clk: bcm/kona: implement determine_rate()

Message ID 1400592297-22171-1-git-send-email-elder@linaro.org
State New
Headers show

Commit Message

Alex Elder May 20, 2014, 1:24 p.m.
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>
---
This patch is based on Mike Turquette's current "clk-next" branch.
    6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern...

It is available here:
    http://git.linaro.org/landing-teams/working/broadcom/kernel.git
    Branch review/bcm-determine-rate

 drivers/clk/bcm/clk-kona.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

Comments

Mike Turquette May 23, 2014, 11:18 p.m. | #1
Quoting Alex Elder (2014-05-20 06:24:57)
> 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>
> ---
> This patch is based on Mike Turquette's current "clk-next" branch.
>     6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern...
> 
> It is available here:
>     http://git.linaro.org/landing-teams/working/broadcom/kernel.git
>     Branch review/bcm-determine-rate
> 
>  drivers/clk/bcm/clk-kona.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
> index d603c4e..1a4eccc 100644
> --- a/drivers/clk/bcm/clk-kona.c
> +++ b/drivers/clk/bcm/clk-kona.c
> @@ -1031,6 +1031,57 @@ 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.
> +        */

A WARN_ONCE is appropriate upon detection of CLK_SET_RATE_NO_REPARENT.
It will certainly help someone that is debugging why that flag has no
effect.

Otherwise the patch looks good to me.

Regards,
Mike

> +       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 +1186,7 @@ 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
> 
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Alex Elder May 23, 2014, 11:24 p.m. | #2
On 05/23/2014 06:18 PM, Mike Turquette wrote:
> Quoting Alex Elder (2014-05-20 06:24:57)
>> 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>
>> ---
>> This patch is based on Mike Turquette's current "clk-next" branch.
>>     6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern...
>>
>> It is available here:
>>     http://git.linaro.org/landing-teams/working/broadcom/kernel.git
>>     Branch review/bcm-determine-rate
>>
>>  drivers/clk/bcm/clk-kona.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 52 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
>> index d603c4e..1a4eccc 100644
>> --- a/drivers/clk/bcm/clk-kona.c
>> +++ b/drivers/clk/bcm/clk-kona.c
>> @@ -1031,6 +1031,57 @@ 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.
>> +        */
> 
> A WARN_ONCE is appropriate upon detection of CLK_SET_RATE_NO_REPARENT.
> It will certainly help someone that is debugging why that flag has no
> effect.

I'll add that.

> Otherwise the patch looks good to me.

Would you like me to send an updated patch as a pull request?

Thanks.

					-Alex

> Regards,
> Mike
> 
>> +       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 +1186,7 @@ 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
>>

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Mike Turquette May 24, 2014, 12:56 a.m. | #3
Quoting Alex Elder (2014-05-23 16:24:31)
> On 05/23/2014 06:18 PM, Mike Turquette wrote:
> > Quoting Alex Elder (2014-05-20 06:24:57)
> >> 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>
> >> ---
> >> This patch is based on Mike Turquette's current "clk-next" branch.
> >>     6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern...
> >>
> >> It is available here:
> >>     http://git.linaro.org/landing-teams/working/broadcom/kernel.git
> >>     Branch review/bcm-determine-rate
> >>
> >>  drivers/clk/bcm/clk-kona.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-
> >>  1 file changed, 52 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
> >> index d603c4e..1a4eccc 100644
> >> --- a/drivers/clk/bcm/clk-kona.c
> >> +++ b/drivers/clk/bcm/clk-kona.c
> >> @@ -1031,6 +1031,57 @@ 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.
> >> +        */
> > 
> > A WARN_ONCE is appropriate upon detection of CLK_SET_RATE_NO_REPARENT.
> > It will certainly help someone that is debugging why that flag has no
> > effect.
> 
> I'll add that.

Thanks!

> 
> > Otherwise the patch looks good to me.
> 
> Would you like me to send an updated patch as a pull request?

It's up to you. For a single patch I can easily pick it. If you want to
bundle it up with the other pending patches (prereq clocks, etc) then a
pull request would be nice once all that stuff gets sorted.

Regards,
Mike

> 
> Thanks.
> 
>                                         -Alex
> 
> > Regards,
> > Mike
> > 
> >> +       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 +1186,7 @@ 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
> >>
> 
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Patch

diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
index d603c4e..1a4eccc 100644
--- a/drivers/clk/bcm/clk-kona.c
+++ b/drivers/clk/bcm/clk-kona.c
@@ -1031,6 +1031,57 @@  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.
+	 */
+	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 +1186,7 @@  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,