/* 
 * Copyright 2010 Stefan Lankes, Chair for Operating Systems,
 *                               RWTH Aachen University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This file is part of MetalSVM.
 */

#include <metalsvm/stddef.h>
#include <metalsvm/stdio.h>
#include <metalsvm/string.h>
#include <metalsvm/errno.h>
#include <metalsvm/processor.h>
#include <metalsvm/time.h>
#include <asm/irq.h>
#include <asm/irqflags.h>
#include <asm/apic.h>
#include <asm/multiboot.h>

#define MP_FLT_SIGNATURE	0x5f504d5f

#define APIC_VERSION		0x0030	// Local APIC Version Register
#define APIC_TPR		0x0080	// Task Priority Regster
#define APIC_EOI		0x00B0	// EOI Register
#define APIC_SVR		0x00F0	// Spurious Interrupt Vector Register
#define APIC_LVT_T		0x0320	// LVT Thermal Sensor Register (P4/Xeon only)
#define APIC_LVT_PMC		0x0340	// LVT Performance Monitoring Counters Register
#define APIC_LINT0		0x0350	// LVT LINT0 Register
#define APIC_LINT1		0x0360	// LVT LINT1 Register
#define APIC_LVT_ER		0x0370	// LVT Error Register
#define APIC_ICR		0x0380	// Initial Count Register
#define APIC_CCR		0x0390	// Current Count Register
#define APIC_DCR		0x03E0	// Divide Configuration Register

static apic_mp_t* apic_mp = NULL;
static apic_config_table_t* apic_config = NULL;
static uint32_t ncores = 1;

#ifndef CONFIG_MULTIBOOT
static unsigned int* search_apic(unsigned int base, unsigned int limit) {
	unsigned int *ptr;

	for (ptr = (unsigned int *) base; (unsigned int) ptr < limit; ptr++) {
		if (*ptr == MP_FLT_SIGNATURE)
			return ptr;
        }

	return NULL;
}
#endif

/*
 * Send a 'End of Interrupt' command to the APIC
 */
void apic_eoi(void)
{
	*((uint32_t*) (apic_config->lapic+APIC_EOI)) = 0;
}

/* 
 * detects the timer frequency of the APIC and restart
 * the APIC timer with the correct period
 */
int apic_calibration(void)
{
	uint64_t ticks, old;
	uint32_t diff;

	if (!has_apic())
		return -ENXIO;

	old = get_clock_tick();

	/* wait for the next time slice */
	while((ticks = get_clock_tick()) - old == 0)
		;
	
	*((uint32_t*) (apic_config->lapic+APIC_DCR)) = 0xB;		// set it to 1 clock increments
	*((uint32_t*) (apic_config->lapic+APIC_LVT_T)) = 0x20030;	// connects the timer to 48 and enables it
	*((uint32_t*) (apic_config->lapic+APIC_ICR)) = 0xFFFFFFFF;

	/* wait 3 time slices to determine a ICR */
	while(get_clock_tick() - ticks < 3)
		;

	diff = 0xFFFFFFFF - *((uint32_t*) (apic_config->lapic+APIC_CCR));

	*((uint32_t*) (apic_config->lapic+APIC_DCR)) = 0xB;		// set it to 1 clock increments
	*((uint32_t*) (apic_config->lapic+APIC_LVT_T)) = 0x20030;	// connects the timer to 48 and enables it
	*((uint32_t*) (apic_config->lapic+APIC_ICR)) = diff / 3;

	// Now, MetalSVM is able to use the APIC => Therefore, we disable the PIC
	outportb(0xA1, 0xFF);
	outportb(0x21, 0xFF);

	return 0;
}

static int apic_probe(void)
{
	size_t addr;
	uint32_t i, count;

