/* SPDX-License-Identifier: GPL-2.0-only */
/*
* arch/arm/mach-lpc32xx/suspend.S
*
* Original authors: Dmitry Chigirev, Vitaly Wool <[email protected]>
* Modified by Kevin Wells <[email protected]>
*
* 2005 (c) MontaVista Software, Inc.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include "lpc32xx.h"
/* Using named register defines makes the code easier to follow */
#define WORK1_REG r0
#define WORK2_REG r1
#define SAVED_HCLK_DIV_REG r2
#define SAVED_HCLK_PLL_REG r3
#define SAVED_DRAM_CLKCTRL_REG r4
#define SAVED_PWR_CTRL_REG r5
#define CLKPWRBASE_REG r6
#define EMCBASE_REG r7
#define LPC32XX_EMC_STATUS_OFFS 0x04
#define LPC32XX_EMC_STATUS_BUSY 0x1
#define LPC32XX_EMC_STATUS_SELF_RFSH 0x4
#define LPC32XX_CLKPWR_PWR_CTRL_OFFS 0x44
#define LPC32XX_CLKPWR_HCLK_DIV_OFFS 0x40
#define LPC32XX_CLKPWR_HCLKPLL_CTRL_OFFS 0x58
#define CLKPWR_PCLK_DIV_MASK 0xFFFFFE7F
.text
ENTRY(lpc32xx_sys_suspend)
@ Save a copy of the used registers in IRAM, r0 is corrupted
adr r0, tmp_stack_end
stmfd r0!, {r3 - r7, sp, lr}
@ Load a few common register addresses
adr WORK1_REG, reg_bases
ldr CLKPWRBASE_REG, [WORK1_REG, #0]
ldr EMCBASE_REG, [WORK1_REG, #4]
ldr SAVED_PWR_CTRL_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_PWR_CTRL_OFFS]
orr WORK1_REG, SAVED_PWR_CTRL_REG, #LPC32XX_CLKPWR_SDRAM_SELF_RFSH
@ Wait for SDRAM busy status to go busy and then idle
@ This guarantees a small windows where DRAM isn't busy
1:
ldr WORK2_REG, [EMCBASE_REG, #LPC32XX_EMC_STATUS_OFFS]
and WORK2_REG, WORK2_REG, #LPC32XX_EMC_STATUS_BUSY
cmp WORK2_REG, #LPC32XX_EMC_STATUS_BUSY
bne 1b @ Branch while idle
2:
ldr WORK2_REG, [EMCBASE_REG, #LPC32XX_EMC_STATUS_OFFS]
and WORK2_REG, WORK2_REG, #LPC32XX_EMC_STATUS_BUSY
cmp WORK2_REG, #LPC32XX_EMC_STATUS_BUSY
beq 2b @ Branch until idle
@ Setup self-refresh with support for manual exit of
@ self-refresh mode
str WORK1_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
orr WORK2_REG, WORK1_REG, #LPC32XX_CLKPWR_UPD_SDRAM_SELF_RFSH
str WORK2_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
str WORK1_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
@ Wait for self-refresh acknowledge, clocks to the DRAM device
@ will automatically stop on start of self-refresh
3:
ldr WORK2_REG, [EMCBASE_REG, #LPC32XX_EMC_STATUS_OFFS]
and WORK2_REG, WORK2_REG, #LPC32XX_EMC_STATUS_SELF_RFSH
cmp WORK2_REG, #LPC32XX_EMC_STATUS_SELF_RFSH
bne 3b @ Branch until self-refresh mode starts
@ Enter direct-run mode from run mode
bic WORK1_REG, WORK1_REG, #LPC32XX_CLKPWR_SELECT_RUN_MODE
str WORK1_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
@ Safe disable of DRAM clock in EMC block, prevents DDR sync
@ issues on restart
ldr SAVED_HCLK_DIV_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_HCLK_DIV_OFFS]
and WORK2_REG, SAVED_HCLK_DIV_REG, #CLKPWR_PCLK_DIV_MASK
str WORK2_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_HCLK_DIV_OFFS]
@ Save HCLK PLL state and disable HCLK PLL
ldr SAVED_HCLK_PLL_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_HCLKPLL_CTRL_OFFS]
bic WORK2_REG, SAVED_HCLK_PLL_REG, #LPC32XX_CLKPWR_HCLKPLL_POWER_UP
str WORK2_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_HCLKPLL_CTRL_OFFS]
@ Enter stop mode until an enabled event occurs
orr WORK1_REG, WORK1_REG, #LPC32XX_CLKPWR_STOP_MODE_CTRL
str WORK1_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
.rept 9
nop
.endr
@ Clear stop status
bic WORK1_REG, WORK1_REG, #LPC32XX_CLKPWR_STOP_MODE_CTRL
@ Restore original HCLK PLL value and wait for PLL lock
str SAVED_HCLK_PLL_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_HCLKPLL_CTRL_OFFS]
4:
ldr WORK2_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_HCLKPLL_CTRL_OFFS]
and WORK2_REG, WORK2_REG, #LPC32XX_CLKPWR_HCLKPLL_PLL_STS
bne 4b
@ Re-enter run mode with self-refresh flag cleared, but no DRAM
@ update yet. DRAM is still in self-refresh
str SAVED_PWR_CTRL_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_PWR_CTRL_OFFS]
@ Restore original DRAM clock mode to restore DRAM clocks
str SAVED_HCLK_DIV_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_HCLK_DIV_OFFS]
@ Clear self-refresh mode
orr WORK1_REG, SAVED_PWR_CTRL_REG,\
#LPC32XX_CLKPWR_UPD_SDRAM_SELF_RFSH
str WORK1_REG, [CLKPWRBASE_REG, #LPC32XX_CLKPWR_PWR_CTRL_OFFS]
str SAVED_PWR_CTRL_REG, [CLKPWRBASE_REG,\
#LPC32XX_CLKPWR_PWR_CTRL_OFFS]
@ Wait for EMC to clear self-refresh mode
5:
ldr WORK2_REG, [EMCBASE_REG, #LPC32XX_EMC_STATUS_OFFS]
and WORK2_REG, WORK2_REG, #LPC32XX_EMC_STATUS_SELF_RFSH
bne 5b @ Branch until self-refresh has exited
@ restore regs and return
adr r0, tmp_stack
ldmfd r0!, {r3 - r7, sp, pc}
reg_bases:
.long IO_ADDRESS(LPC32XX_CLK_PM_BASE)
.long IO_ADDRESS(LPC32XX_EMC_BASE)
tmp_stack:
.long 0, 0, 0, 0, 0, 0, 0
tmp_stack_end:
ENTRY(lpc32xx_sys_suspend_sz)
.word . - lpc32xx_sys_suspend
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