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[PATCH] ARM: 2650/1: PXA27x sleep - workaround Errata 39 & 50 (Patch 2667)

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Patch from Jeff Lackey

This patch updates arch/arm/mach-pxa/sleep.S to support
the PXA270 CPU.  It works around Errata 39 & 50 from the
Intel(R) PXA27x Processor Family Specification Update.

Signed-off-by: Jeff Lackey
Signed-off-by: Russell King
This commit is contained in:
Jeff Lackey 2005-04-25 23:38:55 +01:00 committed by Russell King
parent eec99e345e
commit 41130d37a4
1 changed files with 52 additions and 8 deletions
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60
arch/arm/mach-pxa/sleep.S
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@ -18,6 +18,11 @@
#include <asm/arch/pxa-regs.h>
#ifdef CONFIG_PXA27x // workaround for Errata 50
#define MDREFR_KDIV 0x200a4000 // all banks
#define CCCR_SLEEP 0x00000107 // L=7 2N=2 A=0 PPDIS=0 CPDIS=0
#endif
.text
/*
@ -28,7 +33,9 @@
ENTRY(pxa_cpu_suspend)
#ifndef CONFIG_IWMMXT
mra r2, r3, acc0
#endif
stmfd sp!, {r2 - r12, lr} @ save registers on stack
@ get coprocessor registers
@ -61,14 +68,23 @@ ENTRY(pxa_cpu_suspend)
@ prepare value for sleep mode
mov r1, #3 @ sleep mode
@ prepare to put SDRAM into self-refresh manually
ldr r4, =MDREFR
ldr r5, [r4]
orr r5, r5, #MDREFR_SLFRSH
@ prepare pointer to physical address 0 (virtual mapping in generic.c)
mov r2, #UNCACHED_PHYS_0
@ prepare SDRAM refresh settings
ldr r4, =MDREFR
ldr r5, [r4]
@ enable SDRAM self-refresh mode
orr r5, r5, #MDREFR_SLFRSH
#ifdef CONFIG_PXA27x
@ set SDCLKx divide-by-2 bits (this is part of a workaround for Errata 50)
ldr r6, =MDREFR_KDIV
orr r5, r5, r6
#endif
#ifdef CONFIG_PXA25x
@ Intel PXA255 Specification Update notes problems
@ about suspending with PXBus operating above 133MHz
@ (see Errata 31, GPIO output signals, ... unpredictable in sleep
@ -100,6 +116,18 @@ ENTRY(pxa_cpu_suspend)
mov r0, #0
mcr p14, 0, r0, c6, c0, 0
orr r0, r0, #2 @ initiate change bit
#endif
#ifdef CONFIG_PXA27x
@ Intel PXA270 Specification Update notes problems sleeping
@ with core operating above 91 MHz
@ (see Errata 50, ...processor does not exit from sleep...)
ldr r6, =CCCR
ldr r8, [r6] @ keep original value for resume
ldr r7, =CCCR_SLEEP @ prepare CCCR sleep value
mov r0, #0x2 @ prepare value for CLKCFG
#endif
@ align execution to a cache line
b 1f
@ -111,6 +139,7 @@ ENTRY(pxa_cpu_suspend)
@ All needed values are now in registers.
@ These last instructions should be in cache
#if defined(CONFIG_PXA25x) || defined(CONFIG_PXA27x)
@ initiate the frequency change...
str r7, [r6]
mcr p14, 0, r0, c6, c0, 0
@ -118,14 +147,27 @@ ENTRY(pxa_cpu_suspend)
@ restore the original cpu speed value for resume
str r8, [r6]
@ put SDRAM into self-refresh
str r5, [r4]
@ need 6 13-MHz cycles before changing PWRMODE
@ just set frequency to 91-MHz... 6*91/13 = 42
mov r0, #42
10: subs r0, r0, #1
bne 10b
#endif
@ Do not reorder...
@ Intel PXA270 Specification Update notes problems performing
@ external accesses after SDRAM is put in self-refresh mode
@ (see Errata 39 ...hangs when entering self-refresh mode)
@ force address lines low by reading at physical address 0
ldr r3, [r2]
@ put SDRAM into self-refresh
str r5, [r4]
@ enter sleep mode
mcr p14, 0, r1, c7, c0, 0
mcr p14, 0, r1, c7, c0, 0 @ PWRMODE
20: b 20b @ loop waiting for sleep
@ -188,7 +230,9 @@ resume_after_mmu:
bl cpu_xscale_proc_init
#endif
ldmfd sp!, {r2, r3}
#ifndef CONFIG_IWMMXT
mar acc0, r2, r3
#endif
ldmfd sp!, {r4 - r12, pc} @ return to caller