Commit e0e25001 authored by Tim Harvey's avatar Tim Harvey Committed by Marc Kleine-Budde
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can: mcp251x: add support for half duplex controllers 



Some SPI host controllers do not support full-duplex SPI and are
marked as such via the SPI_CONTROLLER_HALF_DUPLEX controller flag.

For such controllers use half duplex transactions but retain full
duplex transactions for the controllers that can handle those.

Signed-off-by: default avatarTim Harvey <tharvey@gateworks.com>
Link: https://lore.kernel.org/r/1595516275-1179-1-git-send-email-tharvey@gateworks.com


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 74fa565b

drivers/net/can/spi/mcp251x.c

+27 −7
Original line number Diff line number Diff line
@@ -322,8 +322,12 @@ static u8 mcp251x_read_reg(struct spi_device *spi, u8 reg) 
	priv->spi_tx_buf[0] = INSTRUCTION_READ;

	priv->spi_tx_buf[1] = reg;



	if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {

		spi_write_then_read(spi, priv->spi_tx_buf, 2, &val, 1);

	} else {

		mcp251x_spi_trans(spi, 3);

		val = priv->spi_rx_buf[2];

	}



	return val;

}
@@ -335,11 +339,19 @@ static void mcp251x_read_2regs(struct spi_device *spi, u8 reg, u8 *v1, u8 *v2) 
	priv->spi_tx_buf[0] = INSTRUCTION_READ;

	priv->spi_tx_buf[1] = reg;



	if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {

		u8 val[2] = { 0 };



		spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2);

		*v1 = val[0];

		*v2 = val[1];

	} else {

		mcp251x_spi_trans(spi, 4);



		*v1 = priv->spi_rx_buf[2];

		*v2 = priv->spi_rx_buf[3];

	}

}



static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val)

{
@@ -657,10 +669,18 @@ static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf, 
			buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);

	} else {

		priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);

		if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {

			spi_write_then_read(spi, priv->spi_tx_buf, 1,

					    priv->spi_rx_buf,

					    SPI_TRANSFER_BUF_LEN);

			memcpy(buf + 1, priv->spi_rx_buf,

			       SPI_TRANSFER_BUF_LEN - 1);

		} else {

			mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);

			memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);

		}

	}

}



static void mcp251x_hw_rx(struct spi_device *spi, int buf_idx)

{