xref: /openbmc/linux/drivers/watchdog/ar7_wdt.c (revision 4800cd83)
1 /*
2  * drivers/watchdog/ar7_wdt.c
3  *
4  * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
5  * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
6  *
7  * Some code taken from:
8  * National Semiconductor SCx200 Watchdog support
9  * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
24  */
25 
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/errno.h>
29 #include <linux/init.h>
30 #include <linux/miscdevice.h>
31 #include <linux/platform_device.h>
32 #include <linux/watchdog.h>
33 #include <linux/fs.h>
34 #include <linux/ioport.h>
35 #include <linux/io.h>
36 #include <linux/uaccess.h>
37 #include <linux/clk.h>
38 
39 #include <asm/addrspace.h>
40 #include <asm/mach-ar7/ar7.h>
41 
42 #define DRVNAME "ar7_wdt"
43 #define LONGNAME "TI AR7 Watchdog Timer"
44 
45 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
46 MODULE_DESCRIPTION(LONGNAME);
47 MODULE_LICENSE("GPL");
48 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
49 
50 static int margin = 60;
51 module_param(margin, int, 0);
52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
53 
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 module_param(nowayout, int, 0);
56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
57 
58 #define READ_REG(x) readl((void __iomem *)&(x))
59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
60 
61 struct ar7_wdt {
62 	u32 kick_lock;
63 	u32 kick;
64 	u32 change_lock;
65 	u32 change;
66 	u32 disable_lock;
67 	u32 disable;
68 	u32 prescale_lock;
69 	u32 prescale;
70 };
71 
72 static unsigned long wdt_is_open;
73 static spinlock_t wdt_lock;
74 static unsigned expect_close;
75 
76 /* XXX currently fixed, allows max margin ~68.72 secs */
77 #define prescale_value 0xffff
78 
79 /* Resource of the WDT registers */
80 static struct resource *ar7_regs_wdt;
81 /* Pointer to the remapped WDT IO space */
82 static struct ar7_wdt *ar7_wdt;
83 
84 static struct clk *vbus_clk;
85 
86 static void ar7_wdt_kick(u32 value)
87 {
88 	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
89 	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
90 		WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
91 		if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
92 			WRITE_REG(ar7_wdt->kick, value);
93 			return;
94 		}
95 	}
96 	printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
97 }
98 
99 static void ar7_wdt_prescale(u32 value)
100 {
101 	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
102 	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
103 		WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
104 		if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
105 			WRITE_REG(ar7_wdt->prescale, value);
106 			return;
107 		}
108 	}
109 	printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
110 }
111 
112 static void ar7_wdt_change(u32 value)
113 {
114 	WRITE_REG(ar7_wdt->change_lock, 0x6666);
115 	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
116 		WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
117 		if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
118 			WRITE_REG(ar7_wdt->change, value);
119 			return;
120 		}
121 	}
122 	printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
123 }
124 
125 static void ar7_wdt_disable(u32 value)
126 {
127 	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
128 	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
129 		WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
130 		if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
131 			WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
132 			if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
133 				WRITE_REG(ar7_wdt->disable, value);
134 				return;
135 			}
136 		}
137 	}
138 	printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
139 }
140 
141 static void ar7_wdt_update_margin(int new_margin)
142 {
143 	u32 change;
144 	u32 vbus_rate;
145 
146 	vbus_rate = clk_get_rate(vbus_clk);
147 	change = new_margin * (vbus_rate / prescale_value);
148 	if (change < 1)
149 		change = 1;
150 	if (change > 0xffff)
151 		change = 0xffff;
152 	ar7_wdt_change(change);
153 	margin = change * prescale_value / vbus_rate;
154 	printk(KERN_INFO DRVNAME
155 	       ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
156 	       margin, prescale_value, change, vbus_rate);
157 }
158 
159 static void ar7_wdt_enable_wdt(void)
160 {
161 	printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
162 	ar7_wdt_disable(1);
163 	ar7_wdt_kick(1);
164 }
165 
166 static void ar7_wdt_disable_wdt(void)
167 {
168 	printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
169 	ar7_wdt_disable(0);
170 }
171 
172 static int ar7_wdt_open(struct inode *inode, struct file *file)
173 {
174 	/* only allow one at a time */
175 	if (test_and_set_bit(0, &wdt_is_open))
