mmc: sdhci-omap: Add card_busy host ops

Add card_busy host ops in sdhci_omap to check card busy status.

The voltage switching sequence for AM572x platform is mentioned
in Figure 25-48. eMMC/SD/SDIO Power Switching Procedure of
AM572x Sitara Processors Silicon Revision 2.0, 1.1 TRM
(SPRUHZ6I - October 2014–Revised April 2017 [1]).

In the voltage switching sequence, CLKEXTFREE bit in MMCHS_CON
should also be set after switching to 1.8v which is also taken
care in the card_busy ops.

[1] -> http://www.ti.com/lit/ug/spruhz6i/spruhz6i.pdf

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-omap.c

@@ -31,11 +31,17 @@
 #define SDHCI_OMAP_CON		0x12c
 #define CON_DW8			BIT(5)
 #define CON_DMA_MASTER		BIT(20)
+#define CON_CLKEXTFREE		BIT(16)
+#define CON_PADEN		BIT(15)
 #define CON_INIT		BIT(1)
 #define CON_OD			BIT(0)
 
 #define SDHCI_OMAP_CMD		0x20c
 
+#define SDHCI_OMAP_PSTATE	0x0224
+#define PSTATE_DLEV_DAT0	BIT(20)
+#define PSTATE_DATI		BIT(1)
+
 #define SDHCI_OMAP_HCTL		0x228
 #define HCTL_SDBP		BIT(8)
 #define HCTL_SDVS_SHIFT		9
@@ -191,6 +197,51 @@ static void sdhci_omap_conf_bus_power(struct sdhci_omap_host *omap_host,
 	}
 }
 
+static int sdhci_omap_card_busy(struct mmc_host *mmc)
+{
+	u32 reg, ac12;
+	int ret = false;
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_pltfm_host *pltfm_host;
+	struct sdhci_omap_host *omap_host;
+	u32 ier = host->ier;
+
+	pltfm_host = sdhci_priv(host);
+	omap_host = sdhci_pltfm_priv(pltfm_host);
+
+	reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_CON);
+	ac12 = sdhci_omap_readl(omap_host, SDHCI_OMAP_AC12);
+	reg &= ~CON_CLKEXTFREE;
+	if (ac12 & AC12_V1V8_SIGEN)
+		reg |= CON_CLKEXTFREE;
+	reg |= CON_PADEN;
+	sdhci_omap_writel(omap_host, SDHCI_OMAP_CON, reg);
+
+	disable_irq(host->irq);
+	ier |= SDHCI_INT_CARD_INT;
+	sdhci_writel(host, ier, SDHCI_INT_ENABLE);
+	sdhci_writel(host, ier, SDHCI_SIGNAL_ENABLE);
+
+	/*
+	 * Delay is required for PSTATE to correctly reflect
+	 * DLEV/CLEV values after PADEN is set.
+	 */
+	usleep_range(50, 100);
+	reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_PSTATE);
+	if ((reg & PSTATE_DATI) || !(reg & PSTATE_DLEV_DAT0))
+		ret = true;
+
+	reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_CON);
+	reg &= ~(CON_CLKEXTFREE | CON_PADEN);
+	sdhci_omap_writel(omap_host, SDHCI_OMAP_CON, reg);
+
+	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
+	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
+	enable_irq(host->irq);
+
+	return ret;
+}
+
 static int sdhci_omap_start_signal_voltage_switch(struct mmc_host *mmc,
 						  struct mmc_ios *ios)
 {
@@ -562,6 +613,7 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 	host->mmc_host_ops.start_signal_voltage_switch =
 					sdhci_omap_start_signal_voltage_switch;
 	host->mmc_host_ops.set_ios = sdhci_omap_set_ios;
+	host->mmc_host_ops.card_busy = sdhci_omap_card_busy;
 
 	sdhci_read_caps(host);
 	host->caps |= SDHCI_CAN_DO_ADMA2;