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  1. 22 8月, 2009 1 次提交
    • J
      x86, hpet: Simplify the HPET code · 5946fa3d
      由 Jan Beulich 提交于 
      On 64-bits, using unsigned long when unsigned int suffices
needlessly creates larger code (due to the need for REX
prefixes), and most of the logic in hpet.c really doesn't need
64-bit operations.

At once this avoids the need for a couple of type casts.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <4A8BC9780200007800010832@vpn.id2.novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      5946fa3d
  3. 12 8月, 2009 1 次提交
  5. 15 6月, 2009 1 次提交
  7. 22 4月, 2009 2 次提交
  9. 23 2月, 2009 3 次提交
  11. 13 2月, 2009 1 次提交
    • J
      x86, hpet: fix for LS21 + HPET = boot hang · b13e2464
      由 john stultz 提交于 
      Between 2.6.23 and 2.6.24-rc1 a change was made that broke IBM LS21
systems that had the HPET enabled in the BIOS, resulting in boot hangs
for x86_64.

Specifically commit b8ce3359, which
merges the i386 and x86_64 HPET code.

Prior to this commit, when we setup the HPET timers in x86_64, we did
the following:

	hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
                    HPET_TN_32BIT, HPET_T0_CFG);

However after the i386/x86_64 HPET merge, we do the following:

	cfg = hpet_readl(HPET_Tn_CFG(timer));
	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
			HPET_TN_SETVAL | HPET_TN_32BIT;
	hpet_writel(cfg, HPET_Tn_CFG(timer));

However on LS21s with HPET enabled in the BIOS, the HPET_T0_CFG register
boots with Level triggered interrupts (HPET_TN_LEVEL) enabled. This
causes the periodic interrupt to be not so periodic, and that results in
the boot time hang I reported earlier in the delay calibration.

My fix: Always disable HPET_TN_LEVEL when setting up periodic mode.
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b13e2464
  13. 06 2月, 2009 1 次提交
  15. 05 2月, 2009 1 次提交
    • P
      x86: fix hpet timer reinit for x86_64 · a6a95406
      由 Pavel Emelyanov 提交于 
      There's a small problem with hpet_rtc_reinit function - it checks
for the:

	hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0

to continue increasing both the HPET_T1_CMP (register) and the
hpet_t1_cmp (variable).

But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp
is 64-bit this condition will always be FALSE once the latter hits
the 32-bit boundary, and we can have a situation, when we don't
increase the HPET_T1_CMP register high enough.

The result - timer stops ticking, since HPET_T1_CMP becomes less,
than the COUNTER and never increased again.

The solution is (based on Linus's suggestion) to not compare 64-bits
(on 64-bit x86), but to do the comparison on 32-bit signed
integers.
Reported-by: NKirill Korotaev <dev@openvz.org>
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      a6a95406
  17. 22 1月, 2009 1 次提交
  19. 12 1月, 2009 1 次提交
  21. 17 12月, 2008 2 次提交
  23. 13 12月, 2008 2 次提交
  25. 25 11月, 2008 1 次提交
  27. 24 11月, 2008 1 次提交
  29. 11 11月, 2008 3 次提交
  31. 16 10月, 2008 8 次提交
  33. 06 9月, 2008 2 次提交
    • T
      x86: HPET: read back compare register before reading counter · 72d43d9b
      由 Thomas Gleixner 提交于 
      After fixing the u32 thinko I sill had occasional hickups on ATI chipsets
with small deltas. There seems to be a delay between writing the compare
register and the transffer to the internal register which triggers the
interrupt. Reading back the value makes sure, that it hit the internal
match register befor we compare against the counter value.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      72d43d9b
    • T
      x86: HPET fix moronic 32/64bit thinko · f7676254
      由 Thomas Gleixner 提交于 
      We use the HPET only in 32bit mode because:
1) some HPETs are 32bit only
2) on i386 there is no way to read/write the HPET atomic 64bit wide

The HPET code unification done by the "moron of the year" did
not take into account that unsigned long is different on 32 and
64 bit.

This thinko results in a possible endless loop in the clockevents
code, when the return comparison fails due to the 64bit/332bit
unawareness. 

unsigned long cnt = (u32) hpet_read() + delta can wrap over 32bit.
but the final compare will fail and return -ETIME causing endless
loops.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      f7676254
  35. 05 9月, 2008 1 次提交
  37. 14 8月, 2008 1 次提交
    • T
      x86: hpet: workaround SB700 BIOS · a6825f1c
      由 Thomas Gleixner 提交于 
      AMD SB700 based systems with spread spectrum enabled use a SMM based
HPET emulation to provide proper frequency setting. The SMM code is
initialized with the first HPET register access and takes some time to
complete. During this time the config register reads 0xffffffff. We
check for max. 1000 loops whether the config register reads a non
0xffffffff value to make sure that HPET is up and running before we go
further. A counting loop is safe, as the HPET access takes thousands
of CPU cycles. On non SB700 based machines this check is only done
once and has no side effects.

