/* * Intel & MS High Precision Event Timer Implementation. * * Copyright (C) 2003 Intel Corporation * Venki Pallipadi * (c) Copyright 2004 Hewlett-Packard Development Company, L.P. * Bob Picco * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * The High Precision Event Timer driver. * This driver is closely modelled after the rtc.c driver. * http://www.intel.com/hardwaredesign/hpetspec.htm */ #define HPET_USER_FREQ (64) #define HPET_DRIFT (500) static u32 hpet_nhpet, hpet_max_freq = HPET_USER_FREQ; /* 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) struct hpet_dev { struct hpets *hd_hpets; struct hpet __iomem *hd_hpet; struct hpet_timer __iomem *hd_timer; unsigned long hd_ireqfreq; 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; char hd_name[HPET_DEV_NAME]; }; struct hpets { struct hpets *hp_next; struct hpet __iomem *hp_hpet; unsigned long hp_hpet_phys; struct time_interpolator *hp_interpolator; unsigned long long hp_tick_freq; unsigned long hp_delta; unsigned int hp_ntimer; unsigned int hp_which; struct hpet_dev hp_dev[1]; }; static struct hpets *hpets; #define HPET_OPEN 0x0001 #define HPET_IE 0x0002 /* interrupt enabled */ #define HPET_PERIODIC 0x0004 #if BITS_PER_LONG == 64 #define write_counter(V, MC) writeq(V, MC) #define read_counter(MC) readq(MC) #else #define write_counter(V, MC) writel(V, MC) #define read_counter(MC) readl(MC) #endif #ifndef readq static inline unsigned long long readq(void __iomem *addr) { return readl(addr) | (((unsigned long long)readl(addr + 4)) << 32LL); } #endif #ifndef writeq static inline void writeq(unsigned long long v, void __iomem *addr) { writel(v & 0xffffffff, addr); writel(v >> 32, addr + 4); } #endif static irqreturn_t hpet_interrupt(int irq, void *data, struct pt_regs *regs) { struct hpet_dev *devp; unsigned long isr; devp = data; spin_lock(&hpet_lock); devp->hd_irqdata++; /* * For non-periodic timers, increment the accumulator. * This has the effect of treating non-periodic like periodic. */ if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) { unsigned long m, t; t = devp->hd_ireqfreq; m = read_counter(&devp->hd_hpet->hpet_mc); write_counter(t + m + devp->hd_hpets->hp_delta, &devp->hd_timer->hpet_compare); } isr = (1 << (devp - devp->hd_hpets->hp_dev)); writeq(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); return IRQ_HANDLED; } static int hpet_open(struct inode *inode, struct file *file) { struct hpet_dev *devp; struct hpets *hpetp; int i; if (file->f_mode & FMODE_WRITE) return -EINVAL; spin_lock_irq(&hpet_lock); 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) continue; else { devp = &hpetp->hp_dev[i]; break; } if (!devp) { spin_unlock_irq(&hpet_lock); return -EBUSY; } file->private_data = devp; devp->hd_irqdata = 0; devp->hd_flags |= HPET_OPEN; spin_unlock_irq(&hpet_lock); return 0; } static ssize_t hpet_read(struct file *file, char __user *buf, size_t count, loff_t * ppos) { DECLARE_WAITQUEUE(wait, current); unsigned long data; ssize_t retval; struct hpet_dev *devp; devp = file->private_data; if (!devp->hd_ireqfreq) return -EIO; if (count < sizeof(unsigned long)) return -EINVAL; add_wait_queue(&devp->hd_waitqueue, &wait); for ( ; ; ) { set_current_state(TASK_INTERRUPTIBLE); spin_lock_irq(&hpet_lock); data = devp->hd_irqdata; devp->hd_irqdata = 0; spin_unlock_irq(&hpet_lock); if (data) break; else if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; goto out; } else if (signal_pending(current)) { retval = -ERESTARTSYS; goto out; } schedule(); } retval = put_user(data, (unsigned long __user *)buf); if (!retval) retval = sizeof(unsigned long); out: __set_current_state(TASK_RUNNING); remove_wait_queue(&devp->hd_waitqueue, &wait); return retval; } static unsigned int hpet_poll(struct file *file, poll_table * wait) { unsigned long v; struct hpet_dev *devp; devp = file->private_data; if (!devp->hd_ireqfreq) return 0; poll_wait(file, &devp->hd_waitqueue, wait); spin_lock_irq(&hpet_lock); v = devp->hd_irqdata; spin_unlock_irq(&hpet_lock); if (v != 0) return POLLIN | POLLRDNORM; return 0; } static int hpet_mmap(struct file *file, struct vm_area_struct *vma) { #ifdef CONFIG_HPET_MMAP struct hpet_dev *devp; unsigned long addr; if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff) return -EINVAL; devp = file->private_data; addr = devp->hd_hpets->hp_hpet_phys; if (addr & (PAGE_SIZE - 1)) return -ENOSYS; vma->vm_flags |= VM_IO; vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT, PAGE_SIZE, vma->vm_page_prot)) { printk(KERN_ERR "remap_pfn_range failed in hpet.c\n"); return -EAGAIN; } return 0; #else return -ENOSYS; #endif } static int hpet_fasync(int fd, struct file *file, int on) { struct hpet_dev *devp; devp = file->private_data; if (fasync_helper(fd, file, on, &devp->hd_async_queue) >= 0) return 0; else return -EIO; } static int hpet_release(struct inode *inode, struct file *file) { struct hpet_dev *devp; struct hpet_timer __iomem *timer; int irq = 0; devp = file->private_data; timer = devp->hd_timer; spin_lock_irq(&hpet_lock); writeq((readq(&timer->hpet_config) & ~Tn_INT_ENB_CNF_MASK), &timer->hpet_config); irq = devp->hd_irq; devp->hd_irq = 0; devp->hd_ireqfreq = 0; if (devp->hd_flags & HPET_PERIODIC && readq(&timer->hpet_config) & Tn_TYPE_CNF_MASK) { unsigned long v; v = readq(&timer->hpet_config); v ^= Tn_TYPE_CNF_MASK; writeq(v, &timer->hpet_config); } devp->hd_flags &= ~(HPET_OPEN | HPET_IE | HPET_PERIODIC); spin_unlock_irq(&hpet_lock); if (irq) free_irq(irq, devp); if (file->f_flags & FASYNC) hpet_fasync(-1, file, 0); file->private_data = NULL; return 0; } static int hpet_ioctl_common(struct hpet_dev *, int, unsigned long, int); static int hpet_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { struct hpet_dev *devp; devp = file->private_data; return hpet_ioctl_common(devp, cmd, arg, 0); } static int hpet_ioctl_ieon(struct hpet_dev *devp) { struct hpet_timer __iomem *timer; struct hpet __iomem *hpet; struct hpets *hpetp; int irq; unsigned long g, v, t, m; unsigned long flags, isr; timer = devp->hd_timer; hpet = devp->hd_hpet; hpetp = devp->hd_hpets; if (!devp->hd_ireqfreq) return -EIO; spin_lock_irq(&hpet_lock); if (devp->hd_flags & HPET_IE) { spin_unlock_irq(&hpet_lock); return -EBUSY; } devp->hd_flags |= HPET_IE; spin_unlock_irq(&hpet_lock); irq = devp->hd_hdwirq; if (irq) { sprintf(devp->hd_name, "hpet%d", (int)(devp - hpetp->hp_dev)); if (request_irq (irq, hpet_interrupt, SA_INTERRUPT, devp->hd_name, (void *)devp)) { printk(KERN_ERR "hpet: IRQ %d is not free\n", irq); irq = 0; } } if (irq == 0) { spin_lock_irq(&hpet_lock); devp->hd_flags ^= HPET_IE; spin_unlock_irq(&hpet_lock); return -EIO; } devp->hd_irq = irq; t = devp->hd_ireqfreq; v = readq(&timer->hpet_config); g = v | Tn_INT_ENB_CNF_MASK; if (devp->hd_flags & HPET_PERIODIC) { write_counter(t, &timer->hpet_compare); g |= Tn_TYPE_CNF_MASK; v |= Tn_TYPE_CNF_MASK; writeq(v, &timer->hpet_config); v |= Tn_VAL_SET_CNF_MASK; writeq(v, &timer->hpet_config); local_irq_save(flags); m = read_counter(&hpet->hpet_mc); write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare); } else { local_irq_save(flags); m = read_counter(&hpet->hpet_mc); write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare); } isr = (1 << (devp - hpets->hp_dev)); writeq(isr, &hpet->hpet_isr); writeq(g, &timer->hpet_config); local_irq_restore(flags); return 0; } /* converts Hz to number of timer ticks */ static inline unsigned long hpet_time_div(struct hpets *hpets, unsigned long dis) { unsigned long long m; m = hpets->hp_tick_freq + (dis >> 1); do_div(m, dis); return (unsigned long)m; } static int hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel) { struct hpet_timer __iomem *timer; struct hpet __iomem *hpet; struct hpets *hpetp; int err; unsigned long v; switch (cmd) { case HPET_IE_OFF: case HPET_INFO: case HPET_EPI: case HPET_DPI: case HPET_IRQFREQ: timer = devp->hd_timer; hpet = devp->hd_hpet; hpetp = devp->hd_hpets; break; case HPET_IE_ON: return hpet_ioctl_ieon(devp); default: return -EINVAL; } err = 0; switch (cmd) { case HPET_IE_OFF: if ((devp->hd_flags & HPET_IE) == 0) break; v = readq(&timer->hpet_config); v &= ~Tn_INT_ENB_CNF_MASK; writeq(v, &timer->hpet_config); if (devp->hd_irq) { free_irq(devp->hd_irq, devp); devp->hd_irq = 0; } devp->hd_flags ^= HPET_IE; break; case HPET_INFO: { struct hpet_info info; info.hi_ireqfreq = hpet_time_div(hpetp, devp->hd_ireqfreq); info.hi_flags = readq(&timer->hpet_config) & Tn_PER_INT_CAP_MASK; info.hi_hpet = devp->hd_hpets->hp_which; info.hi_timer = devp - devp->hd_hpets->hp_dev; if (copy_to_user((void __user *)arg, &info, sizeof(info))) err = -EFAULT; break; } case HPET_EPI: v = readq(&timer->hpet_config); if ((v & Tn_PER_INT_CAP_MASK) == 0) { err = -ENXIO; break; } devp->hd_flags |= HPET_PERIODIC; break; case HPET_DPI: v = readq(&timer->hpet_config); if ((v & Tn_PER_INT_CAP_MASK) == 0) { err = -ENXIO; break; } if (devp->hd_flags & HPET_PERIODIC && readq(&timer->hpet_config) & Tn_TYPE_CNF_MASK) { v = readq(&timer->hpet_config); v ^= Tn_TYPE_CNF_MASK; writeq(v, &timer->hpet_config); } devp->hd_flags &= ~HPET_PERIODIC; break; case HPET_IRQFREQ: if (!kernel && (arg > hpet_max_freq) && !capable(CAP_SYS_RESOURCE)) { err = -EACCES; break; } if (!arg) { err = -EINVAL; break; } devp->hd_ireqfreq = hpet_time_div(hpetp, arg); } return err; } static struct file_operations hpet_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .read = hpet_read, .poll = hpet_poll, .ioctl = hpet_ioctl, .open = hpet_open, .release = hpet_release, .fasync = hpet_fasync, .mmap = hpet_mmap, }; EXPORT_SYMBOL(hpet_alloc); EXPORT_SYMBOL(hpet_register); EXPORT_SYMBOL(hpet_unregister); EXPORT_SYMBOL(hpet_control); int hpet_register(struct hpet_task *tp, int periodic) { unsigned int i; u64 mask; struct hpet_timer __iomem *timer; struct hpet_dev *devp; struct hpets *hpetp; switch (periodic) { case 1: mask = Tn_PER_INT_CAP_MASK; break; case 0: mask = 0; break; default: return -EINVAL; } spin_lock_irq(&hpet_task_lock); spin_lock(&hpet_lock); for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next) for (timer = hpetp->hp_hpet->hpet_timers, i = 0; i < hpetp->hp_ntimer; i++, timer++) { if ((readq(&timer->hpet_config) & Tn_PER_INT_CAP_MASK) != mask) continue; devp = &hpetp->hp_dev[i]; if (devp->hd_flags & HPET_OPEN || devp->hd_task) { devp = NULL; continue; } tp->ht_opaque = devp; devp->hd_task = tp; break; } spin_unlock(&hpet_lock); spin_unlock_irq(&hpet_task_lock); if (tp->ht_opaque) return 0; else return -EBUSY; } 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; } 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; } int hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg) { struct hpet_dev *devp; int err; if ((err = hpet_tpcheck(tp))) return err; spin_lock_irq(&hpet_lock); devp = tp->ht_opaque; if (devp->hd_task != tp) { spin_unlock_irq(&hpet_lock); return -ENXIO; } spin_unlock_irq(&hpet_lock); return hpet_ioctl_common(devp, cmd, arg, 1); } static ctl_table hpet_table[] = { { .ctl_name = 1, .procname = "max-user-freq", .data = &hpet_max_freq, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec, }, {.ctl_name = 0} }; static ctl_table hpet_root[] = { { .ctl_name = 1, .procname = "hpet", .maxlen = 0, .mode = 0555, .child = hpet_table, }, {.ctl_name = 0} }; static ctl_table dev_root[] = { { .ctl_name = CTL_DEV, .procname = "dev", .maxlen = 0, .mode = 0555, .child = hpet_root, }, {.ctl_name = 0} }; static struct ctl_table_header *sysctl_header; static void hpet_register_interpolator(struct hpets *hpetp) { #ifdef CONFIG_TIME_INTERPOLATION struct time_interpolator *ti; ti = kmalloc(sizeof(*ti), GFP_KERNEL); if (!ti) return; memset(ti, 0, sizeof(*ti)); ti->source = TIME_SOURCE_MMIO64; ti->shift = 10; ti->addr = &hpetp->hp_hpet->hpet_mc; ti->frequency = hpetp->hp_tick_freq; ti->drift = HPET_DRIFT; ti->mask = -1; hpetp->hp_interpolator = ti; register_time_interpolator(ti); #endif } /* * Adjustment for when arming the timer with * initial conditions. That is, main counter * ticks expired before interrupts are enabled. */ #define TICK_CALIBRATE (1000UL) static unsigned long hpet_calibrate(struct hpets *hpetp) { struct hpet_timer __iomem *timer = NULL; unsigned long t, m, count, i, flags, start; struct hpet_dev *devp; int j; struct hpet __iomem *hpet; for (j = 0, devp = hpetp->hp_dev; j < hpetp->hp_ntimer; j++, devp++) if ((devp->hd_flags & HPET_OPEN) == 0) { timer = devp->hd_timer; break; } if (!timer) return 0; hpet = hpets->hp_hpet; t = read_counter(&timer->hpet_compare); i = 0; count = hpet_time_div(hpetp, TICK_CALIBRATE); local_irq_save(flags); start = read_counter(&hpet->hpet_mc); do { m = read_counter(&hpet->hpet_mc); write_counter(t + m + hpetp->hp_delta, &timer->hpet_compare); } while (i++, (m - start) < count); local_irq_restore(flags); return (m - start) / i; } int hpet_alloc(struct hpet_data *hdp) { u64 cap, mcfg; struct hpet_dev *devp; u32 i, ntimer; struct hpets *hpetp; size_t siz; struct hpet __iomem *hpet; static struct hpets *last = (struct hpets *)0; unsigned long ns, period; unsigned long long temp; /* * hpet_alloc can be called by platform dependent code. * if platform dependent code has allocated the hpet * ACPI also reports hpet, then we catch it here. */ for (hpetp = hpets; hpetp; hpetp = hpetp->hp_next) if (hpetp->hp_hpet == hdp->hd_address) return 0; siz = sizeof(struct hpets) + ((hdp->hd_nirqs - 1) * sizeof(struct hpet_dev)); hpetp = kmalloc(siz, GFP_KERNEL); if (!hpetp) return -ENOMEM; memset(hpetp, 0, siz); hpetp->hp_which = hpet_nhpet++; hpetp->hp_hpet = hdp->hd_address; hpetp->hp_hpet_phys = hdp->hd_phys_address; hpetp->hp_ntimer = hdp->hd_nirqs; for (i = 0; i < hdp->hd_nirqs; i++) hpetp->hp_dev[i].hd_hdwirq = hdp->hd_irq[i]; hpet = hpetp->hp_hpet; cap = readq(&hpet->hpet_cap); ntimer = ((cap & HPET_NUM_TIM_CAP_MASK) >> HPET_NUM_TIM_CAP_SHIFT) + 1; if (hpetp->hp_ntimer != ntimer) { printk(KERN_WARNING "hpet: number irqs doesn't agree" " with number of timers\n"); kfree(hpetp); return -ENODEV; } if (last) last->hp_next = hpetp; else hpets = hpetp; last = hpetp; period = (cap & HPET_COUNTER_CLK_PERIOD_MASK) >> HPET_COUNTER_CLK_PERIOD_SHIFT; /* fs, 10^-15 */ temp = 1000000000000000uLL; /* 10^15 femtoseconds per second */ temp += period >> 1; /* round */ do_div(temp, period); hpetp->hp_tick_freq = temp; /* ticks per second */ printk(KERN_INFO "hpet%d: at MMIO 0x%lx, IRQ%s", hpetp->hp_which, hdp->hd_phys_address, hpetp->hp_ntimer > 1 ? "s" : ""); for (i = 0; i < hpetp->hp_ntimer; i++) printk("%s %d", i > 0 ? "," : "", hdp->hd_irq[i]); printk("\n"); ns = period / 1000000; /* convert to nanoseconds, 10^-9 */ printk(KERN_INFO "hpet%d: %ldns tick, %d %d-bit timers\n", hpetp->hp_which, ns, hpetp->hp_ntimer, cap & HPET_COUNTER_SIZE_MASK ? 