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Subject[PATCH 02/12] PCI: aardvark: add reset GPIO support
Date
The IP supports a reset GPIO. When S2RAM will be added, we must ensure
the reset line (if any) is deasserted when resuming. Add support for
it.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
drivers/pci/controller/pci-aardvark.c | 57 +++++++++++++++++++++++++++
1 file changed, 57 insertions(+)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index b95eb2aa00bb..1d31d74ddab7 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>
@@ -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"
@@ -201,6 +203,7 @@ struct advk_pcie {
u16 msi_msg;
int root_bus_nr;
struct pci_bridge_emul bridge;
+ struct gpio_desc *reset_gpio;
};

static inline void advk_writel(struct advk_pcie *pcie, u32 val, u64 reg)
@@ -973,6 +976,55 @@ static int advk_pcie_parse_request_of_pci_ranges(struct advk_pcie *pcie)
return err;
}

+static int advk_pcie_hard_reset(struct advk_pcie *pcie)
+{
+ if (!pcie->reset_gpio)
+ return -EINVAL;
+
+ gpiod_set_value_cansleep(pcie->reset_gpio, 0);
+ msleep(1);
+ gpiod_set_value_cansleep(pcie->reset_gpio, 1);
+
+ return 0;
+}
+
+static int advk_pcie_setup_reset_gpio(struct advk_pcie *pcie)
+{
+ struct device *dev = &pcie->pdev->dev;
+ enum of_gpio_flags of_flags;
+ unsigned long gpio_flags;
+ int gpio_nb;
+ int ret;
+
+ gpio_nb = of_get_named_gpio_flags(dev->of_node, "reset-gpios", 0,
+ &of_flags);
+ if (gpio_nb == -EPROBE_DEFER)
+ return gpio_nb;
+
+ /* Old bindings miss the reset GPIO handle */
+ if (!gpio_is_valid(gpio_nb)) {
+ dev_warn(dev, "Reset GPIO unavailable\n");
+ return 0;
+ }
+
+ if (of_flags & OF_GPIO_ACTIVE_LOW)
+ gpio_flags = GPIOF_ACTIVE_LOW |
+ GPIOF_OUT_INIT_LOW;
+ else
+ gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+ ret = devm_gpio_request_one(dev, gpio_nb, gpio_flags,
+ "pcie-aardvark-reset");
+ if (ret) {
+ dev_err(dev, "Failed to retrieve reset GPIO (%d)\n", ret);
+ return ret;
+ }
+
+ pcie->reset_gpio = gpio_to_desc(gpio_nb);
+
+ return 0;
+}
+
static int advk_pcie_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1008,6 +1060,11 @@ static int advk_pcie_probe(struct platform_device *pdev)
return ret;
}

+ ret = advk_pcie_setup_reset_gpio(pcie);
+ if (ret)
+ return ret;
+
+ advk_pcie_hard_reset(pcie);
advk_pcie_setup_hw(pcie);

advk_sw_pci_bridge_init(pcie);
--
2.19.1
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