xref: /openbmc/linux/drivers/watchdog/pika_wdt.c (revision 9cfc5c90) 
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_address.h>
26 #include <linux/of_platform.h>
27 
28 #define DRV_NAME "PIKA-WDT"
29 
30 /* Hardware timeout in seconds */
31 #define WDT_HW_TIMEOUT 2
32 
33 /* Timer heartbeat (500ms) */
34 #define WDT_TIMEOUT	(HZ/2)
35 
36 /* User land timeout */
37 #define WDT_HEARTBEAT 15
38 static int heartbeat = WDT_HEARTBEAT;
39 module_param(heartbeat, int, 0);
40 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
41 	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
42 
43 static bool nowayout = WATCHDOG_NOWAYOUT;
44 module_param(nowayout, bool, 0);
45 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
46 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
47 
48 static struct {
49 	void __iomem *fpga;
50 	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
51 	unsigned long open;
52 	char expect_close;
53 	int bootstatus;
54 	struct timer_list timer;	/* The timer that pings the watchdog */
55 } pikawdt_private;
56 
57 static struct watchdog_info ident = {
58 	.identity	= DRV_NAME,
59 	.options	= WDIOF_CARDRESET |
60 			  WDIOF_SETTIMEOUT |
61 			  WDIOF_KEEPALIVEPING |
62 			  WDIOF_MAGICCLOSE,
63 };
64 
65 /*
66  * Reload the watchdog timer.  (ie, pat the watchdog)
67  */
68 static inline void pikawdt_reset(void)
69 {
70 	/* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
71 	 * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
72 	 *           Once enabled, it cannot be disabled. The watchdog can be
73 	 *           kicked by performing any write access to the reset
74 	 *           control register (this register).
75 	 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
76 	 *           seconds. Valid ranges are 1 to 15 seconds. The value can
77 	 *           be modified dynamically.
78 	 */
79 	unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
80 	/* enable with max timeout - 15 seconds */
81 	reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
82 	out_be32(pikawdt_private.fpga + 0x14, reset);
83 }
84 
85 /*
86  * Timer tick
87  */
88 static void pikawdt_ping(unsigned long data)
89 {
90 	if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
91 			(!nowayout && !pikawdt_private.open)) {
92 		pikawdt_reset();
93 		mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
94 	} else
95 		pr_crit("I will reset your machine !\n");
96 }
97 
98 
99 static void pikawdt_keepalive(void)
100 {
101 	pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
102 }
103 
104 static void pikawdt_start(void)
105 {
106 	pikawdt_keepalive();
107 	mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
108 }
109 
110 /*
111  * Watchdog device is opened, and watchdog starts running.
112  */
113 static int pikawdt_open(struct inode *inode, struct file *file)
114 {
115 	/* /dev/watchdog can only be opened once */
116 	if (test_and_set_bit(0, &pikawdt_private.open))
117 		return -EBUSY;
118 
119 	pikawdt_start();
120 
121 	return nonseekable_open(inode, file);
122 }
123 
124 /*
125  * Close the watchdog device.
126  */
127 static int pikawdt_release(struct inode *inode, struct file *file)
128 {
129 	/* stop internal ping */
130 	if (!pikawdt_private.expect_close)
131 		del_timer(&pikawdt_private.timer);
132 
133 	clear_bit(0, &pikawdt_private.open);
134 	pikawdt_private.expect_close = 0;
135 	return 0;
136 }
137 
138 /*
139  * Pat the watchdog whenever device is written to.
140  */
141 static ssize_t pikawdt_write(struct file *file, const char __user *data,
142 			     size_t len, loff_t *ppos)
143 {
144 	if (!len)
145 		return 0;
146 
147 	/* Scan for magic character */
148 	if (!nowayout) {
149 		size_t i;
150 
151 		pikawdt_private.expect_close = 0;
152 
153 		for (i = 0; i < len; i++) {
154 			char c;
155 			if (get_user(c, data + i))
156 				return -EFAULT;
157 			if (c == 'V') {
158 				pikawdt_private.expect_close = 42;
159 				break;
160 			}
161 		}
162 	}
163 
164 	pikawdt_keepalive();
165 
166 	return len;
167 }
168 
169 /*
170  * Handle commands from user-space.
