Re: [PATCH v5 07/12] mmc: sdhci-msm: Implement set_clock callback for sdhci-msm

[Adrian Hunter <adrian.hunter-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On 05/10/16 17:40, Ritesh Harjani wrote:
> sdhci-msm controller may have different clk-rates for each
> bus speed mode. Thus implement set_clock callback for
> sdhci-msm driver.
> 
> Signed-off-by: Sahitya Tummala <stummala-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Signed-off-by: Ritesh Harjani <riteshh-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  drivers/mmc/host/sdhci-msm.c | 110 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 109 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 542ddad..9d18cf0 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -84,6 +84,7 @@ struct sdhci_msm_host {
>  	struct clk *bus_clk;	/* SDHC bus voter clock */
>  	u32 *clk_table;
>  	int clk_table_sz;
> +	u32 clk_rate;
>  	struct mmc_host *mmc;
>  	bool use_14lpp_dll_reset;
>  };
> @@ -588,6 +589,113 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host)
>  	}
>  }
>  
> +static unsigned int sdhci_msm_get_msm_clk_rate(struct sdhci_host *host,
> +					u32 req_clk)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> +	int count;
> +	unsigned int sel_clk = -1;
> +
> +	if (!msm_host->clk_table)
> +		return clk_round_rate(msm_host->clk, ULONG_MAX);
> +
> +	count = msm_host->clk_table_sz;
> +
> +	while (count--) {
> +		sel_clk = msm_host->clk_table[count];
> +		if (req_clk >= sel_clk)
> +			return sel_clk;
> +	}
> +
> +	return sel_clk;
> +}
> +
> +/**
> + * __sdhci_msm_set_clock - sdhci_msm clock control.
> + *
> + * Description:
> + * Implement MSM version of sdhci_set_clock.
> + * This is required since MSM controller does not
> + * use internal divider and instead directly control
> + * the GCC clock as per HW recommendation.
> + **/
> +void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> +	u16 clk;
> +	unsigned long timeout;
> +
> +	/*
> +	 * Keep actual_clock as zero -
> +	 * - since there is no divider used so no need of having actual_clock.
> +	 * - MSM controller uses SDCLK for data timeout calculation. If
> +	 *   actual_clock is zero, host->clock is taken for calculation.
> +	 */
> +	host->mmc->actual_clock = 0;
> +
> +	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> +
> +	if (clock == 0)
> +		return;
> +
> +	/*
> +	 * MSM controller do not use clock divider.
> +	 * Thus read SDHCI_CLOCK_CONTROL and only enable
> +	 * clock with no divider value programmed.
> +	 */
> +	clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +
> +	clk |= SDHCI_CLOCK_INT_EN;
> +	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +
> +	/* Wait max 20 ms */
> +	timeout = 20;
> +	while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
> +		& SDHCI_CLOCK_INT_STABLE)) {
> +		if (timeout == 0) {
> +			pr_err("%s: Internal clock never stabilised.\n",
> +			       mmc_hostname(host->mmc));
> +			return;
> +		}
> +		timeout--;
> +		mdelay(1);
> +	}
> +
> +	clk |= SDHCI_CLOCK_CARD_EN;
> +	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +}
> +
> +static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> +	u32 msm_clock;
> +	int rc;
> +
> +	if (!clock)

Wouldn't you still need to set msm_host->clk_rate = clock in this case

> +		goto out;
> +
> +	spin_unlock_irq(&host->lock);
> +	if ((clock != msm_host->clk_rate) && msm_host->clk_table) {
> +		msm_clock = sdhci_msm_get_msm_clk_rate(host, clock);
> +		rc = clk_set_rate(msm_host->clk, msm_clock);
> +		if (rc) {
> +			pr_err("%s: failed to set clock at rate %u, requested clock rate %u\n",
> +				mmc_hostname(host->mmc), msm_clock, clock);
> +			goto out;
> +		}
> +		msm_host->clk_rate = clock;
> +		pr_debug("%s: setting clock at rate %lu\n",
> +			mmc_hostname(host->mmc), clk_get_rate(msm_host->clk));
> +	}
> +
> +	spin_lock_irq(&host->lock);
> +out:
> +	if (!msm_host->clk_table)
> +		return sdhci_set_clock(host, clock);

Could put the above 2 lines at the start and then no need to check
msm_host->clk_table again.

> +	__sdhci_msm_set_clock(host, clock);
> +}
> +
>  static const struct of_device_id sdhci_msm_dt_match[] = {
>  	{ .compatible = "qcom,sdhci-msm-v4" },
>  	{},
> @@ -598,7 +706,7 @@ MODULE_DEVICE_TABLE(of, sdhci_msm_dt_match);
>  static const struct sdhci_ops sdhci_msm_ops = {
>  	.platform_execute_tuning = sdhci_msm_execute_tuning,
>  	.reset = sdhci_reset,
> -	.set_clock = sdhci_set_clock,
> +	.set_clock = sdhci_msm_set_clock,
>  	.get_min_clock = sdhci_msm_get_min_clock,
>  	.get_max_clock = sdhci_msm_get_max_clock,
>  	.set_bus_width = sdhci_set_bus_width,
> 

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html