Re: powerpc: udbg based backend for hvc_console
From: David Gibson <hidden>
Date: 2008-11-06 00:20:17
On Wed, Nov 05, 2008 at 03:53:55PM +1100, Paul Mackerras wrote:
David Gibson writes:quoted
This patch adds a new backend for the hvc console based on the low-level udbg callbacks. This effectively implements a working runtime console in terms of the simple udbg primitives. This is kind of a hack - since udbg isn't something you really want to be using routinely - but it's really useful during bringup. This can be used to quickly implement a userspace usable console while you're working on a proper driver for whatever console I/O device the hardware has. Or, it can be used to avoid writing a full blown tty/console driver entirely for quick-and-dirty I/O hardware that will later be replaced by something else.Since only powerpc has udbg, shouldn't the Kconfig option depend on PPC?
Ah.. yes, yes it should. Forgot that hvconsole was used on non-powerpc as well. Corrected patch below. powerpc: udbg based backend for hvc_console This patch adds a new backend for the hvc console based on the low-level udbg callbacks. This effectively implements a working runtime console in terms of the simple udbg primitives. This is kind of a hack - since udbg isn't something you really want to be using routinely - but it's really useful during bringup. This can be used to quickly implement a userspace usable console while you're working on a proper driver for whatever console I/O device the hardware has. Or, it can be used to avoid writing a full blown tty/console driver entirely for quick-and-dirty I/O hardware that will later be replaced by something else. Signed-off-by: David Gibson <redacted> Index: working-2.6/drivers/char/Kconfig ===================================================================
--- working-2.6.orig/drivers/char/Kconfig 2008-10-31 13:31:49.000000000 +1100
+++ working-2.6/drivers/char/Kconfig 2008-11-06 11:18:22.000000000 +1100@@ -631,6 +631,12 @@ config HVC_XEN help Xen virtual console device driver +config HVC_UDBG + bool "udbg based fake hypervisor console" + depends on PPC && EXPERIMENTAL + select HVC_DRIVER + default n + config VIRTIO_CONSOLE tristate "Virtio console" depends on VIRTIO
Index: working-2.6/drivers/char/Makefile ===================================================================
--- working-2.6.orig/drivers/char/Makefile 2008-10-31 13:31:49.000000000 +1100
+++ working-2.6/drivers/char/Makefile 2008-11-06 11:17:31.000000000 +1100@@ -50,6 +50,7 @@ obj-$(CONFIG_HVC_BEAT) += hvc_beat.o obj-$(CONFIG_HVC_DRIVER) += hvc_console.o obj-$(CONFIG_HVC_IRQ) += hvc_irq.o obj-$(CONFIG_HVC_XEN) += hvc_xen.o +obj-$(CONFIG_HVC_UDBG) += hvc_udbg.o obj-$(CONFIG_VIRTIO_CONSOLE) += virtio_console.o obj-$(CONFIG_RAW_DRIVER) += raw.o obj-$(CONFIG_SGI_SNSC) += snsc.o snsc_event.o
Index: working-2.6/drivers/char/hvc_udbg.c ===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ working-2.6/drivers/char/hvc_udbg.c 2008-11-06 11:17:31.000000000 +1100@@ -0,0 +1,96 @@ +/* + * udbg interface to hvc_console.c + * + * (C) Copyright David Gibson, IBM Corporation 2008. + * + * 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; either version 2 of the License, or + * (at your option) any later version. + * + * 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, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#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/udbg.h> + +#include "hvc_console.h" + +struct hvc_struct *hvc_udbg_dev; + +static int hvc_udbg_put(uint32_t vtermno, const char *buf, int count) +{ + int i; + + for (i = 0; i < count; i++) + udbg_putc(buf[i]); + + return i; +} + +static int hvc_udbg_get(uint32_t vtermno, char *buf, int count) +{ + int i, c; + + if (!udbg_getc_poll) + return 0; + + for (i = 0; i < count; i++) { + if ((c = udbg_getc_poll()) == -1) + break; + buf[i] = c; + } + + return i; +} + +static struct hv_ops hvc_udbg_ops = { + .get_chars = hvc_udbg_get, + .put_chars = hvc_udbg_put, +}; + +static int __init hvc_udbg_init(void) +{ + struct hvc_struct *hp; + + BUG_ON(hvc_udbg_dev); + + hp = hvc_alloc(0, NO_IRQ, &hvc_udbg_ops, 16); + if (IS_ERR(hp)) + return PTR_ERR(hp); + + hvc_udbg_dev = hp; + + return 0; +} +module_init(hvc_udbg_init); + +static void __exit hvc_udbg_exit(void) +{ + if (hvc_udbg_dev) + hvc_remove(hvc_udbg_dev); +} +module_exit(hvc_udbg_exit); + +static int __init hvc_udbg_console_init(void) +{ + hvc_instantiate(0, 0, &hvc_udbg_ops); + add_preferred_console("hvc", 0, NULL); + + return 0; +} +console_initcall(hvc_udbg_console_init);
--
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