[U-Boot] [PATCH v4 2/3] mmc: dw_mmc: Support bypass mode with the get_mmc_clk() method

[Pantelis Antoniou]

Hi Simon,

> On Aug 7, 2015, at 05:16 , Simon Glass <sjg at chromium.org> wrote:
> 
> Some SoCs want to adjust the input clock to the DWMMC block as a way of
> controlling the MMC bus clock. Update the get_mmc_clk() method to support
> this.
> 
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
> 
> Changes in v4:
> - Update commit message to indicate this patch is for the dw_mmc driver
> 
> drivers/mmc/dw_mmc.c        |  2 +-
> drivers/mmc/exynos_dw_mmc.c |  2 +-
> include/dwmmc.h             | 16 +++++++++++++++-
> 3 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
> index 8f28d7e..a034c3f 100644
> --- a/drivers/mmc/dw_mmc.c
> +++ b/drivers/mmc/dw_mmc.c
> @@ -248,7 +248,7 @@ static int dwmci_setup_bus(struct dwmci_host *host, u32 freq)
> 	 * host->bus_hz should be set by user.
> 	 */
> 	if (host->get_mmc_clk)
> -		sclk = host->get_mmc_clk(host);
> +		sclk = host->get_mmc_clk(host, freq);
> 	else if (host->bus_hz)
> 		sclk = host->bus_hz;
> 	else {
> diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
> index e083745..3f702ba 100644
> --- a/drivers/mmc/exynos_dw_mmc.c
> +++ b/drivers/mmc/exynos_dw_mmc.c
> @@ -39,7 +39,7 @@ static void exynos_dwmci_clksel(struct dwmci_host *host)
> 	dwmci_writel(host, DWMCI_CLKSEL, priv->sdr_timing);
> }
> 
> -unsigned int exynos_dwmci_get_clk(struct dwmci_host *host)
> +unsigned int exynos_dwmci_get_clk(struct dwmci_host *host, uint freq)
> {
> 	unsigned long sclk;
> 	int8_t clk_div;
> diff --git a/include/dwmmc.h b/include/dwmmc.h
> index 7a7555a..25cf42c 100644
> --- a/include/dwmmc.h
> +++ b/include/dwmmc.h
> @@ -163,7 +163,21 @@ struct dwmci_host {
> 
> 	void (*clksel)(struct dwmci_host *host);
> 	void (*board_init)(struct dwmci_host *host);
> -	unsigned int (*get_mmc_clk)(struct dwmci_host *host);
> +
> +	/**
> +	 * Get / set a particular MMC clock frequency
> +	 *
> +	 * This is used to request the current clock frequency of the clock
> +	 * that drives the DWMMC peripheral. The caller will then use this
> +	 * information to work out the divider it needs to achieve the
> +	 * required MMC bus clock frequency. If you want to handle the
> +	 * clock external to DWMMC, use @freq to select the frequency and
> +	 * return that value too. Then DWMMC will put itself in bypass mode.
> +	 *
> +	 * @host:	DWMMC host
> +	 * @freq:	Frequency the host is trying to achieve
> +	 */
> +	unsigned int (*get_mmc_clk)(struct dwmci_host *host, uint freq);
> 
> 	struct mmc_config cfg;
> };
> -- 
> 2.5.0.rc2.392.g76e840b

I’m applying this now. It makes sense. No, we don’t have a clock framework for now
so this will do.

Thanks

— Pantelis