Re: [Qemu-ppc] [Qemu-devel] [PATCH 07/31] dt: add helper for phandle allocation

[Peter Crosthwaite]

On Wed, 2012-06-06 at 01:52 +0200, 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;

can easily double check for duplicates. Would also allow you to start
from 1 rather than magic number 0x8000?

while (fdt_node_offset_by_phandle(fdt, phandle) != FDT_ERR_NOTFOUND)
    phandle++;

> +
> +    return phandle++;
> +}
> +
>  int qemu_devtree_nop_node(void *fdt, const char *node_path)
>  {
>      int r;
> diff --git a/device_tree.h b/device_tree.h
> index 5464dc7..f37a4da 100644
> --- a/device_tree.h
> +++ b/device_tree.h
> @@ -35,6 +35,7 @@ int qemu_devtree_setprop_string(void *fdt, const char 
> *node_path,
>  int qemu_devtree_setprop_phandle(void *fdt, const char *node_path,
>                                   const char *property, const char *string);
>  uint32_t qemu_devtree_get_phandle(void *fdt, const char *path);
> +uint32_t qemu_devtree_alloc_phandle(void *fdt);
>  int qemu_devtree_nop_node(void *fdt, const char *node_path);
>  int qemu_devtree_add_subnode(void *fdt, const char *name);
>