xref: /linux/drivers/watchdog/rc32434_wdt.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478) 
1 /*
2  *  IDT Interprise 79RC32434 watchdog driver
3  *
4  *  Copyright (C) 2006, Ondrej Zajicek <santiago@crfreenet.org>
5  *  Copyright (C) 2008, Florian Fainelli <florian@openwrt.org>
6  *
7  *  based on
8  *  SoftDog 0.05:	A Software Watchdog Device
9  *
10  *  (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
11  *					All Rights Reserved.
12  *
13  *  This program is free software; you can redistribute it and/or
14  *  modify it under the terms of the GNU General Public License
15  *  as published by the Free Software Foundation; either version
16  *  2 of the License, or (at your option) any later version.
17  *
18  */
19 
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 
22 #include <linux/module.h>		/* For module specific items */
23 #include <linux/moduleparam.h>		/* For new moduleparam's */
24 #include <linux/types.h>		/* For standard types (like size_t) */
25 #include <linux/errno.h>		/* For the -ENODEV/... values */
26 #include <linux/kernel.h>		/* For printk/panic/... */
27 #include <linux/fs.h>			/* For file operations */
28 #include <linux/miscdevice.h>		/* For MODULE_ALIAS_MISCDEV
29 							(WATCHDOG_MINOR) */
30 #include <linux/watchdog.h>		/* For the watchdog specific items */
31 #include <linux/init.h>			/* For __init/__exit/... */
32 #include <linux/platform_device.h>	/* For platform_driver framework */
33 #include <linux/spinlock.h>		/* For spin_lock/spin_unlock/... */
34 #include <linux/uaccess.h>		/* For copy_to_user/put_user/... */
35 
36 #include <asm/mach-rc32434/integ.h>	/* For the Watchdog registers */
37 
38 #define VERSION "1.0"
39 
40 static struct {
41 	unsigned long inuse;
42 	spinlock_t io_lock;
43 } rc32434_wdt_device;
44 
45 static struct integ __iomem *wdt_reg;
46 
47 static int expect_close;
48 
49 /* Board internal clock speed in Hz,
50  * the watchdog timer ticks at. */
51 extern unsigned int idt_cpu_freq;
52 
53 /* translate wtcompare value to seconds and vice versa */
54 #define WTCOMP2SEC(x)	(x / idt_cpu_freq)
55 #define SEC2WTCOMP(x)	(x * idt_cpu_freq)
56 
57 /* Use a default timeout of 20s. This should be
58  * safe for CPU clock speeds up to 400MHz, as
59  * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
60 #define WATCHDOG_TIMEOUT 20
61 
62 static int timeout = WATCHDOG_TIMEOUT;
63 module_param(timeout, int, 0);
64 MODULE_PARM_DESC(timeout, "Watchdog timeout value, in seconds (default="
65 		__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
66 
67 static bool nowayout = WATCHDOG_NOWAYOUT;
68 module_param(nowayout, bool, 0);
69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
70 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
71 
72 /* apply or and nand masks to data read from addr and write back */
73 #define SET_BITS(addr, or, nand) \
74 	writel((readl(&addr) | or) & ~nand, &addr)
75 
76 static int rc32434_wdt_set(int new_timeout)
77 {
78 	int max_to = WTCOMP2SEC((u32)-1);
79 
80 	if (new_timeout < 0 || new_timeout > max_to) {
81 		pr_err("timeout value must be between 0 and %d\n", max_to);
82 		return -EINVAL;
83 	}
84 	timeout = new_timeout;
85 	spin_lock(&rc32434_wdt_device.io_lock);
