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Diffstat (limited to 'arch/avr32/cpu/hsdramc.c')
-rw-r--r-- | arch/avr32/cpu/hsdramc.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/arch/avr32/cpu/hsdramc.c b/arch/avr32/cpu/hsdramc.c new file mode 100644 index 0000000..b6eae66 --- /dev/null +++ b/arch/avr32/cpu/hsdramc.c @@ -0,0 +1,117 @@ +/* + * Copyright (C) 2005-2006 Atmel Corporation + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ +#include <common.h> + +#include <asm/io.h> +#include <asm/sdram.h> + +#include <asm/arch/clk.h> +#include <asm/arch/memory-map.h> + +#include "hsdramc1.h" + +unsigned long sdram_init(void *sdram_base, const struct sdram_config *config) +{ + unsigned long sdram_size; + uint32_t cfgreg; + unsigned int i; + + cfgreg = (HSDRAMC1_BF(NC, config->col_bits - 8) + | HSDRAMC1_BF(NR, config->row_bits - 11) + | HSDRAMC1_BF(NB, config->bank_bits - 1) + | HSDRAMC1_BF(CAS, config->cas) + | HSDRAMC1_BF(TWR, config->twr) + | HSDRAMC1_BF(TRC, config->trc) + | HSDRAMC1_BF(TRP, config->trp) + | HSDRAMC1_BF(TRCD, config->trcd) + | HSDRAMC1_BF(TRAS, config->tras) + | HSDRAMC1_BF(TXSR, config->txsr)); + + if (config->data_bits == SDRAM_DATA_16BIT) + cfgreg |= HSDRAMC1_BIT(DBW); + + hsdramc1_writel(CR, cfgreg); + + /* Send a NOP to turn on the clock (necessary on some chips) */ + hsdramc1_writel(MR, HSDRAMC1_MODE_NOP); + hsdramc1_readl(MR); + writel(0, sdram_base); + + /* + * Initialization sequence for SDRAM, from the data sheet: + * + * 1. A minimum pause of 200 us is provided to precede any + * signal toggle. + */ + udelay(200); + + /* + * 2. A Precharge All command is issued to the SDRAM + */ + hsdramc1_writel(MR, HSDRAMC1_MODE_BANKS_PRECHARGE); + hsdramc1_readl(MR); + writel(0, sdram_base); + + /* + * 3. Eight auto-refresh (CBR) cycles are provided + */ + hsdramc1_writel(MR, HSDRAMC1_MODE_AUTO_REFRESH); + hsdramc1_readl(MR); + for (i = 0; i < 8; i++) + writel(0, sdram_base); + + /* + * 4. A mode register set (MRS) cycle is issued to program + * SDRAM parameters, in particular CAS latency and burst + * length. + * + * The address will be chosen by the SDRAMC automatically; we + * just have to make sure BA[1:0] are set to 0. + */ + hsdramc1_writel(MR, HSDRAMC1_MODE_LOAD_MODE); + hsdramc1_readl(MR); + writel(0, sdram_base); + + /* + * 5. The application must go into Normal Mode, setting Mode + * to 0 in the Mode Register and performing a write access + * at any location in the SDRAM. + */ + hsdramc1_writel(MR, HSDRAMC1_MODE_NORMAL); + hsdramc1_readl(MR); + writel(0, sdram_base); + + /* + * 6. Write refresh rate into SDRAMC refresh timer count + * register (refresh rate = timing between refresh cycles). + */ + hsdramc1_writel(TR, config->refresh_period); + + if (config->data_bits == SDRAM_DATA_16BIT) + sdram_size = 1 << (config->row_bits + config->col_bits + + config->bank_bits + 1); + else + sdram_size = 1 << (config->row_bits + config->col_bits + + config->bank_bits + 2); + + return sdram_size; +} |