From ba13dc980ddf4db54b7ed9ff0af75ee38340fd9f Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 21 Mar 2007 12:03:27 -0400
Subject: [PATCH] lguest: TSC clocksource

Add rudimentary TSC-based clocksource support.  Needs to be enhanced
for frequency scaling.

Signed-off-by: James Morris <jmorris@namei.org>
---
 arch/i386/kernel/tsc.c        |    1 +
 arch/i386/lguest/hypercalls.c |    3 +++
 arch/i386/lguest/lguest.c     |   25 +++++++++++++++++++++++++
 include/asm-i386/lguest.h     |    2 ++
 4 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index b5dc068..c1d05a8 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -24,6 +24,7 @@ #include "mach_timer.h"
  * an extra value to store the TSC freq
  */
 unsigned int tsc_khz;
+EXPORT_SYMBOL_GPL(tsc_khz);
 
 int tsc_disable;
 
diff --git a/arch/i386/lguest/hypercalls.c b/arch/i386/lguest/hypercalls.c
index 30b933f..faf5be0 100644
--- a/arch/i386/lguest/hypercalls.c
+++ b/arch/i386/lguest/hypercalls.c
@@ -18,6 +18,7 @@
 #include <linux/uaccess.h>
 #include <linux/syscalls.h>
 #include <linux/mm.h>
+#include <linux/clocksource.h>
 #include <asm/lguest.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -178,6 +179,8 @@ int hypercall(struct lguest *lg, struct 
 		/* We reserve the top pgd entry. */
 		put_user(4U*1024*1024, &lg->lguest_data->reserve_mem);
 		put_user(lg->guestid, &lg->lguest_data->guestid);
+		put_user(clocksource_khz2mult(tsc_khz, 22),
+			 &lg->lguest_data->clock_mult);
 		return 0;
 	}
 	pending = do_hcall(lg, regs);
diff --git a/arch/i386/lguest/lguest.c b/arch/i386/lguest/lguest.c
index 9a273ad..a0b67e3 100644
--- a/arch/i386/lguest/lguest.c
+++ b/arch/i386/lguest/lguest.c
@@ -25,6 +25,7 @@ #include <linux/console.h>
 #include <linux/screen_info.h>
 #include <linux/irq.h>
 #include <linux/interrupt.h>
+#include <linux/clocksource.h>
 #include <asm/paravirt.h>
 #include <asm/lguest.h>
 #include <asm/lguest_user.h>
@@ -358,8 +359,32 @@ static struct irq_chip lguest_irq_contro
 	.unmask		= enable_lguest_irq,
 };
 
+static cycle_t lguest_clock_read(void)
+{
+	/* FIXME: This is just the native one.  Account stolen time! */
+	return paravirt_ops.read_tsc();
+}
+
+/* FIXME: Update iff tsc rate changes. */
+static struct clocksource lguest_clock = {
+	.name		= "lguest",
+	.rating		= 400,
+	.read		= lguest_clock_read,
+	.mask		= CLOCKSOURCE_MASK(64),
+	.mult		= 0, /* to be set */
+	.shift		= 22,
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void lguest_setup_clocksource(void)
+{
+	lguest_clock.mult = lguest_data.clock_mult;
+	clocksource_register(&lguest_clock);
+}
+
 static void lguest_time_init(void)
 {
+	lguest_setup_clocksource();
 	set_irq_handler(0, lguest_time_irq);
 	hcall(LHCALL_TIMER_START,HZ,0,0);
 }
diff --git a/include/asm-i386/lguest.h b/include/asm-i386/lguest.h
index e97650d..7e6a289 100644
--- a/include/asm-i386/lguest.h
+++ b/include/asm-i386/lguest.h
@@ -100,6 +100,8 @@ struct lguest_data
 	unsigned long reserve_mem;
 	/* ID of this guest (used by network driver to set ethernet address) */
 	u16 guestid;
+	/* Multiplier for TSC clock. */
+	u32 clock_mult;
 
 /* Fields initialized by the guest at boot: */
 	/* Instruction range to suppress interrupts even if enabled */
-- 
1.4.2.1