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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 40E5FC3815B for ; Mon, 20 Apr 2020 17:51:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CE4320B1F for ; Mon, 20 Apr 2020 17:51:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587405110; bh=7gOwHMf33I6TNw+S4FLqcaoxWx3bzdvNBzFd0fQUG90=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GzV/5zKQJaiebysKoVGzGwKGvF1WIqI1+ZDjC4Nx7ZNpuIsz/8JC6HSlYJutU+JvW wZtnpRvVAUc4gcaAcyoV+H8GIqfJssbKykc1+WrLSINzqdA8RNhpkO1Ry/v1qEWNZK 63ebGDyyL0hIT7XneV9DZum5cUECgA4jza/fp80k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726677AbgDTRvq (ORCPT ); Mon, 20 Apr 2020 13:51:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:60650 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725784AbgDTRvq (ORCPT ); Mon, 20 Apr 2020 13:51:46 -0400 Received: from Mani-XPS-13-9360 (unknown [157.46.94.248]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2F78220B1F; Mon, 20 Apr 2020 17:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587405105; bh=7gOwHMf33I6TNw+S4FLqcaoxWx3bzdvNBzFd0fQUG90=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Fj5fEoiYs58Pu1MBZ8wiyZQCnjuuwVb01vstg2M9wgJV+RCKvH5UDUuNFi5tMnk3D KxxH0CFMd1RH6BOWG5wn+zkBcqrnkDGSN4lvDhuNqwIR2vXtWklzj/PToefHP2IrJo zytu2wFg1Rlgnc6dxTBpguf/6b8vaoPAzf7pnWyo= Date: Mon, 20 Apr 2020 23:21:32 +0530 From: Manivannan Sadhasivam To: Fabrice Gasnier Cc: gregkh@linuxfoundation.org, robh+dt@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, linux-serial@vger.kernel.org, devicetree@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, andy.shevchenko@gmail.com, Erwan LE RAY Subject: Re: [PATCH v2 1/2] tty: serial: Add modem control gpio support for STM32 UART Message-ID: <20200420175132.GA22068@Mani-XPS-13-9360> References: <20200416175729.5550-1-mani@kernel.org> <20200416175729.5550-2-mani@kernel.org> <4d6d6568-aee0-be02-df88-14f4e364b598@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4d6d6568-aee0-be02-df88-14f4e364b598@st.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi, On Fri, Apr 17, 2020 at 03:15:07PM +0200, Fabrice Gasnier wrote: > On 4/16/20 7:57 PM, mani@kernel.org wrote: > > From: Manivannan Sadhasivam > > > > STM32 UART controllers have the built in modem control support using > > dedicated gpios which can be enabled using 'st,hw-flow-ctrl' flag in DT. > > But there might be cases where the board design need to use different > > gpios for modem control. > > > > For supporting such cases, this commit adds modem control gpio support > > to STM32 UART controller using mctrl_gpio driver. > > > > Signed-off-by: Manivannan Sadhasivam > > --- > > drivers/tty/serial/Kconfig | 1 + > > drivers/tty/serial/stm32-usart.c | 43 +++++++++++++++++++++++++++++++- > > drivers/tty/serial/stm32-usart.h | 1 + > > 3 files changed, 44 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig > > index 0aea76cd67ff..e7a6f2130684 100644 > > --- a/drivers/tty/serial/Kconfig > > +++ b/drivers/tty/serial/Kconfig > > @@ -1462,6 +1462,7 @@ config SERIAL_STM32 > > tristate "STMicroelectronics STM32 serial port support" > > select SERIAL_CORE > > depends on ARCH_STM32 || COMPILE_TEST > > + select SERIAL_MCTRL_GPIO if GPIOLIB > > help > > This driver is for the on-chip Serial Controller on > > STMicroelectronics STM32 MCUs. > > diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c > > index 5e93e8d40f59..026982259714 100644 > > --- a/drivers/tty/serial/stm32-usart.c > > +++ b/drivers/tty/serial/stm32-usart.c > > @@ -31,6 +31,7 @@ > > #include > > #include > > > > +#include "serial_mctrl_gpio.h" > > #include "stm32-usart.h" > > > > static void stm32_stop_tx(struct uart_port *port); > > @@ -510,12 +511,29 @@ static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl) > > stm32_set_bits(port, ofs->cr3, USART_CR3_RTSE); > > else > > stm32_clr_bits(port, ofs->cr3, USART_CR3_RTSE); > > + > > + mctrl_gpio_set(stm32_port->gpios, mctrl); > > } > > > > static unsigned int stm32_get_mctrl(struct uart_port *port) > > { > > + struct stm32_port *stm32_port = to_stm32_port(port); > > + int ret; > > Hi