xref: /openbmc/linux/drivers/watchdog/pika_wdt.c (revision d0b73b48) 
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  */
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  */
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 
98 static void pikawdt_keepalive(void)
99 {
100 	pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
101 }
102 
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  */
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  */
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  */
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  */
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 
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 
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