Re: [Xen-devel] [PATCH 5/6] xen/device_tree: introduce find_compatible_node

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-12-05 at 18:19 +0000, Stefano Stabellini wrote:
> Introduce a find_compatible_node function that can be used by device
> drivers to find the node corresponding to their device in the device
> tree.
> 
> Also add device_tree_node_compatible to device_tree.h, that is currently
> missing.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  xen/arch/arm/setup.c          |    2 +-
>  xen/common/device_tree.c      |   47 
> +++++++++++++++++++++++++++++++++++++++++
>  xen/include/xen/device_tree.h |    3 ++
>  3 files changed, 51 insertions(+), 1 deletions(-)
> 
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index 5f4e318..d978938 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -187,7 +187,7 @@ void __init start_xen(unsigned long boot_phys_offset,
>  
>      smp_clear_cpu_maps();
>  
> -    fdt = (void *)BOOT_MISC_VIRT_START
> +    device_tree_flattened = fdt = (void *)BOOT_MISC_VIRT_START

This seems unrelated to the commit log?

Is this to avoid declaring an early variant? It seems like this could
mean we can drop the fdt variable from a bunch of the existing early_*
functions.

>          + (atag_paddr & ((1 << SECOND_SHIFT) - 1));
>      fdt_size = device_tree_early_init(fdt);
>  
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 8d5b6b0..ca0aba7 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -173,6 +173,53 @@ int device_tree_for_each_node(const void *fdt,
>      return 0;
>  }
>  
> +struct find_compat {
> +    const char *compatible;
> +    int found;
> +    int node;
> +    int depth;
> +    u32 address_cells;
> +    u32 size_cells;
> +};
> +
> +static int _find_compatible_node(const void *fdt,
> +                             int node, const char *name, int depth,
> +                             u32 address_cells, u32 size_cells,
> +                             void *data)
> +{
> +    struct find_compat *c = (struct find_compat *) data;

Do you want 
        if ( c->found ) 
                return ?

> +    if ( device_tree_node_compatible(fdt, node, c->compatible) )
> +    {
> +        c->found = 1;
> +        c->node = node;
> +        c->depth = depth;
> +        c->address_cells = address_cells;
> +        c->size_cells = size_cells;
> +    }
> +    return 0;
> +}
> + 
> +int find_compatible_node(const char *compatible, int *node, int *depth,
> +                u32 *address_cells, u32 *size_cells)
> +{
> +    int ret;
> +    struct find_compat c;
> +    c.compatible = compatible;
> +    c.found = 0;
> +
> +    ret = device_tree_for_each_node(device_tree_flattened, 
> _find_compatible_node, &c);
> +    if ( !c.found )
> +        return ret;
> +    else
> +    {
> +        *node = c.node;
> +        *depth = c.depth;
> +        *address_cells = c.address_cells;
> +        *size_cells = c.size_cells;
> +        return 1;
> +    }
> +}
> +
>  /**
>   * device_tree_bootargs - return the bootargs (the Xen command line)
>   * @fdt flat device tree.
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index a0e3a97..5a75f0e 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -54,6 +54,9 @@ void device_tree_set_reg(u32 **cell, u32 address_cells, u32 
> size_cells,
>                           u64 start, u64 size);
>  u32 device_tree_get_u32(const void *fdt, int node, const char *prop_name);
>  bool_t device_tree_node_matches(const void *fdt, int node, const char 
> *match);
> +bool_t device_tree_node_compatible(const void *fdt, int node, const char 
> *match);
> +int find_compatible_node(const char *compatible, int *node, int *depth,
> +                u32 *address_cells, u32 *size_cells);
>  int device_tree_for_each_node(const void *fdt,
>                                device_tree_node_func func, void *data);
>  const char *device_tree_bootargs(const void *fdt);



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