	// searching MP signature in the reserved memory areas
#ifdef CONFIG_MULTIBOOT
	if (mb_info && (mb_info->flags & (1 << 6))) {
 		multiboot_memory_map_t* mmap = (multiboot_memory_map_t*) mb_info->mmap_addr;
		multiboot_memory_map_t* mmap_end = (void*) ((size_t) mb_info->mmap_addr + mb_info->mmap_length);

		while (mmap < mmap_end) {
			if (mmap->type == MULTIBOOT_MEMORY_RESERVED) {
				addr = mmap->addr;

				for(i=0; i<mmap->len; i++, addr++) {
					if (strncmp((void*)addr, "_MP_", 4) == 0) {
						apic_mp = (apic_mp_t*) addr;
						goto found_mp;
					}
				}
				
			}
			mmap++;
		}
	}
#else
	apic_mp = (apic_mp_t*) search_apic(0xF0000, 0x100000);
	if (!apic_mp)
		apic_mp = (apic_mp_t*) search_apic(0x9F000, 0xA0000);
#endif
found_mp:

	if (!apic_mp) 
		goto out;

	kprintf("System uses Multiprocessing Specification 1.%d\n", apic_mp->version);	
	kprintf("MP features 1: %d\n", apic_mp->features[0]);

	if (apic_mp->features[0]) {
		kputs("Currently, MetalSVM supports only multiprocessing via the MP config tables!\n");
		goto out;
	}

	apic_config = (apic_config_table_t*) apic_mp->mp_config;
	if (!apic_config || strncmp((void*) &apic_config->signature, "PCMP", 4) !=0) {
		kputs("Invalid MP config table\n");
		goto out;
	}

	addr = (size_t) apic_config;
	addr += sizeof(apic_config_table_t);
	if (addr % 4)
		addr += 4 - addr % 4;

	for(i=0, count=0; i<apic_config->entry_count; i++) {
		if (*((uint8_t*) addr) == 0) {
			count++;
			addr += 20;
		} else addr += 8;
	}
	kprintf("Found %d cores\n", count);

	if (count > MAX_CORES) {
		kputs("Found too many cores! Increase the macro MAX_CORES!\n");
		goto out;
	}
	ncores = count;

	i = *((uint32_t*) (apic_config->lapic+APIC_VERSION));
	kprintf("Found APIC at 0x%x\n", apic_config->lapic);
	kprintf("Maximum LVT Entry: 0x%x\n", (i >> 16) & 0xFF);
	kprintf("APIC Version: 0x%x\n", i & 0xFF);

	cpuid(0x1, &i);
	if (!(i & (1 << 5))) {
		kputs("Unable to use Machine-Specific Registers (MSR)\n");
		goto out;
	}

	if (!(rdmsr(0x1B) & (1 << 11))) {
		kputs("Unable to use APIC Global Enable flag!\n");
		goto out;
	}

	return 0;

out:
	apic_mp = NULL;
	apic_config = NULL;
	ncores = 1;

	return -ENXIO;
}

int apic_init(void)
{ 
	int ret;
	
	ret = apic_probe();
	if (!ret)
		return ret;

	*((uint32_t*) (apic_config->lapic+APIC_TPR)) = 0x20;		// inhibit softint delivery
	*((uint32_t*) (apic_config->lapic+APIC_LVT_T)) = 0x10000;	// disable timer interrupt
	*((uint32_t*) (apic_config->lapic+APIC_LVT_PMC)) = 0x10000;	// disable performance counter interrupt
	*((uint32_t*) (apic_config->lapic+APIC_LINT0)) = 0x31;		// connect LINT0 to idt entry 49
	*((uint32_t*) (apic_config->lapic+APIC_LINT1)) = 0x32;		// connect LINT1 to idt entry 50
	*((uint32_t*) (apic_config->lapic+APIC_LVT_ER)) = 0x33;		// connect error to idt entry 51
	*((uint32_t*) (apic_config->lapic+APIC_SVR)) = 0x134;		// enable the apic and connect to the idt entry 52	

	return 0;
}

int has_apic(void)
{
	return ((apic_mp != NULL) && (apic_config != NULL));
}