diff options
Diffstat (limited to 'arch/arm/mach-imx/imx7d_low_power_idle.S')
| -rw-r--r-- | arch/arm/mach-imx/imx7d_low_power_idle.S | 787 |
1 files changed, 787 insertions, 0 deletions
diff --git a/arch/arm/mach-imx/imx7d_low_power_idle.S b/arch/arm/mach-imx/imx7d_low_power_idle.S new file mode 100644 index 000000000000..1551d2ce1acf --- /dev/null +++ b/arch/arm/mach-imx/imx7d_low_power_idle.S @@ -0,0 +1,787 @@ +/* + * Copyright (C) 2015 Freescale Semiconductor, Inc. All Rights Reserved. + * + * 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. + */ + +#include <linux/linkage.h> + +#define PM_INFO_VBASE_OFFSET 0x0 +#define PM_INFO_PBASE_OFFSET 0x4 +#define PM_INFO_RESUME_ADDR_OFFSET 0x8 +#define PM_INFO_PM_INFO_SIZE_OFFSET 0xc +#define PM_INFO_PM_INFO_TTBR_OFFSET 0x10 +#define PM_INFO_PM_INFO_NUM_ONLINE_CPUS_OFFSET 0x14 +#define PM_INFO_PM_INFO_NUM_LPI_CPUS_OFFSET 0x18 +#define PM_INFO_VAL_OFFSET 0x1c +#define PM_INFO_FLAG0_OFFSET 0x20 +#define PM_INFO_FLAG1_OFFSET 0x24 +#define PM_INFO_MX7D_DDRC_P_OFFSET 0x28 +#define PM_INFO_MX7D_DDRC_V_OFFSET 0x2c +#define PM_INFO_MX7D_CCM_P_OFFSET 0x30 +#define PM_INFO_MX7D_CCM_V_OFFSET 0x34 +#define PM_INFO_MX7D_ANATOP_P_OFFSET 0x38 +#define PM_INFO_MX7D_ANATOP_V_OFFSET 0x3c +#define PM_INFO_MX7D_SRC_P_OFFSET 0x40 +#define PM_INFO_MX7D_SRC_V_OFFSET 0x44 +#define PM_INFO_MX7D_IOMUXC_GPR_P_OFFSET 0x48 +#define PM_INFO_MX7D_IOMUXC_GPR_V_OFFSET 0x4c +#define PM_INFO_MX7D_GPC_P_OFFSET 0x50 +#define PM_INFO_MX7D_GPC_V_OFFSET 0x54 +#define PM_INFO_MX7D_GIC_DIST_P_OFFSET 0x58 +#define PM_INFO_MX7D_GIC_DIST_V_OFFSET 0x5c + +#define MX7D_SRC_GPR1 0x74 +#define MX7D_SRC_GPR2 0x78 +#define MX7D_SRC_GPR3 0x7c +#define MX7D_SRC_GPR4 0x80 +#define MX7D_GPC_IMR1 0x30 +#define MX7D_GPC_IMR2 0x34 +#define MX7D_GPC_IMR3 0x38 +#define MX7D_GPC_IMR4 0x3c +#define DDRC_STAT 0x4 +#define DDRC_PWRCTL 0x30 +#define DDRC_DBG1 0x304 +#define DDRC_DBGCAM 0x308 +#define DDRC_PSTAT 0x3fc +#define DDRC_PCTRL_0 0x490 + +/* + * imx_pen_lock + * + * The reference link of Peterson's algorithm: + * http://en.wikipedia.org/wiki/Peterson's_algorithm + * + * val1 = r1 = !turn (inverted from Peterson's algorithm) + * on cpu 0: + * r2 = flag[0] (in flag0) + * r3 = flag[1] (in flag1) + * on cpu1: + * r2 = flag[1] (in flag1) + * r3 = flag[0] (in flag0) + * + */ + .macro imx_pen_lock + + mov r8, r0 + mrc p15, 0, r5, c0, c0, 5 + and r5, r5, #3 + add r6, r8, #PM_INFO_VAL_OFFSET + cmp r5, #0 + addeq r7, r8, #PM_INFO_FLAG0_OFFSET + addeq r8, r8, #PM_INFO_FLAG1_OFFSET + addne r7, r8, #PM_INFO_FLAG1_OFFSET + addne r8, r8, #PM_INFO_FLAG0_OFFSET + + mov r9, #1 + str r9, [r7] + dsb + str r5, [r6] +1: + dsb + ldr