Commit | Line | Data |
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75c752e6 AS |
1 | /* |
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 | ||
60 | ||
61 | /* | |
62 | * set the initial count value of a timer | |
63 | * | |
64 | * wdog is the iomem address of the cfg register | |
65 | */ | |
66 | void sbwdog_set(char __iomem *wdog, unsigned long t) | |
67 | { | |
68 | __raw_writeb(0, wdog - 0x10); | |
69 | __raw_writeq(t & 0x7fffffUL, wdog); | |
70 | } | |
71 | ||
72 | /* | |
73 | * cause the timer to [re]load it's initial count and start counting | |
74 | * all over again | |
75 | * | |
76 | * wdog is the iomem address of the cfg register | |
77 | */ | |
78 | void sbwdog_pet(char __iomem *wdog) | |
79 | { | |
80 | __raw_writeb(__raw_readb(wdog) | 1, wdog); | |
81 | } | |
82 | ||
83 | static unsigned long sbwdog_gate; /* keeps it to one thread only */ | |
84 | static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0)); | |
85 | static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1)); | |
86 | static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */ | |
87 | static int expect_close; | |
88 | ||
89 | static struct watchdog_info ident = { | |
90 | .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, | |
91 | .identity = "SiByte Watchdog", | |
92 | }; | |
93 | ||
94 | /* | |
95 | * Allow only a single thread to walk the dog | |
96 | */ | |
97 | static int sbwdog_open(struct inode *inode, struct file *file) | |
98 | { | |
99 | nonseekable_open(inode, file); | |
100 | if (test_and_set_bit(0, &sbwdog_gate)) { | |
101 | return -EBUSY; | |
102 | } | |
103 | __module_get(THIS_MODULE); | |
104 | ||
105 | /* | |
106 | * Activate the timer | |
107 | */ | |
108 | sbwdog_set(user_dog, timeout); | |
109 | __raw_writeb(1, user_dog); | |
110 | ||
111 | return 0; | |
112 | } | |
113 | ||
114 | /* | |
115 | * Put the dog back in the kennel. | |
116 | */ | |
117 | static int sbwdog_release(struct inode *inode, struct file *file) | |
118 | { | |
119 | if (expect_close == 42) { | |
120 | __raw_writeb(0, user_dog); | |
121 | module_put(THIS_MODULE); | |
122 | } else { | |
123 | printk(KERN_CRIT "%s: Unexpected close, not stopping watchdog!\n", | |
124 | ident.identity); | |
125 | sbwdog_pet(user_dog); | |
126 | } | |
127 | clear_bit(0, &sbwdog_gate); | |
128 | expect_close = 0; | |
129 | ||
130 | return 0; | |
131 | } | |
132 | ||
133 | /* | |
134 | * 42 - the answer | |
135 | */ | |
136 | static ssize_t sbwdog_write(struct file *file, const char __user *data, | |
137 | size_t len, loff_t *ppos) | |
138 | { | |
139 | int i; | |
140 | ||
141 | if (len) { | |
142 | /* | |
143 | * restart the timer | |
144 | */ | |
145 | expect_close = 0; | |
146 | ||
147 | for (i = 0; i != len; i++) { | |
148 | char c; | |
149 | ||
150 | if (get_user(c, data + i)) { | |
151 | return -EFAULT; | |
152 | } | |
153 | if (c == 'V') { | |
154 | expect_close = 42; | |
155 | } | |
156 | } | |
157 | sbwdog_pet(user_dog); | |
158 | } | |
159 | ||
160 | return len; | |
161 | } | |
162 | ||
163 | static int sbwdog_ioctl(struct inode *inode, struct file *file, | |
164 | unsigned int cmd, unsigned long arg) | |
165 | { | |
166 | int ret = -ENOTTY; | |
167 | unsigned long time; | |
168 | void __user *argp = (void __user *)arg; | |
169 | int __user *p = argp; | |
170 | ||
171 | switch (cmd) { | |
172 | case WDIOC_GETSUPPORT: | |
173 | ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
174 | break; | |
175 | ||
176 | case WDIOC_GETSTATUS: | |
177 | case WDIOC_GETBOOTSTATUS: | |
178 | ret = put_user(0, p); | |
179 | break; | |
180 | ||
181 | case WDIOC_SETTIMEOUT: | |
182 | ret = get_user(time, p); | |
183 | if (ret) { | |
184 | break; | |
185 | } | |
186 | ||
187 | time *= 1000000; | |
188 | if (time > 0x7fffffUL) { | |
189 | ret = -EINVAL; | |
190 | break; | |
191 | } | |
192 | timeout = time; | |
193 | sbwdog_set(user_dog, timeout); | |
194 | sbwdog_pet(user_dog); | |
195 | ||
196 | case WDIOC_GETTIMEOUT: | |
197 | /* | |
198 | * get the remaining count from the ... count register | |
199 | * which is 1*8 before the config register | |
200 | */ | |
201 | ret = put_user(__raw_readq(user_dog - 8) / 1000000, p); | |
202 | break; | |
203 | ||
204 | case WDIOC_KEEPALIVE: | |
205 | sbwdog_pet(user_dog); | |
