1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * PIKA FPGA based Watchdog Timer
4  *
5  * Copyright (c) 2008 PIKA Technologies
6  *   Sean MacLennan <smaclennan@pikatech.com>
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 
11 #include <linux/init.h>
12 #include <linux/errno.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/fs.h>
18 #include <linux/miscdevice.h>
19 #include <linux/watchdog.h>
20 #include <linux/reboot.h>
21 #include <linux/jiffies.h>
22 #include <linux/timer.h>
23 #include <linux/bitops.h>
24 #include <linux/uaccess.h>
25 #include <linux/io.h>
26 #include <linux/of_address.h>
27 #include <linux/of_platform.h>
28 
29 #define DRV_NAME "PIKA-WDT"
30 
31 /* Hardware timeout in seconds */
32 #define WDT_HW_TIMEOUT 2
33 
34 /* Timer heartbeat (500ms) */
35 #define WDT_TIMEOUT	(HZ/2)
36 
37 /* User land timeout */
38 #define WDT_HEARTBEAT 15
39 static int heartbeat = WDT_HEARTBEAT;
40 module_param(heartbeat, int, 0);
41 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
42 	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
43 
44 static bool nowayout = WATCHDOG_NOWAYOUT;
45 module_param(nowayout, bool, 0);
46 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
47 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
48 
49 static struct {
50 	void __iomem *fpga;
51 	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
52 	unsigned long open;
53 	char expect_close;
54 	int bootstatus;
55 	struct timer_list timer;	/* The timer that pings the watchdog */
56 } pikawdt_private;
57 
58 static struct watchdog_info ident __ro_after_init = {
59 	.identity	= DRV_NAME,
60 	.options	= WDIOF_CARDRESET |
61 			  WDIOF_SETTIMEOUT |
62 			  WDIOF_KEEPALIVEPING |
63 			  WDIOF_MAGICCLOSE,
64 };
65 
66 /*
67  * Reload the watchdog timer.  (ie, pat the watchdog)
68  */
pikawdt_reset(void)69 static inline void pikawdt_reset(void)
70 {
71 	/* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
72 	 * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
73 	 *           Once enabled, it cannot be disabled. The watchdog can be
74 	 *           kicked by performing any write access to the reset
75 	 *           control register (this register).
76 	 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
77 	 *           seconds. Valid ranges are 1 to 15 seconds. The value can
78 	 *           be modified dynamically.
79 	 */
80 	unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
81 	/* enable with max timeout - 15 seconds */
82 	reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
83 	out_be32(pikawdt_private.fpga + 0x14, reset);
84 }
85 
86 /*
87  * Timer tick
88  */
pikawdt_ping(struct timer_list * unused)89 static void pikawdt_ping(struct timer_list *unused)
90 {
91 	if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
92 			(!nowayout && !pikawdt_private.open)) {
93 		pikawdt_reset();
94 		mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
95 	} else
96 		pr_crit("I will reset your machine !\n");
97 }
98 
99 
pikawdt_keepalive(void)100 static void pikawdt_keepalive(void)
101 {
102 	pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
103 }
104 
pikawdt_start(void)105 static void pikawdt_start(void)
106 {
107 	pikawdt_keepalive();
108 	mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
109 }
110 
111 /*
112  * Watchdog device is opened, and watchdog starts running.
113  */
pikawdt_open(struct inode * inode,struct file * file)114 static int pikawdt_open(struct inode *inode, struct file *file)
115 {
116 	/* /dev/watchdog can only be opened once */
117 	if (test_and_set_bit(0, &pikawdt_private.open))
118 		return -EBUSY;
119 
120 	pikawdt_start();
121 
122 	return stream_open(inode, file);
123 }
124 
125 /*
126  * Close the watchdog device.
127  */
pikawdt_release(struct inode * inode,struct file * file)128 static int pikawdt_release(struct inode *inode, struct file *file)
129 {
130 	/* stop internal ping */
131 	if (!pikawdt_private.expect_close)
132 		del_timer(&pikawdt_private.timer);
133 
134 	clear_bit(0, &pikawdt_private.open);
135 	pikawdt_private.expect_close = 0;
136 	return 0;
137 }
138 
139 /*
140  * Pat the watchdog whenever device is written to.
