On Sat, 23 Jan 2016, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> Sometimes it needs to check if there is a node in FDT by full path.
> Introduce this helper to get the specified name subnode if it exists.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
> CC: Rob Herring <robh@xxxxxxxxxx>
> ---
> drivers/of/fdt.c | 35 +++++++++++++++++++++++++++++++++++
> include/linux/of_fdt.h | 2 ++
> 2 files changed, 37 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 655f79d..112ec16 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -645,6 +645,41 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
> }
>
> /**
> + * of_get_flat_dt_subnode_by_name - get subnode of specified node by name
> + *
> + * @node: the parent node
> + * @uname: the name of subnode
> + * @return offset of the subnode, or -FDT_ERR_NOTFOUND if there is none
> + */
> +
> +int of_get_flat_dt_subnode_by_name(unsigned long node, const char *uname)
> +{
> + const void *blob = initial_boot_params;
> + int offset;
> + const char *pathp;
> +
> + /* Find first subnode if it exists */
> + offset = fdt_first_subnode(blob, node);
> + if (offset < 0)
> + return -FDT_ERR_NOTFOUND;
> + pathp = fdt_get_name(blob, offset, NULL);
> + if (strncmp(pathp, uname, strlen(uname)) == 0)
> + return offset;
Wouldn't this check succeed even if uname is "uefi" and the node
name is actually "uefiiiii"? You might have to use strcmp.
> + /* Find other subnodes */
> + do {
> + offset = fdt_next_subnode(blob, offset);
> + if (offset < 0)
> + return -FDT_ERR_NOTFOUND;
> + pathp = fdt_get_name(blob, offset, NULL);
> + if (strncmp(pathp, uname, strlen(uname)) == 0)
> + return offset;
> + } while (offset >= 0);
Rather than writing the name check twice, I think it would be best to
code this loop as:
for (offset = fdt_first_subnode(blob, offset);
offset >= 0;
offset = fdt_next_subnode(blob, offset)) {
/* do name check */
> + return -FDT_ERR_NOTFOUND;
> +}
> +
> +/**
> * of_get_flat_dt_root - find the root node in the flat blob
> */
> unsigned long __init of_get_flat_dt_root(void)
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index df9ef38..fc28162 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -52,6 +52,8 @@ extern char __dtb_end[];
> extern int of_scan_flat_dt(int (*it)(unsigned long node, const char *uname,
> int depth, void *data),
> void *data);
> +extern int of_get_flat_dt_subnode_by_name(unsigned long node,
> + const char *uname);
> extern const void *of_get_flat_dt_prop(unsigned long node, const char *name,
> int *size);
> extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
> --
> 2.0.4
>
>
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