Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751711AbdFFXD7 (ORCPT ); Tue, 6 Jun 2017 19:03:59 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:35762 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751611AbdFFXBg (ORCPT ); Tue, 6 Jun 2017 19:01:36 -0400 From: Palmer Dabbelt To: linux-arch@vger.kernel.org To: linux-kernel@vger.kernel.org To: Arnd Bergmann To: olof@lixom.net Cc: albert@sifive.com Cc: patches@groups.riscv.org Cc: Palmer Dabbelt Subject: [PATCH 12/17] tty: New RISC-V SBI Console Driver Date: Tue, 6 Jun 2017 16:00:02 -0700 Message-Id: <20170606230007.19101-13-palmer@dabbelt.com> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170606230007.19101-1-palmer@dabbelt.com> References: <20170523004107.536-1-palmer@dabbelt.com> <20170606230007.19101-1-palmer@dabbelt.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4205 Lines: 155 This patch adds a new driver for the console availiable via the RISC-V SBI. This console is specified to be used for early boot messages, and is designed to be a very simple (albiet somewhat slow) console that is always availiable. All RISC-V systems have an SBI console. The SBI console is made availiable for early printk messages and is also availiable as a regular console. Signed-off-by: Palmer Dabbelt --- drivers/tty/hvc/Kconfig | 11 +++++ drivers/tty/hvc/Makefile | 1 + drivers/tty/hvc/hvc_sbi.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 114 insertions(+) create mode 100644 drivers/tty/hvc/hvc_sbi.c diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig index 574da15fe618..f3774adab240 100644 --- a/drivers/tty/hvc/Kconfig +++ b/drivers/tty/hvc/Kconfig @@ -114,4 +114,15 @@ config HVCS which will also be compiled when this driver is built as a module. +config HVC_SBI + bool "SBI console support" + depends on RISCV + select HVC_DRIVER + default y + help + This enables support for console output via RISC-V SBI calls, which + is normally used only during boot to output printk. + + If you don't know what do to here, say Y. + endif # TTY diff --git a/drivers/tty/hvc/Makefile b/drivers/tty/hvc/Makefile index 6a2702be76d1..2d63bfe4a96b 100644 --- a/drivers/tty/hvc/Makefile +++ b/drivers/tty/hvc/Makefile @@ -11,3 +11,4 @@ obj-$(CONFIG_HVC_IUCV) += hvc_iucv.o obj-$(CONFIG_HVC_UDBG) += hvc_udbg.o obj-$(CONFIG_HVC_BFIN_JTAG) += hvc_bfin_jtag.o obj-$(CONFIG_HVCS) += hvcs.o +obj-$(CONFIG_HVC_SBI) += hvc_sbi.o diff --git a/drivers/tty/hvc/hvc_sbi.c b/drivers/tty/hvc/hvc_sbi.c new file mode 100644 index 000000000000..e70293fb7b35 --- /dev/null +++ b/drivers/tty/hvc/hvc_sbi.c @@ -0,0 +1,102 @@ +/* + * RISC-V SBI interface to hvc_console.c + * based on drivers-tty/hvc/hvc_udbg.c + * + * Copyright (C) 2008 David Gibson, IBM Corporation + * Copyright (C) 2012 Regents of the University of California + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * 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. + */ + +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "hvc_console.h" + +static int hvc_sbi_tty_put(uint32_t vtermno, const char *buf, int count) +{ + int i; + + for (i = 0; i < count; i++) + sbi_console_putchar(buf[i]); + + return i; +} + +static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count) +{ + int i, c; + + for (i = 0; i < count; i++) { + if ((c = sbi_console_getchar()) < 0) + break; + buf[i] = c; + } + + return i; +} + +static const struct hv_ops hvc_sbi_ops = { + .get_chars = hvc_sbi_tty_get, + .put_chars = hvc_sbi_tty_put, +}; + +static int __init hvc_sbi_init(void) +{ + return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16)); +} +device_initcall(hvc_sbi_init); + +static int __init hvc_sbi_console_init(void) +{ + hvc_instantiate(0, 0, &hvc_sbi_ops); + add_preferred_console("hvc", 0, NULL); + + return 0; +} +console_initcall(hvc_sbi_console_init); + +#ifdef CONFIG_EARLY_PRINTK +static void sbi_console_write(struct console *co, const char *buf, + unsigned int n) +{ + int i; + + for (i = 0; i < n; ++i) { + if (buf[i] == '\n') + sbi_console_putchar('\r'); + sbi_console_putchar(buf[i]); + } +} + +static struct console early_console_dev __initdata = { + .name = "early", + .write = sbi_console_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1 +}; + +static int __init setup_early_printk(char *str) +{ + if (early_console == NULL) { + early_console = &early_console_dev; + register_console(early_console); + } + return 0; +} +early_param("earlyprintk", setup_early_printk); +#endif -- 2.13.0