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 |  6 +++++
 3 files changed, 72 insertions(+)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 7a806f5c0d201bc322d4a53d6ac47cab2cd28c55..abb0ba001edf604170aaa118f7fdc1a1709c171f 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
@@ -851,3 +853,61 @@ 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 01e51db8d285af54673db3ea526ceda073c94ec9..6e3d90db4b2505dd3885b482d4c5eafa033714e7 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -820,6 +820,9 @@ 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);
 
@@ -863,6 +866,9 @@ 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 02e73099bad0532466fa10f549cc3c5013aa1bbb..fe1da757e9eca0f82ae0d8043c0e4547ac9c30b6 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -695,6 +695,10 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
 	if (type == PCI_EXP_TYPE_RC_EC)
 		pcie_link_rcec(dev);
 
+	status = of_pci_setup_wake_irq(dev);
+	if (status)
+		return status;
+
 	status = pcie_port_device_register(dev);
 	if (status)
 		return status;
@@ -728,6 +732,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
 		pm_runtime_dont_use_autosuspend(&dev->dev);
 	}
 
+	of_pci_teardown_wake_irq(dev);
+
 	pcie_port_device_remove(dev);
 
 	pci_disable_device(dev);

-- 
2.34.1

On 4/1/2025 10:12 AM, Krishna Chaitanya Chundru wrote:
> 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 |  6 +++++
>   3 files changed, 72 insertions(+)
> 
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index 7a806f5c0d201bc322d4a53d6ac47cab2cd28c55..abb0ba001edf604170aaa118f7fdc1a1709c171f 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
> @@ -851,3 +853,61 @@ 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 01e51db8d285af54673db3ea526ceda073c94ec9..6e3d90db4b2505dd3885b482d4c5eafa033714e7 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -820,6 +820,9 @@ 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);
>   
> @@ -863,6 +866,9 @@ 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 02e73099bad0532466fa10f549cc3c5013aa1bbb..fe1da757e9eca0f82ae0d8043c0e4547ac9c30b6 100644
> --- a/drivers/pci/pcie/portdrv.c
> +++ b/drivers/pci/pcie/portdrv.c
> @@ -695,6 +695,10 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
>   	if (type == PCI_EXP_TYPE_RC_EC)
>   		pcie_link_rcec(dev);
>   
> +	status = of_pci_setup_wake_irq(dev);
> +	if (status)
> +		return status;
> +
>   	status = pcie_port_device_register(dev);
>   	if (status)
>   		return status;
> @@ -728,6 +732,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
>   		pm_runtime_dont_use_autosuspend(&dev->dev);
>   	}
>   
> +	of_pci_teardown_wake_irq(dev);
> +
>   	pcie_port_device_remove(dev);
>   
>   	pci_disable_device(dev);
> 
we need to teardown the wake irq in shutdown also, I will add it in the
next patch.

- Krishna Chaitanya.

On Tue, Apr 01, 2025 at 10:12:44AM +0530, Krishna Chaitanya Chundru wrote:
> 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.
[...]
> --- a/drivers/pci/pcie/portdrv.c
> +++ b/drivers/pci/pcie/portdrv.c
> @@ -695,6 +695,10 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
>  	if (type == PCI_EXP_TYPE_RC_EC)
>  		pcie_link_rcec(dev);
>  
> +	status = of_pci_setup_wake_irq(dev);
> +	if (status)
> +		return status;
> +
>  	status = pcie_port_device_register(dev);
>  	if (status)
>  		return status;
> @@ -728,6 +732,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
>  		pm_runtime_dont_use_autosuspend(&dev->dev);
>  	}
>  
> +	of_pci_teardown_wake_irq(dev);
> +
>  	pcie_port_device_remove(dev);
>  
>  	pci_disable_device(dev);

Why doesn't the teardown order mirror the probe order, i.e. why is
of_pci_teardown_wake_irq() called *before* pcie_port_device_remove()
instead of after?

(pcie_port_device_remove() is the opposite of pcie_port_device_register().)

Also, why is it safe to bail out of probe on failure of
of_pci_setup_wake_irq() without unwinding whatever pcie_link_rcec()
has done?  I think this needs either an explanation or reordering.

Thanks,

Lukas

On 4/1/2025 12:31 PM, Lukas Wunner wrote:
> On Tue, Apr 01, 2025 at 10:12:44AM +0530, Krishna Chaitanya Chundru wrote:
>> 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.
> [...]
>> --- a/drivers/pci/pcie/portdrv.c
>> +++ b/drivers/pci/pcie/portdrv.c
>> @@ -695,6 +695,10 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
>>   	if (type == PCI_EXP_TYPE_RC_EC)
>>   		pcie_link_rcec(dev);
>>   
>> +	status = of_pci_setup_wake_irq(dev);
>> +	if (status)
>> +		return status;
>> +
>>   	status = pcie_port_device_register(dev);
>>   	if (status)
>>   		return status;
>> @@ -728,6 +732,8 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
>>   		pm_runtime_dont_use_autosuspend(&dev->dev);
>>   	}
>>   
>> +	of_pci_teardown_wake_irq(dev);
>> +
>>   	pcie_port_device_remove(dev);
>>   
>>   	pci_disable_device(dev);
> 
> Why doesn't the teardown order mirror the probe order, i.e. why is
> of_pci_teardown_wake_irq() called *before* pcie_port_device_remove()
> instead of after?
> 
ack, in the next patch I will move teardown after
pcie_port_device_remove()
> (pcie_port_device_remove() is the opposite of pcie_port_device_register().)
> 
> Also, why is it safe to bail out of probe on failure of
> of_pci_setup_wake_irq() without unwinding whatever pcie_link_rcec()
> has done?  I think this needs either an explanation or reordering.
> 
if there is a failure in port_device_register also we are not unwinding
so I taught it is already taken care. Looks like it is not.

In the next patch I will move of_pci_setup_wake_irq() above 
pcie_link_rcec() to avoid all this.

- Krishna Chaitanya.

> Thanks,
> 
> Lukas