In preparation for suspend-resume support for AM33XX, add the assembly file with the code which is copied to internal memory (OCMC RAM) during bootup and runs from there. As part of the low power entry (DeepSleep0 mode in AM33XX TRM), the code running from OCMC RAM does the following 1. Calls routine to store the EMIF configuration 2. Calls routine to place external memory in self-refresh 3. Disables EMIF clock 4. Executes WFI after writing to MPU_CLKCTRL register. If no interrupts have come, WFI execution on MPU gets registered as an interrupt with the WKUP-M3. WKUP-M3 takes care of disabling some clocks which MPU should not (L3, L4, OCMC RAM etc) and takes care of clockdomain and powerdomain transitions as part of the DeepSleep0 mode entry. In case a late interrupt comes in, WFI ends up as a NOP and MPU continues execution from internal memory. The 'abort path' code undoes whatever was done as part of the low power entry and indicates a suspend failure by passing a non-zero value to the cpu_resume routine. The 'resume path' code is similar to the 'abort path' with the key difference of MMU being enabled in the 'abort path' but being disabled in the 'resume path' due to MPU getting powered off. Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx> --- arch/arm/mach-omap2/sleep33xx.S | 216 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 216 insertions(+) create mode 100644 arch/arm/mach-omap2/sleep33xx.S diff --git a/arch/arm/mach-omap2/sleep33xx.S b/arch/arm/mach-omap2/sleep33xx.S new file mode 100644 index 0000000..9399a16 --- /dev/null +++ b/arch/arm/mach-omap2/sleep33xx.S @@ -0,0 +1,216 @@ +/* + * Low level suspend code for AM33XX SoCs + * + * Copyright (C) 2012-2014 Texas Instruments Incorporated - http://www.ti.com/ + * Vaibhav Bedia, Dave Gerlach + * + * 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 version 2. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/linkage.h> +#include <asm/memory.h> +#include <asm/assembler.h> + +#include "iomap.h" +#include "cm33xx.h" + +#define AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE 0x0003 +#define AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE 0x0002 + + .text + .align 3 + +ENTRY(am33xx_do_wfi) + stmfd sp!, {r4 - r11, lr} @ save registers on stack + + /* + * Flush all data from the L1 and L2 data cache before disabling + * SCTLR.C bit. + */ + ldr r1, kernel_flush + blx r1 + + /* + * Clear the SCTLR.C bit to prevent further data cache + * allocation. Clearing SCTLR.C would make all the data accesses + * strongly ordered and would not hit the cache. + */ + mrc p15, 0, r0, c1, c0, 0 + bic r0, r0, #(1 << 2) @ Disable the C bit + mcr p15, 0, r0, c1, c0, 0 + isb + + /* + * Invalidate L1 and L2 data cache. + */ + ldr r1, kernel_flush + blx r1 + + ldr r1, ti_emif_save_context + blx r1 + + ldr r1, ti_emif_enter_sr + blx r1 + + /* Disable EMIF */ + ldr r1, virt_emif_clkctrl + ldr r2, [r1] + bic r2, r2, #AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE + str r2, [r1] + + ldr r1, virt_emif_clkctrl +wait_emif_disable: + ldr r2, [r1] + ldr r3, module_disabled_val + cmp r2, r3 + bne wait_emif_disable + + /* + * For the MPU WFI to be registered as an interrupt + * to WKUP_M3, MPU_CLKCTRL.MODULEMODE needs to be set + * to DISABLED + */ + ldr r1, virt_mpu_clkctrl + ldr r2, [r1] + bic r2, r2, #AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE + str r2, [r1] + + /* + * Execute an ISB instruction to ensure that all of the + * CP15 register changes have been committed. + */ + isb + + /* + * Execute a barrier instruction to ensure that all cache, + * TLB and branch predictor maintenance operations issued + * have completed. + */ + dsb + dmb + + /* + * Execute a WFI instruction and wait until the + * STANDBYWFI output is asserted to indicate that the + * CPU is in idle and low power state. CPU can specualatively + * prefetch the instructions so add NOPs after WFI. Thirteen + * NOPs as per Cortex-A8 pipeline. + */ + wfi + + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + + /* We come here in case of an abort due to a late interrupt */ + + /* Set MPU_CLKCTRL.MODULEMODE back to ENABLE */ + ldr r1, virt_mpu_clkctrl + mov r2, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE + str r2, [r1] + + /* Re-enable EMIF */ + ldr r1, virt_emif_clkctrl + mov r2, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE + str r2, [r1] +wait_emif_enable: + ldr r3, [r1] + cmp r2, r3 + bne wait_emif_enable + + ldr r1, ti_emif_abort_sr + blx r1 + + /* + * Set SCTLR.C bit to allow data cache allocation + */ + mrc p15, 0, r0, c1, c0, 0 + orr r0, r0, #(1 << 2) @ Enable the C bit + mcr p15, 0, r0, c1, c0, 0 + isb + + /* Let the suspend code know about the abort */ + mov r0, #1 + ldmfd sp!, {r4 - r11, pc} @ restore regs and return +ENDPROC(am33xx_do_wfi) + + .align +ENTRY(am33xx_resume_offset) + .word . - am33xx_do_wfi + +ENTRY(am33xx_resume_from_deep_sleep) + /* Re-enable EMIF */ + ldr r0, phys_emif_clkctrl + mov r1, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE + str r1, [r0] +wait_emif_enable1: + ldr r2, [r0] + cmp r1, r2 + bne wait_emif_enable1 + + adr sp, temp_stack + + ldr r1, ti_emif_restore_context + blx r1 + + ldr r1, ti_emif_exit_sr + blx r1 + +resume_to_ddr: + /* We are back. Branch to the common CPU resume routine */ + mov r0, #0 + ldr pc, resume_addr +ENDPROC(am33xx_resume_from_deep_sleep) + +/* + * Local variables + */ + .align +resume_addr: + .word cpu_resume - PAGE_OFFSET + 0x80000000 +kernel_flush: + .word v7_flush_dcache_all +virt_mpu_clkctrl: + .word AM33XX_CM_MPU_MPU_CLKCTRL +virt_emif_clkctrl: + .word AM33XX_CM_PER_EMIF_CLKCTRL +phys_emif_clkctrl: + .word (AM33XX_CM_BASE + AM33XX_CM_PER_MOD + \ + AM33XX_CM_PER_EMIF_CLKCTRL_OFFSET) +module_disabled_val: + .word 0x30000 + +/* DDR related defines */ +ENTRY(am33xx_emif_sram_table) +ti_emif_save_context: + .word 0x00000000 +ti_emif_restore_context: + .word 0x00000000 +ti_emif_enter_sr: + .word 0x00000000 +ti_emif_exit_sr: + .word 0x00000000 +ti_emif_abort_sr: + .word 0x00000000 + .align 3 + .space 64 +temp_stack: +ENTRY(am33xx_do_wfi_sz) + .word . - am33xx_do_wfi -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
