[PATCH 5.11 174/210] can: mcp251x: fix support for half duplex SPI host controllers

Greg Kroah-Hartman
2021-04-12T09:38:03Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

[ Upstream commit 617085fca6375e2c1667d1fbfc6adc4034c85f04 ]

Some SPI host controllers do not support full-duplex SPI transfers.

The function mcp251x_spi_trans() does a full duplex transfer. It is
used in several places in the driver, where a TX half duplex transfer
is sufficient.

To fix support for half duplex SPI host controllers, this patch
introduces a new function mcp251x_spi_write() and changes all callers
that do a TX half duplex transfer to use mcp251x_spi_write().

Fixes: e0e25001d088 ("can: mcp251x: add support for half duplex controllers")
Link: https://lore.kernel.org/r/20210330100246.1074375-1-mkl@pengutronix.de
Cc: Tim Harvey <tharvey@gateworks.com>
Tested-By: Tim Harvey <tharvey@gateworks.com>
Reported-by: Gerhard Bertelsmann <info@gerhard-bertelsmann.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/spi/mcp251x.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
index 25859d16d06f..e7be36dc2159 100644
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -314,6 +314,18 @@ static int mcp251x_spi_trans(struct spi_device *spi, int len)
return ret;
}

+static int mcp251x_spi_write(struct spi_device *spi, int len)
+{
+ struct mcp251x_priv *priv = spi_get_drvdata(spi);
+ int ret;
+
+ ret = spi_write(spi, priv->spi_tx_buf, len);
+ if (ret)
+ dev_err(&spi->dev, "spi write failed: ret = %d\n", ret);
+
+ return ret;
+}
+
static u8 mcp251x_read_reg(struct spi_device *spi, u8 reg)
{
struct mcp251x_priv *priv = spi_get_drvdata(spi);
@@ -361,7 +373,7 @@ static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val)
priv->spi_tx_buf[1] = reg;
priv->spi_tx_buf[2] = val;

- mcp251x_spi_trans(spi, 3);
+ mcp251x_spi_write(spi, 3);
}

static void mcp251x_write_2regs(struct spi_device *spi, u8 reg, u8 v1, u8 v2)
@@ -373,7 +385,7 @@ static void mcp251x_write_2regs(struct spi_device *spi, u8 reg, u8 v1, u8 v2)
priv->spi_tx_buf[2] = v1;
priv->spi_tx_buf[3] = v2;

- mcp251x_spi_trans(spi, 4);
+ mcp251x_spi_write(spi, 4);
}

static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
@@ -386,7 +398,7 @@ static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
priv->spi_tx_buf[2] = mask;
priv->spi_tx_buf[3] = val;

- mcp251x_spi_trans(spi, 4);
+ mcp251x_spi_write(spi, 4);
}

static u8 mcp251x_read_stat(struct spi_device *spi)
@@ -618,7 +630,7 @@ static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf,
buf[i]);
} else {
memcpy(priv->spi_tx_buf, buf, TXBDAT_OFF + len);
- mcp251x_spi_trans(spi, TXBDAT_OFF + len);
+ mcp251x_spi_write(spi, TXBDAT_OFF + len);
}
}

@@ -650,7 +662,7 @@ static void mcp251x_hw_tx(struct spi_device *spi, struct can_frame *frame,

/* use INSTRUCTION_RTS, to avoid "repeated frame problem" */
priv->spi_tx_buf[0] = INSTRUCTION_RTS(1 << tx_buf_idx);
- mcp251x_spi_trans(priv->spi, 1);
+ mcp251x_spi_write(priv->spi, 1);
}

static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
@@ -888,7 +900,7 @@ static int mcp251x_hw_reset(struct spi_device *spi)
mdelay(MCP251X_OST_DELAY_MS);

priv->spi_tx_buf[0] = INSTRUCTION_RESET;
- ret = mcp251x_spi_trans(spi, 1);
+ ret = mcp251x_spi_write(spi, 1);
if (ret)
return ret;

--
2.30.2