Re: [PATCH v2 09/17] xen/arm: Add support for PCI init to initialize the PCI driver.

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 22 Sep 2021, Rahul Singh wrote:
> pci_init(..) will be called during xen startup to initialize and probe
> the PCI host-bridge driver.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
> ---
> Change in v2:
> - ACPI init function to return int
> - pci_segments_init() called before dt/acpi init
> ---
>  xen/arch/arm/pci/pci.c       | 54 ++++++++++++++++++++++++++++++++++++
>  xen/include/asm-arm/device.h |  1 +
>  2 files changed, 55 insertions(+)
> 
> diff --git a/xen/arch/arm/pci/pci.c b/xen/arch/arm/pci/pci.c
> index a7a7bc3213..71fa532842 100644
> --- a/xen/arch/arm/pci/pci.c
> +++ b/xen/arch/arm/pci/pci.c
> @@ -12,6 +12,10 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <xen/acpi.h>
> +#include <xen/device_tree.h>
> +#include <xen/errno.h>
> +#include <xen/init.h>
>  #include <xen/pci.h>
>  
>  /*
> @@ -22,6 +26,56 @@ int arch_pci_clean_pirqs(struct domain *d)
>      return 0;
>  }
>  
> +static int __init dt_pci_init(void)
> +{
> +    struct dt_device_node *np;
> +    int rc;
> +
> +    dt_for_each_device_node(dt_host, np)
> +    {
> +        rc = device_init(np, DEVICE_PCI, NULL);
> +        if( !rc )
> +            continue;

This is a NIT, so feel free to code it as you prefer, but I would write
it as follows for simplicity:


/* comment about EBADF and ENODEV */
if ( !rc || rc == -EBADF || rc == -ENODEV )
    continue;
return rc;


> +        /*
> +         * Ignore the following error codes:
> +         *   - EBADF: Indicate the current is not an pci
                                             ^ device ^a   ^ device


> +         *   - ENODEV: The pci device is not present or cannot be used by
> +         *     Xen.
> +         */
> +        else if ( rc != -EBADF && rc != -ENODEV )
> +        {
> +            printk(XENLOG_ERR "No driver found in XEN or driver init 
> error.\n");
> +            return rc;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +#ifdef CONFIG_ACPI
> +static int __init acpi_pci_init(void)
> +{
> +    printk(XENLOG_ERR "ACPI pci init not supported \n");
> +    return 0;

Should return ENOSYS or EOPNOTSUPP?


> +}
> +#else
> +static inline int __init acpi_pci_init(void)

Not sure I would inline it but OK either way


> +{
> +    return -EINVAL;
> +}
> +#endif
> +
> +static int __init pci_init(void)
> +{
> +    pci_segments_init();
> +
> +    if ( acpi_disabled )
> +        return dt_pci_init();
> +    else
> +        return acpi_pci_init();
> +}
> +__initcall(pci_init);
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/asm-arm/device.h b/xen/include/asm-arm/device.h
> index ee7cff2d44..5ecd5e7bd1 100644
> --- a/xen/include/asm-arm/device.h
> +++ b/xen/include/asm-arm/device.h
> @@ -34,6 +34,7 @@ enum device_class
>      DEVICE_SERIAL,
>      DEVICE_IOMMU,
>      DEVICE_GIC,
> +    DEVICE_PCI,
>      /* Use for error */
>      DEVICE_UNKNOWN,
>  };
> -- 
> 2.17.1
>