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136 lines
3.6 KiB
136 lines
3.6 KiB
/* |
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* Copyright (C) 2014-2015 Altera Corporation. All rights reserved. |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* under the terms and conditions of the GNU General Public License, |
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* version 2, as published by the Free Software Foundation. |
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* |
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* This program is distributed in the hope it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
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* more details. |
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* |
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* You should have received a copy of the GNU General Public License along with |
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* this program. If not, see <http://www.gnu.org/licenses/>. |
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*/ |
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#include <linux/linkage.h> |
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#include <asm/assembler.h> |
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#define MAX_LOOP_COUNT 1000 |
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/* Register offset */ |
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#define SDR_CTRLGRP_LOWPWREQ_ADDR 0x54 |
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#define SDR_CTRLGRP_LOWPWRACK_ADDR 0x58 |
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/* Bitfield positions */ |
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#define SELFRSHREQ_POS 3 |
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#define SELFRSHREQ_MASK 0x8 |
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#define SELFRFSHACK_POS 1 |
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#define SELFRFSHACK_MASK 0x2 |
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/* |
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* This code assumes that when the bootloader configured |
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* the sdram controller for the DDR on the board it |
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* configured the following fields depending on the DDR |
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* vendor/configuration: |
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* |
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* sdr.ctrlcfg.lowpwreq.selfrfshmask |
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* sdr.ctrlcfg.lowpwrtiming.clkdisablecycles |
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* sdr.ctrlcfg.dramtiming4.selfrfshexit |
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*/ |
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.arch armv7-a |
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.text |
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.align 3 |
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/* |
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* socfpga_sdram_self_refresh |
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* |
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* r0 : sdr_ctl_base_addr |
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* r1 : temp storage of return value |
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* r2 : temp storage of register values |
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* r3 : loop counter |
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* |
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* return value: lower 16 bits: loop count going into self refresh |
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* upper 16 bits: loop count exiting self refresh |
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*/ |
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ENTRY(socfpga_sdram_self_refresh) |
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/* Enable dynamic clock gating in the Power Control Register. */ |
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mrc p15, 0, r2, c15, c0, 0 |
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orr r2, r2, #1 |
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mcr p15, 0, r2, c15, c0, 0 |
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/* Enable self refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 1 */ |
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ldr r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] |
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orr r2, r2, #SELFRSHREQ_MASK |
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str r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] |
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/* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 1 or hit max loops */ |
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mov r3, #0 |
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while_ack_0: |
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ldr r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR] |
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and r2, r2, #SELFRFSHACK_MASK |
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cmp r2, #SELFRFSHACK_MASK |
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beq ack_1 |
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add r3, #1 |
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cmp r3, #MAX_LOOP_COUNT |
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bne while_ack_0 |
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ack_1: |
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mov r1, r3 |
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/* |
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* Execute an ISB instruction to ensure that all of the |
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* CP15 register changes have been committed. |
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*/ |
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isb |
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/* |
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* Execute a barrier instruction to ensure that all cache, |
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* TLB and branch predictor maintenance operations issued |
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* by any CPU in the cluster have completed. |
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*/ |
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dsb |
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dmb |
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wfi |
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/* Disable self-refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 0 */ |
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ldr r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] |
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bic r2, r2, #SELFRSHREQ_MASK |
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str r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR] |
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/* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 0 or hit max loops */ |
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mov r3, #0 |
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while_ack_1: |
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ldr r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR] |
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and r2, r2, #SELFRFSHACK_MASK |
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cmp r2, #SELFRFSHACK_MASK |
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bne ack_0 |
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add r3, #1 |
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cmp r3, #MAX_LOOP_COUNT |
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bne while_ack_1 |
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ack_0: |
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/* |
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* Prepare return value: |
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* Shift loop count for exiting self refresh into upper 16 bits. |
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* Leave loop count for requesting self refresh in lower 16 bits. |
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*/ |
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mov r3, r3, lsl #16 |
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add r1, r1, r3 |
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/* Disable dynamic clock gating in the Power Control Register. */ |
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mrc p15, 0, r2, c15, c0, 0 |
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bic r2, r2, #1 |
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mcr p15, 0, r2, c15, c0, 0 |
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mov r0, r1 @ return value |
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bx lr @ return |
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ENDPROC(socfpga_sdram_self_refresh) |
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ENTRY(socfpga_sdram_self_refresh_sz) |
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.word . - socfpga_sdram_self_refresh
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