[PATCH v5 01/20] mmc: sdhci: Add helper functions for UHS modes

[Jaehoon Chung]

Hi Aswath,

On 1/29/21 11:47 PM, Aswath Govindraju wrote:
> From: Faiz Abbas <faiz_abbas at ti.com>
> 
> Add a set_voltage() function which handles the switch from 3.3V to 1.8V
> for SD card UHS modes.
> 
> Signed-off-by: Faiz Abbas <faiz_abbas at ti.com>
> Signed-off-by: Aswath Govindraju <a-govindraju at ti.com>
> ---
>  drivers/mmc/sdhci.c | 73 +++++++++++++++++++++++++++++++++++++++++++++
>  include/sdhci.h     | 10 +++++++
>  2 files changed, 83 insertions(+)
> 
> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
> index 06289343124e..276b6a08e571 100644
> --- a/drivers/mmc/sdhci.c
> +++ b/drivers/mmc/sdhci.c
> @@ -20,6 +20,7 @@
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <phys2bus.h>
> +#include <power/regulator.h>
>  
>  static void sdhci_reset(struct sdhci_host *host, u8 mask)
>  {
> @@ -509,6 +510,78 @@ void sdhci_set_uhs_timing(struct sdhci_host *host)
>  	sdhci_writew(host, reg, SDHCI_HOST_CONTROL2);
>  }
>  
> +static void sdhci_set_voltage(struct sdhci_host *host)
> +{
> +	if (IS_ENABLED(CONFIG_MMC_IO_VOLTAGE)) {
> +		struct mmc *mmc = (struct mmc *)host->mmc;
> +		u32 ctrl;
> +
> +		ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +
> +		switch (mmc->signal_voltage) {
> +		case MMC_SIGNAL_VOLTAGE_330:
> +#if CONFIG_IS_ENABLED(DM_REGULATOR)
> +			if (mmc->vqmmc_supply) {
> +				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, false)) {
> +					pr_err("failed to disable vqmmc-supply\n");
> +					return;
> +				}
> +
> +				if (regulator_set_value(mmc->vqmmc_supply, 3300000)) {
> +					pr_err("failed to set vqmmc-voltage to 3.3V\n");
> +					return;
> +				}
> +
> +				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, true)) {
> +					pr_err("failed to enable vqmmc-supply\n");
> +					return;
> +				}
> +			}
> +#endif
> +			/* 3.3V regulator output should be stable within 5 ms */
> +			mdelay(5);
> +			if (IS_SD(mmc)) {
> +				ctrl &= ~SDHCI_CTRL_VDD_180;
> +				sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +			}

According to Specification, after Signal bit was changed to 0 from 1, it needs to wait for stable within 5ms.
Isn't it right that mdelay(5) locates at here?

Best Regards,
Jaehoon Chung


> +			break;
> +		case MMC_SIGNAL_VOLTAGE_180:
> +#if CONFIG_IS_ENABLED(DM_REGULATOR)
> +			if (mmc->vqmmc_supply) {
> +				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, false)) {
> +					pr_err("failed to disable vqmmc-supply\n");
> +					return;
> +				}
> +
> +				if (regulator_set_value(mmc->vqmmc_supply, 1800000)) {
> +					pr_err("failed to set vqmmc-voltage to 1.8V\n");
> +					return;
> +				}
> +
> +				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, true)) {
> +					pr_err("failed to enable vqmmc-supply\n");
> +					return;
> +				}
> +			}
> +#endif
> +			if (IS_SD(mmc)) {
> +				ctrl |= SDHCI_CTRL_VDD_180;
> +				sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +			}
> +			break;
> +		default:
> +			/* No signal voltage switch required */
> +			return;
> +		}
> +	}
> +}
> +
> +void sdhci_set_control_reg(struct sdhci_host *host)
> +{
> +	sdhci_set_voltage(host);
> +	sdhci_set_uhs_timing(host);
> +}
> +
>  #ifdef CONFIG_DM_MMC
>  static int sdhci_set_ios(struct udevice *dev)
>  {
> diff --git a/include/sdhci.h b/include/sdhci.h
> index 3e5a64981857..0ae9471ad749 100644
> --- a/include/sdhci.h
> +++ b/include/sdhci.h
> @@ -491,6 +491,16 @@ void sdhci_set_uhs_timing(struct sdhci_host *host);
>  /* Export the operations to drivers */
>  int sdhci_probe(struct udevice *dev);
>  int sdhci_set_clock(struct mmc *mmc, unsigned int clock);
> +
> +/**
> + * sdhci_set_control_reg - Set control registers
> + *
> + * This is used set up control registers for voltage level and UHS speed
> + * mode.
> + *
> + * @host: SDHCI host structure
> + */
> +void sdhci_set_control_reg(struct sdhci_host *host);
>  extern const struct dm_mmc_ops sdhci_ops;
>  #else
>  #endif
>