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Andrew Sharp75c752e2007-12-13 16:16:42 -08001/*
2 * Watchdog driver for SiByte SB1 SoCs
3 *
4 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
5 *
6 * This driver is intended to make the second of two hardware watchdogs
7 * on the Sibyte 12XX and 11XX SoCs available to the user. There are two
8 * such devices available on the SoC, but it seems that there isn't an
9 * enumeration class for watchdogs in Linux like there is for RTCs.
10 * The second is used rather than the first because it uses IRQ 1,
11 * thereby avoiding all that IRQ 0 problematic nonsense.
12 *
13 * I have not tried this driver on a 1480 processor; it might work
14 * just well enough to really screw things up.
15 *
16 * It is a simple timer, and there is an interrupt that is raised the
17 * first time the timer expires. The second time it expires, the chip
18 * is reset and there is no way to redirect that NMI. Which could
19 * be problematic in some cases where this chip is sitting on the HT
20 * bus and has just taken responsibility for providing a cache block.
21 * Since the reset can't be redirected to the external reset pin, it is
22 * possible that other HT connected processors might hang and not reset.
23 * For Linux, a soft reset would probably be even worse than a hard reset.
24 * There you have it.
25 *
26 * The timer takes 23 bits of a 64 bit register (?) as a count value,
27 * and decrements the count every microsecond, for a max value of
28 * 0x7fffff usec or about 8.3ish seconds.
29 *
30 * This watchdog borrows some user semantics from the softdog driver,
31 * in that if you close the fd, it leaves the watchdog running, unless
32 * you previously wrote a 'V' to the fd, in which case it disables
33 * the watchdog when you close the fd like some other drivers.
34 *
35 * Based on various other watchdog drivers, which are probably all
36 * loosely based on something Alan Cox wrote years ago.
37 *
38 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
39 * http://www.redhat.com
40 *
41 * This program is free software; you can redistribute it and/or
42 * modify it under the terms of the GNU General Public License
43 * version 1 or 2 as published by the Free Software Foundation.
44 *
45 */
46#include <linux/module.h>
47#include <linux/io.h>
48#include <linux/uaccess.h>
49#include <linux/fs.h>
50#include <linux/reboot.h>
51#include <linux/miscdevice.h>
52#include <linux/watchdog.h>
53#include <linux/interrupt.h>
54
55#include <asm/sibyte/sb1250.h>
56#include <asm/sibyte/sb1250_regs.h>
57#include <asm/sibyte/sb1250_int.h>
58#include <asm/sibyte/sb1250_scd.h>
59
Alan Coxdf3c9de2008-05-19 14:08:33 +010060static DEFINE_SPINLOCK(sbwd_lock);
Andrew Sharp75c752e2007-12-13 16:16:42 -080061
62/*
63 * set the initial count value of a timer
64 *
65 * wdog is the iomem address of the cfg register
66 */
67void sbwdog_set(char __iomem *wdog, unsigned long t)
68{
Alan Coxdf3c9de2008-05-19 14:08:33 +010069 spin_lock(&sbwd_lock);
Andrew Sharp75c752e2007-12-13 16:16:42 -080070 __raw_writeb(0, wdog - 0x10);
71 __raw_writeq(t & 0x7fffffUL, wdog);
Alan Coxdf3c9de2008-05-19 14:08:33 +010072 spin_unlock(&sbwd_lock);
Andrew Sharp75c752e2007-12-13 16:16:42 -080073}
74
75/*
76 * cause the timer to [re]load it's initial count and start counting
77 * all over again
78 *
79 * wdog is the iomem address of the cfg register
80 */
81void sbwdog_pet(char __iomem *wdog)
82{
Alan Coxdf3c9de2008-05-19 14:08:33 +010083 spin_lock(&sbwd_lock);
Andrew Sharp75c752e2007-12-13 16:16:42 -080084 __raw_writeb(__raw_readb(wdog) | 1, wdog);
Alan Coxdf3c9de2008-05-19 14:08:33 +010085 spin_unlock(&sbwd_lock);
Andrew Sharp75c752e2007-12-13 16:16:42 -080086}
87
88static unsigned long sbwdog_gate; /* keeps it to one thread only */
89static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
90static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
91static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
92static int expect_close;
93
Alan Coxdf3c9de2008-05-19 14:08:33 +010094static const struct watchdog_info ident = {
95 .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
96 WDIOF_KEEPALIVEPING,
Andrew Sharp75c752e2007-12-13 16:16:42 -080097 .identity = "SiByte Watchdog",
98};
99
100/*
101 * Allow only a single thread to walk the dog
102 */
103static int sbwdog_open(struct inode *inode, struct file *file)
104{
105 nonseekable_open(inode, file);
Alan Coxdf3c9de2008-05-19 14:08:33 +0100106 if (test_and_set_bit(0, &sbwdog_gate))
Andrew Sharp75c752e2007-12-13 16:16:42 -0800107 return -EBUSY;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800108 __module_get(THIS_MODULE);
109
110 /*
111 * Activate the timer
112 */
113 sbwdog_set(user_dog, timeout);
114 __raw_writeb(1, user_dog);
115
116 return 0;
117}
118
119/*
120 * Put the dog back in the kennel.
