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1/*
2 * Watchdog driver for SiByte SB1 SoCs
3 *
4 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@lsi.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@lxorguk.ukuu.org.uk>,
39 * All Rights Reserved.
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
60static DEFINE_SPINLOCK(sbwd_lock);
61
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{
69 spin_lock(&sbwd_lock);
70 __raw_writeb(0, wdog);
71 __raw_writeq(t & 0x7fffffUL, wdog - 0x10);
72 spin_unlock(&sbwd_lock);
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 */
81void sbwdog_pet(char __iomem *wdog)
82{
83 spin_lock(&sbwd_lock);
84 __raw_writeb(__raw_readb(wdog) | 1, wdog);
85 spin_unlock(&sbwd_lock);
86}
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
94static const struct watchdog_info ident = {
95 .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
96 WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
97 .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);
106 if (test_and_set_bit(0, &sbwdog_gate))
107 return -EBUSY;
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 */
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 {
128 printk(KERN_CRIT
129 "%s: Unexpected close, not stopping watchdog!\n",
130 ident.identity);
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 */
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
156 if (get_user(c, data + i))
157 return -EFAULT;
158 if (c == 'V')
159 expect_close = 42;
160 }
161 sbwdog_pet(user_dog);
162 }
163
164 return len;
165}
166
167static long sbwdog_ioctl(struct file *file, unsigned int cmd,
168 unsigned long arg)
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
185 case WDIOC_KEEPALIVE:
186 sbwdog_pet(user_dog);
187 ret = 0;
188 break;
189
190 case WDIOC_SETTIMEOUT:
191 ret = get_user(time, p);
192 if (ret)
193 break;
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;
211 }
212 return ret;
213}
214
215/*
216 * Notifier for system down
217 */
218static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
219 void *erf)
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
232static const struct file_operations sbwdog_fops = {
233 .owner = THIS_MODULE,
234 .llseek = no_llseek,
235 .write = sbwdog_write,
236 .unlocked_ioctl = sbwdog_ioctl,
237 .open = sbwdog_open,
238 .release = sbwdog_release,
239};
240
241static struct miscdevice sbwdog_miscdev = {
242 .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 */
271 if (wd_cfg_reg == user_dog)
272 printk(KERN_CRIT "%s in danger of initiating system reset "
273 "in %ld.%01ld seconds\n",
274 ident.identity,
275 wd_init / 1000000, (wd_init / 100000) % 10);
276 else
277 cfg |= 1;
278
279 __raw_writeb(cfg, wd_cfg_reg);
280
281 return IRQ_HANDLED;
282}
283
284static int __init sbwdog_init(void)
285{
286 int ret;
287
288 /*
289 * register a reboot notifier
290 */
291 ret = register_reboot_notifier(&sbwdog_notifier);
292 if (ret) {
293 printk(KERN_ERR
294 "%s: cannot register reboot notifier (err=%d)\n",
295 ident.identity, ret);
296 return ret;
297 }
298
299 /*
300 * get the resources
301 */
302
303 ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
304 ident.identity, (void *)user_dog);
305 if (ret) {
306 printk(KERN_ERR "%s: failed to request irq 1 - %d\n",
307 ident.identity, ret);
308 goto out;
309 }
310
311 ret = misc_register(&sbwdog_miscdev);
312 if (ret == 0) {
313 printk(KERN_INFO "%s: timeout is %ld.%ld secs\n",
314 ident.identity,
315 timeout / 1000000, (timeout / 100000) % 10);
316 return 0;
317 }
318 free_irq(1, (void *)user_dog);
319out:
320 unregister_reboot_notifier(&sbwdog_notifier);
321
322 return ret;
323}
324
325static void __exit sbwdog_exit(void)
326{
327 misc_deregister(&sbwdog_miscdev);
328 free_irq(1, (void *)user_dog);
329 unregister_reboot_notifier(&sbwdog_notifier);
330}
331
332module_init(sbwdog_init);
333module_exit(sbwdog_exit);
334
335MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
336MODULE_DESCRIPTION("SiByte Watchdog");
337
338module_param(timeout, ulong, 0);
339MODULE_PARM_DESC(timeout,
340 "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
341
342MODULE_LICENSE("GPL");
343MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
344
345/*
346 * example code that can be put in a platform code area to utilize the
347 * first watchdog timer for the kernels own purpose.
