Timer for raspberry pi.

arch/raspberrypi/build.mk

@@ -1,3 +1,4 @@
 
 OBJS += arch/raspberrypi/irq.o
 OBJS += arch/raspberrypi/uart.o
+OBJS += arch/raspberrypi/timer.o

arch/raspberrypi/include/hardware.h

@@ -12,5 +12,6 @@
 #define MMIO_BASE_PHYSICAL 0x20000000
 #define TOTAL_MEMORY_SIZE   0x1ff00000  /* 511MB */
 #define UART_IRQ 29
+#define TIMER_IRQ 1
 
 #endif

arch/raspberrypi/irq.c

@@ -1,6 +1,7 @@
 #include <irq.h>
 #include <vm.h>
 #include <lib/string.h>
+#include <klib.h>
 
 /* memory mapping for the interrupt controller */
 #define PIC MMIO_P2V(0x2000B000)

arch/raspberrypi/timer.c

@@ -0,0 +1,45 @@
+#include <timer.h>
+#include <types.h>
+#include <vm.h>
+#include <klib.h>
+
+/* http://www.valvers.com/open-software/raspberry-pi/step04-bare-metal-programming-in-c-pt4/ */
+
+/* memory mapping for timer */
+#define TIMER MMIO_P2V(0x20003000)
+
+#define CS 0x20003000
+#define CLO 0x20003004
+#define C0 0x2000300C
+#define C1 0x20003010
+#define C2 0x20003014
+#define C3 0x20003018
+
+
+static void PUT32(uint32_t address, uint32_t value) {
+	*MMIO_P2V(address) = value;
+}
+
+static uint32_t GET32(uint32_t address) {
+	return *MMIO_P2V(address);
+}
+
+static uint32_t saved_interval_microsecond;
+
+
+void timer_set_interval(uint32_t interval_microsecond)
+{
+	saved_interval_microsecond = interval_microsecond;
+	timer_clear_interrupt();
+}
+
+void timer_clear_interrupt(void)
+{
+	unsigned int ra;
+
+	PUT32(CS, 2);
+
+	ra = GET32(CLO);	
+	ra += saved_interval_microsecond;
+	PUT32(C1, ra);
+}

kernel/irq.c

@@ -1,4 +1,5 @@
 #include <irq.h>
+#include <klib.h>
 
 
 /* interrupt handler vector */

kernel/proc/scheduler.c

@@ -17,8 +17,8 @@ void handle_timer(void)
 void scheduler_init(void)
 {
 	round_robin_index = 0;
-	timer_set_interval(1000);
-	register_interrupt_handler(0x5, handle_timer);
+	timer_set_interval(100000);
+	register_interrupt_handler(TIMER_IRQ, handle_timer);
 }
 
 void schedule(void)

user/concurrency_test.c

@@ -6,9 +6,9 @@ void _start()
 	int i = 0;
 	fork();
 
-	for (i = 0; i < 5; i++) {
+	for (i = 0; i < 50000; i++) {
 		printf("step %d at pid %d\n", i, getpid());
-		yield();
+		//yield();
 	}
 
 	exit(0);