Two and a half weeks ago I submitted a patch to implement RS485 auto direction control on either (or both) the RTS and the DTR lines with varying pre and post delay settings that would work for _all_ uarts that support mctrl. This patch had a variation on the ioctl suggested by Alan Cox, that was a variation on an ioctl that was already in existence in the kernel. The ioctl was devised to allow considerable flexibility, and I hoped that it would be considered for future auto direction control. Sorry for sounding grumpy but is any one interested? On Fri, 2008-12-19 at 16:13 +0100, Laurent Pinchart wrote: > Hi Matthias, > > On Friday 19 December 2008 00:48:34 Matthias Fuchs wrote: > > Hi, > > > > please see my patch for enabling the RS485 half-duplex control below. > > Please note that I am using this on a PowerPC platform. So I needed to > > add the ioctl to the PowerPC header. As Wolfgang stated, it is > > already in the x86 header. I am not sure if I have to post the modification > > on the powerpc header to the PowerPC list or if it will be accepted here > > as well. .... But first I will have to see what you think of this patch > > :-) > > > > Matthias > > > > > > Some Exar UARTs support a auto rs485 mode. In this mode > > the UART's RTS# pin is activated during transmitting and > > can be used to enable a rs485 line driver. This has nothing > > to do with attempts to do this by manually by asserting/ > > deasserting handshake lines. > > [snip] > > + serial_outp(up, UART_LCR, 0xbf); > > + fctr = serial_inp(up, UART_FCTR); > > + if (rs485ctrl.flags & SER_RS485_ENABLED) > > + fctr |= 0x08; > > + else > > + fctr &= ~0x08; > > + serial_outp(up, UART_FCTR, fctr); > > + serial_outp(up, UART_LCR, 0); > > You might also want to add a > > #define UART_FCTR_RS485 0x08 > > to include/linux/serial_reg.h instead of using a hardcoded 0x08 constant. > -- 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
