rockchip: sdhci: Add HS400 Enhanced Strobe support for RK3568

On RK3568, a register bit must be set to enable Enhanced Strobe.
However, it appears that the address of this register may differ from
vendor to vendor and should be read from the underlying MMC IP. Let the
Rockchip SDHCI driver read this address and set the relevant bit when
Enhanced Strobe configuration is requested.

The IP uses a custom mode select value (0x7) for HS400, use that instead
of the common but non-standard SDHCI_CTRL_HS400 value (0x5). Also add
some necessary DLL_STRBIN and DLL_TXCLK configuration for HS400.

Additionally, a bit signifying that the connected hardware is an eMMC
chip must be set to enable Data Strobe for HS400 and HS400ES modes. Also
make the driver set this bit as appropriate.

This is partly ported from Linux's Synopsys DWC MSHC driver which
happens to be the underlying IP. (drivers/mmc/host/sdhci-of-dwcmshc.c in
Linux tree).

Co-developed-by: Yifeng Zhao <yifeng.zhao@rock-chips.com>
Signed-off-by: Yifeng Zhao <yifeng.zhao@rock-chips.com>
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

drivers/mmc/rockchip_sdhci.c

@@ -22,6 +22,8 @@
 #include <asm/arch-rockchip/clock.h>
 #include <asm/arch-rockchip/hardware.h>
 
+/* DWCMSHC specific Mode Select value */
+#define DWCMSHC_CTRL_HS400		0x7
 /* 400KHz is max freq for card ID etc. Use that as min */
 #define EMMC_MIN_FREQ	400000
 #define KHz	(1000)
@@ -45,6 +47,14 @@
 #define ARASAN_VENDOR_REGISTER		0x78
 #define ARASAN_VENDOR_ENHANCED_STROBE	BIT(0)
 
+/* DWC IP vendor area 1 pointer */
+#define DWCMSHC_P_VENDOR_AREA1		0xe8
+#define DWCMSHC_AREA1_MASK		GENMASK(11, 0)
+/* Offset inside the vendor area 1 */
+#define DWCMSHC_EMMC_CONTROL		0x2c
+#define DWCMSHC_CARD_IS_EMMC		BIT(0)
+#define DWCMSHC_ENHANCED_STROBE		BIT(8)
+
 /* Rockchip specific Registers */
 #define DWCMSHC_EMMC_DLL_CTRL		0x800
 #define DWCMSHC_EMMC_DLL_CTRL_RESET	BIT(1)
@@ -60,8 +70,14 @@
 #define DWCMSHC_EMMC_DLL_INC_VALUE	2
 #define DWCMSHC_EMMC_DLL_INC		8
 #define DWCMSHC_EMMC_DLL_DLYENA		BIT(27)
-#define DLL_TXCLK_TAPNUM_DEFAULT	0x10
+#define DLL_TXCLK_TAPNUM_DEFAULT	0xA
-#define DLL_STRBIN_TAPNUM_DEFAULT	0x3
+
+#define DLL_STRBIN_TAPNUM_DEFAULT	0x8
+#define DLL_STRBIN_TAPNUM_FROM_SW	BIT(24)
+#define DLL_STRBIN_DELAY_NUM_SEL	BIT(26)
+#define DLL_STRBIN_DELAY_NUM_OFFSET	16
+#define DLL_STRBIN_DELAY_NUM_DEFAULT	0x16
+
 #define DLL_TXCLK_TAPNUM_FROM_SW	BIT(24)
 #define DWCMSHC_EMMC_DLL_LOCKED		BIT(8)
 #define DWCMSHC_EMMC_DLL_TIMEOUT	BIT(9)
@@ -327,7 +343,8 @@ static int rk3568_sdhci_emmc_set_clock(struct sdhci_host *host, unsigned int clo
 		sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_TXCLK);
 
