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Commit eca8c242 authored by Ben Dooks's avatar Ben Dooks Committed by Russell King
Browse files

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



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: default avatarBen Dooks <ben-linux@fluff.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 486cab2b

arch/arm/mach-s3c2412/s3c2412.c

+24 −0
Original line number Diff line number Diff line
@@ -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));

include/asm-arm/arch-s3c2410/regs-s3c2412.h

0 → 100644
+21 −0
Original line number Diff line number Diff line 
/* 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 */