[V13,12/21] mmc: sdhci-uhs2: add set_power() to support vdd2

Message ID 20231117113149.9069-13-victorshihgli@gmail.com
State New
Headers
Series Add support UHS-II for GL9755 |

Commit Message

Victor Shih Nov. 17, 2023, 11:31 a.m. UTC
  From: Victor Shih <victor.shih@genesyslogic.com.tw>

This is a UHS-II version of sdhci's set_power operation.
Use sdhci_uhs2_set_power() to set VDD2 for support UHS2 interface.
VDD2, as well as VDD, is handled here.

Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
---

Updates in V13:
 - Drop use vmmc2.
 - Modify comment message.

Updates in V10:
 - Move some definitions of PatchV9[05/23] to PatchV10[11/23].

Updates in V9:
 - Modify annotations in sdhci_get_vdd_value().

Updates in V8:
 - Adjust the position of matching brackets.
 - Add the initial value of the pwr in sdhci_uhs2_set_power().

Updates in V7:
 - Add clear the power reg before setting a new value
   in sdhci_uhs2_set_power().
 - Add MMC_VDD_34_35 case and MMC_VDD_35_36 case in sdhci_get_vdd_value().
 - Drop pwr variable in sdhci_get_vdd_value().

Updates in V6:
 - Add mmc_opt_regulator_set_ocr().
 - Remove unnecessary functions.

---
 drivers/mmc/host/sdhci-uhs2.c | 48 +++++++++++++++++++++++++++
 drivers/mmc/host/sdhci.c      | 61 +++++++++++++++++++----------------
 drivers/mmc/host/sdhci.h      |  1 +
 3 files changed, 82 insertions(+), 28 deletions(-)
  

Comments

Adrian Hunter Nov. 28, 2023, 9:12 a.m. UTC | #1
On 17/11/23 13:31, Victor Shih wrote:
> From: Victor Shih <victor.shih@genesyslogic.com.tw>
> 
> This is a UHS-II version of sdhci's set_power operation.
> Use sdhci_uhs2_set_power() to set VDD2 for support UHS2 interface.
> VDD2, as well as VDD, is handled here.
> 
> Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
> ---
> 
> Updates in V13:
>  - Drop use vmmc2.
>  - Modify comment message.
> 
> Updates in V10:
>  - Move some definitions of PatchV9[05/23] to PatchV10[11/23].
> 
> Updates in V9:
>  - Modify annotations in sdhci_get_vdd_value().
> 
> Updates in V8:
>  - Adjust the position of matching brackets.
>  - Add the initial value of the pwr in sdhci_uhs2_set_power().
> 
> Updates in V7:
>  - Add clear the power reg before setting a new value
>    in sdhci_uhs2_set_power().
>  - Add MMC_VDD_34_35 case and MMC_VDD_35_36 case in sdhci_get_vdd_value().
>  - Drop pwr variable in sdhci_get_vdd_value().
> 
> Updates in V6:
>  - Add mmc_opt_regulator_set_ocr().
>  - Remove unnecessary functions.
> 
> ---
>  drivers/mmc/host/sdhci-uhs2.c | 48 +++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci.c      | 61 +++++++++++++++++++----------------
>  drivers/mmc/host/sdhci.h      |  1 +
>  3 files changed, 82 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> index 066549526060..7d5070f58d00 100644
> --- a/drivers/mmc/host/sdhci-uhs2.c
> +++ b/drivers/mmc/host/sdhci-uhs2.c
> @@ -59,6 +59,13 @@ EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
>   *                                                                           *
>  \*****************************************************************************/
>  
> +static inline int mmc_opt_regulator_set_ocr(struct mmc_host *mmc,
> +					    struct regulator *supply,
> +					    unsigned short vdd_bit)
> +{
> +	return IS_ERR_OR_NULL(supply) ? 0 : mmc_regulator_set_ocr(mmc, supply, vdd_bit);
> +}
> +
>  bool sdhci_uhs2_mode(struct sdhci_host *host)
>  {
>  	return	host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A ||
> @@ -94,6 +101,47 @@ void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
>  }
>  EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
>  
> +static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, unsigned short vdd)
> +{
> +	struct mmc_host *mmc = host->mmc;
> +	u8 pwr = 0;
> +
> +	if (mode != MMC_POWER_OFF) {
> +		pwr = sdhci_get_vdd_value(vdd);
> +		if (!pwr)
> +			WARN(1, "%s: Invalid vdd %#x\n",
> +			     mmc_hostname(host->mmc), vdd);
> +		pwr |= SDHCI_VDD2_POWER_180;
> +	}
> +
> +	if (host->pwr == pwr)
> +		return;
> +	host->pwr = pwr;
> +
> +	if (pwr == 0) {
> +		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> +
> +		mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
> +		mmc_regulator_set_vqmmc2(mmc, &mmc->ios);

mmc_regulator_set_vqmmc2() only sets the voltage, it doesn't
disable the regulator.