121 */
122static int sbwdog_release(struct inode *inode, struct file *file)
123{
124 if (expect_close == 42) {
125 __raw_writeb(0, user_dog);
126 module_put(THIS_MODULE);
127 } else {
Alan Coxdf3c9de2008-05-19 14:08:33 +0100128 printk(KERN_CRIT
129 "%s: Unexpected close, not stopping watchdog!\n",
130 ident.identity);
Andrew Sharp75c752e2007-12-13 16:16:42 -0800131 sbwdog_pet(user_dog);
132 }
133 clear_bit(0, &sbwdog_gate);
134 expect_close = 0;
135
136 return 0;
137}
138
139/*
140 * 42 - the answer
141 */
142static ssize_t sbwdog_write(struct file *file, const char __user *data,
143 size_t len, loff_t *ppos)
144{
145 int i;
146
147 if (len) {
148 /*
149 * restart the timer
150 */
151 expect_close = 0;
152
153 for (i = 0; i != len; i++) {
154 char c;
155
Alan Coxdf3c9de2008-05-19 14:08:33 +0100156 if (get_user(c, data + i))
Andrew Sharp75c752e2007-12-13 16:16:42 -0800157 return -EFAULT;
Alan Coxdf3c9de2008-05-19 14:08:33 +0100158 if (c == 'V')
Andrew Sharp75c752e2007-12-13 16:16:42 -0800159 expect_close = 42;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800160 }
161 sbwdog_pet(user_dog);
162 }
163
164 return len;
165}
166
Alan Coxdf3c9de2008-05-19 14:08:33 +0100167static long sbwdog_ioctl(struct file *file, unsigned int cmd,
168 unsigned long arg)
Andrew Sharp75c752e2007-12-13 16:16:42 -0800169{
170 int ret = -ENOTTY;
171 unsigned long time;
172 void __user *argp = (void __user *)arg;
173 int __user *p = argp;
174
175 switch (cmd) {
176 case WDIOC_GETSUPPORT:
177 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
178 break;
179
180 case WDIOC_GETSTATUS:
181 case WDIOC_GETBOOTSTATUS:
182 ret = put_user(0, p);
183 break;
184
Wim Van Sebroeck0c060902008-07-18 11:41:17 +0000185 case WDIOC_KEEPALIVE:
186 sbwdog_pet(user_dog);
187 ret = 0;
188 break;
189
Andrew Sharp75c752e2007-12-13 16:16:42 -0800190 case WDIOC_SETTIMEOUT:
191 ret = get_user(time, p);
Alan Coxdf3c9de2008-05-19 14:08:33 +0100192 if (ret)
Andrew Sharp75c752e2007-12-13 16:16:42 -0800193 break;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800194
195 time *= 1000000;
196 if (time > 0x7fffffUL) {
197 ret = -EINVAL;
198 break;
199 }
200 timeout = time;
201 sbwdog_set(user_dog, timeout);
202 sbwdog_pet(user_dog);
203
204 case WDIOC_GETTIMEOUT:
205 /*
206 * get the remaining count from the ... count register
207 * which is 1*8 before the config register
208 */
209 ret = put_user(__raw_readq(user_dog - 8) / 1000000, p);
210 break;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800211 }
212 return ret;
213}
214
215/*
216 * Notifier for system down
217 */
Wim Van Sebroeck7944d3a2008-08-06 20:19:41 +0000218static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
219 void *erf)
Andrew Sharp75c752e2007-12-13 16:16:42 -0800220{
221 if (code == SYS_DOWN || code == SYS_HALT) {
222 /*
223 * sit and sit
224 */
225 __raw_writeb(0, user_dog);
226 __raw_writeb(0, kern_dog);
227 }
228
229 return NOTIFY_DONE;
230}
231
Alan Coxdf3c9de2008-05-19 14:08:33 +0100232static const struct file_operations sbwdog_fops = {
Andrew Sharp75c752e2007-12-13 16:16:42 -0800233 .owner = THIS_MODULE,
234 .llseek = no_llseek,
235 .write = sbwdog_write,
Alan Coxdf3c9de2008-05-19 14:08:33 +0100236 .unlocked_ioctl = sbwdog_ioctl,
Andrew Sharp75c752e2007-12-13 16:16:42 -0800237 .open = sbwdog_open,
238 .release = sbwdog_release,
239};
240
Alan Coxdf3c9de2008-05-19 14:08:33 +0100241static struct miscdevice sbwdog_miscdev = {
Andrew Sharp75c752e2007-12-13 16:16:42 -0800242 .minor = WATCHDOG_MINOR,
243 .name = "watchdog",
244 .fops = &sbwdog_fops,
245};
246
247static struct notifier_block sbwdog_notifier = {
248 .notifier_call = sbwdog_notify_sys,
249};
250
251/*
252 * interrupt handler
253 *
254 * doesn't do a whole lot for user, but oh so cleverly written so kernel
255 * code can use it to re-up the watchdog, thereby saving the kernel from
256 * having to create and maintain a timer, just to tickle another timer,
257 * which is just so wrong.
