From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jakub =?UTF-8?B?S2ljacWEc2tp?= Subject: Re: [PATCH 3/3] tty: serial: fsl_lpuart: Add support for RS-485 Date: Fri, 29 May 2015 12:18:08 +0200 Message-ID: <20150529121808.27346afc@north> References: <1432886754-30115-1-git-send-email-bhuvanchandra.dv@toradex.com> <1432886754-30115-4-git-send-email-bhuvanchandra.dv@toradex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1432886754-30115-4-git-send-email-bhuvanchandra.dv@toradex.com> Sender: linux-kernel-owner@vger.kernel.org To: Bhuvanchandra DV Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, stefan@agner.ch, shawn.guo@linaro.org, kernel@pengutronix.de, jslaby@suse.cz, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, bhuvanchandra.dv@gmail.com List-Id: devicetree@vger.kernel.org On Fri, 29 May 2015 13:35:54 +0530, Bhuvanchandra DV wrote: > 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 > --- > 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; [...] > @@ -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.