[PATCH] i386: fix hpet for systems that don't support legacy replacement

Currently the i386 HPET code assumes the entire HPET implementation from the spec is present. This breaks on boxes that do not implement the optional legacy timer replacement functionality portion of the spec. This patch, which is very similar to my x86-64 patch for the same issue, fixes the problem allowing i386 systems that cannot use the HPET for the timer interrupt and RTC to still use the HPET as a time source. I've tested this patch on a system systems without HPET, with HPET but without legacy timer replacement, as well as HPET with legacy timer replacement. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] i386: fix hpet for systems that don't support legacy replacement
Currently the i386 HPET code assumes the entire HPET implementation from the spec is present. This breaks on boxes that do not implement the optional legacy timer replacement functionality portion of the spec. This patch, which is very similar to my x86-64 patch for the same issue, fixes the problem allowing i386 systems that cannot use the HPET for the timer interrupt and RTC to still use the HPET as a time source. I've tested this patch on a system systems without HPET, with HPET but without legacy timer replacement, as well as HPET with legacy timer replacement. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
john stultz · Linus Torvalds
1 parent 5b7abc6fdc
Showing 5 changed files with 37 additions and 27 deletions Side-by-side Diff
arch/i386/kernel/time.c
arch/i386/kernel/time_hpet.c
arch/i386/kernel/timers/timer_hpet.c
arch/i386/kernel/timers/timer_tsc.c
include/asm-i386/hpet.h
@@ -441,7 +441,7 @@
 	set_normalized_timespec(&wall_to_monotonic,
 		-xtime.tv_sec, -xtime.tv_nsec);
  
-	if (hpet_enable() >= 0) {
+	if ((hpet_enable() >= 0) && hpet_use_timer) {
 		printk("Using HPET for base-timer\n");
 	}
  
@@ -26,6 +26,7 @@
 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 */
  
  
  
@@ -73,27 +74,30 @@
 	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);
+	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);
+	}
 	/*
-	 * 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;
  
  
  
@@ -128,13 +132,12 @@
 	 * However, we can do with one timer otherwise using the
 	 * the single HPET timer for system time.
 	 */
-	if (
 #ifdef CONFIG_HPET_EMULATE_RTC
-		!(id & HPET_ID_NUMBER) ||
-#endif
-	    !(id & HPET_ID_LEGSUP))
+	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))
 		return -1;
@@ -152,6 +155,8 @@
 	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;
  
@@ -202,7 +207,8 @@
 #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;
 }
@@ -79,7 +79,7 @@
  
 	eax = hpet_readl(HPET_COUNTER);
 	eax -= hpet_last;	/* hpet delta */
-
+	eax = min(hpet_tick, eax);
 	/*
          * Time offset = (hpet delta) * ( usecs per HPET clock )
 	 *             = (hpet delta) * ( usecs per tick / HPET clocks per tick)
@@ -105,9 +105,12 @@
 	last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
 	rdtsc(last_tsc_low, last_tsc_high);
  
-	offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
-	if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) {
-		int lost_ticks = (offset - hpet_last) / hpet_tick;
+	if (hpet_use_timer)
+		offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
+	else
+		offset = hpet_readl(HPET_COUNTER);
+	if (unlikely(((offset - hpet_last) >= (2*hpet_tick)) && (hpet_last != 0))) {
+		int lost_ticks = ((offset - hpet_last) / hpet_tick) - 1;
 		jiffies_64 += lost_ticks;
 	}
 	hpet_last = offset;
@@ -477,7 +477,7 @@
 	if (cpu_has_tsc) {
 		unsigned long tsc_quotient;
 #ifdef CONFIG_HPET_TIMER
-		if (is_hpet_enabled()){
+		if (is_hpet_enabled() && hpet_use_timer) {
 			unsigned long result, remain;
 			printk("Using TSC for gettimeofday\n");
 			tsc_quotient = calibrate_tsc_hpet(NULL);
@@ -92,6 +92,7 @@
  
 extern unsigned long hpet_tick;  	/* hpet clks count per tick */
 extern unsigned long hpet_address;	/* hpet memory map physical address */
+extern int hpet_use_timer;
  
