linux-kernel - Re: [PATCH v3 1/2] clk: Provide managed helper to get and enable bulk clocks

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Message-ID: <20240120150303.GB5405@thinkpad>
Date: Sat, 20 Jan 2024 20:33:03 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Shradha Todi <shradha.t@...sung.com>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, mturquette@...libre.com,
	sboyd@...nel.org, jingoohan1@...il.com, lpieralisi@...nel.org,
	kw@...ux.com, robh@...nel.org, bhelgaas@...gle.com,
	krzysztof.kozlowski@...aro.org, alim.akhtar@...sung.com,
	linux@...linux.org.uk, m.szyprowski@...sung.com
Subject: Re: [PATCH v3 1/2] clk: Provide managed helper to get and enable
 bulk clocks

On Wed, Jan 10, 2024 at 04:31:14PM +0530, Shradha Todi wrote:
> Provide a managed devm_clk_bulk* wrapper to get and enable all
> bulk clocks in order to simplify drivers that keeps all clocks
> enabled for the time of driver operation.
> 
> Suggested-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Shradha Todi <shradha.t@...sung.com>
> ---
>  drivers/clk/clk-devres.c | 41 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/clk.h      | 25 ++++++++++++++++++++++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
> index 4fb4fd4b06bd..05b0ff4bc1d4 100644
> --- a/drivers/clk/clk-devres.c
> +++ b/drivers/clk/clk-devres.c
> @@ -102,6 +102,7 @@ EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled);
>  struct clk_bulk_devres {
>  	struct clk_bulk_data *clks;
>  	int num_clks;
> +	void (*exit)(int num_clks, const struct clk_bulk_data *clks);
>  };
>  
>  static void devm_clk_bulk_release(struct device *dev, void *res)
> @@ -182,6 +183,46 @@ int __must_check devm_clk_bulk_get_all(struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all);
>  
> +static void devm_clk_bulk_release_all_enabled(struct device *dev, void *res)
> +{
> +	struct clk_bulk_devres *devres = res;
> +
> +	if (devres->exit)
> +		devres->exit(devres->num_clks, devres->clks);
> +
> +	clk_bulk_put_all(devres->num_clks, devres->clks);
> +}
> +
> +int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
> +				  struct clk_bulk_data **clks, int *num_clks)

What is the user supposed to do with "num_clks" when you are already handling
the enable part?

> +{
> +	struct clk_bulk_devres *devres;
> +	int ret;
> +
> +	devres = devres_alloc(devm_clk_bulk_release_all_enabled,
> +			      sizeof(*devres), GFP_KERNEL);
> +	if (!devres)
> +		return -ENOMEM;
> +
> +	ret = clk_bulk_get_all(dev, &devres->clks);
> +	if (ret > 0) {
> +		*clks = devres->clks;
> +		devres->num_clks = ret;
> +		*num_clks = ret;
> +		devres_add(dev, devres);

If you move the statements inside this condition to the end of this function,
you could get rid of the exit() callback and directly use
clk_bulk_disable_unprepare() in devm_clk_bulk_release_all_enabled().

> +	} else {
> +		devres_free(devres);
> +		return ret;
> +	}
> +
> +	ret = clk_bulk_prepare_enable(devres->num_clks, *clks);
> +	if (!ret)
> +		devres->exit = clk_bulk_disable_unprepare;

Here you can just do clk_bulk_put_all() and devres_free() directly because you
know that the driver won't proceed after this error.

- Mani

> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all_enabled);
> +
>  static int devm_clk_match(struct device *dev, void *res, void *data)
>  {
>  	struct clk **c = res;
> diff --git a/include/linux/clk.h b/include/linux/clk.h
> index 1ef013324237..bf3e9bee5754 100644
> --- a/include/linux/clk.h
> +++ b/include/linux/clk.h
> @@ -438,6 +438,24 @@ int __must_check devm_clk_bulk_get_optional(struct device *dev, int num_clks,
>  int __must_check devm_clk_bulk_get_all(struct device *dev,
>  				       struct clk_bulk_data **clks);
>  
> +/**
> + * devm_clk_bulk_get_all_enabled - managed get multiple clk consumers and
> + *					enable all clk
> + * @dev: device for clock "consumer"
> + * @clks: pointer to the clk_bulk_data table of consumer
> + * @num_clks: out parameter to store the number of clk_bulk_data
> + *
> + * Returns success (0) or negative errno.
> + *
> + * This helper function allows drivers to get several clk
> + * consumers and enable all of them in one operation with management.
> + * The clks will automatically be disabled and freed when the device
> + * is unbound.
> + */
> +
> +int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
> +				struct clk_bulk_data **clks, int *num_clks);
> +
>  /**
>   * devm_clk_get - lookup and obtain a managed reference to a clock producer.
>   * @dev: device for clock "consumer"
> @@ -960,6 +978,13 @@ static inline int __must_check devm_clk_bulk_get_all(struct device *dev,
>  	return 0;
>  }
>  
> +static inline int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
> +				struct clk_bulk_data **clks, int *num_clks)
> +{
> +
> +	return 0;
> +}
> +
>  static inline struct clk *devm_get_clk_from_child(struct device *dev,
>  				struct device_node *np, const char *con_id)
>  {
> -- 
> 2.17.1
> 

-- 
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