> +	} else {
> +		mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
> +		/* support 1.8v only for now */
> +		mmc_regulator_set_vqmmc2(mmc, &mmc->ios);
> +
> +		/* Clear the power reg before setting a new value */
> +		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> +
> +		/* vdd first */
> +		pwr |= SDHCI_POWER_ON;
> +		sdhci_writeb(host, pwr & 0xf, SDHCI_POWER_CONTROL);
> +		mdelay(5);
> +
> +		pwr |= SDHCI_VDD2_POWER_ON;
> +		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
> +		mdelay(5);
> +	}
> +}
> +
>  /*****************************************************************************\
>   *                                                                           *
>   * Driver init/exit                                                          *
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 27ea5b875c29..4d50cac7717d 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -23,7 +23,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/of.h>
> -
> +#include <linux/bug.h>
>  #include <linux/leds.h>
>  
>  #include <linux/mmc/mmc.h>
> @@ -2061,41 +2061,46 @@ static void sdhci_set_power_reg(struct sdhci_host *host, unsigned char mode,
>  		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
>  }
>  
> +unsigned short sdhci_get_vdd_value(unsigned short vdd)
> +{
> +	switch (1 << vdd) {
> +	case MMC_VDD_165_195:
> +	/*
> +	 * Without a regulator, SDHCI does not support 2.0v
> +	 * so we only get here if the driver deliberately
> +	 * added the 2.0v range to ocr_avail. Map it to 1.8v
> +	 * for the purpose of turning on the power.
> +	 */
> +	case MMC_VDD_20_21:
> +		return SDHCI_POWER_180;
> +	case MMC_VDD_29_30:
> +	case MMC_VDD_30_31:
> +		return SDHCI_POWER_300;
> +	case MMC_VDD_32_33:
> +	case MMC_VDD_33_34:
> +	/*
> +	 * 3.4V ~ 3.6V are valid only for those platforms where it's
> +	 * known that the voltage range is supported by hardware.
> +	 */
> +	case MMC_VDD_34_35:
> +	case MMC_VDD_35_36:
> +		return SDHCI_POWER_330;
> +	default:
> +		return 0;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(sdhci_get_vdd_value);
> +
>  void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
>  			   unsigned short vdd)
>  {
>  	u8 pwr = 0;
>  
>  	if (mode != MMC_POWER_OFF) {
> -		switch (1 << vdd) {
> -		case MMC_VDD_165_195:
> -		/*
> -		 * Without a regulator, SDHCI does not support 2.0v
> -		 * so we only get here if the driver deliberately
> -		 * added the 2.0v range to ocr_avail. Map it to 1.8v
> -		 * for the purpose of turning on the power.
> -		 */
> -		case MMC_VDD_20_21:
> -			pwr = SDHCI_POWER_180;
> -			break;
> -		case MMC_VDD_29_30:
> -		case MMC_VDD_30_31:
> -			pwr = SDHCI_POWER_300;
> -			break;
> -		case MMC_VDD_32_33:
> -		case MMC_VDD_33_34:
> -		/*
> -		 * 3.4 ~ 3.6V are valid only for those platforms where it's
> -		 * known that the voltage range is supported by hardware.
> -		 */
> -		case MMC_VDD_34_35:
> -		case MMC_VDD_35_36:
> -			pwr = SDHCI_POWER_330;
> -			break;
> -		default:
> +		pwr = sdhci_get_vdd_value(vdd);
> +		if (!pwr) {
>  			WARN(1, "%s: Invalid vdd %#x\n",
>  			     mmc_hostname(host->mmc), vdd);
> -			break;
>  		}
>  	}
>  
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 782c399fae15..cdb418d97c4d 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -837,6 +837,7 @@ void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
>  void sdhci_set_power_and_bus_voltage(struct sdhci_host *host,
>  				     unsigned char mode,
>  				     unsigned short vdd);
> +unsigned short sdhci_get_vdd_value(unsigned short vdd);
>  void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
>  			   unsigned short vdd);
>  int sdhci_get_cd_nogpio(struct mmc_host *mmc);
  