Based on a quirk patch from: crane cai <crane.cai@amd.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      a6825f1c
  39. 01 8月, 2008 1 次提交
    • D
      hpet: /dev/hpet - fixes and cleanup · 64a76f66
      由 David Brownell 提交于 
      Minor /dev/hpet updates and bugfixes:

  * Remove dead code, mostly remnants of an incomplete/unusable
    kernel interface ... noted when addressing "sparse" warnings:
      + hpet_unregister() and a routine it calls
      + hpet_task and all references, including hpet_task_lock
      + hpet_data.hd_flags (and HPET_DATA_PLATFORM)

  * Correct and improve boot message:
      + displays *counter* (shared between comparators) bit width,
        not *timer* bit widths (which are often mixed)
      + relabel "timers" as "comparators"; this is less confusing,
        they are not independent like normal timers are (sigh)
      + display MHz not Hz; it's never less than 10 MHz.

  * Tighten and correct the userspace interface code
      + don't accidentally program comparators in 64-bit mode using
        32-bit values ... always force comparators into 32-bit mode
      + provide the correct bit definition flagging comparators with
        periodic capability ... the ABI is unchanged

  * Update Documentation/hpet.txt
      + be more correct and current
      + expand description a bit
      + don't mention that now-gone kernel interface

Plus, add a FIXME comment for something that could cause big trouble
on systems with more capable HPETs than at least Intel seems to ship.

It seems that few folk use this userspace interface; it's not very
usable given the general lack of HPET IRQ routing.  I'm told that
the only real point of it any more is to mmap for fast timestamps;
IMO that's handled better through the gettimeofday() vsyscall.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Acked-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      64a76f66
  41. 25 7月, 2008 1 次提交
  43. 14 7月, 2008 1 次提交
  45. 13 5月, 2008 1 次提交
    • C
      x86: clean up computation of HPET .mult variables · 6fd592da
      由 Carlos R. Mafra 提交于 
      While reading through the HPET code I realized that the
computation of .mult variables could be done with less
lines of code, resulting in a 1.6% text size saving
for hpet.o

So I propose the following patch, which applies against
today's Linus -git tree.

>From 0c6507e400e9ca5f7f14331e18f8c12baf75a9d3 Mon Sep 17 00:00:00 2001
From: Carlos R. Mafra <crmafra@ift.unesp.br>
Date: Mon, 5 May 2008 19:38:53 -0300

The computation of clocksource_hpet.mult

       tmp = (u64)hpet_period << HPET_SHIFT;
       do_div(tmp, FSEC_PER_NSEC);
       clocksource_hpet.mult = (u32)tmp;

can be streamlined if we note that it is equal to

       clocksource_hpet.mult = div_sc(hpet_period, FSEC_PER_NSEC, HPET_SHIFT);

Furthermore, the computation of hpet_clockevent.mult

       uint64_t hpet_freq;

       hpet_freq = 1000000000000000ULL;
       do_div(hpet_freq, hpet_period);
       hpet_clockevent.mult = div_sc((unsigned long) hpet_freq,
                                     NSEC_PER_SEC, hpet_clockevent.shift);

can also be streamlined with the observation that hpet_period and hpet_freq are
inverse to each other (in proper units).

So instead of computing hpet_freq and using (schematically)
div_sc(hpet_freq, 10^9, shift) we use the trick of calling with the
arguments in reverse order, div_sc(10^6, hpet_period, shift).

The different power of ten is due to frequency being in Hertz (1/sec)
and the period being in units of femtosecond. Explicitly,

mult = (hpet_freq * 2^shift)/10^9    (before)
mult = (10^6 * 2^shift)/hpet_period  (after)

because hpet_freq = 10^15/hpet_period.

The comments in the code are also updated to reflect the changes.

As a result,

   text    data     bss     dec     hex filename
   2957     425      92    3474     d92 arch/x86/kernel/hpet.o
   3006     425      92    3523     dc3 arch/x86/kernel/hpet.o.old

a 1.6% reduction in text size.
Signed-off-by: NCarlos R. Mafra <crmafra@ift.unesp.br>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      6fd592da
  47. 01 5月, 2008 1 次提交
  49. 26 4月, 2008 1 次提交