[PATCH] generic-time: add macro to simplify/hide mask constants

Add a CLOCKSOURCE_MASK macro to simplify initializing the mask for a struct
clocksource, and use it to replace literal mask constants in the various
clocksource drivers.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/hpet.c

@@ -6,7 +6,7 @@
 #include <asm/hpet.h>
 #include <asm/io.h>
 
-#define HPET_MASK	0xFFFFFFFF
+#define HPET_MASK	CLOCKSOURCE_MASK(32)
 #define HPET_SHIFT	22
 
 /* FSEC = 10^-15 NSEC = 10^-9 */
@@ -23,7 +23,7 @@ static struct clocksource clocksource_hpet = {
 	.name		= "hpet",
 	.rating		= 250,
 	.read		= read_hpet,
-	.mask		= (cycle_t)HPET_MASK,
+	.mask		= HPET_MASK,
 	.mult		= 0, /* set below */
 	.shift		= HPET_SHIFT,
 	.is_continuous	= 1,

arch/i386/kernel/i8253.c

@@ -69,7 +69,7 @@ static struct clocksource clocksource_pit = {
 	.name	= "pit",
 	.rating = 110,
 	.read	= pit_read,
-	.mask	= (cycle_t)-1,
+	.mask	= CLOCKSOURCE_MASK(64),
 	.mult	= 0,
 	.shift	= 20,
 };

arch/i386/kernel/tsc.c

@@ -337,7 +337,7 @@ static struct clocksource clocksource_tsc = {
 	.name			= "tsc",
 	.rating			= 300,
 	.read			= read_tsc,
-	.mask			= (cycle_t)-1,
+	.mask			= CLOCKSOURCE_MASK(64),
 	.mult			= 0, /* to be set */
 	.shift			= 22,
 	.update_callback	= tsc_update_callback,

drivers/clocksource/acpi_pm.c

@@ -32,7 +32,7 @@
  */
 u32 pmtmr_ioport __read_mostly;
 
-#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
+#define ACPI_PM_MASK CLOCKSOURCE_MASK(24) /* limit it to 24 bits */
 
 static inline u32 read_pmtmr(void)
 {

drivers/clocksource/cyclone.c

@@ -14,7 +14,7 @@
 #define CYCLONE_MPCS_OFFSET	0x51A8		/* offset to select register */
 #define CYCLONE_MPMC_OFFSET	0x51D0		/* offset to count register */
 #define CYCLONE_TIMER_FREQ	99780000	/* 100Mhz, but not really */
-#define CYCLONE_TIMER_MASK	0xFFFFFFFF	/* 32 bit mask */
+#define CYCLONE_TIMER_MASK	CLOCKSOURCE_MASK(32) /* 32 bit mask */
 
 int use_cyclone = 0;
 static void __iomem *cyclone_ptr;
@@ -28,7 +28,7 @@ static struct clocksource clocksource_cyclone = {
 	.name		= "cyclone",
 	.rating		= 250,
 	.read		= read_cyclone,
-	.mask		= (cycle_t)CYCLONE_TIMER_MASK,
+	.mask		= CYCLONE_TIMER_MASK,
 	.mult		= 10,
 	.shift		= 0,
 	.is_continuous	= 1,

include/linux/clocksource.h

@@ -65,6 +65,8 @@ struct clocksource {
 	u64 interval_snsecs;
 };
 
+/* simplify initialization of mask field */
+#define CLOCKSOURCE_MASK(bits) (cycle_t)(bits<64 ? ((1ULL<<bits)-1) : -1)
 
 /**
  * clocksource_khz2mult - calculates mult from khz and shift