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141 lines
4.0 KiB
C
141 lines
4.0 KiB
C
#include <amd64/hpet.h>
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#include <libk/std.h>
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#include <limine/requests.h>
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#include <sync/spin_lock.h>
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#include <sys/debug.h>
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#include <sys/mm.h>
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#include <sys/spin.h>
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#include <uacpi/acpi.h>
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#include <uacpi/status.h>
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#include <uacpi/tables.h>
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#include <uacpi/uacpi.h>
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/*
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* HPET (High Precision Event Timer) driver code. See more at https://wiki.osdev.org/HPET
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*/
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/* HPET Main Counter Value Register */
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#define HPET_MCVR 0xF0
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/* HPET General Configuration Register */
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#define HPET_GCR 0x10
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/* HPET General Capabilities and ID Register */
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#define HPET_GCIDR 0x00
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/* Set whether we sould use 32-bit or 64-bit reads/writes */
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static bool hpet_32bits = 1;
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/* Physical address for HPET MMIO */
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static uintptr_t hpet_paddr;
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/* HPET period in femtoseconds */
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static uint64_t hpet_period_fs;
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/* Lock, which protects concurrent access. See amd64/smp.c */
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static spin_lock_t hpet_lock = SPIN_LOCK_INIT;
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/* Read a HPET register. Assumes caller holds hpet_lock */
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static uint64_t amd64_hpet_read64 (uint32_t reg) {
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struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
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uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
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return *(volatile uint64_t*)(hpet_vaddr + reg);
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}
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static uint32_t amd64_hpet_read32 (uint32_t reg) {
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struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
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uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
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return *(volatile uint32_t*)(hpet_vaddr + reg);
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}
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/* Write a HPET register. Assumes caller holds hpet_lock */
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static void amd64_hpet_write64 (uint32_t reg, uint64_t value) {
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struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
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uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
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*(volatile uint64_t*)(hpet_vaddr + reg) = value;
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}
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static void amd64_hpet_write32 (uint32_t reg, uint32_t value) {
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struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
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uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
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*(volatile uint32_t*)(hpet_vaddr + reg) = value;
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}
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/* Read current value of HPET_MCVR register. */
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static uint64_t amd64_hpet_read_counter (void) {
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uint64_t value;
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spin_lock (&hpet_lock);
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if (!hpet_32bits)
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value = amd64_hpet_read64 (HPET_MCVR);
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else {
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uint32_t hi1, lo, hi2;
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do {
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hi1 = amd64_hpet_read32 (HPET_MCVR + 4);
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lo = amd64_hpet_read32 (HPET_MCVR + 0);
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hi2 = amd64_hpet_read32 (HPET_MCVR + 4);
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} while (hi1 != hi2);
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value = ((uint64_t)hi1 << 32) | lo;
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}
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spin_unlock (&hpet_lock);
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return value;
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}
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static void amd64_hpet_write_counter (uint64_t value) {
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spin_lock (&hpet_lock);
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if (!hpet_32bits)
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amd64_hpet_write64 (HPET_MCVR, value);
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else {
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amd64_hpet_write32 (HPET_MCVR, (uint32_t)value);
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amd64_hpet_write32 (HPET_MCVR + 4, (uint32_t)(value >> 32));
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}
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spin_unlock (&hpet_lock);
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}
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/* Sleep for a given amount of microseconds. This time can last longer due to \ref hpet_lock being
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* held. */
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void amd64_hpet_sleep_micro (uint64_t us) {
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if (hpet_period_fs == 0)
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return;
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uint64_t ticks_to_wait = (us * 1000ULL) / (hpet_period_fs / 1000000ULL);
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uint64_t start = amd64_hpet_read_counter ();
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for (;;) {
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uint64_t now = amd64_hpet_read_counter ();
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if ((now - start) >= ticks_to_wait)
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break;
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__asm__ volatile ("pause" ::: "memory");
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}
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}
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/* Initialize HPET */
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void amd64_hpet_init (void) {
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struct uacpi_table hpet_table;
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uacpi_status status = uacpi_table_find_by_signature (ACPI_HPET_SIGNATURE, &hpet_table);
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if (status != UACPI_STATUS_OK) {
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DEBUG ("Could not find HPET table!\n");
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spin ();
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}
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struct acpi_hpet* hpet = (struct acpi_hpet*)hpet_table.virt_addr;
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hpet_paddr = (uintptr_t)hpet->address.address;
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struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
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mm_map_kernel_page (hpet_paddr, (uintptr_t)hhdm->offset + hpet_paddr,
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MM_PG_PRESENT | MM_PG_RW | MM_PD_RELOAD);
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uint64_t caps = amd64_hpet_read64 (HPET_GCIDR);
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hpet_32bits = (caps & (1 << 13)) ? 0 : 1;
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hpet_period_fs = (uint32_t)(caps >> 32);
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amd64_hpet_write64 (HPET_GCR, 0);
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amd64_hpet_write_counter (0);
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amd64_hpet_write64 (HPET_GCR, 1);
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}
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