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From:   Sowjanya Komatineni <skomatineni@nvidia.com>
To:     <thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
        <talho@nvidia.com>, <skomatineni@nvidia.com>, <broonie@kernel.org>,
        <robh+dt@kernel.org>, <mark.rutland@arm.com>,
        <kyarlagadda@nvidia.com>
CC:     <ldewangan@nvidia.com>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-spi@vger.kernel.org>,
        <devicetree@vger.kernel.org>
Subject: [PATCH V2 09/20] spi: tegra114: add 3 wire transfer mode support
Date:   Thu, 4 Apr 2019 17:14:08 -0700
Message-ID: <1554423259-26056-9-git-send-email-skomatineni@nvidia.com>
In-Reply-To: <1554423259-26056-1-git-send-email-skomatineni@nvidia.com>
References: <1554423259-26056-1-git-send-email-skomatineni@nvidia.com>
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This patch adds 3 wire transfer support to SPI mode list along with
its implementation.

3 wire or Bi-directional mode uses only one serial data pin for the
transfer. SPI in master mode uses MOSI data line only and MISO data
line is not used.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 drivers/spi/spi-tegra114.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-tegra114.c b/drivers/spi/spi-tegra114.c
index 239fb0c8c31f..212bb90aa0cb 100644
--- a/drivers/spi/spi-tegra114.c
+++ b/drivers/spi/spi-tegra114.c
@@ -755,6 +755,11 @@ static u32 tegra_spi_setup_transfer_one(struct spi_device *spi,
 		else
 			command1 &= ~SPI_LSBIT_FE;
 
+		if (spi->mode & SPI_3WIRE)
+			command1 |= SPI_BIDIROE;
+		else
+			command1 &= ~SPI_BIDIROE;
+
 		if (tspi->cs_control) {
 			if (tspi->cs_control != spi)
 				tegra_spi_writel(tspi, command1, SPI_COMMAND1);
@@ -1159,7 +1164,7 @@ static int tegra_spi_probe(struct platform_device *pdev)
 
 	/* the spi->mode bits understood by this driver: */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST |
-			    SPI_TX_DUAL | SPI_RX_DUAL;
+			    SPI_TX_DUAL | SPI_RX_DUAL | SPI_3WIRE;
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
 	master->setup = tegra_spi_setup;
 	master->transfer_one_message = tegra_spi_transfer_one_message;
-- 
2.7.4