linux-kernel - Re: [RFC PATCH 1/3] clk: add clk_bulk

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Message-ID: <20170422031647.GW7065@codeaurora.org>
Date:   Fri, 21 Apr 2017 20:16:47 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Dong Aisheng <aisheng.dong@....com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de,
        broonie@...nel.org, yibin.gong@....com, rjw@...ysocki.net,
        viresh.kumar@...aro.org, mturquette@...libre.com,
        shawnguo@...nel.org, fabio.estevam@....com, anson.huang@....com,
        ping.bai@....com, leonard.crestez@....com, octavian.purdila@....com
Subject: Re: [RFC PATCH 1/3] clk: add clk_bulk_get accessories

On 04/12, Dong Aisheng wrote:
>  
>  #ifdef CONFIG_HAVE_CLK
> @@ -230,6 +257,32 @@ static inline void clk_unprepare(struct clk *clk)
>  struct clk *clk_get(struct device *dev, const char *id);
>  
>  /**
> + * clk_bulk_get - lookup and obtain a number of references to clock producer.
> + * @dev: device for clock "consumer"
> + * @num_clks: the number of clk_bulk_data
> + * @clks: the clk_bulk_data table of consumer
> + *
> + * This helper function allows drivers to get several clk consumers in one
> + * operation. If any of the clk cannot be acquired then any clks
> + * that were obtained will be freed before returning to the caller.
> + *
> + * Returns 0 if all clocks specified in clk_bulk_data table are obtained
> + * successfully, or valid IS_ERR() condition containing errno.
> + * The implementation uses @dev and @clk_bulk_data.id to determine the
> + * clock consumer, and thereby the clock producer.
> + * (IOW, @id may be identical strings, but clk_get may return different
> + * clock producers depending on @dev.) The clock returned is stored in

This comment is inaccurate. Only one dev is possible with this
API.

> + * each @clk_bulk_data.clk field.
> + *
> + * Drivers must assume that the clock source is not enabled.
> + *
> + * clk_bulk_get should not be called from within interrupt context.
> + */
> +

Drop space.

> +int __must_check clk_bulk_get(struct device *dev, int num_clks,
> +			      struct clk_bulk_data *clks);
> +
> +/**
>   * devm_clk_get - lookup and obtain a managed reference to a clock producer.
>   * @dev: device for clock "consumer"
>   * @id: clock consumer ID
> @@ -279,6 +332,20 @@ struct clk *devm_get_clk_from_child(struct device *dev,
>  int clk_enable(struct clk *clk);
>  
>  /**
> + * clk_bulk_enable - inform the system when the bulk of clock source should
> + *		     be running.
> + * @num_clks: the number of clk_bulk_data
> + * @clks: the clk_bulk_data table of consumer
> + *
> + * If the clock can not be enabled/disabled all, this should return success.
> + *
> + * May be called from atomic contexts.
> + *
> + * Returns success (0) or negative errno.
> + */
> +int __must_check clk_bulk_enable(int num_clks, struct clk_bulk_data *clks);
> +
> +/**
>   * clk_disable - inform the system when the clock source is no longer required.
>   * @clk: clock source
>   *
> @@ -295,6 +362,24 @@ int clk_enable(struct clk *clk);
>  void clk_disable(struct clk *clk);
>  
>  /**
> + * clk_bulk_disable - inform the system when the bulk of clock source is no
> + *		      longer required.
> + * @num_clks: the number of clk_bulk_data
> + * @clks: the clk_bulk_data table of consumer
> + *
> + * Inform the system that a bulk of clock source is no longer required by
> + * a driver and may be shut down.
> + *
> + * May be called from atomic contexts.
> + *
> + * Implementation detail: if the bulk of clock source is shared between

I'm not sure "bulk of clock source" is the correct terminology.
Perhaps "set of clks"?

> + * multiple drivers, clk_bulk_enable() calls must be balanced by the
> + * same number of clk_bulk_disable() calls for the clock source to be
> + * disabled.
> + */
> +void clk_bulk_disable(int num_clks, struct clk_bulk_data *clks);

We can mark clk_bulk_data structure as const here? Probably
applies in other places as well in this patch.

-- 
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