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[ARM] 4412/1: S3C2412: reset errata fix

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The S3C2412 has an reset-errata where the clock
may cause a glitch switching back to EXTCLK. We
force a switch to EXTCLK before writing the
reset register to force use of the CLKCON sync
logic to properly switch.

Fix problem reported by Matthieu Castet.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Ben Dooks 2007-05-28 18:19:16 +01:00 committed by Russell King
parent 486cab2ba2
commit eca8c24241
2 changed files with 45 additions and 0 deletions
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24
arch/arm/mach-s3c2412/s3c2412.c
View File

@ -16,6 +16,7 @@
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sysdev.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
@ -29,6 +30,7 @@
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/arch/reset.h>
#include <asm/arch/idle.h>
#include <asm/arch/regs-clock.h>
@ -38,6 +40,7 @@
#include <asm/arch/regs-gpioj.h>
#include <asm/arch/regs-dsc.h>
#include <asm/arch/regs-spi.h>
#include <asm/arch/regs-s3c2412.h>
#include <asm/plat-s3c24xx/s3c2412.h>
#include <asm/plat-s3c24xx/cpu.h>
@ -106,6 +109,23 @@ static void s3c2412_idle(void)
cpu_do_idle();
}
static void s3c2412_hard_reset(void)
{
/* errata "Watch-dog/Software Reset Problem" specifies that
* this reset must be done with the SYSCLK sourced from
* EXTCLK instead of FOUT to avoid a glitch in the reset
* mechanism.
*
* See the watchdog section of the S3C2412 manual for more
* information on this fix.
*/
__raw_writel(0x00, S3C2412_CLKSRC);
__raw_writel(S3C2412_SWRST_RESET, S3C2412_SWRST);
mdelay(1);
}
/* s3c2412_map_io
*
* register the standard cpu IO areas, and any passed in from the
@ -122,6 +142,10 @@ void __init s3c2412_map_io(struct map_desc *mach_desc, int mach_size)
s3c24xx_idle = s3c2412_idle;
/* set custom reset hook */
s3c24xx_reset_hook = s3c2412_hard_reset;
/* register our io-tables */
iotable_init(s3c2412_iodesc, ARRAY_SIZE(s3c2412_iodesc));

21
include/asm-arm/arch-s3c2410/regs-s3c2412.h Normal file
View File

@ -0,0 +1,21 @@
/* linux/include/asm-arm/arch-s3c2410/regs-s3c2412.h
*
* Copyright 2007 Simtec Electronics
* http://armlinux.simtec.co.uk/
* Ben Dooks <ben@simtec.co.uk>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* S3C2412 specific register definitions
*/
#ifndef __ASM_ARCH_REGS_S3C2412_H
#define __ASM_ARCH_REGS_S3C2412_H "s3c2412"
#define S3C2412_SWRST (S3C24XX_VA_CLKPWR + 0x30)
#define S3C2412_SWRST_RESET (0x533C2412)
#endif /* __ASM_ARCH_REGS_S3C2412_H */