258 */
259irqreturn_t sbwdog_interrupt(int irq, void *addr)
260{
261 unsigned long wd_init;
262 char *wd_cfg_reg = (char *)addr;
263 u8 cfg;
264
265 cfg = __raw_readb(wd_cfg_reg);
266 wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
267
268 /*
269 * if it's the second watchdog timer, it's for those users
270 */
Alan Coxdf3c9de2008-05-19 14:08:33 +0100271 if (wd_cfg_reg == user_dog)
Andrew Sharp75c752e2007-12-13 16:16:42 -0800272 printk(KERN_CRIT
273 "%s in danger of initiating system reset in %ld.%01ld seconds\n",
274 ident.identity, wd_init / 1000000, (wd_init / 100000) % 10);
Alan Coxdf3c9de2008-05-19 14:08:33 +0100275 else
Andrew Sharp75c752e2007-12-13 16:16:42 -0800276 cfg |= 1;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800277
278 __raw_writeb(cfg, wd_cfg_reg);
279
280 return IRQ_HANDLED;
281}
282
283static int __init sbwdog_init(void)
284{
285 int ret;
286
287 /*
288 * register a reboot notifier
289 */
290 ret = register_reboot_notifier(&sbwdog_notifier);
291 if (ret) {
Alan Coxdf3c9de2008-05-19 14:08:33 +0100292 printk(KERN_ERR
293 "%s: cannot register reboot notifier (err=%d)\n",
294 ident.identity, ret);
Andrew Sharp75c752e2007-12-13 16:16:42 -0800295 return ret;
296 }
297
298 /*
299 * get the resources
300 */
Andrew Sharp75c752e2007-12-13 16:16:42 -0800301
302 ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
303 ident.identity, (void *)user_dog);
304 if (ret) {
Alan Coxdf3c9de2008-05-19 14:08:33 +0100305 printk(KERN_ERR "%s: failed to request irq 1 - %d\n",
306 ident.identity, ret);
307 return ret;
Andrew Sharp75c752e2007-12-13 16:16:42 -0800308 }
309
Alan Coxdf3c9de2008-05-19 14:08:33 +0100310 ret = misc_register(&sbwdog_miscdev);
311 if (ret == 0) {
312 printk(KERN_INFO "%s: timeout is %ld.%ld secs\n",
313 ident.identity,
314 timeout / 1000000, (timeout / 100000) % 10);
315 } else
316 free_irq(1, (void *)user_dog);
Andrew Sharp75c752e2007-12-13 16:16:42 -0800317 return ret;
318}
319
320static void __exit sbwdog_exit(void)
321{
322 misc_deregister(&sbwdog_miscdev);
323}
324
325module_init(sbwdog_init);
326module_exit(sbwdog_exit);
327
328MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>");
329MODULE_DESCRIPTION("SiByte Watchdog");
330
331module_param(timeout, ulong, 0);
332MODULE_PARM_DESC(timeout,
Alan Coxdf3c9de2008-05-19 14:08:33 +0100333 "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
Andrew Sharp75c752e2007-12-13 16:16:42 -0800334
335MODULE_LICENSE("GPL");
336MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
337
338/*
339 * example code that can be put in a platform code area to utilize the
340 * first watchdog timer for the kernels own purpose.
341
Alan Coxdf3c9de2008-05-19 14:08:33 +0100342void platform_wd_setup(void)
Andrew Sharp75c752e2007-12-13 16:16:42 -0800343{
344 int ret;
345
Alan Coxdf3c9de2008-05-19 14:08:33 +0100346 ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
Andrew Sharp75c752e2007-12-13 16:16:42 -0800347 "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
348 if (ret) {
Alan Coxdf3c9de2008-05-19 14:08:33 +0100349 printk(KERN_CRIT
350 "Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
Andrew Sharp75c752e2007-12-13 16:16:42 -0800351 }
352}
353
354
355 */