4 files changed, 51 insertions, 99 deletions

diff --git a/Documentation/timers/hpet.txt b/Documentation/timers/hpet.txt
index 6ad52d9dad6c..e7c09abcfab4 100644
--- a/Documentation/timers/hpet.txt
+++ b/Documentation/timers/hpet.txt
@@ -1,21 +1,32 @@
                 High Precision Event Timer Driver for Linux
 
-The High Precision Event Timer (HPET) hardware is the future replacement
-for the 8254 and Real Time Clock (RTC) periodic timer functionality.
-Each HPET can have up to 32 timers.  It is possible to configure the
-first two timers as legacy replacements for 8254 and RTC periodic timers.
-A specification done by Intel and Microsoft can be found at
-<http://www.intel.com/technology/architecture/hpetspec.htm>.
+The High Precision Event Timer (HPET) hardware follows a specification
+by Intel and Microsoft which can be found at
+
+        http://www.intel.com/technology/architecture/hpetspec.htm
+
+Each HPET has one fixed-rate counter (at 10+ MHz, hence "High Precision")
+and up to 32 comparators.  Normally three or more comparators are provided,
+each of which can generate oneshot interupts and at least one of which has
+additional hardware to support periodic interrupts.  The comparators are
+also called "timers", which can be misleading since usually timers are
+independent of each other ... these share a counter, complicating resets.
+
+HPET devices can support two interrupt routing modes.  In one mode, the
+comparators are additional interrupt sources with no particular system
+role.  Many x86 BIOS writers don't route HPET interrupts at all, which
+prevents use of that mode.  They support the other "legacy replacement"
+mode where the first two comparators block interrupts from 8254 timers
+and from the RTC.
 
 The driver supports detection of HPET driver allocation and initialization
 of the HPET before the driver module_init routine is called.  This enables
 platform code which uses timer 0 or 1 as the main timer to intercept HPET
 initialization.  An example of this initialization can be found in
-arch/i386/kernel/time_hpet.c.
+arch/x86/kernel/hpet.c.
 
-The driver provides two APIs which are very similar to the API found in
-the rtc.c driver.  There is a user space API and a kernel space API.
-An example user space program is provided below.
+The driver provides a userspace API which resembles the API found in the
+RTC driver framework.  An example user space program is provided below.
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -286,15 +297,3 @@ out:
 
         return;
 }
-
-The kernel API has three interfaces exported from the driver:
-
-        hpet_register(struct hpet_task *tp, int periodic)
-        hpet_unregister(struct hpet_task *tp)
-        hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg)
-
-The kernel module using this interface fills in the ht_func and ht_data
-members of the hpet_task structure before calling hpet_register.
-hpet_control simply vectors to the hpet_ioctl routine and has the same
-commands and respective arguments as the user API.  hpet_unregister
-is used to terminate usage of the HPET timer reserved by hpet_register.
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ad2b15a1334d..82d459186fd8 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -115,13 +115,17 @@ static void hpet_reserve_platform_timers(unsigned long id)
         hd.hd_phys_address = hpet_address;
         hd.hd_address = hpet;
         hd.hd_nirqs = nrtimers;
-        hd.hd_flags = HPET_DATA_PLATFORM;
         hpet_reserve_timer(&hd, 0);
 
 #ifdef CONFIG_HPET_EMULATE_RTC
         hpet_reserve_timer(&hd, 1);
 #endif
 
+        /*
+         * NOTE that hd_irq[] reflects IOAPIC input pins (LEGACY_8254
+         * is wrong for i8259!) not the output IRQ.  Many BIOS writers
+         * don't bother configuring *any* comparator interrupts.
+         */
         hd.hd_irq[0] = HPET_LEGACY_8254;
         hd.hd_irq[1] = HPET_LEGACY_RTC;
 
diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index f3981ffe20f0..4bc1da4d4f80 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 @@ static struct clocksource clocksource_hpet = {
         .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 @@ static struct clocksource *hpet_clocksource;
 
 /* 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 @@ struct hpet_dev {
         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 @@ static irqreturn_t hpet_interrupt(int irq, void *data)
                 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 @@ static int hpet_open(struct inode *inode, struct file *file)
 
         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 @@ static int hpet_ioctl_ieon(struct hpet_dev *devp)
         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 @@ static int hpet_ioctl_ieon(struct hpet_dev *devp)
                 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 @@ static int hpet_is_known(struct hpet_data *hdp)
         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 @@ int hpet_alloc(struct hpet_data *hdp)
                 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) {
diff --git a/include/linux/hpet.h b/include/linux/hpet.h
index 6d2626b63a9a..79f63a27bcef 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 */