[PATCH] i386: fix hpet for systems that don't support legacy replacement (v. A0)

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

[PATCH] i386: fix hpet for systems that don't support legacy replacement (v. A0)

john stultz
Andrew,
        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.

There has been no changes since this patch was sent out to lkml for
review.

Please consider for inclusion into your tree.

thanks
-john

diff -Nru a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
--- a/arch/i386/kernel/time_hpet.c 2005-04-21 13:55:07 -07:00
+++ b/arch/i386/kernel/time_hpet.c 2005-04-21 13:55:07 -07:00
@@ -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);
-
- /*
- * 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);
+ 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;
@@ -128,12 +132,11 @@
  * 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))
@@ -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;
 }
diff -Nru a/arch/i386/kernel/timers/timer_hpet.c b/arch/i386/kernel/timers/timer_hpet.c
--- a/arch/i386/kernel/timers/timer_hpet.c 2005-04-21 13:55:07 -07:00
+++ b/arch/i386/kernel/timers/timer_hpet.c 2005-04-21 13:55:07 -07:00
@@ -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;
diff -Nru a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c
--- a/arch/i386/kernel/timers/timer_tsc.c 2005-04-21 13:55:07 -07:00
+++ b/arch/i386/kernel/timers/timer_tsc.c 2005-04-21 13:55:07 -07:00
@@ -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);
diff -Nru a/include/asm-i386/hpet.h b/include/asm-i386/hpet.h
--- a/include/asm-i386/hpet.h 2005-04-21 13:55:07 -07:00
+++ b/include/asm-i386/hpet.h 2005-04-21 13:55:07 -07:00
@@ -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);


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [hidden email]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] i386: fix hpet for systems that don't support legacy replacement (v. A0)

Jesper Juhl
On Mon, 25 Apr 2005, john stultz wrote:

> Andrew,
> 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.
>
> There has been no changes since this patch was sent out to lkml for
> review.
>

Tiny, tiny nit :

> - if (is_hpet_enabled()){
> + if (is_hpet_enabled() && hpet_use_timer){
                                                       ^^-- space here?


--
Jesper Juhl

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [hidden email]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
Reply | Threaded
Open this post in threaded view
|

[PATCH][Update] i386: fix hpet for systems that don't support legacy replacement (v. A1)

john stultz
Andrew,
        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.

This version fixes whitespace bug and corrects a printk message.

Please consider for inclusion into your tree.

thanks
-john

Changelog
A0: First sent to lkml for review
A1: Fixes whitespace and printk message


diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
--- a/arch/i386/kernel/time.c 2005-04-25 15:42:40 -07:00
+++ b/arch/i386/kernel/time.c 2005-04-25 15:42:40 -07:00
@@ -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");
  }
 
diff -Nru a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
--- a/arch/i386/kernel/time_hpet.c 2005-04-25 15:42:40 -07:00
+++ b/arch/i386/kernel/time_hpet.c 2005-04-25 15:42:40 -07:00
@@ -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);
-
- /*
- * 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);
+ 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;
@@ -128,12 +132,11 @@
  * 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))
@@ -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;
 }
diff -Nru a/arch/i386/kernel/timers/timer_hpet.c b/arch/i386/kernel/timers/timer_hpet.c
--- a/arch/i386/kernel/timers/timer_hpet.c 2005-04-25 15:42:41 -07:00
+++ b/arch/i386/kernel/timers/timer_hpet.c 2005-04-25 15:42:41 -07:00
@@ -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;
diff -Nru a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c
--- a/arch/i386/kernel/timers/timer_tsc.c 2005-04-25 15:42:40 -07:00
+++ b/arch/i386/kernel/timers/timer_tsc.c 2005-04-25 15:42:41 -07:00
@@ -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);
diff -Nru a/include/asm-i386/hpet.h b/include/asm-i386/hpet.h
--- a/include/asm-i386/hpet.h 2005-04-25 15:42:40 -07:00
+++ b/include/asm-i386/hpet.h 2005-04-25 15:42:40 -07:00
@@ -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);


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [hidden email]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/