Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754317AbbKGVLK (ORCPT ); Sat, 7 Nov 2015 16:11:10 -0500 Received: from mail-wm0-f50.google.com ([74.125.82.50]:35525 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752950AbbKGVLI (ORCPT ); Sat, 7 Nov 2015 16:11:08 -0500 MIME-Version: 1.0 In-Reply-To: <563E1997.40306@hurleysoftware.com> References: <1446890976-1817-1-git-send-email-matwey@sai.msu.ru> <563DED05.9010004@hurleysoftware.com> <563E1997.40306@hurleysoftware.com> From: "Matwey V. Kornilov" Date: Sun, 8 Nov 2015 00:10:46 +0300 X-Google-Sender-Auth: 8azQxg2q5nZ8LflAsqjoeddx51k Message-ID: Subject: Re: [PATCH v2 1/3] tty: Introduce UART_CAP_HW485 To: Peter Hurley Cc: Greg KH , jslaby@suse.com, linux-serial@vger.kernel.org, linux-kernel 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: 4763 Lines: 115 2015-11-07 18:32 GMT+03:00 Peter Hurley : > On 11/07/2015 07:39 AM, Matwey V. Kornilov wrote: >> 2015-11-07 15:22 GMT+03:00 Peter Hurley : >>> On 11/07/2015 05:09 AM, Matwey V. Kornilov wrote: >>>> Introduce new capability UART_CAP_HW485 to mark 8250 UARTs which have >>>> hardware support of line direction control. >>> >>> Since capabilities are not exported to user-space, how will user-space >>> know if the port only provides emulated 485 (eg., where only HW485 is >>> acceptable)? >> >> I cannot imagine the case when user really has to care about >> implementation details. >> In both cases the user will be provided with the consistent API >> (TIOCGRS485/TIOCSRS485 ioctls) resulting into the same behavior. >> Could you please expand your question? > > Well, the entire serial core is a 'consistent' API but yet we > still report to user-space what the port type is. Same with lspci > and lsusb. Yes, that is correct. I mean if you want the knowledge about HW485 be provided to the user-space via some ioctl, then I cannot understand what application is going to do with it. It has single one option: use provided RS485 if it needs RS485, it cannot purchase and install other hardware in runtime. But I think we could add new read-only flag to struct serial_rs485, say SER_RS485_SOFTWARE then user will know that software emulation is being used. Would it be ok? > > Regards, > Peter Hurley > > >>>> Signed-off-by: Matwey V. Kornilov >>>> --- >>>> Changes since v1: >>>> - Commit message has been wrapped >>>> >>>> drivers/tty/serial/8250/8250.h | 1 + >>>> drivers/tty/serial/8250/8250_fintek.c | 1 + >>>> drivers/tty/serial/8250/8250_lpc18xx.c | 1 + >>>> drivers/tty/serial/8250/8250_pci.c | 1 + >>>> 4 files changed, 4 insertions(+) >>>> >>>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h >>>> index d54dcd8..92a4f47 100644 >>>> --- a/drivers/tty/serial/8250/8250.h >>>> +++ b/drivers/tty/serial/8250/8250.h >>>> @@ -69,6 +69,7 @@ struct serial8250_config { >>>> unsigned int flags; >>>> }; >>>> >>>> +#define UART_CAP_HW485 (1 << 7) /* UART has hardware direction control for RS485 */ >>>> #define UART_CAP_FIFO (1 << 8) /* UART has FIFO */ >>>> #define UART_CAP_EFR (1 << 9) /* UART has EFR */ >>>> #define UART_CAP_SLEEP (1 << 10) /* UART has IER sleep */ >>>> diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c >>>> index 8947439..f2831a8 100644 >>>> --- a/drivers/tty/serial/8250/8250_fintek.c >>>> +++ b/drivers/tty/serial/8250/8250_fintek.c >>>> @@ -208,6 +208,7 @@ fintek_8250_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id) >>>> uart.port.iobase = pnp_port_start(dev, 0); >>>> uart.port.iotype = UPIO_PORT; >>>> uart.port.rs485_config = fintek_8250_rs485_config; >>>> + uart.capabilities = UART_CAP_HW485; >>>> >>>> uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF; >>>> if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE) >>>> diff --git a/drivers/tty/serial/8250/8250_lpc18xx.c b/drivers/tty/serial/8250/8250_lpc18xx.c >>>> index 99cd478..9d30276 100644 >>>> --- a/drivers/tty/serial/8250/8250_lpc18xx.c >>>> +++ b/drivers/tty/serial/8250/8250_lpc18xx.c >>>> @@ -175,6 +175,7 @@ static int lpc18xx_serial_probe(struct platform_device *pdev) >>>> uart.port.private_data = data; >>>> uart.port.rs485_config = lpc18xx_rs485_config; >>>> uart.port.serial_out = lpc18xx_uart_serial_out; >>>> + uart.capabilities = UART_CAP_HW485; >>>> >>>> uart.dma = &data->dma; >>>> uart.dma->rxconf.src_maxburst = 1; >>>> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c >>>> index 4097f3f..c7c0ae9 100644 >>>> --- a/drivers/tty/serial/8250/8250_pci.c >>>> +++ b/drivers/tty/serial/8250/8250_pci.c >>>> @@ -1599,6 +1599,7 @@ static int pci_fintek_setup(struct serial_private *priv, >>>> port->port.iotype = UPIO_PORT; >>>> port->port.iobase = iobase; >>>> port->port.rs485_config = pci_fintek_rs485_config; >>>> + port->capabilities = UART_CAP_HW485; >>>> >>>> data = devm_kzalloc(&pdev->dev, sizeof(u8), GFP_KERNEL); >>>> if (!data) >>>> >>> >> >> >> > -- With best regards, Matwey V. Kornilov. Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia 119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382 -- 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/