From: Tim Harvey <tharvey@xxxxxxxxxxxxx> 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: Tim Harvey <tharvey@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/1595516275-1179-1-git-send-email-tharvey@xxxxxxxxxxxxx Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/spi/mcp251x.c | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-) diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c index 3bf57bc9b3ff..22d814ae4edc 100644 --- a/drivers/net/can/spi/mcp251x.c +++ b/drivers/net/can/spi/mcp251x.c @@ -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; - mcp251x_spi_trans(spi, 3); - val = priv->spi_rx_buf[2]; + 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; } @@ -335,10 +339,18 @@ 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; - mcp251x_spi_trans(spi, 4); + if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) { + u8 val[2] = { 0 }; - *v1 = priv->spi_rx_buf[2]; - *v2 = priv->spi_rx_buf[3]; + 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) @@ -657,8 +669,16 @@ 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); - mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN); - memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN); + 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); + } } } -- 2.28.0
