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>
diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index f3981ff..4bc1da4 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -53,6 +53,11 @@
#define HPET_RANGE_SIZE 1024 /* from HPET spec */
+
+/* WARNING -- don't get confused. These macros are never used
+ * to write the (single) counter, and rarely to read it.
+ * They're badly named; to fix, someday.
+ */
#if BITS_PER_LONG == 64
#define write_counter(V, MC) writeq(V, MC)
#define read_counter(MC) readq(MC)
@@ -77,7 +82,7 @@
.rating = 250,
.read = read_hpet,
.mask = CLOCKSOURCE_MASK(64),
- .mult = 0, /*to be caluclated*/
+ .mult = 0, /* to be calculated */
.shift = 10,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
@@ -86,8 +91,6 @@
/* A lock for concurrent access by app and isr hpet activity. */
static DEFINE_SPINLOCK(hpet_lock);
-/* A lock for concurrent intermodule access to hpet and isr hpet activity. */
-static DEFINE_SPINLOCK(hpet_task_lock);
#define HPET_DEV_NAME (7)
@@ -99,7 +102,6 @@
unsigned long hd_irqdata;
wait_queue_head_t hd_waitqueue;
struct fasync_struct *hd_async_queue;
- struct hpet_task *hd_task;
unsigned int hd_flags;
unsigned int hd_irq;
unsigned int hd_hdwirq;
@@ -173,11 +175,6 @@
writel(isr, &devp->hd_hpet->hpet_isr);
spin_unlock(&hpet_lock);
- spin_lock(&hpet_task_lock);
- if (devp->hd_task)
- devp->hd_task->ht_func(devp->hd_task->ht_data);
- spin_unlock(&hpet_task_lock);
-
wake_up_interruptible(&devp->hd_waitqueue);
kill_fasync(&devp->hd_async_queue, SIGIO, POLL_IN);
@@ -260,8 +257,7 @@
for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
for (i = 0; i < hpetp->hp_ntimer; i++)
- if (hpetp->hp_dev[i].hd_flags & HPET_OPEN
- || hpetp->hp_dev[i].hd_task)
+ if (hpetp->hp_dev[i].hd_flags & HPET_OPEN)
continue;
else {
devp = &hpetp->hp_dev[i];
@@ -504,7 +500,11 @@
devp->hd_irq = irq;
t = devp->hd_ireqfreq;
v = readq(&timer->hpet_config);
- g = v | Tn_INT_ENB_CNF_MASK;
+
+ /* 64-bit comparators are not yet supported through the ioctls,
+ * so force this into 32-bit mode if it supports both modes
+ */
+ g = v | Tn_32MODE_CNF_MASK | Tn_INT_ENB_CNF_MASK;
if (devp->hd_flags & HPET_PERIODIC) {
write_counter(t, &timer->hpet_compare);
@@ -514,6 +514,12 @@
v |= Tn_VAL_SET_CNF_MASK;
writeq(v, &timer->hpet_config);
local_irq_save(flags);
+
+ /* NOTE: what we modify here is a hidden accumulator
+ * register supported by periodic-capable comparators.
+ * We never want to modify the (single) counter; that
+ * would affect all the comparators.
+ */
m = read_counter(&hpet->hpet_mc);
write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare);
} else {
@@ -667,57 +673,6 @@
return 0;
}
-static inline int hpet_tpcheck(struct hpet_task *tp)
-{
- struct hpet_dev *devp;
- struct hpets *hpetp;
-
- devp = tp->ht_opaque;
-
- if (!devp)
- return -ENXIO;
-
- for (hpetp = hpets; hpetp; hpetp = hpetp->hp_next)
- if (devp >= hpetp->hp_dev
- && devp < (hpetp->hp_dev + hpetp->hp_ntimer)
- && devp->hd_hpet == hpetp->hp_hpet)
- return 0;
-
- return -ENXIO;
-}
-
-#if 0
-int hpet_unregister(struct hpet_task *tp)
-{
- struct hpet_dev *devp;
- struct hpet_timer __iomem *timer;
- int err;
-
- if ((err = hpet_tpcheck(tp)))
- return err;
-
- spin_lock_irq(&hpet_task_lock);
- spin_lock(&hpet_lock);
-
- devp = tp->ht_opaque;
- if (devp->hd_task != tp) {
- spin_unlock(&hpet_lock);
- spin_unlock_irq(&hpet_task_lock);
- return -ENXIO;
- }
-
- timer = devp->hd_timer;
- writeq((readq(&timer->hpet_config) & ~Tn_INT_ENB_CNF_MASK),
- &timer->hpet_config);
- devp->hd_flags &= ~(HPET_IE | HPET_PERIODIC);
- devp->hd_task = NULL;
- spin_unlock(&hpet_lock);
- spin_unlock_irq(&hpet_task_lock);
-
- return 0;
-}
-#endif /* 0 */
-
static ctl_table hpet_table[] = {
{
.ctl_name = CTL_UNNUMBERED,
@@ -872,9 +827,12 @@
printk("%s %d", i > 0 ? "," : "", hdp->hd_irq[i]);
printk("\n");
- printk(KERN_INFO "hpet%u: %u %d-bit timers, %Lu Hz\n",
- hpetp->hp_which, hpetp->hp_ntimer,
- cap & HPET_COUNTER_SIZE_MASK ? 64 : 32, hpetp->hp_tick_freq);
+ printk(KERN_INFO
+ "hpet%u: %u comparators, %d-bit %u.%06u MHz counter\n",
+ hpetp->hp_which, hpetp->hp_ntimer,
+ cap & HPET_COUNTER_SIZE_MASK ? 64 : 32,
+ (unsigned) (hpetp->hp_tick_freq / 1000000),
+ (unsigned) (hpetp->hp_tick_freq % 1000000));
mcfg = readq(&hpet->hpet_config);
if ((mcfg & HPET_ENABLE_CNF_MASK) == 0) {