r9, [r8] + cmp r9, #1 + ldreq r9, [r6] + cmpeq r9, r5 + beq 1b + + .endm + + .macro imx_pen_unlock + + dsb + mrc p15, 0, r6, c0, c0, 5 + and r6, r6, #3 + cmp r6, #0 + addeq r7, r0, #PM_INFO_FLAG0_OFFSET + addne r7, r0, #PM_INFO_FLAG1_OFFSET + mov r9, #0 + str r9, [r7] + + .endm + + .macro disable_l1_dcache + + push {r0 - r12, lr} + ldr r7, =v7_flush_dcache_all + mov lr, pc + mov pc, r7 + pop {r0 - r12, lr} + + /* disable d-cache */ + mrc p15, 0, r7, c1, c0, 0 + bic r7, r7, #(1 << 2) + mcr p15, 0, r7, c1, c0, 0 + dsb + isb + + push {r0 - r12, lr} + ldr r7, =v7_flush_dcache_all + mov lr, pc + mov pc, r7 + pop {r0 - r12, lr} + +#ifdef CONFIG_SMP + clrex + + /* Turn off SMP bit. */ + mrc p15, 0, r8, c1, c0, 1 + bic r8, r8, #0x40 + mcr p15, 0, r8, c1, c0, 1 + + isb + dsb +#endif + + .endm + + .macro tlb_set_to_ocram + + /* save ttbr */ + mrc p15, 0, r7, c2, c0, 1 + str r7, [r0, #PM_INFO_PM_INFO_TTBR_OFFSET] + + /* + * To ensure no page table walks occur in DDR, we + * have a another page table stored in IRAM that only + * contains entries pointing to IRAM, AIPS1 and AIPS2. + * We need to set the TTBR1 to the new IRAM TLB. + * Do the following steps: + * 1. Flush the Branch Target Address Cache (BTAC) + * 2. Set TTBR1 to point to IRAM page table. + * 3. Disable page table walks in TTBR0 (PD0 = 1) + * 4. Set TTBR0.N=1, implying 0-2G is translated by TTBR0 + * and 2-4G is translated by TTBR1. + */ + + /* Disable Branch Prediction, Z bit in SCTLR. */ + mrc p15, 0, r6, c1, c0, 0 + bic r6, r6, #0x800 + mcr p15, 0, r6, c1, c0, 0 + + /* Flush the BTAC. */ + ldr r6, =0x0 + mcr p15, 0, r6, c7, c1, 6 + + ldr r6, =iram_tlb_phys_addr + ldr r7, [r6] + + dsb + isb + + /* Store the IRAM table in TTBR1 */ + mcr p15, 0, r7, c2, c0, 1 + + /* Read TTBCR and set PD0=1, N = 1 */ + mrc p15, 0, r6, c2, c0, 2 + orr r6, r6, #0x11 + mcr p15, 0, r6, c2, c0, 2 + + dsb + isb + + /* flush the TLB */ + ldr r6, =0x0 + mcr p15, 0, r6, c8, c3, 0 + + .endm + + .macro tlb_back_to_ddr + + /* Read TTBCR and set PD0=0, N = 0 */ + mrc p15, 0, r6, c2, c0, 2 + bic r6, r6, #0x11 + mcr p15, 0, r6, c2, c0, 2 + + dsb + isb + + /* flush the TLB */ + ldr r6, =0x0 + mcr p15, 0, r6, c8, c3, 0 + + /* Enable Branch Prediction, Z bit in SCTLR. */ + mrc p15, 0, r6, c1, c0, 0 + orr r6, r6, #0x800 + mcr p15, 0, r6, c1, c0, 0 + + /* Flush the Branch Target Address Cache (BTAC) */ + ldr r6, =0x0 + mcr p15, 0, r6, c7, c1, 6 + + /* restore ttbr */ + ldr r7, [r0, #PM_INFO_PM_INFO_TTBR_OFFSET] + mcr p15, 0, r7, c2, c0, 1 + + .endm + + /* r10 must be DDRC base address */ + .macro ddrc_enter_self_refresh + + ldr r10, [r0, #PM_INFO_MX7D_DDRC_V_OFFSET] + + /* disable port */ + ldr r7, =0x0 + str r7, [r10, #DDRC_PCTRL_0] + + /* let DDR out of self-refresh */ + ldr r7, =0x0 + str r7, [r10, #DDRC_PWRCTL] + + /* wait rw port_busy clear */ + ldr r6, =(0x1 << 16) + orr r6, r6, #0x1 +2: + ldr r7, [r10, #DDRC_PSTAT] + ands r7, r7, r6 + bne 2b + + ldr r7, =0x1 + str r7, [r10, #DDRC_DBG1] + + ldr r6, =0x36000000 +11: + ldr r7, [r10, #DDRC_DBGCAM] + and r7, r7, r6 + cmp r7, r6 + bne 11b + + /* enter self-refresh bit 5 */ + ldr r7, =(0x1 << 5) + str r7, [r10, #DDRC_PWRCTL] + + /* wait until self-refresh mode entered */ +3: + ldr r7, [r10, #DDRC_STAT] + and r7, r7, #0x3 + cmp r7, #0x3 + bne 3b +4: + ldr r7, [r10, #DDRC_STAT] + ands r7, r7, #0x20 + beq 4b + + /* disable dram clk */ + ldr r7, [r10, #DDRC_PWRCTL] + orr r7, r7, #(1 << 3) + str r7, [r10, #DDRC_PWRCTL] + + /* + * TO1.1 adds feature of DDR pads power down, + * although TO1.0 has no such function, but it is + * NOT harmful to program GPR registers for TO1.0, + * it can avoid the logic of version check in idle + * thread. + */ + ldr r10, [r0, #PM_INFO_MX7D_IOMUXC_GPR_V_OFFSET] + ldr r7, =0xf0000 + str r7, [r10] + + /* delay 20us, measured by gpio */ + ldr r7, =20 +12: + subs r7, r7, #0x1 + bne 12b + + .endm + + /* r10 must be DDRC base address */ + .macro ddrc_exit_self_refresh + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_IOMUXC_GPR_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_IOMUXC_GPR_V_OFFSET] + + ldr r7, =0x0 + str r7, [r10] + + ldr r7, =20 +13: + subs r7, r7, #0x1 + bne 13b + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_DDRC_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_DDRC_V_OFFSET] + + ldr r7, =0x0 + str r7, [r10, #DDRC_DBG1] + + ldr r6, =0x30000000 +14: + ldr r7, [r10, #DDRC_DBGCAM] + and r7, r7, r6 + cmp r7, r6 + bne 14b + + /* let DDR out of self-refresh */ + ldr r7, =0x0 + str r7, [r10, #DDRC_PWRCTL] + + /* wait until self-refresh mode exited */ +5: + ldr r7, [r10, #DDRC_STAT] + and r7, r7, #0x3 + cmp r7, #0x3 + beq 5b + + /* enable auto self-refresh */ + ldr r7, [r10, #DDRC_PWRCTL] + orr r7, r7, #(1 << 0) + str r7, [r10, #DDRC_PWRCTL] + + ldr r7, =0x1 + str r7, [r10, #DDRC_PCTRL_0] + + .endm + + .macro pll_do_wait_lock +6: + ldr r7, [r10, r8] + ands r7, #0x80000000 + beq 6b + + .endm + + .macro ccm_enter_idle + + ldr r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* ungate pfd1 332m for lower axi */ + ldr r7, =0x8000 + str r7, [r10, #0xc8] + + ldr r10, [r0, #PM_INFO_MX7D_CCM_V_OFFSET] + + /* switch ARM CLK to OSC */ + ldr r8, =0x8000 + ldr r7, [r10, r8] + bic r7, r7, #0x7000000 + str r7, [r10, r8] + + /* lower AXI clk from 24MHz to 3MHz */ + ldr r8, =0x8800 + ldr r7, [r10, r8] + orr