Re: [Qemu-devel] [PATCH 07/25] dt: add helper for phandle allocation

[Scott Wood]

On 05/30/2012 06:00 AM, Alexander Graf wrote:
> Phandle references work by having 2 pieces:
> 
>   - a "phandle" 1-cell property in the device tree node
>   - a reference to the same value in a property we want to point
>     to the other node
> 
> To generate the 1-cell property, we need an allocation mechanism that
> gives us a unique number space. This patch adds an allocator for these
> properties.
> 
> Signed-off-by: Alexander Graf <address@hidden>
> ---
>  device_tree.c |    7 +++++++
>  device_tree.h |    1 +
>  2 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/device_tree.c b/device_tree.c
> index d4f1f0a..317bdd0 100644
> --- a/device_tree.c
> +++ b/device_tree.c
> @@ -220,6 +220,13 @@ int qemu_devtree_setprop_phandle(void *fdt, const char 
> *node_path,
>      return qemu_devtree_setprop_cell(fdt, node_path, property, phandle);
>  }
>  
> +uint32_t qemu_devtree_alloc_phandle(void *fdt)
> +{
> +    static int phandle = 0x8000;
> +
> +    return phandle++;
> +}

An external configuration tool may want to use dumpdtb/dtb to merge in
nodes from other sources (e.g. the host device tree), which may have
unchangeable phandles that conflict with these.

It would be nice if the starting point could be overridden on the
command line.  This can be a TODO for later, of course.

-Scott