Victor Shih Jan. 8, 2024, 10:45 a.m. UTC | #2
On Tue, Nov 28, 2023 at 5:12 PM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 17/11/23 13:31, Victor Shih wrote:
> > From: Victor Shih <victor.shih@genesyslogic.com.tw>
> >
> > This is a UHS-II version of sdhci's set_power operation.
> > Use sdhci_uhs2_set_power() to set VDD2 for support UHS2 interface.
> > VDD2, as well as VDD, is handled here.
> >
> > Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
> > ---
> >
> > Updates in V13:
> >  - Drop use vmmc2.
> >  - Modify comment message.
> >
> > Updates in V10:
> >  - Move some definitions of PatchV9[05/23] to PatchV10[11/23].
> >
> > Updates in V9:
> >  - Modify annotations in sdhci_get_vdd_value().
> >
> > Updates in V8:
> >  - Adjust the position of matching brackets.
> >  - Add the initial value of the pwr in sdhci_uhs2_set_power().
> >
> > Updates in V7:
> >  - Add clear the power reg before setting a new value
> >    in sdhci_uhs2_set_power().
> >  - Add MMC_VDD_34_35 case and MMC_VDD_35_36 case in sdhci_get_vdd_value().
> >  - Drop pwr variable in sdhci_get_vdd_value().
> >
> > Updates in V6:
> >  - Add mmc_opt_regulator_set_ocr().
> >  - Remove unnecessary functions.
> >
> > ---
> >  drivers/mmc/host/sdhci-uhs2.c | 48 +++++++++++++++++++++++++++
> >  drivers/mmc/host/sdhci.c      | 61 +++++++++++++++++++----------------
> >  drivers/mmc/host/sdhci.h      |  1 +
> >  3 files changed, 82 insertions(+), 28 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> > index 066549526060..7d5070f58d00 100644
> > --- a/drivers/mmc/host/sdhci-uhs2.c
> > +++ b/drivers/mmc/host/sdhci-uhs2.c
> > @@ -59,6 +59,13 @@ EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
> >   *                                                                           *
> >  \*****************************************************************************/
> >
> > +static inline int mmc_opt_regulator_set_ocr(struct mmc_host *mmc,
> > +                                         struct regulator *supply,
> > +                                         unsigned short vdd_bit)
> > +{
> > +     return IS_ERR_OR_NULL(supply) ? 0 : mmc_regulator_set_ocr(mmc, supply, vdd_bit);
> > +}
> > +
> >  bool sdhci_uhs2_mode(struct sdhci_host *host)
> >  {
> >       return  host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A ||
> > @@ -94,6 +101,47 @@ void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
> >  }
> >  EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
> >
> > +static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, unsigned short vdd)
> > +{
> > +     struct mmc_host *mmc = host->mmc;
> > +     u8 pwr = 0;
> > +
> > +     if (mode != MMC_POWER_OFF) {
> > +             pwr = sdhci_get_vdd_value(vdd);
> > +             if (!pwr)
> > +                     WARN(1, "%s: Invalid vdd %#x\n",
> > +                          mmc_hostname(host->mmc), vdd);
> > +             pwr |= SDHCI_VDD2_POWER_180;
> > +     }
> > +
> > +     if (host->pwr == pwr)
> > +             return;
> > +     host->pwr = pwr;
> > +
> > +     if (pwr == 0) {
> > +             sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> > +
> > +             mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
> > +             mmc_regulator_set_vqmmc2(mmc, &mmc->ios);
>
> mmc_regulator_set_vqmmc2() only sets the voltage, it doesn't
> disable the regulator.
>

Hi, Ulf

Would you have any idea about using the  mmc_regulator_set_vqmmc2()
to disable the regulator?

