[U-Boot] [PATCH 18/22] omap4: automatic sdram detection

[Aneesh V <aneesh@ti.com>]

Identify SDRAM devices connected to EMIF automatically:
LPDDR2 devices have some Mode Registers that provide details
about the device such as the type, density, bus width
etc. EMIF has the capability to read these registers. If there
are not devices connected to a given chip-select reading mode
registers will return junk values. After reading as many such
registers as possible and matching with expected ranges of
values the driver can identify if there is a device connected
to the respective CS. If we identify that a device is connected
the values read give us complete details about the device.

This along with the base AC timings specified by JESD209-2
allows us to do a complete automatic initialization of
SDRAM that works on all boards.

Please note that the default AC timings specified by JESD209-2
will be safe for all devices but not necessarily optimal. However,
for the Elpida devices used on Panda and SDP the default timings
are both safe and optimal.

Signed-off-by: Aneesh V <aneesh@ti.com>
---
 arch/arm/cpu/armv7/omap4/emif.c         |  177 +++++++++++++++++++++++++++++-
 arch/arm/cpu/armv7/omap4/sdram_elpida.c |    9 +-
 include/configs/omap4_sdp4430.h         |    1 +
 3 files changed, 176 insertions(+), 11 deletions(-)

diff --git a/arch/arm/cpu/armv7/omap4/emif.c b/arch/arm/cpu/armv7/omap4/emif.c
index 1bdb1d2..006d065 100644
--- a/arch/arm/cpu/armv7/omap4/emif.c
+++ b/arch/arm/cpu/armv7/omap4/emif.c
@@ -165,7 +165,8 @@ static const struct lpddr2_min_tck min_tck_jedec = {
 	.tFAW = 8
 };
 
-static const struct lpddr2_ac_timings *jedec_ac_timings[MAX_NUM_SPEEDBINS] = {
+static const struct lpddr2_ac_timings const*
+			jedec_ac_timings[MAX_NUM_SPEEDBINS] = {
 	&timings_jedec_200_mhz,
 	&timings_jedec_333_mhz,
 	&timings_jedec_400_mhz
@@ -779,6 +780,146 @@ void emif_reset_phy(u32 base)
 	writel(iodft, &emif->emif_iodft_tlgc);
 }
 
+#ifdef CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION
+static void display_sdram_details(u32 emif_nr, u32 cs,
+				  struct lpddr2_device_details *device)
+{
+	const char *mfg_str;
+	const char *type_str;
+	char density_str[10];
+	u32 density;
+
+	debug("EMIF%d CS%d\t", emif_nr, cs);
+
+	if (!device) {
+		debug("None\n");
+		return;
+	}
+
+	mfg_str = get_lpddr2_manufacturer(device->manufacturer);
+	type_str = get_lpddr2_type(device->type);
+
+	density = lpddr2_density_2_size_in_mbytes[device->density];
+	if ((density / 1024 * 1024) == density) {
+		density /= 1024;
+		sprintf(density_str, "%d GB", density);
+	} else
+		sprintf(density_str, "%d MB", density);
+	if (mfg_str && type_str)
+		debug("%s\t\t%s\t%s\n", mfg_str, type_str, density_str);
+}
+
+static u8 is_lpddr2_sdram_present(u32 base, u32 cs,
+				  struct lpddr2_device_details *lpddr2_device)
+{
+	u32 mr = 0, temp;
+
+	mr = get_mr(base, cs, LPDDR2_MR0);
+	if (mr > 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	temp = get_bit_field(mr, LPDDR2_MR0_DI_SHIFT, LPDDR2_MR0_DI_MASK);
+	if (temp) {
+		/* Not SDRAM */
+		return 0;
+	}
+	temp = get_bit_field(mr, LPDDR2_MR0_DNVI_SHIFT, LPDDR2_MR0_DNVI_MASK);
+
+	if (temp) {
+		/* DNV supported - But DNV is only supported for NVM */
+		return 0;
+	}
+
+	mr = get_mr(base, cs, LPDDR2_MR4);
+	if (mr > 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	mr = get_mr(base, cs, LPDDR2_MR5);
+	if (mr >= 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	if (!get_lpddr2_manufacturer(mr)) {
+		/* Manufacturer not identified */
+		return 0;
+	}
+	lpddr2_device->manufacturer = mr;
+
+	mr = get_mr(base, cs, LPDDR2_MR6);
+	if (mr >= 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	mr = get_mr(base, cs, LPDDR2_MR7);
+	if (mr >= 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	mr = get_mr(base, cs, LPDDR2_MR8);
+	if (mr >= 0xFF) {
+		/* Mode register value bigger than 8 bit */
+		return 0;
+	}
+
+	temp = get_bit_field(mr, MR8_TYPE_SHIFT, MR8_TYPE_MASK);
+	if (!get_lpddr2_type(temp)) {
+		/* Not SDRAM */
+		return 0;
+	}
+	lpddr2_device->type = temp;
+
+	temp = get_bit_field(mr, MR8_DENSITY_SHIFT, MR8_DENSITY_MASK);
+	if (temp > LPDDR2_DENSITY_32Gb) {
+		/* Density not supported */
+		return 0;
+	}
+	lpddr2_device->density = temp;
+
+	temp = get_bit_field(mr, MR8_IO_WIDTH_SHIFT, MR8_IO_WIDTH_MASK);
+	if (!get_lpddr2_io_width(temp)) {
+		/* IO width unsupported value */
+		return 0;
+	}
+	lpddr2_device->io_width = temp;
+
+	/*
+	 * If all the above tests pass we should
+	 * have a device on this chip-select
+	 */
+	return 1;
+}
+
+static struct lpddr2_device_details *get_lpddr2_details(u32 base, u8 cs,
+			struct lpddr2_device_details *lpddr2_dev_details)
+{
+	u32 phy;
+	struct emif_reg_struct *emif = (struct emif_reg_struct *)base;
+
+	if (!lpddr2_dev_details)
+		return NULL;
+
+	/* Do the minimum init for mode register accesses */
+	if (!running_from_sdram()) {
+		phy = get_ddr_phy_ctrl_1(get_syc_clk_freq() / 2, RL_BOOT);
+		writel(phy, &emif->emif_ddr_phy_ctrl_1);
+	}
+
+	if (!(is_lpddr2_sdram_present(base, cs, lpddr2_dev_details)))
+		return NULL;
+
+	display_sdram_details(emif_num(base), cs, lpddr2_dev_details);
+
+	return lpddr2_dev_details;
+}
+#endif /* CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION */
+
 static void do_lpddr2_init(u32 base, u32 cs)
 {
 	u32 mr_addr;
@@ -862,9 +1003,7 @@ static void emif_update_timings(u32 base, const struct emif_regs *regs)
 