348
349void platform_wd_setup(void)
350{
351 int ret;
352
353 ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
354 "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
355 if (ret) {
356 printk(KERN_CRIT
357 "Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
358 }
359}
360
361
362 */
1/*
2 * Watchdog driver for SiByte SB1 SoCs
3 *
4 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@lsi.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@lxorguk.ukuu.org.uk>,
39 * All Rights Reserved.
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
47#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
48
49#include <linux/module.h>
50#include <linux/io.h>
51#include <linux/uaccess.h>
52#include <linux/fs.h>
53#include <linux/reboot.h>
54#include <linux/miscdevice.h>
55#include <linux/watchdog.h>
56#include <linux/interrupt.h>
57
58#include <asm/sibyte/sb1250.h>
59#include <asm/sibyte/sb1250_regs.h>
60#include <asm/sibyte/sb1250_int.h>
61#include <asm/sibyte/sb1250_scd.h>
62
63static DEFINE_SPINLOCK(sbwd_lock);
64
65/*
66 * set the initial count value of a timer
67 *
68 * wdog is the iomem address of the cfg register
69 */
70void sbwdog_set(char __iomem *wdog, unsigned long t)
71{
72 spin_lock(&sbwd_lock);
73 __raw_writeb(0, wdog);
74 __raw_writeq(t & 0x7fffffUL, wdog - 0x10);
75 spin_unlock(&sbwd_lock);
76}
77
78/*
79 * cause the timer to [re]load it's initial count and start counting
80 * all over again
81 *
82 * wdog is the iomem address of the cfg register
83 */
84void sbwdog_pet(char __iomem *wdog)
85{
86 spin_lock(&sbwd_lock);
87 __raw_writeb(__raw_readb(wdog) | 1, wdog);
88 spin_unlock(&sbwd_lock);
89}
90
91static unsigned long sbwdog_gate; /* keeps it to one thread only */
92static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
93static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
94static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
95static int expect_close;
96
97static const struct watchdog_info ident = {
98 .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
99 WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
100 .identity = "SiByte Watchdog",
101};
102
103/*
104 * Allow only a single thread to walk the dog
105 */
106static int sbwdog_open(struct inode *inode, struct file *file)
107{
108 nonseekable_open(inode, file);
109 if (test_and_set_bit(0, &sbwdog_gate))
110 return -EBUSY;
111 __module_get(THIS_MODULE);
112
113 /*
114 * Activate the timer
115 */
116 sbwdog_set(user_dog, timeout);
117 __raw_writeb(1, user_dog);
118
119 return 0;
120}
121
122/*
123 * Put the dog back in the kennel.
124 */
125static int sbwdog_release(struct inode *inode, struct file *file)
126{
127 if (expect_close == 42) {
128 __raw_writeb(0, user_dog);
129 module_put(THIS_MODULE);
130 } else {
131 pr_crit("%s: Unexpected close, not stopping watchdog!\n",
132 ident.identity);
133 sbwdog_pet(user_dog);
134 }
135 clear_bit(0, &sbwdog_gate);
136 expect_close = 0;
137
138 return 0;
139}
140
141/*
142 * 42 - the answer
143 */
144static ssize_t sbwdog_write(struct file *file, const char __user *data,
145 size_t len, loff_t *ppos)
146{
147 int i;
148
149 if (len) {
150 /*
151 * restart the timer
152 */
153 expect_close = 0;
154
155 for (i = 0; i != len; i++) {
156 char c;
157
158 if (get_user(c, data + i))
159 return -EFAULT;
160 if (c == 'V')
161 expect_close = 42;
162 }
163 sbwdog_pet(user_dog);
164 }
165
166 return len;
167}
168
169static long sbwdog_ioctl(struct file *file, unsigned int cmd,
170 unsigned long arg)
171{
172 int ret = -ENOTTY;
173 unsigned long time;
174 void __user *argp = (void __user *)arg;
175 int __user *p = argp;
176
177 switch (cmd) {
178 case WDIOC_GETSUPPORT:
179 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
180 break;
181
182 case WDIOC_GETSTATUS:
183 case WDIOC_GETBOOTSTATUS:
184 ret = put_user(0, p);
185 break;
186
187 case WDIOC_KEEPALIVE:
188 sbwdog_pet(user_dog);
189 ret = 0;
190 break;
191
192 case WDIOC_SETTIMEOUT:
193 ret = get_user(time, p);
194 if (ret)
195 break;
196
197 time *= 1000000;
198 if (time > 0x7fffffUL) {
199 ret = -EINVAL;
200 break;
201 }
202 timeout = time;
203 sbwdog_set(user_dog, timeout);
204 sbwdog_pet(user_dog);
205
206 case WDIOC_GETTIMEOUT:
207 /*
208 * get the remaining count from the ... count register
209 * which is 1*8 before the config register
210 */
211 ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p);
212 break;
213 }
214 return ret;
215}
216
217/*
218 * Notifier for system down
219 */
220static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
221 void *erf)
222{
223 if (code == SYS_DOWN || code == SYS_HALT) {
224 /*
225 * sit and sit
226 */
227 __raw_writeb(0, user_dog);
228 __raw_writeb(0, kern_dog);
229 }
230
231 return NOTIFY_DONE;
232}
233
234static const struct file_operations sbwdog_fops = {
235 .owner = THIS_MODULE,
236 .llseek = no_llseek,
237 .write = sbwdog_write,
238 .unlocked_ioctl = sbwdog_ioctl,
239 .open = sbwdog_open,
240 .release = sbwdog_release,
241};
242
243static struct miscdevice sbwdog_miscdev = {
244 .minor = WATCHDOG_MINOR,
245 .name = "watchdog",
246 .fops = &sbwdog_fops,
247};
248
249static struct notifier_block sbwdog_notifier = {
250 .notifier_call = sbwdog_notify_sys,
251};
252
253/*
254 * interrupt handler
255 *
256 * doesn't do a whole lot for user, but oh so cleverly written so kernel
257 * code can use it to re-up the watchdog, thereby saving the kernel from
258 * having to create and maintain a timer, just to tickle another timer,
259 * which is just so wrong.
260 */
261irqreturn_t sbwdog_interrupt(int irq, void *addr)
262{
263 unsigned long wd_init;
264 char *wd_cfg_reg = (char *)addr;
265 u8 cfg;
266
267 cfg = __raw_readb(wd_cfg_reg);
268 wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
269
270 /*
271 * if it's the second watchdog timer, it's for those users
272 */
273 if (wd_cfg_reg == user_dog)
274 pr_crit("%s in danger of initiating system reset "
275 "in %ld.%01ld seconds\n",
276 ident.identity,
277 wd_init / 1000000, (wd_init / 100000) % 10);
278 else
279 cfg |= 1;
280
281 __raw_writeb(cfg, wd_cfg_reg);
282
283 return IRQ_HANDLED;
284}
285
286static int __init sbwdog_init(void)
287{
288 int ret;
289
290 /*
291 * register a reboot notifier
292 */
293 ret = register_reboot_notifier(&sbwdog_notifier);
294 if (ret) {
295 pr_err("%s: cannot register reboot notifier (err=%d)\n",
296 ident.identity, ret);
297 return ret;
298 }
299
300 /*
301 * get the resources
302 */
303
304 ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
305 ident.identity, (void *)user_dog);
306 if (ret) {
307 pr_err("%s: failed to request irq 1 - %d\n",
308 ident.identity, ret);
309 goto out;
310 }
311
312 ret = misc_register(&sbwdog_miscdev);
313 if (ret == 0) {
314 pr_info("%s: timeout is %ld.%ld secs\n",
315 ident.identity,
316 timeout / 1000000, (timeout / 100000) % 10);
317 return 0;
318 }
319 free_irq(1, (void *)user_dog);
320out:
321 unregister_reboot_notifier(&sbwdog_notifier);
322
323 return ret;
324}
325
326static void __exit sbwdog_exit(void)
327{
328 misc_deregister(&sbwdog_miscdev);
329 free_irq(1, (void *)user_dog);
330 unregister_reboot_notifier(&sbwdog_notifier);
331}
332
333module_init(sbwdog_init);
334module_exit(sbwdog_exit);
335
336MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
337MODULE_DESCRIPTION("SiByte Watchdog");
338
339module_param(timeout, ulong, 0);
340MODULE_PARM_DESC(timeout,
341 "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
342
343MODULE_LICENSE("GPL");
344
345/*
346 * example code that can be put in a platform code area to utilize the
347 * first watchdog timer for the kernels own purpose.
348
349void platform_wd_setup(void)
350{
351 int ret;
352
353 ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
354 "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
355 if (ret) {
356 pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
357 }
358}
359
360
361 */