Thanks, Victor Shih

> > +     } else {
> > +             mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
> > +             /* support 1.8v only for now */
> > +             mmc_regulator_set_vqmmc2(mmc, &mmc->ios);
> > +
> > +             /* Clear the power reg before setting a new value */
> > +             sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> > +
> > +             /* vdd first */
> > +             pwr |= SDHCI_POWER_ON;
> > +             sdhci_writeb(host, pwr & 0xf, SDHCI_POWER_CONTROL);
> > +             mdelay(5);
> > +
> > +             pwr |= SDHCI_VDD2_POWER_ON;
> > +             sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
> > +             mdelay(5);
> > +     }
> > +}
> > +
> >  /*****************************************************************************\
> >   *                                                                           *
> >   * Driver init/exit                                                          *
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 27ea5b875c29..4d50cac7717d 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -23,7 +23,7 @@
> >  #include <linux/regulator/consumer.h>
> >  #include <linux/pm_runtime.h>
> >  #include <linux/of.h>
> > -
> > +#include <linux/bug.h>
> >  #include <linux/leds.h>
> >
> >  #include <linux/mmc/mmc.h>
> > @@ -2061,41 +2061,46 @@ static void sdhci_set_power_reg(struct sdhci_host *host, unsigned char mode,
> >               sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> >  }
> >
> > +unsigned short sdhci_get_vdd_value(unsigned short vdd)
> > +{
> > +     switch (1 << vdd) {
> > +     case MMC_VDD_165_195:
> > +     /*
> > +      * Without a regulator, SDHCI does not support 2.0v
> > +      * so we only get here if the driver deliberately
> > +      * added the 2.0v range to ocr_avail. Map it to 1.8v
> > +      * for the purpose of turning on the power.
> > +      */
> > +     case MMC_VDD_20_21:
> > +             return SDHCI_POWER_180;
> > +     case MMC_VDD_29_30:
> > +     case MMC_VDD_30_31:
> > +             return SDHCI_POWER_300;
> > +     case MMC_VDD_32_33:
> > +     case MMC_VDD_33_34:
> > +     /*
> > +      * 3.4V ~ 3.6V are valid only for those platforms where it's
> > +      * known that the voltage range is supported by hardware.
> > +      */
> > +     case MMC_VDD_34_35:
> > +     case MMC_VDD_35_36:
> > +             return SDHCI_POWER_330;
> > +     default:
> > +             return 0;
> > +     }
> > +}
> > +EXPORT_SYMBOL_GPL(sdhci_get_vdd_value);
> > +
> >  void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> >                          unsigned short vdd)
> >  {
> >       u8 pwr = 0;
> >
> >       if (mode != MMC_POWER_OFF) {
> > -             switch (1 << vdd) {
> > -             case MMC_VDD_165_195:
> > -             /*
> > -              * Without a regulator, SDHCI does not support 2.0v
> > -              * so we only get here if the driver deliberately
> > -              * added the 2.0v range to ocr_avail. Map it to 1.8v
> > -              * for the purpose of turning on the power.
> > -              */
> > -             case MMC_VDD_20_21:
> > -                     pwr = SDHCI_POWER_180;
> > -                     break;
> > -             case MMC_VDD_29_30:
> > -             case MMC_VDD_30_31:
> > -                     pwr = SDHCI_POWER_300;
> > -                     break;
> > -             case MMC_VDD_32_33:
> > -             case MMC_VDD_33_34:
> > -             /*
> > -              * 3.4 ~ 3.6V are valid only for those platforms where it's
> > -              * known that the voltage range is supported by hardware.
> > -              */
> > -             case MMC_VDD_34_35:
> > -             case MMC_VDD_35_36:
> > -                     pwr = SDHCI_POWER_330;
> > -                     break;
> > -             default:
> > +             pwr = sdhci_get_vdd_value(vdd);
> > +             if (!pwr) {
> >                       WARN(1, "%s: Invalid vdd %#x\n",
> >                            mmc_hostname(host->mmc), vdd);
> > -                     break;
> >               }
> >       }
> >
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index 782c399fae15..cdb418d97c4d 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -837,6 +837,7 @@ void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
> >  void sdhci_set_power_and_bus_voltage(struct sdhci_host *host,
> >                                    unsigned char mode,
> >                                    unsigned short vdd);
> > +unsigned short sdhci_get_vdd_value(unsigned short vdd);
> >  void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> >                          unsigned short vdd);
> >  int sdhci_get_cd_nogpio(struct mmc_host *mmc);
>
  

Patch

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 066549526060..7d5070f58d00 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -59,6 +59,13 @@  EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
  *                                                                           *
 \*****************************************************************************/
 
+static inline int mmc_opt_regulator_set_ocr(struct mmc_host *mmc,
+					    struct regulator *supply,
+					    unsigned short vdd_bit)
+{
+	return IS_ERR_OR_NULL(supply) ? 0 : mmc_regulator_set_ocr(mmc, supply, vdd_bit);
+}
+
 bool sdhci_uhs2_mode(struct sdhci_host *host)
 {
 	return	host->mmc->ios.timing == MMC_TIMING_UHS2_SPEED_A ||
@@ -94,6 +101,47 @@  void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
 }
 EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
 
