[PATCH 3/5] mtd: brcmnand: Optional DT flag to reset IPROC NAND controller

[Anup Patel <anup.patel@broadcom.com>]

The BRCM NAND controller on NS2 SoC requires a reset to
cleanup previously configured NAND controller state.

This patch adds optional boolean device tree flag named
"brcm,nand-iproc-reset". If this flag is present in NAND
controller DT node then BRCM IPROC NAND driver will reset
the NAND controller before any commands are issued.

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Pramod KUMAR <pramodku@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
---
 drivers/mtd/nand/brcmnand/iproc_nand.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/mtd/nand/brcmnand/iproc_nand.c b/drivers/mtd/nand/brcmnand/iproc_nand.c
index 683495c..d837207 100644
--- a/drivers/mtd/nand/brcmnand/iproc_nand.c
+++ b/drivers/mtd/nand/brcmnand/iproc_nand.c
@@ -11,6 +11,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
@@ -35,6 +36,10 @@ struct iproc_nand_soc_priv {
 #define IPROC_NAND_APB_LE_MODE             BIT(24)
 #define IPROC_NAND_INT_CTRL_READ_ENABLE    BIT(6)
 
+#define IPROC_NAND_RESET_OFFSET            0x3f8
+#define IPROC_NAND_RESET_BIT_SHIFT         0
+#define IPROC_NAND_RESET_BIT               BIT(IPROC_NAND_RESET_BIT_SHIFT)
+
 static bool iproc_nand_intc_ack(struct brcmnand_soc *soc)
 {
 	struct iproc_nand_soc_priv *priv = soc->priv;
@@ -93,6 +98,7 @@ static void iproc_nand_apb_access(struct brcmnand_soc *soc, bool prepare)
 
 static int iproc_nand_probe(struct platform_device *pdev)
 {
+	u32 reset;
 	struct device *dev = &pdev->dev;
 	struct iproc_nand_soc_priv *priv;
 	struct brcmnand_soc *soc;
@@ -124,6 +130,19 @@ static int iproc_nand_probe(struct platform_device *pdev)
 	soc->ctlrdy_set_enabled = iproc_nand_intc_set;
 	soc->prepare_data_bus = iproc_nand_apb_access;
 
+	if (of_property_read_bool(dev->of_node, "brcm,nand-iproc-reset")) {
+		/* Put controller in reset and wait 10 usecs */
+		reset = readl(priv->idm_base + IPROC_NAND_RESET_OFFSET);
+		reset |= IPROC_NAND_RESET_BIT;
+		writel(reset, priv->idm_base + IPROC_NAND_RESET_OFFSET);
+		udelay(10);
+		/* Bring controller out of reset and wait 10 usecs */
+		reset = readl(priv->idm_base + IPROC_NAND_RESET_OFFSET);
+		reset &= ~IPROC_NAND_RESET_BIT;
+		writel(reset, priv->idm_base + IPROC_NAND_RESET_OFFSET);
+		udelay(10);
+	}
+
 	return brcmnand_probe(pdev, soc);
 }
 
-- 
1.9.1