hpet: /dev/hpet - fixes and cleanup

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: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 10 deletions

diff --git a/include/linux/hpet.h b/include/linux/hpet.h
index 6d2626b63a9..79f63a27bce 100644
--- a/include/linux/hpet.h
+++ b/include/linux/hpet.h
@@ -92,23 +92,14 @@ struct hpet {
  * exported interfaces
  */
 
-struct hpet_task {
-	void (*ht_func) (void *);
-	void *ht_data;
-	void *ht_opaque;
-};
-
 struct hpet_data {
 	unsigned long hd_phys_address;
 	void __iomem *hd_address;
 	unsigned short hd_nirqs;
-	unsigned short hd_flags;
 	unsigned int hd_state;	/* timer allocated */
 	unsigned int hd_irq[HPET_MAX_TIMERS];
 };
 
-#define	HPET_DATA_PLATFORM	0x0001	/* platform call to hpet_alloc */
-
 static inline void hpet_reserve_timer(struct hpet_data *hd, int timer)
 {
 	hd->hd_state |= (1 << timer);
@@ -126,7 +117,7 @@ struct hpet_info {
 	unsigned short hi_timer;
 };
 
-#define	HPET_INFO_PERIODIC	0x0001	/* timer is periodic */
+#define HPET_INFO_PERIODIC	0x0010	/* periodic-capable comparator */
 
 #define	HPET_IE_ON	_IO('h', 0x01)	/* interrupt on */
 #define	HPET_IE_OFF	_IO('h', 0x02)	/* interrupt off */