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tty: serial: lpuart: Add RS485 support for 32-bit uart flavour 

This commits adds RS485 support for LPUART hardware that uses 32-bit
registers. These are typically found in i.MX8 processors.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Reviewed-by: Fugang Duan <fugang.duan@nxp.com>

Link: https://lore.kernel.org/r/20191017141428.10330-3-philippe.schenker@toradex.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Philippe Schenker 2019-10-17 14:14:42 +00:00 committed by Greg Kroah-Hartman
parent e3553fee81
commit 67b0183786
1 changed files with 63 additions and 2 deletions
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65
drivers/tty/serial/fsl_lpuart.c
View File

@ -1280,6 +1280,57 @@ static int lpuart_config_rs485(struct uart_port *port,
return 0;
}
static int lpuart32_config_rs485(struct uart_port *port,
struct serial_rs485 *rs485)
{
struct lpuart_port *sport = container_of(port,
struct lpuart_port, port);
unsigned long modem = lpuart32_read(&sport->port, UARTMODIR)
& ~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
lpuart32_write(&sport->port, modem, UARTMODIR);
/* clear unsupported configurations */
rs485->delay_rts_before_send = 0;
rs485->delay_rts_after_send = 0;
rs485->flags &= ~SER_RS485_RX_DURING_TX;
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.
*/
if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
SER_RS485_RTS_AFTER_SEND)))
rs485->flags |= SER_RS485_RTS_ON_SEND;
if (rs485->flags & SER_RS485_RTS_ON_SEND &&
rs485->flags & SER_RS485_RTS_AFTER_SEND)
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;
else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
modem |= UARTMODEM_TXRTSPOL;
}
/* Store the new configuration */
sport->port.rs485 = *rs485;
lpuart32_write(&sport->port, modem, UARTMODIR);
return 0;
}
static unsigned int lpuart_get_mctrl(struct uart_port *port)
{
unsigned int temp = 0;
@ -1878,6 +1929,13 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
ctrl |= UARTCTRL_M;
}
/*
* When auto RS-485 RTS mode is enabled,
* hardware flow control need to be disabled.
*/
if (sport->port.rs485.flags & SER_RS485_ENABLED)
termios->c_cflag &= ~CRTSCTS;
if (termios->c_cflag & CRTSCTS) {
modem |= (UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
} else {
@ -2405,7 +2463,10 @@ static int lpuart_probe(struct platform_device *pdev)
sport->port.ops = &lpuart_pops;
sport->port.flags = UPF_BOOT_AUTOCONF;
sport->port.rs485_config = lpuart_config_rs485;
if (lpuart_is_32(sport))
sport->port.rs485_config = lpuart32_config_rs485;
else
sport->port.rs485_config = lpuart_config_rs485;
sport->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
if (IS_ERR(sport->ipg_clk)) {
@ -2459,7 +2520,7 @@ static int lpuart_probe(struct platform_device *pdev)
sport->port.rs485.delay_rts_after_send)
dev_err(&pdev->dev, "driver doesn't support RTS delays\n");
lpuart_config_rs485(&sport->port, &sport->port.rs485);
sport->port.rs485_config(&sport->port, &sport->port.rs485);
sport->dma_tx_chan = dma_request_slave_channel(sport->port.dev, "tx");
if (!sport->dma_tx_chan)