1 files changed, 141 insertions, 0 deletions
diff --git a/arch/arm/boards/edb93xx/sdram_cfg.c b/arch/arm/boards/edb93xx/sdram_cfg.c
new file mode 100644
index 0000000000..3d4fe08e19
--- /dev/null
+++ b/arch/arm/boards/edb93xx/sdram_cfg.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2009 Matthias Kaehlcke <matthias@kaehlcke.net>
+ *
+ * Copyright (C) 2006 Dominic Rath <Dominic.Rath@gmx.de>
+ *
+ * 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 "sdram_cfg.h"
+#include "early_udelay.h"
+
+#define PROGRAM_MODE_REG(bank)		(*(volatile uint32_t *)		\
+		(SDRAM_BASE_ADDR | SDRAM_BANK_SEL_##bank | SDRAM_MODE_REG_VAL))
+
+#define PRECHARGE_BANK(bank)		(*(volatile uint32_t *)	\
+		(SDRAM_BASE_ADDR | SDRAM_BANK_SEL_##bank)) = 0
+
+static void precharge_all_banks(void);
+static void setup_refresh_timer(void);
+static void program_mode_registers(void);
+
+void sdram_cfg(void)
+{
+	struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE;
+
+	writel(SDRAM_DEVCFG_VAL, &sdram->SDRAM_DEVCFG_REG);
+
+	/* Issue continous NOP commands */
+	writel(GLCONFIG_INIT | GLCONFIG_MRS | GLCONFIG_CKE, &sdram->glconfig);
+
+	early_udelay(200);
+
+	precharge_all_banks();
+
+	setup_refresh_timer();
+
+	program_mode_registers();
+
+	/* Select normal operation mode */
+	writel(GLCONFIG_CKE, &sdram->glconfig);
+}
+
+static void precharge_all_banks(void)
+{
+	struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE;
+
+	/* Issue PRECHARGE ALL commands */
+	writel(GLCONFIG_INIT | GLCONFIG_CKE, &sdram->glconfig);
+
+	/*
+	 * Errata of most EP93xx revisions say that PRECHARGE ALL isn't always
+	 * issued.
+	 *
+	 *  Cirrus proposes a workaround which consists in performing a read from
+	 * each bank to force the precharge. This causes some boards to hang.
+	 * Writing to the SDRAM banks instead of reading has the same
+	 * side-effect (the SDRAM controller issues the necessary precharges),
+	 * but is known to work on all supported boards
+	 */
+
+	PRECHARGE_BANK(0);
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS >= 2)
+	PRECHARGE_BANK(1);
+#endif
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS >= 3)
+	PRECHARGE_BANK(2);
+#endif
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS == 4)
+	PRECHARGE_BANK(3);
+#endif
+}
+
+static void setup_refresh_timer(void)
+{
+	struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE;
+
+	/* Load refresh timer with 10 to issue refresh every 10 cycles */
+	writel(0x0a, &sdram->refrshtimr);
+
+	/*
+	 * Wait at least 80 clock cycles to provide 8 refresh cycles
+	 * to all SDRAMs
+	 */
+	early_udelay(1);
+
+	/*
+	 * Program refresh timer with normal value
+	 * We need 8192 refresh cycles every 64ms
+	 * at 15ns (HCLK >= 66MHz) per cycle:
+	 * 64ms / 8192 = 7.8125us
+	 * 7.8125us / 15ns = 520 (0x208)
+	 */
+	/*
+	 * TODO: redboot uses 0x1e0 for the slowest possible device
+	 * but i don't understand how this value is calculated
+	 */
+	writel(0x208, &sdram->refrshtimr);
+}
+
+static void program_mode_registers(void)
+{
+	struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE;
+
+	/* Select mode register update mode */
+	writel(GLCONFIG_MRS | GLCONFIG_CKE, &sdram->glconfig);
+
+	PROGRAM_MODE_REG(0);
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS >= 2)
+	PROGRAM_MODE_REG(1);
+#endif
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS >= 3)
+	PROGRAM_MODE_REG(2);
+#endif
+
+#if (CONFIG_EP93XX_SDRAM_NUM_BANKS == 4)
+	PROGRAM_MODE_REG(3);
+#endif
+}