[U-Boot] [PATCH v4] spi: fsl_qspi: Add controller busy check before new spi operation

[Suresh Gupta]

It is recommended to check either controller is free to take
new spi action. The IP_ACC and AHB_ACC bits indicates that
the controller is busy in IP or AHB mode respectively.
And the BUSY bit indicates that controller is currently
busy handling a transaction to an external flash device

Signed-off-by: Suresh Gupta <suresh.gupta at nxp.com>
---
Change in v4:
 - change Timeout from 1000ms to 100ms 


Changes in v3:
 - replace printf to debug
 - return whatever return from wait_for_bit, before it was -EBUSY

Changes in v2:

 - Add wait_for_bit instead of while
 - move the busy check code to fsl_qspi_claim_bus form qspi_xfer


 drivers/spi/fsl_qspi.c | 28 +++++++++++++++++++++++++++-
 drivers/spi/fsl_qspi.h |  4 ++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/fsl_qspi.c b/drivers/spi/fsl_qspi.c
index 1dfa89a..8753ed9 100644
--- a/drivers/spi/fsl_qspi.c
+++ b/drivers/spi/fsl_qspi.c
@@ -14,6 +14,7 @@
 #include <dm.h>
 #include <errno.h>
 #include <watchdog.h>
+#include <wait_bit.h>
 #include "fsl_qspi.h"
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -991,7 +992,7 @@ static int fsl_qspi_probe(struct udevice *bus)
 	struct fsl_qspi_platdata *plat = dev_get_platdata(bus);
 	struct fsl_qspi_priv *priv = dev_get_priv(bus);
 	struct dm_spi_bus *dm_spi_bus;
-	int i;
+	int i, ret;
 
 	dm_spi_bus = bus->uclass_priv;
 
@@ -1011,6 +1012,18 @@ static int fsl_qspi_probe(struct udevice *bus)
 	priv->flash_num = plat->flash_num;
 	priv->num_chipselect = plat->num_chipselect;
 
+	/* make sure controller is not busy anywhere */
+	ret = wait_for_bit(__func__, &priv->regs->sr,
+			   QSPI_SR_BUSY_MASK |
+			   QSPI_SR_AHB_ACC_MASK |
+			   QSPI_SR_IP_ACC_MASK,
+			   false, 100, false);
+
+	if (ret) {
+		debug("ERROR : The controller is busy\n");
+		return ret;
+	}
+
 	mcr_val = qspi_read32(priv->flags, &priv->regs->mcr);
 	qspi_write32(priv->flags, &priv->regs->mcr,
 		     QSPI_MCR_RESERVED_MASK | QSPI_MCR_MDIS_MASK |
@@ -1156,10 +1169,23 @@ static int fsl_qspi_claim_bus(struct udevice *dev)
 	struct fsl_qspi_priv *priv;
 	struct udevice *bus;
 	struct dm_spi_slave_platdata *slave_plat = dev_get_parent_platdata(dev);
+	int ret;
 
 	bus = dev->parent;
 	priv = dev_get_priv(bus);
 
+	/* make sure controller is not busy anywhere */
+	ret = wait_for_bit(__func__, &priv->regs->sr,
+			   QSPI_SR_BUSY_MASK |
+			   QSPI_SR_AHB_ACC_MASK |
+			   QSPI_SR_IP_ACC_MASK,
+			   false, 100, false);
+
+	if (ret) {
+		debug("ERROR : The controller is busy\n");
+		return ret;
+	}
+
 	priv->cur_amba_base = priv->amba_base[slave_plat->cs];
 
 	qspi_module_disable(priv, 0);
diff --git a/drivers/spi/fsl_qspi.h b/drivers/spi/fsl_qspi.h
index 6cb3610..e468eb2 100644
--- a/drivers/spi/fsl_qspi.h
+++ b/drivers/spi/fsl_qspi.h
@@ -105,6 +105,10 @@ struct fsl_qspi_regs {
 #define QSPI_RBCT_RXBRD_SHIFT		8
 #define QSPI_RBCT_RXBRD_USEIPS		(1 << QSPI_RBCT_RXBRD_SHIFT)
 
+#define QSPI_SR_AHB_ACC_SHIFT		2
+#define QSPI_SR_AHB_ACC_MASK		(1 << QSPI_SR_AHB_ACC_SHIFT)
+#define QSPI_SR_IP_ACC_SHIFT		1
+#define QSPI_SR_IP_ACC_MASK		(1 << QSPI_SR_IP_ACC_SHIFT)
 #define QSPI_SR_BUSY_SHIFT		0
 #define QSPI_SR_BUSY_MASK		(1 << QSPI_SR_BUSY_SHIFT)
 
-- 
1.9.3