driver: programmable interval timer (PIT)

Added support for the Programmable Interval Timer (PIT)

Signed-off-by: Daniele Ahmed <ahmeddan amazon   com; >

arch/x86/entry.S

@@ -95,18 +95,8 @@ ENTRY(handle_exception)
 #endif
 END_FUNC(handle_exception)
 
-ENTRY(asm_uart_handler)
-    cld
-    SAVE_REGS
-    lea com_ports, %_ASM_DI
-    call uart_handler
-    RESTORE_REGS
-#if defined(__x86_64__)
-    iretq
-#else
-    iret
-#endif
-END_FUNC(asm_uart_handler)
+interrupt_handler pit pit_interrupt_handler
+interrupt_handler uart uart_interrupt_handler
 
 ENTRY(usermode_call_asm)
     /* FIXME: Add 32-bit support */

arch/x86/traps.c

@@ -24,6 +24,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <console.h>
+#include <drivers/pit.h>
 #include <drivers/serial.h>
 #include <ktf.h>
 #include <lib.h>
@@ -38,7 +39,8 @@
 #include <mm/vmm.h>
 
 extern void ret2kern_handler(void);
-extern void asm_uart_handler(void);
+extern void asm_interrupt_handler_uart(void);
+extern void asm_interrupt_handler_pit(void);
 
 static void init_tss(percpu_t *percpu) {
 #if defined(__i386__)
@@ -145,10 +147,12 @@ void init_traps(unsigned int cpu) {
     set_intr_gate(&percpu->idt[X86_RET2KERN_INT], __KERN_CS, _ul(ret2kern_handler), GATE_DPL3, GATE_PRESENT, 0);
     /* clang-format on */
 
-    set_intr_gate(&percpu->idt[COM1_IRQ0_OFFSET], __KERN_CS, _ul(asm_uart_handler),
-                  GATE_DPL0, GATE_PRESENT, 0);
-    set_intr_gate(&percpu->idt[COM2_IRQ0_OFFSET], __KERN_CS, _ul(asm_uart_handler),
-                  GATE_DPL0, GATE_PRESENT, 0);
+    set_intr_gate(&percpu->idt[COM1_IRQ0_OFFSET], __KERN_CS,
+                  _ul(asm_interrupt_handler_uart), GATE_DPL0, GATE_PRESENT, 0);
+    set_intr_gate(&percpu->idt[COM2_IRQ0_OFFSET], __KERN_CS,
+                  _ul(asm_interrupt_handler_uart), GATE_DPL0, GATE_PRESENT, 0);
+    set_intr_gate(&percpu->idt[PIT_IRQ0_OFFSET], __KERN_CS,
+                  _ul(asm_interrupt_handler_pit), GATE_DPL0, GATE_PRESENT, 0);
 
     barrier();
     lidt(&percpu->idt_ptr);

common/kernel.c

@@ -68,5 +68,5 @@ void kernel_main(void) {
     printk("All tasks done.\n");
 
     while (1)
-        io_delay();
+        cpu_relax();
 }

common/setup.c

@@ -46,6 +46,7 @@
 #include <smp/smp.h>
 
 #include <drivers/pic.h>
+#include <drivers/pit.h>
 #include <drivers/serial.h>
 #include <slab.h>
 
@@ -222,6 +223,9 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic,
     /* Initialize console input */
     uart_input_init(0);
 
+    /* Initialize Programmable Interrupt Timer */
+    init_pit();
+
     /* Jump from .text.init section to .text */
     asm volatile("push %0; ret" ::"r"(&kernel_main));
 

drivers/pit.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2020 Amazon.com, Inc. or its affiliates.
+ * All Rights Reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 <atomic.h>
+#include <drivers/pic.h>
+#include <drivers/pit.h>
+#include <lib.h>
+#include <time.h>
+
+static volatile uint64_t ticks = 0;
+
+void init_pit(void) {
+    outb(PIT_COMMAND_PORT,
+         PIT_CHANNEL_0 & PIT_ACCESS_MODE_LH & PIT_OP_MODE_RATE & PIT_BCD_MODE);
+    outb(PIT_DATA_PORT_CH0, PIT_FREQUENCY & 0xFF);          /* send low byte */
+    outb(PIT_DATA_PORT_CH0, (PIT_FREQUENCY & 0xFF00) >> 8); /* send high byte */
+    pic_enable_irq(PIC1_DEVICE_SEL, PIT_IRQ);
+}
+
+void pit_interrupt_handler(void) { ++ticks; }
+
+void pit_sleep(uint64_t ms) {
+    uint64_t end = ticks + ms;
+    while (ticks < end) {
+        cpu_relax();
+    }
+}

drivers/serial.c

@@ -37,6 +37,8 @@ static struct {
     unsigned init;
 } input_state;
 