 		extra = DWCMSHC_EMMC_DLL_DLYENA |
-			DLL_STRBIN_TAPNUM_DEFAULT;
+			DLL_STRBIN_TAPNUM_DEFAULT |
+			DLL_STRBIN_TAPNUM_FROM_SW;
 		sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
 	} else {
 		/* reset the clock phase when the frequency is lower than 100MHz */
@@ -335,7 +352,15 @@ static int rk3568_sdhci_emmc_set_clock(struct sdhci_host *host, unsigned int clo
 		extra = DLL_RXCLK_NO_INVERTER << DWCMSHC_EMMC_DLL_RXCLK_SRCSEL;
 		sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_RXCLK);
 		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_TXCLK);
-		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_STRBIN);
+		/*
+		 * Before switching to hs400es mode, the driver will enable
+		 * enhanced strobe first. PHY needs to configure the parameters
+		 * of enhanced strobe first.
+		 */
+		extra = DWCMSHC_EMMC_DLL_DLYENA |
+			DLL_STRBIN_DELAY_NUM_SEL |
+			DLL_STRBIN_DELAY_NUM_DEFAULT << DLL_STRBIN_DELAY_NUM_OFFSET;
+		sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
 	}
 
 	return 0;
@@ -346,11 +371,30 @@ static int rk3568_emmc_get_phy(struct udevice *dev)
 	return 0;
 }
 
+static int rk3568_sdhci_set_enhanced_strobe(struct sdhci_host *host)
+{
+	struct mmc *mmc = host->mmc;
+	u32 vendor;
+	int reg;
+
+	reg = (sdhci_readl(host, DWCMSHC_P_VENDOR_AREA1) & DWCMSHC_AREA1_MASK)
+	      + DWCMSHC_EMMC_CONTROL;
+
+	vendor = sdhci_readl(host, reg);
+	if (mmc->selected_mode == MMC_HS_400_ES)
+		vendor |= DWCMSHC_ENHANCED_STROBE;
+	else
+		vendor &= ~DWCMSHC_ENHANCED_STROBE;
+	sdhci_writel(host, vendor, reg);
+
+	return 0;
+}
+
 static int rk3568_sdhci_set_ios_post(struct sdhci_host *host)
 {
 	struct mmc *mmc = host->mmc;
 	uint clock = mmc->tran_speed;
-	u32 reg;
+	u32 reg, vendor_reg;
 
 	if (!clock)
 		clock = mmc->clock;
@@ -360,8 +404,15 @@ static int rk3568_sdhci_set_ios_post(struct sdhci_host *host)
 	if (mmc->selected_mode == MMC_HS_400 || mmc->selected_mode == MMC_HS_400_ES) {
 		reg = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 		reg &= ~SDHCI_CTRL_UHS_MASK;
-		reg |= SDHCI_CTRL_HS400;
+		reg |= DWCMSHC_CTRL_HS400;
 		sdhci_writew(host, reg, SDHCI_HOST_CONTROL2);
+
+		vendor_reg = (sdhci_readl(host, DWCMSHC_P_VENDOR_AREA1) & DWCMSHC_AREA1_MASK)
+			     + DWCMSHC_EMMC_CONTROL;
+		/* set CARD_IS_EMMC bit to enable Data Strobe for HS400 */
+		reg = sdhci_readw(host, vendor_reg);
+		reg |= DWCMSHC_CARD_IS_EMMC;
+		sdhci_writew(host, reg, vendor_reg);
 	} else {
 		sdhci_set_uhs_timing(host);
 	}
@@ -554,6 +605,7 @@ static const struct sdhci_data rk3568_data = {
 	.get_phy = rk3568_emmc_get_phy,
 	.emmc_phy_init = rk3568_emmc_phy_init,
 	.set_ios_post = rk3568_sdhci_set_ios_post,
+	.set_enhanced_strobe = rk3568_sdhci_set_enhanced_strobe,
 };
 
 static const struct udevice_id sdhci_ids[] = {