r7, r7, #0x7 + str r7, [r10, r8] + + /* lower AHB clk from 24MHz to 3MHz */ + ldr r8, =0x9000 + ldr r7, [r10, r8] + orr r7, r7, #0x7 + str r7, [r10, r8] + + /* gate dram clk */ + ldr r8, =0x9880 + ldr r7, [r10, r8] + bic r7, r7, #0x10000000 + str r7, [r10, r8] + + ldr r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* gate pfd1 332m */ + ldr r7, =0x8000 + str r7, [r10, #0xc4] + + /* gate system pll pfd div 1 */ + ldr r7, =0x10 + str r7, [r10, #0xb4] + /* power down ARM, 480 and DRAM PLL */ + ldr r7, =0x1000 + str r7, [r10, #0x64] + str r7, [r10, #0xb4] + ldr r7, =0x100000 + str r7, [r10, #0x74] + + .endm + + .macro ccm_exit_idle + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_ANATOP_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* power up ARM, 480 and DRAM PLL */ + ldr r7, =0x1000 + str r7, [r10, #0x68] + ldr r8, =0x60 + pll_do_wait_lock + + ldr r7, =0x1000 + str r7, [r10, #0xb8] + ldr r8, =0xb0 + pll_do_wait_lock + + ldr r7, =0x100000 + str r7, [r10, #0x78] + ldr r8, =0x70 + pll_do_wait_lock + + /* ungate pfd1 332m for lower axi */ + ldr r7, =0x8000 + str r7, [r10, #0xc8] + + /* ungate system pll pfd div 1 */ + ldr r7, =0x10 + str r7, [r10, #0xb8] + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_CCM_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_CCM_V_OFFSET] + + /* switch ARM CLK to PLL */ + ldr r8, =0x8000 + ldr r7, [r10, r8] + orr r7, r7, #0x1000000 + str r7, [r10, r8] + + /* restore AXI clk from 3MHz to 24MHz */ + ldr r8, =0x8800 + ldr r7, [r10, r8] + bic r7, r7, #0x7 + str r7, [r10, r8] + + /* restore AHB clk from 3MHz to 24MHz */ + ldr r8, =0x9000 + ldr r7, [r10, r8] + bic r7, r7, #0x7 + str r7, [r10, r8] + + /* ungate dram clk */ + ldr r8, =0x9880 + ldr r7, [r10, r8] + orr r7, r7, #0x10000000 + str r7, [r10, r8] + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_ANATOP_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* gate pfd1 332m for lower axi */ + ldr r7, =0x8000 + str r7, [r10, #0xc4] + + .endm + + .macro anatop_enter_idle + + ldr r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* XTAL to RC-OSC switch */ + ldr r7, [r10] + orr r7, r7, #0x1000 + str r7, [r10] + /* power down XTAL */ + ldr r7, [r10] + orr r7, r7, #0x1 + str r7, [r10] + + /* enable weak 1P0A */ + ldr r7, [r10, #0x200] + orr r7, r7, #0x40000 + str r7, [r10, #0x200] + + /* disable LDO 1P0A */ + ldr r7, [r10, #0x200] + bic r7, r7, #0x1 + str r7, [r10, #0x200] + + /* disable LDO 1P0D */ + ldr r7, [r10, #0x210] + bic r7, r7, #0x1 + str r7, [r10, #0x210] + + /* disable LDO 1P2 */ + ldr r7, [r10, #0x220] + bic r7, r7, #0x1 + str r7, [r10, #0x220] + + /* switch to low power bandgap */ + ldr