206 | ret = 0; | |
207 | break; | |
208 | } | |
209 | return ret; | |
210 | } | |
211 | ||
212 | /* | |
213 | * Notifier for system down | |
214 | */ | |
215 | static int | |
216 | sbwdog_notify_sys(struct notifier_block *this, unsigned long code, void *erf) | |
217 | { | |
218 | if (code == SYS_DOWN || code == SYS_HALT) { | |
219 | /* | |
220 | * sit and sit | |
221 | */ | |
222 | __raw_writeb(0, user_dog); | |
223 | __raw_writeb(0, kern_dog); | |
224 | } | |
225 | ||
226 | return NOTIFY_DONE; | |
227 | } | |
228 | ||
229 | static const struct file_operations sbwdog_fops = | |
230 | { | |
231 | .owner = THIS_MODULE, | |
232 | .llseek = no_llseek, | |
233 | .write = sbwdog_write, | |
234 | .ioctl = sbwdog_ioctl, | |
235 | .open = sbwdog_open, | |
236 | .release = sbwdog_release, | |
237 | }; | |
238 | ||
239 | static struct miscdevice sbwdog_miscdev = | |
240 | { | |
241 | .minor = WATCHDOG_MINOR, | |
242 | .name = "watchdog", | |
243 | .fops = &sbwdog_fops, | |
244 | }; | |
245 | ||
246 | static struct notifier_block sbwdog_notifier = { | |
247 | .notifier_call = sbwdog_notify_sys, | |
248 | }; | |
249 | ||
250 | /* | |
251 | * interrupt handler | |
252 | * | |
253 | * doesn't do a whole lot for user, but oh so cleverly written so kernel | |
254 | * code can use it to re-up the watchdog, thereby saving the kernel from | |
255 | * having to create and maintain a timer, just to tickle another timer, | |
256 | * which is just so wrong. | |
257 | */ | |
258 | irqreturn_t sbwdog_interrupt(int irq, void *addr) | |
259 | { | |
260 | unsigned long wd_init; | |
261 | char *wd_cfg_reg = (char *)addr; | |
262 | u8 cfg; | |
263 | ||
264 | cfg = __raw_readb(wd_cfg_reg); | |
265 | wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff; | |
266 | ||
267 | /* | |
268 | * if it's the second watchdog timer, it's for those users | |
269 | */ | |
270 | if (wd_cfg_reg == user_dog) { | |
271 | printk(KERN_CRIT | |
272 | "%s in danger of initiating system reset in %ld.%01ld seconds\n", | |
273 | ident.identity, wd_init / 1000000, (wd_init / 100000) % 10); | |
274 | } else { | |
275 | cfg |= 1; | |
276 | } | |
277 | ||
278 | __raw_writeb(cfg, wd_cfg_reg); | |
279 | ||
280 | return IRQ_HANDLED; | |
281 | } | |
282 | ||
283 | static 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) { | |
292 | printk (KERN_ERR "%s: cannot register reboot notifier (err=%d)\n", | |
293 | ident.identity, ret); | |
294 | return ret; | |
295 | } | |
296 | ||
297 | /* | |
298 | * get the resources | |
299 | */ | |
300 | ret = misc_register(&sbwdog_miscdev); | |
301 | if (ret == 0) { | |
302 | printk(KERN_INFO "%s: timeout is %ld.%ld secs\n", ident.identity, | |
303 | timeout / 1000000, (timeout / 100000) % 10); | |
304 | } | |
305 | ||
306 | ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED, | |
307 | ident.identity, (void *)user_dog); | |
308 | if (ret) { | |
309 | printk(KERN_ERR "%s: failed to request irq 1 - %d\n", ident.identity, | |
310 | ret); | |
311 | misc_deregister(&sbwdog_miscdev); | |
312 | } | |
313 | ||
314 | return ret; | |
315 | } | |
316 | ||
317 | static void __exit sbwdog_exit(void) | |
318 | { | |
319 | misc_deregister(&sbwdog_miscdev); | |
320 | } | |
321 | ||
322 | module_init(sbwdog_init); | |
323 | module_exit(sbwdog_exit); | |
324 | ||
325 | MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>"); | |
326 | MODULE_DESCRIPTION("SiByte Watchdog"); | |
327 | ||
328 | module_param(timeout, ulong, 0); | |
329 | MODULE_PARM_DESC(timeout, | |
330 | "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)"); | |
331 | ||
332 | MODULE_LICENSE("GPL"); | |
333 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
334 | ||
335 | /* | |
336 | * example code that can be put in a platform code area to utilize the | |
337 | * first watchdog timer for the kernels own purpose. | |
338 | ||
339 | void | |
340 | platform_wd_setup(void) | |
341 | { | |
342 | int ret; | |
343 | ||
344 | ret = request_irq(0, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED, | |
345 | "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0)); | |
346 | if (ret) { | |
347 | printk(KERN_CRIT "Watchdog IRQ zero(0) failed to be requested - %d\n", | |
348 | ret); | |
349 | } | |
350 | } | |
351 | ||
352 | ||
353 | */ |