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/*
* 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 <linux/clk/at91_pmc.h>
#include <mach/hardware.h>
#include <mach/at91_ramc.h>
/*
* 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
pmc .req r0
sdramc .req r1
ramc1 .req r2
memctrl .req r3
tmp1 .req r4
tmp2 .req r5
/*
* Wait until master clock is ready (after switching master clock source)
*/
.macro wait_mckrdy
1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_MCKRDY
beq 1b
.endm
/*
* Wait until master oscillator has stabilized.
*/
.macro wait_moscrdy
1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_MOSCS
beq 1b
.endm
/*
* Wait until PLLA has locked.
*/
.macro wait_pllalock
1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_LOCKA
beq 1b
.endm
/*
* Wait until PLLB has locked.
*/
.macro wait_pllblock
1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_LOCKB
beq 1b
.endm
.text
/* void at91_slow_clock(void __iomem *pmc, void __iomem *sdramc,
* void __iomem *ramc1, int memctrl)
*/
ENTRY(at91_slow_clock)
/* Save registers on stack */
stmfd sp!, {r4 - r12, lr}
/*
* Register usage:
* R0 = Base address of AT91_PMC
* R1 = Base address of RAM Controller (SDRAM, DDRSDR, or AT91_SYS)
* R2 = Base address of second RAM Controller or 0 if not present
* R3 = Memory controller
* R4 = temporary register
* R5 = temporary register
*/
/* Drain write buffer */
mov tmp1, #0
mcr p15, 0, tmp1, c7, c10, 4
cmp memctrl, #AT91_MEMCTRL_MC
bne ddr_sr_enable
/*
* at91rm9200 Memory controller
*/
/* Put SDRAM in self-refresh mode */
mov tmp1, #1
str tmp1, [sdramc, #AT91RM9200_SDRAMC_SRR]
b sdr_sr_done
/*
* DDRSDR Memory controller
*/
ddr_sr_enable:
cmp memctrl, #AT91_MEMCTRL_DDRSDR
bne sdr_sr_enable
/* prepare for DDRAM self-refresh mode */
ldr tmp1, [sdramc, #AT91_DDRSDRC_LPR]
str tmp1, .saved_sam9_lpr
bic tmp1, #AT91_DDRSDRC_LPCB
orr tmp1, #AT91_DDRSDRC_LPCB_SELF_REFRESH
/* figure out if we use the second ram controller */
cmp ramc1, #0
ldrne tmp2, [ramc1, #AT91_DDRSDRC_LPR]
strne tmp2, .saved_sam9_lpr1
bicne tmp2, #AT91_DDRSDRC_LPCB
orrne tmp2, #AT91_DDRSDRC_LPCB_SELF_REFRESH
/* Enable DDRAM self-refresh mode */
str tmp1, [sdramc, #AT91_DDRSDRC_LPR]
strne tmp2, [ramc1, #AT91_DDRSDRC_LPR]
b sdr_sr_done
/*
* SDRAMC Memory controller
*/
sdr_sr_enable:
/* Enable SDRAM self-refresh mode */
ldr tmp1, [sdramc, #AT91_SDRAMC_LPR]
str tmp1, .saved_sam9_lpr
bic tmp1, #AT91_SDRAMC_LPCB
orr tmp1, #AT91_SDRAMC_LPCB_SELF_REFRESH
str tmp1, [sdramc, #AT91_SDRAMC_LPR]
sdr_sr_done:
/* Save Master clock setting */
ldr tmp1, [pmc, #AT91_PMC_MCKR]
str tmp1, .saved_mckr
/*
* Set the Master clock source to slow clock
*/
bic tmp1, tmp1, #AT91_PMC_CSS
str tmp1, [pmc, #AT91_PMC_MCKR]
wait_mckrdy
#ifdef SLOWDOWN_MASTER_CLOCK
/*
* Set the Master Clock PRES and MDIV fields.
