On 6/03/23 06:07, Brad Larson wrote:
> Add support for mmc hardware reset using a reset-controller
> that would need to be enabled in the device tree with
> a supporting driver. The default is disabled for all
> existing designs.
>
> Signed-off-by: Brad Larson <blarson@xxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>
> v9 changes:
> - Previously patch 17/17
> - Changed delay after reset_control_assert() from 9 to 3 usec
> - Renamed sdhci_mmc_hw_reset() to sdhci_cdns_mmc_hw_reset()
>
> ---
> drivers/mmc/host/sdhci-cadence.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> index 31c77d32aa7d..d13081da5e30 100644
> --- a/drivers/mmc/host/sdhci-cadence.c
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -12,6 +12,7 @@
> #include <linux/mmc/mmc.h>
> #include <linux/of.h>
> #include <linux/of_device.h>
> +#include <linux/reset.h>
>
> #include "sdhci-pltfm.h"
>
> @@ -70,6 +71,7 @@ struct sdhci_cdns_priv {
> spinlock_t wrlock; /* write lock */
> bool enhanced_strobe;
> void (*priv_writel)(struct sdhci_cdns_priv *priv, u32 val, void __iomem *reg);
> + struct reset_control *rst_hw;
> unsigned int nr_phy_params;
> struct sdhci_cdns_phy_param phy_params[];
> };
> @@ -460,6 +462,22 @@ static void sdhci_cdns_hs400_enhanced_strobe(struct mmc_host *mmc,
> SDHCI_CDNS_HRS06_MODE_MMC_HS400);
> }
>
> +static void sdhci_cdns_mmc_hw_reset(struct mmc_host *mmc)
> +{
> + struct sdhci_host *host = mmc_priv(mmc);
> + struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
> +
> + dev_dbg(mmc_dev(host->mmc), "emmc hardware reset\n");
> +
> + reset_control_assert(priv->rst_hw);
> + /* For eMMC, minimum is 1us but give it 3us for good measure */
> + udelay(3);
> +
> + reset_control_deassert(priv->rst_hw);
> + /* For eMMC, minimum is 200us but give it 300us for good measure */
> + usleep_range(300, 1000);
> +}
> +
> static int sdhci_cdns_probe(struct platform_device *pdev)
> {
> struct sdhci_host *host;
> @@ -523,6 +541,15 @@ static int sdhci_cdns_probe(struct platform_device *pdev)
> if (ret)
> goto free;
>
> + if (host->mmc->caps & MMC_CAP_HW_RESET) {
> + priv->rst_hw = devm_reset_control_get_optional_exclusive(dev, "hw");
> + if (IS_ERR(priv->rst_hw))
> + return dev_err_probe(mmc_dev(host->mmc), PTR_ERR(priv->rst_hw),
> + "reset controller error\n");
> + if (priv->rst_hw)
> + host->mmc_host_ops.card_hw_reset = sdhci_cdns_mmc_hw_reset;
> + }
> +
> ret = sdhci_add_host(host);
> if (ret)
> goto free;
