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Message-Id: <20251107-wakeirq_support-v5-2-464e17f2c20c@oss.qualcomm.com>
Date: Fri, 07 Nov 2025 14:52:25 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
Pavel Machek <pavel@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Danilo Krummrich <dakr@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, linux-gpio@...r.kernel.org,
quic_vbadigan@...cinc.com, quic_mrana@...cinc.com, sherry.sun@....com,
Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: [PATCH v5 2/2] PCI: Add support for PCIe WAKE# interrupt
According to the PCIe specification 6, sec 5.3.3.2, there are two defined
wakeup mechanisms: Beacon and WAKE# for the Link wakeup mechanisms to
provide a means of signaling the platform to re-establish power and
reference clocks to the components within its domain. Beacon is a hardware
mechanism invisible to software (PCIe r7.0, sec 4.2.7.8.1). Adding WAKE#
support in PCI framework.
According to the PCIe specification, multiple WAKE# signals can exist in
a system. In configurations involving a PCIe switch, each downstream port
(DSP) of the switch may be connected to a separate WAKE# line, allowing
each endpoint to signal WAKE# independently. From figure 5.4, WAKE# can
also be terminated at the switch itself. To support this, the WAKE#
should be described in the device tree node of the endpint/bridge. If all
endpoints share a single WAKE# line, then WAKE# should be defined in the
each node.
To support legacy devicetree in direct attach case, driver will search
in root port node for WAKE# if the driver doesn't find in the endpoint
node.
In pci_device_add(), PCI framework will search for the WAKE# in its node,
If not found, it searches in its upstream port only if upstream port is
root port to support legacy bindings. Once found, register for the wake IRQ
in shared mode, as the WAKE# may be shared among multiple endpoints.
When the IRQ is asserted, the handle_threaded_wake_irq() handler triggers
a pm_runtime_resume(). The PM framework ensures that the parent device is
resumed before the child i.e controller driver which can bring back device
state to D0.
WAKE# is added in dts schema and merged based on below links.
Link: https://lore.kernel.org/all/20250515090517.3506772-1-krishna.chundru@oss.qualcomm.com/
Link: https://github.com/devicetree-org/dt-schema/pull/170
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
drivers/pci/of.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 6 ++++++
drivers/pci/probe.c | 2 ++
drivers/pci/remove.c | 1 +
include/linux/pci.h | 2 ++
5 files changed, 69 insertions(+)
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 3579265f119845637e163d9051437c89662762f8..8cb103d18687e16d7283510544fa640abee68d29 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
@@ -586,6 +588,62 @@ 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;
+
+ if (!wake)
+ return;
+
+ wake_irq = gpiod_to_irq(wake);
+ if (wake_irq < 0) {
+ dev_err(&pdev->dev, "Failed to get wake irq: %d\n", wake_irq);
+ return;
+ }
+
+ device_init_wakeup(&pdev->dev, true);
+
+ ret = dev_pm_set_dedicated_wake_irq_flags(&pdev->dev, wake_irq,
+ IRQF_SHARED | IRQ_TYPE_EDGE_FALLING);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Failed to set wake IRQ: %d\n", ret);
+ device_init_wakeup(&pdev->dev, false);
+ }
+}
+
+void pci_configure_of_wake_gpio(struct pci_dev *dev)
+{
+ struct device_node *dn = pci_device_to_OF_node(dev);
+ struct gpio_desc *gpio;
+ struct pci_dev *root;
+
+ if (!dn)
+ return;
+
+ gpio = fwnode_gpiod_get_index(of_fwnode_handle(dn),
+ "wake", 0, GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE, NULL);
+ if (IS_ERR(gpio)) {
+ /*
+ * To support legacy devicetree, search in root port for WAKE#
+ * in direct attach case.
+ */
+ root = pci_upstream_bridge(dev);
+ if (pci_is_root_bus(root->bus))
+ pci_configure_wake_irq(dev, root->wake);
+ } else {
+ dev->wake = gpio;
+ pci_configure_wake_irq(dev, gpio);
+ }
+}
+
+void pci_remove_of_wake_gpio(struct pci_dev *dev)
+{
+ dev_pm_clear_wake_irq(&dev->dev);
+ device_init_wakeup(&dev->dev, false);
+ gpiod_put(dev->wake);
+ dev->wake = NULL;
+}
#endif /* CONFIG_OF_IRQ */
static int pci_parse_request_of_pci_ranges(struct device *dev,
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4492b809094b5794bd94dfbc20102cb208c3fa2f..05cb240ecdb59f9833ca6dae2357fdbd012195d6 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -1056,6 +1056,9 @@ 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);
+void pci_configure_of_wake_gpio(struct pci_dev *dev);
+void pci_remove_of_wake_gpio(struct pci_dev *dev);
+
int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge);
bool of_pci_supply_present(struct device_node *np);
int of_pci_get_equalization_presets(struct device *dev,
@@ -1101,6 +1104,9 @@ static inline int devm_of_pci_bridge_init(struct device *dev, struct pci_host_br
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) { }
+
static inline bool of_pci_supply_present(struct device_node *np)
{
return false;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 0ce98e18b5a876afe72af35a9f4a44d598e8d500..f9b879c8e3f72a9845f60577335019aa2002dc23 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2762,6 +2762,8 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
ret = device_add(&dev->dev);
WARN_ON(ret < 0);
+ pci_configure_of_wake_gpio(dev);
+
pci_npem_create(dev);
pci_doe_sysfs_init(dev);
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index ce5c25adef5518e5aec30c41de37ea66d682f3b0..26e9c1df51c76344a1d7f5cc7edd433780e73474 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -54,6 +54,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
if (pci_dev_test_and_set_removed(dev))
return;
+ pci_remove_of_wake_gpio(dev);
pci_doe_sysfs_teardown(dev);
pci_npem_remove(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d1fdf81fbe1e427aecbc951fa3fdf65c20450b05..cd7b5eb82a430ead2f64d903a24a5b06a1b7b17e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -555,6 +555,8 @@ 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 */
--
2.34.1
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