOF_SETTIMEOUT |
60 WDIOF_KEEPALIVEPING |
61 WDIOF_MAGICCLOSE,
62 };
63
64 /*
65 * Reload the watchdog timer. (ie, pat the watchdog)
66 */
pikawdt_reset(void)67 static inline void pikawdt_reset(void)
68 {
69 /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
70 * Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled.
71 * Once enabled, it cannot be disabled. The watchdog can be
72 * kicked by performing any write access to the reset
73 * control register (this register).
74 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
75 * seconds. Valid ranges are 1 to 15 seconds. The value can
76 * be modified dynamically.
77 */
78 unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
79 /* enable with max timeout - 15 seconds */
80 reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
81 out_be32(pikawdt_private.fpga + 0x14, reset);
82 }
83
84 /*
85 * Timer tick
86 */
pikawdt_ping(unsigned long data)87 static void pikawdt_ping(unsigned long data)
88 {
89 if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
90 (!nowayout && !pikawdt_private.open)) {
91 pikawdt_reset();
92 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
93 } else
94 pr_crit("I will reset your machine !\n");
95 }
96
97
pikawdt_keepalive(void)98 static void pikawdt_keepalive(void)
99 {
100 pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
101 }
102
pikawdt_start(void)103 static void pikawdt_start(void)
104 {
105 pikawdt_keepalive();
106 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
107 }
108
109 /*
110 * Watchdog device is opened, and watchdog starts running.
111 */
pikawdt_open(struct inode * inode,struct file * file)112 static int pikawdt_open(struct inode *inode, struct file *file)
113 {
114 /* /dev/watchdog can only be opened once */
115 if (test_and_set_bit(0, &pikawdt_private.open))
116 return -EBUSY;
117
118 pikawdt_start();
119
120 return nonseekable_open(inode, file);
121 }
122
123 /*
124 * Close the watchdog device.
125 */
pikawdt_release(struct inode * inode,struct file * file)126 static int pikawdt_release(struct inode *inode, struct file *file)
127 {
128 /* stop internal ping */
129 if (!pikawdt_private.expect_close)
130 del_timer(&pikawdt_private.timer);
131
132 clear_bit(0, &pikawdt_private.open);
133 pikawdt_private.expect_close = 0;
134 return 0;
135 }
136
137 /*
138 * Pat the watchdog whenever device is written to.
139 */
pikawdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)140 static ssize_t pikawdt_write(struct file *file, const char __user *data,
141 size_t len, loff_t *ppos)
142 {
143 if (!len)
144 return 0;
145
146 /* Scan for magic character */
147 if (!nowayout) {
148 size_t i;
149
150 pikawdt_private.expect_close = 0;
151
152 for (i = 0; i < len; i++) {
153 char c;
154 if (get_user(c, data + i))
155 return -EFAULT;
156 if (c == 'V') {
157 pikawdt_private.expect_close = 42;
158 break;
159 }
160 }
161 }
162
163 pikawdt_keepalive();
164
165 return len;
166 }
167
168 /*
169 * Handle commands from user-space.
170 */
pikawdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)171 static long pikawdt_ioctl(struct file *file,
172 unsigned int cmd, unsigned long arg)
173 {
174 void __user *argp = (void __user *)arg;
175 int __user *p = argp;
176 int new_value;
177
178 switch (cmd) {
179 case WDIOC_GETSUPPORT:
180 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
181
182 case WDIOC_GETSTATUS:
183 return put_user(0, p);
184
185 case WDIOC_GETBOOTSTATUS:
186 return put_user(pikawdt_private.bootstatus, p);
187
188 case WDIOC_KEEPALIVE:
189 pikawdt_keepalive();
190 return 0;
191
192 case WDIOC_SETTIMEOUT:
193 if (get_user(new_value, p))
194 return -EFAULT;
195
196 heartbeat = new_value;
197 pikawdt_keepalive();
198
199 return put_user(new_value, p); /* return current value */
200
201 case WDIOC_GETTIMEOUT:
202 return put_user(heartbeat, p);
203 }
204 return -ENOTTY;
205 }
206
207
208 static const struct file_operations pikawdt_fops = {
209 .owner = THIS_MODULE,
210 .llseek = no_llseek,
211 .open = pikawdt_open,
212 .release = pikawdt_release,
213 .write = pikawdt_write,
214 .unlocked_ioctl = pikawdt_ioctl,
215 };
216
217 static struct miscdevice pikawdt_miscdev = {
218 .minor = WATCHDOG_MINOR,
219 .name = "watchdog",
220 .fops = &pikawdt_fops,
221 };
222
pikawdt_init(void)223 static int __init pikawdt_init(void)
224 {
225 struct device_node *np;
226 void __iomem *fpga;
227 static u32 post1;
228 int ret;
229
230 np = of_find_compatible_node(NULL, NULL, "pika,fpga");
231 if (np == NULL) {
232 pr_err("Unable to find fpga\n");
233 return -ENOENT;
234 }
235
236 pikawdt_private.fpga = of_iomap(np, 0);
237 of_node_put(np);
238 if (pikawdt_private.fpga == NULL) {
239 pr_err("Unable to map fpga\n");
240 return -ENOMEM;
241 }
242
243 ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
244
245 /* POST information is in the sd area. */
246 np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
247 if (np == NULL) {
248 pr_err("Unable to find fpga-sd\n");
249 ret = -ENOENT;
250 goto out;
251 }
252
253 fpga = of_iomap(np, 0);
254 of_node_put(np);
255 if (fpga == NULL) {
256 pr_err("Unable to map fpga-sd\n");
257 ret = -ENOMEM;
258 goto out;
259 }
260
261 /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
262 * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog
263 * timeout.
264 */
265 post1 = in_be32(fpga + 0x40);
266 if (post1 & 0x80000000)
267 pikawdt_private.bootstatus = WDIOF_CARDRESET;
268
269 iounmap(fpga);
270
271 setup_timer(&pikawdt_private.timer, pikawdt_ping, 0);
272
273 ret = misc_register(&pikawdt_miscdev);
274 if (ret) {
275 pr_err("Unable to register miscdev\n");
276 goto out;
277 }
278
279 pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
280 heartbeat, nowayout);
281 return 0;
282
283 out:
284 iounmap(pikawdt_private.fpga);
285 return ret;
286 }
287
pikawdt_exit(void)288 static void __exit pikawdt_exit(void)
289 {
290 misc_deregister(&pikawdt_miscdev);
291
292 iounmap(pikawdt_private.fpga);
293 }
294
295 module_init(pikawdt_init);
296 module_exit(pikawdt_exit);
297
298 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
299 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
300 MODULE_LICENSE("GPL");
301 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
302
303