Re: [PATCH v2 2/2] PCI: Add support for PCIe wake interrupt

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

On 6/1/2025 8:51 PM, Manivannan Sadhasivam wrote:
> On Sat, Apr 19, 2025 at 11:13:04AM +0530, Krishna Chaitanya Chundru wrote:
> 
> Subject prefix should be 'PCI/portdrv'
> 
>> 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 | 12 +++++++++-
>>   3 files changed, 77 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
>> index ab7a8252bf4137a17971c3eb8ab70ce78ca70969..13623797c88a03dfb9d9079518d87a5e1e68df38 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
>> @@ -966,3 +968,61 @@ 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
> 
> This function is for setting up the wake interrupt for slot, not for endpoint
> devices, isn't it? Then it should be named as such:
> 
> 	of_pci_slot_setup_wake_irq()
> 
>> + * @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
> 
> s/GPIO pin/WAKE# GPIO
> 
>> + * dedicated wake interrupt.
>> + *
>> + * Return: 0 if the wake gpio is not available or successfully parsed else
> 
> s/wake gpio/WAKE# GPIO
> 
>> + * 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");
> 
> WAKE# is an optional GPIO. So the driver should not warn users if it is not
> defined in the root port node. It should however print the error log and return
> errno, if the API returns other than -ENOENT.
> 
>> +		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
> 
> Same comment as above.
> 
>> + *
>> + * @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 b81e99cd4b62a3022c8b07a09f212f6888674487..b2f65289f4156fa1851c2d2f20c4ca948f36258f 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -888,6 +888,9 @@ 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);
>>   
>> @@ -931,6 +934,9 @@ 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) { }
>> +
> 
> Provide stub for these APIs if CONFIG_OF is not enabled.
> 
These are the stub functions when CONFIG_OF is not enabled.

- Krishna Chaitanya.
> - Mani
>