+static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, unsigned short vdd)
+{
+	struct mmc_host *mmc = host->mmc;
+	u8 pwr = 0;
+
+	if (mode != MMC_POWER_OFF) {
+		pwr = sdhci_get_vdd_value(vdd);
+		if (!pwr)
+			WARN(1, "%s: Invalid vdd %#x\n",
+			     mmc_hostname(host->mmc), vdd);
+		pwr |= SDHCI_VDD2_POWER_180;
+	}
+
+	if (host->pwr == pwr)
+		return;
+	host->pwr = pwr;
+
+	if (pwr == 0) {
+		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
+
+		mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
+		mmc_regulator_set_vqmmc2(mmc, &mmc->ios);
+	} else {
+		mmc_opt_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
+		/* support 1.8v only for now */
+		mmc_regulator_set_vqmmc2(mmc, &mmc->ios);
+
+		/* Clear the power reg before setting a new value */
+		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
+
+		/* vdd first */
+		pwr |= SDHCI_POWER_ON;
+		sdhci_writeb(host, pwr & 0xf, SDHCI_POWER_CONTROL);
+		mdelay(5);
+
+		pwr |= SDHCI_VDD2_POWER_ON;
+		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
+		mdelay(5);
+	}
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Driver init/exit                                                          *
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 27ea5b875c29..4d50cac7717d 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -23,7 +23,7 @@ 
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
-
+#include <linux/bug.h>
 #include <linux/leds.h>
 
 #include <linux/mmc/mmc.h>
@@ -2061,41 +2061,46 @@  static void sdhci_set_power_reg(struct sdhci_host *host, unsigned char mode,
 		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
 }
 
+unsigned short sdhci_get_vdd_value(unsigned short vdd)
+{
+	switch (1 << vdd) {
+	case MMC_VDD_165_195:
+	/*
+	 * Without a regulator, SDHCI does not support 2.0v
+	 * so we only get here if the driver deliberately
+	 * added the 2.0v range to ocr_avail. Map it to 1.8v
+	 * for the purpose of turning on the power.
+	 */
+	case MMC_VDD_20_21:
+		return SDHCI_POWER_180;
+	case MMC_VDD_29_30:
+	case MMC_VDD_30_31:
+		return SDHCI_POWER_300;
+	case MMC_VDD_32_33:
+	case MMC_VDD_33_34:
+	/*
+	 * 3.4V ~ 3.6V are valid only for those platforms where it's
+	 * known that the voltage range is supported by hardware.
+	 */
+	case MMC_VDD_34_35:
+	case MMC_VDD_35_36:
+		return SDHCI_POWER_330;
+	default:
+		return 0;
+	}
+}
+EXPORT_SYMBOL_GPL(sdhci_get_vdd_value);
+
 void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
 			   unsigned short vdd)
 {
 	u8 pwr = 0;
 
 	if (mode != MMC_POWER_OFF) {
-		switch (1 << vdd) {
-		case MMC_VDD_165_195:
-		/*
-		 * Without a regulator, SDHCI does not support 2.0v
-		 * so we only get here if the driver deliberately
-		 * added the 2.0v range to ocr_avail. Map it to 1.8v
-		 * for the purpose of turning on the power.
-		 */
-		case MMC_VDD_20_21:
-			pwr = SDHCI_POWER_180;
-			break;
-		case MMC_VDD_29_30:
-		case MMC_VDD_30_31:
-			pwr = SDHCI_POWER_300;
-			break;
-		case MMC_VDD_32_33:
-		case MMC_VDD_33_34:
-		/*
-		 * 3.4 ~ 3.6V are valid only for those platforms where it's
-		 * known that the voltage range is supported by hardware.
-		 */
-		case MMC_VDD_34_35:
-		case MMC_VDD_35_36:
-			pwr = SDHCI_POWER_330;
-			break;
-		default:
+		pwr = sdhci_get_vdd_value(vdd);
+		if (!pwr) {
 			WARN(1, "%s: Invalid vdd %#x\n",
 			     mmc_hostname(host->mmc), vdd);
-			break;
 		}
 	}
 
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 782c399fae15..cdb418d97c4d 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -837,6 +837,7 @@  void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
 void sdhci_set_power_and_bus_voltage(struct sdhci_host *host,
 				     unsigned char mode,
 				     unsigned short vdd);
+unsigned short sdhci_get_vdd_value(unsigned short vdd);
 void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
 			   unsigned short vdd);
 int sdhci_get_cd_nogpio(struct mmc_host *mmc);