86 	writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
87 	spin_unlock(&rc32434_wdt_device.io_lock);
88 
89 	return 0;
90 }
91 
92 static void rc32434_wdt_start(void)
93 {
94 	u32 or, nand;
95 
96 	spin_lock(&rc32434_wdt_device.io_lock);
97 
98 	/* zero the counter before enabling */
99 	writel(0, &wdt_reg->wtcount);
100 
101 	/* don't generate a non-maskable interrupt,
102 	 * do a warm reset instead */
103 	nand = 1 << RC32434_ERR_WNE;
104 	or = 1 << RC32434_ERR_WRE;
105 
106 	/* reset the ERRCS timeout bit in case it's set */
107 	nand |= 1 << RC32434_ERR_WTO;
108 
109 	SET_BITS(wdt_reg->errcs, or, nand);
110 
111 	/* set the timeout (either default or based on module param) */
112 	rc32434_wdt_set(timeout);
113 
114 	/* reset WTC timeout bit and enable WDT */
115 	nand = 1 << RC32434_WTC_TO;
116 	or = 1 << RC32434_WTC_EN;
117 
118 	SET_BITS(wdt_reg->wtc, or, nand);
119 
120 	spin_unlock(&rc32434_wdt_device.io_lock);
121 	pr_info("Started watchdog timer\n");
122 }
123 
124 static void rc32434_wdt_stop(void)
125 {
126 	spin_lock(&rc32434_wdt_device.io_lock);
127 
128 	/* Disable WDT */
129 	SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
130 
131 	spin_unlock(&rc32434_wdt_device.io_lock);
132 	pr_info("Stopped watchdog timer\n");
133 }
134 
135 static void rc32434_wdt_ping(void)
136 {
137 	spin_lock(&rc32434_wdt_device.io_lock);
138 	writel(0, &wdt_reg->wtcount);
139 	spin_unlock(&rc32434_wdt_device.io_lock);
140 }
141 
142 static int rc32434_wdt_open(struct inode *inode, struct file *file)
143 {
144 	if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
145 		return -EBUSY;
146 
147 	if (nowayout)
148 		__module_get(THIS_MODULE);
149 
150 	rc32434_wdt_start();
151 	rc32434_wdt_ping();
152 
153 	return nonseekable_open(inode, file);
154 }
155 
156 static int rc32434_wdt_release(struct inode *inode, struct file *file)
157 {
158 	if (expect_close == 42) {
159 		rc32434_wdt_stop();
160 		module_put(THIS_MODULE);
161 	} else {
162 		pr_crit("device closed unexpectedly. WDT will not stop!\n");
163 		rc32434_wdt_ping();
164 	}
165 	clear_bit(0, &rc32434_wdt_device.inuse);
166 	return 0;
167 }
168 
169 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
170 				size_t len, loff_t *ppos)
171 {
172 	if (len) {
173 		if (!nowayout) {
174 			size_t i;
175 
176 			/* In case it was set long ago */
177 			expect_close = 0;
178 
179 			for (i = 0; i != len; i++) {
180 				char c;
181 				if (get_user(c, data + i))
182 					return -EFAULT;
183 				if (c == 'V')
184 					expect_close = 42;
185 			}
186 		}
187 		rc32434_wdt_ping();
188 		return len;
189 	}
190 	return 0;
191 }
192 
193 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
194 				unsigned long arg)
195 {
196 	void __user *argp = (void __user *)arg;
197 	int new_timeout;
198 	unsigned int value;
199 	static const struct watchdog_info ident = {
200 		.options =		WDIOF_SETTIMEOUT |
201 					WDIOF_KEEPALIVEPING |
202 					WDIOF_MAGICCLOSE,
203 		.identity =		"RC32434_WDT Watchdog",
204 	};
205 	switch (cmd) {
206 	case WDIOC_GETSUPPORT:
207 		if (copy_to_user(argp, &ident, sizeof(ident)))
208 			return -EFAULT;
209 		break;
210 	case WDIOC_GETSTATUS:
211 	case WDIOC_GETBOOTSTATUS:
212 		value = 0;
