Add acpi_{acquire,release}_glk locking functions.

These functions represent the basic blocks for using the ACPI global
lock that provides mutual exclusion between the OSPM and the BIOS.

No functional change. Okay kettenis@, deraadt@.

2 files changed, 78 insertions, 2 deletions

diff --git a/sys/arch/amd64/amd64/acpi_machdep.c b/sys/arch/amd64/amd64/acpi_machdep.c
index 99fe248dfcc..3b50812f384 100644
--- a/sys/arch/amd64/amd64/acpi_machdep.c
+++ b/sys/arch/amd64/amd64/acpi_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: acpi_machdep.c,v 1.51 2012/10/17 22:49:27 deraadt Exp $	*/
+/*	$OpenBSD: acpi_machdep.c,v 1.52 2012/11/27 17:38:45 pirofti Exp $	*/
 /*
  * Copyright (c) 2005 Thorsten Lockert <tholo@sigmasoft.com>
  *
@@ -168,6 +168,44 @@ havebase:
 	return (1);
 }
 
+/*
+ * Acquire the global lock.  If busy, set the pending bit.  The caller
+ * will wait for notification from the BIOS that the lock is available
+ * and then attempt to acquire it again.
+ */
+int
+acpi_acquire_glk(uint32_t *lock)
+{
+	uint32_t	new, old;
+
+	do {
+		old = *lock;
+		new = (old & ~GL_BIT_PENDING) | GL_BIT_OWNED;
+		if ((old & GL_BIT_OWNED) != 0)
+			new |= GL_BIT_PENDING;
+	} while (x86_atomic_cas_int32(lock, old, new) == 0);
+
+	return ((new & GL_BIT_PENDING) == 0);
+}
+
+/*
+ * Release the global lock, returning whether there is a waiter pending.
+ * If the BIOS set the pending bit, OSPM must notify the BIOS when it
+ * releases the lock.
+ */
+int
+acpi_release_glk(uint32_t *lock)
+{
+	uint32_t	new, old;
+
+	do {
+		old = *lock;
+		new = old & ~(GL_BIT_PENDING | GL_BIT_OWNED);
+	} while (x86_atomic_cas_int32(lock, old, new) == 0);
+
+	return ((old & GL_BIT_PENDING) != 0);
+}
+
 #ifndef SMALL_KERNEL
 
 void
diff --git a/sys/arch/i386/i386/acpi_machdep.c b/sys/arch/i386/i386/acpi_machdep.c
index da46d09db66..0b8fe09efcd 100644
--- a/sys/arch/i386/i386/acpi_machdep.c
+++ b/sys/arch/i386/i386/acpi_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: acpi_machdep.c,v 1.45 2012/10/17 22:49:27 deraadt Exp $	*/
+/*	$OpenBSD: acpi_machdep.c,v 1.46 2012/11/27 17:38:45 pirofti Exp $	*/
 /*
  * Copyright (c) 2005 Thorsten Lockert <tholo@sigmasoft.com>
  *
@@ -183,6 +183,44 @@ havebase:
 	return (1);
 }
 
+/*
+ * Acquire the global lock.  If busy, set the pending bit.  The caller
+ * will wait for notification from the BIOS that the lock is available
+ * and then attempt to acquire it again.
+ */
+int
+acpi_acquire_glk(uint32_t *lock)
+{
+	uint32_t	new, old;
+
+	do {
+		old = *lock;
+		new = (old & ~GL_BIT_PENDING) | GL_BIT_OWNED;
+		if ((old & GL_BIT_OWNED) != 0)
+			new |= GL_BIT_PENDING;
+	} while (i386_atomic_cas_int32(lock, old, new) == 0);
+
+	return ((new & GL_BIT_PENDING) == 0);
+}
+
+/*
+ * Release the global lock, returning whether there is a waiter pending.
+ * If the BIOS set the pending bit, OSPM must notify the BIOS when it
+ * releases the lock.
+ */
+int
+acpi_release_glk(uint32_t *lock)
+{
+	uint32_t	new, old;
+
+	do {
+		old = *lock;
+		new = old & ~(GL_BIT_PENDING | GL_BIT_OWNED);
+	} while (i386_atomic_cas_int32(lock, old, new) == 0);
+
+	return ((old & GL_BIT_PENDING) != 0);
+}
+
 #ifndef SMALL_KERNEL
 
 void