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1 | /* |
2 | * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface |
3 | * |
4 | * Authors: Dave Updegraff <dave@cray.org> |
5 | * Kumar Gala <galak@kernel.crashing.org> |
6 | * Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org> |
7 | * ..and from sc520_wdt |
8 | * Copyright (c) 2008 MontaVista Software, Inc. |
9 | * Anton Vorontsov <avorontsov@ru.mvista.com> |
10 | * |
11 | * Note: it appears that you can only actually ENABLE or DISABLE the thing |
12 | * once after POR. Once enabled, you cannot disable, and vice versa. |
13 | * |
14 | * This program is free software; you can redistribute it and/or modify it |
15 | * under the terms of the GNU General Public License as published by the |
16 | * Free Software Foundation; either version 2 of the License, or (at your |
17 | * option) any later version. |
18 | */ |
19 | |
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
21 | |
22 | #include <linux/fs.h> |
23 | #include <linux/init.h> |
24 | #include <linux/kernel.h> |
25 | #include <linux/timer.h> |
26 | #include <linux/miscdevice.h> |
27 | #include <linux/of_platform.h> |
28 | #include <linux/module.h> |
29 | #include <linux/watchdog.h> |
30 | #include <linux/io.h> |
31 | #include <linux/uaccess.h> |
32 | #include <sysdev/fsl_soc.h> |
33 | |
34 | struct mpc8xxx_wdt { |
35 | __be32 res0; |
36 | __be32 swcrr; /* System watchdog control register */ |
37 | #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */ |
38 | #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */ |
39 | #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/ |
40 | #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */ |
41 | __be32 swcnr; /* System watchdog count register */ |
42 | u8 res1[2]; |
43 | __be16 swsrr; /* System watchdog service register */ |
44 | u8 res2[0xF0]; |
45 | }; |
46 | |
47 | struct mpc8xxx_wdt_type { |
48 | int prescaler; |
49 | bool hw_enabled; |
50 | }; |
51 | |
52 | static struct mpc8xxx_wdt __iomem *wd_base; |
53 | static int mpc8xxx_wdt_init_late(void); |
54 | |
55 | static u16 timeout = 0xffff; |
56 | module_param(timeout, ushort, 0); |
57 | MODULE_PARM_DESC(timeout, |
58 | "Watchdog timeout in ticks. (0<timeout<65536, default=65535)"); |
59 | |
60 | static bool reset = 1; |
61 | module_param(reset, bool, 0); |
62 | MODULE_PARM_DESC(reset, |
63 | "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset"); |
64 | |
65 | static bool nowayout = WATCHDOG_NOWAYOUT; |
66 | module_param(nowayout, bool, 0); |
67 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
68 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
69 | |
70 | /* |
71 | * We always prescale, but if someone really doesn't want to they can set this |
72 | * to 0 |
73 | */ |
74 | static int prescale = 1; |
75 | static unsigned int timeout_sec; |
76 | |
77 | static unsigned long wdt_is_open; |
78 | static DEFINE_SPINLOCK(wdt_spinlock); |
79 | |
80 | static void mpc8xxx_wdt_keepalive(void) |
81 | { |
82 | /* Ping the WDT */ |
83 | spin_lock(&wdt_spinlock); |
84 | out_be16(&wd_base->swsrr, 0x556c); |
85 | out_be16(&wd_base->swsrr, 0xaa39); |
86 | spin_unlock(&wdt_spinlock); |
87 | } |
88 | |
89 | static void mpc8xxx_wdt_timer_ping(unsigned long arg); |
90 | static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0); |
91 | |
92 | static void mpc8xxx_wdt_timer_ping(unsigned long arg) |
93 | { |
94 | mpc8xxx_wdt_keepalive(); |
95 | /* We're pinging it twice faster than needed, just to be sure. */ |
