[PATCH 4.9 10/87] spi: bcm-qspi: Avoid setting MSPI_CDRAM_PCS for spi-nor master

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kamal Dasu <kdasu.kdev@gmail.com>

commit 5eb9a07a4ae1008b67d8bcd47bddb3dae97456b7 upstream.

Added fix for probing of spi-nor device non-zero chip selects. Set
MSPI_CDRAM_PCS (peripheral chip select) with spi master for MSPI
controller and not for MSPI/BSPI spi-nor master controller. Ensure
setting of cs bit in chip select register on chip select change.

Fixes: fa236a7ef24048 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi-bcm-qspi.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -543,16 +543,19 @@ static void bcm_qspi_disable_bspi(struct
 
 static void bcm_qspi_chip_select(struct bcm_qspi *qspi, int cs)
 {
-	u32 data = 0;
+	u32 rd = 0;
+	u32 wr = 0;
 
-	if (qspi->curr_cs == cs)
-		return;
 	if (qspi->base[CHIP_SELECT]) {
-		data = bcm_qspi_read(qspi, CHIP_SELECT, 0);
-		data = (data & ~0xff) | (1 << cs);
-		bcm_qspi_write(qspi, CHIP_SELECT, 0, data);
+		rd = bcm_qspi_read(qspi, CHIP_SELECT, 0);
+		wr = (rd & ~0xff) | (1 << cs);
+		if (rd == wr)
+			return;
+		bcm_qspi_write(qspi, CHIP_SELECT, 0, wr);
 		usleep_range(10, 20);
 	}
+
+	dev_dbg(&qspi->pdev->dev, "using cs:%d\n", cs);
 	qspi->curr_cs = cs;
 }
 
@@ -770,8 +773,13 @@ static int write_to_hw(struct bcm_qspi *
 			dev_dbg(&qspi->pdev->dev, "WR %04x\n", val);
 		}
 		mspi_cdram = MSPI_CDRAM_CONT_BIT;
-		mspi_cdram |= (~(1 << spi->chip_select) &
-			       MSPI_CDRAM_PCS);
+
+		if (has_bspi(qspi))
+			mspi_cdram &= ~1;
+		else
+			mspi_cdram |= (~(1 << spi->chip_select) &
+				       MSPI_CDRAM_PCS);
+
 		mspi_cdram |= ((tp.trans->bits_per_word <= 8) ? 0 :
 				MSPI_CDRAM_BITSE_BIT);