--- /dev/null
+From 5169a9851daaa2782a7bd2bb83d5b1bd224b2879 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali@kernel.org>
+Date: Thu, 30 Apr 2020 10:06:18 +0200
+Subject: [PATCH] PCI: aardvark: Issue PERST via GPIO
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+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.
+
+Link: https://lore.kernel.org/r/20200430080625.26070-6-pali@kernel.org
+Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
+Signed-off-by: Pali Rohár <pali@kernel.org>
+Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ drivers/pci/controller/pci-aardvark.c | 43 ++++++++++++++++++++++++++-
+ 1 file changed, 42 insertions(+), 1 deletion(-)
+
+--- 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>
+@@ -17,6 +18,7 @@
+ #include <linux/init.h>
+ #include <linux/platform_device.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 @@ err:
+ 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 ad
+
+ /*
+ * 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.
+ */
+@@ -1093,6 +1118,22 @@ static int advk_pcie_probe(struct platfo
+ return ret;
+ }
+
++ 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;
++ }
++ }
++
+ ret = of_pci_get_max_link_speed(dev->of_node);
+ if (ret <= 0 || ret > 3)
+ pcie->link_gen = 3;
projects / openwrt / openwrt.git / blobdiff