[PATCH 2/2] mmc: sdhci-brcmstb: Add ability to increase max clock rate for 72116b0

[Ulf Hansson]

On Fri, 13 May 2022 at 22:19, Kamal Dasu <kdasu.kdev at gmail.com> wrote:
>
> From: Al Cooper <alcooperx at gmail.com>
>
> The 72116B0 has improved SDIO controllers that allow the max clock
> rate to be increased from a max of 100MHz to a max of 150MHz. The
> driver will need to get the clock and increase it's default rate
> and override the caps register, that still indicates a max of 100MHz.
> The new clock will be named "sdio_freq" in the DT node's "clock-names"
> list. The driver will use a DT property, "clock-frequency", to

/s/clock-frequency/max-frequency


> enable this functionality and will get the actual rate in MHz
> from the property to allow various speeds to be requested.
>
> Signed-off-by: Al Cooper <alcooperx at gmail.com>
> Signed-off-by: Kamal Dasu <kdasu.kdev at gmail.com>
> ---
>  drivers/mmc/host/sdhci-brcmstb.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-brcmstb.c b/drivers/mmc/host/sdhci-brcmstb.c
> index 8eb57de48e0c..a1ffdd3f1640 100644
> --- a/drivers/mmc/host/sdhci-brcmstb.c
> +++ b/drivers/mmc/host/sdhci-brcmstb.c
> @@ -250,6 +250,9 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
>         struct sdhci_pltfm_host *pltfm_host;
>         const struct of_device_id *match;
>         struct sdhci_brcmstb_priv *priv;
> +       struct clk *master_clk;
> +       u32 base_clock_hz = 0;
> +       u32 actual_clock_mhz;
>         struct sdhci_host *host;
>         struct resource *iomem;
>         struct clk *clk;
> @@ -330,6 +333,33 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
>         if (match_priv->flags & BRCMSTB_MATCH_FLAGS_BROKEN_TIMEOUT)
>                 host->quirks |= SDHCI_QUIRK_BROKEN_TIMEOUT_VAL;
>
> +       /* Change the base clock frequency if the DT property exists */
> +       if (device_property_read_u32(&pdev->dev, "max-frequency",
> +                                    &base_clock_hz) != 0)
> +               goto add_host;

The max-frequency DT property is already being parsed by
mmc_of_parse() and the value is put in host->mmc->f_max. You could
probably use that instead, right?

> +
> +       master_clk = devm_clk_get(&pdev->dev, "sdio_freq");
> +       if (IS_ERR(master_clk)) {
> +               dev_warn(&pdev->dev, "Clock for \"sdio_freq\" not found\n");
> +               goto add_host;
> +       } else {
> +               res = clk_prepare_enable(master_clk);
> +               if (res)
> +                       goto err;
> +       }
> +
> +       /* set improved clock rate */
> +       clk_set_rate(master_clk, base_clock_hz);
> +       actual_clock_mhz = clk_get_rate(master_clk) / 1000000;
> +
> +       host->caps &= ~SDHCI_CLOCK_V3_BASE_MASK;
> +       host->caps |= (actual_clock_mhz << SDHCI_CLOCK_BASE_SHIFT);
> +       /* Disable presets because they are now incorrect */
> +       host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN;
> +       dev_dbg(&pdev->dev, "Base Clock Frequency changed to %dMHz\n",
> +               actual_clock_mhz);
> +
> +add_host:
>         res = sdhci_brcmstb_add_host(host, priv);
>         if (res)
>                 goto err;
> --
> 2.17.1
>

Kind regards
Uffe