Hi Adrian, > -----Original Message----- > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc- > owner@xxxxxxxxxxxxxxx] On Behalf Of Adrian Hunter > Sent: Monday, April 10, 2017 8:38 PM > To: Y.B. Lu; linux-mmc@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; ulf.hansson@xxxxxxxxxx; Rob Herring; > Mark Rutland; Catalin Marinas; Will Deacon > Cc: Xiaobo Xie > Subject: Re: [v3, 2/7] mmc: sdhci-of-esdhc: add support for signal > voltage switch > > On 27/03/17 10:49, Yangbo Lu wrote: > > 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: Yangbo Lu <yangbo.lu@xxxxxxx> > > Apart from minor comment below: > > Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> > > > --- > > Changes for v2: > > - Used Adrain's method to support voltage switching: > > host->mmc_host_ops.start_signal_voltage_switch = > > esdhc_signal_voltage_switch; Changes for v3: > > - Put .start_signal_voltage_switch assigning after IS_ERR(host) > check. > > --- > > drivers/mmc/host/sdhci-esdhc.h | 1 + > > drivers/mmc/host/sdhci-of-esdhc.c | 74 > > +++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 75 insertions(+) > > > > diff --git a/drivers/mmc/host/sdhci-esdhc.h > > b/drivers/mmc/host/sdhci-esdhc.h index 5343fc0..6869567 100644 > > --- a/drivers/mmc/host/sdhci-esdhc.h > > +++ b/drivers/mmc/host/sdhci-esdhc.h > > @@ -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) > > diff --git a/drivers/mmc/host/sdhci-of-esdhc.c > > b/drivers/mmc/host/sdhci-of-esdhc.c > > index 7ce1caf..a70499a 100644 > > --- a/drivers/mmc/host/sdhci-of-esdhc.c > > +++ b/drivers/mmc/host/sdhci-of-esdhc.c > > @@ -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> > > @@ -559,6 +560,76 @@ 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); > > In other places there is support for little endian also, so why not here? [Lu Yangbo-B47093] The SCFG unit is always a big-endian module on both ARM and PPC QorIQ platforms. There is little possibility to have little-endian in future. > > > + > > + 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) @@ -714,6 +785,9 @@ > > 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); > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