213 		if (copy_to_user(argp, &value, sizeof(int)))
214 			return -EFAULT;
215 		break;
216 	case WDIOC_SETOPTIONS:
217 		if (copy_from_user(&value, argp, sizeof(int)))
218 			return -EFAULT;
219 		switch (value) {
220 		case WDIOS_ENABLECARD:
221 			rc32434_wdt_start();
222 			break;
223 		case WDIOS_DISABLECARD:
224 			rc32434_wdt_stop();
225 			break;
226 		default:
227 			return -EINVAL;
228 		}
229 		break;
230 	case WDIOC_KEEPALIVE:
231 		rc32434_wdt_ping();
232 		break;
233 	case WDIOC_SETTIMEOUT:
234 		if (copy_from_user(&new_timeout, argp, sizeof(int)))
235 			return -EFAULT;
236 		if (rc32434_wdt_set(new_timeout))
237 			return -EINVAL;
238 		/* Fall through */
239 	case WDIOC_GETTIMEOUT:
240 		return copy_to_user(argp, &timeout, sizeof(int));
241 	default:
242 		return -ENOTTY;
243 	}
244 
245 	return 0;
246 }
247 
248 static const struct file_operations rc32434_wdt_fops = {
249 	.owner		= THIS_MODULE,
250 	.llseek		= no_llseek,
251 	.write		= rc32434_wdt_write,
252 	.unlocked_ioctl	= rc32434_wdt_ioctl,
253 	.open		= rc32434_wdt_open,
254 	.release	= rc32434_wdt_release,
255 };
256 
257 static struct miscdevice rc32434_wdt_miscdev = {
258 	.minor	= WATCHDOG_MINOR,
259 	.name	= "watchdog",
260 	.fops	= &rc32434_wdt_fops,
261 };
262 
263 static int rc32434_wdt_probe(struct platform_device *pdev)
264 {
265 	int ret;
266 	struct resource *r;
267 
268 	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
269 	if (!r) {
270 		pr_err("failed to retrieve resources\n");
271 		return -ENODEV;
272 	}
273 
274 	wdt_reg = ioremap_nocache(r->start, resource_size(r));
275 	if (!wdt_reg) {
276 		pr_err("failed to remap I/O resources\n");
277 		return -ENXIO;
278 	}
279 
280 	spin_lock_init(&rc32434_wdt_device.io_lock);
281 
282 	/* Make sure the watchdog is not running */
283 	rc32434_wdt_stop();
284 
285 	/* Check that the heartbeat value is within it's range;
286 	 * if not reset to the default */
287 	if (rc32434_wdt_set(timeout)) {
288 		rc32434_wdt_set(WATCHDOG_TIMEOUT);
289 		pr_info("timeout value must be between 0 and %d\n",
290 			WTCOMP2SEC((u32)-1));
291 	}
292 
293 	ret = misc_register(&rc32434_wdt_miscdev);
294 	if (ret < 0) {
295 		pr_err("failed to register watchdog device\n");
296 		goto unmap;
297 	}
298 
299 	pr_info("Watchdog Timer version " VERSION ", timer margin: %d sec\n",
300 		timeout);
301 
302 	return 0;
303 
304 unmap:
305 	iounmap(wdt_reg);
306 	return ret;
307 }
308 
309 static int rc32434_wdt_remove(struct platform_device *pdev)
310 {
311 	misc_deregister(&rc32434_wdt_miscdev);
312 	iounmap(wdt_reg);
313 	return 0;
314 }
315 
316 static void rc32434_wdt_shutdown(struct platform_device *pdev)
317 {
318 	rc32434_wdt_stop();
319 }
320 
321 static struct platform_driver rc32434_wdt_driver = {
322 	.probe		= rc32434_wdt_probe,
323 	.remove		= rc32434_wdt_remove,
324 	.shutdown	= rc32434_wdt_shutdown,
325 	.driver		= {
326 			.name = "rc32434_wdt",
327 	}
328 };
329 
330 module_platform_driver(rc32434_wdt_driver);
331 
332 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
333 		"Florian Fainelli <florian@openwrt.org>");
334 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
335 MODULE_LICENSE("GPL");
336 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
337