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Message-ID: <CAMuHMdVwzQ11QycQTTc2-=-e+fRJCvANpsQ6xO_qwnvUFcKnyQ@mail.gmail.com>
Date: Wed, 7 Jun 2017 09:15:41 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Linux-Arch <linux-arch@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
albert@...ive.com, patches@...ups.riscv.org,
Greg KH <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 12/17] tty: New RISC-V SBI Console Driver
CC (hypervisor) console folks
On Wed, Jun 7, 2017 at 1:00 AM, Palmer Dabbelt <palmer@...belt.com> wrote:
> 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 <palmer@...belt.com>
> ---
> 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 <linux/console.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/moduleparam.h>
> +#include <linux/types.h>
> +#include <linux/irq.h>
> +
> +#include <asm/sbi.h>
> +
> +#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
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