Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754619AbaDRWVc (ORCPT ); Fri, 18 Apr 2014 18:21:32 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:55412 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329AbaDRWUW (ORCPT ); Fri, 18 Apr 2014 18:20:22 -0400 From: Rob Herring To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Cc: Greg Kroah-Hartman , Jiri Slaby , Catalin Marinas , Russell King , Will Deacon , Arnd Bergmann , Rob Herring Subject: [PATCH v2 5/7] tty/serial: add arm/arm64 semihosting earlycon Date: Fri, 18 Apr 2014 17:19:58 -0500 Message-Id: <1397859600-11507-6-git-send-email-robherring2@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1397859600-11507-1-git-send-email-robherring2@gmail.com> References: <1397859600-11507-1-git-send-email-robherring2@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rob Herring Add earlycon support for the arm/arm64 semihosting debug serial interface. This allows enabling a debug console when early_params are processed. This is based on the arm64 earlyprintk smh support and is intended to replace it. Signed-off-by: Rob Herring Cc: Greg Kroah-Hartman Cc: Jiri Slaby --- v2: - Add support for ARM32 semihosting - Rework the kernel-parameters.txt description - Update copyright per Catalin. Documentation/kernel-parameters.txt | 2 + drivers/tty/serial/Kconfig | 10 +++++ drivers/tty/serial/Makefile | 1 + drivers/tty/serial/earlycon-arm-semihost.c | 61 ++++++++++++++++++++++++++++++ 4 files changed, 74 insertions(+) create mode 100644 drivers/tty/serial/earlycon-arm-semihost.c diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 15b5fcca..9e9935a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -906,6 +906,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. must already be setup and configured. Options are not yet supported. + smh Use ARM semihosting calls for early console. + earlyprintk= [X86,SH,BLACKFIN,ARM] earlyprintk=vga earlyprintk=efi diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index b1b23c2..8cce654 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -73,6 +73,16 @@ config SERIAL_AMBA_PL011_CONSOLE your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.) +config SERIAL_EARLYCON_ARM_SEMIHOST + bool "Early console using ARM semihosting" + depends on ARM64 || ARM + select SERIAL_EARLYCON + help + Support for early debug console using ARM semihosting. This enables + the console before standard serial driver is probed. This is enabled + with "earlycon=smh" on the kernel command line. The console is + enabled when early_param is processed. + config SERIAL_SB1250_DUART tristate "BCM1xxx on-chip DUART serial support" depends on SIBYTE_SB1xxx_SOC=y diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index 8af1415..9965b65 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_SERIAL_CORE) += serial_core.o obj-$(CONFIG_SERIAL_21285) += 21285.o obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o +obj-$(CONFIG_SERIAL_EARLYCON_ARM_SEMIHOST) += earlycon-arm-semihost.o # These Sparc drivers have to appear before others such as 8250 # which share ttySx minor node space. Otherwise console device diff --git a/drivers/tty/serial/earlycon-arm-semihost.c b/drivers/tty/serial/earlycon-arm-semihost.c new file mode 100644 index 0000000..383db10 --- /dev/null +++ b/drivers/tty/serial/earlycon-arm-semihost.c @@ -0,0 +1,61 @@ +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Marc Zyngier + * + * Adapted for ARM and earlycon: + * Copyright (C) 2014 Linaro Ltd. + * Author: Rob Herring + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ +#include +#include +#include +#include + +#ifdef CONFIG_THUMB2_KERNEL +#define SEMIHOST_SWI "0xab" +#else +#define SEMIHOST_SWI "0x123456" +#endif + +/* + * Semihosting-based debug console + */ +static void smh_putc(struct uart_port *port, int c) +{ +#ifdef CONFIG_ARM64 + asm volatile("mov x1, %0\n" + "mov x0, #3\n" + "hlt 0xf000\n" + : : "r" (&c) : "x0", "x1", "memory"); +#else + asm volatile("mov r1, %0\n" + "mov r0, #3\n" + "svc " SEMIHOST_SWI "\n" + : : "r" (&c) : "r0", "r1", "memory"); +#endif +} + +static void smh_write(struct console *con, const char *s, unsigned n) +{ + struct earlycon_device *dev = con->data; + uart_console_write(&dev->port, s, n, smh_putc); +} + +int __init early_smh_setup(struct earlycon_device *device, const char *opt) +{ + device->con->write = smh_write; + return 0; +} +EARLYCON_DECLARE(smh, early_smh_setup); -- 1.9.1 -- 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/