[PATCH v2 2/2] PCI: Add support for PCIe wake interrupt

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

PCIe wake interrupt is needed for bringing back PCIe device state
from D3cold to D0.

Implement new functions, of_pci_setup_wake_irq() and
of_pci_teardown_wake_irq(), to manage wake interrupts for PCI devices
using the Device Tree.

From the port bus driver call these functions to enable wake support
for bridges.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/pci/of.c           | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h          |  6 +++++
 drivers/pci/pcie/portdrv.c | 12 +++++++++-
 3 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index ab7a8252bf4137a17971c3eb8ab70ce78ca70969..13623797c88a03dfb9d9079518d87a5e1e68df38 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -7,6 +7,7 @@
 #define pr_fmt(fmt)	"PCI: OF: " fmt
 
 #include <linux/cleanup.h>
+#include <linux/gpio/consumer.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
@@ -15,6 +16,7 @@
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
 #include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
 #include "pci.h"
 
 #ifdef CONFIG_PCI
@@ -966,3 +968,61 @@ u32 of_pci_get_slot_power_limit(struct device_node *node,
 	return slot_power_limit_mw;
 }
 EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
+
+/**
+ * of_pci_setup_wake_irq - Set up wake interrupt for PCI device
+ * @pdev: The PCI device structure
+ *
+ * This function sets up the wake interrupt for a PCI device by getting the
+ * corresponding GPIO pin from the device tree, and configuring it as a
+ * dedicated wake interrupt.
+ *
+ * Return: 0 if the wake gpio is not available or successfully parsed else
+ * errno otherwise.
+ */
+int of_pci_setup_wake_irq(struct pci_dev *pdev)
+{
+	struct gpio_desc *wake;
+	struct device_node *dn;
+	int ret, wake_irq;
+
+	dn = pci_device_to_OF_node(pdev);
+	if (!dn)
+		return 0;
+
+	wake = devm_fwnode_gpiod_get(&pdev->dev, of_fwnode_handle(dn),
+				     "wake", GPIOD_IN, NULL);
+	if (IS_ERR(wake)) {
+		dev_warn(&pdev->dev, "Cannot get wake GPIO\n");
+		return 0;
+	}
+
+	wake_irq = gpiod_to_irq(wake);
+	device_init_wakeup(&pdev->dev, true);
+
+	ret = dev_pm_set_dedicated_wake_irq(&pdev->dev, wake_irq);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to set wake IRQ: %d\n", ret);
+		device_init_wakeup(&pdev->dev, false);
+		return ret;
+	}
+	irq_set_irq_type(wake_irq, IRQ_TYPE_EDGE_FALLING);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_pci_setup_wake_irq);
+
+/**
+ * of_pci_teardown_wake_irq - Teardown wake interrupt setup for PCI device
+ *
+ * @pdev: The PCI device structure
+ *
+ * This function tears down the wake interrupt setup for a PCI device,
+ * clearing the dedicated wake interrupt and disabling device wake-up.
+ */
+void of_pci_teardown_wake_irq(struct pci_dev *pdev)
+{
+	dev_pm_clear_wake_irq(&pdev->dev);
+	device_init_wakeup(&pdev->dev, false);
+}
+EXPORT_SYMBOL_GPL(of_pci_teardown_wake_irq);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index b81e99cd4b62a3022c8b07a09f212f6888674487..b2f65289f4156fa1851c2d2f20c4ca948f36258f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -888,6 +888,9 @@ void pci_release_of_node(struct pci_dev *dev);
 void pci_set_bus_of_node(struct pci_bus *bus);
 void pci_release_bus_of_node(struct pci_bus *bus);
 
+int of_pci_setup_wake_irq(struct pci_dev *pdev);
+void of_pci_teardown_wake_irq(struct pci_dev *pdev);
+
 int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge);
 bool of_pci_supply_present(struct device_node *np);
 
@@ -931,6 +934,9 @@ static inline int devm_of_pci_bridge_init(struct device *dev, struct pci_host_br
 	return 0;
 }
 
+static int of_pci_setup_wake_irq(struct pci_dev *pdev) { return 0; }
+static void of_pci_teardown_wake_irq(struct pci_dev *pdev) { }
+
 static inline bool of_pci_supply_present(struct device_node *np)
 {
 	return false;
diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index e8318fd5f6ed537a1b236a3a0f054161d5710abd..33220ecf821c348d49782855eb5aa3f2fe5c335e 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -694,12 +694,18 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
 	     (type != PCI_EXP_TYPE_RC_EC)))
 		return -ENODEV;
 
+	status = of_pci_setup_wake_irq(dev);
+	if (status)
+		return status;
+
 	if (type == PCI_EXP_TYPE_RC_EC)
 		pcie_link_rcec(dev);
 
 	status = pcie_port_device_register(dev);
-	if (status)
+	if (status) {
+		of_pci_teardown_wake_irq(dev);
 		return status;
+	}
 
 	pci_save_state(dev);
 
@@ -732,6 +738,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
 
 	pcie_port_device_remove(dev);
 
+	of_pci_teardown_wake_irq(dev);
+
 	pci_disable_device(dev);
 }
 
@@ -744,6 +752,8 @@ static void pcie_portdrv_shutdown(struct pci_dev *dev)
 	}
 
 	pcie_port_device_remove(dev);
+
+	of_pci_teardown_wake_irq(dev);
 }
 
 static pci_ers_result_t pcie_portdrv_error_detected(struct pci_dev *dev,

-- 
2.34.1