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 #include <linux/module.h>		/* For module specific items */
21 #include <linux/moduleparam.h>		/* For new moduleparam's */
22 #include <linux/types.h>		/* For standard types (like size_t) */
23 #include <linux/errno.h>		/* For the -ENODEV/... values */
24 #include <linux/kernel.h>		/* For printk/panic/... */
25 #include <linux/fs.h>			/* For file operations */
26 #include <linux/miscdevice.h>		/* For MODULE_ALIAS_MISCDEV
27 							(WATCHDOG_MINOR) */
28 #include <linux/watchdog.h>		/* For the watchdog specific items */
29 #include <linux/init.h>			/* For __init/__exit/... */
30 #include <linux/platform_device.h>	/* For platform_driver framework */
31 #include <linux/spinlock.h>		/* For spin_lock/spin_unlock/... */
32 #include <linux/uaccess.h>		/* For copy_to_user/put_user/... */
33 
34 #include <asm/mach-rc32434/integ.h>	/* For the Watchdog registers */
35 
36 #define PFX KBUILD_MODNAME ": "
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 int nowayout = WATCHDOG_NOWAYOUT;
68 module_param(nowayout, int, 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 		printk(KERN_ERR PFX "timeout value must be between 0 and %d",
82 			max_to);
83 		return -EINVAL;
84 	}
85 	timeout = new_timeout;
86 	spin_lock(&rc32434_wdt_device.io_lock);
87 	writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
88 	spin_unlock(&rc32434_wdt_device.io_lock);
89 
90 	return 0;
91 }
92 
93 static void rc32434_wdt_start(void)
94 {
95 	u32 or, nand;
96 
97 	spin_lock(&rc32434_wdt_device.io_lock);
98 
99 	/* zero the counter before enabling */
100 	writel(0, &wdt_reg->wtcount);
101 
102 	/* don't generate a non-maskable interrupt,
103 	 * do a warm reset instead */
104 	nand = 1 << RC32434_ERR_WNE;
105 	or = 1 << RC32434_ERR_WRE;
106 
107 	/* reset the ERRCS timeout bit in case it's set */
108 	nand |= 1 << RC32434_ERR_WTO;
109 
110 	SET_BITS(wdt_reg->errcs, or, nand);
111 
112 	/* set the timeout (either default or based on module param) */
113 	rc32434_wdt_set(timeout);
114 
115 	/* reset WTC timeout bit and enable WDT */
116 	nand = 1 << RC32434_WTC_TO;
117 	or = 1 << RC32434_WTC_EN;
118 
119 	SET_BITS(wdt_reg->wtc, or, nand);
120 
121 	spin_unlock(&rc32434_wdt_device.io_lock);
122 	printk(KERN_INFO PFX "Started watchdog timer.\n");
123 }
124 
125 static void rc32434_wdt_stop(void)
126 {
127 	spin_lock(&rc32434_wdt_device.io_lock);
128 
129 	/* Disable WDT */
130 	SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
131 
132 	spin_unlock(&rc32434_wdt_device.io_lock);
133 	printk(KERN_INFO PFX "Stopped watchdog timer.\n");
134 }
135 
136 static void rc32434_wdt_ping(void)
137 {
138 	spin_lock(&rc32434_wdt_device.io_lock);
139 	writel(0, &wdt_reg->wtcount);
140 	spin_unlock(&rc32434_wdt_device.io_lock);
141 }
142 
143 static int rc32434_wdt_open(struct inode *inode, struct file *file)
144 {
145 	if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
146 		return -EBUSY;
147 
148 	if (nowayout)
149 		__module_get(THIS_MODULE);
150 
151 	rc32434_wdt_start();
152 	rc32434_wdt_ping();
153 
154 	return nonseekable_open(inode, file);
155 }
156 
157 static int rc32434_wdt_release(struct inode *inode, struct file *file)
158 {
159 	if (expect_close == 42) {
160 		rc32434_wdt_stop();
161 		module_put(THIS_MODULE);
162 	} else {
163 		printk(KERN_CRIT PFX
164 			"device closed unexpectedly. WDT will not stop!\n");
165 		rc32434_wdt_ping();
166 	}
167 	clear_bit(0, &rc32434_wdt_device.inuse);
168 	return 0;
169 }
170 
171 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
172 				size_t len, loff_t *ppos)
173 {
174 	if (len) {
175 		if (!nowayout) {
176 			size_t i;
177 
178 			/* In case it was set long ago */
179 			expect_close = 0;
180 
181 			for (i = 0; i != len; i++) {
182 				char c;
183 				if (get_user(c, data + i))
184 					return -EFAULT;
185 				if (c == 'V')
186 					expect_close = 42;
187 			}
188 		}
189 		rc32434_wdt_ping();
190 		return len;
191 	}
192 	return 0;
193 }
194 
