| Message ID | cc41ea10be9ab96568f0371784e3b9f8d9f434b9.1587577548.git.sean.wang@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] tty: serial: don't do termios for BTIF | expand |
On Thu, Apr 23, 2020 at 02:02:08AM +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. Why does it matter? If the connection isn't exported to userspace, who would run those termios functions on the port? thanks, greg k-h
On Wed, Apr 22, 2020 at 9:05 PM <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. > > Fixes: 1c16ae65e250 ("serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC") > Cc: Steven Liu <steven.liu@mediatek.com> > Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> I didn't suggest this change. I only commented on the name of the macro. > 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. > --- > 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 33ad9d6de532..234d8db470c0 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 0325f2e53b74..abc974b4113f 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", > @@ -2544,6 +2544,9 @@ 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 || > -- > 2.25.1
On Wed, Apr 22, 2020 at 08:09:00PM +0200, Greg KH wrote: > On Thu, Apr 23, 2020 at 02:02:08AM +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. > > Why does it matter? If the connection isn't exported to userspace, who > would run those termios functions on the port? Dropping from my patch queues due to a lack of response, please address this question when you resend this. greg k-h
From: Sean Wang <sean.wang@mediatek.com> >On Thu, Apr 23, 2020 at 02:02:08AM +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. > >Why does it matter? If the connection isn't exported to userspace, who would run those termios functions on the port? The bluetooth driver would use BTIF device as a serdev. The termios function would be called in kernelspace from ttyport_open and then to tty_set_termios defined in drivers/tty/serdev/serdev-ttyport.c. > >thanks, > >greg k-h
From: Sean Wang <sean.wang@mediatek.com> >> >> 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. >> >> Fixes: 1c16ae65e250 ("serial: 8250: of: Add new port type for MediaTek >> BTIF controller on MT7622/23 SoC") >> Cc: Steven Liu <steven.liu@mediatek.com> > >> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > >I didn't suggest this change. I only commented on the name of the macro. my fault. i will remove the tag from next version. > >> Signed-off-by: Sean Wang <sean.wang@mediatek.com> >> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com> >> >> --
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 33ad9d6de532..234d8db470c0 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 0325f2e53b74..abc974b4113f 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", @@ -2544,6 +2544,9 @@ 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 ||