176 		return -EBUSY;
177 	ar7_wdt_enable_wdt();
178 	expect_close = 0;
179 
180 	return nonseekable_open(inode, file);
181 }
182 
183 static int ar7_wdt_release(struct inode *inode, struct file *file)
184 {
185 	if (!expect_close)
186 		printk(KERN_WARNING DRVNAME
187 		": watchdog device closed unexpectedly,"
188 		"will not disable the watchdog timer\n");
189 	else if (!nowayout)
190 		ar7_wdt_disable_wdt();
191 	clear_bit(0, &wdt_is_open);
192 	return 0;
193 }
194 
195 static ssize_t ar7_wdt_write(struct file *file, const char *data,
196 			     size_t len, loff_t *ppos)
197 {
198 	/* check for a magic close character */
199 	if (len) {
200 		size_t i;
201 
202 		spin_lock(&wdt_lock);
203 		ar7_wdt_kick(1);
204 		spin_unlock(&wdt_lock);
205 
206 		expect_close = 0;
207 		for (i = 0; i < len; ++i) {
208 			char c;
209 			if (get_user(c, data + i))
210 				return -EFAULT;
211 			if (c == 'V')
212 				expect_close = 1;
213 		}
214 
215 	}
216 	return len;
217 }
218 
219 static long ar7_wdt_ioctl(struct file *file,
220 					unsigned int cmd, unsigned long arg)
221 {
222 	static const struct watchdog_info ident = {
223 		.identity = LONGNAME,
224 		.firmware_version = 1,
225 		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
226 						WDIOF_MAGICCLOSE),
227 	};
228 	int new_margin;
229 
230 	switch (cmd) {
231 	case WDIOC_GETSUPPORT:
232 		if (copy_to_user((struct watchdog_info *)arg, &ident,
233 				sizeof(ident)))
234 			return -EFAULT;
235 		return 0;
236 	case WDIOC_GETSTATUS:
237 	case WDIOC_GETBOOTSTATUS:
238 		if (put_user(0, (int *)arg))
239 			return -EFAULT;
240 		return 0;
241 	case WDIOC_KEEPALIVE:
242 		ar7_wdt_kick(1);
243 		return 0;
244 	case WDIOC_SETTIMEOUT:
245 		if (get_user(new_margin, (int *)arg))
246 			return -EFAULT;
247 		if (new_margin < 1)
248 			return -EINVAL;
249 
250 		spin_lock(&wdt_lock);
251 		ar7_wdt_update_margin(new_margin);
252 		ar7_wdt_kick(1);
253 		spin_unlock(&wdt_lock);
254 
255 	case WDIOC_GETTIMEOUT:
256 		if (put_user(margin, (int *)arg))
257 			return -EFAULT;
258 		return 0;
259 	default:
260 		return -ENOTTY;
261 	}
262 }
263 
264 static const struct file_operations ar7_wdt_fops = {
265 	.owner		= THIS_MODULE,
266 	.write		= ar7_wdt_write,
267 	.unlocked_ioctl	= ar7_wdt_ioctl,
268 	.open		= ar7_wdt_open,
269 	.release	= ar7_wdt_release,
270 	.llseek		= no_llseek,
271 };
272 
273 static struct miscdevice ar7_wdt_miscdev = {
274 	.minor		= WATCHDOG_MINOR,
275 	.name		= "watchdog",
276 	.fops		= &ar7_wdt_fops,
277 };
278 
279 static int __devinit ar7_wdt_probe(struct platform_device *pdev)
280 {
281 	int rc;
282 
283 	spin_lock_init(&wdt_lock);
284 
285 	ar7_regs_wdt =
286 		platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
287 	if (!ar7_regs_wdt) {
288 		printk(KERN_ERR DRVNAME ": could not get registers resource\n");
289 		rc = -ENODEV;
290 		goto out;
291 	}
292 
293 	if (!request_mem_region(ar7_regs_wdt->start,
294 				resource_size(ar7_regs_wdt), LONGNAME)) {
295 		printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
296 		rc = -EBUSY;
297 		goto out;
298 	}
299 
300 	ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
301 	if (!ar7_wdt) {
302 		printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
303 		rc = -ENXIO;
304 		goto out_mem_region;
305 	}
306 
307 	vbus_clk = clk_get(NULL, "vbus");
308 	if (IS_ERR(vbus_clk)) {
309 		printk(KERN_ERR DRVNAME ": could not get vbus clock\n");
310 		rc = PTR_ERR(vbus_clk);
311 		goto out_mem_region;
312 	}
313 
314 	ar7_wdt_disable_wdt();
315 	ar7_wdt_prescale(prescale_value);
316 	ar7_wdt_update_margin(margin);
317 
318 	rc = misc_register(&ar7_wdt_miscdev);
319 	if (rc) {
320 		printk(KERN_ERR DRVNAME ": unable to register misc device\n");
321 		goto out_alloc;
322 	}
323 	goto out;
324 
325 out_alloc:
326 	iounmap(ar7_wdt);
327 out_mem_region:
328 	release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
329 out:
330 	return rc;
331 }
332 
333 static int __devexit ar7_wdt_remove(struct platform_device *pdev)
334 {
335 	misc_deregister(&ar7_wdt_miscdev);
336 	iounmap(ar7_wdt);
337 	release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
338 
339 	return 0;
340 }
341 
342 static void ar7_wdt_shutdown(struct platform_device *pdev)
343 {
344 	if (!nowayout)
345 		ar7_wdt_disable_wdt();
346 }
347 
348 static struct platform_driver ar7_wdt_driver = {
349 	.probe = ar7_wdt_probe,
350 	.remove = __devexit_p(ar7_wdt_remove),
351 	.shutdown = ar7_wdt_shutdown,
352 	.driver = {
353 		.owner = THIS_MODULE,
354 		.name = "ar7_wdt",
355 	},
356 };
357 
358 static int __init ar7_wdt_init(void)
359 {
360 	return platform_driver_register(&ar7_wdt_driver);
361 }
362 
363 static void __exit ar7_wdt_cleanup(void)
364 {
365 	platform_driver_unregister(&ar7_wdt_driver);
366 }
367 
368 module_init(ar7_wdt_init);
369 module_exit(ar7_wdt_cleanup);
370