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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-04-29 at 16:40 +0100, Julien Grall wrote:
> 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.

We can't use dt_compat_cmp in the early code?

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



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