/*
* arch/arm/mach-at91/pm_slow_clock.S
*
* Copyright (C) 2006 Savin Zlobec
*
* AT91SAM9 support:
* Copyright (C) 2007 Anti Sullin <anti.sullin@artecdesign.ee
*
* 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.
*
*/
#include <linux/linkage.h>
#include <mach/hardware.h>
#include <mach/at91_pmc.h>
#ifdef CONFIG_ARCH_AT91RM9200
#include <mach/at91rm9200_mc.h>
#elif defined(CONFIG_ARCH_AT91CAP9)
#include <mach/at91cap9_ddrsdr.h>
#else
#include <mach/at91sam9_sdramc.h>
#endif
#ifdef CONFIG_ARCH_AT91SAM9263
/*
* FIXME either or both the SDRAM controllers (EB0, EB1) might be in use;
* handle those cases both here and in the Suspend-To-RAM support.
*/
#define AT91_SDRAMC AT91_SDRAMC0
#warning Assuming EB1 SDRAM controller is *NOT* used
#endif
/*
* When SLOWDOWN_MASTER_CLOCK is defined we will also slow down the Master
* clock during suspend by adjusting its prescalar and divisor.
* NOTE: This hasn't been shown to be stable on SAM9s; and on the RM9200 there
* are errata regarding adjusting the prescalar and divisor.
*/
#undef SLOWDOWN_MASTER_CLOCK
#define MCKRDY_TIMEOUT 1000
#define MOSCRDY_TIMEOUT 1000
#define PLLALOCK_TIMEOUT 1000
#define PLLBLOCK_TIMEOUT 1000
/*
* Wait until master clock is ready (after switching master clock source)
*/
.macro wait_mckrdy
mov r4, #MCKRDY_TIMEOUT
1: sub r4, r4, #1
cmp r4, #0
beq 2f
ldr r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
tst r3, #AT91_PMC_MCKRDY
beq 1b
2:
.endm
/*
* Wait until master oscillator has stabilized.
*/
.macro wait_moscrdy
mov r4, #MOSCRDY_TIMEOUT
1: sub r4, r4, #1
cmp r4, #0
beq 2f
ldr r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
tst r3, #AT91_PMC_MOSCS
beq 1b
2:
.endm
/*
* Wait until PLLA has locked.
*/
.macro wait_pllalock
mov r4, #PLLALOCK_TIMEOUT
1: sub r4, r4, #1
cmp r4, #0
beq 2f
ldr r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
tst r3, #AT91_PMC_LOCKA
beq 1b
2:
.endm
/*
* Wait until PLLB has locked.
*/
.macro wait_pllblock
mov r4, #PLLBLOCK_TIMEOUT
1: sub r4, r4, #1
cmp r4, #0
beq 2f
ldr r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
tst r3, #AT91_PMC_LOCKB
beq 1b
2:
.endm
.text
ENTRY(at91_slow_clock)
/* Save registers on stack */
stmfd sp!, {r0 - r12, lr}
/*
* Register usage:
* R1 = Base address of AT91_PMC
* R2 = Base address of AT91_SDRAMC (or AT91_SYS on AT91RM9200)
* R3 = temporary register
* R4 = temporary register
*/
ldr r1, .at91_va_base_pmc
ldr r2, .at91_va_base_sdramc
/* Drain write buffer */
mcr p15, 0, r0, c7, c10, 4
#ifdef CONFIG_ARCH_AT91RM9200
/* Put SDRAM in self-refresh mode */
mov r3, #1
str r3, [r2, #AT91_SDRAMC_SRR]
#elif defined(CONFIG_ARCH_AT91CAP9)
/* Enable SDRAM self-refresh mode */
ldr r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
str r3, .saved_sam9_lpr
mov r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
str r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
#else
/* Enable SDRAM self-refresh mode */
ldr r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
str r3, .saved_sam9_lpr
mov r3, #AT91_SDRAMC_LPCB_SELF_REFRESH
str r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
#endif
/* Save Master clock setting */
ldr r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
str r3, .saved_mckr
/*
* Set the Master clock source to slow clock
*/
bic r3, r3, #AT91_PMC_CSS
str r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
wait_mckrdy
#ifdef SLOWDOWN_MASTER_CLOCK
/*
* Set the Master Clock PRES and MDIV fields.
*
* See AT91RM9200 errata #27 and #28 for details.
*/
mov r3, #0
str r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
wait_mckrdy
#endif
/* Save PLLA setting and disable it */
ldr r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
str r3, .saved_pllar
mov r3, #AT91_PMC_PLLCOUNT
orr r3, r3, #(1 << 29) /* bit 29 always set */
str r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
wait_pllalock
/* Save PLLB setting and disable it */
ldr r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
str r3, .saved_pllbr
mov r3, #AT91_PMC_PLLCOUNT
str r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
wait_pllblock
/* Turn off the main oscillator */
ldr r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
bic r3, r3, #AT91_PMC_MOSCEN
str r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
/* Wait for interrupt */
mcr p15, 0, r0, c7, c0, 4
/* Turn on the main oscillator */
ldr r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
orr r3, r3, #AT91_PMC_MOSCEN
str r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
wait_moscrdy
/* Restore PLLB setting */
ldr r3, .saved_pllbr
str r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
wait_pllblock
/* Restore PLLA setting */
ldr r3, .saved_pllar
str r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
wait_pllalock
#ifdef SLOWDOWN_MASTER_CLOCK
/*
* First set PRES if it was not 0,
* than set CSS and MDIV fields.
*
* See AT91RM9200 errata #27 and #28 for details.
*/
ldr r3, .saved_mckr
tst r3, #AT91_PMC_PRES
beq 2f
and r3, r3, #AT91_PMC_PRES
str r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
wait_mckrdy
#endif
/*
* Restore master clock setting
*/
2: ldr r3, .saved_mckr
str r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
wait_mckrdy
#ifdef CONFIG_ARCH_AT91RM9200
/* Do nothing - self-refresh is automatically disabled. */
#elif defined(CONFIG_ARCH_AT91CAP9)
/* Restore LPR on AT91CAP9 */
ldr r3, .saved_sam9_lpr
str r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
#else
/* Restore LPR on AT91SAM9 */
ldr r3, .saved_sam9_lpr
str r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
#endif
/* Restore registers, and return */
ldmfd sp!, {r0 - r12, pc}
.saved_mckr:
.word 0
.saved_pllar:
.word 0
.saved_pllbr:
.word 0
.saved_sam9_lpr:
.word 0
.at91_va_base_pmc:
.word AT91_VA_BASE_SYS + AT91_PMC
#ifdef CONFIG_ARCH_AT91RM9200
.at91_va_base_sdramc:
.word AT91_VA_BASE_SYS
#elif defined(CONFIG_ARCH_AT91CAP9)
.at91_va_base_sdramc:
.word AT91_VA_BASE_SYS + AT91_DDRSDRC
#else
.at91_va_base_sdramc:
.word AT91_VA_BASE_SYS + AT91_SDRAMC
#endif
ENTRY(at91_slow_clock_sz)
.word .-at91_slow_clock