*
* See AT91RM9200 errata #27 and #28 for details.
*/
mov tmp1, #0
str tmp1, [pmc, #AT91_PMC_MCKR]
wait_mckrdy
#endif
/* Save PLLA setting and disable it */
ldr tmp1, [pmc, #AT91_CKGR_PLLAR]
str tmp1, .saved_pllar
mov tmp1, #AT91_PMC_PLLCOUNT
orr tmp1, tmp1, #(1 << 29) /* bit 29 always set */
str tmp1, [pmc, #AT91_CKGR_PLLAR]
/* Save PLLB setting and disable it */
ldr tmp1, [pmc, #AT91_CKGR_PLLBR]
str tmp1, .saved_pllbr
mov tmp1, #AT91_PMC_PLLCOUNT
str tmp1, [pmc, #AT91_CKGR_PLLBR]
/* Turn off the main oscillator */
ldr tmp1, [pmc, #AT91_CKGR_MOR]
bic tmp1, tmp1, #AT91_PMC_MOSCEN
str tmp1, [pmc, #AT91_CKGR_MOR]
/* Wait for interrupt */
mcr p15, 0, tmp1, c7, c0, 4
/* Turn on the main oscillator */
ldr tmp1, [pmc, #AT91_CKGR_MOR]
orr tmp1, tmp1, #AT91_PMC_MOSCEN
str tmp1, [pmc, #AT91_CKGR_MOR]
wait_moscrdy
/* Restore PLLB setting */
ldr tmp1, .saved_pllbr
str tmp1, [pmc, #AT91_CKGR_PLLBR]
tst tmp1, #(AT91_PMC_MUL & 0xff0000)
bne 1f
tst tmp1, #(AT91_PMC_MUL & ~0xff0000)
beq 2f
1:
wait_pllblock
2:
/* Restore PLLA setting */
ldr tmp1, .saved_pllar
str tmp1, [pmc, #AT91_CKGR_PLLAR]
tst tmp1, #(AT91_PMC_MUL & 0xff0000)
bne 3f
tst tmp1, #(AT91_PMC_MUL & ~0xff0000)
beq 4f
3:
wait_pllalock
4:
#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 tmp1, .saved_mckr
tst tmp1, #AT91_PMC_PRES
beq 2f
and tmp1, tmp1, #AT91_PMC_PRES
str tmp1, [pmc, #AT91_PMC_MCKR]
wait_mckrdy
#endif
/*
* Restore master clock setting
*/
2: ldr tmp1, .saved_mckr
str tmp1, [pmc, #AT91_PMC_MCKR]
wait_mckrdy
/*
* at91rm9200 Memory controller
* Do nothing - self-refresh is automatically disabled.
*/
cmp memctrl, #AT91_MEMCTRL_MC
beq ram_restored
/*
* DDRSDR Memory controller
*/
cmp memctrl, #AT91_MEMCTRL_DDRSDR
bne sdr_en_restore
/* Restore LPR on AT91 with DDRAM */
ldr tmp1, .saved_sam9_lpr
str tmp1, [sdramc, #AT91_DDRSDRC_LPR]
/* if we use the second ram controller */
cmp ramc1, #0
ldrne tmp2, .saved_sam9_lpr1
strne tmp2, [ramc1, #AT91_DDRSDRC_LPR]
b ram_restored
/*
* SDRAMC Memory controller
*/
sdr_en_restore:
/* Restore LPR on AT91 with SDRAM */
ldr tmp1, .saved_sam9_lpr
str tmp1, [sdramc, #AT91_SDRAMC_LPR]
ram_restored:
/* Restore registers, and return */
ldmfd sp!, {r4 - r12, pc}
.saved_mckr:
.word 0
.saved_pllar:
.word 0
.saved_pllbr:
.word 0
.saved_sam9_lpr:
.word 0
.saved_sam9_lpr1:
.word 0
ENTRY(at91_slow_clock_sz)
.word .-at91_slow_clock
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