kernel-ark/arch/powerpc/kernel/cpu_setup_44x.S
Valentine Barshak 340ffd267c [POWERPC] 4xx: 440EPx/GRx incorrect write to DDR SDRAM errata workaround
Add a workaround for PowerPC 440EPx/GRx incorrect write to
DDR SDRAM errata. Data can be written to wrong address
in SDRAM when write pipelining enabled on plb0. We disable
it in the cpu_setup for these processors at early init.

Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
2007-10-03 07:20:18 -05:00

57 lines
1.3 KiB
ArmAsm

/*
* This file contains low level CPU setup functions.
* Valentine Barshak <vbarshak@ru.mvista.com>
* MontaVista Software, Inc (c) 2007
*
* Based on cpu_setup_6xx code by
* Benjamin Herrenschmidt <benh@kernel.crashing.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/ppc_asm.h>
_GLOBAL(__setup_cpu_440ep)
b __init_fpu_44x
_GLOBAL(__setup_cpu_440epx)
mflr r4
bl __init_fpu_44x
bl __plb_disable_wrp
mtlr r4
blr
_GLOBAL(__setup_cpu_440grx)
b __plb_disable_wrp
/* enable APU between CPU and FPU */
_GLOBAL(__init_fpu_44x)
mfspr r3,SPRN_CCR0
/* Clear DAPUIB flag in CCR0 */
rlwinm r3,r3,0,12,10
mtspr SPRN_CCR0,r3
isync
blr
/*
* Workaround for the incorrect write to DDR SDRAM errata.
* The write address can be corrupted during writes to
* DDR SDRAM when write pipelining is enabled on PLB0.
* Disable write pipelining here.
*/
#define DCRN_PLB4A0_ACR 0x81
_GLOBAL(__plb_disable_wrp)
mfdcr r3,DCRN_PLB4A0_ACR
/* clear WRP bit in PLB4A0_ACR */
rlwinm r3,r3,0,8,6
mtdcr DCRN_PLB4A0_ACR,r3
isync
blr