From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE0F7C48BE8 for ; Wed, 16 Jun 2021 06:30:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A611A613BF for ; Wed, 16 Jun 2021 06:30:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231901AbhFPGcG (ORCPT ); Wed, 16 Jun 2021 02:32:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:44034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231636AbhFPGbX (ORCPT ); Wed, 16 Jun 2021 02:31:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 256A9613C2; Wed, 16 Jun 2021 06:29:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623824957; bh=iS6BFCJPTZwDFmA1LAvtf4xTLCYj46S1LYq86CwMQgQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=z6ey7M1JJAdr2bV7sJVS0ZxM3acoGW6GJ+do5F5Nh+FKTTDgQqkJcll4SF040mvPw wyolF4Du+mA1eoVpdsFA6xi0GOV/emk4a7dyjf1gbu7ljVVR49qjHm/5PY4Cdxi9Dm wgmLeA39Xa2x2g1LhJrOObdSUTPpquF6tUp/V8ak= Date: Wed, 16 Jun 2021 08:29:14 +0200 From: Greg KH To: Jiri Slaby Cc: Lino Sanfilippo , linux@armlinux.org.uk, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: amba-pl011: add RS485 support Message-ID: References: <20210610135004.7585-1-LinoSanfilippo@gmx.de> <5f00ff43-9287-4027-7d80-474da957703c@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5f00ff43-9287-4027-7d80-474da957703c@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 16, 2021 at 08:18:01AM +0200, Jiri Slaby wrote: > On 10. 06. 21, 15:50, Lino Sanfilippo wrote: > > Add basic support for RS485: Provide a callback to configure rs485 > > settings. Handle the RS485 specific part in the functions > > pl011_rs485_tx_start() and pl011_rs485_tx_stop() which extend the generic > > start/stop callbacks. > > Beside via IOCTL from userspace RS485 can be enabled by means of the > > device tree property "rs485-enabled-at-boot-time". > > > > Signed-off-by: Lino Sanfilippo > > --- > > This patch has been tested with a Raspberry Pi CM3. > > > > drivers/tty/serial/amba-pl011.c | 143 +++++++++++++++++++++++++++++++- > > 1 file changed, 140 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > > index 78682c12156a..36e8b938cdba 100644 > > --- a/drivers/tty/serial/amba-pl011.c > > +++ b/drivers/tty/serial/amba-pl011.c > ... > > @@ -1380,6 +1415,31 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c, > > return true; > > } > > +static void pl011_rs485_tx_start(struct uart_amba_port *uap) > > +{ > > + struct uart_port *port = &uap->port; > > + u32 cr; > > + > > + /* Enable transmitter */ > > + cr = pl011_read(uap, REG_CR); > > + cr |= UART011_CR_TXE; > > + /* Disable receiver if half-duplex */ > > + if (!(port->rs485.flags & SER_RS485_RX_DURING_TX)) > > + cr &= ~UART011_CR_RXE; > > + > > + if (port->rs485.flags & SER_RS485_RTS_ON_SEND) > > + cr &= ~UART011_CR_RTS; > > + else > > + cr |= UART011_CR_RTS; > > + > > + pl011_write(cr, uap, REG_CR); > > + > > + if (port->rs485.delay_rts_before_send) > > + mdelay(port->rs485.delay_rts_before_send); > > This is up to 1 second delay with interrupts disabled. Definitely not nice. > 8250 clamps this to 100 ms at least, why did you choose 1000 ms? > > > + > > + uap->rs485_tx_started = true; > > +} > > + > > /* Returns true if tx interrupts have to be (kept) enabled */ > > static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq) > > { > ... > > @@ -1941,6 +2021,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, > > unsigned int lcr_h, old_cr; > > unsigned long flags; > > unsigned int baud, quot, clkdiv; > > + unsigned int bits; > > if (uap->vendor->oversampling) > > clkdiv = 8; > > @@ -1968,25 +2049,32 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, > > switch (termios->c_cflag & CSIZE) { > > case CS5: > > lcr_h = UART01x_LCRH_WLEN_5; > > + bits = 7; > > break; > > case CS6: > > lcr_h = UART01x_LCRH_WLEN_6; > > + bits = 8; > > break; > > case CS7: > > lcr_h = UART01x_LCRH_WLEN_7; > > + bits = 9; > > break; > > default: // CS8 > > lcr_h = UART01x_LCRH_WLEN_8; > > + bits = 10; > > break; > > } > > - if (termios->c_cflag & CSTOPB) > > + if (termios->c_cflag & CSTOPB) { > > lcr_h |= UART01x_LCRH_STP2; > > + bits++; > > + } > > if (termios->c_cflag & PARENB) { > > lcr_h |= UART01x_LCRH_PEN; > > if (!(termios->c_cflag & PARODD)) > > lcr_h |= UART01x_LCRH_EPS; > > if (termios->c_cflag & CMSPAR) > > lcr_h |= UART011_LCRH_SPS; > > + bits++; > > } > > You can do simply: > bits = tty_get_frame_size(termios->c_cflag); > now: > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-testing&id=3ec2ff37230e1c961d4b0d0118dd23c46b5bcdbb I was wondering about that. I'll go drop this patch from my tty-next branch and wait for a new version that fixes the above delay issue and it can use this new call as well. thanks, greg k-h