Re: [RFC PATCH v3.1 18/27] mmc: sdhci-uhs2: add clock operations

AKASHI Takahiro
2020-12-01T02:27:58Z

On Thu, Nov 26, 2020 at 10:17:59AM +0200, Adrian Hunter wrote:
> On 6/11/20 4:27 am, AKASHI Takahiro wrote:
> > This is a sdhci version of mmc's uhs2_[enable|disable]_clk operations.
> >
> > Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> > drivers/mmc/host/sdhci-uhs2.c | 41 +++++++++++++++++++++++++++++++++++
> > 1 file changed, 41 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> > index 994dff967e85..55362ace1857 100644
> > --- a/drivers/mmc/host/sdhci-uhs2.c
> > +++ b/drivers/mmc/host/sdhci-uhs2.c
> > @@ -11,6 +11,7 @@
> > */
> >
> > #include <linux/delay.h>
> > +#include <linux/ktime.h>
> > #include <linux/module.h>
> >
> > #include "sdhci.h"
> > @@ -385,6 +386,42 @@ void sdhci_uhs2_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> > __sdhci_uhs2_set_ios(mmc, ios);
> > }
> >
> > +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);
>
> Can use read_poll_timeout(sdhci_readw,..., host, SDHCI_CLOCK_CONTROL)

Okay.

-Takahiro Akashi

> > + 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);
> > + }
> > +}
> > +
> > /*****************************************************************************\
> > * *
> > * Driver init/exit *
> > @@ -556,6 +593,10 @@ static int sdhci_uhs2_host_ops_init(struct sdhci_host *host)
> >
> > if (!host->mmc_host_ops.uhs2_detect_init)
> > host->mmc_host_ops.uhs2_detect_init = sdhci_uhs2_do_detect_init;
> > + if (!host->mmc_host_ops.uhs2_disable_clk)
> > + host->mmc_host_ops.uhs2_disable_clk = sdhci_uhs2_disable_clk;
> > + if (!host->mmc_host_ops.uhs2_enable_clk)
> > + host->mmc_host_ops.uhs2_enable_clk = sdhci_uhs2_enable_clk;
> >
> > return 0;
> > }
> >
>