Re: [RFC 3/3] mmc: sdhci-pxav3: Add ->voltage_switch callback support

[Vaibhav Hiremath]

On Wednesday 02 September 2015 07:21 PM, Shawn Lin wrote:
> On 2015/9/2 3:32, Vaibhav Hiremath wrote:
> > In case PXA1928 family of devices, there is device/controller specific
> > configuration to control voltage/power on the IO pins.
> >
> > This patch implements and enables the sdhci_ops->voltage_switch()
> > callback api.
> > Note that IO pad register addresses are fetched as a memory resource.
> >
> > For example, in case of PXA1928 and family of devices, the DT property
> > would look something like,
> >
> > sdh1: sdh@d4280000 {
> >     compatible = "mrvl,pxav3-mmc";
> >     reg-names = "sdhci", "io-pwr", "io-pwr-lock-unlock";
> >     reg = <0xd4280000 0x120>,
> >         <0xd401e81c 4>,
> >         <0xd4015068 8>;
> >     ...
> > };
> >
> > Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
> > ---
> >   drivers/mmc/host/sdhci-pxav3.c | 59
> > ++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 59 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci-pxav3.c
> > b/drivers/mmc/host/sdhci-pxav3.c
> > index 5d26fe0..cebb2f9 100644
> > --- a/drivers/mmc/host/sdhci-pxav3.c
> > +++ b/drivers/mmc/host/sdhci-pxav3.c
> > @@ -63,11 +63,18 @@
> >   #define IO_PWR_AKEY_ASSAR        0xeb10
> >   #define IO_PWR_MMC1_PAD_1V8        BIT(2)
> >
> > +/* IO Power control */
> > +#define IO_PWR_AKEY_ASFAR        0xbaba
> > +#define IO_PWR_AKEY_ASSAR        0xeb10
> > +#define IO_PWR_MMC1_PAD_1V8        BIT(2)
> > +
> >   struct sdhci_pxa {
> >       struct clk *clk_core;
> >       struct clk *clk_io;
> >       u8    power_mode;
> >       void __iomem *sdio3_conf_reg;
> > +    void __iomem *io_pwr_reg;
> > +    void __iomem *io_pwr_lock_reg;
> >   };
> >
> >   /*
> > @@ -307,6 +314,38 @@ static void pxav3_set_uhs_signaling(struct
> > sdhci_host *host, unsigned int uhs)
> >           __func__, uhs, ctrl_2);
> >   }
> >
> > +static void pxav3_voltage_switch(struct sdhci_host *host,
> > +                        u8 signal_voltage)
> > +{
> > +    struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > +    struct sdhci_pxa *pxa = pltfm_host->priv;
> > +    unsigned int val;
> > +
> > +    if (!pxa->io_pwr_reg || !pxa->io_pwr_lock_reg)
> > +        return;
> > +
> > +    /* Lock register is 64 bit: First & Second access register */
> > +    writel(IO_PWR_AKEY_ASFAR, pxa->io_pwr_lock_reg);
> > +    writel(IO_PWR_AKEY_ASSAR, pxa->io_pwr_lock_reg + 4);
> > +    val = readl(pxa->io_pwr_reg);
> > +
> > +    switch (signal_voltage) {
> > +    case MMC_SIGNAL_VOLTAGE_180:
> > +    case MMC_SIGNAL_VOLTAGE_120:
> > +        val |= IO_PWR_MMC1_PAD_1V8;
> > +        break;
> > +    case MMC_SIGNAL_VOLTAGE_330:
> > +    default:
> > +        val &= ~IO_PWR_MMC1_PAD_1V8;
> > +        break;
> > +    }
> > +
> > +    writel(IO_PWR_AKEY_ASFAR, pxa->io_pwr_lock_reg);
> > +    writel(IO_PWR_AKEY_ASSAR, pxa->io_pwr_lock_reg + 4);
> > +
> > +    writel(val, pxa->io_pwr_reg);
> > +}
> > +
> >   static const struct sdhci_ops pxav3_sdhci_ops = {
> >       .set_clock            = sdhci_set_clock,
> >       .platform_send_init_74_clocks    = pxav3_gen_init_74_clocks,
> > @@ -314,6 +353,7 @@ static const struct sdhci_ops pxav3_sdhci_ops = {
> >       .set_bus_width            = sdhci_set_bus_width,
> >       .reset                = pxav3_reset,
> >       .set_uhs_signaling        = pxav3_set_uhs_signaling,
> > +    .voltage_switch            = pxav3_voltage_switch,
> >   };
> >
> >   static struct sdhci_pltfm_data sdhci_pxav3_pdata = {
> > @@ -368,6 +408,7 @@ static int sdhci_pxav3_probe(struct
> > platform_device *pdev)
> >       struct sdhci_host *host = NULL;
> >       struct sdhci_pxa *pxa = NULL;
> >       const struct of_device_id *match;
> > +    struct resource *res;
> >       int ret;
> >
> >       pxa = devm_kzalloc(&pdev->dev, sizeof(struct sdhci_pxa),
> > GFP_KERNEL);
> > @@ -408,6 +449,24 @@ static int sdhci_pxav3_probe(struct
> > platform_device *pdev)
> >               goto err_mbus_win;
> >       }
> >
> > +    res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > "io-pwr-conf");
> > +    if (res) {
> > +        pxa->io_pwr_reg = devm_ioremap_resource(&pdev->dev, res);
> > +        if (IS_ERR(pxa->io_pwr_reg)) {
> > +            ret = PTR_ERR(pxa->io_pwr_reg);
> > +            goto err_mbus_win;
> > +        }
> > +    }
>
> Hi Vaibhav,
>
> Why not get it from syscon and use regmap API to deal with it.
> IMO, that's okay, you can find examples from
> drivers/mmc/host/dw_mmc-k3.c: dw_mci_hi6220_switch_voltage

Thanks Shawn,
Good to know that, something similar is already in the mainline.

Quickly looked into the driver, and I think it looks ok and doable.
I will for couple of days, to see whether I get further comments and then
spin next version.

Thanks,
Vaibhav
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