kernel: add standard clock system

arch/x86_64/acpi/apic.cpp

@@ -1,4 +1,5 @@
 #include <socks/printk.h>
+#include <socks/clock.h>
 #include <socks/vm.h>
 #include <socks/cpu.h>
 #include <arch/acpi/io_apic.hpp>
@@ -16,6 +17,7 @@
 #define IA32_APIC_BASE_MSR_ENABLE 0x800
 
 static int apic_enabled = 0;
+static unsigned int bsp_id = (unsigned int)-1;
 
 using namespace arch::acpi;
 
@@ -118,12 +120,26 @@ static void ioapic_init(uintptr_t base, unsigned int int_base)
 	queue_push_back(&io_apics, &apic->io_entry);
 }
 
+static int lapic_clock_irq(void)
+{
+	if (this_cpu() == bsp_id) {
+		clock_advance(1);
+	}
+
+	return 0;
+}
+
+static struct irq_hook lapic_clock_irq_hook = {
+	{},
+	lapic_clock_irq,
+};
+
 void local_apic_config_timer(void)
 {
 	local_apic lapic(lapic_base);
 	lapic.write(local_apic::TIMER_DIV, 0x3);
 	lapic.write(local_apic::TIMER_INITCOUNT, (uint32_t)-1);
-	pit_wait(100);
+	clock_wait(10);
 	lapic.write(local_apic::LVT_TIMER, APIC_LVT_INT_MASKED);
 
 	/* mask IRQ0 to block interrupts from the PIT. */
@@ -132,7 +148,8 @@ void local_apic_config_timer(void)
 
 	uint32_t total_ticks = 0xFFFFFFFF - lapic.read(local_apic::TIMER_CURCOUNT);
 
-	total_ticks /= 100;
+	/* convert to LAPIC ticks per kernel clock tick */
+	total_ticks /= 10;
 
 	lapic.write(local_apic::LVT_TIMER, IRQ0 | APIC_LVT_TIMER_MODE_PERIODIC);
 	lapic.write(local_apic::TIMER_DIV, 0x3);
@@ -189,8 +206,6 @@ static void init_all_ioapic(struct acpi_madt *madt)
 
 kern_status_t apic_init(void)
 {
-	static unsigned int bsp_id = (unsigned int)-1;
-
 	/* the bootstrap processor will be the first one ro call apic_init().
 	   it is responsible for initialising the I/O APICs */
 	if (bsp_id == (unsigned int)-1) {
@@ -214,8 +229,13 @@ kern_status_t apic_init(void)
 	apic_enabled = 1;
 	irq_enable();
 
-	pit_start(1000);
+	pit_start(HZ);
+	return KERN_OK;
+
 	local_apic_config_timer();
+	pit_stop();
+
+	hook_irq(IRQ0, &lapic_clock_irq_hook);
 
 	return KERN_OK;
 }

arch/x86_64/init.c

@@ -1,4 +1,5 @@
 #include <socks/pmap.h>
+#include <socks/clock.h>
 #include <socks/types.h>
 #include <socks/object.h>
 #include <arch/e820.h>
@@ -46,6 +47,7 @@ int ml_init(uintptr_t arg)
 
 	bootstrap_cpu_init();
 	vgacon_init();
+	clock_calibrate(500);
 
 	print_kernel_banner();
 

arch/x86_64/pit.c

@@ -1,13 +1,42 @@
 #include <socks/printk.h>
+#include <socks/clock.h>
 #include <socks/cpu.h>
 #include <arch/ports.h>
 #include <arch/irq.h>
 
