[PATCH V4 1/7] mmc: sdhci: add sd host v4 mode

[Chunyan Zhang <zhang.chunyan@linaro.org>]

For SD host controller version 4.00 or later ones, there're two
modes of implementation - Version 3.00 compatible mode or
Version 4 mode.  This patch introduced an interface to enable
v4 mode.

Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
---
 drivers/mmc/host/sdhci.c | 28 ++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci.h |  5 +++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 1c828e0..cab5350 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -123,6 +123,30 @@ EXPORT_SYMBOL_GPL(sdhci_dumpregs);
  *                                                                           *
 \*****************************************************************************/
 
+static void sdhci_do_enable_v4_mode(struct sdhci_host *host)
+{
+	u16 ctrl2;
+
+	ctrl2 = sdhci_readb(host, SDHCI_HOST_CONTROL2);
+	if (ctrl2 & SDHCI_CTRL_V4_MODE)
+		return;
+
+	ctrl2 |= SDHCI_CTRL_V4_MODE;
+	sdhci_writeb(host, ctrl2, SDHCI_HOST_CONTROL);
+}
+
+/*
+ * Vendor's Host Controller which supports v4 mode can call
+ * this function to enable v4 mode before calling
+ * __sdhci_add_host().
+ */
+void sdhci_enable_v4_mode(struct sdhci_host *host)
+{
+	host->v4_mode = true;
+	sdhci_do_enable_v4_mode(host);
+}
+EXPORT_SYMBOL_GPL(sdhci_enable_v4_mode);
+
 static inline bool sdhci_data_line_cmd(struct mmc_command *cmd)
 {
 	return cmd->data || cmd->flags & MMC_RSP_BUSY;
@@ -224,6 +248,10 @@ static void sdhci_do_reset(struct sdhci_host *host, u8 mask)
 
 		/* Resetting the controller clears many */
 		host->preset_enabled = false;
+
+		if (host->v4_mode)
+			sdhci_do_enable_v4_mode(host);
+
 	}
 }
 
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 23966f8..519d939 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -184,6 +184,7 @@
 #define   SDHCI_CTRL_DRV_TYPE_D		0x0030
 #define  SDHCI_CTRL_EXEC_TUNING		0x0040
 #define  SDHCI_CTRL_TUNED_CLK		0x0080
+#define  SDHCI_CTRL_V4_MODE		0x1000
 #define  SDHCI_CTRL_PRESET_VAL_ENABLE	0x8000
 
 #define SDHCI_CAPABILITIES	0x40
@@ -565,6 +566,9 @@ struct sdhci_host {
 
 	u64			data_timeout;
 
+	/* Host Version 4 Enable */
+	bool			v4_mode;
+
 	unsigned long private[0] ____cacheline_aligned;
 };
 
@@ -747,5 +751,6 @@ bool sdhci_cqe_irq(struct sdhci_host *host, u32 intmask, int *cmd_error,
 		   int *data_error);
 
 void sdhci_dumpregs(struct sdhci_host *host);
+void sdhci_enable_v4_mode(struct sdhci_host *host);
 
 #endif /* __SDHCI_HW_H */
-- 
2.7.4