Re: [Xen-devel] [RFC 08/29] xen/arm: Add helpers to use the device tree

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 04/29/2013 04:23 PM, Ian Campbell wrote:

> On Mon, 2013-04-29 at 00:01 +0100, Julien Grall wrote:
> 
> Are these also from Linux?
> 
>> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
>> ---
>>  xen/common/device_tree.c      |  120 
>> +++++++++++++++++++++++++++++++++++++++++
>>  xen/include/xen/device_tree.h |  120 
>> +++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 240 insertions(+)
>>
>> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
>> index 05285b7..dd4b813 100644
>> --- a/xen/common/device_tree.c
>> +++ b/xen/common/device_tree.c
>> @@ -573,6 +573,54 @@ const void *dt_get_property(const struct dt_device_node 
>> *np,
>>      return pp ? pp->value : NULL;
>>  }
>>  
>> +bool_t dt_device_is_compatible(const struct dt_device_node *device,
>> +                               const char *compat)
>> +{
>> +    const char* cp;
>> +    u32 cplen, l;
>> +
>> +    cp = dt_get_property(device, "compatible", &cplen);
>> +    if ( cp == NULL )
>> +        return 0;
>> +    while ( cplen > 0 )
>> +    {
>> +        if ( dt_compat_cmp(cp, compat, strlen(compat)) == 0 )
> 
> We have functions which do this already, don't we? Also things like
> dt_node_cmp, dt_read_number etc have analogues in the current code.
> 
> If these are from Linux I'm inclined to believe they will be better than
> our own. For 4.4 we should look at removing our variants.
> 
> Or maybe if I keep reading the series I will find them going away
> already?


In fact it's exactly the same, except the current function deals with
flat device tree and the new one deals with the hierarchical device tree.

I'm afraid we can't remove this duplicate code, we still need it for
early scan of the device tree to retrieve memory, cpus, and modules
informations.

Once all the xen code moved to the new device tree API. This function
will be static.

-- 
Julien Grall

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