[PATCH v4 4/4] ARM: novena: Use DDR3 information from SPD EEPROM

[John Watts]

The Novena supports swappable memory which means we must query the memory
for configuration details. This patch uses values stored in the SPD EEPROM
to configure the i.MX6 memory controller.

If the SPD can't be read, the default configuration for a 4GB stick is
used. This is the same type of stick that comes with the board.

Calibration for the installed stick is run unconditionally.

Verification that this works was done by comparing MMDC registers before and
after and carefully reading other people's source code.

Signed-off-by: John Watts <contact at jookia.org>
---
 arch/arm/boards/novena/lowlevel.c | 94 +++++++++++++++++++++++++++++++
 arch/arm/mach-imx/Kconfig         |  2 +
 2 files changed, 96 insertions(+)

diff --git a/arch/arm/boards/novena/lowlevel.c b/arch/arm/boards/novena/lowlevel.c
index c49c6aab41..178c874892 100644
--- a/arch/arm/boards/novena/lowlevel.c
+++ b/arch/arm/boards/novena/lowlevel.c
@@ -3,6 +3,8 @@
 
 #include <asm/barebox-arm.h>
 #include <common.h>
+#include <ddr_dimms.h>
+#include <ddr_spd.h>
 #include <debug_ll.h>
 #include <mach/esdctl.h>
 #include <mach/generic.h>
@@ -10,6 +12,7 @@
 #include <mach/imx6-mmdc.h>
 #include <mach/iomux-mx6.h>
 #include <mach/xload.h>
+#include <pbl/i2c.h>
 #include <soc/fsl/fsl_udc.h>
 #include "ddr_regs.h"
 
@@ -17,6 +20,92 @@
 
 extern char __dtb_z_imx6q_novena_start[];
 
+static struct spd_eeprom spd_eeprom;
+static struct dimm_params dimm_params;
+
+static struct pbl_i2c *setup_spd_i2c(void)
+{
+	void __iomem *iomuxbase = IOMEM(MX6_IOMUXC_BASE_ADDR);
+	void __iomem *i2c1base = IOMEM(MX6_I2C1_BASE_ADDR);
+
+	imx_setup_pad(iomuxbase, MX6Q_PAD_CSI0_DAT8__I2C1_SDA);
+	imx_setup_pad(iomuxbase, MX6Q_PAD_CSI0_DAT9__I2C1_SCL);
+
+	return imx6_i2c_early_init(i2c1base);
+}
+
+static struct spd_eeprom *read_spd(void)
+{
+	struct spd_eeprom *eeprom = &spd_eeprom;
+	struct pbl_i2c *i2c = setup_spd_i2c();
+	int rc;
+
+	rc = spd_read_eeprom(i2c, 0x50, eeprom, SPD_MEMTYPE_DDR3);
+	if (rc < 0) {
+		pr_err("Couldn't read SPD EEPROM: %i\n", rc);
+		return NULL;
+	}
+
+	rc = ddr3_spd_check(&eeprom->ddr3);
+	if (rc < 0) {
+		pr_err("Couldn't verify SPD data: %i\n", rc);
+		return NULL;
+	}
+
+	return eeprom;
+}
+
+static void setup_dimm_settings(struct dimm_params *params,
+				struct mx6_ddr_sysinfo *info,
+				struct mx6_ddr3_cfg *cfg)
+{
+	int capacity_gbit = params->capacity / 0x8000000;
+	int density_rank = capacity_gbit / params->n_ranks;
+
+	info->ncs = params->n_ranks;
+	info->cs_density = density_rank;
+	cfg->mem_speed = params->tckmin_x_ps;
+	cfg->density = density_rank / params->n_banks_per_sdram_device;
+	cfg->width = params->data_width;
+	cfg->banks = params->n_banks_per_sdram_device;
+	cfg->rowaddr = params->n_row_addr;
+	cfg->coladdr = params->n_col_addr;
+	cfg->trcd = params->trcd_ps / 10;
+	cfg->trcmin = params->trc_ps / 10;
+	cfg->trasmin = params->tras_ps / 10;
+	cfg->SRT = params->extended_op_srt;
+
+	if (params->device_width >= 16)
+		cfg->pagesz = 2;
+}
+
+static void read_dimm_settings(void)
+{
+	struct spd_eeprom *eeprom = read_spd();
+	struct dimm_params *params = &dimm_params;
+	int rc;
+
+	if (!eeprom) {
+		pr_err("Couldn't read SPD EEPROM, using default settings\n");
+		return;
+	}
+
+	rc = ddr3_compute_dimm_parameters(&eeprom->ddr3, params);
+	if (rc < 0) {
+		pr_err("Couldn't compute DIMM params: %i\n", rc);
+		return;
+	}
+
+	pr_info("Found DIMM: %s\n", params->mpart);
+
+	if (params->primary_sdram_width != 64) {
+		pr_err("ERROR: DIMM stick memory width is not 64 bits\n");
+		hang();
+	}
+
+	setup_dimm_settings(params, &novena_ddr_info, &novena_ddr_cfg);
+}
+
 static bool running_from_ram(void)
 {
 	return (get_pc() >= MX6_MMDC_PORT01_BASE_ADDR);
@@ -39,8 +128,13 @@ static void setup_uart(void)
 
 static void setup_ram(void)
 {
+	read_dimm_settings();
+
 	mx6dq_dram_iocfg(64, &novena_ddr_regs, &novena_grp_regs);
 	mx6_dram_cfg(&novena_ddr_info, &novena_mmdc_calib, &novena_ddr_cfg);
+
+	mmdc_do_write_level_calibration();
+	mmdc_do_dqs_calibration();
 }
 
 static void load_barebox(void)
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index 912eef8290..dce5d9e1bb 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -438,6 +438,8 @@ config MACH_NOVENA
 	bool "Kosagi Novena board"
 	select ARCH_IMX6
 	select ARM_USE_COMPRESSED_DTB
+	select DDR_SPD
+	select I2C_IMX_EARLY
 	select MCI_IMX_ESDHC_PBL
 	select USB_GADGET_DRIVER_ARC_PBL
 
-- 
2.39.1