[PATCH 5/8] mci: sdhci: Add sd host v4 mode

[Jules Maselbas <jmaselbas@kalray.eu>]

Adapted from Linux commit:
8<----------------------------------------------------------------------
commit b3f80b434f7261c7ef8922f78589942d02e104f9
Author: Chunyan Zhang <zhang.chunyan@linaro.org>
Date:   Thu Aug 30 16:21:38 2018 +0800

    mmc: sdhci: Add sd host v4 mode

    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>
    Acked-by: Adrian Hunter <adrian.hunter@intel.com>
    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
8<----------------------------------------------------------------------

Signed-off-by: Jules Maselbas <jmaselbas@kalray.eu>
---
 drivers/mci/sdhci.c | 21 +++++++++++++++++++++
 drivers/mci/sdhci.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/mci/sdhci.c b/drivers/mci/sdhci.c
index a980e34314..bce4ff2a14 100644
--- a/drivers/mci/sdhci.c
+++ b/drivers/mci/sdhci.c
@@ -480,6 +480,24 @@ void sdhci_set_clock(struct sdhci *host, unsigned int clock, unsigned int input_
 	sdhci_enable_clk(host, clk);
 }
 
+static void sdhci_do_enable_v4_mode(struct sdhci *host)
+{
+	u16 ctrl2;
+
+	ctrl2 = sdhci_read16(host, SDHCI_HOST_CONTROL2);
+	if (ctrl2 & SDHCI_CTRL_V4_MODE)
+		return;
+
+	ctrl2 |= SDHCI_CTRL_V4_MODE;
+	sdhci_write16(host, SDHCI_HOST_CONTROL2, ctrl2);
+}
+
+void sdhci_enable_v4_mode(struct sdhci *host)
+{
+	host->v4_mode = true;
+	sdhci_do_enable_v4_mode(host);
+}
+
 void __sdhci_read_caps(struct sdhci *host, const u16 *ver,
 			const u32 *caps, const u32 *caps1)
 {
@@ -497,6 +515,9 @@ void __sdhci_read_caps(struct sdhci *host, const u16 *ver,
 
 	sdhci_reset(host, SDHCI_RESET_ALL);
 
+	if (host->v4_mode)
+		sdhci_do_enable_v4_mode(host);
+
 	of_property_read_u64(np, "sdhci-caps-mask", &dt_caps_mask);
 	of_property_read_u64(np, "sdhci-caps", &dt_caps);
 
diff --git a/drivers/mci/sdhci.h b/drivers/mci/sdhci.h
index 50179de0e6..1f5d0564fc 100644
--- a/drivers/mci/sdhci.h
+++ b/drivers/mci/sdhci.h
@@ -201,6 +201,7 @@ struct sdhci {
 
 	enum mci_timing timing;
 	bool preset_enabled; /* Preset is enabled */
+	bool v4_mode;		/* Host Version 4 Enable */
 
 	unsigned int quirks;
 #define SDHCI_QUIRK_MISSING_CAPS		BIT(27)
@@ -279,6 +280,7 @@ u16 sdhci_calc_clk(struct sdhci *host, unsigned int clock,
 		   unsigned int *actual_clock, unsigned int input_clock);
 void sdhci_set_clock(struct sdhci *host, unsigned int clock, unsigned int input_clock);
 void sdhci_enable_clk(struct sdhci *host, u16 clk);
+void sdhci_enable_v4_mode(struct sdhci *host);
 int sdhci_setup_host(struct sdhci *host);
 void __sdhci_read_caps(struct sdhci *host, const u16 *ver,
 			const u32 *caps, const u32 *caps1);
-- 
2.17.1