244 lines
5.8 KiB
C
244 lines
5.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Watchdog timer for PowerPC Book-E systems
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*
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* Author: Matthew McClintock
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* Maintainer: Kumar Gala <galak@kernel.crashing.org>
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*
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* Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/smp.h>
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#include <linux/watchdog.h>
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#include <asm/reg_booke.h>
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#include <asm/time.h>
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#include <asm/div64.h>
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/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
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* Also, the wdt_period sets the watchdog timer period timeout.
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* For E500 cpus the wdt_period sets which bit changing from 0->1 will
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* trigger a watchdog timeout. This watchdog timeout will occur 3 times, the
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* first time nothing will happen, the second time a watchdog exception will
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* occur, and the final time the board will reset.
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*/
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#ifdef CONFIG_PPC_E500
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#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
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#define WDTP_MASK (WDTP(0x3f))
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#else
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#define WDTP(x) (TCR_WP(x))
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#define WDTP_MASK (TCR_WP_MASK)
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#endif
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static bool booke_wdt_enabled;
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module_param(booke_wdt_enabled, bool, 0);
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static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
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module_param(booke_wdt_period, int, 0);
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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#ifdef CONFIG_PPC_E500
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/* For the specified period, determine the number of seconds
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* corresponding to the reset time. There will be a watchdog
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* exception at approximately 3/5 of this time.
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*
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* The formula to calculate this is given by:
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* 2.5 * (2^(63-period+1)) / timebase_freq
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*
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* In order to simplify things, we assume that period is
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* at least 1. This will still result in a very long timeout.
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*/
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static unsigned long long period_to_sec(unsigned int period)
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{
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unsigned long long tmp = 1ULL << (64 - period);
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unsigned long tmp2 = ppc_tb_freq;
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/* tmp may be a very large number and we don't want to overflow,
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* so divide the timebase freq instead of multiplying tmp
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*/
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tmp2 = tmp2 / 5 * 2;
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do_div(tmp, tmp2);
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return tmp;
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}
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/*
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* This procedure will find the highest period which will give a timeout
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* greater than the one required. e.g. for a bus speed of 66666666 and
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* a parameter of 2 secs, then this procedure will return a value of 38.
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*/
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static unsigned int sec_to_period(unsigned int secs)
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{
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unsigned int period;
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for (period = 63; period > 0; period--) {
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if (period_to_sec(period) >= secs)
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return period;
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}
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return 0;
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}
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#define MAX_WDT_TIMEOUT period_to_sec(1)
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#else /* CONFIG_PPC_E500 */
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static unsigned long long period_to_sec(unsigned int period)
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{
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return period;
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}
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static unsigned int sec_to_period(unsigned int secs)
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{
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return secs;
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}
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#define MAX_WDT_TIMEOUT 3 /* from Kconfig */
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#endif /* !CONFIG_PPC_E500 */
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static void __booke_wdt_set(void *data)
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{
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u32 val;
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struct watchdog_device *wdog = data;
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val = mfspr(SPRN_TCR);
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val &= ~WDTP_MASK;
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val |= WDTP(sec_to_period(wdog->timeout));
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mtspr(SPRN_TCR, val);
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}
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static void booke_wdt_set(void *data)
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{
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on_each_cpu(__booke_wdt_set, data, 0);
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}
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static void __booke_wdt_ping(void *data)
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{
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mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
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}
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static int booke_wdt_ping(struct watchdog_device *wdog)
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{
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on_each_cpu(__booke_wdt_ping, NULL, 0);
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return 0;
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}
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static void __booke_wdt_enable(void *data)
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{
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u32 val;
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struct watchdog_device *wdog = data;
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/* clear status before enabling watchdog */
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__booke_wdt_ping(NULL);
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val = mfspr(SPRN_TCR);
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val &= ~WDTP_MASK;
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val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout)));
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mtspr(SPRN_TCR, val);
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}
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/**
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* __booke_wdt_disable - disable the watchdog on the given CPU
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*
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* This function is called on each CPU. It disables the watchdog on that CPU.
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*
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* TCR[WRC] cannot be changed once it has been set to non-zero, but we can
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* effectively disable the watchdog by setting its period to the maximum value.
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*/
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static void __booke_wdt_disable(void *data)
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{
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u32 val;
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val = mfspr(SPRN_TCR);
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val &= ~(TCR_WIE | WDTP_MASK);
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mtspr(SPRN_TCR, val);
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/* clear status to make sure nothing is pending */
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__booke_wdt_ping(NULL);
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}
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static int booke_wdt_start(struct watchdog_device *wdog)
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{
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on_each_cpu(__booke_wdt_enable, wdog, 0);
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pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout);
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return 0;
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}
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static int booke_wdt_stop(struct watchdog_device *wdog)
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{
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on_each_cpu(__booke_wdt_disable, NULL, 0);
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pr_debug("watchdog disabled\n");
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return 0;
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}
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static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev,
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unsigned int timeout)
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{
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wdt_dev->timeout = timeout;
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booke_wdt_set(wdt_dev);
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return 0;
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}
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static struct watchdog_info booke_wdt_info __ro_after_init = {
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
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.identity = "PowerPC Book-E Watchdog",
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};
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static const struct watchdog_ops booke_wdt_ops = {
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.owner = THIS_MODULE,
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.start = booke_wdt_start,
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.stop = booke_wdt_stop,
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.ping = booke_wdt_ping,
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.set_timeout = booke_wdt_set_timeout,
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};
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static struct watchdog_device booke_wdt_dev = {
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.info = &booke_wdt_info,
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.ops = &booke_wdt_ops,
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.min_timeout = 1,
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};
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static void __exit booke_wdt_exit(void)
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{
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watchdog_unregister_device(&booke_wdt_dev);
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}
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static int __init booke_wdt_init(void)
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{
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int ret = 0;
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pr_info("powerpc book-e watchdog driver loaded\n");
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booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value;
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booke_wdt_set_timeout(&booke_wdt_dev,
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period_to_sec(booke_wdt_period));
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watchdog_set_nowayout(&booke_wdt_dev, nowayout);
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booke_wdt_dev.max_timeout = MAX_WDT_TIMEOUT;
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if (booke_wdt_enabled)
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booke_wdt_start(&booke_wdt_dev);
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ret = watchdog_register_device(&booke_wdt_dev);
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return ret;
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}
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module_init(booke_wdt_init);
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module_exit(booke_wdt_exit);
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MODULE_ALIAS("booke_wdt");
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MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
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MODULE_LICENSE("GPL");
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