tegra: i2c: Add function to find DVC bus

Add tegra_i2c_get_dvc_bus_num() to obtain the I2C bus number of DVC bus.
This allows us to talk to the PMU.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/include/asm/arch-tegra2/tegra_i2c.h

@@ -154,4 +154,11 @@ struct i2c_ctlr {
 #define I2C_INT_ARBITRATION_LOST_SHIFT	2
 #define I2C_INT_ARBITRATION_LOST_MASK	(1 << I2C_INT_ARBITRATION_LOST_SHIFT)
 
+/**
+ * Returns the bus number of the DVC controller
+ *
+ * @return number of bus, or -1 if there is no DVC active
+ */
+int tegra_i2c_get_dvc_bus_num(void);
+
 #endif

drivers/i2c/tegra_i2c.c

@@ -567,3 +567,17 @@ int i2c_set_bus_num(unsigned int bus)
 	return 0;
 }
 #endif
+
+int tegra_i2c_get_dvc_bus_num(void)
+{
+	int i;
+
+	for (i = 0; i < CONFIG_SYS_MAX_I2C_BUS; i++) {
+		struct i2c_bus *bus = &i2c_controllers[i];
+
+		if (bus->inited && bus->is_dvc)
+			return i;
+	}
+
+	return -1;
+}