96 | mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2); |
97 | } |
98 | |
99 | static void mpc8xxx_wdt_pr_warn(const char *msg) |
100 | { |
101 | pr_crit("%s, expect the %s soon!\n", msg, |
102 | reset ? "reset" : "machine check exception"); |
103 | } |
104 | |
105 | static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf, |
106 | size_t count, loff_t *ppos) |
107 | { |
108 | if (count) |
109 | mpc8xxx_wdt_keepalive(); |
110 | return count; |
111 | } |
112 | |
113 | static int mpc8xxx_wdt_open(struct inode *inode, struct file *file) |
114 | { |
115 | u32 tmp = SWCRR_SWEN; |
116 | if (test_and_set_bit(0, &wdt_is_open)) |
117 | return -EBUSY; |
118 | |
119 | /* Once we start the watchdog we can't stop it */ |
120 | if (nowayout) |
121 | __module_get(THIS_MODULE); |
122 | |
123 | /* Good, fire up the show */ |
124 | if (prescale) |
125 | tmp |= SWCRR_SWPR; |
126 | if (reset) |
127 | tmp |= SWCRR_SWRI; |
128 | |
129 | tmp |= timeout << 16; |
130 | |
131 | out_be32(&wd_base->swcrr, tmp); |
132 | |
133 | del_timer_sync(&wdt_timer); |
134 | |
135 | return nonseekable_open(inode, file); |
136 | } |
137 | |
138 | static int mpc8xxx_wdt_release(struct inode *inode, struct file *file) |
139 | { |
140 | if (!nowayout) |
141 | mpc8xxx_wdt_timer_ping(0); |
142 | else |
143 | mpc8xxx_wdt_pr_warn("watchdog closed"); |
144 | clear_bit(0, &wdt_is_open); |
145 | return 0; |
146 | } |
147 | |
148 | static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd, |
149 | unsigned long arg) |
150 | { |
151 | void __user *argp = (void __user *)arg; |
152 | int __user *p = argp; |
153 | static const struct watchdog_info ident = { |
154 | .options = WDIOF_KEEPALIVEPING, |
155 | .firmware_version = 1, |
156 | .identity = "MPC8xxx", |
157 | }; |
158 | |
159 | switch (cmd) { |
160 | case WDIOC_GETSUPPORT: |
161 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; |
162 | case WDIOC_GETSTATUS: |
163 | case WDIOC_GETBOOTSTATUS: |
164 | return put_user(0, p); |
165 | case WDIOC_KEEPALIVE: |
166 | mpc8xxx_wdt_keepalive(); |
167 | return 0; |
168 | case WDIOC_GETTIMEOUT: |
169 | return put_user(timeout_sec, p); |
170 | default: |
171 | return -ENOTTY; |
172 | } |
173 | } |
174 | |
175 | static const struct file_operations mpc8xxx_wdt_fops = { |
176 | .owner = THIS_MODULE, |
177 | .llseek = no_llseek, |
178 | .write = mpc8xxx_wdt_write, |
179 | .unlocked_ioctl = mpc8xxx_wdt_ioctl, |
180 | .open = mpc8xxx_wdt_open, |
181 | .release = mpc8xxx_wdt_release, |
182 | }; |
183 | |
184 | static struct miscdevice mpc8xxx_wdt_miscdev = { |
185 | .minor = WATCHDOG_MINOR, |
186 | .name = "watchdog", |
187 | .fops = &mpc8xxx_wdt_fops, |
188 | }; |
189 | |
190 | static const struct of_device_id mpc8xxx_wdt_match[]; |
191 | static int mpc8xxx_wdt_probe(struct platform_device *ofdev) |
192 | { |
193 | int ret; |
194 | const struct of_device_id *match; |
195 | struct device_node *np = ofdev->dev.of_node; |
196 | const struct mpc8xxx_wdt_type *wdt_type; |
197 | u32 freq = fsl_get_sys_freq(); |
198 | bool enabled; |
199 | |
200 | match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev); |
201 | if (!match) |
202 | return -EINVAL; |
203 | wdt_type = match->data; |
204 | |
205 | if (!freq || freq == -1) |
206 | return -EINVAL; |
207 | |
208 | wd_base = of_iomap(np, 0); |
209 | if (!wd_base) |
210 | return -ENOMEM; |
211 | |
212 | enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN; |
213 | if (!enabled && wdt_type->hw_enabled) { |
