PCI: armada8k: Add support for gpio controlled reset signal

Add support for the gpio reset signal binding as described in the
designware-pcie.txt DT binding document. Both the documented
'reset-gpio' property name and the more standard 'reset-gpios' name are
supported.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
index 0c389a30ef5d371135ff80adba6396a08f5a69c8..b171b6bc15c84c9fbef3ee20d992c2f526beeef3 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-armada8k.c
+++ b/drivers/pci/controller/dwc/pcie-armada8k.c
@@ -22,6 +22,7 @@
 #include <linux/resource.h>
 #include <linux/of_pci.h>
 #include <linux/of_irq.h>
+#include <linux/gpio/consumer.h>
 
 #include "pcie-designware.h"
 
@@ -29,6 +30,7 @@ struct armada8k_pcie {
        struct dw_pcie *pci;
        struct clk *clk;
        struct clk *clk_reg;
+       struct gpio_desc *reset_gpio;
 };
 
 #define PCIE_VENDOR_REGS_OFFSET                0x8000
@@ -137,6 +139,12 @@ static int armada8k_pcie_host_init(struct pcie_port *pp)
        struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
        struct armada8k_pcie *pcie = to_armada8k_pcie(pci);
 
+       if (pcie->reset_gpio) {
+               /* assert and then deassert the reset signal */
+               gpiod_set_value_cansleep(pcie->reset_gpio, 1);
+               msleep(100);
+               gpiod_set_value_cansleep(pcie->reset_gpio, 0);
+       }
        dw_pcie_setup_rc(pp);
        armada8k_pcie_establish_link(pcie);
 
@@ -249,6 +257,14 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
                goto fail_clkreg;
        }
 
+       /* Get reset gpio signal and hold asserted (logically high) */
+       pcie->reset_gpio = devm_gpiod_get_optional(dev, "reset",
+                                                  GPIOD_OUT_HIGH);
+       if (IS_ERR(pcie->reset_gpio)) {
+               ret = PTR_ERR(pcie->reset_gpio);
+               goto fail_clkreg;
+       }
+
        platform_set_drvdata(pdev, pcie);
 
        ret = armada8k_add_pcie_port(pcie, pdev);