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[Xen-devel] [patch 19/24] Xen-paravirt_ops: Use the hvc console infrastructure for Xen console



Implement a Xen back-end for hvc console.

From: Gerd Hoffmann <kraxel@xxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>

---
 arch/i386/xen/Kconfig         |    1
 arch/i386/xen/events.c        |    3
 drivers/char/hvc_console.c    |    4 +
 drivers/xen/console/Makefile  |    3
 drivers/xen/console/hvc_xen.c |  135 ++++++++++++++++++++++++++++++++++++++++++
 include/xen/events.h          |    1
 6 files changed, 145 insertions(+), 2 deletions(-)

===================================================================
--- 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.
===================================================================
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -48,6 +48,10 @@
 #define HVC_MINOR      0
 
 #define TIMEOUT                (10)
+
+#ifndef NO_IRQ
+#define NO_IRQ 0
+#endif
 
 /*
  * Wait this long per iteration while trying to push buffered data to the
===================================================================
--- /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@xxxxxxx>
+ *
+ * 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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