memory: tegra: Introduce Tegra20 EMC driver

Introduce driver for the External Memory Controller (EMC) found on Tegra20
chips, which controls the external DRAM on the board. The purpose of this
driver is to program memory timing for external memory on the EMC clock
rate change.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/memory/tegra/Kconfig

@@ -6,6 +6,16 @@ config TEGRA_MC
 	  This driver supports the Memory Controller (MC) hardware found on
 	  NVIDIA Tegra SoCs.
 
+config TEGRA20_EMC
+	bool "NVIDIA Tegra20 External Memory Controller driver"
+	default y
+	depends on ARCH_TEGRA_2x_SOC
+	help
+	  This driver is for the External Memory Controller (EMC) found on
+	  Tegra20 chips. The EMC controls the external DRAM on the board.
+	  This driver is required to change memory timings / clock rate for
+	  external memory.
+
 config TEGRA124_EMC
 	bool "NVIDIA Tegra124 External Memory Controller driver"
 	default y

drivers/memory/tegra/Makefile

@@ -10,5 +10,6 @@ tegra-mc-$(CONFIG_ARCH_TEGRA_210_SOC) += tegra210.o
 
 obj-$(CONFIG_TEGRA_MC) += tegra-mc.o
 
+obj-$(CONFIG_TEGRA20_EMC)  += tegra20-emc.o
 obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
 obj-$(CONFIG_ARCH_TEGRA_186_SOC) += tegra186.o