Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754694AbbKLOsi (ORCPT ); Thu, 12 Nov 2015 09:48:38 -0500 Received: from mail-yk0-f172.google.com ([209.85.160.172]:34117 "EHLO mail-yk0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043AbbKLOsh (ORCPT ); Thu, 12 Nov 2015 09:48:37 -0500 MIME-Version: 1.0 In-Reply-To: <1447338836-8785-6-git-send-email-matwey@sai.msu.ru> References: <1447338836-8785-1-git-send-email-matwey@sai.msu.ru> <1447338836-8785-6-git-send-email-matwey@sai.msu.ru> Date: Thu, 12 Nov 2015 16:48:36 +0200 Message-ID: Subject: Re: [PATCH v3 5/5] tty: Add software emulated RS485 support for 8250 From: Andy Shevchenko To: "Matwey V. Kornilov" Cc: Greg Kroah-Hartman , jslaby@suse.com, Peter Hurley , "linux-kernel@vger.kernel.org" , "linux-serial@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9992 Lines: 293 On Thu, Nov 12, 2015 at 4:33 PM, Matwey V. Kornilov wrote: > Implementation of software emulation of RS485 direction handling is based > on omap-serial driver. > Before and after transmission RTS is set to the appropriate value. > One comment below. > Signed-off-by: Matwey V. Kornilov > --- > drivers/tty/serial/8250/8250_port.c | 152 ++++++++++++++++++++++++++++++++++-- > include/linux/serial_8250.h | 2 + > 2 files changed, 148 insertions(+), 6 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c > index 3f6d8a2..b863a12 100644 > --- a/drivers/tty/serial/8250/8250_port.c > +++ b/drivers/tty/serial/8250/8250_port.c > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1299,7 +1300,75 @@ static void serial8250_stop_rx(struct uart_port *port) > serial8250_rpm_put(up); > } > > -static inline void __stop_tx(struct uart_8250_port *p) > +static inline void serial8250_rs485_set_rts_on_send(struct uart_8250_port *p) > +{ > + if (p->port.rs485.flags & SER_RS485_RTS_ON_SEND) > + p->mcr |= UART_MCR_RTS; > + else > + p->mcr &= ~UART_MCR_RTS; > + serial_out(p, UART_MCR, p->mcr); > +} > + > +static inline void serial8250_rs485_set_rts_after_send(struct uart_8250_port *p) > +{ > + if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) > + p->mcr |= UART_MCR_RTS; > + else > + p->mcr &= ~UART_MCR_RTS; > + serial_out(p, UART_MCR, p->mcr); > +} > + > +static __u32 serial8250_rs485_start_tx(struct uart_8250_port *p) > +{ > + if (p->capabilities & UART_CAP_HW485 || !(p->port.rs485.flags & SER_RS485_ENABLED)) > + return 0; > + > + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) > + serial8250_stop_rx(&p->port); > + > + del_timer_sync(&p->rs485_stop_tx_timer); > + > + if (!!(p->port.rs485.flags & SER_RS485_RTS_ON_SEND) != !!(p->mcr & UART_MCR_RTS)) { > + serial8250_rs485_set_rts_on_send(p); > + return p->port.rs485.delay_rts_before_send; > + } > + > + return 0; > +} > + > +static inline void __do_stop_tx_rs485(struct uart_8250_port *p) > +{ > + serial8250_rs485_set_rts_after_send(p); > + /* > + * Empty the RX FIFO, we are not interested in anything > + * received during the half-duplex transmission. > + */ > + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) > + serial8250_clear_fifos(p); > +} > + > +static void serial8250_handle_rs485_stop_tx_timer(unsigned long arg) > +{ > + struct uart_8250_port *p = (struct uart_8250_port*)arg; > + __do_stop_tx_rs485(p); > +} > + > +static inline void __stop_tx_rs485(struct uart_8250_port *p) > +{ > + if (p->capabilities & UART_CAP_HW485 || !(p->port.rs485.flags & SER_RS485_ENABLED)) > + return; It seems you are using this pattern three times. What about static inline bool is_rs485_sw_enabled(struct uart_8250_port *p) { return !(p->capabilities & UART_CAP_HW485) && (p->port.rs485.flags & SER_RS485_ENABLED); } > + > + del_timer_sync(&p->rs485_start_tx_timer); > + > + /* __do_stop_tx_rs485 is going to set RTS according to config AND flush RX FIFO if required */ > + if (p->port.rs485.delay_rts_after_send > 0) { > + mod_timer(&p->rs485_stop_tx_timer, jiffies + p->port.rs485.delay_rts_after_send * HZ / 1000); > + } else { > + __do_stop_tx_rs485(p); > + } > +} > + > +static inline void __do_stop_tx(struct uart_8250_port *p) > { > if (p->ier & UART_IER_THRI) { > p->ier &= ~UART_IER_THRI; > @@ -1308,6 +1377,12 @@ static inline void __stop_tx(struct uart_8250_port *p) > } > } > > +static inline void __stop_tx(struct uart_8250_port *p) > +{ > + __do_stop_tx(p); > + __stop_tx_rs485(p); > +} > + > static void serial8250_stop_tx(struct uart_port *port) > { > struct uart_8250_port *up = up_to_u8250p(port); > @@ -1325,12 +1400,10 @@ static void serial8250_stop_tx(struct