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The OMAP WDT IP block requires to be stopped before any write to its registers is performed. This problem has been thoroughly described in Linux kernel: "watchdog: omap: assert the counter being stopped before reprogramming: SHA1: 530c11d432727c697629ad5f9d00ee8e2864d453 Signed-off-by: Lukasz Majewski <lukma@denx.de> Reviewed-by: Tom Rini <trini@konsulko.com>
128 lines
3 KiB
C
128 lines
3 KiB
C
/*
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* omap_wdt.c
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*
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* (C) Copyright 2013
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* Heiko Schocher, DENX Software Engineering, hs@denx.de.
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*
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* SPDX-License-Identifier: GPL-2.0
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*
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* Based on:
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*
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* Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
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*
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* commit 2d991a164a61858012651e13c59521975504e260
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* Author: Bill Pemberton <wfp5p@virginia.edu>
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* Date: Mon Nov 19 13:21:41 2012 -0500
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*
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* watchdog: remove use of __devinit
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*
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* CONFIG_HOTPLUG is going away as an option so __devinit is no longer
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* needed.
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*
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* Author: MontaVista Software, Inc.
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* <gdavis@mvista.com> or <source@mvista.com>
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*
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* History:
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*
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* 20030527: George G. Davis <gdavis@mvista.com>
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* Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
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* (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
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* Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Copyright (c) 2004 Texas Instruments.
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* 1. Modified to support OMAP1610 32-KHz watchdog timer
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* 2. Ported to 2.6 kernel
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*
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* Copyright (c) 2005 David Brownell
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* Use the driver model and standard identifiers; handle bigger timeouts.
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*/
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#include <common.h>
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#include <watchdog.h>
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#include <asm/arch/hardware.h>
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#include <asm/io.h>
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#include <asm/processor.h>
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#include <asm/arch/cpu.h>
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/* Hardware timeout in seconds */
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#define WDT_HW_TIMEOUT 60
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static unsigned int wdt_trgr_pattern = 0x1234;
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void hw_watchdog_reset(void)
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{
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struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
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/* wait for posted write to complete */
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while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WTGR)
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;
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wdt_trgr_pattern = ~wdt_trgr_pattern;
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writel(wdt_trgr_pattern, &wdt->wdtwtgr);
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/* wait for posted write to complete */
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while ((readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WTGR))
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;
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}
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static int omap_wdt_set_timeout(unsigned int timeout)
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{
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struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
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u32 pre_margin = GET_WLDR_VAL(timeout);
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/* just count up at 32 KHz */
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while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WLDR)
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;
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writel(pre_margin, &wdt->wdtwldr);
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while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WLDR)
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;
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return 0;
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}
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void hw_watchdog_disable(void)
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{
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struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
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/*
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* Disable watchdog
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*/
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writel(0xAAAA, &wdt->wdtwspr);
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while (readl(&wdt->wdtwwps) != 0x0)
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;
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writel(0x5555, &wdt->wdtwspr);
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while (readl(&wdt->wdtwwps) != 0x0)
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;
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}
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void hw_watchdog_init(void)
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{
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struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
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/*
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* Make sure the watchdog is disabled. This is unfortunately required
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* because writing to various registers with the watchdog running has no
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* effect.
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*/
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hw_watchdog_disable();
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/* initialize prescaler */
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while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
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;
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writel(WDT_WCLR_PRE | (PTV << WDT_WCLR_PTV_OFF), &wdt->wdtwclr);
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while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
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;
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omap_wdt_set_timeout(WDT_HW_TIMEOUT);
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/* Sequence to enable the watchdog */
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writel(0xBBBB, &wdt->wdtwspr);
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while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
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;
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writel(0x4444, &wdt->wdtwspr);
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while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
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;
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}
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