r7, [r10, #0x270] + orr r7, r7, #0x400 + str r7, [r10, #0x270] + /* power down normal bandgap */ + orr r7, r7, #0x1 + str r7, [r10, #0x270] + + .endm + + .macro anatop_exit_idle + + cmp r5, #0x1 + ldreq r10, [r0, #PM_INFO_MX7D_ANATOP_P_OFFSET] + ldrne r10, [r0, #PM_INFO_MX7D_ANATOP_V_OFFSET] + + /* power on normal bandgap */ + ldr r7, [r10, #0x270] + bic r7, r7, #0x1 + str r7, [r10, #0x270] + /* switch to normal bandgap */ + bic r7, r7, #0x400 + str r7, [r10, #0x270] + + /* enable LDO 1P2 */ + ldr r7, [r10, #0x220] + orr r7, r7, #0x1 + str r7, [r10, #0x220] +7: + ldr r7, [r10, #0x220] + ands r7, #0x20000 + beq 7b + + /* enable LDO 1P0D */ + ldr r7, [r10, #0x210] + orr r7, r7, #0x1 + str r7, [r10, #0x210] +8: + ldr r7, [r10, #0x210] + ands r7, #0x20000 + beq 8b + + /* enable LDO 1P0A */ + ldr r7, [r10, #0x200] + orr r7, r7, #0x1 + str r7, [r10, #0x200] +9: + ldr r7, [r10, #0x200] + ands r7, #0x20000 + beq 9b + /* disable weak 1P0A */ + ldr r7, [r10, #0x200] + bic r7, r7, #0x40000 + str r7, [r10, #0x200] + + /* power up XTAL and wait */ + ldr r7, [r10] + bic r7, r7, #0x1 + str r7, [r10] +10: + ldr r7, [r10] + ands r7, r7, #0x4 + beq 10b + /* RC-OSC to XTAL switch */ + ldr r7, [r10] + bic r7, r7, #0x1000 + str r7, [r10] + + .endm + +.extern iram_tlb_phys_addr + + .align 3 +ENTRY(imx7d_low_power_idle) + push {r0 - r12} + + /* get necessary info from pm_info */ + ldr r1, [r0, #PM_INFO_PBASE_OFFSET] + ldr r2, [r0, #PM_INFO_PM_INFO_SIZE_OFFSET] + + /* + * counting the resume address in iram + * to set it in SRC register. + */ + ldr r5, =imx7d_low_power_idle + ldr r6, =wakeup + sub r6, r6, r5 + add r8, r1, r2 + add r3, r8, r6 + + /* r11 is cpu id */ + mrc p15, 0, r11, c0, c0, 5 + and r11, r11, #3 + cmp r11, #0x0 + ldreq r6, =MX7D_SRC_GPR1 + ldreq r7, =MX7D_SRC_GPR2 + ldrne r6, =MX7D_SRC_GPR3 + ldrne r7, =MX7D_SRC_GPR4 + /* store physical resume addr and pm_info address. */ + ldr r10, [r0, #PM_INFO_MX7D_SRC_V_OFFSET] + str r3, [r10, r6] + str r1, [r10, r7] + + disable_l1_dcache + + tlb_set_to_ocram + + /* check last to sleep */ + ldr r6, [r0, #PM_INFO_PM_INFO_NUM_ONLINE_CPUS_OFFSET] + ldr r7, [r0, #PM_INFO_PM_INFO_NUM_LPI_CPUS_OFFSET] + cmp r6, r7 + bne lpi_enter_done + + ddrc_enter_self_refresh + ccm_enter_idle + anatop_enter_idle + + ldr r10, [r0, #PM_INFO_MX7D_GIC_DIST_V_OFFSET] + ldr r7, =0x0 + ldr r8, =0x1000 + str r7, [r10, r8] + + ldr r10, [r0, #PM_INFO_MX7D_GPC_V_OFFSET] + ldr r4, [r10, #MX7D_GPC_IMR1] + ldr r5, [r10, #MX7D_GPC_IMR2] + ldr r6, [r10, #MX7D_GPC_IMR3] + ldr r7, [r10, #MX7D_GPC_IMR4] + + ldr r8, =0xffffffff + str r8, [r10, #MX7D_GPC_IMR1] + str r8, [r10, #MX7D_GPC_IMR2] + str