linux-kernel - Re: [PATCH 2/3] clk: ux500: Support prcmu ape opp voltage clock

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Message-ID: <20120924153514.12878.47739@nucleus>
Date:	Mon, 24 Sep 2012 08:35:14 -0700
From:	Mike Turquette <mturquette@...com>
To:	Ulf Hansson <ulf.hansson@...ricsson.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Lee Jones <lee.jones@...aro.org>,
	Philippe Begnic <philippe.begnic@...com>,
	Srinidhi Kasagar <srinidhi.kasagar@...ricsson.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 2/3] clk: ux500: Support prcmu ape opp voltage clock

Quoting Ulf Hansson (2012-09-24 07:43:18)
> From: Ulf Hansson <ulf.hansson@...aro.org>
> 
> Some scalable prcmu clocks needs to be handled in conjuction with the
> ape opp 100 voltage. A new prcmu clock type clk_prcmu_opp_volt_scalable
> is implemented to handle this.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> ---
>  drivers/clk/ux500/clk-prcmu.c |   55 +++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/ux500/clk.h       |    6 +++++
>  2 files changed, 61 insertions(+)
> 
> diff --git a/drivers/clk/ux500/clk-prcmu.c b/drivers/clk/ux500/clk-prcmu.c
> index 930cdfe..04577ca 100644
> --- a/drivers/clk/ux500/clk-prcmu.c
> +++ b/drivers/clk/ux500/clk-prcmu.c
> @@ -133,6 +133,40 @@ out_error:
>                 hw->init->name);
>  }
>  
> +static int clk_prcmu_opp_volt_prepare(struct clk_hw *hw)
> +{
> +       int err;
> +       struct clk_prcmu *clk = to_clk_prcmu(hw);
> +
> +       err = prcmu_request_ape_opp_100_voltage(true);
> +       if (err) {
> +               pr_err("clk_prcmu: %s failed to request APE OPP VOLT for %s.\n",
> +                       __func__, hw->init->name);
> +               return err;
> +       }
> +
> +       err = prcmu_request_clock(clk->cg_sel, true);
> +       if (err)
> +               prcmu_request_ape_opp_100_voltage(false);
> +
> +       return err;
> +}
> +
> +static void clk_prcmu_opp_volt_unprepare(struct clk_hw *hw)
> +{
> +       struct clk_prcmu *clk = to_clk_prcmu(hw);
> +
> +       if (prcmu_request_clock(clk->cg_sel, false))
> +               goto out_error;
> +       if (prcmu_request_ape_opp_100_voltage(false))
> +               goto out_error;
> +       return;
> +
> +out_error:
> +       pr_err("clk_prcmu: %s failed to disable %s.\n", __func__,
> +               hw->init->name);
> +}

Hello Ulf,

I was hoping to use the rate-change notifiers for voltage scaling, as in
my clk reentrancy/dvfs RFCs.  Using prepare/unprepare to set voltage for
non-scalable clocks is probably OK; do you plan to scale voltage when
your clocks change rate?  If so then you will need more than just
prepare/unprepare.

Regards,
Mike

> +
>  static struct clk_ops clk_prcmu_scalable_ops = {
>         .prepare = clk_prcmu_prepare,
>         .unprepare = clk_prcmu_unprepare,
> @@ -167,6 +201,17 @@ static struct clk_ops clk_prcmu_opp_gate_ops = {
>         .recalc_rate = clk_prcmu_recalc_rate,
>  };
>  
> +static struct clk_ops clk_prcmu_opp_volt_scalable_ops = {
> +       .prepare = clk_prcmu_opp_volt_prepare,
> +       .unprepare = clk_prcmu_opp_volt_unprepare,
> +       .enable = clk_prcmu_enable,
> +       .disable = clk_prcmu_disable,
> +       .is_enabled = clk_prcmu_is_enabled,
> +       .recalc_rate = clk_prcmu_recalc_rate,
> +       .round_rate = clk_prcmu_round_rate,
> +       .set_rate = clk_prcmu_set_rate,
> +};
> +
>  static struct clk *clk_reg_prcmu(const char *name,
>                                  const char *parent_name,
>                                  u8 cg_sel,
> @@ -250,3 +295,13 @@ struct clk *clk_reg_prcmu_opp_gate(const char *name,
>         return clk_reg_prcmu(name, parent_name, cg_sel, 0, flags,
>                         &clk_prcmu_opp_gate_ops);
>  }
> +
> +struct clk *clk_reg_prcmu_opp_volt_scalable(const char *name,
> +                                           const char *parent_name,
> +                                           u8 cg_sel,
> +                                           unsigned long rate,
> +                                           unsigned long flags)
> +{
> +       return clk_reg_prcmu(name, parent_name, cg_sel, rate, flags,
> +                       &clk_prcmu_opp_volt_scalable_ops);
> +}
> diff --git a/drivers/clk/ux500/clk.h b/drivers/clk/ux500/clk.h
> index 836d7d1..f36eeed 100644
> --- a/drivers/clk/ux500/clk.h
> +++ b/drivers/clk/ux500/clk.h
> @@ -45,4 +45,10 @@ struct clk *clk_reg_prcmu_opp_gate(const char *name,
>                                    u8 cg_sel,
>                                    unsigned long flags);
>  
> +struct clk *clk_reg_prcmu_opp_volt_scalable(const char *name,
> +                                           const char *parent_name,
> +                                           u8 cg_sel,
> +                                           unsigned long rate,
> +                                           unsigned long flags);
> +
>  #endif /* __UX500_CLK_H */
> -- 
> 1.7.10
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