path: root/drivers/char/hpet.c

/*
 * 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 <robert.picco@hp.com>
 *
 * 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 <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/smp_lock.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/major.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/wait.h>
#include <linux/bcd.h>
#include <linux/seq_file.h>
#include <linux/bitops.h>
#include <linux/clocksource.h>

#include <asm/current.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/div64.h>

#include <linux/acpi.h>
#include <acpi/acpi_bus.h>
#include <linux/hpet.h>

/*
 * The High Precision Event Timer driver.
 * This driver is closely modelled after the rtc.c driver.
 * http://www.intel.com/hardwaredesign/hpetspec_1.pdf
 */
#define	HPET_USER_FREQ	(64)
#define	HPET_DRIFT	(500)

#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)
#else
#define	write_counter(V, MC)	writel(V, MC)
#define	read_counter(MC)	readl(MC)
#endif

static u32 hpet_nhpet, hpet_max_freq = HPET_USER_FREQ;

/* This clocksource driver currently only works on ia64 */
#ifdef CONFIG_IA64
static void __iomem *hpet_mctr;

static cycle_t read_hpet(struct clocksource *cs)
{
	return (cycle_t)read_counter((void __iomem *)hpet_mctr);
}

static struct clocksource clocksource_hpet = {
        .name           = "hpet",
        .rating         = 250,
        .read           = read_hpet,
        .mask           = CLOCKSOURCE_MASK(64),
	.mult		= 0, /* to be calculated */
        .shift          = 10,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
};
static struct clocksource *hpet_clocksource;
#endif

/* A lock for concurrent access by app and isr hpet activity. */
static DEFINE_SPINLOCK(hpet_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;
	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 clocksource *hp_clocksource;
	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
#define	HPET_SHARED_IRQ		0x0008


#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 hpet_dev *devp;
	unsigned long isr;

	devp = data;
	isr = 1 << (devp - devp->hd_hpets->hp_dev);

	if ((devp->hd_flags & HPET_SHARED_IRQ) &&
	    !(isr & readl(&devp->hd_hpet->hpet_isr)))
		return IRQ_NONE;

	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