tegra: Turn off power detect in board init

Tegra core power rail has leakage voltage around 0.2V while system in
suspend mode. The source of the leakage should be coming from PMC power
detect logic for IO rails power detection.
That can be disabled by writing a '0' to PWR_DET_LATCH followed by writing '0'
to PWR_DET (APBDEV_PMC_PWR_DET_0).

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

board/nvidia/common/board.c

@@ -61,6 +61,21 @@ void __pin_mux_usb(void)
 
 void pin_mux_usb(void) __attribute__((weak, alias("__pin_mux_usb")));
 
+/*
+ * Routine: power_det_init
+ * Description: turn off power detects
+ */
+static void power_det_init(void)
+{
+#if defined(CONFIG_TEGRA2)
+	struct pmc_ctlr *const pmc = (struct pmc_ctlr *)TEGRA2_PMC_BASE;
+
+	/* turn off power detects */
+	writel(0, &pmc->pmc_pwr_det_latch);
+	writel(0, &pmc->pmc_pwr_det);
+#endif
+}
+
 /*
  * Routine: board_init
  * Description: Early hardware init.
@@ -79,6 +94,9 @@ int board_init(void)
 #endif
 	/* boot param addr */
 	gd->bd->bi_boot_params = (NV_PA_SDRAM_BASE + 0x100);
+
+	power_det_init();
+
 #ifdef CONFIG_TEGRA_I2C
 #ifndef CONFIG_SYS_I2C_INIT_BOARD
 #error "You must define CONFIG_SYS_I2C_INIT_BOARD to use i2c on Nvidia boards"