openwrt/target/linux/octeontx/patches-5.4/0003-can-mcp251x-convert-to-half-duplex-SPI.patch

From 6edfb172ff1dd3cfc84c19790c245a4005474bb7 Mon Sep 17 00:00:00 2001
From: Tim Harvey <tharvey@gateworks.com>
Date: Tue, 25 Feb 2020 12:01:36 -0800
Subject: [PATCH 03/12] can: mcp251x: convert to half-duplex SPI

Some SPI host controllers such as the Cavium Thunder do not support
full-duplex SPI. Using half-duplex transfers allows the driver to work
with those host controllers.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
 drivers/net/can/spi/mcp251x.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
index 0b0dd3f0..c655b29 100644
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -345,8 +345,7 @@ static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
 	priv->spi_tx_buf[0] = INSTRUCTION_READ;
 	priv->spi_tx_buf[1] = reg;
 
-	mcp251x_spi_trans(spi, 3);
-	val = priv->spi_rx_buf[2];
+	spi_write_then_read(spi, priv->spi_tx_buf, 2, &val, 1);
 
 	return val;
 }
@@ -354,15 +353,16 @@ static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
 static void mcp251x_read_2regs(struct spi_device *spi, uint8_t reg,
 		uint8_t *v1, uint8_t *v2)
 {
+	u8 val[4] = {0};
 	struct mcp251x_priv *priv = spi_get_drvdata(spi);
 
 	priv->spi_tx_buf[0] = INSTRUCTION_READ;
 	priv->spi_tx_buf[1] = reg;
 
-	mcp251x_spi_trans(spi, 4);
+	spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2);
 
-	*v1 = priv->spi_rx_buf[2];
-	*v2 = priv->spi_rx_buf[3];
+	*v1 = val[0];
+	*v2 = val[1];
 }
 
 static void mcp251x_write_reg(struct spi_device *spi, u8 reg, uint8_t val)
-- 
2.7.4