uart_port *port) > serial8250_rpm_put(up); > } > > -static void serial8250_start_tx(struct uart_port *port) > +static inline void __start_tx(struct uart_port* port) > { > struct uart_8250_port *up = up_to_u8250p(port); > > - serial8250_rpm_get_tx(up); > - > if (up->dma && !up->dma->tx_dma(up)) > return; > > @@ -1356,6 +1429,29 @@ static void serial8250_start_tx(struct uart_port *port) > } > } > > +static void serial8250_handle_rs485_start_tx_timer(unsigned long arg) > +{ > + struct uart_port* port = (struct uart_port*)arg; > + __start_tx(port); > +} > + > +static void serial8250_start_tx(struct uart_port *port) > +{ > + struct uart_8250_port *up = up_to_u8250p(port); > + __u32 delay; > + > + serial8250_rpm_get_tx(up); > + > + if (timer_pending(&up->rs485_start_tx_timer)) > + return; > + > + if ((delay = serial8250_rs485_start_tx(up))) { > + mod_timer(&up->rs485_start_tx_timer, jiffies + delay * HZ / 1000); > + } else { > + __start_tx(port); > + } > +} > + > static void serial8250_throttle(struct uart_port *port) > { > port->throttle(port); > @@ -1806,6 +1902,16 @@ static void serial8250_put_poll_char(struct uart_port *port, > > #endif /* CONFIG_CONSOLE_POLL */ > > +static inline void serial8250_startup_rs485(struct uart_port *port) > +{ > + struct uart_8250_port *up = up_to_u8250p(port); > + > + if (up->capabilities & UART_CAP_HW485 || !(up->port.rs485.flags & SER_RS485_ENABLED)) > + return; > + > + serial8250_rs485_set_rts_after_send(up); > +} > + > int serial8250_do_startup(struct uart_port *port) > { > struct uart_8250_port *up = up_to_u8250p(port); > @@ -2044,6 +2150,8 @@ dont_test_tx_en: > inb_p(icp); > } > retval = 0; > + > + serial8250_startup_rs485(port); > out: > serial8250_rpm_put(up); > return retval; > @@ -2057,12 +2165,24 @@ static int serial8250_startup(struct uart_port *port) > return serial8250_do_startup(port); > } > > +static inline void serial8250_shutdown_rs485(struct uart_port *port) > +{ > + struct uart_8250_port *up = up_to_u8250p(port); > + > + if (up->capabilities & UART_CAP_HW485 || !(up->port.rs485.flags & SER_RS485_ENABLED)) > + return; > + > + del_timer_sync(&up->rs485_start_tx_timer); > + del_timer_sync(&up->rs485_stop_tx_timer); > +} > + > void serial8250_do_shutdown(struct uart_port *port) > { > struct uart_8250_port *up = up_to_u8250p(port); > unsigned long flags; > > serial8250_rpm_get(up); > + serial8250_shutdown_rs485(port); > /* > * Disable interrupts from this port > */ > @@ -2735,11 +2855,23 @@ serial8250_type(struct uart_port *port) > return uart_config[type].name; > } > > -static int serial8250_rs485_config(struct uart_port *port, > - struct serial_rs485 *rs485) > +static int serial8250_rs485_config(struct uart_port *port, struct serial_rs485 *rs485) > { > + bool need_startup = false; > + > + if (!(port->rs485.flags & SER_RS485_ENABLED) && (rs485->flags & SER_RS485_ENABLED)) { > + need_startup = true; > + } > + if ((port->rs485.flags & SER_RS485_ENABLED) && !(rs485->flags & SER_RS485_ENABLED)) { > + serial8250_shutdown_rs485(port); > + } > + > port->rs485 = *rs485; > port->rs485.flags |= SER_RS485_SOFTWARE; > + > + if (need_startup) > + serial8250_startup_rs485(port); > + > return 0; > } > > @@ -2807,6 +2939,14 @@ void serial8250_set_defaults(struct uart_8250_port *up) > } > > up->port.rs485_config = serial8250_rs485_config; > + init_timer(&up->rs485_stop_tx_timer); > + up->rs485_stop_tx_timer.function = serial8250_handle_rs485_stop_tx_timer; > + up->rs485_stop_tx_timer.data = (unsigned long)up; > + up->rs485_stop_tx_timer.flags |= TIMER_IRQSAFE; > + init_timer(&up->rs485_start_tx_timer); > + up->rs485_start_tx_timer.function = serial8250_handle_rs485_start_tx_timer; > + up->rs485_start_tx_timer.data = (unsigned long)up; > + up->rs485_start_tx_timer.flags |= TIMER_IRQSAFE; > } > EXPORT_SYMBOL_GPL(serial8250_set_defaults); > > diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h > index faa0e03..c4905e7 100644 > --- a/include/linux/serial_8250.h > +++ b/include/linux/serial_8250.h > @@ -86,6 +86,8 @@ struct uart_8250_ops { > struct uart_8250_port { > struct uart_port port; > struct timer_list timer; /* "no irq" timer */ > + struct timer_list rs485_start_tx_timer; /* "rs485 start tx" timer */ > + struct timer_list rs485_stop_tx_timer; /* "rs485 stop tx" timer */ > struct list_head list; /* ports on this IRQ */ > unsigned short capabilities; /* port capabilities */ > unsigned short bugs; /* port bugs */ > -- > 2.6.2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/