From dbdcc22c845be72d0b930a82ca20df8c92c677b9 Mon Sep 17 00:00:00 2001 From: Manikanta Maddireddy Date: Tue, 18 Jun 2019 23:32:05 +0530 Subject: 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: Manikanta Maddireddy [lorenzo.pieralisi@arm.com: squashed in fix in Link] Signed-off-by: Lorenzo Pieralisi Acked-by: Thierry Reding --- drivers/pci/controller/pci-tegra.c | 49 +++++++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 6 deletions(-) (limited to 'drivers/pci/controller/pci-tegra.c') diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c index 0fd1c1a8c1b9..6086c741cef7 100644 --- a/drivers/pci/controller/pci-tegra.c +++ b/drivers/pci/controller/pci-tegra.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -399,6 +400,8 @@ struct tegra_pcie_port { unsigned int lanes; struct phy **phys; + + struct gpio_desc *reset_gpio; }; struct tegra_pcie_bus { @@ -544,15 +547,23 @@ 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 (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); - value = afi_readl(port->pcie, ctrl); - value |= AFI_PEX_CTRL_RST; - afi_writel(port->pcie, value, ctrl); + 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); } -- cgit v1.2.3