tegra: Add EMC support for optimal memory timings

Add support for setting up the memory controller parameters. Boards
can set up an appropriate table in the device tree.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

2 files changed, 287 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/tegra2/Makefile b/arch/arm/cpu/armv7/tegra2/Makefile
index e9ac6c9a71..dcd6329405 100644
--- a/arch/arm/cpu/armv7/tegra2/Makefile
+++ b/arch/arm/cpu/armv7/tegra2/Makefile
@@ -34,6 +34,7 @@ LIB	=  $(obj)lib$(SOC).o
 
 SOBJS	:= lowlevel_init.o
 COBJS-y	:= ap20.o board.o clock.o funcmux.o pinmux.o sys_info.o timer.o
+COBJS-$(CONFIG_TEGRA_CLOCK_SCALING) += emc.o
 COBJS-$(CONFIG_USB_EHCI_TEGRA) += usb.o
 
 COBJS	:= $(COBJS-y)
diff --git a/arch/arm/cpu/armv7/tegra2/emc.c b/arch/arm/cpu/armv7/tegra2/emc.c
new file mode 100644
index 0000000000..c0e5c565f1
--- /dev/null
+++ b/arch/arm/cpu/armv7/tegra2/emc.c
@@ -0,0 +1,286 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ *
+ * 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 <fdtdec.h>
+#include <asm/io.h>
+#include <asm/arch/ap20.h>
+#include <asm/arch/apb_misc.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/emc.h>
+#include <asm/arch/tegra2.h>
+
+/*
+ * The EMC registers have shadow registers.  When the EMC clock is updated
+ * in the clock controller, the shadow registers are copied to the active
+ * registers, allowing glitchless memory bus frequency changes.
+ * This function updates the shadow registers for a new clock frequency,
+ * and relies on the clock lock on the emc clock to avoid races between
+ * multiple frequency changes
+ */
+
+/*
+ * This table defines the ordering of the registers provided to
+ * tegra_set_mmc()
+ * TODO: Convert to fdt version once available
+ */
+static const unsigned long emc_reg_addr[TEGRA_EMC_NUM_REGS] = {
+	0x2c,	/* RC */
+	0x30,	/* RFC */
+	0x34,	/* RAS */
+	0x38,	/* RP */
+	0x3c,	/* R2W */
+	0x40,	/* W2R */
+	0x44,	/* R2P */
+	0x48,	/* W2P */
+	0x4c,	/* RD_RCD */
+	0x50,	/* WR_RCD */
+	0x54,	/* RRD */
+	0x58,	/* REXT */
+	0x5c,	/* WDV */
+	0x60,	/* QUSE */
+	0x64,	/* QRST */
+	0x68,	/* QSAFE */
+	0x6c,	/* RDV */
+	0x70,	/* REFRESH */
+	0x74,	/* BURST_REFRESH_NUM */
+	0x78,	/* PDEX2WR */
+	0x7c,	/* PDEX2RD */
+	0x80,	/* PCHG2PDEN */
+	0x84,	/* ACT2PDEN */
+	0x88,	/* AR2PDEN */
+	0x8c,	/* RW2PDEN */
+	0x90,	/* TXSR */
+	0x94,	/* TCKE */
+	0x98,	/* TFAW */
+	0x9c,	/* TRPAB */
+	0xa0,	/* TCLKSTABLE */
+	0xa4,	/* TCLKSTOP */
+	0xa8,	/* TREFBW */
+	0xac,	/* QUSE_EXTRA */
+	0x114,	/* FBIO_CFG6 */
+	0xb0,	/* ODT_WRITE */
+	0xb4,	/* ODT_READ */
+	0x104,	/* FBIO_CFG5 */
+	0x2bc,	/* CFG_DIG_DLL */
+	0x2c0,	/* DLL_XFORM_DQS */
+	0x2c4,	/* DLL_XFORM_QUSE */
+	0x2e0,	/* ZCAL_REF_CNT */
+	0x2e4,	/* ZCAL_WAIT_CNT */
+	0x2a8,	/* AUTO_CAL_INTERVAL */
+	0x2d0,	/* CFG_CLKTRIM_0 */
+	0x2d4,	/* CFG_CLKTRIM_1 */
+	0x2d8,	/* CFG_CLKTRIM_2 */
+};
+
+struct emc_ctlr *emc_get_controller(const void *blob)
+{
+	fdt_addr_t addr;
+	int node;
+
+	node = fdtdec_next_compatible(blob, 0, COMPAT_NVIDIA_TEGRA20_EMC);
+	if (node > 0) {
+		addr = fdtdec_get_addr(blob, node, "reg");
+		if (addr != FDT_ADDR_T_NONE)
+			return (struct emc_ctlr *)addr;
+	}
+	return NULL;
+}
+
+/* Error codes we use */
+enum {
+	ERR_NO_EMC_NODE = -10,
+	ERR_NO_EMC_REG,
+	ERR_NO_FREQ,
+	ERR_FREQ_NOT_FOUND,
+	ERR_BAD_REGS,
+	ERR_NO_RAM_CODE,
+	ERR_RAM_CODE_NOT_FOUND,
+};
+
+/**
+ * Find EMC tables for the given ram code.
+ *
+ * The tegra EMC binding has two options, one using the ram code and one not.
+ * We detect which is in use by looking for the nvidia,use-ram-code property.
+ * If this is not present, then the EMC tables are directly below 'node',
+ * otherwise we select the correct emc-tables subnode based on the 'ram_code'
+ * value.
+ *
+ * @param blob		Device tree blob
+ * @param node		EMC node (nvidia,tegra20-emc compatible string)
+ * @param ram_code	RAM code to select (0-3, or -1 if unknown)
+ * @return 0 if ok, otherwise a -ve ERR_ code (see enum above)
+ */
+static int find_emc_tables(const void *blob, int node, int ram_code)
+{
+	int need_ram_code;
+	int depth;
+	int offset;
+
+	/* If we are using RAM codes, scan through the tables for our code */
