[PATCH 3/3] tty: serial: fsl_lpuart: Add support for RS-485
From: Jakub Kiciński <hidden>
Date: 2015-05-29 10:18:28
Also in:
linux-devicetree, linux-serial, lkml
On Fri, 29 May 2015 13:35:54 +0530, Bhuvanchandra DV wrote:
quoted hunk ↗ jump to hunk
Enable Vybrid's build-in support for RS-485 auto RTS for controlling line direction of RS-485 transceiver driver. Signed-off-by: Bhuvanchandra DV <redacted> --- drivers/tty/serial/fsl_lpuart.c | 60 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+)diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 357f623..c553b14 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c@@ -820,6 +820,50 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port) TIOCSER_TEMT : 0; } +static int lpuart_config_rs485(struct uart_port *port, + struct serial_rs485 *rs485) +{ + struct lpuart_port *sport = container_of(port, + struct lpuart_port, port); + u8 modem = readb(sport->port.membase + UARTMODEM) & + ~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
Please put empty line between variables and code.
+ writeb(modem, sport->port.membase + UARTMODEM);
+
+ if (rs485->flags & SER_RS485_ENABLED) {
+ /* Enable auto RS-485 RTS mode */
+ modem |= UARTMODEM_TXRTSE;
+
+ /*
+ * RTS needs to be logic HIGH either during transer _or_ after
+ * transfer, other variants are not supported by the hardware.
+ */Indentation is off here. '*' should be aligned.
+ if (!(rs485->flags & (SER_RS485_RTS_ON_SEND | + SER_RS485_RTS_AFTER_SEND)))
and here - things should be aligned on the containing bracket (SER_ under SER_ here).
+ rs485->flags |= SER_RS485_RTS_ON_SEND; + + if (rs485->flags & SER_RS485_RTS_ON_SEND && + rs485->flags & SER_RS485_RTS_AFTER_SEND)
and here - same bracket rule (rs485-> under rs485->)
+ rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; + + /* + * The hardware defaults to RTS logic HIGH while transfer. + * Switch polarity in case RTS shall be logic HIGH + * after transfer. + * Note: UART is assumed to be active high. + */ + if (rs485->flags & SER_RS485_RTS_ON_SEND) + modem &= ~UARTMODEM_TXRTSPOL;
UARTMODEM_TXRTSPOL was already clear when you read modem.
+ else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
+ modem |= UARTMODEM_TXRTSPOL;
+ }
+
+ /* Store the new configuration */
+ sport->port.rs485 = *rs485;
+
+ writeb(modem, sport->port.membase + UARTMODEM);
+ return 0;
+}
+
static unsigned int lpuart_get_mctrl(struct uart_port *port)
{
return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;[...]
quoted hunk ↗ jump to hunk
@@ -1802,6 +1854,14 @@ static int lpuart_probe(struct platform_device *pdev) dev_info(sport->port.dev, "DMA rx channel request failed, " "operating without rx DMA\n"); + if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time")) { + sport->port.rs485.flags |= SER_RS485_ENABLED; + sport->port.rs485.flags |= SER_RS485_RTS_ON_SEND; + writeb(UARTMODEM_TXRTSE, sport->port.membase + UARTMODEM); + } else { + sport->port.rs485.flags &= ~SER_RS485_ENABLED;
Why the need to clear the flag? sport was kzalloc'ed.