linux-kernel - Re: [PATCH 1/7] mmc: dw_mmc: lookup for optional biu and ciu clocks

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Date:	Wed, 2 May 2012 15:53:53 +0100
From:	James Hogan <james@...anarts.com>
To:	Thomas Abraham <thomas.abraham@...aro.org>
Cc:	linux-mmc@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	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 1/7] mmc: dw_mmc: lookup for optional biu and ciu clocks

Hi

On 2 May 2012 06:07, 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  |   35 +++++++++++++++++++++++++++++++----
>  include/linux/mmc/dw_mmc.h |    4 ++++
>  2 files changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 1532357..036846f 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1938,19 +1938,35 @@ int dw_mci_probe(struct dw_mci *host)
>                return -ENODEV;
>        }
>
> -       if (!host->pdata->bus_hz) {
> +       host->biu_clk = clk_get(&host->dev, "biu");

These clock names sound quite platform specific (what if they're
called something else on another platform, or another platform has
separate ones for different instantiations of the block?). Perhaps the
clk names should get passed in through platform data. I haven't looked
how other drivers handle that though.

> +       if (IS_ERR(host->biu_clk))
> +               dev_info(&host->dev, "biu clock not available\n");

In this case, should it set host->biu_clk to NULL or are clk_disable
and clk_put guaranteed to handle an IS_ERR value?

> +       else
> +               clk_enable(host->biu_clk);
> +
> +       host->ciu_clk = clk_get(&host->dev, "ciu");
> +       if (IS_ERR(host->ciu_clk))
> +               dev_info(&host->dev, "ciu clock not available\n");

same here

> +       else
> +               clk_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);
> +
> +       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);
>        INIT_LIST_HEAD(&host->queue);
>
> -
>        host->dma_ops = host->pdata->dma_ops;
>        dw_mci_init_dma(host);
>
> @@ -2095,6 +2111,13 @@ err_dmaunmap:
>                regulator_disable(host->vmmc);
>                regulator_put(host->vmmc);
>        }
> +       kfree(host);

what's this about?

> +
> +err_clk:
> +       clk_disable(host->ciu_clk);
> +       clk_disable(host->biu_clk);
> +       clk_put(host->ciu_clk);
> +       clk_put(host->biu_clk);
>        return ret;
>  }
>  EXPORT_SYMBOL(dw_mci_probe);
> @@ -2128,6 +2151,10 @@ void dw_mci_remove(struct dw_mci *host)
>                regulator_put(host->vmmc);
>        }
>
> +       clk_disable(host->ciu_clk);
> +       clk_disable(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 7a7ebd3..fa9a139 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 */
> --
> 1.7.5.4
>
> --
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-- 
James Hogan
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