 static void do_sdram_init(u32 base)
 {
-	struct emif_device_details dev_details;
 	const struct emif_regs *regs;
-
 	u32 in_sdram, emif_nr;
 
 	in_sdram = running_from_sdram();
@@ -872,6 +1011,7 @@ static void do_sdram_init(u32 base)
 
 #ifdef CONFIG_SYS_EMIF_PRECALCULATED_TIMING_REGS
 	const struct emif_regs *tmp_regs;
+
 	emif_get_reg_dump(&regs, &tmp_regs);
 	regs = (emif_nr == 1) ? regs : tmp_regs;
 #else
@@ -879,23 +1019,48 @@ static void do_sdram_init(u32 base)
 	 * The user has not provided the register values. We need to
 	 * calculate it based on the timings and the DDR frequency
 	 */
+	struct emif_device_details dev_details = { NULL, NULL };
+	struct emif_regs calculated_regs;
 
+#if !defined(CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION) || \
+	!defined(CONFIG_SYS_DEFAULT_LPDDR2_TIMINGS)
+
+	/* We need some input about the devices from the user */
 	const struct emif_device_details *dev_details_user_provided;
 	const struct emif_device_details *tmp_details;
-	struct emif_regs calculated_regs;
 
-	/* We need some input about the devices from the user */
 	emif_get_device_details(&dev_details_user_provided, &tmp_details);
 	dev_details_user_provided = (emif_nr == 1) ? dev_details_user_provided
 						   : tmp_details;
 	if (!dev_details_user_provided)
 		return;
+#endif
 
+#ifdef CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION
+	struct lpddr2_device_details cs0_dev_details, cs1_dev_details;
+
+	/* Automatically find the device details */
+	if (!in_sdram) {
+		dev_details.cs0_device_details =
+		    get_lpddr2_details(base, CS0, &cs0_dev_details);
+		dev_details.cs1_device_details =
+		    get_lpddr2_details(base, CS1, &cs1_dev_details);
+		/*
+		 * Reset the PHY - if there is nothing connected on any
+		 * of the chip selects(typically CS1) mode register reads
+		 * will mess up with the PHY state and subsequent
+		 * initialization won't work. PHY reset brings back PHY to
+		 * a good state.
+		 */
+		emif_reset_phy(base);
+	}
+#else
 	dev_details.cs0_device_details =
 			dev_details_user_provided->cs0_device_details;
 	dev_details.cs1_device_details =
 			dev_details_user_provided->cs1_device_details;
 
+#endif
 	/* Return if no devices on this EMIF */
 	if (!dev_details.cs0_device_details &&
 	    !dev_details.cs1_device_details) {
diff --git a/arch/arm/cpu/armv7/omap4/sdram_elpida.c b/arch/arm/cpu/armv7/omap4/sdram_elpida.c
index e7d2bd5..8dfe6f9 100644
--- a/arch/arm/cpu/armv7/omap4/sdram_elpida.c
+++ b/arch/arm/cpu/armv7/omap4/sdram_elpida.c
@@ -86,10 +86,8 @@ const struct dmm_lisa_map_regs lisa_map_2G_x_2_x_2 = {
 	.dmm_lisa_map_3 = 0x80640300
 };
 
-void emif_get_reg_dump_sdp(const struct emif_regs **emif1_regs,
-			const struct emif_regs **emif2_regs)
-
-#else
+#elif !defined(CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION) || \
+	!defined(CONFIG_SYS_DEFAULT_LPDDR2_TIMINGS)
 
 static const struct lpddr2_ac_timings timings_elpida_400_mhz = {
 	.max_freq	= 400000000,
@@ -245,7 +243,8 @@ static void emif_get_dmm_regs_sdp(const struct dmm_lisa_map_regs
 void emif_get_dmm_regs(const struct dmm_lisa_map_regs **dmm_lisa_regs)
 	__attribute__((weak, alias("emif_get_dmm_regs_sdp")));
 
-#else
+#elif !defined(CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION) || \
+	!defined(CONFIG_SYS_DEFAULT_LPDDR2_TIMINGS)
 
 static void emif_get_device_details_sdp(
 			const struct emif_device_details **emif1_details,
diff --git a/include/configs/omap4_sdp4430.h b/include/configs/omap4_sdp4430.h
index c29b184..a4332b7 100644
--- a/include/configs/omap4_sdp4430.h
+++ b/include/configs/omap4_sdp4430.h
@@ -247,6 +247,7 @@
 
 /* Defines for SDRAM init */
 #ifndef CONFIG_SYS_EMIF_PRECALCULATED_TIMING_REGS
+#define CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION	1
 #define CONFIG_SYS_DEFAULT_LPDDR2_TIMINGS	1
 #endif
 
-- 
1.7.0.4