On Tue, Aug 07, 2012 at 20:49:48, Rob Herring wrote:
> On 08/07/2012 08:37 AM, Vaibhav Hiremath wrote:
> > If the module requires only one clocksource to function, then
> > driver can very well call clk_get() api with "con_id = NULL",
> >
> > clk = clk_get(dev, NULL);
> >
> > And platform code should respect this and return valid clk handle.
> > That means, now the clk_get() api would rely on dev_id, and platform
> > code should either have clk node with matching dev_id (with con_id=NULL)
> > or return dummy clk node.
> >
> > With DT support, we can fix the dev_id for particular module
> > using "struct of_dev_auxdata" to satisfy above clk framework requirement.
> >
> > In case of AM33XX, we required this for the DCAN module, so this
> > patch adds "of_dev_auxdata" for both DCAN_0/1 instances.
> >
> > Signed-off-by: Vaibhav Hiremath <hvaibhav@xxxxxx>
> > Cc: Tony Lindgren <tony@xxxxxxxxxxx>
> > Cc: Paul Walmsley <paul@xxxxxxxxx>
> > Cc: Benoit Cousson <b-cousson@xxxxxx>
> > Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
> > ---
> > This patch is boot tested on BeagleBone platform, and checked for
> > clk_get() return value in d_can module driver.
> >
> > arch/arm/mach-omap2/board-generic.c | 18 +++++++++++++++++-
> > 1 files changed, 17 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> > index 6f93a20..c9b7903 100644
> > --- a/arch/arm/mach-omap2/board-generic.c
> > +++ b/arch/arm/mach-omap2/board-generic.c
> > @@ -37,11 +37,27 @@ static struct of_device_id omap_dt_match_table[] __initdata = {
> > { }
> > };
> >
> > +/*
> > + * Lookup table for attaching a specific name and platform_data pointer to
> > + * devices as they get created by of_platform_populate(). Ideally this table
> > + * would not exist, but the current clock implementation depends on some devices
> > + * having a specific name OR to satisfy NULL con_id requirement from driver.
> > + */
> > +static const struct of_dev_auxdata am33xx_auxdata_lookup[] __initconst = {
> > + OF_DEV_AUXDATA("bosch,d_can", 0x481cc000, "d_can.0", NULL),
> > + OF_DEV_AUXDATA("bosch,d_can", 0x481d0000, "d_can.1", NULL),
> > + { },
> > +};
>
> Adding an additional clkdev lookup accomplishes the same thing and is a
> cleaner solution.
>
That is also required and I have submitted patch for the same -
http://www.spinics.net/lists/arm-kernel/msg187998.html
With DT support, I am getting dev_id as -
- Without "reg" property: d_can.16 and d_can.17,
(I believe it changes dynamically here)
- With "reg" property: 481cc000.d_can and 481d0000.d_can
Which is not so intuitive, I would like to see them as per Spec/TRM, so
doesn't this patch make sense?
Similar thing has already been done for other platforms too.
Thanks,
Vaibhav
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