| Message ID | 78efa2b1e2599deff4d838b05b4054ec5ac2976a.1592595601.git.sean.wang@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] tty: serial: don't do termios for BTIF | expand |
On Sat, Jun 20, 2020 at 03:59:14AM +0800, sean.wang@mediatek.com wrote: > From: Sean Wang <sean.wang@mediatek.com> > > 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. > > Fixes: 1c16ae65e250 ("serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC") > Cc: Steven Liu <steven.liu@mediatek.com> > Signed-off-by: Sean Wang <sean.wang@mediatek.com> > Signed-off-by: Ryder Lee <ryder.lee@mediatek.com> > > -- > v1->v2: > no change on termios->c_cflag and refine commit message > > v2->v3: > change the naming from NMOD to NTIO as TIO is a well established prefix > for termios IOCTLs. > > v3->v4: > 1. remove appropriate tag > 2. add the explanation why the termios is required even when the connection > isn't exported to userspace. > --- > drivers/tty/serial/8250/8250.h | 1 + > drivers/tty/serial/8250/8250_port.c | 5 ++++- > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h > index 52bb21205bb6..0d9d3bfe48af 100644 > --- a/drivers/tty/serial/8250/8250.h > +++ b/drivers/tty/serial/8250/8250.h > @@ -82,6 +82,7 @@ struct serial8250_config { > #define UART_CAP_MINI (1 << 17) /* Mini UART on BCM283X family lacks: > * STOP PARITY EPAR SPAR WLEN5 WLEN6 > */ > +#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... thanks, greg k-h
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@mediatek.com wrote: > > From: Sean Wang <sean.wang@mediatek.com> > > > > 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?
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@mediatek.com wrote: > > > From: Sean Wang <sean.wang@mediatek.com> > > > > > > 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
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 52bb21205bb6..0d9d3bfe48af 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -82,6 +82,7 @@ struct serial8250_config { #define UART_CAP_MINI (1 << 17) /* Mini UART on BCM283X family lacks: * STOP PARITY EPAR SPAR WLEN5 WLEN6 */ +#define UART_CAP_NTIO (1 << 18) /* UART doesn't do termios */ #define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */ #define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */ diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 1632f7d25acc..af54db877efe 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -286,7 +286,7 @@ static const struct serial8250_config uart_config[] = { .tx_loadsz = 16, .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT, - .flags = UART_CAP_FIFO, + .flags = UART_CAP_FIFO | UART_CAP_NTIO, }, [PORT_NPCM] = { .name = "Nuvoton 16550", @@ -2640,6 +2640,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, unsigned long flags; unsigned int baud, quot, frac = 0; + if (up->capabilities & UART_CAP_NTIO) + return; + if (up->capabilities & UART_CAP_MINI) { termios->c_cflag &= ~(CSTOPB | PARENB | PARODD | CMSPAR); if ((termios->c_cflag & CSIZE) == CS5 ||