memory: tegra: Add EMC scaling support code for Tegra210

This is the initial patch for Tegra210 EMC frequency scaling. It has the
code to program various aspects of the EMC that are standardized, but it
does not yet include the specific programming sequence needed for clock
scaling.

The driver is designed to support LPDDR4 SDRAM. Devices that use LPDDR4
need to perform training of the RAM before it can be used. Firmware will
perform this training during early boot and pass a table of supported
frequencies to the kernel via device tree.

For the frequencies above 800 MHz, periodic retraining is needed to
compensate for changes in timing. This periodic training will have to be
performed until the frequency drops back to or below 800 MHz.

This driver provides helpers used during this runtime retraining that
will be used by the sequence specific code in a follow-up patch.

Based on work by Peter De Schrijver <[email protected]>.

Signed-off-by: Joseph Lo <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>

Author: joseph-lo-nvtw

drivers/memory/tegra/Kconfig

@@ -36,3 +36,17 @@ config TEGRA124_EMC
 	  Tegra124 chips. The EMC controls the external DRAM on the board.
 	  This driver is required to change memory timings / clock rate for
 	  external memory.
+
+config TEGRA210_EMC_TABLE
+	bool
+	depends on ARCH_TEGRA_210_SOC
+
+config TEGRA210_EMC
+	tristate "NVIDIA Tegra210 External Memory Controller driver"
+	depends on TEGRA_MC && ARCH_TEGRA_210_SOC
+	select TEGRA210_EMC_TABLE
+	help
+	  This driver is for the External Memory Controller (EMC) found on
+	  Tegra210 chips. The EMC controls the external DRAM on the board.
+	  This driver is required to change memory timings / clock rate for
+	  external memory.

drivers/memory/tegra/Makefile

@@ -13,5 +13,9 @@ obj-$(CONFIG_TEGRA_MC) += tegra-mc.o
 obj-$(CONFIG_TEGRA20_EMC)  += tegra20-emc.o
 obj-$(CONFIG_TEGRA30_EMC)  += tegra30-emc.o
 obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
+obj-$(CONFIG_TEGRA210_EMC_TABLE) += tegra210-emc-table.o
+obj-$(CONFIG_TEGRA210_EMC) += tegra210-emc.o
 obj-$(CONFIG_ARCH_TEGRA_186_SOC) += tegra186.o tegra186-emc.o
 obj-$(CONFIG_ARCH_TEGRA_194_SOC) += tegra186.o tegra186-emc.o
+
+tegra210-emc-y := tegra210-emc-core.o

drivers/memory/tegra/mc.h

@@ -34,6 +34,7 @@
 #define MC_EMEM_ARB_TIMING_W2W				0xbc
 #define MC_EMEM_ARB_TIMING_R2W				0xc0
 #define MC_EMEM_ARB_TIMING_W2R				0xc4
+#define MC_EMEM_ARB_MISC2				0xc8
 #define MC_EMEM_ARB_DA_TURNS				0xd0
 #define MC_EMEM_ARB_DA_COVERS				0xd4
 #define MC_EMEM_ARB_MISC0				0xd8