[PATCH v1] mmc: sdhci-of-dwcmshc: Enable enhanced strobe for eMMC in HS400 for Rockchip

[Anand Moon <linux.amoon@gmail.com>]

As per RK3588 TRM Part 2 section EMMC_EMMC_CTRL, Add code to enable
enhanced strobe mode, set the card type to eMMC in HS400 during clock
configuration. This bit instructs Host to sample the CMD line using data
strobe for HS400 mode.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index eebd453899566..3edde4532b13c 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -77,6 +77,10 @@
 #define CV18XX_RETRY_TUNING_MAX			50
 
 /* Rockchip specific Registers */
+#define DWCMSHC_EMMC_CTRL		0x52c
+#define  EMMC_CTRL_CARD_IS_EMMC		BIT(0)
+#define  EMMC_CTRL_ENH_STROBE_ENABLE	BIT(8)
+
 #define DWCMSHC_EMMC_DLL_CTRL		0x800
 #define DWCMSHC_EMMC_DLL_RXCLK		0x804
 #define DWCMSHC_EMMC_DLL_TXCLK		0x808
@@ -660,6 +664,14 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 			DLL_CMDOUT_TAPNUM_90_DEGREES |
 			DLL_CMDOUT_TAPNUM_FROM_SW;
 		sdhci_writel(host, extra, DECMSHC_EMMC_DLL_CMDOUT);
+
+		extra = sdhci_readl(host, DWCMSHC_EMMC_CTRL);
+		if (extra & EMMC_CTRL_CARD_IS_EMMC) {
+			extra |= EMMC_CTRL_ENH_STROBE_ENABLE;
+			sdhci_writel(host, extra, DWCMSHC_EMMC_CTRL);
+		} else {
+			dev_info(mmc_dev(host->mmc), "strobe mode not enabled!\n");
+		}
 	}
 
 	extra = DWCMSHC_EMMC_DLL_DLYENA |

base-commit: 4427259cc7f7571a157fbc9b5011e1ef6fe0a4a8
-- 
2.50.1