3 files changed, 8 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 189df0bcab99..c6859b94aaa7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -431,8 +431,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         over the 8254 in addition to over the IO-APIC. The
                         kernel tries to set a sensible default.
 
-        hpet=           [X86-32,HPET] option to disable HPET and use PIT.
-                        Format: disable
+        hpet=           [X86-32,HPET] option to control HPET usage
+                        Format: { enable (default) | disable | force }
+                        disable: disable HPET and use PIT instead
+                        force: allow force enabled of undocumented chips (ICH4, VIA)
 
         com20020=       [HW,NET] ARCnet - COM20020 chipset
                         Format:
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index f8367074da0d..22d8f00c80dc 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -69,12 +69,15 @@ static inline void hpet_clear_mapping(void)
  * HPET command line enable / disable
  */
 static int boot_hpet_disable;
+int hpet_force_user;
 
 static int __init hpet_setup(char* str)
 {
         if (str) {
                 if (!strncmp("disable", str, 7))
                         boot_hpet_disable = 1;
+                if (!strncmp("force", str, 5))
+                        hpet_force_user = 1;
         }
         return 1;
 }
diff --git a/include/asm-x86/hpet.h b/include/asm-x86/hpet.h
index d4ab6db050b6..4f51519fc199 100644
--- a/include/asm-x86/hpet.h
+++ b/include/asm-x86/hpet.h
@@ -64,6 +64,7 @@
 /* hpet memory map physical address */
 extern unsigned long hpet_address;
 extern unsigned long force_hpet_address;
+extern int hpet_force_user;
 extern int is_hpet_enabled(void);
 extern int hpet_enable(void);
 extern unsigned long hpet_readl(unsigned long a);