Commit dbdcc22c authored by Manikanta Maddireddy's avatar Manikanta Maddireddy Committed by Lorenzo Pieralisi
Browse files

PCI: tegra: Add support for GPIO based PERST# 

Tegra PCIe has fixed per port SFIO line to signal PERST#, which can be
controlled by AFI port register. However, if a platform routes a
different GPIO to the PCIe slot, then port register cannot control it.
Add support for GPIO based PERST# signal for such platforms. GPIO number
comes from per port PCIe device tree node. PCIe driver probe doesn't
fail if per port "reset-gpios" property is not populated, so platforms
that require this workaround must make sure that the DT property is not
missed in the corresponding device tree.

Link: https://lore.kernel.org/linux-pci/20190705084850.30777-1-jonathanh@nvidia.com/


Signed-off-by: default avatarManikanta Maddireddy <mmaddireddy@nvidia.com>
[lorenzo.pieralisi@arm.com: squashed in fix in Link]
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: default avatarThierry Reding <treding@nvidia.com>
parent 0fc8b82f

drivers/pci/controller/pci-tegra.c

+43 −6
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/debugfs.h>

#include <linux/delay.h>

#include <linux/export.h>

#include <linux/gpio/consumer.h>

#include <linux/interrupt.h>

#include <linux/iopoll.h>

#include <linux/irq.h>
@@ -399,6 +400,8 @@ struct tegra_pcie_port { 
	unsigned int lanes;



	struct phy **phys;



	struct gpio_desc *reset_gpio;

};



struct tegra_pcie_bus {
@@ -544,16 +547,24 @@ static void tegra_pcie_port_reset(struct tegra_pcie_port *port) 
	unsigned long value;



	/* pulse reset signal */

	if (port->reset_gpio) {

		gpiod_set_value(port->reset_gpio, 1);

	} else {

		value = afi_readl(port->pcie, ctrl);

		value &= ~AFI_PEX_CTRL_RST;

		afi_writel(port->pcie, value, ctrl);

	}



	usleep_range(1000, 2000);



	if (port->reset_gpio) {

		gpiod_set_value(port->reset_gpio, 0);

	} 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)

{
@@ -2218,6 +2229,7 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie) 
		struct tegra_pcie_port *rp;

		unsigned int index;

		u32 value;

		char *label;



		err = of_pci_get_devfn(port);

		if (err < 0) {
@@ -2276,6 +2288,31 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie) 
		if (IS_ERR(rp->base))

			return PTR_ERR(rp->base);



		label = devm_kasprintf(dev, GFP_KERNEL, "pex-reset-%u", index);

		if (!label) {

			dev_err(dev, "failed to create reset GPIO label\n");

			return -ENOMEM;

		}



		/*

		 * Returns -ENOENT if reset-gpios property is not populated

		 * and in this case fall back to using AFI per port register

		 * to toggle PERST# SFIO line.

		 */

		rp->reset_gpio = devm_gpiod_get_from_of_node(dev, port,

							     "reset-gpios", 0,

							     GPIOD_OUT_LOW,

							     label);

		if (IS_ERR(rp->reset_gpio)) {

			if (PTR_ERR(rp->reset_gpio) == -ENOENT) {

				rp->reset_gpio = NULL;

			} else {

				dev_err(dev, "failed to get reset GPIO: %d\n",

					err);

				return PTR_ERR(rp->reset_gpio);

			}

		}



		list_add_tail(&rp->list, &pcie->ports);

	}

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