diff options
| -rw-r--r-- | Documentation/timers/hpet.txt | 43 | ||||
| -rw-r--r-- | arch/x86/kernel/hpet.c | 6 | ||||
| -rw-r--r-- | drivers/char/hpet.c | 90 | ||||
| -rw-r--r-- | include/linux/hpet.h | 11 |
4 files changed, 51 insertions, 99 deletions
diff --git a/Documentation/timers/hpet.txt b/Documentation/timers/hpet.txt index 6ad52d9..e7c09ab 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 ad2b15a..82d4591 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 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 @@ 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 6d2626b..79f63a2 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 */ |