[U-Boot] [PATCH] mmc: stm32_sdmmc2: update pwron management

[Patrice Chotard]

From: Patrick Delaunay <patrick.delaunay at st.com>

Correctly manage the SDMMC reset and card cycle power
to fully handle the power cycle added in the MMC uclass
and avoid issue with level-shifter with some uSDCARD.

3 states managed in driver:
  1/ reset: SDMMC disable, signal HiZ
  2/ power-cycle: SDMMC disable, signals drive to 0
  3/ power-on: SDMMC enabled

Signed-off-by: Patrick Delaunay <patrick.delaunay at st.com>
Signed-off-by: Patrice Chotard <patrice.chotard at st.com>
---

 drivers/mmc/stm32_sdmmc2.c | 78 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 67 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/stm32_sdmmc2.c b/drivers/mmc/stm32_sdmmc2.c
index e8292c438d9f..a36612dd937e 100644
--- a/drivers/mmc/stm32_sdmmc2.c
+++ b/drivers/mmc/stm32_sdmmc2.c
@@ -56,7 +56,10 @@ struct stm32_sdmmc2_ctx {
 #define SDMMC_IDMABASE0		0x58	/* SDMMC DMA buffer 0 base address */
 
 /* SDMMC_POWER register */
-#define SDMMC_POWER_PWRCTRL		GENMASK(1, 0)
+#define SDMMC_POWER_PWRCTRL_MASK	GENMASK(1, 0)
+#define SDMMC_POWER_PWRCTRL_OFF		0
+#define SDMMC_POWER_PWRCTRL_CYCLE	2
+#define SDMMC_POWER_PWRCTRL_ON		3
 #define SDMMC_POWER_VSWITCH		BIT(2)
 #define SDMMC_POWER_VSWITCHEN		BIT(3)
 #define SDMMC_POWER_DIRPOL		BIT(4)
@@ -440,23 +443,74 @@ retry_cmd:
 	return ret;
 }
 
-static void stm32_sdmmc2_pwron(struct stm32_sdmmc2_priv *priv)
+/*
+ * Reset the SDMMC with the RCC.SDMMCxRST register bit.
+ * This will reset the SDMMC to the reset state and the CPSM and DPSM
+ * to the Idle state. SDMMC is disabled, Signals Hiz.
+ */
+static void stm32_sdmmc2_reset(struct stm32_sdmmc2_priv *priv)
 {
 	/* Reset */
 	reset_assert(&priv->reset_ctl);
 	udelay(2);
 	reset_deassert(&priv->reset_ctl);
 
-	udelay(1000);
+	/* init the needed SDMMC register after reset */
+	writel(priv->pwr_reg_msk, priv->base + SDMMC_POWER);
+}
+
+/*
+ * Set the SDMMC in power-cycle state.
+ * This will make that the SDMMC_D[7:0],
+ * SDMMC_CMD and SDMMC_CK are driven low, to prevent the card from being
+ * supplied through the signal lines.
+ */
+static void stm32_sdmmc2_pwrcycle(struct stm32_sdmmc2_priv *priv)
+{
+	if ((readl(priv->base + SDMMC_POWER) & SDMMC_POWER_PWRCTRL_MASK) ==
+	    SDMMC_POWER_PWRCTRL_CYCLE)
+		return;
 
-	/* Set Power State to ON */
-	writel(SDMMC_POWER_PWRCTRL | priv->pwr_reg_msk, priv->base + SDMMC_POWER);
+	stm32_sdmmc2_reset(priv);
+	writel(SDMMC_POWER_PWRCTRL_CYCLE | priv->pwr_reg_msk,
+	       priv->base + SDMMC_POWER);
+}
+
+/*
+ * set the SDMMC state Power-on: the card is clocked
+ * manage the SDMMC state control:
+ * Reset => Power-Cycle => Power-Off => Power
+ *    PWRCTRL=10     PWCTRL=00    PWCTRL=11
+ */
+static void stm32_sdmmc2_pwron(struct stm32_sdmmc2_priv *priv)
+{
+	u32 pwrctrl =
+		readl(priv->base + SDMMC_POWER) &  SDMMC_POWER_PWRCTRL_MASK;
+
+	if (pwrctrl == SDMMC_POWER_PWRCTRL_ON)
+		return;
+
+	/* warning: same PWRCTRL value after reset and for power-off state
+	 * it is the reset state here = the only managed by the driver
+	 */
+	if (pwrctrl == SDMMC_POWER_PWRCTRL_OFF) {
+		writel(SDMMC_POWER_PWRCTRL_CYCLE | priv->pwr_reg_msk,
+		       priv->base + SDMMC_POWER);
+	}
 
 	/*
-	 * 1ms: required power up waiting time before starting the
-	 * SD initialization sequence
+	 * the remaining case is SDMMC_POWER_PWRCTRL_CYCLE
+	 * switch to Power-Off state: SDMCC disable, signals drive 1
 	 */
-	udelay(1000);
+	writel(SDMMC_POWER_PWRCTRL_OFF | priv->pwr_reg_msk,
+	       priv->base + SDMMC_POWER);
+
+	/* After the 1ms delay set the SDMMC to power-on */
+	mdelay(1);
+	writel(SDMMC_POWER_PWRCTRL_ON | priv->pwr_reg_msk,
+	       priv->base + SDMMC_POWER);
+
+	/* during the first 74 SDMMC_CK cycles the SDMMC is still disabled. */
 }
 
 #define IS_RISING_EDGE(reg) (reg & SDMMC_CLKCR_NEGEDGE ? 0 : 1)
@@ -464,8 +518,6 @@ static int stm32_sdmmc2_set_ios(struct udevice *dev)
 {
 	struct mmc *mmc = mmc_get_mmc_dev(dev);
 	struct stm32_sdmmc2_priv *priv = dev_get_priv(dev);
-	struct stm32_sdmmc2_plat *plat = dev_get_platdata(dev);
-	struct mmc_config *cfg = &plat->cfg;
 	u32 desired = mmc->clock;
 	u32 sys_clock = clk_get_rate(&priv->clk);
 	u32 clk = 0;
@@ -473,7 +525,9 @@ static int stm32_sdmmc2_set_ios(struct udevice *dev)
 	debug("%s: bus_with = %d, clock = %d\n", __func__,
 	      mmc->bus_width, mmc->clock);
 
-	if ((mmc->bus_width == 1) && (desired == cfg->f_min))
+	if (mmc->clk_disable)
+		stm32_sdmmc2_pwrcycle(priv);
+	else
 		stm32_sdmmc2_pwron(priv);
 
 	/*
@@ -577,6 +631,8 @@ static int stm32_sdmmc2_probe(struct udevice *dev)
 
 	upriv->mmc = &plat->mmc;
 
+	/* SDMMC init */
+	stm32_sdmmc2_reset(priv);
 	return 0;
 
 clk_disable:
-- 
1.9.1