In platforms like TI's J721E EVM, the PERST# line is connected to a GPIO line and PERST# should be driven high to indicate the clocks are stable (As per Figure 2-10: Power Up of the PCIe CEM spec 3.0).
Add support to make GPIO drive PERST# line. Signed-off-by: Kishon Vijay Abraham I <[email protected]> --- drivers/pci/controller/pcie-cadence-host.c | 26 ++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/drivers/pci/controller/pcie-cadence-host.c b/drivers/pci/controller/pcie-cadence-host.c index 4ad8f2ece6e2..8b3b9827a8d6 100644 --- a/drivers/pci/controller/pcie-cadence-host.c +++ b/drivers/pci/controller/pcie-cadence-host.c @@ -3,6 +3,8 @@ // Cadence PCIe host controller driver. // Author: Cyrille Pitchen <[email protected]> +#include <linux/delay.h> +#include <linux/gpio/consumer.h> #include <linux/kernel.h> #include <linux/of_address.h> #include <linux/of_device.h> @@ -287,6 +289,7 @@ static int cdns_pcie_host_probe(struct platform_device *pdev) struct pci_host_bridge *bridge; struct list_head resources; struct cdns_pcie_rc *rc; + struct gpio_desc *gpiod; struct cdns_pcie *pcie; struct resource *res; int ret; @@ -349,13 +352,36 @@ static int cdns_pcie_host_probe(struct platform_device *pdev) dev_err(dev, "missing \"mem\"\n"); return -EINVAL; } + pcie->mem_res = res; + gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); + if (IS_ERR(gpiod)) { + ret = PTR_ERR(gpiod); + if (ret != -EPROBE_DEFER) + dev_err(dev, "Failed to get reset GPIO\n"); + return ret; + } + ret = cdns_pcie_init_phy(dev, pcie); if (ret) { dev_err(dev, "failed to init phy\n"); return ret; } + + /* + * "Power Sequencing and Reset Signal Timings" table in + * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 3.0 + * indicates PERST# should be deasserted after minimum of 100us + * once REFCLK is stable. The REFCLK to the connector in RC + * mode is selected while enabling the PHY. So deassert PERST# + * after 100 us. + */ + if (gpiod) { + usleep_range(100, 200); + gpiod_set_value_cansleep(gpiod, 1); + } + platform_set_drvdata(pdev, pcie); pm_runtime_enable(dev); -- 2.17.1
