On Thu, Jul 24, 2008 at 01:47:29PM +0200, Laurent Pinchart wrote: > This patch adds support for the automatic RS485 direction control feature > present in 16850 UARTs. > > A new termios c_cflag, CARTS, is introduced to configure automatic direction > control from userspace. > > This is a first proposal. I'm open to suggestions regarding the CARTS name. I think CARTS is a bad name - if you look at other 8250 ports, they have auto-flow control for normal communications which not only includes stopping the transmitter when CTS deasserts, but also allows the device to deassert RTS when the receive FIFO reaches a certain level. That means that the name "auto RTS" is confusing. Maybe a better name would be CRS485 to enable RS485 direction control? Then we can use CRTSCTS to mean "on the RTS signal". If/when a CDTRDSR for DTR/DSR flow control is introduced, we could then use that to switch to DTR RS485 direction control instead. > I assume the CARTS flag will have to be added to all asm/termbits.h > headers. Yes... > Why are the termios bits definitions platform specific ? ... though if you can find a free bit in the cflag on all platforms, creating an asm-generic/termbits.h might be a good idea? Alan should probably comment on that first though. > diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h > index 3c8a6aa..3db78cc 100644 > --- a/include/linux/serial_reg.h > +++ b/include/linux/serial_reg.h > @@ -188,6 +188,7 @@ > #define UART_FCTR_RTS_8DELAY 0x03 > #define UART_FCTR_IRDA 0x04 /* IrDa data encode select */ > #define UART_FCTR_TX_INT 0x08 /* Tx interrupt type select */ > +#define UART_FCTR_RS485 0x08 /* Auto RS485 direction control */ Please include in the comment which device this refers to (as the entries below do.) > #define UART_FCTR_TRGA 0x00 /* Tx/Rx 550 trigger table select */ > #define UART_FCTR_TRGB 0x10 /* Tx/Rx 650 trigger table select */ > #define UART_FCTR_TRGC 0x20 /* Tx/Rx 654 trigger table select */ -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
