From nobody Mon May 11 11:30:20 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E33CC433F5 for ; Fri, 8 Apr 2022 12:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235697AbiDHM3i (ORCPT ); Fri, 8 Apr 2022 08:29:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230149AbiDHM33 (ORCPT ); Fri, 8 Apr 2022 08:29:29 -0400 Received: from mx07-00178001.pphosted.com (mx07-00178001.pphosted.com [185.132.182.106]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 510EA33DCAB; Fri, 8 Apr 2022 05:27:25 -0700 (PDT) Received: from pps.filterd (m0288072.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 2389j3P9000551; Fri, 8 Apr 2022 14:27:05 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=selector1; bh=OzzsSeRZXTJPRZje9ui1T8+kROrim9zZTezfZrmqwVA=; b=g9pEZNsoYYlGs5g2LsrK5fLiu589Fxw1KHMSO0CId/eEqsrdIBXj6aKTW+eD8ltMsGgE Lmo260J0JhOSP7+0q6M1B/R9dJ8DCktbMGqZ4jU2MR7bKblxcZXYXDj/HLenA4x6JuV1 GxpxUrt+JnIKxaEH85wK6gRR3zIVInqb0/T9CmSzK552YxFgLzHvfOtY4DTLLw1xbbZ5 UDIaiJV5O85hvXJlE1uKarAfUTL6j0LghhtsifE0PWAyBmwTkxVuycc8aH7RWkhJKjM4 kfPbnN04JyVNJ+xhM1hlbpHavSUKqxYxE4CW7HuDrOs7s5HvpWs8CQinBrJROwov5khc 7Q== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3f9wr7r1p9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 08 Apr 2022 14:27:05 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 8EA7B100038; Fri, 8 Apr 2022 14:27:03 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 8666321A21E; Fri, 8 Apr 2022 14:27:03 +0200 (CEST) Received: from localhost (10.75.127.50) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Fri, 8 Apr 2022 14:27:03 +0200 From: Valentin Caron To: Greg Kroah-Hartman , Jonathan Corbet CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Erwan Le Ray , Valentin Caron , , , , , Subject: [PATCH V2 1/3] serial: stm32: remove infinite loop possibility in putchar function Date: Fri, 8 Apr 2022 14:26:34 +0200 Message-ID: <20220408122636.505737-2-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220408122636.505737-1-valentin.caron@foss.st.com> References: <20220408122636.505737-1-valentin.caron@foss.st.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.75.127.50] X-ClientProxiedBy: SFHDAG2NODE1.st.com (10.75.127.4) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-04-08_04,2022-04-08_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rework stm32_usart_console_putchar() function in order to anticipate the case where the character can never be sent. Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 12 +++++++++--- drivers/tty/serial/stm32-usart.h | 2 ++ 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-us= art.c index 87b5cd4c9743..83895da84891 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1645,10 +1645,16 @@ static void stm32_usart_console_putchar(struct uart= _port *port, unsigned char ch { struct stm32_port *stm32_port =3D to_stm32_port(port); const struct stm32_usart_offsets *ofs =3D &stm32_port->info->ofs; + u32 isr; + int ret; =20 - while (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE)) - cpu_relax(); - + ret =3D readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, isr, + (isr & USART_SR_TXE), 100, + STM32_USART_TIMEOUT_USEC); + if (ret !=3D 0) { + dev_err(port->dev, "Error while sending data in UART TX : %d\n", ret); + return; + } writel_relaxed(ch, port->membase + ofs->tdr); } =20 diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-us= art.h index feab952aec16..d734c4a5fd24 100644 --- a/drivers/tty/serial/stm32-usart.h +++ b/drivers/tty/serial/stm32-usart.h @@ -251,6 +251,8 @@ struct stm32_usart_info stm32h7_info =3D { #define RX_BUF_P (RX_BUF_L / 2) /* dma rx buffer period */ #define TX_BUF_L RX_BUF_L /* dma tx buffer length */ =20 +#define STM32_USART_TIMEOUT_USEC USEC_PER_SEC /* 1s timeout in =C2=B5s */ + struct stm32_port { struct uart_port port; struct clk *clk; --=20 2.25.1 From nobody Mon May 11 11:30:20 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97D22C433F5 for ; Fri, 8 Apr 2022 12:27:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235712AbiDHM3r (ORCPT ); Fri, 8 Apr 2022 08:29:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235670AbiDHM33 (ORCPT ); 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Fri, 08 Apr 2022 14:27:04 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 189A2100039; Fri, 8 Apr 2022 14:27:04 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 105DD21A21E; Fri, 8 Apr 2022 14:27:04 +0200 (CEST) Received: from localhost (10.75.127.49) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Fri, 8 Apr 2022 14:27:03 +0200 From: Valentin Caron To: Greg Kroah-Hartman , Jonathan Corbet CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Erwan Le Ray , Valentin Caron , , , , , Subject: [PATCH V2 2/3] serial: stm32: add KGDB support Date: Fri, 8 Apr 2022 14:26:35 +0200 Message-ID: <20220408122636.505737-3-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220408122636.505737-1-valentin.caron@foss.st.com> References: <20220408122636.505737-1-valentin.caron@foss.st.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.75.127.49] X-ClientProxiedBy: SFHDAG2NODE1.st.com (10.75.127.4) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-04-08_04,2022-04-08_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add support for KGDB in stm32 serial driver by implementing characters polling callbacks (poll_init, poll_get_char and poll_put_char). Signed-off-by: Erwan Le Ray Signed-off-by: Jean Philippe Romain Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 37 ++++++++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-us= art.c index 83895da84891..4307c822afe4 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -37,6 +37,7 @@ =20 static void stm32_usart_stop_tx(struct uart_port *port); static void stm32_usart_transmit_chars(struct uart_port *port); +static void __maybe_unused stm32_usart_console_putchar(struct uart_port *p= ort, unsigned char ch); =20 static inline struct stm32_port *to_stm32_port(struct uart_port *port) { @@ -1222,6 +1223,33 @@ static void stm32_usart_pm(struct uart_port *port, u= nsigned int state, } } =20 +#if defined(CONFIG_CONSOLE_POLL) + + /* Callbacks for characters polling in debug context (i.e. KGDB). */ +static int stm32_usart_poll_init(struct uart_port *port) +{ + struct stm32_port *stm32_port =3D to_stm32_port(port); + + return clk_prepare_enable(stm32_port->clk); +} + +static int stm32_usart_poll_get_char(struct uart_port *port) +{ + struct stm32_port *stm32_port =3D to_stm32_port(port); + const struct stm32_usart_offsets *ofs =3D &stm32_port->info->ofs; + + if (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_RXNE)) + return NO_POLL_CHAR; + + return readl_relaxed(port->membase + ofs->rdr) & stm32_port->rdr_mask; +} + +static void stm32_usart_poll_put_char(struct uart_port *port, unsigned cha= r ch) +{ + stm32_usart_console_putchar(port, ch); +} +#endif /* CONFIG_CONSOLE_POLL */ + static const struct uart_ops stm32_uart_ops =3D { .tx_empty =3D stm32_usart_tx_empty, .set_mctrl =3D stm32_usart_set_mctrl, @@ -1243,6 +1271,11 @@ static const struct uart_ops stm32_uart_ops =3D { .request_port =3D stm32_usart_request_port, .config_port =3D stm32_usart_config_port, .verify_port =3D stm32_usart_verify_port, +#if defined(CONFIG_CONSOLE_POLL) + .poll_init =3D stm32_usart_poll_init, + .poll_get_char =3D stm32_usart_poll_get_char, + .poll_put_char =3D stm32_usart_poll_put_char, +#endif /* CONFIG_CONSOLE_POLL */ }; =20 /* @@ -1640,8 +1673,7 @@ static int stm32_usart_serial_remove(struct platform_= device *pdev) return 0; } =20 -#ifdef CONFIG_SERIAL_STM32_CONSOLE -static void stm32_usart_console_putchar(struct uart_port *port, unsigned c= har ch) +static void __maybe_unused stm32_usart_console_putchar(struct uart_port *p= ort, unsigned char ch) { struct stm32_port *stm32_port =3D to_stm32_port(port); const struct stm32_usart_offsets *ofs =3D &stm32_port->info->ofs; @@ -1658,6 +1690,7 @@ static void stm32_usart_console_putchar(struct uart_p= ort *port, unsigned char ch writel_relaxed(ch, port->membase + ofs->tdr); } =20 +#ifdef CONFIG_SERIAL_STM32_CONSOLE static void stm32_usart_console_write(struct console *co, const char *s, unsigned int cnt) { --=20 2.25.1 From nobody Mon May 11 11:30:20 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B2BEC433FE for ; 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Fri, 8 Apr 2022 14:27:04 +0200 From: Valentin Caron To: Greg Kroah-Hartman , Jonathan Corbet CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Erwan Le Ray , Valentin Caron , , , , , Subject: [PATCH V2 3/3] serial: stm32: add earlycon support Date: Fri, 8 Apr 2022 14:26:36 +0200 Message-ID: <20220408122636.505737-4-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220408122636.505737-1-valentin.caron@foss.st.com> References: <20220408122636.505737-1-valentin.caron@foss.st.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.75.127.51] X-ClientProxiedBy: SFHDAG2NODE1.st.com (10.75.127.4) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-04-08_04,2022-04-08_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add early console support in stm32 uart driver. Signed-off-by: Alexandre Torgue Signed-off-by: Valentin Caron --- .../admin-guide/kernel-parameters.txt | 6 +++ drivers/tty/serial/Kconfig | 1 + drivers/tty/serial/stm32-usart.c | 51 +++++++++++++++++++ 3 files changed, 58 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 3f1cc5e317ed..e941c3351c7a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1264,6 +1264,12 @@ address must be provided, and the serial port must already be setup and configured. =20 + stm32, + Use early console provided by ST Microelectronics + serial driver for STM32 SoCs. A valid base address + must be provided, and the serial port must already + be setup and configured. + earlyprintk=3D [X86,SH,ARM,M68k,S390] earlyprintk=3Dvga earlyprintk=3Dsclp diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 6949e883ffab..ed59de8d2e11 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -1443,6 +1443,7 @@ config SERIAL_STM32_CONSOLE bool "Support for console on STM32" depends on SERIAL_STM32=3Dy select SERIAL_CORE_CONSOLE + select SERIAL_EARLYCON =20 config SERIAL_MVEBU_UART bool "Marvell EBU serial port support" diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-us= art.c index 4307c822afe4..65988e6efaa2 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1766,6 +1766,57 @@ static struct console stm32_console =3D { #define STM32_SERIAL_CONSOLE NULL #endif /* CONFIG_SERIAL_STM32_CONSOLE */ =20 +#ifdef CONFIG_SERIAL_EARLYCON +static void early_stm32_usart_console_putchar(struct uart_port *port, unsi= gned char ch) +{ + struct stm32_usart_info *info =3D port->private_data; + + while (!(readl_relaxed(port->membase + info->ofs.isr) & USART_SR_TXE)) + cpu_relax(); + + writel_relaxed(ch, port->membase + info->ofs.tdr); +} + +static void early_stm32_serial_write(struct console *console, const char *= s, unsigned int count) +{ + struct earlycon_device *device =3D console->data; + struct uart_port *port =3D &device->port; + + uart_console_write(port, s, count, early_stm32_usart_console_putchar); +} + +static int __init early_stm32_h7_serial_setup(struct earlycon_device *devi= ce, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data =3D &stm32h7_info; + device->con->write =3D early_stm32_serial_write; + return 0; +} + +static int __init early_stm32_f7_serial_setup(struct earlycon_device *devi= ce, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data =3D &stm32f7_info; + device->con->write =3D early_stm32_serial_write; + return 0; +} + +static int __init early_stm32_f4_serial_setup(struct earlycon_device *devi= ce, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data =3D &stm32f4_info; + device->con->write =3D early_stm32_serial_write; + return 0; +} + +OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup); +#endif /* CONFIG_SERIAL_EARLYCON */ + static struct uart_driver stm32_usart_driver =3D { .driver_name =3D DRIVER_NAME, .dev_name =3D STM32_SERIAL_NAME, --=20 2.25.1