64 : 32); mcfg = readq(&hpet->hpet_config); if ((mcfg & HPET_ENABLE_CNF_MASK) == 0) { write_counter(0L, &hpet->hpet_mc); mcfg |= HPET_ENABLE_CNF_MASK; writeq(mcfg, &hpet->hpet_config); } for (i = 0, devp = hpetp->hp_dev; i < hpetp->hp_ntimer; i++, devp++) { struct hpet_timer __iomem *timer; timer = &hpet->hpet_timers[devp - hpetp->hp_dev]; devp->hd_hpets = hpetp; devp->hd_hpet = hpet; devp->hd_timer = timer; /* * If the timer was reserved by platform code, * then make timer unavailable for opens. */ if (hdp->hd_state & (1 << i)) { devp->hd_flags = HPET_OPEN; continue; } init_waitqueue_head(&devp->hd_waitqueue); } hpetp->hp_delta = hpet_calibrate(hpetp); hpet_register_interpolator(hpetp); return 0; } static acpi_status hpet_resources(struct acpi_resource *res, void *data) { struct hpet_data *hdp; acpi_status status; struct acpi_resource_address64 addr; struct hpets *hpetp; hdp = data; status = acpi_resource_to_address64(res, &addr); if (ACPI_SUCCESS(status)) { unsigned long size; size = addr.max_address_range - addr.min_address_range + 1; hdp->hd_phys_address = addr.min_address_range; hdp->hd_address = ioremap(addr.min_address_range, size); for (hpetp = hpets; hpetp; hpetp = hpetp->hp_next) if (hpetp->hp_hpet == hdp->hd_address) return -EBUSY; } else if (res->id == ACPI_RSTYPE_EXT_IRQ) { struct acpi_resource_ext_irq *irqp; int i; irqp = &res->data.extended_irq; if (irqp->number_of_interrupts > 0) { hdp->hd_nirqs = irqp->number_of_interrupts; for (i = 0; i < hdp->hd_nirqs; i++) { int rc = acpi_register_gsi(irqp->interrupts[i], irqp->edge_level, irqp->active_high_low); if (rc < 0) return AE_ERROR; hdp->hd_irq[i] = rc; } } } return AE_OK; } static int hpet_acpi_add(struct acpi_device *device) { acpi_status result; struct hpet_data data; memset(&data, 0, sizeof(data)); result = acpi_walk_resources(device->handle, METHOD_NAME__CRS, hpet_resources, &data); if (ACPI_FAILURE(result)) return -ENODEV; if (!data.hd_address || !data.hd_nirqs) { printk("%s: no address or irqs in _CRS\n", __FUNCTION__); return -ENODEV; } return hpet_alloc(&data); } static int hpet_acpi_remove(struct acpi_device *device, int type) { /* XXX need to unregister interpolator, dealloc mem, etc */ return -EINVAL; } static struct acpi_driver hpet_acpi_driver = { .name = "hpet", .ids = "PNP0103", .ops = { .add = hpet_acpi_add, .remove = hpet_acpi_remove, }, }; static struct miscdevice hpet_misc = { HPET_MINOR, "hpet", &hpet_fops }; static int __init hpet_init(void) { int result; result = misc_register(&hpet_misc); if (result < 0) return -ENODEV; sysctl_header = register_sysctl_table(dev_root, 0); result = acpi_bus_register_driver(&hpet_acpi_driver); if (result < 0) { if (sysctl_header) unregister_sysctl_table(sysctl_header); misc_deregister(&hpet_misc); return result; } return 0; } static void __exit hpet_exit(void) { acpi_bus_unregister_driver(&hpet_acpi_driver); if (sysctl_header) unregister_sysctl_table(sysctl_header); misc_deregister(&hpet_misc); return; } module_init(hpet_init); module_exit(hpet_exit); MODULE_AUTHOR("Bob Picco "); MODULE_LICENSE("GPL");