From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754421AbbKGWEy (ORCPT ); Sat, 7 Nov 2015 17:04:54 -0500 Received: from mail-ig0-f176.google.com ([209.85.213.176]:37199 "EHLO mail-ig0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611AbbKGWEt (ORCPT ); Sat, 7 Nov 2015 17:04:49 -0500 Subject: Re: [PATCH v2 1/3] tty: Introduce UART_CAP_HW485 To: "Matwey V. Kornilov" References: <1446890976-1817-1-git-send-email-matwey@sai.msu.ru> <563DED05.9010004@hurleysoftware.com> <563E1997.40306@hurleysoftware.com> Cc: Greg KH , jslaby@suse.com, linux-serial@vger.kernel.org, linux-kernel From: Peter Hurley Message-ID: <563E757B.8000900@hurleysoftware.com> Date: Sat, 7 Nov 2015 17:04:43 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/07/2015 04:10 PM, Matwey V. Kornilov wrote: > 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? Yes, something like that would be fine. 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)