From acea2953e72aac894b7fd7e0856fc940cb745c1e 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 755209d..8abc14c 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -26,6 +26,7 @@ static int tsc_enabled;
  * 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 03ec5f6..ee3a3f4 100644
--- a/arch/i386/lguest/hypercalls.c
+++ b/arch/i386/lguest/hypercalls.c
@@ -23,6 +23,7 @@
 #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>
@@ -174,6 +175,8 @@ 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 00c3a95..88254d1 100644
--- a/arch/i386/lguest/lguest.c
+++ b/arch/i386/lguest/lguest.c
@@ -50,6 +50,7 @@ #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>
@@ -597,6 +598,29 @@ static void lguest_time_irq(unsigned int
 	update_process_times(user_mode_vm(get_irq_regs()));
 }
 
+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);
+}
+
 /* At some point in the boot process, we get asked to set up our timing
  * infrastructure.  The kernel doesn't expect timer interrupts before this, but
  * we cleverly initialized the "interrupts" field of lguest_data so that timer
@@ -611,6 +635,7 @@ static void lguest_time_irq(unsigned int
 static void lguest_time_init(void)
 {
 	set_irq_handler(0, lguest_time_irq);
+	lguest_setup_clocksource();
 	hcall(LHCALL_TIMER_READ, 0, 0, 0);
 	enable_lguest_irq(0);
 }
diff --git a/include/asm-i386/lguest.h b/include/asm-i386/lguest.h
index ae11a4b..2373ade 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