On Wed, Aug 21, 2013 at 6:49 AM, Seungwon Jeon <[email protected]> wrote:
> Exynos's host has divider logic before 'cclk_in' to controller core.
> It means that actual clock rate of ciu clock comes from this divider
> value. So, source clock should be adjusted along with 'ciu_div' which
> indicates the host's divider ratio. Setting clock rate basically fits
> the required speed. Specially, 'cclk_in' should have double rate of
> target speed in case of DDR 8-bit mode.
I've refactored this code in ChromeOS-3.4 kernel.
Please see references to dw_mci_exynos_set_bus_hz() in:
https://gerrit.chromium.org/gerrit/#/c/57861/9/drivers/mmc/host/dw_mmc-exynos.c
Have you considered using that code? Perhaps Alim didn't point out
this work to you?
It might be easier to read here:
http://git.chromium.org/gitweb/?p=chromiumos/third_party/kernel.git;a=blob;f=drivers/mmc/host/dw_mmc.c;h=41ff5a0d79dffb488a413c51ba14024d4dda1275;hb=refs/heads/chromeos-3.4
The same code was adopted for ChromeOS-3.8 kernel tree:
http://git.chromium.org/gitweb/?p=chromiumos/third_party/kernel-next.git;a=commitdiff;h=39ae94e55a0ad4584b5ff85e2a342a5f867c4d21
http://git.chromium.org/gitweb/?p=chromiumos/third_party/kernel-next.git;a=history;f=drivers/mmc/host/dw_mmc-exynos.c;h=a8288d4c9fac8b89dadff5d4bde469c43171c9cf;hb=refs/heads/chromeos-3.8
thanks,
grant
>
> Signed-off-by: Seungwon Jeon <[email protected]>
> ---
> drivers/mmc/host/dw_mmc-exynos.c | 44 ++++++++++++++++++++++++++++---------
> 1 files changed, 33 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc-exynos.c
> b/drivers/mmc/host/dw_mmc-exynos.c
> index 90f9335..f16e2fc 100644
> --- a/drivers/mmc/host/dw_mmc-exynos.c
> +++ b/drivers/mmc/host/dw_mmc-exynos.c
> @@ -49,6 +49,7 @@ struct dw_mci_exynos_priv_data {
> u8 ciu_div;
> u32 sdr_timing;
> u32 ddr_timing;
> + u32 cur_speed;
> };
>
> static struct dw_mci_exynos_compatible {
> @@ -91,14 +92,9 @@ static int dw_mci_exynos_priv_init(struct dw_mci *host)
> static int dw_mci_exynos_setup_clock(struct dw_mci *host)
> {
> struct dw_mci_exynos_priv_data *priv = host->priv;
> + unsigned long rate = clk_get_rate(host->ciu_clk);
>
> - if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS5250)
> - host->bus_hz /= (priv->ciu_div + 1);
> - else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4412)
> - host->bus_hz /= EXYNOS4412_FIXED_CIU_CLK_DIV;
> - else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4210)
> - host->bus_hz /= EXYNOS4210_FIXED_CIU_CLK_DIV;
> -
> + host->bus_hz = rate / (priv->ciu_div + 1);
> return 0;
> }
>
> @@ -118,11 +114,31 @@ static void dw_mci_exynos_prepare_command(struct dw_mci
> *host, u32 *cmdr)
> static void dw_mci_exynos_set_ios(struct dw_mci *host, struct mmc_ios *ios)
> {
> struct dw_mci_exynos_priv_data *priv = host->priv;
> + unsigned int wanted = ios->clock;
> + unsigned long actual;
> + u8 div = priv->ciu_div + 1;
> +
>
> - if (ios->timing == MMC_TIMING_UHS_DDR50)
> + if (ios->timing == MMC_TIMING_UHS_DDR50) {
> mci_writel(host, CLKSEL, priv->ddr_timing);
> - else
> + /* Should be double rate for DDR mode */
> + if (ios->bus_width == MMC_BUS_WIDTH_8)
> + wanted <<= 1;
> + } else {
> mci_writel(host, CLKSEL, priv->sdr_timing);
> + }
> +
> + if (wanted && (priv->cur_speed != wanted)) {
> + int ret = clk_set_rate(host->ciu_clk, wanted * div);
> + if (ret)
> + dev_warn(host->dev,
> + "failed to set clk-rate %u error: %d\n",
> + wanted * div, ret);
> + actual = clk_get_rate(host->ciu_clk);
> + host->bus_hz = actual / div;
> + priv->cur_speed = wanted;
> + host->current_speed = 0;
> + }
> }
>
> static int dw_mci_exynos_parse_dt(struct dw_mci *host)
> @@ -133,8 +149,14 @@ static int dw_mci_exynos_parse_dt(struct dw_mci *host)
> u32 div = 0;
> int ret;
>
> - of_property_read_u32(np, "samsung,dw-mshc-ciu-div", &div);
> - priv->ciu_div = div;
> + if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4412)
> + priv->ciu_div = EXYNOS4412_FIXED_CIU_CLK_DIV - 1;
> + else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4210)
> + priv->ciu_div = EXYNOS4210_FIXED_CIU_CLK_DIV - 1;
> + else {
> + of_property_read_u32(np, "samsung,dw-mshc-ciu-div", &div);
> + priv->ciu_div = div;
> + }
>
> ret = of_property_read_u32_array(np,
> "samsung,dw-mshc-sdr-timing", timing, 2);
> --
> 1.7.0.4
>
>
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