| Message ID | 1401209816-24953-1-git-send-email-elder@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Quoting Alex Elder (2014-05-27 09:56:56) > Implement the clk->determine_rate method for Broadcom Kona peripheral > clocks. This allows a peripheral clock to be re-parented in order to > satisfy a rate change request. This takes the place of the previous > kona_peri_clk_round_rate() functionality, though that function remains > because it is used by the new one. > > The parent clock that allows the peripheral clock to produce a rate > closest to the one requested is the one selected, though the current > parent is used by default. > > Signed-off-by: Alex Elder <elder@linaro.org> Applied to clk-next. Regards, Mike > --- > v2: Added WARN_ON_ONCE() call as suggested. > > This patch is based on Mike Turquette's current "clk-next" branch. > 42dd880 Merge branch 'clk-fixes' into clk-next > > It is available here: > http://git.linaro.org/landing-teams/working/broadcom/kernel.git > Branch review/bcm-determine-rate-v2 > > drivers/clk/bcm/clk-kona.c | 54 +++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 53 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c > index d603c4e..95af2e6 100644 > --- a/drivers/clk/bcm/clk-kona.c > +++ b/drivers/clk/bcm/clk-kona.c > @@ -1031,6 +1031,58 @@ static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate, > rate ? rate : 1, *parent_rate, NULL); > } > > +static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate, > + unsigned long *best_parent_rate, struct clk **best_parent) > +{ > + struct kona_clk *bcm_clk = to_kona_clk(hw); > + struct clk *clk = hw->clk; > + struct clk *current_parent; > + unsigned long parent_rate; > + unsigned long best_delta; > + unsigned long best_rate; > + u32 parent_count; > + u32 which; > + > + /* > + * If there is no other parent to choose, use the current one. > + * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT. > + */ > + WARN_ON_ONCE(bcm_clk->init_data.flags & CLK_SET_RATE_NO_REPARENT); > + parent_count = (u32)bcm_clk->init_data.num_parents; > + if (parent_count < 2) > + return kona_peri_clk_round_rate(hw, rate, best_parent_rate); > + > + /* Unless we can do better, stick with current parent */ > + current_parent = clk_get_parent(clk); > + parent_rate = __clk_get_rate(current_parent); > + best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); > + best_delta = abs(best_rate - rate); > + > + /* Check whether any other parent clock can produce a better result */ > + for (which = 0; which < parent_count; which++) { > + struct clk *parent = clk_get_parent_by_index(clk, which); > + unsigned long delta; > + unsigned long other_rate; > + > + BUG_ON(!parent); > + if (parent == current_parent) > + continue; > + > + /* We don't support CLK_SET_RATE_PARENT */ > + parent_rate = __clk_get_rate(parent); > + other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); > + delta = abs(other_rate - rate); > + if (delta < best_delta) { > + best_delta = delta; > + best_rate = other_rate; > + *best_parent = parent; > + *best_parent_rate = parent_rate; > + } > + } > + > + return best_rate; > +} > + > static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index) > { > struct kona_clk *bcm_clk = to_kona_clk(hw); > @@ -1135,7 +1187,7 @@ struct clk_ops kona_peri_clk_ops = { > .disable = kona_peri_clk_disable, > .is_enabled = kona_peri_clk_is_enabled, > .recalc_rate = kona_peri_clk_recalc_rate, > - .round_rate = kona_peri_clk_round_rate, > + .determine_rate = kona_peri_clk_determine_rate, > .set_parent = kona_peri_clk_set_parent, > .get_parent = kona_peri_clk_get_parent, > .set_rate = kona_peri_clk_set_rate, > -- > 1.9.1 >
diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c index d603c4e..95af2e6 100644 --- a/drivers/clk/bcm/clk-kona.c +++ b/drivers/clk/bcm/clk-kona.c @@ -1031,6 +1031,58 @@ static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate, rate ? rate : 1, *parent_rate, NULL); } +static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *best_parent_rate, struct clk **best_parent) +{ + struct kona_clk *bcm_clk = to_kona_clk(hw); + struct clk *clk = hw->clk; + struct clk *current_parent; + unsigned long parent_rate; + unsigned long best_delta; + unsigned long best_rate; + u32 parent_count; + u32 which; + + /* + * If there is no other parent to choose, use the current one. + * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT. + */ + WARN_ON_ONCE(bcm_clk->init_data.flags & CLK_SET_RATE_NO_REPARENT); + parent_count = (u32)bcm_clk->init_data.num_parents; + if (parent_count < 2) + return kona_peri_clk_round_rate(hw, rate, best_parent_rate); + + /* Unless we can do better, stick with current parent */ + current_parent = clk_get_parent(clk); + parent_rate = __clk_get_rate(current_parent); + best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); + best_delta = abs(best_rate - rate); + + /* Check whether any other parent clock can produce a better result */ + for (which = 0; which < parent_count; which++) { + struct clk *parent = clk_get_parent_by_index(clk, which); + unsigned long delta; + unsigned long other_rate; + + BUG_ON(!parent); + if (parent == current_parent) + continue; + + /* We don't support CLK_SET_RATE_PARENT */ + parent_rate = __clk_get_rate(parent); + other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); + delta = abs(other_rate - rate); + if (delta < best_delta) { + best_delta = delta; + best_rate = other_rate; + *best_parent = parent; + *best_parent_rate = parent_rate; + } + } + + return best_rate; +} + static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index) { struct kona_clk *bcm_clk = to_kona_clk(hw); @@ -1135,7 +1187,7 @@ struct clk_ops kona_peri_clk_ops = { .disable = kona_peri_clk_disable, .is_enabled = kona_peri_clk_is_enabled, .recalc_rate = kona_peri_clk_recalc_rate, - .round_rate = kona_peri_clk_round_rate, + .determine_rate = kona_peri_clk_determine_rate, .set_parent = kona_peri_clk_set_parent, .get_parent = kona_peri_clk_get_parent, .set_rate = kona_peri_clk_set_rate,
Implement the clk->determine_rate method for Broadcom Kona peripheral clocks. This allows a peripheral clock to be re-parented in order to satisfy a rate change request. This takes the place of the previous kona_peri_clk_round_rate() functionality, though that function remains because it is used by the new one. The parent clock that allows the peripheral clock to produce a rate closest to the one requested is the one selected, though the current parent is used by default. Signed-off-by: Alex Elder <elder@linaro.org> --- v2: Added WARN_ON_ONCE() call as suggested. This patch is based on Mike Turquette's current "clk-next" branch. 42dd880 Merge branch 'clk-fixes' into clk-next It is available here: http://git.linaro.org/landing-teams/working/broadcom/kernel.git Branch review/bcm-determine-rate-v2 drivers/clk/bcm/clk-kona.c | 54 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-)