171  */
172 static long pikawdt_ioctl(struct file *file,
173 		unsigned int cmd, unsigned long arg)
174 {
175 	void __user *argp = (void __user *)arg;
176 	int __user *p = argp;
177 	int new_value;
178 
179 	switch (cmd) {
180 	case WDIOC_GETSUPPORT:
181 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
182 
183 	case WDIOC_GETSTATUS:
184 		return put_user(0, p);
185 
186 	case WDIOC_GETBOOTSTATUS:
187 		return put_user(pikawdt_private.bootstatus, p);
188 
189 	case WDIOC_KEEPALIVE:
190 		pikawdt_keepalive();
191 		return 0;
192 
193 	case WDIOC_SETTIMEOUT:
194 		if (get_user(new_value, p))
195 			return -EFAULT;
196 
197 		heartbeat = new_value;
198 		pikawdt_keepalive();
199 
200 		return put_user(new_value, p);  /* return current value */
201 
202 	case WDIOC_GETTIMEOUT:
203 		return put_user(heartbeat, p);
204 	}
205 	return -ENOTTY;
206 }
207 
208 
209 static const struct file_operations pikawdt_fops = {
210 	.owner		= THIS_MODULE,
211 	.llseek		= no_llseek,
212 	.open		= pikawdt_open,
213 	.release	= pikawdt_release,
214 	.write		= pikawdt_write,
215 	.unlocked_ioctl	= pikawdt_ioctl,
216 };
217 
218 static struct miscdevice pikawdt_miscdev = {
219 	.minor	= WATCHDOG_MINOR,
220 	.name	= "watchdog",
221 	.fops	= &pikawdt_fops,
222 };
223 
224 static int __init pikawdt_init(void)
225 {
226 	struct device_node *np;
227 	void __iomem *fpga;
228 	static u32 post1;
229 	int ret;
230 
231 	np = of_find_compatible_node(NULL, NULL, "pika,fpga");
232 	if (np == NULL) {
233 		pr_err("Unable to find fpga\n");
234 		return -ENOENT;
235 	}
236 
237 	pikawdt_private.fpga = of_iomap(np, 0);
238 	of_node_put(np);
239 	if (pikawdt_private.fpga == NULL) {
240 		pr_err("Unable to map fpga\n");
241 		return -ENOMEM;
242 	}
243 
244 	ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
245 
246 	/* POST information is in the sd area. */
247 	np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
248 	if (np == NULL) {
249 		pr_err("Unable to find fpga-sd\n");
250 		ret = -ENOENT;
251 		goto out;
252 	}
253 
254 	fpga = of_iomap(np, 0);
255 	of_node_put(np);
256 	if (fpga == NULL) {
257 		pr_err("Unable to map fpga-sd\n");
258 		ret = -ENOMEM;
259 		goto out;
260 	}
261 
262 	/* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
263 	 * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
264 	 *           timeout.
265 	 */
266 	post1 = in_be32(fpga + 0x40);
267 	if (post1 & 0x80000000)
268 		pikawdt_private.bootstatus = WDIOF_CARDRESET;
269 
270 	iounmap(fpga);
271 
272 	setup_timer(&pikawdt_private.timer, pikawdt_ping, 0);
273 
274 	ret = misc_register(&pikawdt_miscdev);
275 	if (ret) {
276 		pr_err("Unable to register miscdev\n");
277 		goto out;
278 	}
279 
280 	pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
281 		heartbeat, nowayout);
282 	return 0;
283 
284 out:
285 	iounmap(pikawdt_private.fpga);
286 	return ret;
287 }
288 
289 static void __exit pikawdt_exit(void)
290 {
291 	misc_deregister(&pikawdt_miscdev);
292 
293 	iounmap(pikawdt_private.fpga);
294 }
295 
296 module_init(pikawdt_init);
297 module_exit(pikawdt_exit);
298 
299 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
300 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
301 MODULE_LICENSE("GPL");
302