Kernel: Add simple support for timer using TSC

4 files changed, 83 insertions, 3 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 45e898e..e6626d8 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,6 +1,6 @@
 CC="i686-sb-gcc"
 AS="i686-sb-as"
-OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o kubsan.o drivers/serial.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o elf.o ksbrk.o sched/scheduler.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o math.o signal.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o lib/ringbuffer.o lib/relist.o
+OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o kubsan.o drivers/serial.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o elf.o ksbrk.o sched/scheduler.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o math.o signal.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o lib/ringbuffer.o lib/relist.o arch/i386/tsc.o arch/i386/asm_tsc.o
 CFLAGS = -std=c99 -O0 -fsanitize=vla-bound,shift-exponent,pointer-overflow,shift,signed-integer-overflow,bounds -ggdb -ffreestanding -Wall -Wextra -Wno-int-conversion -Wno-unused-parameter -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
 LDFLAGS=
 INCLUDE=-I./includes/ -I../include/ -I./libc/include/
diff --git a/kernel/arch/i386/asm_tsc.s b/kernel/arch/i386/asm_tsc.s
new file mode 100644
index 0000000..963687e
--- /dev/null
+++ b/kernel/arch/i386/asm_tsc.s
@@ -0,0 +1,63 @@
+.intel_syntax noprefix
+
+.global get_tsc
+.global get_hz
+
+# 1.193182 MHz
+# So 0xFFFF is roughly 0.05492 seconds
+# So take the result times 18 and you got your Hz
+
+get_tsc:
+	rdtsc
+	ret
+
+get_hz:
+	cli
+	# Disable the gate for channel 2 so the clock can be set.
+	# This should only matter if the channel already has count
+	inb al, 0x61
+	and al, 0xFE
+	or al, 0x1
+	outb 0x61, al
+
+	# Set mode
+	mov al, 0b10110010
+	outb 0x43, al
+
+	# 0x2e9b = 11931 which is close to the PIT Hz divided by 100
+	mov al, 0x9b
+	outb 0x42, al
+	mov al, 0x2e
+	outb 0x42, al
+
+	rdtsc
+	mov ecx, eax
+	mov esi, edx
+
+	# Set the gate for channel 2
+	inb al, 0x61
+	or al, 0x1
+	outb 0x61, al
+
+	# The fifth bit will(seems to) flip when the count is low.
+	and al, 0x20
+	jnz none_zero_check
+
+zero_check:
+	inb al, 0x61
+	andb al, 0x20
+	cmp al, 0
+	jz zero_check
+	jmp end
+
+none_zero_check:
+	inb al, 0x61
+	andb al, 0x20
+	cmp al, 0
+	jnz none_zero_check
+end:
+	rdtsc
+
+	sub eax, ecx
+	sub edx, esi
+	ret
diff --git a/kernel/arch/i386/tsc.h b/kernel/arch/i386/tsc.h
new file mode 100644
index 0000000..2e29cf3
--- /dev/null
+++ b/kernel/arch/i386/tsc.h
@@ -0,0 +1,4 @@
+#include <typedefs.h>
+
+u64 get_tsc();
+u64 get_hz();
diff --git a/kernel/drivers/pit.c b/kernel/drivers/pit.c
index db9cd2a..ac4e555 100644
--- a/kernel/drivers/pit.c
+++ b/kernel/drivers/pit.c
@@ -1,4 +1,5 @@
 #include "pit.h"
+#include <arch/i386/tsc.h>
 
 #define PIT_IO_CHANNEL_0 0x40
 #define PIT_IO_MODE_COMMAND 0x43
@@ -8,8 +9,9 @@ u32 pit_counter = 0;
 u32 switch_counter = 0;
 u16 hertz;
 
+u64 cpu_mhz = 0;
 u64 pit_num_ms(void) {
-  return clock_num_ms_ticks;
+  return (get_tsc()) / (cpu_mhz * 1000);
 }
 
 u16 read_pit_count(void) {
@@ -24,6 +26,8 @@ u16 read_pit_count(void) {
 }
 
 void set_pit_count(u16 _hertz) {
+  cpu_mhz = get_hz() / 10000;
+
   hertz = _hertz;
   u16 divisor = 1193180 / hertz;
 
@@ -45,9 +49,18 @@ void set_pit_count(u16 _hertz) {
 
 int last_flush = 0;
 
+u64 last_tsc = 0;
+
 extern int is_switching_tasks;
 void int_clock(reg_t *regs) {
-  clock_num_ms_ticks += 5;
+  u64 current_tsc = get_tsc();
+
+  u64 delta = (current_tsc - last_tsc) / (cpu_mhz * 1000);
+
+  clock_num_ms_ticks += delta;
+
+  last_tsc = current_tsc;
+
   switch_counter++;
   if (clock_num_ms_ticks - last_flush > 50) {
     tcp_flush_acks();