PCI: mvebu: add support for reset on GPIO

This patch adds a check for DT passed reset-gpios property and deasserts/
asserts reset pin on probe/remove with configurable delay. Corresponding
binding documentation is also updated.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

2 files changed, 38 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/pci/mvebu-pci.txt b/Documentation/devicetree/bindings/pci/mvebu-pci.txt
index 638673aec306..8bb3245e1946 100644
--- a/Documentation/devicetree/bindings/pci/mvebu-pci.txt
+++ b/Documentation/devicetree/bindings/pci/mvebu-pci.txt
@@ -76,6 +76,8 @@ and the following optional properties:
 - marvell,pcie-lane: the physical PCIe lane number, for ports having
   multiple lanes. If this property is not found, we assume that the
   value is 0.
+- reset-gpios: optional gpio to PERST#
+- reset-delay-us: delay in us to wait after reset de-assertion
 
 Example:
 
@@ -138,6 +140,10 @@ pcie-controller {
                 interrupt-map = <0 0 0 0 &mpic 58>;
                 marvell,pcie-port = <0>;
                 marvell,pcie-lane = <0>;
+                /* low-active PERST# reset on GPIO 25 */
+                reset-gpios = <&gpio0 25 1>;
+                /* wait 20ms for device settle after reset deassertion */
+                reset-delay-us = <20000>;
                 clocks = <&gateclk 5>;
                 status = "disabled";
         };
diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
index af23038a52ac..2d5f414bc45a 100644
--- a/drivers/pci/host/pci-mvebu.c
+++ b/drivers/pci/host/pci-mvebu.c
@@ -9,14 +9,17 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
 #include <linux/module.h>
 #include <linux/mbus.h>
 #include <linux/msi.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
-#include <linux/of_pci.h>
 #include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/of_pci.h>
 #include <linux/of_platform.h>
 
 /*
@@ -126,6 +129,9 @@ struct mvebu_pcie_port {
         unsigned int io_target;
         unsigned int io_attr;
         struct clk *clk;
+        int reset_gpio;
+        int reset_active_low;
+        char *reset_name;
         struct mvebu_sw_pci_bridge bridge;
         struct device_node *dn;
         struct mvebu_pcie *pcie;
@@ -857,6 +863,7 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
         i = 0;
         for_each_child_of_node(pdev->dev.of_node, child) {
                 struct mvebu_pcie_port *port = &pcie->ports[i];
+                enum of_gpio_flags flags;
 
                 if (!of_device_is_available(child))
                         continue;
@@ -897,6 +904,30 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
                         continue;
                 }
 
+                port->reset_gpio = of_get_named_gpio_flags(child,
+                                                   "reset-gpios", 0, &flags);
+                if (gpio_is_valid(port->reset_gpio)) {
+                        u32 reset_udelay = 20000;
+
+                        port->reset_active_low = flags & OF_GPIO_ACTIVE_LOW;
+                        port->reset_name = kasprintf(GFP_KERNEL,
+                                     "pcie%d.%d-reset", port->port, port->lane);
+                        of_property_read_u32(child, "reset-delay-us",
+                                             &reset_udelay);
+
+                        ret = devm_gpio_request_one(&pdev->dev,
+                            port->reset_gpio, GPIOF_DIR_OUT, port->reset_name);
+                        if (ret) {
+                                if (ret == -EPROBE_DEFER)
+                                        return ret;
+                                continue;
+                        }
+
+                        gpio_set_value(port->reset_gpio,
+                                       (port->reset_active_low) ? 1 : 0);
+                        msleep(reset_udelay/1000);
+                }
+
                 port->clk = of_clk_get_by_name(child, NULL);
                 if (IS_ERR(port->clk)) {
                         dev_err(&pdev->dev, "PCIe%d.%d: cannot get clock\n",