[U-Boot] [PATCH 1/5] mmc: sunxi: add support for automatic delay calibration

[Vagrant Cascadian <vagrant@debian.org>]

From: Vasily Khoruzhick <anarsoul@gmail.com>

A64 supports automatic delay calibration and Linux driver uses it
instead of hardcoded delays. Add support for it to u-boot driver.

Fixes eMMC instability on Pinebook

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
---

 arch/arm/include/asm/arch-sunxi/mmc.h |  6 +++++-
 arch/arm/mach-sunxi/Kconfig           |  1 +
 drivers/mmc/Kconfig                   |  4 ++++
 drivers/mmc/sunxi_mmc.c               | 20 +++++++++++++++++++-
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/arch-sunxi/mmc.h b/arch/arm/include/asm/arch-sunxi/mmc.h
index d98c53faaa..f2deafddd2 100644
--- a/arch/arm/include/asm/arch-sunxi/mmc.h
+++ b/arch/arm/include/asm/arch-sunxi/mmc.h
@@ -46,7 +46,9 @@ struct sunxi_mmc {
 	u32 cbda;		/* 0x94 */
 	u32 res2[26];
 #if defined(CONFIG_SUNXI_GEN_SUN6I) || defined(CONFIG_MACH_SUN50I_H6)
-	u32 res3[64];
+	u32 res3[17];
+	u32 samp_dl;
+	u32 res4[46];
 #endif
 	u32 fifo;		/* 0x100 / 0x200 FIFO access address */
 };
@@ -130,5 +132,7 @@ struct sunxi_mmc {
 #define SUNXI_MMC_COMMON_CLK_GATE		(1 << 16)
 #define SUNXI_MMC_COMMON_RESET			(1 << 18)
 
+#define SUNXI_MMC_CAL_DL_SW_EN		(0x1 << 7)
+
 struct mmc *sunxi_mmc_init(int sdc_no);
 #endif /* _SUNXI_MMC_H */
diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
index 686f38fec4..ae77ee9e8e 100644
--- a/arch/arm/mach-sunxi/Kconfig
+++ b/arch/arm/mach-sunxi/Kconfig
@@ -271,6 +271,7 @@ config MACH_SUN50I
 	bool "sun50i (Allwinner A64)"
 	select ARM64
 	select DM_I2C
+	select MMC_SUNXI_SUPPORTS_CALIBRATION
 	select PHY_SUN4I_USB
 	select SUNXI_DE2
 	select SUNXI_GEN_SUN6I
diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 0a0d4aaf6c..fb8f6697d4 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -569,6 +569,10 @@ config MMC_SUNXI_HAS_NEW_MODE
 	bool
 	depends on MMC_SUNXI
 
+config MMC_SUNXI_SUPPORTS_CALIBRATION
+	bool
+	depends on MMC_SUNXI
+
 config GENERIC_ATMEL_MCI
 	bool "Atmel Multimedia Card Interface support"
 	depends on DM_MMC && BLK && ARCH_AT91
diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index 39f15eb423..7b064b482c 100644
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -99,11 +99,15 @@ static int mmc_set_mod_clk(struct sunxi_mmc_priv *priv, unsigned int hz)
 {
 	unsigned int pll, pll_hz, div, n, oclk_dly, sclk_dly;
 	bool new_mode = false;
+	bool calibrate = false;
 	u32 val = 0;
 
 	if (IS_ENABLED(CONFIG_MMC_SUNXI_HAS_NEW_MODE) && (priv->mmc_no == 2))
 		new_mode = true;
 
+	if (IS_ENABLED(CONFIG_MMC_SUNXI_SUPPORTS_CALIBRATION))
+		calibrate = true;
+
 	/*
 	 * The MMC clock has an extra /2 post-divider when operating in the new
 	 * mode.
@@ -174,7 +178,11 @@ static int mmc_set_mod_clk(struct sunxi_mmc_priv *priv, unsigned int hz)
 		val = CCM_MMC_CTRL_MODE_SEL_NEW;
 		setbits_le32(&priv->reg->ntsr, SUNXI_MMC_NTSR_MODE_SEL_NEW);
 #endif
-	} else {
+	} else if (!calibrate) {
+		/*
+		 * Use hardcoded delay values if controller doesn't support
+		 * calibration
+		 */
 		val = CCM_MMC_CTRL_OCLK_DLY(oclk_dly) |
 			CCM_MMC_CTRL_SCLK_DLY(sclk_dly);
 	}
@@ -228,6 +236,16 @@ static int mmc_config_clock(struct sunxi_mmc_priv *priv, struct mmc *mmc)
 	rval &= ~SUNXI_MMC_CLK_DIVIDER_MASK;
 	writel(rval, &priv->reg->clkcr);
 
+#ifdef CONFIG_MMC_SUNXI_SUPPORTS_CALIBRATION
+	/* A64 supports calibration of delays on MMC controller and we
+	 * have to set delay of zero before starting calibration.
+	 * Allwinner BSP driver sets a delay only in the case of
+	 * using HS400 which is not supported by mainline U-Boot or
+	 * Linux at the moment
+	 */
+	writel(SUNXI_MMC_CAL_DL_SW_EN, &priv->reg->samp_dl);
+#endif
+
 	/* Re-enable Clock */
 	rval |= SUNXI_MMC_CLK_ENABLE;
 	writel(rval, &priv->reg->clkcr);
-- 
2.11.0