78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/*
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* (C) Copyright 2014
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* Heiko Schocher, DENX Software Engineering, hs@denx.de.
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*
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* Based on:
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* (C) Copyright 2007-2008
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* Stelian Pop <stelian@popies.net>
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* Lead Tech Design <www.leadtechdesign.com>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/arch/at91_common.h>
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#include <asm/arch/at91_pmc.h>
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#include <asm/arch/at91sam9_sdramc.h>
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#include <asm/arch/gpio.h>
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int sdramc_initialize(unsigned int sdram_address, const struct sdramc_reg *p)
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{
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struct sdramc_reg *reg = (struct sdramc_reg *)ATMEL_BASE_SDRAMC;
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unsigned int i;
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/* SDRAM feature must be in the configuration register */
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writel(p->cr, ®->cr);
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/* The SDRAM memory type must be set in the Memory Device Register */
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writel(p->mdr, ®->mdr);
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/*
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* The minimum pause of 200 us is provided to precede any single
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* toggle
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*/
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for (i = 0; i < 1000; i++)
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;
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/* A NOP command is issued to the SDRAM devices */
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writel(AT91_SDRAMC_MODE_NOP, ®->mr);
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writel(0x00000000, sdram_address);
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/* An All Banks Precharge command is issued to the SDRAM devices */
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writel(AT91_SDRAMC_MODE_PRECHARGE, ®->mr);
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writel(0x00000000, sdram_address);
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for (i = 0; i < 10000; i++)
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;
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/* Eight auto-refresh cycles are provided */
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for (i = 0; i < 8; i++) {
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writel(AT91_SDRAMC_MODE_REFRESH, ®->mr);
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writel(0x00000001 + i, sdram_address + 4 + 4 * i);
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}
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/*
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* A Mode Register set (MRS) cyscle is issued to program the
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* SDRAM parameters(TCSR, PASR, DS)
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*/
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writel(AT91_SDRAMC_MODE_LMR, ®->mr);
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writel(0xcafedede, sdram_address + 0x24);
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/*
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* The application must go into Normal Mode, setting Mode
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* to 0 in the Mode Register and perform a write access at
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* any location in the SDRAM.
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*/
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writel(AT91_SDRAMC_MODE_NORMAL, ®->mr);
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writel(0x00000000, sdram_address); /* Perform Normal mode */
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/*
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* Write the refresh rate into the count field in the SDRAMC
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* Refresh Timer Rgister.
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*/
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writel(p->tr, ®->tr);
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return 0;
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}
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