[PATCH 04/10] clk: implement parent pass through functions

[s.hauer@pengutronix.de (Sascha Hauer)]

On Mon, Apr 18, 2011 at 11:25:04AM +0200, Uwe Kleine-K?nig wrote:
> On Fri, Apr 15, 2011 at 09:08:09PM +0200, Sascha Hauer wrote:
> > A common case for clocks is that certain operations are not implemented
> > and shall be passed through to the parent. Add convenience functions
> > for this purpose
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > Cc: Jeremy Kerr <jeremy.kerr@canonical.com>
> > ---
> >  drivers/clk/clk.c   |   77 +++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/clk.h |    9 ++++++
> >  2 files changed, 86 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index 264c809..7e2c182 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -171,3 +171,80 @@ struct clk_ops clk_fixed_ops = {
> >  	.get_rate = clk_fixed_get_rate,
> >  };
> >  EXPORT_SYMBOL_GPL(clk_fixed_ops);
> > +
> > +int clk_parent_prepare(struct clk *clk)
> > +{
> > +	struct clk *parent = clk_get_parent(clk);
> > +
> > +	if (IS_ERR(parent))
> > +		return -ENOSYS;
> > +
> > +	return clk_prepare(parent);
> > +}
> > +EXPORT_SYMBOL_GPL(clk_parent_prepare);
> > +
> > +void clk_parent_unprepare(struct clk *clk)
> > +{
> > +	struct clk *parent = clk_get_parent(clk);
> > +
> > +	if (IS_ERR(parent))
> > +		return;
> > +
> > +	clk_unprepare(parent);
> > +}
> > +EXPORT_SYMBOL_GPL(clk_parent_unprepare);
> > +
> > +int clk_parent_enable(struct clk *clk)
> > +{
> > +	struct clk *parent = clk_get_parent(clk);
> > +
> > +	if (IS_ERR(parent))
> > +		return 0;
> Do you really want to return 0 here? IMHO something is fishy if a clock
> has .enable = clk_parent_enable but has no parent.

However we decide, it should return the same value as clk_parent_prepare
above. Yes, -ENOSYS seems better here.

> >  
> > +/* generic pass-through-to-parent functions */
> > +int clk_parent_prepare(struct clk *clk);
> > +void clk_parent_unprepare(struct clk *clk);
> > +int clk_parent_enable(struct clk *clk);
> > +void clk_parent_disable(struct clk *clk);
> > +unsigned long clk_parent_get_rate(struct clk *clk);
> > +long clk_parent_round_rate(struct clk *clk, unsigned long rate);
> > +int clk_parent_set_rate(struct clk *clk, unsigned long rate);
> > +
> Technically they don't need to depend on USE_COMMON_STRUCT_CLK.

Indeed. Maybe this dependency can add some motivation to switch to
common struct clk.

Sascha

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