Re: [Qemu-devel] [PATCH v2 3/7] device_tree: introduce qemu_fdt_node_path

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Jan 06, 2016 at 03:13:21PM +0000, Eric Auger wrote:
> This new helper routine returns the node path of a device
> referred to by its node name and compat string.

What if there are multiple nodes matching the name and compat?

> 
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> 
> ---
> 
> v1 -> v2:
> - move doc comment in header file
> - do not use a fixed size buffer
> - break on errors in while loop
> - use strcmp instead of strncmp
> 
> RFC -> v1:
> - improve error handling according to Alex' comments
> ---
>  device_tree.c                | 37 +++++++++++++++++++++++++++++++++++++
>  include/sysemu/device_tree.h | 14 ++++++++++++++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/device_tree.c b/device_tree.c
> index b262c2d..8441e01 100644
> --- a/device_tree.c
> +++ b/device_tree.c
> @@ -231,6 +231,43 @@ static int findnode_nofail(void *fdt, const char *node_path)
>      return offset;
>  }
>  
> +int qemu_fdt_node_path(void *fdt, const char *name, char *compat,
> +                       char **node_path)
> +{
> +    int offset, len, ret;
> +    const char *iter_name;
> +    unsigned int path_len = 16;
> +    char *path;
> +
> +    *node_path = NULL;
> +    offset = fdt_node_offset_by_compatible(fdt, -1, compat);
> +
> +    while (offset >= 0) {
> +        iter_name = fdt_get_name(fdt, offset, &len);
> +        if (!iter_name) {
> +            offset = len;
> +            break;
> +        }
> +        if (!strcmp(iter_name, name)) {
> +            goto found;
> +        }
> +        offset = fdt_node_offset_by_compatible(fdt, offset, compat);
> +    }
> +    return offset;
> +
> +found:
> +    path = g_malloc(path_len);
> +    while ((ret = fdt_get_path(fdt, offset, path, path_len))
> +            == -FDT_ERR_NOSPACE) {
> +        path_len += 16;
> +        path = g_realloc(path, path_len);
> +    }
> +    if (!ret) {
> +        *node_path = path;
> +    }
> +    return ret;
> +}
> +
>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>                       const char *property, const void *val, int size)
>  {
> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
> index fdf25a4..269cb1c 100644
> --- a/include/sysemu/device_tree.h
> +++ b/include/sysemu/device_tree.h
> @@ -20,6 +20,20 @@ void *load_device_tree(const char *filename_path, int *sizep);
>  void *load_device_tree_from_sysfs(void);
>  #endif
>  
> +/**
> + * qemu_fdt_node_path: return the node path of a device, given its
> + * node name and its compat string
> + * @fdt: pointer to the dt blob
> + * @name: device node name
> + * @compat: compatibility string of the device
> + * @node_path: returned node path
> + *
> + * upon success, the path is output at node_path address
> + * returns 0 on success, < 0 on failure
> + */
> +int qemu_fdt_node_path(void *fdt, const char *name, char *compat,
> +                       char **node_path);
> +
>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>                       const char *property, const void *val, int size);
>  int qemu_fdt_setprop_cell(void *fdt, const char *node_path,

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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