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b1608d69cb
Commit b826291c, "drivercore/dt: add a match table pointer to struct
device" added an of_match pointer to struct device to cache the
of_match_table entry discovered at driver match time. This was unsafe
because matching is not an atomic operation with probing a driver. If
two or more drivers are attempted to be matched to a driver at the
same time, then the cached matching entry pointer could get
overwritten.
This patch reverts the of_match cache pointer and reworks all users to
call of_match_device() directly instead.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
331 lines
8.1 KiB
C
331 lines
8.1 KiB
C
/*
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* mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
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*
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* Authors: Dave Updegraff <dave@cray.org>
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* Kumar Gala <galak@kernel.crashing.org>
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* Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
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* ..and from sc520_wdt
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* Copyright (c) 2008 MontaVista Software, Inc.
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* Anton Vorontsov <avorontsov@ru.mvista.com>
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*
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* Note: it appears that you can only actually ENABLE or DISABLE the thing
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* once after POR. Once enabled, you cannot disable, and vice versa.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/miscdevice.h>
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#include <linux/of_platform.h>
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#include <linux/module.h>
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#include <linux/watchdog.h>
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#include <linux/io.h>
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#include <linux/uaccess.h>
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#include <sysdev/fsl_soc.h>
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struct mpc8xxx_wdt {
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__be32 res0;
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__be32 swcrr; /* System watchdog control register */
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#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
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#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
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#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
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#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
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__be32 swcnr; /* System watchdog count register */
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u8 res1[2];
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__be16 swsrr; /* System watchdog service register */
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u8 res2[0xF0];
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};
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struct mpc8xxx_wdt_type {
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int prescaler;
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bool hw_enabled;
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};
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static struct mpc8xxx_wdt __iomem *wd_base;
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static int mpc8xxx_wdt_init_late(void);
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static u16 timeout = 0xffff;
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module_param(timeout, ushort, 0);
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MODULE_PARM_DESC(timeout,
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"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
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static int reset = 1;
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module_param(reset, bool, 0);
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MODULE_PARM_DESC(reset,
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"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
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static int nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
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"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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/*
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* We always prescale, but if someone really doesn't want to they can set this
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* to 0
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*/
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static int prescale = 1;
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static unsigned int timeout_sec;
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static unsigned long wdt_is_open;
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static DEFINE_SPINLOCK(wdt_spinlock);
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static void mpc8xxx_wdt_keepalive(void)
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{
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/* Ping the WDT */
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spin_lock(&wdt_spinlock);
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out_be16(&wd_base->swsrr, 0x556c);
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out_be16(&wd_base->swsrr, 0xaa39);
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spin_unlock(&wdt_spinlock);
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}
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static void mpc8xxx_wdt_timer_ping(unsigned long arg);
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static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
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static void mpc8xxx_wdt_timer_ping(unsigned long arg)
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{
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mpc8xxx_wdt_keepalive();
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/* We're pinging it twice faster than needed, just to be sure. */
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mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
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}
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static void mpc8xxx_wdt_pr_warn(const char *msg)
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{
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pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
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reset ? "reset" : "machine check exception");
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}
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static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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if (count)
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mpc8xxx_wdt_keepalive();
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return count;
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}
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static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
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{
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u32 tmp = SWCRR_SWEN;
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if (test_and_set_bit(0, &wdt_is_open))
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return -EBUSY;
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/* Once we start the watchdog we can't stop it */
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if (nowayout)
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__module_get(THIS_MODULE);
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/* Good, fire up the show */
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if (prescale)
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tmp |= SWCRR_SWPR;
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if (reset)
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tmp |= SWCRR_SWRI;
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tmp |= timeout << 16;
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out_be32(&wd_base->swcrr, tmp);
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del_timer_sync(&wdt_timer);
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return nonseekable_open(inode, file);
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}
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static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
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{
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if (!nowayout)
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mpc8xxx_wdt_timer_ping(0);
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else
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mpc8xxx_wdt_pr_warn("watchdog closed");
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clear_bit(0, &wdt_is_open);
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return 0;
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}
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static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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static const struct watchdog_info ident = {
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.options = WDIOF_KEEPALIVEPING,
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.firmware_version = 1,
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.identity = "MPC8xxx",
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_KEEPALIVE:
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mpc8xxx_wdt_keepalive();
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return 0;
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case WDIOC_GETTIMEOUT:
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return put_user(timeout_sec, p);
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default:
