X-Git-Url: http://git.onelab.eu/?p=linux-2.6.git;a=blobdiff_plain;f=arch%2Fi386%2Fkernel%2Ftime_hpet.c;h=10a0cbb88e754e81cb01604bca90e989c5b9d50c;hp=86b79c6647a3c0ca8e733fc39bb8e82a9fc5a64b;hb=f7f1b0f1e2fbadeab12d24236000e778aa9b1ead;hpb=e3f6fb6212a7102bdb56ba38fa1e98fe72950475

diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index 86b79c664..10a0cbb88 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -23,9 +23,10 @@
 #include <asm/hpet.h>
 #include <linux/hpet.h>
 
-unsigned long hpet_period;	/* fsecs / HPET clock */
-unsigned long hpet_tick;	/* hpet clks count per tick */
-unsigned long hpet_address;	/* hpet memory map physical address */
+static unsigned long hpet_period;	/* fsecs / HPET clock */
+unsigned long hpet_tick;		/* hpet clks count per tick */
+unsigned long hpet_address;		/* hpet memory map physical address */
+int hpet_use_timer;
 
 static int use_hpet; 		/* can be used for runtime check of hpet */
 static int boot_hpet_disable; 	/* boottime override for HPET timer */
@@ -38,7 +39,7 @@ int hpet_readl(unsigned long a)
 	return readl(hpet_virt_address + a);
 }
 
-void hpet_writel(unsigned long d, unsigned long a)
+static void hpet_writel(unsigned long d, unsigned long a)
 {
 	writel(d, hpet_virt_address + a);
 }
@@ -49,7 +50,7 @@ void hpet_writel(unsigned long d, unsigned long a)
  * comparator value and continue. Next tick can be caught by checking
  * for a change in the comparator value. Used in apic.c.
  */
-void __init wait_hpet_tick(void)
+static void __init wait_hpet_tick(void)
 {
 	unsigned int start_cmp_val, end_cmp_val;
 
@@ -73,26 +74,30 @@ static int hpet_timer_stop_set_go(unsigned long tick)
 	hpet_writel(0, HPET_COUNTER);
 	hpet_writel(0, HPET_COUNTER + 4);
 
-	/*
-	 * Set up timer 0, as periodic with first interrupt to happen at
-	 * hpet_tick, and period also hpet_tick.
-	 */
-	cfg = hpet_readl(HPET_T0_CFG);
-	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
-	       HPET_TN_SETVAL | HPET_TN_32BIT;
-	hpet_writel(cfg, HPET_T0_CFG);
-	/*
-	 * Some systems seems to need two writes to HPET_T0_CMP,
-	 * to get interrupts working
-	 */
-	hpet_writel(tick, HPET_T0_CMP);
-	hpet_writel(tick, HPET_T0_CMP);
+	if (hpet_use_timer) {
+		/*
+		 * Set up timer 0, as periodic with first interrupt to happen at
+		 * hpet_tick, and period also hpet_tick.
+		 */
+		cfg = hpet_readl(HPET_T0_CFG);
+		cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
+		       HPET_TN_SETVAL | HPET_TN_32BIT;
+		hpet_writel(cfg, HPET_T0_CFG);
 
+		/*
+		 * The first write after writing TN_SETVAL to the config register sets
+		 * the counter value, the second write sets the threshold.
+		 */
+		hpet_writel(tick, HPET_T0_CMP);
+		hpet_writel(tick, HPET_T0_CMP);
+	}
 	/*
  	 * Go!
  	 */
 	cfg = hpet_readl(HPET_CFG);
-	cfg |= HPET_CFG_ENABLE | HPET_CFG_LEGACY;
+	if (hpet_use_timer)
+		cfg |= HPET_CFG_LEGACY;
+	cfg |= HPET_CFG_ENABLE;
 	hpet_writel(cfg, HPET_CFG);
 
 	return 0;
@@ -121,13 +126,17 @@ int __init hpet_enable(void)
 	id = hpet_readl(HPET_ID);
 
 	/*
-	 * We are checking for value '1' or more in number field.
-	 * So, we are OK with HPET_EMULATE_RTC part too, where we need
-	 * to have atleast 2 timers.
+	 * We are checking for value '1' or more in number field if
+	 * CONFIG_HPET_EMULATE_RTC is set because we will need an
+	 * additional timer for RTC emulation.
+	 * However, we can do with one timer otherwise using the
+	 * the single HPET timer for system time.
 	 */
-	if (!(id & HPET_ID_NUMBER) ||
-	    !(id & HPET_ID_LEGSUP))
+#ifdef CONFIG_HPET_EMULATE_RTC
+	if (!(id & HPET_ID_NUMBER))
 		return -1;
+#endif
+
 
 	hpet_period = hpet_readl(HPET_PERIOD);
 	if ((hpet_period < HPET_MIN_PERIOD) || (hpet_period > HPET_MAX_PERIOD))
@@ -146,6 +155,8 @@ int __init hpet_enable(void)
 	if (hpet_tick_rem > (hpet_period >> 1))
 		hpet_tick++; /* rounding the result */
 
+	hpet_use_timer = id & HPET_ID_LEGSUP;
+
 	if (hpet_timer_stop_set_go(hpet_tick))
 		return -1;
 
@@ -196,7 +207,8 @@ int __init hpet_enable(void)
 #endif
 
 #ifdef CONFIG_X86_LOCAL_APIC
-	wait_timer_tick = wait_hpet_tick;
+	if (hpet_use_timer)
+		wait_timer_tick = wait_hpet_tick;
 #endif
 	return 0;
 }