Re: [PATCH v2 08/17] xen/device-tree: Add dt_get_pci_domain_nr helper

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 22 Sep 2021, Rahul Singh wrote:
> Based on tag Linux v5.14.2 commit bbdd3de144fc142f2f4b9834c9241cc4e7f3d3fc

Please use an upstream commit id


> Import the Linux helper of_get_pci_domain_nr. This function will try to
> obtain the host bridge domain number by finding a property called
> "linux,pci-domain" of the given device node.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
> ---
> Change in v2: Patch introduced in v2
> ---
>  xen/common/device_tree.c      | 12 ++++++++++++
>  xen/include/xen/device_tree.h | 19 +++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 53160d61f8..ea93da1725 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -2183,6 +2183,18 @@ void __init dt_unflatten_host_device_tree(void)
>      dt_alias_scan();
>  }
>  
> +int dt_get_pci_domain_nr(struct dt_device_node *node)
> +{
> +    u32 domain;
> +    int error;
> +
> +    error = dt_property_read_u32(node, "linux,pci-domain", &domain);
> +    if ( !error )
> +        return -EINVAL;
> +
> +    return (u16)domain;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index 497144b8a7..9069040ef7 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -831,6 +831,25 @@ int dt_count_phandle_with_args(const struct 
> dt_device_node *np,
>                                 const char *list_name,
>                                 const char *cells_name);
>  
> +/**
> + * dt_get_pci_domain_nr - Find the host bridge domain number
> + *            of the given device node.
> + * @node: Device tree node with the domain information.
> + *
> + * This function will try to obtain the host bridge domain number by finding
> + * a property called "linux,pci-domain" of the given device node.
> + *
> + * Return:
> + * * > 0    - On success, an associated domain number.
> + * * -EINVAL    - The property "linux,pci-domain" does not exist.
> + * * -ENODATA   - The linux,pci-domain" property does not have value.
> + * * -EOVERFLOW - Invalid "linux,pci-domain" property value.

This doesn't match reality for us because it can only return EINVAL


> + * Returns the associated domain number from DT in the range [0-0xffff], or
> + * a negative value if the required property is not found.
> + */
> +int dt_get_pci_domain_nr(struct dt_device_node *node);
> +
>  #ifdef CONFIG_DEVICE_TREE_DEBUG
>  #define dt_dprintk(fmt, args...)  \
>      printk(XENLOG_DEBUG fmt, ## args)
> -- 
> 2.17.1
>