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

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

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.