r8, [r10, #MX7D_GPC_IMR3] + str r8, [r10, #MX7D_GPC_IMR4] + + /* + * enable the RBC bypass counter here + * to hold off the interrupts. RBC counter + * = 8 (240us). With this setting, the latency + * from wakeup interrupt to ARM power up + * is ~250uS. + */ + ldr r8, [r10, #0x14] + bic r8, r8, #(0x3f << 24) + orr r8, r8, #(0x8 << 24) + str r8, [r10, #0x14] + + /* enable the counter. */ + ldr r8, [r10, #0x14] + orr r8, r8, #(0x1 << 30) + str r8, [r10, #0x14] + + /* unmask all the GPC interrupts. */ + str r4, [r10, #MX7D_GPC_IMR1] + str r5, [r10, #MX7D_GPC_IMR2] + str r6, [r10, #MX7D_GPC_IMR3] + str r7, [r10, #MX7D_GPC_IMR4] + + /* + * now delay for a short while (30usec) + * ARM is at 24MHz at this point + * so a short loop should be enough. + * this delay is required to ensure that + * the RBC counter can start counting in + * case an interrupt is already pending + * or in case an interrupt arrives just + * as ARM is about to assert DSM_request. + */ + ldr r4, =5 +rbc_loop: + subs r4, r4, #0x1 + bne rbc_loop + +lpi_enter_done: + + imx_pen_unlock + + wfi + + nop + nop + nop + nop + nop + + nop + nop + nop + nop + nop + + nop + nop + nop + nop + nop + + nop + nop + nop + nop + nop + + nop + nop + nop + nop + nop + + imx_pen_lock + + /* check first to wake */ + ldr r6, [r0, #PM_INFO_PM_INFO_NUM_ONLINE_CPUS_OFFSET] + ldr r7, [r0, #PM_INFO_PM_INFO_NUM_LPI_CPUS_OFFSET] + cmp r6, r7 + bne skip_lpi_flow + + ldr r5, =0x0 + anatop_exit_idle + ccm_exit_idle + ddrc_exit_self_refresh + + ldr r10, [r0, #PM_INFO_MX7D_GIC_DIST_V_OFFSET] + ldr r7, =0x1 + ldr r8, =0x1000 + str r7, [r10, r8] + +skip_lpi_flow: + tlb_back_to_ddr + +#ifdef CONFIG_SMP + /* Turn on SMP bit. */ + mrc p15, 0, r7, c1, c0, 1 + orr r7, r7, #0x40 + mcr p15, 0, r7, c1, c0, 1 + + isb +#endif + + /* enable d-cache */ + mrc p15, 0, r7, c1, c0, 0 + orr r7, r7, #(1 << 2) + mcr p15, 0, r7, c1, c0, 0 + dsb + isb + + /* Restore registers */ + pop {r0 - r12} + mov pc, lr + +wakeup: + /* invalidate L1 I-cache first */ + mov r1, #0x0 + mcr p15, 0, r1, c7, c5, 0 + mcr p15, 0, r1, c7, c5, 0 + mcr p15, 0, r1, c7, c5, 6 + /* enable the Icache and branch prediction */ + mov r1, #0x1800 + mcr p15, 0, r1, c1, c0, 0 + isb + + imx_pen_lock + + /* check first to wake */ + ldr r6, [r0, #PM_INFO_PM_INFO_NUM_ONLINE_CPUS_OFFSET] + ldr r7, [r0, #PM_INFO_PM_INFO_NUM_LPI_CPUS_OFFSET] + cmp r6, r7 + bne wakeup_skip_lpi_flow + + ldr r5, =0x1 + anatop_exit_idle + ccm_exit_idle + ddrc_exit_self_refresh + +wakeup_skip_lpi_flow: + /* get physical resume address from pm_info. */ + ldr lr, [r0, #PM_INFO_RESUME_ADDR_OFFSET] + + /* Restore registers */ + mov pc, lr + .ltorg +ENDPROC(imx7d_low_power_idle) |