linux-kernel - Re: [PATCH v4 18/23] ata: libahci_platform: Add function returning a clock-handle by id

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Date:   Tue, 14 Jun 2022 17:45:35 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>, Hannes Reinecke <hare@...e.de>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 18/23] ata: libahci_platform: Add function returning a
 clock-handle by id

On 6/10/22 17:17, Serge Semin wrote:
> Since all the clocks are retrieved by the method
> ahci_platform_get_resources() there is no need for the LLD (glue) drivers
> to be looking for some particular of them in the kernel clocks table
> again. Instead we suggest to add a simple method returning a
> device-specific clock with passed connection ID if it is managed to be
> found. Otherwise the function will return NULL. Thus the glue-drivers
> won't need to either manually touching the hpriv->clks array or calling
> clk_get()-friends. The AHCI platform drivers will be able to use the new
> function right after the ahci_platform_get_resources() method invocation
> and up to the device removal.
> 
> Note the method is left unused here, but will be utilized in the framework
> of the DWC AHCI SATA driver being added in the next commit.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> 
> ---
> 
> Changelog v2:
> - Fix some grammar mistakes in the method description.
> 
> Changelog v4:
> - Add a note regarding the new method usage.
> ---
>  drivers/ata/libahci_platform.c | 27 +++++++++++++++++++++++++++
>  include/linux/ahci_platform.h  |  3 +++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> index 8b542a8bc487..418961f954af 100644
> --- a/drivers/ata/libahci_platform.c
> +++ b/drivers/ata/libahci_platform.c
> @@ -95,6 +95,33 @@ void ahci_platform_disable_phys(struct ahci_host_priv *hpriv)
>  }
>  EXPORT_SYMBOL_GPL(ahci_platform_disable_phys);
>  
> +/**
> + * ahci_platform_find_clk - Find platform clock
> + * @hpriv: host private area to store config values
> + * @con_id: clock connection ID
> + *
> + * This function returns a pointer to the clock descriptor of the clock with
> + * the passed ID.
> + *
> + * RETURNS:
> + * Pointer to the clock descriptor on success otherwise NULL
> + */
> +struct clk *ahci_platform_find_clk(struct ahci_host_priv *hpriv, const char *con_id)
> +{
> +	struct clk *clk = NULL;
> +	int i;
> +
> +	for (i = 0; i < hpriv->n_clks; i++) {
> +		if (!strcmp(hpriv->clks[i].id, con_id)) {
> +			clk = hpriv->clks[i].clk;

			return hpriv->clks[i].clk;

> +			break;
> +		}
> +	}
> +
> +	return clk;

And then "return NULL;" here and you do not need the clk variable.

> +}
> +EXPORT_SYMBOL_GPL(ahci_platform_find_clk);
> +
>  /**
>   * ahci_platform_enable_clks - Enable platform clocks
>   * @hpriv: host private area to store config values
> diff --git a/include/linux/ahci_platform.h b/include/linux/ahci_platform.h
> index 6d7dd472d370..3418980b0341 100644
> --- a/include/linux/ahci_platform.h
> +++ b/include/linux/ahci_platform.h
> @@ -13,6 +13,7 @@
>  
>  #include <linux/compiler.h>
>  
> +struct clk;
>  struct device;
>  struct ata_port_info;
>  struct ahci_host_priv;
> @@ -21,6 +22,8 @@ struct scsi_host_template;
>  
>  int ahci_platform_enable_phys(struct ahci_host_priv *hpriv);
>  void ahci_platform_disable_phys(struct ahci_host_priv *hpriv);
> +struct clk *
> +ahci_platform_find_clk(struct ahci_host_priv *hpriv, const char *con_id);

Please make this:

struct clk *ahci_platform_find_clk(struct ahci_host_priv *hpriv,

                                   const char *con_id);

>  int ahci_platform_enable_clks(struct ahci_host_priv *hpriv);
>  void ahci_platform_disable_clks(struct ahci_host_priv *hpriv);
>  int ahci_platform_deassert_rsts(struct ahci_host_priv *hpriv);


-- 
Damien Le Moal
Western Digital Research