[PATCH v4 4/7] rtc: ac100: Add clk output support

[Michael Turquette]

Quoting Chen-Yu Tsai (2016-07-13 20:34:34)
> On Sat, Jul 9, 2016 at 2:36 AM, Michael Turquette
> <mturquette at baylibre.com> wrote:
> > Quoting Chen-Yu Tsai (2016-06-30 08:58:48)
> >> +static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
> >> +                                   unsigned long prate)
> >> +{
> >> +       unsigned long best_rate = 0, tmp_rate, tmp_prate;
> >> +       int i;
> >> +
> >> +       if (prate == AC100_RTC_32K_RATE)
> >> +               return divider_round_rate(hw, rate, &prate, NULL,
> >> +                                         AC100_CLKOUT_DIV_WIDTH,
> >> +                                         CLK_DIVIDER_POWER_OF_TWO);
> >> +
> >> +       for (i = 0; ac100_clkout_prediv[i].div; i++) {
> >> +               tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
> >> +               tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
> >> +                                             AC100_CLKOUT_DIV_WIDTH,
> >> +                                             CLK_DIVIDER_POWER_OF_TWO);
> >> +
> >> +               if (tmp_rate > rate)
> >> +                       continue;
> >> +               if (rate - tmp_rate < best_rate - tmp_rate)
> >> +                       best_rate = tmp_rate;
> >> +       }
> >> +
> >> +       return best_rate;
> >> +}
> >> +
> >> +static int ac100_clkout_determine_rate(struct clk_hw *hw,
> >> +                                      struct clk_rate_request *req)
> >> +{
> >> +       struct clk_hw *best_parent;
> >> +       unsigned long best = 0;
> >> +       int i, num_parents = clk_hw_get_num_parents(hw);
> >> +
> >> +       for (i = 0; i < num_parents; i++) {
> >> +               struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
> >> +               unsigned long tmp, prate = clk_hw_get_rate(parent);
> >> +
> >> +               tmp = ac100_clkout_round_rate(hw, req->rate, prate);
> >> +
> >> +               if (tmp > req->rate)
> >> +                       continue;
> >> +               if (req->rate - tmp < req->rate - best) {
> >> +                       best = tmp;
> >> +                       best_parent = parent;
> >> +               }
> >> +       }
> >> +
> >> +       if (!best)
> >> +               return -EINVAL;
> >> +
> >> +       req->best_parent_hw = best_parent;
> >> +       req->best_parent_rate = best;
> >> +       req->rate = best;
> >> +
> >> +       return 0;
> >> +}
> >
> > You only need one of the two functions above. Keep the .determine_rate
> > callback and drop .round_rate.
> 
> Only .round_rate is set in the clk_ops. ac100_clkout_round_rate just
> serves to split out some of the calculations done per parent.

If you only use .round_rate, shouldn't you drop .determine_rate then?

Regards,
Mike

> 
> > Otherwise the rest of the clk support looks great to me. Feel free to
> > add:
> >
> > Reviewed-by: Michael Turquette <mturquette at baylibre.com>
> 
> Thanks!
> 
> ChenYu