linux-kernel - RE: [PATCH 3/9] mmc: dw_mmc: lookup for optional biu and ciu clocks

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Date:	Thu, 19 Jul 2012 19:27:25 +0900
From:	Seungwon Jeon <tgih.jun@...sung.com>
To:	'Thomas Abraham' <thomas.abraham@...aro.org>,
	linux-mmc@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	cjb@...top.org, grant.likely@...retlab.ca, rob.herring@...xeda.com,
	linux-samsung-soc@...r.kernel.org, kgene.kim@...sung.com,
	patches@...aro.org
Subject: RE: [PATCH 3/9] mmc: dw_mmc: lookup for optional biu and ciu clocks

July 17, 2012, Thomas Abraham <thomas.abraham@...aro.org> wrote:
> Some platforms allow for clock gating and control of bus interface unit clock
> and card interface unit clock. Add support for clock lookup of optional biu
> and ciu clocks for clock gating and clock speed determination.
> 
> Signed-off-by: Abhilash Kesavan <a.kesavan@...sung.com>
> Signed-off-by: Thomas Abraham <thomas.abraham@...aro.org>
> ---
>  drivers/mmc/host/dw_mmc.c  |   39 ++++++++++++++++++++++++++++++++++++---
>  include/linux/mmc/dw_mmc.h |    4 ++++
>  2 files changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index cd58063..ebd22d8 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1953,13 +1953,30 @@ int dw_mci_probe(struct dw_mci *host)
>  		return -ENODEV;
>  	}
> 
> -	if (!host->pdata->bus_hz) {
> +	host->biu_clk = clk_get(host->dev, "biu");
> +	if (IS_ERR(host->biu_clk))
> +		dev_dbg(host->dev, "biu clock not available\n");
> +	else
> +		clk_prepare_enable(host->biu_clk);
> +
> +	host->ciu_clk = clk_get(host->dev, "ciu");
> +	if (IS_ERR(host->ciu_clk))
> +		dev_dbg(host->dev, "ciu clock not available\n");
> +	else
> +		clk_prepare_enable(host->ciu_clk);
> +
> +	if (IS_ERR(host->ciu_clk))
> +		host->bus_hz = host->pdata->bus_hz;
> +	else
> +		host->bus_hz = clk_get_rate(host->ciu_clk);
I have posted similar patch some time back.
bus_hz represents input rate for cclk_in of mshc.
Host of samsung soc doesn't use input clock from system directly.
As you have introduced CLKSEL in your another patch, input clock can be changed prior to cclk_in.
For non-samsung  host, we don't need to consider this with generic way?

Thanks,
Seungwon Jeon

> +
> +	if (!host->bus_hz) {
>  		dev_err(host->dev,
>  			"Platform data must supply bus speed\n");
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto err_clk;
>  	}
> 
> -	host->bus_hz = host->pdata->bus_hz;
>  	host->quirks = host->pdata->quirks;
> 
>  	spin_lock_init(&host->lock);
> @@ -2109,6 +2126,16 @@ err_dmaunmap:
>  		regulator_disable(host->vmmc);
>  		regulator_put(host->vmmc);
>  	}
> +
> +err_clk:
> +	if (!IS_ERR(host->ciu_clk)) {
> +		clk_disable_unprepare(host->ciu_clk);
> +		clk_put(host->ciu_clk);
> +	}
> +	if (!IS_ERR(host->biu_clk)) {
> +		clk_disable_unprepare(host->biu_clk);
> +		clk_put(host->biu_clk);
> +	}
>  	return ret;
>  }
>  EXPORT_SYMBOL(dw_mci_probe);
> @@ -2142,6 +2169,12 @@ void dw_mci_remove(struct dw_mci *host)
>  		regulator_put(host->vmmc);
>  	}
> 
> +	if (!IS_ERR(host->ciu_clk))
> +		clk_disable_unprepare(host->ciu_clk);
> +	if (!IS_ERR(host->biu_clk))
> +		clk_disable_unprepare(host->biu_clk);
> +	clk_put(host->ciu_clk);
> +	clk_put(host->biu_clk);
>  }
>  EXPORT_SYMBOL(dw_mci_remove);
> 
> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index a37a573..787ad56 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -78,6 +78,8 @@ struct mmc_data;
>   * @data_offset: Set the offset of DATA register according to VERID.
>   * @dev: Device associated with the MMC controller.
>   * @pdata: Platform data associated with the MMC controller.
> + * @biu_clk: Pointer to bus interface unit clock instance.
> + * @ciu_clk: Pointer to card interface unit clock instance.
>   * @slot: Slots sharing this MMC controller.
>   * @fifo_depth: depth of FIFO.
>   * @data_shift: log2 of FIFO item size.
> @@ -158,6 +160,8 @@ struct dw_mci {
>  	u16			data_offset;
>  	struct device		*dev;
>  	struct dw_mci_board	*pdata;
> +	struct clk		*biu_clk;
> +	struct clk		*ciu_clk;
>  	struct dw_mci_slot	*slot[MAX_MCI_SLOTS];
> 
>  	/* FIFO push and pull */
> --
> 1.6.6.rc2
> 
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