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 <mmaddireddy@xxxxxxxxxx>
---
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 d3b9e6440dd6..2e55d64a0428 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>
@@ -400,6 +401,8 @@ struct tegra_pcie_port {
unsigned int lanes;
struct phy **phys;
+
+ struct gpio_desc *reset_gpio;
};
struct tegra_pcie_bus {
@@ -545,15 +548,23 @@ 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)
@@ -2200,6 +2211,7 @@ 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) {
@@ -2258,6 +2270,27 @@ 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
