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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: Tim Harvey <tharvey@gateworks.com>
Link: https://lore.kernel.org/r/1595516275-1179-1-git-send-email-tharvey@gateworks.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Tim Harvey 2020-07-23 07:57:55 -07:00 committed by Marc Kleine-Budde
parent 74fa565b63
commit e0e25001d0
1 changed files with 27 additions and 7 deletions
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34
drivers/net/can/spi/mcp251x.c
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@ -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[0] = INSTRUCTION_READ;
priv->spi_tx_buf[1] = reg; priv->spi_tx_buf[1] = reg;
mcp251x_spi_trans(spi, 3); if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {
val = priv->spi_rx_buf[2]; 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; 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[0] = INSTRUCTION_READ;
priv->spi_tx_buf[1] = reg; 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]; spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2);
*v2 = priv->spi_rx_buf[3]; *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) 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); buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
} else { } else {
priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx); priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN); if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {
memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN); 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);
}
} }
} }