 extern int hpet_rtc_timer_init(void);
 extern int hpet_enable(void);
...	...	@@ -441,7 +441,7 @@
441	441	set_normalized_timespec(&wall_to_monotonic,
442	442	-xtime.tv_sec, -xtime.tv_nsec);
443	443
444		- if (hpet_enable() >= 0) {
	444	+ if ((hpet_enable() >= 0) && hpet_use_timer) {
445	445	printk("Using HPET for base-timer\n");
446	446	}
447	447
...	...	@@ -26,6 +26,7 @@
26	26	static unsigned long hpet_period; /* fsecs / HPET clock */
27	27	unsigned long hpet_tick; /* hpet clks count per tick */
28	28	unsigned long hpet_address; /* hpet memory map physical address */
	29	+int hpet_use_timer;
29	30
30	31	static int use_hpet; /* can be used for runtime check of hpet */
31	32	static int boot_hpet_disable; /* boottime override for HPET timer */
32	33
33	34
34	35
...	...	@@ -73,27 +74,30 @@
73	74	hpet_writel(0, HPET_COUNTER);
74	75	hpet_writel(0, HPET_COUNTER + 4);
75	76
76		- /*
77		- * Set up timer 0, as periodic with first interrupt to happen at
78		- * hpet_tick, and period also hpet_tick.
79		- */
80		- cfg = hpet_readl(HPET_T0_CFG);
81		- cfg \|= HPET_TN_ENABLE \| HPET_TN_PERIODIC \|
82		- HPET_TN_SETVAL \| HPET_TN_32BIT;
83		- hpet_writel(cfg, HPET_T0_CFG);
	77	+ if (hpet_use_timer) {
	78	+ /*
	79	+ * Set up timer 0, as periodic with first interrupt to happen at
	80	+ * hpet_tick, and period also hpet_tick.
	81	+ */
	82	+ cfg = hpet_readl(HPET_T0_CFG);
	83	+ cfg \|= HPET_TN_ENABLE \| HPET_TN_PERIODIC \|
	84	+ HPET_TN_SETVAL \| HPET_TN_32BIT;
	85	+ hpet_writel(cfg, HPET_T0_CFG);
84	86
	87	+ /*
	88	+ * The first write after writing TN_SETVAL to the config register sets
	89	+ * the counter value, the second write sets the threshold.
	90	+ */
	91	+ hpet_writel(tick, HPET_T0_CMP);
	92	+ hpet_writel(tick, HPET_T0_CMP);
	93	+ }
85	94	/*
86		- * The first write after writing TN_SETVAL to the config register sets
87		- * the counter value, the second write sets the threshold.
88		- */
89		- hpet_writel(tick, HPET_T0_CMP);
90		- hpet_writel(tick, HPET_T0_CMP);
91		-
92		- /*
93	95	* Go!
94	96	*/
95	97	cfg = hpet_readl(HPET_CFG);
96		- cfg \|= HPET_CFG_ENABLE \| HPET_CFG_LEGACY;
	98	+ if (hpet_use_timer)
	99	+ cfg \|= HPET_CFG_LEGACY;
	100	+ cfg \|= HPET_CFG_ENABLE;
97	101	hpet_writel(cfg, HPET_CFG);
98	102
99	103	return 0;
100	104
101	105
102	106
...	...	@@ -128,13 +132,12 @@
128	132	* However, we can do with one timer otherwise using the
129	133	* the single HPET timer for system time.
130	134	*/
131		- if (
132	135	#ifdef CONFIG_HPET_EMULATE_RTC
133		- !(id & HPET_ID_NUMBER) \|\|
134		-#endif
135		- !(id & HPET_ID_LEGSUP))
	136	+ if (!(id & HPET_ID_NUMBER))
136	137	return -1;
	138	+#endif
137	139
	140	+
138	141	hpet_period = hpet_readl(HPET_PERIOD);
139	142	if ((hpet_period < HPET_MIN_PERIOD) \|\| (hpet_period > HPET_MAX_PERIOD))
140	143	return -1;
...	...	@@ -152,6 +155,8 @@
152	155	if (hpet_tick_rem > (hpet_period >> 1))
153	156	hpet_tick++; /* rounding the result */
154	157
	158	+ hpet_use_timer = id & HPET_ID_LEGSUP;
	159	+
155	160	if (hpet_timer_stop_set_go(hpet_tick))
156	161	return -1;
157	162
...	...	@@ -202,7 +207,8 @@
202	207	#endif
203	208
204	209	#ifdef CONFIG_X86_LOCAL_APIC
205		- wait_timer_tick = wait_hpet_tick;
	210	+ if (hpet_use_timer)
	211	+ wait_timer_tick = wait_hpet_tick;
206	212	#endif
207	213	return 0;
208	214	}
...	...	@@ -79,7 +79,7 @@
79	79
80	80	eax = hpet_readl(HPET_COUNTER);
81	81	eax -= hpet_last; /* hpet delta */
82		-
	82	+ eax = min(hpet_tick, eax);
83	83	/*
84	84	* Time offset = (hpet delta) * ( usecs per HPET clock )
85	85	* = (hpet delta) * ( usecs per tick / HPET clocks per tick)
...	...	@@ -105,9 +105,12 @@
105	105	last_offset = ((unsigned long long)last_tsc_high<<32)\|last_tsc_low;
106	106	rdtsc(last_tsc_low, last_tsc_high);
107	107
108		- offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
109		- if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) {
110		- int lost_ticks = (offset - hpet_last) / hpet_tick;
	108	+ if (hpet_use_timer)
	109	+ offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
	110	+ else
	111	+ offset = hpet_readl(HPET_COUNTER);
	112	+ if (unlikely(((offset - hpet_last) >= (2*hpet_tick)) && (hpet_last != 0))) {
	113	+ int lost_ticks = ((offset - hpet_last) / hpet_tick) - 1;
111	114	jiffies_64 += lost_ticks;
112	115	}
113	116	hpet_last = offset;
...	...	@@ -477,7 +477,7 @@
477	477	if (cpu_has_tsc) {
478	478	unsigned long tsc_quotient;
479	479	#ifdef CONFIG_HPET_TIMER
480		- if (is_hpet_enabled()){
	480	+ if (is_hpet_enabled() && hpet_use_timer) {
481	481	unsigned long result, remain;
482	482	printk("Using TSC for gettimeofday\n");
483	483	tsc_quotient = calibrate_tsc_hpet(NULL);
...	...	@@ -92,6 +92,7 @@
92	92
93	93	extern unsigned long hpet_tick; /* hpet clks count per tick */
94	94	extern unsigned long hpet_address; /* hpet memory map physical address */
	95	+extern int hpet_use_timer;
95	96
96	97	extern int hpet_rtc_timer_init(void);
97	98	extern int hpet_enable(void);