diff options
Diffstat (limited to 'kernel/arch/arm/mach-socfpga/self-refresh.S')
| -rw-r--r-- | kernel/arch/arm/mach-socfpga/self-refresh.S | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/kernel/arch/arm/mach-socfpga/self-refresh.S b/kernel/arch/arm/mach-socfpga/self-refresh.S new file mode 100644 index 000000000..f2d7f883e --- /dev/null +++ b/kernel/arch/arm/mach-socfpga/self-refresh.S @@ -0,0 +1,136 @@ +/* + * Copyright (C) 2014-2015 Altera Corporation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>. + */ +#include <linux/linkage.h> +#include <asm/assembler.h> + +#define MAX_LOOP_COUNT 1000 + +/* Register offset */ +#define SDR_CTRLGRP_LOWPWREQ_ADDR 0x54 +#define SDR_CTRLGRP_LOWPWRACK_ADDR 0x58 + +/* Bitfield positions */ +#define SELFRSHREQ_POS 3 +#define SELFRSHREQ_MASK 0x8 + +#define SELFRFSHACK_POS 1 +#define SELFRFSHACK_MASK 0x2 + + /* + * This code assumes that when the bootloader configured + * the sdram controller for the DDR on the board it + * configured the following fields depending on the DDR + * vendor/configuration: + * + * sdr.ctrlcfg.lowpwreq.selfrfshmask + * sdr.ctrlcfg.lowpwrtiming.clkdisablecycles + * sdr.ctrlcfg.dramtiming4.selfrfshexit + */ + + .arch armv7-a + .text + .align 3 + + /* + * socfpga_sdram_self_refresh + * + * r0 : sdr_ctl_base_addr + * r1 : temp storage of return value + * r2 : temp storage of register values + * r3 : loop counter + * + * return value: lower 16 bits: loop count going into self refresh + * upper 16 bits: loop count exiting self refresh + */ +ENTRY(socfpga_sdram_self_refresh) + /* Enable dynamic clock gating in the Power Control Register. */ + mrc p15, 0, r2, c15, c0, 0 + orr r2, r2, #1 + mcr p15, 0, r2, c15, c0, 0 + + /* Enable self refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 1 */ + ldr r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] + orr r2, r2, #SELFRSHREQ_MASK + str r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] + + /* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 1 or hit max loops */ + mov r3, #0 +while_ack_0: + ldr r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR] + and r2, r2, #SELFRFSHACK_MASK + cmp r2, #SELFRFSHACK_MASK + beq ack_1 + + add r3, #1 + cmp r3, #MAX_LOOP_COUNT + bne while_ack_0 + +ack_1: + mov r1, r3 + + /* + * 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 + * by any CPU in the cluster have completed. + */ + dsb + dmb + + wfi + + /* Disable self-refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 0 */ + ldr r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] + bic r2, r2, #SELFRSHREQ_MASK + str r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] + + /* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 0 or hit max loops */ + mov r3, #0 +while_ack_1: + ldr r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR] + and r2, r2, #SELFRFSHACK_MASK + cmp r2, #SELFRFSHACK_MASK + bne ack_0 + + add r3, #1 + cmp r3, #MAX_LOOP_COUNT + bne while_ack_1 + +ack_0: + /* + * Prepare return value: + * Shift loop count for exiting self refresh into upper 16 bits. + * Leave loop count for requesting self refresh in lower 16 bits. + */ + mov r3, r3, lsl #16 + add r1, r1, r3 + + /* Disable dynamic clock gating in the Power Control Register. */ + mrc p15, 0, r2, c15, c0, 0 + bic r2, r2, #1 + mcr p15, 0, r2, c15, c0, 0 + + mov r0, r1 @ return value + bx lr @ return + +ENDPROC(socfpga_sdram_self_refresh) +ENTRY(socfpga_sdram_self_refresh_sz) + .word . - socfpga_sdram_self_refresh |