141  */
pikawdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)142 static ssize_t pikawdt_write(struct file *file, const char __user *data,
143 			     size_t len, loff_t *ppos)
144 {
145 	if (!len)
146 		return 0;
147 
148 	/* Scan for magic character */
149 	if (!nowayout) {
150 		size_t i;
151 
152 		pikawdt_private.expect_close = 0;
153 
154 		for (i = 0; i < len; i++) {
155 			char c;
156 			if (get_user(c, data + i))
157 				return -EFAULT;
158 			if (c == 'V') {
159 				pikawdt_private.expect_close = 42;
160 				break;
161 			}
162 		}
163 	}
164 
165 	pikawdt_keepalive();
166 
167 	return len;
168 }
169 
170 /*
171  * Handle commands from user-space.
172  */
pikawdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)173 static long pikawdt_ioctl(struct file *file,
174 		unsigned int cmd, unsigned long arg)
175 {
176 	void __user *argp = (void __user *)arg;
177 	int __user *p = argp;
178 	int new_value;
179 
180 	switch (cmd) {
181 	case WDIOC_GETSUPPORT:
182 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
183 
184 	case WDIOC_GETSTATUS:
185 		return put_user(0, p);
186 
187 	case WDIOC_GETBOOTSTATUS:
188 		return put_user(pikawdt_private.bootstatus, p);
189 
190 	case WDIOC_KEEPALIVE:
191 		pikawdt_keepalive();
192 		return 0;
193 
194 	case WDIOC_SETTIMEOUT:
195 		if (get_user(new_value, p))
196 			return -EFAULT;
197 
198 		heartbeat = new_value;
199 		pikawdt_keepalive();
200 
201 		return put_user(new_value, p);  /* return current value */
202 
203 	case WDIOC_GETTIMEOUT:
204 		return put_user(heartbeat, p);
205 	}
206 	return -ENOTTY;
207 }
208 
209 
210 static const struct file_operations pikawdt_fops = {
211 	.owner		= THIS_MODULE,
212 	.llseek		= no_llseek,
213 	.open		= pikawdt_open,
214 	.release	= pikawdt_release,
215 	.write		= pikawdt_write,
216 	.unlocked_ioctl	= pikawdt_ioctl,
217 	.compat_ioctl	= compat_ptr_ioctl,
218 };
219 
220 static struct miscdevice pikawdt_miscdev = {
221 	.minor	= WATCHDOG_MINOR,
222 	.name	= "watchdog",
223 	.fops	= &pikawdt_fops,
224 };
225 
pikawdt_init(void)226 static int __init pikawdt_init(void)
227 {
228 	struct device_node *np;
229 	void __iomem *fpga;
230 	u32 post1;
231 	int ret;
232 
233 	np = of_find_compatible_node(NULL, NULL, "pika,fpga");
234 	if (np == NULL) {
235 		pr_err("Unable to find fpga\n");
236 		return -ENOENT;
237 	}
238 
239 	pikawdt_private.fpga = of_iomap(np, 0);
240 	of_node_put(np);
241 	if (pikawdt_private.fpga == NULL) {
242 		pr_err("Unable to map fpga\n");
243 		return -ENOMEM;
244 	}
245 
246 	ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
247 
248 	/* POST information is in the sd area. */
249 	np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
250 	if (np == NULL) {
251 		pr_err("Unable to find fpga-sd\n");
252 		ret = -ENOENT;
253 		goto out;
254 	}
255 
256 	fpga = of_iomap(np, 0);
257 	of_node_put(np);
258 	if (fpga == NULL) {
259 		pr_err("Unable to map fpga-sd\n");
260 		ret = -ENOMEM;
261 		goto out;
262 	}
263 
264 	/* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
265 	 * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
266 	 *           timeout.
267 	 */
268 	post1 = in_be32(fpga + 0x40);
269 	if (post1 & 0x80000000)
270 		pikawdt_private.bootstatus = WDIOF_CARDRESET;
271 
272 	iounmap(fpga);
273 
274 	timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
275 
276 	ret = misc_register(&pikawdt_miscdev);
277 	if (ret) {
278 		pr_err("Unable to register miscdev\n");
279 		goto out;
280 	}
281 
282 	pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
283 		heartbeat, nowayout);
284 	return 0;
285 
286 out:
287 	iounmap(pikawdt_private.fpga);
288 	return ret;
289 }
290 
pikawdt_exit(void)291 static void __exit pikawdt_exit(void)
292 {
293 	misc_deregister(&pikawdt_miscdev);
294 
295 	iounmap(pikawdt_private.fpga);
296 }
297 
298 module_init(pikawdt_init);
299 module_exit(pikawdt_exit);
300 
301 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
302 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
303 MODULE_LICENSE("GPL");
304