powerpc: udbg-based backend for hvc_console

This 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 <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 43b35d0..19e255c 100644 (file)
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -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

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 438f713..52e1552 100644 (file)
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -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

diff --git a/drivers/char/hvc_udbg.c b/drivers/char/hvc_udbg.c
new file mode 100644 (file)
index 0000000..bd63ba8
--- /dev/null
+++ b/drivers/char/hvc_udbg.c
@@ -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);