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Commit ea35645a authored by yangbo lu's avatar yangbo lu Committed by Ulf Hansson
Browse files

mmc: sdhci-of-esdhc: add support for signal voltage switch 



eSDHC supports signal voltage switch from 3.3v to 1.8v by
eSDHC_PROCTL[VOLT_SEL] bit. This bit changes the value of output
signal SDHC_VS, and there must be a control circuit out of eSDHC
to change the signal voltage according to SDHC_VS output signal.

Signed-off-by: default avatarYangbo Lu <yangbo.lu@nxp.com>
Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 19c3a0ef

drivers/mmc/host/sdhci-esdhc.h

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 


/* Protocol Control Register */

#define ESDHC_PROCTL			0x28

#define ESDHC_VOLT_SEL			0x00000400

#define ESDHC_CTRL_4BITBUS		(0x1 << 1)

#define ESDHC_CTRL_8BITBUS		(0x2 << 1)

#define ESDHC_CTRL_BUSWIDTH_MASK	(0x3 << 1)

drivers/mmc/host/sdhci-of-esdhc.c

+74 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/err.h>

#include <linux/io.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/delay.h>

#include <linux/module.h>

#include <linux/sys_soc.h>
@@ -560,6 +561,76 @@ static void esdhc_reset(struct sdhci_host *host, u8 mask) 
	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);

}



/* The SCFG, Supplemental Configuration Unit, provides SoC specific

 * configuration and status registers for the device. There is a

 * SDHC IO VSEL control register on SCFG for some platforms. It's

 * used to support SDHC IO voltage switching.

 */

static const struct of_device_id scfg_device_ids[] = {

	{ .compatible = "fsl,t1040-scfg", },

	{ .compatible = "fsl,ls1012a-scfg", },

	{ .compatible = "fsl,ls1046a-scfg", },

	{}

};



/* SDHC IO VSEL control register definition */

#define SCFG_SDHCIOVSELCR	0x408

#define SDHCIOVSELCR_TGLEN	0x80000000

#define SDHCIOVSELCR_VSELVAL	0x60000000

#define SDHCIOVSELCR_SDHC_VS	0x00000001



static int esdhc_signal_voltage_switch(struct mmc_host *mmc,

				       struct mmc_ios *ios)

{

	struct sdhci_host *host = mmc_priv(mmc);

	struct device_node *scfg_node;

	void __iomem *scfg_base = NULL;

	u32 sdhciovselcr;

	u32 val;



	/*

	 * Signal Voltage Switching is only applicable for Host Controllers

	 * v3.00 and above.

	 */

	if (host->version < SDHCI_SPEC_300)

		return 0;



	val = sdhci_readl(host, ESDHC_PROCTL);



	switch (ios->signal_voltage) {

	case MMC_SIGNAL_VOLTAGE_330:

		val &= ~ESDHC_VOLT_SEL;

		sdhci_writel(host, val, ESDHC_PROCTL);

		return 0;

	case MMC_SIGNAL_VOLTAGE_180:

		scfg_node = of_find_matching_node(NULL, scfg_device_ids);

		if (scfg_node)

			scfg_base = of_iomap(scfg_node, 0);

		if (scfg_base) {

			sdhciovselcr = SDHCIOVSELCR_TGLEN |

				       SDHCIOVSELCR_VSELVAL;

			iowrite32be(sdhciovselcr,

				scfg_base + SCFG_SDHCIOVSELCR);



			val |= ESDHC_VOLT_SEL;

			sdhci_writel(host, val, ESDHC_PROCTL);

			mdelay(5);



			sdhciovselcr = SDHCIOVSELCR_TGLEN |

				       SDHCIOVSELCR_SDHC_VS;

			iowrite32be(sdhciovselcr,

				scfg_base + SCFG_SDHCIOVSELCR);

			iounmap(scfg_base);

		} else {

			val |= ESDHC_VOLT_SEL;

			sdhci_writel(host, val, ESDHC_PROCTL);

		}

		return 0;

	default:

		return 0;

	}

}



#ifdef CONFIG_PM_SLEEP

static u32 esdhc_proctl;

static int esdhc_of_suspend(struct device *dev)
@@ -717,6 +788,9 @@ static int sdhci_esdhc_probe(struct platform_device *pdev) 
	if (IS_ERR(host))

		return PTR_ERR(host);



	host->mmc_host_ops.start_signal_voltage_switch =

		esdhc_signal_voltage_switch;



	esdhc_init(pdev, host);



	sdhci_get_of_property(pdev);