mmc: sdhci-of-at91: add support for HS400 and HS400ES

Add support for HS400 and HS400ES timings.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

Author: ehristev

drivers/mmc/host/sdhci-of-at91.c

@@ -27,6 +27,9 @@
 #define		SDMMC_MC1R_DDR		BIT(3)
 #define		SDMMC_MC1R_RSTN		BIT(6)
 #define		SDMMC_MC1R_FCD		BIT(7)
+#define SDMMC_MC3R	0x206
+#define		SDMMC_MC3R_HS400EN	BIT(0)
+#define		SDMMC_MC3R_ESMEN	BIT(1)
 #define SDMMC_CACR	0x230
 #define		SDMMC_CACR_CAPWREN	BIT(0)
 #define		SDMMC_CACR_KEY		(0x46 << 8)
@@ -103,14 +106,32 @@ static void sdhci_at91_set_clock(struct sdhci_host *host, unsigned int clock)
 static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host,
 					 unsigned int timing)
 {
-	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+	u16 clk;
+	u8 mc3r, mc1r;
+
+	mc1r = readb(host->ioaddr + SDMMC_MC1R);
+	mc3r = readb(host->ioaddr + SDMMC_MC3R);
+	clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
 	/* SDCLK must be disabled while changing the mode */
 	if (clk & SDHCI_CLOCK_CARD_EN)
 		sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
 			     SDHCI_CLOCK_CONTROL);
 
-	if (timing == MMC_TIMING_MMC_DDR52)
-		sdhci_writeb(host, SDMMC_MC1R_DDR, SDMMC_MC1R);
+	if (timing == MMC_TIMING_MMC_DDR52 || timing == MMC_TIMING_MMC_HS400)
+		mc1r |= SDMMC_MC1R_DDR;
+	else
+		mc1r &= ~SDMMC_MC1R_DDR;
+
+	sdhci_writeb(host, mc1r, SDMMC_MC1R);
+
+	if (timing == MMC_TIMING_MMC_HS400)
+		mc3r |= SDMMC_MC3R_HS400EN;
+	else
+		mc3r &= ~SDMMC_MC3R_HS400EN;
+
+	writeb(mc3r, host->ioaddr + SDMMC_MC3R);
+
 	sdhci_set_uhs_signaling(host, timing);
 
 	/* reenable SDCLK */
@@ -362,6 +383,20 @@ static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
 			   NULL)
 };
 
+static void at91_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	u8 mc3r;
+
+	mc3r = readb(host->ioaddr + SDMMC_MC3R);
+	if (ios->enhanced_strobe)
+		mc3r |= SDMMC_MC3R_ESMEN;
+	else
+		mc3r &= ~SDMMC_MC3R_ESMEN;
+
+	writeb(mc3r, host->ioaddr + SDMMC_MC3R);
+}
+
 static int sdhci_at91_probe(struct platform_device *pdev)
 {
 	const struct of_device_id	*match;
@@ -446,6 +481,8 @@ static int sdhci_at91_probe(struct platform_device *pdev)
 	if (ret)
 		goto pm_runtime_disable;
 
+	host->mmc_host_ops.hs400_enhanced_strobe = at91_sdhci_hs400_enhanced_strobe;
+
 	/*
 	 * When calling sdhci_runtime_suspend_host(), the sdhci layer makes
 	 * the assumption that all the clocks of the controller are disabled.