[PATCH v2 12/14] spi: bcm63xx-hsspi: Disable spi mem dual io

[William Zhang <william.zhang@broadcom.com>]

In general the controller supports SPI dual mode operation but the
particular SPI flash dual io read op switches from single mode in cmd
phase to dual mode in address and data phase. This is not compatible
with prepend operation where cmd and address are sent out through the
prepend buffer and they must use same the number of io pins.

This patch disables these SPI flash dual io read ops through the mem_ops
supports_op interface. This makes sure the SPI flash driver selects the
compatible read ops at run time.

Signed-off-by: William Zhang <william.zhang@broadcom.com>

---

Changes in v2:
- Remove the code that uses the deprecated flag use_cs_workaround
- Always disable dual io read ops as prepend is the default mode

 drivers/spi/spi-bcm63xx-hsspi.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/spi/spi-bcm63xx-hsspi.c b/drivers/spi/spi-bcm63xx-hsspi.c
index 2a0bef943967..dd320fda7611 100644
--- a/drivers/spi/spi-bcm63xx-hsspi.c
+++ b/drivers/spi/spi-bcm63xx-hsspi.c
@@ -20,6 +20,7 @@
 #include <linux/spi/spi.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/spi/spi-mem.h>
 #include <linux/reset.h>
 #include <linux/pm_runtime.h>
 
@@ -663,6 +664,23 @@ static int bcm63xx_hsspi_transfer_one(struct spi_master *master,
 	return 0;
 }
 
+static bool bcm63xx_hsspi_mem_supports_op(struct spi_mem *mem,
+			    const struct spi_mem_op *op)
+{
+	if (!spi_mem_default_supports_op(mem, op))
+		return false;
+
+	/* Controller doesn't support spi mem dual/quad read cmd in prepend mode */
+	if ((op->cmd.opcode == 0xbb) || (op->cmd.opcode == 0xeb))
+		return false;
+
+	return true;
+}
+
+static const struct spi_controller_mem_ops bcm63xx_hsspi_mem_ops = {
+	.supports_op = bcm63xx_hsspi_mem_supports_op,
+};
+
 static irqreturn_t bcm63xx_hsspi_interrupt(int irq, void *dev_id)
 {
 	struct bcm63xx_hsspi *bs = (struct bcm63xx_hsspi *)dev_id;
@@ -760,6 +778,7 @@ static int bcm63xx_hsspi_probe(struct platform_device *pdev)
 	mutex_init(&bs->msg_mutex);
 	init_completion(&bs->done);
 
+	master->mem_ops = &bcm63xx_hsspi_mem_ops;
 	master->dev.of_node = dev->of_node;
 	if (!dev->of_node)
 		master->bus_num = HSSPI_BUS_NUM;
-- 
2.37.3