pci: mx6: Implement power callback

Implement a callback to toggle the slot power supply. The callback
can be overriden in case some more complex power supply for the slot
was implemented in hardware, yet for the usual case, one can define
a GPIO which toggles the power to the slot.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Liu Ying <Ying.Liu@freescale.com>

drivers/pci/pcie_imx.c

@@ -451,6 +451,17 @@ static int imx6_pcie_init_phy(void)
 	return 0;
 }
 
+__weak int imx6_pcie_toggle_power(void)
+{
+#ifdef CONFIG_PCIE_IMX_POWER_GPIO
+	gpio_direction_output(CONFIG_PCIE_IMX_POWER_GPIO, 0);
+	mdelay(20);
+	gpio_set_value(CONFIG_PCIE_IMX_POWER_GPIO, 1);
+	mdelay(20);
+#endif
+	return 0;
+}
+
 __weak int imx6_pcie_toggle_reset(void)
 {
 	/*
@@ -496,7 +507,7 @@ static int imx6_pcie_deassert_core_reset(void)
 {
 	struct iomuxc *iomuxc_regs = (struct iomuxc *)IOMUXC_BASE_ADDR;
 
-	/* FIXME: Power-up GPIO goes here. */
+	imx6_pcie_toggle_power();
 
 	/* Enable PCIe */
 	clrbits_le32(&iomuxc_regs->gpr[1], IOMUXC_GPR1_TEST_POWERDOWN);