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 | * | |
29fa0586 AC |
38 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
39 | * All Rights Reserved. | |
75c752e6 AS |
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 | ||
df3c9de3 | 60 | static DEFINE_SPINLOCK(sbwd_lock); |
75c752e6 AS |
61 | |
62 | /* | |
63 | * set the initial count value of a timer | |
64 | * | |
65 | * wdog is the iomem address of the cfg register | |
66 | */ | |
67 | void sbwdog_set(char __iomem *wdog, unsigned long t) | |
68 | { | |
df3c9de3 | 69 | spin_lock(&sbwd_lock); |
75c752e6 AS |
70 | __raw_writeb(0, wdog - 0x10); |
71 | __raw_writeq(t & 0x7fffffUL, wdog); | |
df3c9de3 | 72 | spin_unlock(&sbwd_lock); |
75c752e6 AS |
73 | } |
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 | */ | |
81 | void sbwdog_pet(char __iomem *wdog) | |
82 | { | |
df3c9de3 | 83 | spin_lock(&sbwd_lock); |
75c752e6 | 84 | __raw_writeb(__raw_readb(wdog) | 1, wdog); |
df3c9de3 | 85 | spin_unlock(&sbwd_lock); |
75c752e6 AS |
86 | } |
87 | ||
88 | static unsigned long sbwdog_gate; /* keeps it to one thread only */ | |
89 | static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0)); | |
90 | static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1)); | |
91 | static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */ | |
92 | static int expect_close; | |
93 | ||
df3c9de3 AC |
94 | static const struct watchdog_info ident = { |
95 | .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | | |
96 | WDIOF_KEEPALIVEPING, | |
75c752e6 AS |
97 | .identity = "SiByte Watchdog", |
98 | }; | |
99 | ||
100 | /* | |
101 | * Allow only a single thread to walk the dog | |
102 | */ | |
103 | static int sbwdog_open(struct inode *inode, struct file *file) | |
104 | { | |
105 | nonseekable_open(inode, file); | |
df3c9de3 | 106 | if (test_and_set_bit(0, &sbwdog_gate)) |
75c752e6 | 107 | return -EBUSY; |
75c752e6 AS |
108 | __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 | */ | |
122 | static 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 { | |
df3c9de3 AC |
128 | printk(KERN_CRIT |
129 | "%s: Unexpected close, not stopping watchdog!\n", | |
130 | ident.identity); | |
75c752e6 AS |
131 | 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 | */ | |
142 | static 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 | ||
df3c9de3 | 156 | if (get_user(c, data + i)) |
75c752e6 | 157 | return -EFAULT; |
df3c9de3 | 158 | if (c == 'V') |
75c752e6 | 159 | expect_close = 42; |
75c752e6 AS |
160 | } |
161 | sbwdog_pet(user_dog); | |
162 | } | |
163 | ||
164 | return len; | |
165 | } | |
166 | ||
df3c9de3 AC |
167 | static long sbwdog_ioctl(struct file *file, unsigned int cmd, |
168 | unsigned long arg) | |
75c752e6 AS |
169 | { |
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 | ||
0c06090c WVS |
185 | case WDIOC_KEEPALIVE: |
186 | sbwdog_pet(user_dog); | |
187 | ret = 0; | |
188 | break; | |
189 | ||
75c752e6 AS |
190 | case WDIOC_SETTIMEOUT: |
191 | ret = get_user(time, p); | |
df3c9de3 | 192 | if (ret) |
75c752e6 | 193 | break; |
75c752e6 AS |
194 | |
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; | |
75c752e6 AS |
211 | } |
212 | return ret; | |
213 | } | |
214 | ||
215 | /* | |
216 | * Notifier for system down | |
217 | */ | |
7944d3a5 WVS |
218 | static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code, |
219 | void *erf) | |
75c752e6 AS |
220 | { |
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 | ||
df3c9de3 | 232 | static const struct file_operations sbwdog_fops = { |
75c752e6 AS |
233 | .owner = THIS_MODULE, |
234 | .llseek = no_llseek, | |
235 | .write = sbwdog_write, | |
df3c9de3 | 236 | .unlocked_ioctl = sbwdog_ioctl, |
75c752e6 AS |
237 | .open = sbwdog_open, |
238 | .release = sbwdog_release, | |
239 | }; | |
240 | ||
df3c9de3 | 241 | static struct miscdevice sbwdog_miscdev = { |
75c752e6 AS |
242 | .minor = WATCHDOG_MINOR, |
243 | .name = "watchdog", | |
244 | .fops = &sbwdog_fops, | |
245 | }; | |
246 | ||
247 | static 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 | */ | |
259 | irqreturn_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 | */ | |
df3c9de3 | 271 | if (wd_cfg_reg == user_dog) |
75c752e6 AS |
272 | 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); | |
df3c9de3 | 275 | else |
75c752e6 | 276 | cfg |= 1; |
75c752e6 AS |
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) { | |
df3c9de3 AC |
292 | printk(KERN_ERR |
293 | "%s: cannot register reboot notifier (err=%d)\n", | |
294 | ident.identity, ret); | |
75c752e6 AS |
295 | return ret; |
296 | } | |
297 | ||
298 | /* | |
299 | * get the resources | |
300 | */ | |
75c752e6 AS |
301 | |
302 | ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED, | |
303 | ident.identity, (void *)user_dog); | |
304 | if (ret) { | |
df3c9de3 AC |
305 | printk(KERN_ERR "%s: failed to request irq 1 - %d\n", |
306 | ident.identity, ret); | |
307 | return ret; | |
75c752e6 AS |
308 | } |
309 | ||
df3c9de3 AC |
310 | 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); | |
75c752e6 AS |
317 | return ret; |
318 | } | |
319 | ||
320 | static void __exit sbwdog_exit(void) | |
321 | { | |
322 | misc_deregister(&sbwdog_miscdev); | |
323 | } | |
324 | ||
325 | module_init(sbwdog_init); | |
326 | module_exit(sbwdog_exit); | |
327 | ||
328 | MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>"); | |
329 | MODULE_DESCRIPTION("SiByte Watchdog"); | |
330 | ||
331 | module_param(timeout, ulong, 0); | |
332 | MODULE_PARM_DESC(timeout, | |
df3c9de3 | 333 | "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)"); |
75c752e6 AS |
334 | |
335 | MODULE_LICENSE("GPL"); | |
336 | MODULE_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 | ||
df3c9de3 | 342 | void platform_wd_setup(void) |
75c752e6 AS |
343 | { |
344 | int ret; | |
345 | ||
df3c9de3 | 346 | ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED, |
75c752e6 AS |
347 | "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0)); |
348 | if (ret) { | |
df3c9de3 AC |
349 | printk(KERN_CRIT |
350 | "Watchdog IRQ zero(0) failed to be requested - %d\n", ret); | |
75c752e6 AS |
351 | } |
352 | } | |
353 | ||
354 | ||
355 | */ |