coreboot-kgpe-d16/payloads/libpayload/arch/x86/apic.c

269 lines
6.8 KiB
C

/*
* This file is part of the libpayload project.
*
* Copyright 2018 Google LLC
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <libpayload.h>
#include <arch/apic.h>
#include <arch/cpuid.h>
#include <arch/msr.h>
#include <exception.h>
#define APIC_BASE_MSR 0x0000001B
#define APIC_BASE_MASK (0xFFFFFFFULL << 12)
#define CPUID_XAPIC_ENABLED_BIT (1 << 9)
#define CPUID_XAPIC2_ENABLED_BIT (1 << 21)
#define XAPIC_ENABLED_BIT (1 << 11)
#define X2APIC_ENABLED_BIT (1 << 10)
#define APIC_MASKED_BIT (1 << 16)
#define APIC_SW_ENABLED_BIT (1 << 8)
#define APIC_ID 0x020
#define APIC_ID_SHIFT 24
#define APIC_ID_MASK (0xFFUL << APIC_ID_SHIFT)
#define APIC_VERSION 0x030
#define APIC_MAX_LVT_SHIFT 16
#define APIC_MAX_LVT_MASK (0xFFUL << APIC_MAX_LVT_SHIFT)
#define APIC_TASK_PRIORITY 0x080
#define APIC_TASK_PRIORITY_MASK 0xFFUL
#define APIC_EOI 0x0B0
#define APIC_SPURIOUS 0x0F0
#define APIC_LVT_TIMER 0x320
#define APIC_TIMER_INIT_COUNT 0x380
#define APIC_TIMER_CUR_COUNT 0x390
#define APIC_TIMER_DIV_CFG 0x3E0
#define APIC_LVT_SIZE 0x010
#define APIC_TIMER_VECTOR 0x20
static uint32_t apic_bar;
static int _apic_initialized;
// TODO: Build a lookup table to avoid calculating it.
static uint32_t ticks_per_ms;
static volatile uint8_t timer_waiting;
enum APIC_CAPABILITY {
DISABLED = 0,
XACPI = 1 << 0,
X2ACPI = 1 << 1
};
int apic_initialized(void)
{
return _apic_initialized;
}
static inline uint32_t apic_read32(uint32_t offset)
{
return read32((void *)(apic_bar + offset));
}
static inline void apic_write32(uint32_t offset, uint32_t value)
{
write32((void *)(apic_bar + offset), value);
}
uint8_t apic_id(void)
{
die_if(!apic_bar, "APIC is not initialized");
uint8_t id =
(apic_read32(APIC_ID) & APIC_ID_MASK) >> APIC_ID_SHIFT;
return id;
}
void apic_delay(unsigned int usec)
{
die_if(!ticks_per_ms, "apic_init_timer was not run.");
die_if(timer_waiting, "timer already started.");
die_if(!interrupts_enabled(), "Interrupts disabled.");
/* The order is important so we don't underflow */
uint64_t ticks = usec * ticks_per_ms / USECS_PER_MSEC;
/* Not enough resolution */
if (!ticks)
return;
/* Disable interrupts so we don't get a race condition between
* starting the timer and the hlt instruction. */
disable_interrupts();
timer_waiting = 1;
apic_write32(APIC_TIMER_INIT_COUNT, ticks);
/* Loop in case another interrupt has fired and resumed execution. */
do {
asm volatile(
"sti\n\t"
"hlt\n\t"
/* Disable interrupts to prevent a race condition
* between checking timer_waiting and executing the hlt
* instruction again. */
"cli\n\t");
} while (timer_waiting);
/* Leave hardware interrupts enabled. */
enable_interrupts();
}
static void timer_interrupt_handler(u8 vector)
{
timer_waiting = 0;
}
void apic_eoi(void)
{
die_if(!apic_bar, "APIC is not initialized");
apic_write32(APIC_EOI, 0);
}
static enum APIC_CAPABILITY apic_capabilities(void)
{
uint32_t eax, ebx, ecx, edx;
cpuid(1, eax, ebx, ecx, edx);
enum APIC_CAPABILITY capabilities = DISABLED;
if (edx & CPUID_XAPIC_ENABLED_BIT)
capabilities |= XACPI;
if (ecx & CPUID_XAPIC2_ENABLED_BIT)
capabilities |= X2ACPI;
return capabilities;
}
static uint8_t apic_max_lvt_entries(void)
{
die_if(!apic_bar, "APIC is not initialized");
uint32_t reg = apic_read32(APIC_VERSION);
reg &= APIC_MAX_LVT_MASK;
reg >>= APIC_MAX_LVT_SHIFT;
return (uint8_t)reg;
}
static void apic_reset_all_lvts(void)
{
uint8_t max = apic_max_lvt_entries();
for (int i = 0; i <= max; ++i) {
uint32_t offset = APIC_LVT_TIMER + APIC_LVT_SIZE * i;
apic_write32(offset, APIC_MASKED_BIT);
}
}
static void apic_set_task_priority(uint8_t priority)
{
die_if(!apic_bar, "APIC is not initialized");
uint32_t tpr = apic_read32(APIC_TASK_PRIORITY);
tpr &= ~APIC_TASK_PRIORITY_MASK;
tpr |= priority;
apic_write32(APIC_TASK_PRIORITY, priority);
}
static void apic_init_timer(void)
{
die_if(!apic_bar, "APIC is not initialized");
apic_write32(APIC_LVT_TIMER, APIC_MASKED_BIT);
/* Divide the clock by 1. */
apic_write32(APIC_TIMER_DIV_CFG, 0xB);
/* Calibrate the APIC timer */
if (!ticks_per_ms) {
/* Set APIC init counter to MAX and count for 1 ms */
apic_write32(APIC_TIMER_INIT_COUNT, UINT32_MAX);
/* This is safe because apic_initialized() returns false so
* arch_ndelay() falls back to a busy loop. */
mdelay(1);
ticks_per_ms =
UINT32_MAX - apic_read32(APIC_TIMER_CUR_COUNT);
}
/* Clear the count so we don't get any stale interrupts */
apic_write32(APIC_TIMER_INIT_COUNT, 0);
/* Unmask the timer and set the vector. */
apic_write32(APIC_LVT_TIMER, APIC_TIMER_VECTOR);
}
static void apic_sw_enable(void)
{
uint32_t reg = apic_read32(APIC_SPURIOUS);
if (reg & APIC_SW_ENABLED_BIT)
return;
reg |= APIC_SW_ENABLED_BIT;
apic_write32(APIC_SPURIOUS, reg);
}
void apic_init(void)
{
uint64_t apic_bar_reg;
printf("APIC Init Started\n");
die_if(apic_initialized(), "APIC already initialized");
die_if(!(apic_capabilities() & XACPI), "APIC is not supported");
apic_bar_reg = _rdmsr(APIC_BASE_MSR);
die_if(!(apic_bar_reg & XAPIC_ENABLED_BIT), "APIC is not enabled");
die_if(apic_bar_reg & X2APIC_ENABLED_BIT,
"APIC is configured in x2APIC mode which is not supported");
apic_bar = (uint32_t)(apic_bar_reg & APIC_BASE_MASK);
apic_reset_all_lvts();
apic_set_task_priority(0);
apic_sw_enable();
apic_init_timer();
set_interrupt_handler(APIC_TIMER_VECTOR, &timer_interrupt_handler);
_apic_initialized = 1;
printf("APIC Configured\n");
}