On Fri, Apr 24, 2020 at 10:39 AM Pali Rohár <pali@xxxxxxxxxx> wrote:
>
> Add support for issuing PERST via GPIO specified in 'reset-gpios'
> property (as described in PCI device tree bindings).
>
> Some buggy cards (e.g. Compex WLE900VX or WLE1216) are not detected
> after reboot when PERST is not issued during driver initialization.
>
> If bootloader already enabled link training then issuing PERST has no
> effect for some buggy cards (e.g. Compex WLE900VX) and these cards are
> not detected. We therefore clear the LINK_TRAINING_EN register before.
>
> It was observed that Compex WLE900VX card needs to be in PERST reset
> for at least 10ms if bootloader enabled link training.
>
> Tested on Turris MOX.
>
> Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> ---
> drivers/pci/controller/pci-aardvark.c | 43 ++++++++++++++++++++++++++-
> 1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index a6c4d4d52631..9e2f44213b5e 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -9,6 +9,7 @@
> */
>
> #include <linux/delay.h>
> +#include <linux/gpio.h>
> #include <linux/interrupt.h>
> #include <linux/irq.h>
> #include <linux/irqdomain.h>
> @@ -18,6 +19,7 @@
> #include <linux/platform_device.h>
> #include <linux/msi.h>
> #include <linux/of_address.h>
> +#include <linux/of_gpio.h>
> #include <linux/of_pci.h>
>
> #include "../pci.h"
> @@ -204,6 +206,7 @@ struct advk_pcie {
> int root_bus_nr;
> int link_gen;
> struct pci_bridge_emul bridge;
> + struct gpio_desc *reset_gpio;
> };
>
> static inline void advk_writel(struct advk_pcie *pcie, u32 val, u64 reg)
> @@ -330,10 +333,31 @@ static void advk_pcie_train_link(struct advk_pcie *pcie)
> dev_err(dev, "link never came up\n");
> }
>
> +static void advk_pcie_issue_perst(struct advk_pcie *pcie)
> +{
> + u32 reg;
> +
> + if (!pcie->reset_gpio)
> + return;
> +
> + /* PERST does not work for some cards when link training is enabled */
> + reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
> + reg &= ~LINK_TRAINING_EN;
> + advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
> +
> + /* 10ms delay is needed for some cards */
> + dev_info(&pcie->pdev->dev, "issuing PERST via reset GPIO for 10ms\n");
> + gpiod_set_value_cansleep(pcie->reset_gpio, 1);
> + usleep_range(10000, 11000);
> + gpiod_set_value_cansleep(pcie->reset_gpio, 0);
> +}
> +
> static void advk_pcie_setup_hw(struct advk_pcie *pcie)
> {
> u32 reg;
>
> + advk_pcie_issue_perst(pcie);
> +
> /* Set to Direct mode */
> reg = advk_readl(pcie, CTRL_CONFIG_REG);
> reg &= ~(CTRL_MODE_MASK << CTRL_MODE_SHIFT);
> @@ -406,7 +430,8 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
>
> /*
> * PERST# signal could have been asserted by pinctrl subsystem before
> - * probe() callback has been called, making the endpoint going into
> + * probe() callback has been called or issued explicitly by reset gpio
> + * function advk_pcie_issue_perst(), making the endpoint going into
> * fundamental reset. As required by PCI Express spec a delay for at
> * least 100ms after such a reset before link training is needed.
> */
> @@ -1046,6 +1071,22 @@ static int advk_pcie_probe(struct platform_device *pdev)
> }
> pcie->root_bus_nr = bus->start;
>
> + pcie->reset_gpio = devm_gpiod_get_from_of_node(dev, dev->of_node,
> + "reset-gpios", 0,
> + GPIOD_OUT_LOW,
> + "pcie1-reset");
> + ret = PTR_ERR_OR_ZERO(pcie->reset_gpio);
> + if (ret) {
> + if (ret == -ENOENT) {
> + pcie->reset_gpio = NULL;
> + } else {
> + if (ret != -EPROBE_DEFER)
> + dev_err(dev, "Failed to get reset-gpio: %i\n",
> + ret);
> + return ret;
> + }
> + }
I believe all this can be replaced with devm_gpiod_get_optional.
Rob
