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Subject[PATCH] PCI: dwc: artpec6: Add reset-gpios for PERST# control
Some devices need an optional external gpio for controlling
the PERST# signal to bring up for example a PCIe switch
after a soft reset.

Without this, some boards (the ARTPEC-6 master devboard)
would not get the PCIe link back after a soft reset.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
---
.../devicetree/bindings/pci/axis,artpec6-pcie.txt | 4 ++++
drivers/pci/dwc/pcie-artpec6.c | 20 +++++++++++++++++++-
2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/pci/axis,artpec6-pcie.txt b/Documentation/devicetree/bindings/pci/axis,artpec6-pcie.txt
index 979dc7b6cfe8..810bd461e81c 100644
--- a/Documentation/devicetree/bindings/pci/axis,artpec6-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/axis,artpec6-pcie.txt
@@ -21,6 +21,10 @@ and thus inherits all the common properties defined in designware-pcie.txt.
- axis,syscon-pcie: A phandle pointing to the ARTPEC-6 system controller,
used to enable and control the Synopsys IP.

+Optional properties:
+
+- reset-gpios: GPIO to generate PCIe PERST# assert and deassert signal.
+
Example:

pcie@f8050000 {
diff --git a/drivers/pci/dwc/pcie-artpec6.c b/drivers/pci/dwc/pcie-artpec6.c
index 93b3df9ed1b5..1eada6d1a381 100644
--- a/drivers/pci/dwc/pcie-artpec6.c
+++ b/drivers/pci/dwc/pcie-artpec6.c
@@ -19,6 +19,8 @@
#include <linux/interrupt.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>

#include "pcie-designware.h"

@@ -35,6 +37,7 @@ struct artpec6_pcie {
void __iomem *phy_base; /* DT phy */
enum artpec_pcie_variants variant;
enum dw_pcie_device_mode mode;
+ struct gpio_desc *reset;
};

struct artpec_pcie_of_data {
@@ -350,6 +353,13 @@ static void artpec6_pcie_deassert_core_reset(struct artpec6_pcie *artpec6_pcie)
}
artpec6_pcie_writel(artpec6_pcie, PCIECFG, val);
usleep_range(100, 200);
+
+ /* Some boards don't have PCIe reset hardwired, use a GPIO insted. */
+ if (artpec6_pcie->reset) {
+ gpiod_set_value_cansleep(artpec6_pcie->reset, 1);
+ msleep(100);
+ gpiod_set_value_cansleep(artpec6_pcie->reset, 0);
+ }
}

static void artpec6_pcie_enable_interrupts(struct artpec6_pcie *artpec6_pcie)
@@ -513,6 +523,7 @@ static int artpec6_pcie_probe(struct platform_device *pdev)
const struct artpec_pcie_of_data *data;
enum artpec_pcie_variants variant;
enum dw_pcie_device_mode mode;
+ struct device_node *node = dev->of_node;

match = of_match_device(artpec6_pcie_of_match, dev);
if (!match)
@@ -548,11 +559,18 @@ static int artpec6_pcie_probe(struct platform_device *pdev)
return PTR_ERR(artpec6_pcie->phy_base);

artpec6_pcie->regmap =
- syscon_regmap_lookup_by_phandle(dev->of_node,
+ syscon_regmap_lookup_by_phandle(node,
"axis,syscon-pcie");
if (IS_ERR(artpec6_pcie->regmap))
return PTR_ERR(artpec6_pcie->regmap);

+ artpec6_pcie->reset = devm_gpiod_get_optional(dev, "reset",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(artpec6_pcie->reset)) {
+ dev_err(dev, "Failed to request reset gpio\n");
+ return PTR_ERR(artpec6_pcie->reset);
+ }
+
platform_set_drvdata(pdev, artpec6_pcie);

switch (artpec6_pcie->mode) {
--
2.1.4
/^JN - Jesper Nilsson
--
Jesper Nilsson -- jesper.nilsson@axis.com

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