[U-Boot] [PATCH] libfdt: introduce function fdt_get_max_phandle

[U-Boot] [PATCH] libfdt: introduce function fdt_get_max_phandle

[Timur Tabi]

Introduce function fdt_get_max_phandle(), which returns the largest value
of all phandles in a device tree.  This is useful for allocating a new phandle
property, since all phandles must be unique.

Signed-off-by: Timur Tabi <timur@freescale.com>
---
 include/libfdt.h    |   20 ++++++++++++++++++++
 lib/libfdt/fdt_ro.c |   17 +++++++++++++++++
 2 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/include/libfdt.h b/include/libfdt.h
index d23d40e..62c4e5b 100644
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -833,6 +833,26 @@ int fdt_nop_property(void *fdt, int nodeoffset, const char *name);
  */
 int fdt_nop_node(void *fdt, int nodeoffset);
 
+/**
+ * fdt_get_max_phandle - return the largest value of all phandles in the fdt
+ * @fdt: pointer to the device tree blob
+ *
+ * fdt_get_max_phandle() returns the largest value of all phandles.
+ *
+ * phandles are generally numbered sequentially from 1.  To allow U-Boot to
+ * create a new phandle property, the value of that phandle must be unique.
+ * The safest way to do that is to determine the largest value among all
+ * phandles, and set the new phandle to that value plus one.
+ *
+ * returns:
+ *	0, there are no phandles in the fdt
+ *	>0, the largest value of the phandles
+ *	-FDT_ERR_BADMAGIC,
+ *	-FDT_ERR_BADVERSION,
+ *	-FDT_ERR_BADSTATE, standard meanings
+ */
+int fdt_get_max_phandle(const void *fdt);
+
 /**********************************************************************/
 /* Sequential write functions                                         */
 /**********************************************************************/
diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 1e1e322..4a4a84b 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -504,3 +504,20 @@ int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
 
 	return offset; /* error from fdt_next_node() */
 }
+
+int fdt_get_max_phandle(const void *fdt)
+{
+	int offset;
+	uint32_t temp, phandle = 0;
+
+	FDT_CHECK_HEADER(fdt);
+
+	for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0;
+	     offset = fdt_next_node(fdt, offset, NULL)) {
+		temp = fdt_get_phandle(fdt, offset);
+		if (temp > phandle)
+			phandle = temp;
+	}
+
+	return phandle;
+}
-- 
1.6.5

[U-Boot] [PATCH] libfdt: introduce function fdt_get_max_phandle

[Wolfgang Denk]

Dear Timur Tabi,

In message <1274308618-2974-1-git-send-email-timur@freescale.com> you wrote:
> Introduce function fdt_get_max_phandle(), which returns the largest value
> of all phandles in a device tree.  This is useful for allocating a new phandle
> property, since all phandles must be unique.
> 
> Signed-off-by: Timur Tabi <timur@freescale.com>
> ---
>  include/libfdt.h    |   20 ++++++++++++++++++++
>  lib/libfdt/fdt_ro.c |   17 +++++++++++++++++
>  2 files changed, 37 insertions(+), 0 deletions(-)

Please submit as part of a patch / patch series that acrtually uses
this feature.  As is, it's just dead code that has no users.

> +int fdt_get_max_phandle(const void *fdt)
> +{
> +	int offset;
> +	uint32_t temp, phandle = 0;
> +
> +	FDT_CHECK_HEADER(fdt);
> +
> +	for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0;
> +	     offset = fdt_next_node(fdt, offset, NULL)) {
> +		temp = fdt_get_phandle(fdt, offset);
> +		if (temp > phandle)
> +			phandle = temp;
> +	}
> +
> +	return phandle;
> +}

As fdt_get_phandle() returns a uint32_t, fdt_get_max_phandle() should
return the same type, not int.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Star Trek Lives!

[U-Boot] [PATCH] libfdt: introduce function fdt_get_max_phandle

[Jerry Van Baren]

Wolfgang Denk wrote:
> Dear Timur Tabi,
> 
> In message <1274308618-2974-1-git-send-email-timur@freescale.com> you wrote:
>> Introduce function fdt_get_max_phandle(), which returns the largest value
>> of all phandles in a device tree.  This is useful for allocating a new phandle
>> property, since all phandles must be unique.
>>
>> Signed-off-by: Timur Tabi <timur@freescale.com>
>> ---
>>  include/libfdt.h    |   20 ++++++++++++++++++++
>>  lib/libfdt/fdt_ro.c |   17 +++++++++++++++++
>>  2 files changed, 37 insertions(+), 0 deletions(-)
> 
> Please submit as part of a patch / patch series that acrtually uses
> this feature.  As is, it's just dead code that has no users.

I'm happy with this in principle, and will <ack> formally when the 
community is OK with the code change.  It looks like a positive 
improvement to me, reducing complexity and addressing Timur/Freescale's 
needs.  Anyway, I envision <acking> the patch and having FSL include it 
in whatever MPC8xxx patchset that actually needs the changes.

Thanks and best regards,
gvb

[snip improvement suggestion]

[U-Boot] [PATCH] libfdt: introduce function fdt_get_max_phandle

[Kumar Gala]

On May 26, 2010, at 9:38 PM, Jerry Van Baren wrote:

> Wolfgang Denk wrote:
>> Dear Timur Tabi,
>> 
>> In message <1274308618-2974-1-git-send-email-timur@freescale.com> you wrote:
>>> Introduce function fdt_get_max_phandle(), which returns the largest value
>>> of all phandles in a device tree.  This is useful for allocating a new phandle
>>> property, since all phandles must be unique.
>>> 
>>> Signed-off-by: Timur Tabi <timur@freescale.com>
>>> ---
>>> include/libfdt.h    |   20 ++++++++++++++++++++
>>> lib/libfdt/fdt_ro.c |   17 +++++++++++++++++
>>> 2 files changed, 37 insertions(+), 0 deletions(-)
>> 
>> Please submit as part of a patch / patch series that acrtually uses
>> this feature.  As is, it's just dead code that has no users.
> 
> I'm happy with this in principle, and will <ack> formally when the 
> community is OK with the code change.  It looks like a positive 
> improvement to me, reducing complexity and addressing Timur/Freescale's 
> needs.  Anyway, I envision <acking> the patch and having FSL include it 
> in whatever MPC8xxx patchset that actually needs the changes.
> 
> Thanks and best regards,
> gvb

We should NOT add code to libfdt if we can avoid it.  We should be doing this in fdt_support.c.  libfdt changes should first go to dtc.

- k