ARM: tegra: add function to enable input clamping on tristate

The HW-defined procedure for booting Tegra requires that
CLAMP_INPUTS_WHEN_TRISTATED be enabled before programming the pinmux.
Add a function to the pinmux driver to allow boards to do this.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NTom Warren <twarren@nvidia.com>

arch/arm/cpu/tegra-common/pinmux-common.c

@@ -86,6 +86,22 @@
 #define IO_RESET_SHIFT	8
 #define RCV_SEL_SHIFT	9
 
+#if !defined(CONFIG_TEGRA20) && !defined(CONFIG_TEGRA30)
+/* This register/field only exists on Tegra114 and later */
+#define APB_MISC_PP_PINMUX_GLOBAL_0 0x40
+#define CLAMP_INPUTS_WHEN_TRISTATED 1
+
+void pinmux_set_tristate_input_clamping(void)
+{
+	u32 *reg = _R(APB_MISC_PP_PINMUX_GLOBAL_0);
+	u32 val;
+
+	val = readl(reg);
+	val |= CLAMP_INPUTS_WHEN_TRISTATED;
+	writel(val, reg);
+}
+#endif
+
 void pinmux_set_func(enum pmux_pingrp pin, enum pmux_func func)
 {
 	u32 *reg = MUX_REG(pin);

arch/arm/include/asm/arch-tegra/pinmux.h

@@ -80,6 +80,11 @@ struct pmux_pingrp_config {
 #endif
 };
 
+#if !defined(CONFIG_TEGRA20) && !defined(CONFIG_TEGRA30)
+/* Set the pinmux CLAMP_INPUTS_WHEN_TRISTATED bit */
+void pinmux_set_tristate_input_clamping(void);
+#endif
+
 /* Set the mux function for a pin group */
 void pinmux_set_func(enum pmux_pingrp pin, enum pmux_func func);