Re: [PATCH v2] mmc: dw_mmc: add support for RK3288

[Doug Anderson]

Addy,

On Wed, Jul 9, 2014 at 8:31 PM, Addy Ke <addy.ke@xxxxxxxxxxxxxx> wrote:
> This patch focuses on clock setting for RK3288 mmc controller.
>
> In RK3288 mmc controller, CLKDIV register can only be set 0 or 1,
> and if DDR 8bit mode, CLKDIV register must be set 1.
>
> Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx>
> ---
> changes since v1:
> - dw_mci_rk3288_setup_clock: do not call clk_get_rate(), just use the
>   host->bus_hz which is already called by dw_mmc.c, suggested by Jaehoon Chung
>
>  .../devicetree/bindings/mmc/rockchip-dw-mshc.txt   |  4 +-
>  drivers/mmc/host/dw_mmc-pltfm.c                    | 50 +++++++++++++++++++++-
>  2 files changed, 51 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt
> index c559f3f..e3f95cd 100644
> --- a/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt
> +++ b/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt
> @@ -10,7 +10,9 @@ extensions to the Synopsys Designware Mobile Storage Host Controller.
>  Required Properties:
>
>  * compatible: should be
> -       - "rockchip,rk2928-dw-mshc": for Rockchip RK2928 and following
> +       - "rockchip,rk2928-dw-mshc": for Rockchip RK2928 and following,
> +                                                       before RK3288
> +       - "rockchip,rk3288-dw-mshc": for Rockchip RK3288
>
>  Example:
>
> diff --git a/drivers/mmc/host/dw_mmc-pltfm.c b/drivers/mmc/host/dw_mmc-pltfm.c
> index d4a47a9..809c28b 100644
> --- a/drivers/mmc/host/dw_mmc-pltfm.c
> +++ b/drivers/mmc/host/dw_mmc-pltfm.c
> @@ -21,17 +21,61 @@
>  #include <linux/mmc/mmc.h>
>  #include <linux/mmc/dw_mmc.h>
>  #include <linux/of.h>
> +#include <linux/clk.h>
>
>  #include "dw_mmc.h"
>  #include "dw_mmc-pltfm.h"
>
> +#define RK3288_CLKGEN_DIV      2

Yup, this matches what I see in the TRM.  It will always divide by 2
to allow for 4 phases (picking the phases not supported yet).  Default
phase looks to be 180 degrees which is why we've (currently) got
USE_HOLD_REG hardcoded.  :)

> +
>  static void dw_mci_pltfm_prepare_command(struct dw_mci *host, u32 *cmdr)
>  {
>         *cmdr |= SDMMC_CMD_USE_HOLD_REG;
>  }
>
> -static const struct dw_mci_drv_data rockchip_drv_data = {
> +static int dw_mci_rk3288_setup_clock(struct dw_mci *host)
> +{
> +       host->bus_hz /= RK3288_CLKGEN_DIV;
> +
> +       return 0;
> +}
> +
> +static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
> +{
> +       int ret;
> +       unsigned int cclkin;
> +
> +       /*
> +        * cclkin: source clock of mmc controller.
> +        * bus_hz: card interface clock generated by CLKGEN.
> +        * bus_hz = cclkin / RK3288_CLKGEN_DIV;
> +        * ios->clock = (div == 0) ? bus_hz : (bus_hz / (2 * div))
> +        *
> +        * Note: div can only be 0 or 1
> +        *       if DDR50 8bit mode, div must be set 1

Makes sense.  So this function is essentially reversing the logic in
dw_mmc and making sure that we'll get the right DIV (0 or 1) in
dw_mci_setup_bus().


> +        */
> +       if ((ios->bus_width == MMC_BUS_WIDTH_8) &&
> +           (ios->timing == MMC_TIMING_UHS_DDR50 ||

Probably don't need UHS_DDR50 since (I think) you can't have an 8-bit
SD card--only MMC, right?  ...but it doesn't hurt.


> +            ios->timing == MMC_TIMING_MMC_DDR52))
> +               cclkin = 2 * ios->clock * RK3288_CLKGEN_DIV;
> +       else
> +               cclkin = ios->clock * RK3288_CLKGEN_DIV;
> +
> +       ret = clk_set_rate(host->ciu_clk, cclkin);
> +       if (ret)
> +               dev_warn(host->dev, "failed to set rate %uHz\n", ios->clock);
> +
> +       host->bus_hz = clk_get_rate(host->ciu_clk) / RK3288_CLKGEN_DIV;
> +}
> +
> +static const struct dw_mci_drv_data rk2928_drv_data = {
> +       .prepare_command        = dw_mci_pltfm_prepare_command,
> +};
> +
> +static const struct dw_mci_drv_data rk3288_drv_data = {
>         .prepare_command        = dw_mci_pltfm_prepare_command,
> +       .set_ios        = dw_mci_rk3288_set_ios,
> +       .setup_clock    = dw_mci_rk3288_setup_clock,
>  };
>
>  static const struct dw_mci_drv_data socfpga_drv_data = {
> @@ -95,7 +139,9 @@ EXPORT_SYMBOL_GPL(dw_mci_pltfm_pmops);
>  static const struct of_device_id dw_mci_pltfm_match[] = {
>         { .compatible = "snps,dw-mshc", },
>         { .compatible = "rockchip,rk2928-dw-mshc",
> -               .data = &rockchip_drv_data },
> +               .data = &rk2928_drv_data },
> +       { .compatible = "rockchip,rk3288-dw-mshc",
> +               .data = &rk3288_drv_data },
>         { .compatible = "altr,socfpga-dw-mshc",
>                 .data = &socfpga_drv_data },
>         {},

Reviewed-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Tested-by: Doug Anderson <dianders@xxxxxxxxxxxx>
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