Re: [PATCH v2 9/9] mmc: sdhci-cadence: add Altera Agilex5 SD6HC support

On 27/06/2026 23:14, Tanmay Kathpalia wrote:
> The Altera Agilex5 SoC integrates a Cadence SD6HC controller that needs
> platform-specific configuration to operate correctly.
> 
> The SoC requires three named resets: "sdhc-reset" and "sdmmc-ocp" are
> exclusive and must be asserted together before being released, so both
> clock domains cross the reset boundary simultaneously. "combophy" is
> shared with NAND and must only be deasserted, not toggled.
> 
> The IOMMU maps DMA addresses within a 40-bit physical address space, so
> the DMA mask is capped at 40 bits to prevent allocation beyond the
> controller's reach.
> 
> The silicon requires the MULTIBLOCK_READ_ACMD12, CAP_CLOCK_BASE_BROKEN,
> PRESET_VALUE_BROKEN, and ACMD23_BROKEN quirks. Since
> CAP_CLOCK_BASE_BROKEN prevents reading the base clock from the
> capabilities register, the maximum clock is supplied from the platform
> clock instead.
> 
> Signed-off-by: Tanmay Kathpalia <[email protected]>
> ---
>  drivers/mmc/host/sdhci-cadence-core.c | 112 ++++++++++++++++++++++++++
>  1 file changed, 112 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-cadence-core.c b/drivers/mmc/host/sdhci-cadence-core.c
> index 5b8a83c9a0aa..0f9b9dd2d2c4 100644
> --- a/drivers/mmc/host/sdhci-cadence-core.c
> +++ b/drivers/mmc/host/sdhci-cadence-core.c
> @@ -7,6 +7,7 @@
>  
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/module.h>
>  
>  #include "sdhci-cadence.h"
> @@ -84,6 +85,7 @@ struct sdhci_cdns4_phy_cfg {
>  struct sdhci_cdns_drv_data {
>  	int (*init)(struct platform_device *pdev);
>  	const struct sdhci_pltfm_data pltfm_data;
> +	u64 dma_mask;
>  };
>  
>  static const struct sdhci_cdns4_phy_cfg sdhci_cdns4_phy_cfgs[] = {
> @@ -193,6 +195,29 @@ static unsigned int sdhci_cdns_get_timeout_clock(struct sdhci_host *host)
>  	return host->max_clk;
>  }
>  
> +/**
> + * sdhci_cdns_set_dma_mask - Set platform-specific DMA mask
> + * @host: SDHCI host controller
> + *
> + * Limit DMA addresses to the physical range the controller can reach.
> + */
> +static int sdhci_cdns_set_dma_mask(struct sdhci_host *host)
> +{
> +	const struct sdhci_cdns_drv_data *data;
> +	struct device *dev = mmc_dev(host->mmc);
> +	int ret;
> +
> +	data = of_device_get_match_data(dev);
> +	if (!data || !data->dma_mask)
> +		return 0;
> +
> +	ret = dma_set_mask_and_coherent(dev, data->dma_mask);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to set DMA mask\n");
> +
> +	return 0;
> +}
> +
>  static void sdhci_cdns_set_emmc_mode(struct sdhci_cdns_priv *priv, u32 mode)
>  {
>  	u32 tmp;
> @@ -460,6 +485,65 @@ static int elba_drv_init(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static int sdhci_cdns6_agilex5_init(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct reset_control *rst_sdhc;
> +	struct reset_control *rst_ocp;
> +	struct reset_control *rst_combophy;
> +	int ret;
> +
> +	/*
> +	 * The combo PHY reset is shared with other peripheral (NAND).
> +	 * Use the _deasserted variant so devres calls assert + put on driver
> +	 * detach, keeping the shared deassert reference count balanced across
> +	 * probe/unbind cycles.
> +	 */
> +	rst_combophy = devm_reset_control_get_shared_deasserted(dev, "combophy");
> +	if (IS_ERR(rst_combophy))
> +		return dev_err_probe(dev, PTR_ERR(rst_combophy),
> +				     "failed to get combophy reset\n");

Please don't wrap lines that fit in 100 columns.  Same for two below.

