2 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
4 * Authors: Dave Updegraff <dave@cray.org>
5 * Kumar Gala <galak@kernel.crashing.org>
6 * Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
8 * Copyright (c) 2008 MontaVista Software, Inc.
9 * Anton Vorontsov <avorontsov@ru.mvista.com>
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.
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.
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/timer.h>
26 #include <linux/miscdevice.h>
27 #include <linux/of_address.h>
28 #include <linux/of_platform.h>
29 #include <linux/module.h>
30 #include <linux/watchdog.h>
32 #include <linux/uaccess.h>
33 #include <sysdev/fsl_soc.h>
37 __be32 swcrr; /* System watchdog control register */
38 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
39 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
40 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
41 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
42 __be32 swcnr; /* System watchdog count register */
44 __be16 swsrr; /* System watchdog service register */
48 struct mpc8xxx_wdt_type {
53 static struct mpc8xxx_wdt __iomem *wd_base;
54 static int mpc8xxx_wdt_init_late(void);
56 static u16 timeout = 0xffff;
57 module_param(timeout, ushort, 0);
58 MODULE_PARM_DESC(timeout,
59 "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
61 static bool reset = 1;
62 module_param(reset, bool, 0);
63 MODULE_PARM_DESC(reset,
64 "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
66 static bool nowayout = WATCHDOG_NOWAYOUT;
67 module_param(nowayout, bool, 0);
68 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
69 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
72 * We always prescale, but if someone really doesn't want to they can set this
75 static int prescale = 1;
76 static unsigned int timeout_sec;
78 static unsigned long wdt_is_open;
79 static DEFINE_SPINLOCK(wdt_spinlock);
81 static void mpc8xxx_wdt_keepalive(void)
84 spin_lock(&wdt_spinlock);
85 out_be16(&wd_base->swsrr, 0x556c);
86 out_be16(&wd_base->swsrr, 0xaa39);
87 spin_unlock(&wdt_spinlock);
90 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
91 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
93 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
95 mpc8xxx_wdt_keepalive();
96 /* We're pinging it twice faster than needed, just to be sure. */
97 mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
100 static void mpc8xxx_wdt_pr_warn(const char *msg)
102 pr_crit("%s, expect the %s soon!\n", msg,
103 reset ? "reset" : "machine check exception");
106 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
107 size_t count, loff_t *ppos)
110 mpc8xxx_wdt_keepalive();
114 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
116 u32 tmp = SWCRR_SWEN;
117 if (test_and_set_bit(0, &wdt_is_open))
120 /* Once we start the watchdog we can't stop it */
122 __module_get(THIS_MODULE);
124 /* Good, fire up the show */
130 tmp |= timeout << 16;
132 out_be32(&wd_base->swcrr, tmp);
134 del_timer_sync(&wdt_timer);
136 return nonseekable_open(inode, file);
139 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
142 mpc8xxx_wdt_timer_ping(0);
144 mpc8xxx_wdt_pr_warn("watchdog closed");
145 clear_bit(0, &wdt_is_open);
149 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
152 void __user *argp = (void __user *)arg;
153 int __user *p = argp;
154 static const struct watchdog_info ident = {
155 .options = WDIOF_KEEPALIVEPING,
156 .firmware_version = 1,
157 .identity = "MPC8xxx",
161 case WDIOC_GETSUPPORT:
162 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
163 case WDIOC_GETSTATUS:
164 case WDIOC_GETBOOTSTATUS:
165 return put_user(0, p);
166 case WDIOC_KEEPALIVE:
167 mpc8xxx_wdt_keepalive();
169 case WDIOC_GETTIMEOUT:
170 return put_user(timeout_sec, p);
176 static const struct file_operations mpc8xxx_wdt_fops = {
177 .owner = THIS_MODULE,
179 .write = mpc8xxx_wdt_write,
180 .unlocked_ioctl = mpc8xxx_wdt_ioctl,
181 .open = mpc8xxx_wdt_open,
182 .release = mpc8xxx_wdt_release,
185 static struct miscdevice mpc8xxx_wdt_miscdev = {
186 .minor = WATCHDOG_MINOR,
188 .fops = &mpc8xxx_wdt_fops,
191 static const struct of_device_id mpc8xxx_wdt_match[];
192 static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
195 const struct of_device_id *match;
196 struct device_node *np = ofdev->dev.of_node;
197 const struct mpc8xxx_wdt_type *wdt_type;
198 u32 freq = fsl_get_sys_freq();
201 match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
204 wdt_type = match->data;
206 if (!freq || freq == -1)
209 wd_base = of_iomap(np, 0);
213 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
214 if (!enabled && wdt_type->hw_enabled) {
215 pr_info("could not be enabled in software\n");
220 /* Calculate the timeout in seconds */
222 timeout_sec = (timeout * wdt_type->prescaler) / freq;
224 timeout_sec = timeout / freq;
227 ret = mpc8xxx_wdt_init_late();
232 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
233 reset ? "reset" : "interrupt", timeout, timeout_sec);
236 * If the watchdog was previously enabled or we're running on
237 * MPC8xxx, we should ping the wdt from the kernel until the
238 * userspace handles it.
241 mpc8xxx_wdt_timer_ping(0);
249 static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
251 mpc8xxx_wdt_pr_warn("watchdog removed");
252 del_timer_sync(&wdt_timer);
253 misc_deregister(&mpc8xxx_wdt_miscdev);
259 static const struct of_device_id mpc8xxx_wdt_match[] = {
261 .compatible = "mpc83xx_wdt",
262 .data = &(struct mpc8xxx_wdt_type) {
263 .prescaler = 0x10000,
267 .compatible = "fsl,mpc8610-wdt",
268 .data = &(struct mpc8xxx_wdt_type) {
269 .prescaler = 0x10000,
274 .compatible = "fsl,mpc823-wdt",
275 .data = &(struct mpc8xxx_wdt_type) {
281 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
283 static struct platform_driver mpc8xxx_wdt_driver = {
284 .probe = mpc8xxx_wdt_probe,
285 .remove = mpc8xxx_wdt_remove,
287 .name = "mpc8xxx_wdt",
288 .owner = THIS_MODULE,
289 .of_match_table = mpc8xxx_wdt_match,
294 * We do wdt initialization in two steps: arch_initcall probes the wdt
295 * very early to start pinging the watchdog (misc devices are not yet
296 * available), and later module_init() just registers the misc device.
298 static int mpc8xxx_wdt_init_late(void)
305 ret = misc_register(&mpc8xxx_wdt_miscdev);
307 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
308 WATCHDOG_MINOR, ret);
314 module_init(mpc8xxx_wdt_init_late);
317 static int __init mpc8xxx_wdt_init(void)
319 return platform_driver_register(&mpc8xxx_wdt_driver);
321 arch_initcall(mpc8xxx_wdt_init);
323 static void __exit mpc8xxx_wdt_exit(void)
325 platform_driver_unregister(&mpc8xxx_wdt_driver);
327 module_exit(mpc8xxx_wdt_exit);
329 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
330 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
332 MODULE_LICENSE("GPL");