linux-kernel - Re: [PATCH v4 4/5] mtd: rawnand: denali_dt: add more clocks based on IP datasheet

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Date:   Fri, 22 Jun 2018 18:54:56 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-mtd@...ts.infradead.org, Rob Herring <robh+dt@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v4 4/5] mtd: rawnand: denali_dt: add more clocks based
 on IP datasheet

On Sat, 23 Jun 2018 01:06:37 +0900
Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:

> Currently, denali_dt.c requires a single anonymous clock, but
> the Denali User's Guide requires three clocks for this IP:
> 
>  - clk: controller core clock
> 
>  - clk_x: bus interface clock
> 
>  - ecc_clk: clock at which ECC circuitry is run
> 
> This commit supports these named clocks to represent the real hardware.
> 
> For the backward compatibility, the driver still accepts a single clock
> just as before.  The clk_x_rate is taken from the clock driver again if
> the named clock "clk_x" is available.  This will happen only for future
> DT, hence the existing DT files are not affected.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>
> Reviewed-by: Richard Weinberger <richard@....at>
> Tested-by: Richard Weinberger <richard@....at>
> ---
> 
> Changes in v4: None
> Changes in v3:
>   - Change the patch order so that the bug-fix one comes the first
> 
> Changes in v2:
>   - Split patches into sensible chunks
> 
>  drivers/mtd/nand/raw/denali_dt.c | 53 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 45 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> index 6b4bd16..afaae37 100644
> --- a/drivers/mtd/nand/raw/denali_dt.c
> +++ b/drivers/mtd/nand/raw/denali_dt.c
> @@ -27,7 +27,9 @@
>  
>  struct denali_dt {
>  	struct denali_nand_info	denali;
> -	struct clk		*clk;
> +	struct clk *clk;	/* core clock */
> +	struct clk *clk_x;	/* bus interface clock */
> +	struct clk *clk_ecc;	/* ECC circuit clock */

Probably better to use a kernel-doc header to document those fields.
Anyway,

Reviewed-by: Boris Brezillon <boris.brezillon@...tlin.com>

>  };
>  
>  struct denali_dt_data {
> @@ -115,28 +117,61 @@ static int denali_dt_probe(struct platform_device *pdev)
>  	if (IS_ERR(denali->host))
>  		return PTR_ERR(denali->host);
>  
> -	dt->clk = devm_clk_get(dev, NULL);
> +	/*
> +	 * A single anonymous clock is supported for the backward compatibility.
> +	 * New platforms should support all the named clocks.
> +	 */
> +	dt->clk = devm_clk_get(dev, "nand");
> +	if (IS_ERR(dt->clk))
> +		dt->clk = devm_clk_get(dev, NULL);
>  	if (IS_ERR(dt->clk)) {
>  		dev_err(dev, "no clk available\n");
>  		return PTR_ERR(dt->clk);
>  	}
> +
> +	dt->clk_x = devm_clk_get(dev, "nand_x");
> +	if (IS_ERR(dt->clk_x))
> +		dt->clk_x = NULL;
> +
> +	dt->clk_ecc = devm_clk_get(dev, "ecc");
> +	if (IS_ERR(dt->clk_ecc))
> +		dt->clk_ecc = NULL;
> +
>  	ret = clk_prepare_enable(dt->clk);
>  	if (ret)
>  		return ret;
>  
> -	/*
> -	 * Hardcode the clock rate for the backward compatibility.
> -	 * This works for both SOCFPGA and UniPhier.
> -	 */
> -	denali->clk_x_rate = 200000000;
> +	ret = clk_prepare_enable(dt->clk_x);
> +	if (ret)
> +		goto out_disable_clk;
> +
> +	ret = clk_prepare_enable(dt->clk_ecc);
> +	if (ret)
> +		goto out_disable_clk_x;
> +
> +	if (dt->clk_x) {
> +		denali->clk_x_rate = clk_get_rate(dt->clk_x);
> +	} else {
> +		/*
> +		 * Hardcode the clock rates for the backward compatibility.
> +		 * This works for both SOCFPGA and UniPhier.
> +		 */
> +		dev_notice(dev,
> +			   "necessary clock is missing. default clock rates are used.\n");
> +		denali->clk_x_rate = 200000000;
> +	}
>  
>  	ret = denali_init(denali);
>  	if (ret)
> -		goto out_disable_clk;
> +		goto out_disable_clk_ecc;
>  
>  	platform_set_drvdata(pdev, dt);
>  	return 0;
>  
> +out_disable_clk_ecc:
> +	clk_disable_unprepare(dt->clk_ecc);
> +out_disable_clk_x:
> +	clk_disable_unprepare(dt->clk_x);
>  out_disable_clk:
>  	clk_disable_unprepare(dt->clk);
>  
> @@ -148,6 +183,8 @@ static int denali_dt_remove(struct platform_device *pdev)
>  	struct denali_dt *dt = platform_get_drvdata(pdev);
>  
>  	denali_remove(&dt->denali);
> +	clk_disable_unprepare(dt->clk_ecc);
> +	clk_disable_unprepare(dt->clk_x);
>  	clk_disable_unprepare(dt->clk);
>  
>  	return 0;