On Mon, Jun 29, 2020 at 11:29:27AM +0300, Andy Shevchenko wrote: > On Sat, Jun 27, 2020 at 04:12:22PM +0200, Greg KH wrote: > > On Sat, Jun 20, 2020 at 03:59:14AM +0800, sean.wang@xxxxxxxxxxxx wrote: > > > From: Sean Wang <sean.wang@xxxxxxxxxxxx> > > > > > > Bluetooth Interface (BTIF) is designed dedicatedly for MediaTek SOC with > > > BT in order to be instead of the UART interface between BT module and Host > > > CPU, and not exported to user space to access. > > > > > > As the UART design, BTIF will be an APB slave and can transmit or receive > > > data by MCU access, but doesn't provide termios function like baudrate and > > > flow control setup. > > > > > > Even LCR on offset 0xC that is just a FAKELCR > > > a. If FAKELCR[7] is equaled to 1, RBR(0x00), THR(0x00), IER(0x04) > > > will not be readable/writable. > > > > > > b. If FAKELCR is equaled to 0xBF, RBR(0x00), THR(0x00), IER(0x04), > > > IIR(0x08), and LSR(0x14) will not be readable/writable. > > > > > > So adding a new capability 'UART_CAP_NTIO' for the unusual unsupported > > > case. > > > > > > The bluetooth driver would use BTIF device as a serdev. So the termios > > > still function would be called in kernelspace from ttyport_open in > > > drivers/tty/serdev/serdev-ttyprt.c. > > > > +#define UART_CAP_NTIO (1 << 18) /* UART doesn't do termios */ > > > > Naming is hard. I will never remember what "NTIO" is, how about we make > > it explicit: > > define UART_CAP_IGNORE_TERMIOS > > > > And the _CAP_ name is getting out of hand, this isn't a "capability", > > it's a "quirk for this port" but that's a battle to worry about later... > > For quirks we have a separate field in struct uart_port. Perhaps that can be used? That would be much nicer, if possible. thanks, greg k-h