-static unsigned long long tick_counter = 0;
+#define PIT_COUNTER0                    0x40
+#define PIT_CMD                         0x43
+
+#define CMD_BINARY                      0x00    // Use Binary counter values
+#define CMD_BCD                         0x01    // Use Binary Coded Decimal counter values
+
+#define CMD_MODE0                       0x00    // Interrupt on Terminal Count
+#define CMD_MODE1                       0x02    // Hardware Retriggerable One-Shot
+#define CMD_MODE2                       0x04    // Rate Generator
+#define CMD_MODE3                       0x06    // Square Wave
+#define CMD_MODE4                       0x08    // Software Trigerred Strobe
+#define CMD_MODE5                       0x0a    // Hardware Trigerred Strobe
+
+#define CMD_LATCH                       0x00
+#define CMD_RW_LOW                      0x10    // Least Significant Byte
+#define CMD_RW_HI                       0x20    // Most Significant Byte
+#define CMD_RW_BOTH                     0x30    // Least followed by Most Significant Byte
+
+#define CMD_COUNTER0                    0x00
+#define CMD_COUNTER1                    0x40
+#define CMD_COUNTER2                    0x80
+#define CMD_READBACK                    0xc0
+
+#define PIT_FREQUENCY                   1193182
+
+
+static volatile unsigned long long ticks = 0;
 
 static int pit_callback(void)
 {
-	tick_counter++;
+	clock_advance(1);
+	ticks++;
+
 	return 0;
 }
 
@@ -17,39 +46,20 @@ static struct irq_hook pit_irq_hook = {
 
 void pit_start(unsigned int hz)
 {
-	tick_counter = 0;
-
-	unsigned int divisor = 1193180 / hz;
-
-	outportb(0x43, 0x36);
-	uint8_t lo = (uint8_t)(divisor & 0xFF);
-	uint8_t hi = (uint8_t)((divisor >> 8) & 0xFF);
-
-	outportb(0x40, lo);
-	outportb(0x40, hi);
-
 	hook_irq(IRQ0, &pit_irq_hook);
+
+	unsigned int divisor = PIT_FREQUENCY / hz;
+	outportb(PIT_CMD, CMD_BINARY | CMD_MODE2 | CMD_RW_BOTH | CMD_COUNTER0);
+	outportb(PIT_COUNTER0, divisor);
+	outportb(PIT_COUNTER0, divisor >> 8);
 }
 
 void pit_stop(void)
 {
-	/* lowest possible frequency */
+	unsigned int divisor = PIT_FREQUENCY / 20;
-	unsigned int divisor = 1193180;
+	outportb(PIT_CMD, CMD_BINARY | CMD_MODE4 | CMD_RW_BOTH | CMD_COUNTER0);
-
+	outportb(PIT_COUNTER0, divisor);
-	outportb(0x43, 0x36);
+	outportb(PIT_COUNTER0, divisor >> 8);
-	uint8_t lo = (uint8_t)(divisor & 0xFF);
-	uint8_t hi = (uint8_t)((divisor >> 8) & 0xFF);
-
-	outportb(0x40, lo);
-	outportb(0x40, hi);
 
 	unhook_irq(IRQ0, &pit_irq_hook);
 }
-
-void pit_wait(unsigned int ticks)
-{
-	unsigned long long end = tick_counter + ticks;
-
-	while (READ_ONCE(tick_counter) < end) {
-	}
-}

include/socks/clock.h

@@ -0,0 +1,27 @@
+#ifndef SOCKS_CLOCK_H_
+#define SOCKS_CLOCK_H_
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+#define HZ (clock_hz())
+
+typedef uint64_t clock_ticks_t;
+
+extern volatile clock_ticks_t clock_ticks;
+
+extern clock_ticks_t clock_hz(void);
+
+extern void clock_calibrate(clock_ticks_t hz);
+extern void clock_advance(clock_ticks_t ticks);
+extern void clock_wait(clock_ticks_t ticks);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

kernel/clock.c

@@ -0,0 +1,29 @@
+#include <socks/clock.h>
+#include <socks/printk.h>
+#include <socks/compiler.h>
+
+static clock_ticks_t ticks_per_sec = 0;
+volatile clock_ticks_t clock_ticks = 0;
+
+clock_ticks_t clock_hz(void)
+{
+	return ticks_per_sec;
+}
+
+void clock_calibrate(clock_ticks_t hz)
+{
+	ticks_per_sec = hz;
+}
+
+void clock_advance(clock_ticks_t ticks)
+{
+	clock_ticks += ticks;
+}
+
+void clock_wait(clock_ticks_t ticks)
+{
+	clock_ticks_t end = clock_ticks + ticks;
+	while (clock_ticks < end) {
+
+	}
+}