linux-kernel - Re: [RFC PATCH V3 11/21] mmc: sdhci: UHS-II support, export host operations to core

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Date:   Tue, 15 Sep 2020 15:59:02 +0900
From:   AKASHI Takahiro <takahiro.akashi@...aro.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Ben Chuang <benchuanggli@...il.com>, ulf.hansson@...aro.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        ben.chuang@...esyslogic.com.tw, greg.tu@...esyslogic.com.tw
Subject: Re: [RFC PATCH V3 11/21] mmc: sdhci: UHS-II support, export host
 operations to core

On Fri, Aug 21, 2020 at 05:05:44PM +0300, Adrian Hunter wrote:
> On 10/07/20 2:10 pm, Ben Chuang wrote:
> > From: AKASHI Takahiro <takahiro.akashi@...aro.org>
> > 
> > Export sdhci-specific UHS-II operations to core.
> > 
> > Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> > ---
> >  drivers/mmc/host/sdhci.c | 70 ++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 70 insertions(+)
> > 
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index c2f6923d296c..aaf41954511a 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -2977,6 +2977,70 @@ static void sdhci_card_event(struct mmc_host *mmc)
> >  	spin_unlock_irqrestore(&host->lock, flags);
> >  }
> >  
> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_UHS2)
> > +static int sdhci_uhs2_detect_init(struct mmc_host *mmc)
> > +{
> > +	struct sdhci_host *host = mmc_priv(mmc);
> > +	int ret;
> > +
> > +	if (sdhci_uhs2_ops.do_detect_init)
> > +		ret = sdhci_uhs2_ops.do_detect_init(host);
> > +	else
> > +		return 0;
> > +
> > +	return ret;
> > +}
> > +
> > +static int sdhci_uhs2_set_reg(struct mmc_host *mmc, enum uhs2_act act)
> > +{
> > +	struct sdhci_host *host = mmc_priv(mmc);
> > +	int ret;
> > +
> > +	if (sdhci_uhs2_ops.do_set_reg)
> > +		ret = sdhci_uhs2_ops.do_set_reg(host, act);
> > +	else
> > +		ret = 0;
> > +
> > +	return ret;
> > +}
> > +
> > +static void sdhci_uhs2_disable_clk(struct mmc_host *mmc)
> > +{
> > +	struct sdhci_host *host = mmc_priv(mmc);
> > +	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +
> > +	clk &= ~SDHCI_CLOCK_CARD_EN;
> > +	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> > +}
> > +
> > +static void sdhci_uhs2_enable_clk(struct mmc_host *mmc)
> > +{
> > +	struct sdhci_host *host = mmc_priv(mmc);
> > +	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +	ktime_t timeout;
> > +
> > +	clk |= SDHCI_CLOCK_CARD_EN;
> > +	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> > +
> > +	/* Wait max 20 ms */
> > +	timeout = ktime_add_ms(ktime_get(), 20);
> > +	while (1) {
> > +		bool timedout = ktime_after(ktime_get(), timeout);
> > +
> > +		clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +		if (clk & SDHCI_CLOCK_INT_STABLE)
> > +			break;
> > +		if (timedout) {
> > +			pr_err("%s: Internal clock never stabilised.\n",
> > +			       mmc_hostname(host->mmc));
> > +			sdhci_dumpregs(host);
> > +			return;
> > +		}
> > +		udelay(10);
> > +	}
> > +}
> > +#endif /* CONFIG_MMC_SDHCI_UHS2 */
> 
> Please put all uhs2 functions in sdhci-uhs2.c and call them through sdhci_ops.

Okay although the logic itself in sdhci_uhs2_[enable|disable]_clk()
doesn't seem to be UHS-II specific.

-Takahiro Akashi

> 
> > +
> >  static const struct mmc_host_ops sdhci_ops = {
> >  	.request	= sdhci_request,
> >  	.post_req	= sdhci_post_req,
> > @@ -2992,6 +3056,12 @@ static const struct mmc_host_ops sdhci_ops = {
> >  	.execute_tuning			= sdhci_execute_tuning,
> >  	.card_event			= sdhci_card_event,
> >  	.card_busy	= sdhci_card_busy,
> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_UHS2)
> > +	.uhs2_detect_init	= sdhci_uhs2_detect_init,
> > +	.uhs2_set_reg		= sdhci_uhs2_set_reg,
> > +	.uhs2_disable_clk	= sdhci_uhs2_disable_clk,
> > +	.uhs2_enable_clk	= sdhci_uhs2_enable_clk,
> > +#endif /* CONFIG_MMC_SDHCI_UHS2 */
> >  };
> >  
> >  /*****************************************************************************\
> > 
>