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Subject[patch 21/26] Xen-paravirt_ops: Use the hvc console infrastructure for Xen console
Implement a Xen back-end for hvc console.

From: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>

---
arch/i386/xen/Kconfig | 1
arch/i386/xen/events.c | 3 -
drivers/Makefile | 3 +
drivers/xen/Makefile | 1
drivers/xen/hvc-console.c | 134 +++++++++++++++++++++++++++++++++++++++++++++
include/xen/events.h | 1
6 files changed, 142 insertions(+), 1 deletion(-)

===================================================================
--- a/arch/i386/xen/Kconfig
+++ b/arch/i386/xen/Kconfig
@@ -5,6 +5,7 @@ config XEN
config XEN
bool "Enable support for Xen hypervisor"
depends on PARAVIRT && HZ_100 && !PREEMPT && !NO_HZ
+ select HVC_DRIVER
default y
help
This is the Linux Xen port.
===================================================================
--- a/arch/i386/xen/events.c
+++ b/arch/i386/xen/events.c
@@ -209,7 +209,7 @@ static int find_unbound_irq(void)
return irq;
}

-static int bind_evtchn_to_irq(unsigned int evtchn)
+int bind_evtchn_to_irq(unsigned int evtchn)
{
int irq;

@@ -233,6 +233,7 @@ static int bind_evtchn_to_irq(unsigned i

return irq;
}
+EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);

static int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
{
===================================================================
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -14,6 +14,9 @@ obj-$(CONFIG_ACPI) += acpi/
# was used and do nothing if so
obj-$(CONFIG_PNP) += pnp/
obj-$(CONFIG_ARM_AMBA) += amba/
+
+# Xen is the default console when running as a guest
+obj-$(CONFIG_XEN) += xen/

# char/ comes before serial/ etc so that the VT console is the boot-time
# default.
===================================================================
--- /dev/null
+++ b/drivers/xen/Makefile
@@ -0,0 +1,1 @@
+obj-y += hvc-console.o
===================================================================
--- /dev/null
+++ b/drivers/xen/hvc-console.c
@@ -0,0 +1,134 @@
+/*
+ * xen console driver interface to hvc_console.c
+ *
+ * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
+ *
+ * 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/types.h>
+
+#include <asm/xen/hypervisor.h>
+#include <xen/page.h>
+#include <xen/events.h>
+#include <xen/interface/io/console.h>
+
+#include "../char/hvc_console.h"
+
+#define HVC_COOKIE 0x58656e /* "Xen" in hex */
+
+static struct hvc_struct *hvc;
+static int xencons_irq;
+
+/* ------------------------------------------------------------------ */
+
+static inline struct xencons_interface *xencons_interface(void)
+{
+ return mfn_to_virt(xen_start_info->console.domU.mfn);
+}
+
+static inline void notify_daemon(void)
+{
+ /* Use evtchn: this is called early, before irq is set up. */
+ notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
+}
+
+static int write_console(uint32_t vtermno, const char *data, int len)
+{
+ struct xencons_interface *intf = xencons_interface();
+ XENCONS_RING_IDX cons, prod;
+ int sent = 0;
+
+ cons = intf->out_cons;
+ prod = intf->out_prod;
+ mb();
+ BUG_ON((prod - cons) > sizeof(intf->out));
+
+ while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
+ intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
+
+ wmb();
+ intf->out_prod = prod;
+
+ notify_daemon();
+ return sent;
+}
+
+static int read_console(uint32_t vtermno, char *buf, int len)
+{
+ struct xencons_interface *intf = xencons_interface();
+ XENCONS_RING_IDX cons, prod;
+ int recv = 0;
+
+ cons = intf->in_cons;
+ prod = intf->in_prod;
+ mb();
+ BUG_ON((prod - cons) > sizeof(intf->in));
+
+ while (cons != prod && recv < len)
+ buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++,intf->in)];
+
+ mb();
+ intf->in_cons = cons;
+
+ notify_daemon();
+ return recv;
+}
+
+static struct hv_ops hvc_ops = {
+ .get_chars = read_console,
+ .put_chars = write_console,
+};
+
+static int __init xen_init(void)
+{
+ struct hvc_struct *hp;
+
+ if (!is_running_on_xen())
+ return 0;
+
+ xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
+ if (xencons_irq < 0)
+ xencons_irq = 0 /* NO_IRQ */;
+ hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
+ if (IS_ERR(hp))
+ return PTR_ERR(hp);
+
+ hvc = hp;
+ return 0;
+}
+
+static void __exit xen_fini(void)
+{
+ if (hvc)
+ hvc_remove(hvc);
+}
+
+static int xen_cons_init(void)
+{
+ if (!is_running_on_xen())
+ return 0;
+
+ hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
+ return 0;
+}
+
+module_init(xen_init);
+module_exit(xen_fini);
+console_initcall(xen_cons_init);
===================================================================
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -3,6 +3,7 @@

#include <linux/irq.h>

+int bind_evtchn_to_irq(unsigned int evtchn);
int bind_evtchn_to_irqhandler(unsigned int evtchn,
irqreturn_t (*handler)(int, void *),
unsigned long irqflags, const char *devname,
--

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