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

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Message-ID: <14ad8c85-0dbb-b023-6a0d-7805cc6f0ab8@intel.com>
Date:   Thu, 26 Nov 2020 10:17:59 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        ben.chuang@...esyslogic.com.tw, greg.tu@...esyslogic.com.tw
Subject: Re: [RFC PATCH v3.1 18/27] mmc: sdhci-uhs2: add clock operations

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@...esyslogic.com.tw>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.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;
>  }
>