From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Manikanta Maddireddy Subject: [PATCH V6 26/27] PCI: tegra: Add support for GPIO based PERST# Date: Tue, 18 Jun 2019 23:32:05 +0530 Message-ID: <20190618180206.4908-27-mmaddireddy@nvidia.com> In-Reply-To: <20190618180206.4908-1-mmaddireddy@nvidia.com> References: <20190618180206.4908-1-mmaddireddy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain To: thierry.reding@gmail.com, bhelgaas@google.com, robh+dt@kernel.org, mark.rutland@arm.com, jonathanh@nvidia.com, lorenzo.pieralisi@arm.com, vidyas@nvidia.com Cc: linux-tegra@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, Manikanta Maddireddy List-ID: 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, make sure that DT property is not missed for such platforms. Signed-off-by: Manikanta Maddireddy Acked-by: Thierry Reding --- V6: No change V5: * Updated reset gpio toggle logic to reflect active low usage * Replaced kasprintf() with devm_kasprintf() * Updated commit message with more information. V4: Using devm_gpiod_get_from_of_node() to get reset-gpios V3: Using helper function to get reset-gpios V2: Using standard "reset-gpio" property drivers/pci/controller/pci-tegra.c | 45 ++++++++++++++++++++++++++---- 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c index d2841532ff0e..a819bc087a05 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) @@ -2199,6 +2210,7 @@ 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) { @@ -2257,6 +2269,27 @@ 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 null if reset-gpios property is not populated and + * 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)) { + err = PTR_ERR(rp->reset_gpio); + dev_err(dev, "failed to get reset GPIO: %d\n", err); + return err; + } + list_add_tail(&rp->list, &pcie->ports); } -- 2.17.1