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

Adrian Hunter
2020-11-26T08:18:42Z

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)

> + 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;
> }
>