214 | pr_info("could not be enabled in software\n"); |
215 | ret = -ENOSYS; |
216 | goto err_unmap; |
217 | } |
218 | |
219 | /* Calculate the timeout in seconds */ |
220 | if (prescale) |
221 | timeout_sec = (timeout * wdt_type->prescaler) / freq; |
222 | else |
223 | timeout_sec = timeout / freq; |
224 | |
225 | #ifdef MODULE |
226 | ret = mpc8xxx_wdt_init_late(); |
227 | if (ret) |
228 | goto err_unmap; |
229 | #endif |
230 | |
231 | pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n", |
232 | reset ? "reset" : "interrupt", timeout, timeout_sec); |
233 | |
234 | /* |
235 | * If the watchdog was previously enabled or we're running on |
236 | * MPC8xxx, we should ping the wdt from the kernel until the |
237 | * userspace handles it. |
238 | */ |
239 | if (enabled) |
240 | mpc8xxx_wdt_timer_ping(0); |
241 | return 0; |
242 | err_unmap: |
243 | iounmap(wd_base); |
244 | wd_base = NULL; |
245 | return ret; |
246 | } |
247 | |
248 | static int mpc8xxx_wdt_remove(struct platform_device *ofdev) |
249 | { |
250 | mpc8xxx_wdt_pr_warn("watchdog removed"); |
251 | del_timer_sync(&wdt_timer); |
252 | misc_deregister(&mpc8xxx_wdt_miscdev); |
253 | iounmap(wd_base); |
254 | |
255 | return 0; |
256 | } |
257 | |
258 | static const struct of_device_id mpc8xxx_wdt_match[] = { |
259 | { |
260 | .compatible = "mpc83xx_wdt", |
261 | .data = &(struct mpc8xxx_wdt_type) { |
262 | .prescaler = 0x10000, |
263 | }, |
264 | }, |
265 | { |
266 | .compatible = "fsl,mpc8610-wdt", |
267 | .data = &(struct mpc8xxx_wdt_type) { |
268 | .prescaler = 0x10000, |
269 | .hw_enabled = true, |
270 | }, |
271 | }, |
272 | { |
273 | .compatible = "fsl,mpc823-wdt", |
274 | .data = &(struct mpc8xxx_wdt_type) { |
275 | .prescaler = 0x800, |
276 | }, |
277 | }, |
278 | {}, |
279 | }; |
280 | MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match); |
281 | |
282 | static struct platform_driver mpc8xxx_wdt_driver = { |
283 | .probe = mpc8xxx_wdt_probe, |
284 | .remove = mpc8xxx_wdt_remove, |
285 | .driver = { |
286 | .name = "mpc8xxx_wdt", |
287 | .owner = THIS_MODULE, |
288 | .of_match_table = mpc8xxx_wdt_match, |
289 | }, |
290 | }; |
291 | |
292 | /* |
293 | * We do wdt initialization in two steps: arch_initcall probes the wdt |
294 | * very early to start pinging the watchdog (misc devices are not yet |
295 | * available), and later module_init() just registers the misc device. |
296 | */ |
297 | static int mpc8xxx_wdt_init_late(void) |
298 | { |
299 | int ret; |
300 | |
301 | if (!wd_base) |
302 | return -ENODEV; |
303 | |
304 | ret = misc_register(&mpc8xxx_wdt_miscdev); |
305 | if (ret) { |
306 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
307 | WATCHDOG_MINOR, ret); |
308 | return ret; |
309 | } |
310 | return 0; |
311 | } |
312 | #ifndef MODULE |
313 | module_init(mpc8xxx_wdt_init_late); |
314 | #endif |
315 | |
316 | static int __init mpc8xxx_wdt_init(void) |
317 | { |
318 | return platform_driver_register(&mpc8xxx_wdt_driver); |
319 | } |
320 | arch_initcall(mpc8xxx_wdt_init); |
321 | |
322 | static void __exit mpc8xxx_wdt_exit(void) |
323 | { |
324 | platform_driver_unregister(&mpc8xxx_wdt_driver); |
325 | } |
326 | module_exit(mpc8xxx_wdt_exit); |
327 | |
328 | MODULE_AUTHOR("Dave Updegraff, Kumar Gala"); |
329 | MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx " |
330 | "uProcessors"); |
331 | MODULE_LICENSE("GPL"); |
332 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
333 |
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