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return -ENOTTY;
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}
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}
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static const struct file_operations mpc8xxx_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = mpc8xxx_wdt_write,
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.unlocked_ioctl = mpc8xxx_wdt_ioctl,
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.open = mpc8xxx_wdt_open,
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.release = mpc8xxx_wdt_release,
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};
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static struct miscdevice mpc8xxx_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &mpc8xxx_wdt_fops,
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};
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static const struct of_device_id mpc8xxx_wdt_match[];
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static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
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{
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int ret;
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const struct of_device_id *match;
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struct device_node *np = ofdev->dev.of_node;
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struct mpc8xxx_wdt_type *wdt_type;
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u32 freq = fsl_get_sys_freq();
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bool enabled;
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match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
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if (!match)
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return -EINVAL;
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wdt_type = match->data;
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if (!freq || freq == -1)
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return -EINVAL;
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wd_base = of_iomap(np, 0);
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if (!wd_base)
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return -ENOMEM;
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enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
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if (!enabled && wdt_type->hw_enabled) {
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pr_info("mpc8xxx_wdt: could not be enabled in software\n");
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ret = -ENOSYS;
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goto err_unmap;
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}
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/* Calculate the timeout in seconds */
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if (prescale)
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timeout_sec = (timeout * wdt_type->prescaler) / freq;
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else
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timeout_sec = timeout / freq;
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#ifdef MODULE
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ret = mpc8xxx_wdt_init_late();
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if (ret)
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goto err_unmap;
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#endif
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pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
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"(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
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timeout_sec);
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/*
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* If the watchdog was previously enabled or we're running on
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* MPC8xxx, we should ping the wdt from the kernel until the
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* userspace handles it.
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*/
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if (enabled)
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mpc8xxx_wdt_timer_ping(0);
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return 0;
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err_unmap:
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iounmap(wd_base);
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wd_base = NULL;
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return ret;
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}
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static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
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{
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mpc8xxx_wdt_pr_warn("watchdog removed");
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del_timer_sync(&wdt_timer);
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misc_deregister(&mpc8xxx_wdt_miscdev);
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iounmap(wd_base);
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return 0;
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}
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static const struct of_device_id mpc8xxx_wdt_match[] = {
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{
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.compatible = "mpc83xx_wdt",
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.data = &(struct mpc8xxx_wdt_type) {
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.prescaler = 0x10000,
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},
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},
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{
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.compatible = "fsl,mpc8610-wdt",
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.data = &(struct mpc8xxx_wdt_type) {
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.prescaler = 0x10000,
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.hw_enabled = true,
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},
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},
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{
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.compatible = "fsl,mpc823-wdt",
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.data = &(struct mpc8xxx_wdt_type) {
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.prescaler = 0x800,
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},
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},
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{},
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};
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MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
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static struct platform_driver mpc8xxx_wdt_driver = {
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.probe = mpc8xxx_wdt_probe,
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.remove = __devexit_p(mpc8xxx_wdt_remove),
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.driver = {
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.name = "mpc8xxx_wdt",
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.owner = THIS_MODULE,
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.of_match_table = mpc8xxx_wdt_match,
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},
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};
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/*
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* We do wdt initialization in two steps: arch_initcall probes the wdt
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* very early to start pinging the watchdog (misc devices are not yet
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* available), and later module_init() just registers the misc device.
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*/
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static int mpc8xxx_wdt_init_late(void)
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{
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int ret;
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if (!wd_base)
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return -ENODEV;
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ret = misc_register(&mpc8xxx_wdt_miscdev);
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if (ret) {
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pr_err("cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, ret);
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return ret;
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}
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return 0;
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}
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#ifndef MODULE
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module_init(mpc8xxx_wdt_init_late);
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#endif
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static int __init mpc8xxx_wdt_init(void)
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{
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return platform_driver_register(&mpc8xxx_wdt_driver);
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}
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arch_initcall(mpc8xxx_wdt_init);
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static void __exit mpc8xxx_wdt_exit(void)
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{
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platform_driver_unregister(&mpc8xxx_wdt_driver);
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}
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module_exit(mpc8xxx_wdt_exit);
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MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
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MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
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"uProcessors");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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