[PATCH v2 3/7] mmc: sdhci-of-k1: add SDR tuning infrastructure

[Adrian Hunter]

On 09/03/2026 13:40, Iker Pedrosa wrote:
> Add register definitions and delay line control functions to prepare for
> SDR50/SDR104 tuning support:
> 
> - Add tuning register definitions (RX_CFG, DLINE_CTRL, DLINE_CFG)
> - Add delay line control helper functions
> - Add tuning preparation function
> 
> This infrastructure prepares for implementing the SDR tuning algorithm
> while maintaining all existing functionality.
> 
> Signed-off-by: Iker Pedrosa <ikerpedrosam at gmail.com>
> ---
>  drivers/mmc/host/sdhci-of-k1.c | 61 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
> index 8af117a8e271c04a80d8dc7bb5ce12075652dd7a..79cb7c8d0b6d9c4206bf01721651c8efe8a173c9 100644
> --- a/drivers/mmc/host/sdhci-of-k1.c
> +++ b/drivers/mmc/host/sdhci-of-k1.c
> @@ -68,6 +68,23 @@
>  #define  SDHC_PHY_DRIVE_SEL		GENMASK(2, 0)
>  #define  SDHC_RX_BIAS_CTRL		BIT(5)
>  
> +#define SPACEMIT_SDHC_RX_CFG_REG        0x118
> +#define  SDHC_RX_SDCLK_SEL0_MASK        GENMASK(1, 0)
> +#define  SDHC_RX_SDCLK_SEL1_MASK        GENMASK(3, 2)
> +#define  SDHC_RX_SDCLK_SEL1             FIELD_PREP(SDHC_RX_SDCLK_SEL1_MASK, 1)
> +
> +#define SPACEMIT_SDHC_DLINE_CTRL_REG    0x130
> +#define  SDHC_DLINE_PU                  BIT(0)
> +#define  SDHC_RX_DLINE_CODE_MASK        GENMASK(23, 16)
> +#define  SDHC_TX_DLINE_CODE_MASK        GENMASK(31, 24)
> +
> +#define SPACEMIT_SDHC_DLINE_CFG_REG     0x134
> +#define  SDHC_RX_DLINE_REG_MASK         GENMASK(7, 0)
> +#define  SDHC_RX_DLINE_GAIN             BIT(8)
> +#define  SDHC_TX_DLINE_REG_MASK         GENMASK(23, 16)
> +
> +#define SPACEMIT_RX_DLINE_REG		9
> +
>  struct spacemit_sdhci_host {
>  	struct clk *clk_core;
>  	struct clk *clk_io;
> @@ -95,6 +112,50 @@ static inline void spacemit_sdhci_clrsetbits(struct sdhci_host *host, u32 clr, u
>  	sdhci_writel(host, val, reg);
>  }
>  
> +static void spacemit_sdhci_set_rx_delay(struct sdhci_host *host, u8 delay)
> +{
> +	spacemit_sdhci_clrsetbits(host, SDHC_RX_DLINE_CODE_MASK,
> +				  FIELD_PREP(SDHC_RX_DLINE_CODE_MASK, delay),
> +				  SPACEMIT_SDHC_DLINE_CTRL_REG);
> +}
> +
> +static void spacemit_sdhci_set_tx_delay(struct sdhci_host *host, u8 delay)
> +{
> +	spacemit_sdhci_clrsetbits(host, SDHC_TX_DLINE_CODE_MASK,
> +				  FIELD_PREP(SDHC_TX_DLINE_CODE_MASK, delay),
> +				  SPACEMIT_SDHC_DLINE_CTRL_REG);
> +}
> +
> +static void spacemit_sdhci_set_tx_dline_reg(struct sdhci_host *host, u8 dline_reg)
> +{
> +	spacemit_sdhci_clrsetbits(host, SDHC_TX_DLINE_REG_MASK,
> +				  FIELD_PREP(SDHC_TX_DLINE_REG_MASK, dline_reg),
> +				  SPACEMIT_SDHC_DLINE_CFG_REG);
> +}
> +
> +static void spacemit_sdhci_tx_tuning_prepare(struct sdhci_host *host)
> +{
> +	spacemit_sdhci_setbits(host, SDHC_TX_MUX_SEL, SPACEMIT_SDHC_TX_CFG_REG);
> +	spacemit_sdhci_setbits(host, SDHC_DLINE_PU, SPACEMIT_SDHC_DLINE_CTRL_REG);
> +	udelay(5);
> +}
> +
> +static void spacemit_sdhci_prepare_tuning(struct sdhci_host *host)
> +{
> +	spacemit_sdhci_clrsetbits(host, SDHC_RX_DLINE_REG_MASK,
> +				  FIELD_PREP(SDHC_RX_DLINE_REG_MASK, SPACEMIT_RX_DLINE_REG),
> +				  SPACEMIT_SDHC_DLINE_CFG_REG);
> +
> +	spacemit_sdhci_setbits(host, SDHC_DLINE_PU, SPACEMIT_SDHC_DLINE_CTRL_REG);
> +	udelay(5);
> +
> +	spacemit_sdhci_clrsetbits(host, SDHC_RX_SDCLK_SEL1_MASK, SDHC_RX_SDCLK_SEL1,
> +				  SPACEMIT_SDHC_RX_CFG_REG);
> +
> +	if (host->mmc->ios.timing == MMC_TIMING_MMC_HS200)
> +		spacemit_sdhci_setbits(host, SDHC_HS200_USE_RFIFO, SPACEMIT_SDHC_PHY_FUNC_REG);
> +}

Doesn't compile:

drivers/mmc/host/sdhci-of-k1.c:144:13: error: ‘spacemit_sdhci_prepare_tuning’ defined but not used [-Werror=unused-function]
  144 | static void spacemit_sdhci_prepare_tuning(struct sdhci_host *host)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/mmc/host/sdhci-of-k1.c:137:13: error: ‘spacemit_sdhci_tx_tuning_prepare’ defined but not used [-Werror=unused-function]
  137 | static void spacemit_sdhci_tx_tuning_prepare(struct sdhci_host *host)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/mmc/host/sdhci-of-k1.c:130:13: error: ‘spacemit_sdhci_set_tx_dline_reg’ defined but not used [-Werror=unused-function]
  130 | static void spacemit_sdhci_set_tx_dline_reg(struct sdhci_host *host, u8 dline_reg)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/mmc/host/sdhci-of-k1.c:123:13: error: ‘spacemit_sdhci_set_tx_delay’ defined but not used [-Werror=unused-function]
  123 | static void spacemit_sdhci_set_tx_delay(struct sdhci_host *host, u8 delay)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/mmc/host/sdhci-of-k1.c:116:13: error: ‘spacemit_sdhci_set_rx_delay’ defined but not used [-Werror=unused-function]
  116 | static void spacemit_sdhci_set_rx_delay(struct sdhci_host *host, u8 delay)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~

Squash it into the next patch I guess

> +
>  static void spacemit_sdhci_reset(struct sdhci_host *host, u8 mask)
>  {
>  	sdhci_reset(host, mask);
>