/*
 * Copyright 2008, Dustin Howett, dustin.howett@gmail.com. All rights reserved.
 * Distributed under the terms of the MIT License.
 */
#ifndef _KERNEL_ARCH_x86_HPET_H
#define _KERNEL_ARCH_x86_HPET_H

#include <arch/x86/arch_acpi.h>

/* All masks are 32 bits wide to represent relative bit locations */
/* Doing it this way is Required since the HPET only supports 32/64-bit aligned reads. */

/* Global Capability Register Masks */
#define HPET_CAP_MASK_ID			0x000000FF
#define HPET_CAP_MASK_NUMTIMERS			0x00001F00
#define HPET_CAP_MASK_WIDTH			0x00002000
#define HPET_CAP_MASK_LEGACY			0x00008000
#define HPET_CAP_MASK_VENDOR_ID			0xFFFF0000

/* Retrieve Global Capabilities */
#define HPET_GET_ID(regs)		((regs)->capability & HPET_CAP_MASK_ID)
#define HPET_GET_NUM_TIMERS(regs)	(((regs)->capability & HPET_CAP_MASK_NUMTIMERS) >> 8)
#define HPET_IS_64BIT(regs)		(((regs)->capability & HPET_CAP_MASK_WIDTH) >> 13)
#define HPET_IS_LEGACY_CAPABLE(regs)	(((regs)->capability & HPET_CAP_MASK_LEGACY) >> 15)
#define HPET_GET_VENDOR_ID(regs)	(((regs)->capability & HPET_CAP_MASK_VENDOR_ID) >> 16)

/* Global Config Register Masks */
#define HPET_CONF_MASK_ENABLED			0x00000001
#define HPET_CONF_MASK_LEGACY			0x00000002

/* Retrieve Global Configuration */
#define HPET_IS_ENABLED(regs)		((regs)->config & HPET_CONF_MASK_ENABLED)
#define HPET_IS_LEGACY(regs)		(((regs)->config & HPET_CONF_MASK_LEGACY) >> 1)

#define ACPI_HPET_SIGNATURE			"HPET"

struct hpet_timer {
	/* Timer Configuration/Capability bits, Reversed because x86 is LSB */
	volatile uint32 config;
	volatile uint32 interrupts;		/* Each bit represents one allowed interrupt for this timer. */
					/* Read Only. If interrupt 16 is allowed, bit 16 will be 1. */

	volatile uint64 comparator;		/* Comparator value */
					/* non-periodic mode: fires once when main counter = this comparator */
					/* periodic mode: fires when timer reaches this value, is increased by the original value */

	/* FSB Interrupt Route values */
	volatile uint32 fsb_value;
	volatile uint32 fsb_addr;		/* Where fsb_value should be written */

	volatile uint64 reserved;
};


struct hpet_regs {
	/* Capability bits */
	volatile uint32 period;
	volatile uint32 capability;			/* Capabilities */

	volatile uint64 reserved1;

	/* Config Bits */
	volatile uint64 config;

	volatile uint64 reserved2;

	/* Interrupt Status bits */
	volatile uint64 timer_interrupts;	/* Interrupt Config bits for timers 0-31 */
					/* Level Tigger: 0 = off, 1 = set by hardware, timer is active */
					/* Edge Trigger: ignored */
					/* Writing 0 will not clear these. Must write 1 again. */

	volatile uint8 reserved3[200];

	volatile uint64 counter;

	volatile uint64 reserved4;

	volatile struct hpet_timer timer0;
	volatile struct hpet_timer timer1;
	volatile struct hpet_timer timer2;
};


typedef struct acpi_hpet {
	acpi_descriptor_header	header;	/* "HPET" signature and acpi header */
	uint16	vendor_id;
	uint8	legacy_capable : 1;
	uint8	reserved1 : 1;
	uint8	countersize : 1;
	uint8	comparators : 5;
	uint8	hw_revision;
	struct hpet_addr {
		uint8	address_space;
		uint8	register_width;
		uint8	register_offset;
		uint8	reserved;
		uint64	address;
	} hpet_address;
	uint8	number;
	uint16	min_tick;
} _PACKED acpi_hpet;

#endif