Re: [PATCH v3 1/2] PCI/portdrv: Add option to setup IRQs for platform-specific Service Errors

["Pali Rohár" <pali@kernel.org>]

On Thursday 13 January 2022 11:49:38 Stefan Roese wrote:
> From: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
> 
> As per section 6.2.4.1.2, 6.2.6 in PCIe r4.0 (and later versions),
> platform-specific System Errors like AER can be delivered via platform-
> specific interrupt lines.
> 
> This patch adds the init_platform_service_irqs() hook to struct
> pci_host_bridge, making it possible that platforms may implement this
> function to hook IRQs for these platform-specific System Errors, like
> AER.
> 
> If these platform-specific service IRQs have been successfully
> installed via pcie_init_platform_service_irqs(),
> pcie_init_service_irqs() is skipped.
> 
> Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
> Signed-off-by: Stefan Roese <sr@denx.de>
> Cc: Bjorn Helgaas <helgaas@kernel.org>
> Cc: Pali Rohár <pali@kernel.org>
> Cc: Michal Simek <michal.simek@xilinx.com>
> ---
>  drivers/pci/pcie/portdrv_core.c | 43 ++++++++++++++++++++++++++++++++-
>  include/linux/pci.h             |  2 ++
>  2 files changed, 44 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> index bda630889f95..4dab74ff4368 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -190,6 +190,31 @@ static int pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
>  	return 0;
>  }
>  
> +/**
> + * pcie_init_platform_service_irqs - initialize platform service irqs for
> + * platform-specific System Errors
> + * @dev: PCI Express port to handle
> + * @irqs: Array of irqs to populate
> + * @mask: Bitmask of capabilities
> + *
> + * Return value: true/false for platforms service irqs installed or not
> + */
> +static bool pcie_init_platform_service_irqs(struct pci_dev *dev,
> +					    int *irqs, int mask)
> +{
> +	struct pci_host_bridge *bridge;
> +
> +	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {

I think that this check is not needed as it is done before calling
pcie_init_platform_service_irqs() function.

> +		bridge = pci_find_host_bridge(dev->bus);
> +		if (bridge && bridge->init_platform_service_irqs) {
> +			bridge->init_platform_service_irqs(dev, irqs, mask);
> +			return true;

Suggestion: What about "return bridge->init_platform_service_irqs(...);" ?
This could allow callback function to fail...

> +		}
> +	}
> +
> +	return false;
> +}
> +
>  /**
>   * get_port_device_capability - discover capabilities of a PCI Express port
>   * @dev: PCI Express port to examine
> @@ -318,6 +343,7 @@ int pcie_port_device_register(struct pci_dev *dev)
>  	int irqs[PCIE_PORT_DEVICE_MAXSERVICES] = {
>  		[0 ... PCIE_PORT_DEVICE_MAXSERVICES-1] = -1
>  	};
> +	bool plat_irqs;
>  
>  	/* Enable PCI Express port device */
>  	status = pci_enable_device(dev);
> @@ -342,7 +368,22 @@ int pcie_port_device_register(struct pci_dev *dev)
>  		irq_services |= PCIE_PORT_SERVICE_DPC;
>  	irq_services &= capabilities;
>  
> -	if (irq_services) {
> +	/*
> +	 * Some platforms have dedicated interrupts from root complex to
> +	 * interrupt controller for PCIe platform-specific System Errors
> +	 * like AER/PME etc., check if the platform registered with any such
> +	 * IRQ.
> +	 */
> +	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
> +		plat_irqs = pcie_init_platform_service_irqs(dev, irqs,
> +							    capabilities);
> +	}
> +
> +	/*
> +	 * Only install service irqs, when the platform-specific hook was
> +	 * unsuccessful
> +	 */
> +	if (irq_services && !plat_irqs) {
>  		/*
>  		 * Initialize service IRQs. Don't use service devices that
>  		 * require interrupts if there is no way to generate them.
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 18a75c8e615c..a0bcc8062b91 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -554,6 +554,8 @@ struct pci_host_bridge {
>  	u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */
>  	int (*map_irq)(const struct pci_dev *, u8, u8);
>  	void (*release_fn)(struct pci_host_bridge *);
> +	void (*init_platform_service_irqs)(struct pci_dev *dev, int *irqs,
> +					   int plat_mask);
>  	void		*release_data;
>  	unsigned int	ignore_reset_delay:1;	/* For entire hierarchy */
>  	unsigned int	no_ext_tags:1;		/* No Extended Tags */
> -- 
> 2.34.1
>