[v3,16/17] FDT: Add a helper to get specified name subnode
diff mbox

Message ID 1453519184-11908-17-git-send-email-zhaoshenglong@huawei.com
State New, archived
Headers show

Commit Message

Shannon Zhao Jan. 23, 2016, 3:19 a.m. UTC
From: Shannon Zhao <shannon.zhao@linaro.org>

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@linaro.org>
---
CC: Rob Herring <robh@kernel.org>
---
 drivers/of/fdt.c       | 35 +++++++++++++++++++++++++++++++++++
 include/linux/of_fdt.h |  2 ++
 2 files changed, 37 insertions(+)

Comments

Stefano Stabellini Jan. 26, 2016, 12:11 p.m. UTC | #1
On Sat, 23 Jan 2016, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
> 
> 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@linaro.org>
> ---
> CC: Rob Herring <robh@kernel.org>
> ---
>  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
> 
>
Shannon Zhao Jan. 26, 2016, 12:27 p.m. UTC | #2
On 2016/1/26 20:11, Stefano Stabellini wrote:
> On Sat, 23 Jan 2016, Shannon Zhao wrote:
>> > From: Shannon Zhao <shannon.zhao@linaro.org>
>> > 
>> > 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@linaro.org>
>> > ---
>> > CC: Rob Herring <robh@kernel.org>
>> > ---
>> >  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.
> 
Ah, yes. Will fix this.

> 
>> > +	/* 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 */
> 
> 
> 
Thanks for your suggestion. Will change this.

Patch
diff mbox

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;
+
+	/* 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);
+
+	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);