[PATCH 29/30] PCI: tegra: Add support for GPIO based PCIe reset

[Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>]

Add support for GPIO based PERST# instead of SFIO mode controller by AFI.
GPIO number comes from per port PCIe device tree node.

Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
---
 drivers/pci/controller/pci-tegra.c | 37 +++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
index 4a91c9fb3a9d..75873e6627f9 100644
--- a/drivers/pci/controller/pci-tegra.c
+++ b/drivers/pci/controller/pci-tegra.c
@@ -17,6 +17,7 @@
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/export.h>
+#include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/irq.h>
@@ -26,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/of_address.h>
+#include <linux/of_gpio.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/pci.h>
@@ -406,6 +408,7 @@ struct tegra_pcie_port {
 
 	int n_gpios;
 	int *gpios;
+	int rst_gpio;
 };
 
 struct tegra_pcie_bus {
@@ -589,15 +592,23 @@ static void tegra_pcie_port_reset(struct tegra_pcie_port *port)
 	unsigned long value;
 
 	/* pulse reset signal */
-	value = afi_readl(port->pcie, ctrl);
-	value &= ~AFI_PEX_CTRL_RST;
-	afi_writel(port->pcie, value, ctrl);
+	if (gpio_is_valid(port->rst_gpio)) {
+		gpio_set_value(port->rst_gpio, 0);
+	} else {
+		value = afi_readl(port->pcie, ctrl);
+		value &= ~AFI_PEX_CTRL_RST;
+		afi_writel(port->pcie, value, ctrl);
+	}
 
 	usleep_range(1000, 2000);
 
-	value = afi_readl(port->pcie, ctrl);
-	value |= AFI_PEX_CTRL_RST;
-	afi_writel(port->pcie, value, ctrl);
+	if (gpio_is_valid(port->rst_gpio)) {
+		gpio_set_value(port->rst_gpio, 1);
+	} else {
+		value = afi_readl(port->pcie, ctrl);
+		value |= AFI_PEX_CTRL_RST;
+		afi_writel(port->pcie, value, ctrl);
+	}
 }
 
 static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
@@ -2241,6 +2252,20 @@ static int tegra_pcie_parse_plat_dt(struct tegra_pcie_port *port,
 		}
 	}
 
+	port->rst_gpio = of_get_named_gpio(np, "nvidia,rst-gpio", 0);
+	if (gpio_is_valid(port->rst_gpio)) {
+		err = devm_gpio_request(dev, port->rst_gpio, "pex_rst_gpio");
+		if (err < 0) {
+			dev_err(dev, "rst_gpio request failed: %d\n", err);
+			return err;
+		}
+		err = gpio_direction_output(port->rst_gpio, 0);
+		if (err < 0) {
+			dev_err(dev, "rst_gpio set o/p failed: %d\n", err);
+			return err;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.17.1