Re: [PATCH v8 3/3] PCI: Add support for PCIe WAKE# interrupt
From: Krishna Chaitanya Chundru
Date: Tue Mar 24 2026 - 08:13:44 EST
On 3/17/2026 12:56 PM, Manivannan Sadhasivam wrote:
On Fri, Mar 13, 2026 at 12:38:42PM +0530, Krishna Chaitanya Chundru wrote:ack.
According to the PCI Express specification (PCIe r7.0, Section 5.3.3.2),Just set wakeup only if dev_pm_set_dedicated_shared_wake_irq() succeeds.
two link wakeup mechanisms are defined: Beacon and WAKE#. Beacon is a
hardware-only mechanism and is invisible to software (PCIe r7.0,
Section 4.2.7.8.1). This change adds support for the WAKE# mechanism in
the PCI core.
According to the PCIe specification, multiple WAKE# signals can exist in
a system or each component in the hierarchy could share a single WAKE#
signal. 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 in sec
5.3.3.2, WAKE# can also be terminated at the switch itself. To support
this, the WAKE# should be described in the device tree node of the
endpoint/bridge. If all endpoints share a single WAKE# line, then each
endpoint node should describe the same WAKE# signal or a single WAKE# in
the Root Port node.
In pci_device_add(), PCI framework will search for the WAKE# in device
node, If not found, it searches in its upstream port only if upstream port
is Root Port. Once found, register for the wake IRQ in shared mode, as the
WAKE# may be shared among multiple endpoints.
dev_pm_set_dedicated_shared_wake_irq() associates a wakeup IRQ with a
device and requests it, but the PM core keeps the IRQ disabled by default.
The IRQ is enabled only when the device is permitted to wake the system,
i.e. during system suspend and after runtime suspend, and only when 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, such as transitioning from
D3cold to D0. Once the device is active and the link is usable, the
endpoint may generate a PME, which is then handled by the PCI core through
PME polling or the PCIe PME service driver to complete the wakeup of the
endpoint.
WAKE# is added in dts schema and merged based on below links.
Link: https://lore.kernel.org/all/20250515090517.3506772-1-krishna.chundru@xxxxxxxxxxxxxxxx/
Link: https://github.com/devicetree-org/dt-schema/pull/170
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>
---
drivers/pci/of.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.c | 10 +++++++
drivers/pci/pci.h | 2 ++
drivers/pci/probe.c | 2 ++
drivers/pci/remove.c | 1 +
include/linux/of_pci.h | 4 +++
include/linux/pci.h | 2 ++
7 files changed, 95 insertions(+)
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 9f8eb5df279ed28db7a3b2fd29c65da9975c2efa..b7199d3598b31b62245716c178a5a73565efc89e 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 +588,78 @@ 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;
+ }
+
+ device_init_wakeup(&pdev->dev, true);
Ack. I will change IRQ_TYPE_EDGE_FALLING to IRQ_TYPE_LEVEL_LOW.+Isn't WAKE# a level triggered signal?
+ /*
+ * dev_pm_set_dedicated_shared_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_shared_wake_irq(&pdev->dev, wake_irq,
+ IRQ_TYPE_EDGE_FALLING);
ack.+ if (ret < 0) {s/wake/WAKE#
+ pci_err(pdev, "Failed to set wake IRQ: %d\n", ret);
- Krishna Chaitanya.
- Mani