linux-kernel - Re: [PATCH V13 11/21] mmc: sdhci-uhs2: add reset function and uhs2

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Message-ID: <228dab31-8073-44f5-98ac-35aedb508e04@intel.com>
Date:   Tue, 28 Nov 2023 11:11:23 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Victor Shih <victorshihgli@...il.com>, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        benchuanggli@...il.com, HL.Liu@...esyslogic.com.tw,
        Greg.tu@...esyslogic.com.tw, takahiro.akashi@...aro.org,
        dlunev@...omium.org, Victor Shih <victor.shih@...esyslogic.com.tw>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>
Subject: Re: [PATCH V13 11/21] mmc: sdhci-uhs2: add reset function and
 uhs2_mode function

On 17/11/23 13:31, Victor Shih wrote:
> From: Victor Shih <victor.shih@...esyslogic.com.tw>
> 
> Sdhci_uhs2_reset() does a UHS-II specific reset operation.
> 
> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Signed-off-by: Victor Shih <victor.shih@...esyslogic.com.tw>
> ---
> 
> Updates in V13:
>  - Use ios timing to stead MMC_UHS2_SUPPORT for indicate the UHS2 mode.
> 
> Updates in V8:
>  - Adjust the position of matching brackets.
> 
> Updates in V6:
>  - Remove unnecessary functions and simplify code.
> 
> ---
> 
>  drivers/mmc/host/sdhci-uhs2.c | 45 +++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci-uhs2.h |  2 ++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> index e339821d3504..ef6f02583d61 100644
> --- a/drivers/mmc/host/sdhci-uhs2.c
> +++ b/drivers/mmc/host/sdhci-uhs2.c
> @@ -10,7 +10,9 @@
>   *  Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
>   */
>  
> +#include <linux/delay.h>
>  #include <linux/module.h>
> +#include <linux/iopoll.h>
>  
>  #include "sdhci.h"
>  #include "sdhci-uhs2.h"
> @@ -21,6 +23,8 @@
>  #define SDHCI_UHS2_DUMP(f, x...) \
>  	pr_err("%s: " DRIVER_NAME ": " f, mmc_hostname(host->mmc), ## x)
>  
> +#define UHS2_RESET_TIMEOUT_100MS		100000
> +
>  void sdhci_uhs2_dump_regs(struct sdhci_host *host)
>  {
>  	if (!(sdhci_uhs2_mode(host)))
> @@ -49,6 +53,47 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
>  }
>  EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
>  
> +/*****************************************************************************\
> + *                                                                           *
> + * Low level functions                                                       *
> + *                                                                           *
> +\*****************************************************************************/
> +
> +bool sdhci_uhs2_mode(struct sdhci_host *host)
> +{
> +	return	host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A ||
> +		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_B ||
> +		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A_HD ||
> +		host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_B_HD;
> +}

This is the same as mmc_card_uhs2(host->mmc)

> +
> +/**
> + * sdhci_uhs2_reset - invoke SW reset
> + * @host: SDHCI host
> + * @mask: Control mask
> + *
> + * Invoke SW reset, depending on a bit in @mask and wait for completion.
> + */
> +void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
> +{
> +	u32 val;
> +
> +	sdhci_writew(host, mask, SDHCI_UHS2_SW_RESET);
> +
> +	if (mask & SDHCI_UHS2_SW_RESET_FULL)
> +		host->clock = 0;
> +
> +	/* hw clears the bit when it's done */
> +	if (read_poll_timeout_atomic(sdhci_readw, val, !(val & mask), 10,
> +				     UHS2_RESET_TIMEOUT_100MS, true, host, SDHCI_UHS2_SW_RESET)) {
> +		pr_warn("%s: %s: Reset 0x%x never completed. %s: clean reset bit.\n", __func__,
> +			mmc_hostname(host->mmc), (int)mask, mmc_hostname(host->mmc));
> +		sdhci_writeb(host, 0, SDHCI_UHS2_SW_RESET);
> +		return;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
> +
>  /*****************************************************************************\
>   *                                                                           *
>   * Driver init/exit                                                          *
> diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
> index 2bfe18d29bca..8253d50f7852 100644
> --- a/drivers/mmc/host/sdhci-uhs2.h
> +++ b/drivers/mmc/host/sdhci-uhs2.h
> @@ -177,5 +177,7 @@
>  struct sdhci_host;
>  
>  void sdhci_uhs2_dump_regs(struct sdhci_host *host);
> +bool sdhci_uhs2_mode(struct sdhci_host *host);
> +void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);
>  
>  #endif /* __SDHCI_UHS2_H */