[PATCH v2 3/4] PCI: imx6: Add power-supply support

[Sean Cross <xobs@kosagi.com>]

Some PCIe ports gate power to the slot.  In order to prevent system lockup,
these boards must enable power to the slot before attempting communication
over the PCI bus.

Signed-off-by: Sean Cross <xobs@kosagi.com>
---
 .../devicetree/bindings/pci/fsl,imx6q-pcie.txt     |  3 +++
 drivers/pci/host/pci-imx6.c                        | 27 ++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
index 6fbba53..a806b68 100644
--- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
@@ -13,6 +13,9 @@ Required properties:
 - clock-names: Must include the following additional entries:
 	- "pcie_phy"
 
+Optional properties:
+- bus-supply: A regulator that controls power to the entire bus
+
 Example:
 
 	pcie@0x01000000 {
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 69202d1..8e4f957 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -22,6 +22,7 @@
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 #include <linux/resource.h>
 #include <linux/signal.h>
 #include <linux/types.h>
@@ -39,6 +40,7 @@ struct imx6_pcie {
 	struct pcie_port	pp;
 	struct regmap		*iomuxc_gpr;
 	void __iomem		*mem_base;
+	struct regulator	*bus_supply;
 };
 
 /* PCIe Root Complex registers (memory-mapped) */
@@ -523,6 +525,7 @@ static struct pcie_host_ops imx6_pcie_host_ops = {
 static int __init imx6_add_pcie_port(struct pcie_port *pp,
 			struct platform_device *pdev)
 {
+	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
 	int ret;
 
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
@@ -544,9 +547,22 @@ static int __init imx6_add_pcie_port(struct pcie_port *pp,
 	pp->root_bus_nr = -1;
 	pp->ops = &imx6_pcie_host_ops;
 
+	if (imx6_pcie->bus_supply) {
+		ret = regulator_enable(imx6_pcie->bus_supply);
+		if (ret) {
+			dev_err(pp->dev,
+				"unable to enable bus supply: %d\n", ret);
+			return ret;
+		}
+	}
+
 	ret = dw_pcie_host_init(pp);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to initialize host\n");
+
+		if (imx6_pcie->bus_supply)
+			regulator_disable(imx6_pcie->bus_supply);
+
 		return ret;
 	}
 
@@ -588,6 +604,17 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
 		}
 	}
 
+	/* Fetch bus supply */
+	imx6_pcie->bus_supply = devm_regulator_get_optional(&pdev->dev, "bus");
+	if (IS_ERR(imx6_pcie->bus_supply)) {
+		ret = PTR_ERR(imx6_pcie->bus_supply);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		dev_err(&pdev->dev, "unable to get bus-supply\n");
+		return ret;
+	}
+
 	/* Fetch clocks */
 	imx6_pcie->pcie_phy = devm_clk_get(&pdev->dev, "pcie_phy");
 	if (IS_ERR(imx6_pcie->pcie_phy)) {
-- 
2.1.3