Mani, > > Please find few minor remarks and a question from my side. > > 'ret' could be an unsigned int > Ok > > + > > /* This routine is used to get signals of: DCD, DSR, RI, and CTS */ > > - return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; > > + ret = TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; > > + > > + return mctrl_gpio_get(stm32_port->gpios, &ret); > > +} > > + > > +static void stm32_enable_ms(struct uart_port *port) > > +{ > > Just a question here: purpose of your patch is to handle the gpio case. > So you may get modem control interrupts from gpios with this patch. > We will only get CTS gpio interrupt which will get handled by mctrl_gpio driver. > In other drivers, I can see the implementation checks gpio usage (like > in atmel_serial). When there's no gpio, the corresponding interrupt at > the serial controller level is enabled, e.g. : > > if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS)) > ier |= ... > Those drivers support both gpio and hardware modem control interrupts, so they are checking to make sure either one of them is enabled at a time. But on STM32 UART, modem interrupts are not enabled (USART_CR3_CTSIE etc...) > Do you need modem control interrupts in your case ? > Nope. Since modem control interrupts in UART block are not enabled currently, I don't bother about it. > In case the Stinger96 board signals gets fixed in a future revision, > would it be needed to enable modem control interrupts in the USART > controller ? > I don't think so. The current driver supports hardware flow control without using interrupts, so we are fine. > > + mctrl_gpio_enable_ms(to_stm32_port(port)->gpios); > > +} > > + > > +static void stm32_disable_ms(struct uart_port *port) > > +{ > > + mctrl_gpio_disable_ms(to_stm32_port(port)->gpios); > > } > > > > /* Transmit stop */ > > @@ -626,6 +644,9 @@ static void stm32_shutdown(struct uart_port *port) > > u32 val, isr; > > int ret; > > > > + /* Disable modem control interrupts */ > > + stm32_disable_ms(port); > > + > > val = USART_CR1_TXEIE | USART_CR1_TE; > > val |= stm32_port->cr1_irq | USART_CR1_RE; > > val |= BIT(cfg->uart_enable_bit); > > @@ -764,6 +785,12 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, > > cr3 |= USART_CR3_CTSE | USART_CR3_RTSE; > > } > > > > + /* Handle modem control interrupts */ > > + if (UART_ENABLE_MS(port, termios->c_cflag)) > > + stm32_enable_ms(port); > > + else > > + stm32_disable_ms(port); > > + > > usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud); > > > > /* > > @@ -898,6 +925,7 @@ static const struct uart_ops stm32_uart_ops = { > > .throttle = stm32_throttle, > > .unthrottle = stm32_unthrottle, > > .stop_rx = stm32_stop_rx, > > + .enable_ms = stm32_enable_ms, > > .break_ctl = stm32_break_ctl, > > .startup = stm32_startup, > > .shutdown = stm32_shutdown, > > @@ -964,6 +992,19 @@ static int stm32_init_port(struct stm32_port *stm32port, > > ret = -EINVAL; > > return -EINVAL; > > > } > > > > + stm32port->gpios = mctrl_gpio_init(&stm32port->port, 0); > > + if (IS_ERR(stm32port->gpios)) > > Please add error path: add a clk_disable_unprepare() here, before the > return. > Ok. Thanks, Mani > > + return PTR_ERR(stm32port->gpios); > > + > > + /* Both CTS/RTS gpios and "st,hw-flow-ctrl" should not be specified */ > > + if (stm32port->hw_flow_control) { > > + if (mctrl_gpio_to_gpiod(stm32port->gpios, UART_GPIO_CTS) || > > + mctrl_gpio_to_gpiod(stm32port->gpios, UART_GPIO_RTS)) { > > + dev_err(&pdev->dev, "Conflicting RTS/CTS config\n"); > > same here > > Best Regards, > Thanks, > Fabrice > > > + return -EINVAL; > > + } > > + } > > + > > return ret; > > } > > > > diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h > > index db8bf0d4982d..d4c916e78d40 100644 > > --- a/drivers/tty/serial/stm32-usart.h > > +++ b/drivers/tty/serial/stm32-usart.h > > @@ -274,6 +274,7 @@ struct stm32_port { > > bool fifoen; > > int wakeirq; > > int rdr_mask; /* receive data register mask */ > > + struct mctrl_gpios *gpios; /* modem control gpios */ > > }; > > > > static struct stm32_port stm32_ports[STM32_MAX_PORTS]; > >