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kernel/linux-imx6_3.14.28/arch/arm/mach-lpc32xx/suspend.S 4.84 KB
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  /*
   * arch/arm/mach-lpc32xx/suspend.S
   *
   * Original authors: Dmitry Chigirev, Vitaly Wool <source@mvista.com>
   * Modified by Kevin Wells <kevin.wells@nxp.com>
   *
   * 2005 (c) MontaVista Software, Inc. This file is licensed under
   * the terms of the GNU General Public License version 2. This program
   * is licensed "as is" without any warranty of any kind, whether express
   * or implied.
   */
  #include <linux/linkage.h>
  #include <asm/assembler.h>
  #include <mach/platform.h>
  #include <mach/hardware.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