FROMLIST: PCI: Add support for PCIe WAKE# interrupt

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
@@ -586,6 +588,79 @@ int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
 	return irq_create_of_mapping(&oirq);
 }
 EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
+static void pci_configure_wake_irq(struct pci_dev *pdev, struct gpio_desc *wake)
+{
+	int ret, wake_irq;
+
+	wake_irq = gpiod_to_irq(wake);
+	if (wake_irq < 0) {
+		pci_err(pdev, "Failed to get wake irq: %d\n", wake_irq);
+		return;
+	}
+
+	/*
+	 * dev_pm_set_dedicated_wake_irq() associates a wakeup IRQ with the
+	 * device and requests it, but the PM core keeps it disabled by default.
+	 * The IRQ is enabled only when the device is allowed to wake the system
+	 * (during system suspend and after runtime suspend), and only if device
+	 * wakeup is enabled.
+	 *
+	 * When the wake IRQ fires, the wakeirq handler invokes pm_runtime_resume()
+	 * to bring the device back to an active power state (e.g. from D3cold to D0).
+	 * Once the device is active and the link is usable, the endpoint may signal
+	 * a PME, which is then handled by the PCI core (either via PME polling or the
+	 * PCIe PME service driver) to wakeup particular endpoint.
+	 */
+	ret = dev_pm_set_dedicated_wake_irq(&pdev->dev, wake_irq);
+	if (ret < 0) {
+		pci_err(pdev, "Failed to set WAKE# IRQ: %d\n", ret);
+		return;
+	}
+
+	ret = irq_set_irq_type(wake_irq, IRQ_TYPE_LEVEL_LOW);
+	if (ret < 0) {
+		dev_pm_clear_wake_irq(&pdev->dev);
+		pci_err(pdev, "Failed to set irq_type: %d\n", ret);
+		return;
+	}
+
+	device_init_wakeup(&pdev->dev, true);
+}
+
+void pci_configure_of_wake_gpio(struct pci_dev *dev)
+{
+	struct device_node *dn = pci_device_to_OF_node(dev);
+	struct gpio_desc *gpio;
+
+	if (!dn)
+		return;
+	/*
+	 * fwnode_gpiod_get() may fail with -EBUSY (e.g. shared WAKE#), but the
+	 * actual WAKE# trigger from the device would still work and the host
+	 * controller driver will enable power to the topology.
+	 *
+	 * -EPROBE_DEFER cannot be propagated here since pci_device_add() has no
+	 *  retry mechanism.
+	 */
+	gpio = fwnode_gpiod_get(of_fwnode_handle(dn), "wake", GPIOD_IN, NULL);
+	if (!IS_ERR(gpio)) {
+		dev->wake = gpio;
+		pci_configure_wake_irq(dev, gpio);
+	}
+}
+
+void pci_remove_of_wake_gpio(struct pci_dev *dev)
+{
+	struct device_node *dn = pci_device_to_OF_node(dev);
+
+	if (!dn)
+		return;
+
+	device_init_wakeup(&dev->dev, false);
+	dev_pm_clear_wake_irq(&dev->dev);
+	gpiod_put(dev->wake);
+	dev->wake = NULL;
+}
 #endif	/* CONFIG_OF_IRQ */
 
 static int pci_parse_request_of_pci_ranges(struct device *dev,

drivers/pci/pci.c

@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/msi.h>
 #include <linux/of.h>
+#include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
@@ -1128,6 +1129,16 @@ static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
 	return acpi_pci_bridge_d3(dev);
 }
 
+void platform_pci_configure_wake(struct pci_dev *dev)
+{
+	pci_configure_of_wake_gpio(dev);
+}
+
+void platform_pci_remove_wake(struct pci_dev *dev)
+{
+	pci_remove_of_wake_gpio(dev);
+}
+
 /**
  * pci_update_current_state - Read power state of given device and cache it
  * @dev: PCI device to handle.

drivers/pci/pci.h

@@ -265,6 +265,8 @@ void pci_msix_init(struct pci_dev *dev);
 bool pci_bridge_d3_possible(struct pci_dev *dev);
 void pci_bridge_d3_update(struct pci_dev *dev);
 int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type);
+void platform_pci_configure_wake(struct pci_dev *dev);
+void platform_pci_remove_wake(struct pci_dev *dev);
 
 static inline bool pci_bus_rrs_vendor_id(u32 l)
 {

drivers/pci/probe.c

@@ -2741,6 +2741,8 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 	ret = device_add(&dev->dev);
 	WARN_ON(ret < 0);
 
+	platform_pci_configure_wake(dev);
+
 	pci_npem_create(dev);
 
 	pci_doe_sysfs_init(dev);

drivers/pci/remove.c

@@ -35,6 +35,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
 	if (pci_dev_test_and_set_removed(dev))
 		return;
 
+	platform_pci_remove_wake(dev);
 	pci_doe_sysfs_teardown(dev);
 	pci_npem_remove(dev);
 

include/linux/of_pci.h

@@ -30,12 +30,18 @@ static inline void of_pci_check_probe_only(void) { }
 
 #if IS_ENABLED(CONFIG_OF_IRQ)
 int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
+void pci_configure_of_wake_gpio(struct pci_dev *dev);
+void pci_remove_of_wake_gpio(struct pci_dev *dev);
 #else
 static inline int
 of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
 {
 	return 0;
 }
+
+static inline void pci_configure_of_wake_gpio(struct pci_dev *dev) { }
+
+static inline void pci_remove_of_wake_gpio(struct pci_dev *dev) { }
 #endif
 
 #endif

include/linux/pci.h

@@ -558,6 +558,8 @@ struct pci_dev {
 	/* These methods index pci_reset_fn_methods[] */
 	u8 reset_methods[PCI_NUM_RESET_METHODS]; /* In priority order */
 
+	struct gpio_desc *wake; /* Holds WAKE# gpio */
+
 #ifdef CONFIG_PCIE_TPH
 	u16		tph_cap;	/* TPH capability offset */
 	u8		tph_mode;	/* TPH mode */