+	need_ram_code = fdtdec_get_bool(blob, node, "nvidia,use-ram-code");
+	if (!need_ram_code)
+		return node;
+	if (ram_code == -1) {
+		debug("%s: RAM code required but not supplied\n", __func__);
+		return ERR_NO_RAM_CODE;
+	}
+
+	offset = node;
+	depth = 0;
+	do {
+		/*
+		 * Sadly there is no compatible string so we cannot use
+		 * fdtdec_next_compatible_subnode().
+		 */
+		offset = fdt_next_node(blob, offset, &depth);
+		if (depth <= 0)
+			break;
+
+		/* Make sure this is a direct subnode */
+		if (depth != 1)
+			continue;
+		if (strcmp("emc-tables", fdt_get_name(blob, offset, NULL)))
+			continue;
+
+		if (fdtdec_get_int(blob, offset, "nvidia,ram-code", -1)
+				== ram_code)
+			return offset;
+	} while (1);
+
+	debug("%s: Could not find tables for RAM code %d\n", __func__,
+	      ram_code);
+	return ERR_RAM_CODE_NOT_FOUND;
+}
+
+/**
+ * Decode the EMC node of the device tree, returning a pointer to the emc
+ * controller and the table to be used for the given rate.
+ *
+ * @param blob	Device tree blob
+ * @param rate	Clock speed of memory controller in Hz (=2x memory bus rate)
+ * @param emcp	Returns address of EMC controller registers
+ * @param tablep Returns pointer to table to program into EMC. There are
+ *		TEGRA_EMC_NUM_REGS entries, destined for offsets as per the
+ *		emc_reg_addr array.
+ * @return 0 if ok, otherwise a -ve error code which will allow someone to
+ * figure out roughly what went wrong by looking at this code.
+ */
+static int decode_emc(const void *blob, unsigned rate, struct emc_ctlr **emcp,
+		      const u32 **tablep)
+{
+	struct apb_misc_pp_ctlr *pp =
+		(struct apb_misc_pp_ctlr *)NV_PA_APB_MISC_BASE;
+	int ram_code;
+	int depth;
+	int node;
+
+	ram_code = (readl(&pp->strapping_opt_a) & RAM_CODE_MASK)
+			>> RAM_CODE_SHIFT;
+	/*
+	 * The EMC clock rate is twice the bus rate, and the bus rate is
+	 * measured in kHz
+	 */
+	rate = rate / 2 / 1000;
+
+	node = fdtdec_next_compatible(blob, 0, COMPAT_NVIDIA_TEGRA20_EMC);
+	if (node < 0) {
+		debug("%s: No EMC node found in FDT\n", __func__);
+		return ERR_NO_EMC_NODE;
+	}
+	*emcp = (struct emc_ctlr *)fdtdec_get_addr(blob, node, "reg");
+	if (*emcp == (struct emc_ctlr *)FDT_ADDR_T_NONE) {
+		debug("%s: No EMC node reg property\n", __func__);
+		return ERR_NO_EMC_REG;
+	}
+
+	/* Work out the parent node which contains our EMC tables */
+	node = find_emc_tables(blob, node, ram_code & 3);
+	if (node < 0)
+		return node;
+
+	depth = 0;
+	for (;;) {
+		int node_rate;
+
+		node = fdtdec_next_compatible_subnode(blob, node,
+				COMPAT_NVIDIA_TEGRA20_EMC_TABLE, &depth);
+		if (node < 0)
+			break;
+		node_rate = fdtdec_get_int(blob, node, "clock-frequency", -1);
+		if (node_rate == -1) {
+			debug("%s: Missing clock-frequency\n", __func__);
+			return ERR_NO_FREQ; /* we expect this property */
+		}
+
+		if (node_rate == rate)
+			break;
+	}
+	if (node < 0) {
+		debug("%s: No node found for clock frequency %d\n", __func__,
+		      rate);
+		return ERR_FREQ_NOT_FOUND;
+	}
+
+	*tablep = fdtdec_locate_array(blob, node, "nvidia,emc-registers",
+				      TEGRA_EMC_NUM_REGS);
+	if (!*tablep) {
+		debug("%s: node '%s' array missing / wrong size\n", __func__,
+		      fdt_get_name(blob, node, NULL));
+		return ERR_BAD_REGS;
+	}
+
+	/* All seems well */
+	return 0;
+}
+
+int tegra_set_emc(const void *blob, unsigned rate)
+{
+	struct emc_ctlr *emc;
+	const u32 *table;
+	int err, i;
+
+	err = decode_emc(blob, rate, &emc, &table);
+	if (err) {
+		debug("Warning: no valid EMC (%d), memory timings unset\n",
+		       err);
+		return err;
+	}
+
+	debug("%s: Table found, setting EMC values as follows:\n", __func__);
+	for (i = 0; i < TEGRA_EMC_NUM_REGS; i++) {
+		u32 value = fdt32_to_cpu(table[i]);
+		u32 addr = (uintptr_t)emc + emc_reg_addr[i];
+
+		debug("   %#x: %#x\n", addr, value);
+		writel(value, addr);
+	}
+
+	/* trigger emc with new settings */
+	clock_adjust_periph_pll_div(PERIPH_ID_EMC, CLOCK_ID_MEMORY,
+				clock_get_rate(CLOCK_ID_MEMORY), NULL);
+	debug("EMC clock set to %lu\n",
+	      clock_get_periph_rate(PERIPH_ID_EMC, CLOCK_ID_MEMORY));
+
+	return 0;
+}