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kernel/linux-imx6_3.14.28/arch/arm/mach-omap2/sleep24xx.S 3.37 KB
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  /*
   * linux/arch/arm/mach-omap2/sleep.S
   *
   * (C) Copyright 2004
   * Texas Instruments, <www.ti.com>
   * Richard Woodruff <r-woodruff2@ti.com>
   *
   * (C) Copyright 2006 Nokia Corporation
   * Fixed idle loop sleep
   * Igor Stoppa <igor.stoppa@nokia.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of
   * the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
   * MA 02111-1307 USA
   */
  
  #include <linux/linkage.h>
  #include <asm/assembler.h>
  
  #include "omap24xx.h"
  #include "sdrc.h"
  
  /* First address of reserved address space?  apparently valid for OMAP2 & 3 */
  #define A_SDRC0_V		(0xC0000000)
  
  	.text
  
  /*
   * omap24xx_cpu_suspend() - Forces OMAP into deep sleep state by completing
   * SDRC shutdown then ARM shutdown.  Upon wake MPU is back on so just restore
   * SDRC.
   *
   * Input:
   * R0 :	DLL ctrl value pre-Sleep
   * R1 : SDRC_DLLA_CTRL
   * R2 : SDRC_POWER
   *
   * The if the DPLL is going to AutoIdle. It seems like the DPLL may be back on
   * when we get called, but the DLL probably isn't.  We will wait a bit more in
   * case the DPLL isn't quite there yet. The code will wait on DLL for DDR even
   * if in unlocked mode.
   *
   * For less than 242x-ES2.2 upon wake from a sleep mode where the external
   * oscillator was stopped, a timing bug exists where a non-stabilized 12MHz
   * clock can pass into the PRCM can cause problems at DSP and IVA.
   * To work around this the code will switch to the 32kHz source prior to sleep.
   * Post sleep we will shift back to using the DPLL.  Apparently,
   * CM_IDLEST_CLKGEN does not reflect the full clock change so you need to wait
   * 3x12MHz + 3x32kHz clocks for a full switch.
   *
   * The DLL load value is not kept in RETENTION or OFF.	It needs to be restored
   * at wake
   */
  	.align	3
  ENTRY(omap24xx_cpu_suspend)
  	stmfd	sp!, {r0 - r12, lr}	@ save registers on stack
  	mov	r3, #0x0		@ clear for mcr call
  	mcr	p15, 0, r3, c7, c10, 4	@ memory barrier, hope SDR/DDR finished
  	nop
  	nop
  	ldr	r4, [r2]		@ read SDRC_POWER
  	orr	r4, r4, #0x40		@ enable self refresh on idle req
  	mov	r5, #0x2000		@ set delay (DPLL relock + DLL relock)
  	str	r4, [r2]		@ make it so
  	nop
  	mcr	p15, 0, r3, c7, c0, 4	@ wait for interrupt
  	nop
  loop:
  	subs	r5, r5, #0x1		@ awake, wait just a bit
  	bne	loop
  
  	/* The DPLL has to be on before we take the DDR out of self refresh */
  	bic	r4, r4, #0x40		@ now clear self refresh bit.
  	str	r4, [r2]		@ write to SDRC_POWER
  	ldr	r4, A_SDRC0		@ make a clock happen
  	ldr	r4, [r4]		@ read A_SDRC0
  	nop				@ start auto refresh only after clk ok
  	movs	r0, r0			@ see if DDR or SDR
  	strne	r0, [r1]		@ rewrite DLLA to force DLL reload
  	addne	r1, r1, #0x8		@ move to DLLB
  	strne	r0, [r1]		@ rewrite DLLB to force DLL reload
  
  	mov	r5, #0x1000
  loop2:
  	subs	r5, r5, #0x1
  	bne	loop2
  	/* resume*/
  	ldmfd	sp!, {r0 - r12, pc}	@ restore regs and return
  
  A_SDRC0:
  	.word A_SDRC0_V
  
  ENTRY(omap24xx_cpu_suspend_sz)
  	.word	. - omap24xx_cpu_suspend