> +
> +	/*
> +	 * Assert SDHCI core and SDMMC OCP/AXI bus resets together so their
> +	 * active periods overlap before both clock domains are released.
> +	 */
> +	rst_sdhc = devm_reset_control_get_exclusive(dev, "sdhc-reset");
> +	if (IS_ERR(rst_sdhc))
> +		return dev_err_probe(dev, PTR_ERR(rst_sdhc),
> +				     "failed to get sdhc-reset\n");
> +
> +	rst_ocp = devm_reset_control_get_exclusive(dev, "sdmmc-ocp");
> +	if (IS_ERR(rst_ocp))
> +		return dev_err_probe(dev, PTR_ERR(rst_ocp),
> +				     "failed to get sdmmc-ocp reset\n");
> +
> +	ret = reset_control_assert(rst_sdhc);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to assert sdhc-reset\n");
> +
> +	ret = reset_control_assert(rst_ocp);
> +	if (ret) {
> +		reset_control_deassert(rst_sdhc);
> +		return dev_err_probe(dev, ret, "failed to assert sdmmc-ocp reset\n");
> +	}
> +
> +	/* Hold resets asserted long enough for all clock domains to capture. */
> +	usleep_range(10, 20);
> +
> +	ret = reset_control_deassert(rst_sdhc);
> +	if (ret) {
> +		reset_control_deassert(rst_ocp);
> +		return dev_err_probe(dev, ret, "failed to deassert sdhc-reset\n");
> +	}
> +
> +	ret = reset_control_deassert(rst_ocp);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to deassert sdmmc-ocp reset\n");
> +
> +	return 0;
> +}
> +
>  static const struct sdhci_ops sdhci_cdns4_ops = {
>  	.set_clock = sdhci_set_clock,
>  	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
> @@ -479,6 +563,18 @@ static const struct sdhci_ops sdhci_cdns6_ops = {
>  	.hw_reset = sdhci_cdns6_hw_reset,
>  };
>  
> +static const struct sdhci_ops sdhci_cdns6_agilex5_ops = {
> +	.set_clock = sdhci_set_clock,
> +	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
> +	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
> +	.set_bus_width = sdhci_set_bus_width,
> +	.reset = sdhci_reset,
> +	.platform_execute_tuning = sdhci_cdns_execute_tuning,
> +	.set_uhs_signaling = sdhci_cdns_set_uhs_signaling,
> +	.hw_reset = sdhci_cdns6_hw_reset,
> +	.set_dma_mask = sdhci_cdns_set_dma_mask,
> +};
> +
>  static const struct sdhci_cdns_drv_data sdhci_cdns_uniphier_drv_data = {
>  	.pltfm_data = {
>  		.ops = &sdhci_cdns4_ops,
> @@ -506,6 +602,18 @@ static const struct sdhci_cdns_drv_data sdhci_cdns4_drv_data = {
>  	},
>  };
>  
> +static const struct sdhci_cdns_drv_data sdhci_cdns6_agilex5_drv_data = {
> +	.init = sdhci_cdns6_agilex5_init,
> +	.pltfm_data = {
> +		.ops = &sdhci_cdns6_agilex5_ops,
> +		.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
> +			  SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12,
> +		.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
> +			   SDHCI_QUIRK2_ACMD23_BROKEN,
> +	},
> +	.dma_mask = DMA_BIT_MASK(40),
> +};
> +
>  static const struct sdhci_cdns_drv_data sdhci_cdns6_drv_data = {
>  	.pltfm_data = {
>  		.ops = &sdhci_cdns6_ops,
> @@ -704,6 +812,10 @@ static const struct of_device_id sdhci_cdns_match[] = {
>  		.compatible = "cdns,sd4hc",
>  		.data = &sdhci_cdns4_drv_data,
>  	},
> +	{
> +		.compatible = "altr,agilex5-sd6hc",
> +		.data = &sdhci_cdns6_agilex5_drv_data,
> +	},
>  	{
>  		.compatible = "cdns,sd6hc",
>  		.data = &sdhci_cdns6_drv_data,