195 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
196 				unsigned long arg)
197 {
198 	void __user *argp = (void __user *)arg;
199 	int new_timeout;
200 	unsigned int value;
201 	static const struct watchdog_info ident = {
202 		.options =		WDIOF_SETTIMEOUT |
203 					WDIOF_KEEPALIVEPING |
204 					WDIOF_MAGICCLOSE,
205 		.identity =		"RC32434_WDT Watchdog",
206 	};
207 	switch (cmd) {
208 	case WDIOC_GETSUPPORT:
209 		if (copy_to_user(argp, &ident, sizeof(ident)))
210 			return -EFAULT;
211 		break;
212 	case WDIOC_GETSTATUS:
213 	case WDIOC_GETBOOTSTATUS:
214 		value = 0;
215 		if (copy_to_user(argp, &value, sizeof(int)))
216 			return -EFAULT;
217 		break;
218 	case WDIOC_SETOPTIONS:
219 		if (copy_from_user(&value, argp, sizeof(int)))
220 			return -EFAULT;
221 		switch (value) {
222 		case WDIOS_ENABLECARD:
223 			rc32434_wdt_start();
224 			break;
225 		case WDIOS_DISABLECARD:
226 			rc32434_wdt_stop();
227 			break;
228 		default:
229 			return -EINVAL;
230 		}
231 		break;
232 	case WDIOC_KEEPALIVE:
233 		rc32434_wdt_ping();
234 		break;
235 	case WDIOC_SETTIMEOUT:
236 		if (copy_from_user(&new_timeout, argp, sizeof(int)))
237 			return -EFAULT;
238 		if (rc32434_wdt_set(new_timeout))
239 			return -EINVAL;
240 		/* Fall through */
241 	case WDIOC_GETTIMEOUT:
242 		return copy_to_user(argp, &timeout, sizeof(int));
243 	default:
244 		return -ENOTTY;
245 	}
246 
247 	return 0;
248 }
249 
250 static const struct file_operations rc32434_wdt_fops = {
251 	.owner		= THIS_MODULE,
252 	.llseek		= no_llseek,
253 	.write		= rc32434_wdt_write,
254 	.unlocked_ioctl	= rc32434_wdt_ioctl,
255 	.open		= rc32434_wdt_open,
256 	.release	= rc32434_wdt_release,
257 };
258 
259 static struct miscdevice rc32434_wdt_miscdev = {
260 	.minor	= WATCHDOG_MINOR,
261 	.name	= "watchdog",
262 	.fops	= &rc32434_wdt_fops,
263 };
264 
265 static char banner[] __devinitdata = KERN_INFO PFX
266 		"Watchdog Timer version " VERSION ", timer margin: %d sec\n";
267 
268 static int __devinit rc32434_wdt_probe(struct platform_device *pdev)
269 {
270 	int ret;
271 	struct resource *r;
272 
273 	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
274 	if (!r) {
275 		printk(KERN_ERR PFX "failed to retrieve resources\n");
276 		return -ENODEV;
277 	}
278 
279 	wdt_reg = ioremap_nocache(r->start, resource_size(r));
280 	if (!wdt_reg) {
281 		printk(KERN_ERR PFX "failed to remap I/O resources\n");
282 		return -ENXIO;
283 	}
284 
285 	spin_lock_init(&rc32434_wdt_device.io_lock);
286 
287 	/* Make sure the watchdog is not running */
288 	rc32434_wdt_stop();
289 
290 	/* Check that the heartbeat value is within it's range;
291 	 * if not reset to the default */
292 	if (rc32434_wdt_set(timeout)) {
293 		rc32434_wdt_set(WATCHDOG_TIMEOUT);
294 		printk(KERN_INFO PFX
295 			"timeout value must be between 0 and %d\n",
296 			WTCOMP2SEC((u32)-1));
297 	}
298 
299 	ret = misc_register(&rc32434_wdt_miscdev);
300 	if (ret < 0) {
301 		printk(KERN_ERR PFX "failed to register watchdog device\n");
302 		goto unmap;
303 	}
304 
305 	printk(banner, timeout);
306 
307 	return 0;
308 
309 unmap:
310 	iounmap(wdt_reg);
311 	return ret;
312 }
313 
314 static int __devexit rc32434_wdt_remove(struct platform_device *pdev)
315 {
316 	misc_deregister(&rc32434_wdt_miscdev);
317 	iounmap(wdt_reg);
318 	return 0;
319 }
320 
321 static void rc32434_wdt_shutdown(struct platform_device *pdev)
322 {
323 	rc32434_wdt_stop();
324 }
325 
326 static struct platform_driver rc32434_wdt_driver = {
327 	.probe		= rc32434_wdt_probe,
328 	.remove		= __devexit_p(rc32434_wdt_remove),
329 	.shutdown	= rc32434_wdt_shutdown,
330 	.driver		= {
331 			.name = "rc32434_wdt",
332 	}
333 };
334 
335 module_platform_driver(rc32434_wdt_driver);
336 
337 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
338 		"Florian Fainelli <florian@openwrt.org>");
339 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
340 MODULE_LICENSE("GPL");
341 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
342