+extern io_port_t com_ports[2];
+
 static inline void set_port_mode(io_port_t port, bool stop_bit, uint8_t width) {
     lcr_t lcr = {0};
 
@@ -158,12 +160,12 @@ int serial_write(io_port_t port, const char *buf, size_t len) {
     return rc;
 }
 
-void uart_handler(io_port_t ports[2]) {
+void uart_interrupt_handler(void) {
     unsigned int i;
-    for (i = 0; i < sizeof(*ports); ++i) {
-        uint8_t status = inb(ports[i] + UART_IIR_REG_OFFSET);
+    for (i = 0; i < ARRAY_SIZE(com_ports); ++i) {
+        uint8_t status = inb(com_ports[i] + UART_IIR_REG_OFFSET);
         if ((status & UART_IIR_STATUS_MASK) == UART_IIR_RBR_READY) {
-            uint8_t input = inb(ports[i] + UART_RBR_REG_OFFSET);
+            uint8_t input = inb(com_ports[i] + UART_RBR_REG_OFFSET);
 
             input_state.buf[input_state.curr] = input;
             input_state.curr = (input_state.curr + 1) % sizeof(input_state.buf);

include/drivers/pic.h

@@ -49,8 +49,8 @@
 #define PIC_CASCADE_PIC2_IRQ 0x02
 #define PIC_CASCADE_PIC1_IRQ 0x04
 
-#define PIC_IRQ0_OFFSET 0x20
-#define PIC_IRQ8_OFFSET 0x28
+#define PIC_IRQ0_OFFSET 0x28
+#define PIC_IRQ8_OFFSET (PIC_IRQ0_OFFSET + 8)
 
 #define PIC_IRQ_END_OFFSET 0x08 /* One beyond the max IRQ number */
 

include/drivers/pit.h

@@ -0,0 +1,63 @@
+/*
+ * Copyright © 2020 Amazon.com, Inc. or its affiliates.
+ * All Rights Reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
+ */
+#ifndef KTF_PIT_H
+#define KTF_PIT_H
+
+#include <drivers/pic.h>
+#include <ktf.h>
+
+#define PIT_IRQ         0x00                        /* IRQ line */
+#define PIT_IRQ0_OFFSET (PIC_IRQ0_OFFSET + PIT_IRQ) /* IRQ relative to PIC master */
+
+#define PIT_OUT_FREQUENCY 1193182 /* oscillator output frequency */
+#define PIT_RELOAD        1000    /* 1ms */
+#define PIT_FREQUENCY     (PIT_OUT_FREQUENCY / PIT_RELOAD)
+#define PIT_DATA_PORT_CH0 0x40
+#define PIT_COMMAND_PORT  0x43
+
+#define PIT_CHANNEL_0        (~((1 << 7) | (1 << 6)))
+#define PIT_ACCESS_MODE_LOW  (1 << 4)
+#define PIT_ACCESS_MODE_HIGH (1 << 5)
+#define PIT_ACCESS_MODE_LH   (PIT_ACCESS_MODE_LOW | PIT_ACCESS_MODE_HIGH)
+
+enum pit_operational_mode {
+    PIT_OP_MODE_COUNT = 0x00,     /* interrupt on terminal count */
+    PIT_OP_MODE_ONE_SHOT = 0x01,  /* hardware re-triggerable one-shot */
+    PIT_OP_MODE_RATE = 0x02,      /* rate generator */
+    PIT_OP_MODE_WAVE = 0x03,      /* square wave generator */
+    PIT_OP_MODE_SW_STROBE = 0x04, /* software triggered strobe */
+    PIT_OP_MODE_HW_STROBE = 0x05, /* hardware triggered strobe */
+    PIT_OP_MODE_RATE_6 = 0x06,    /* rate generator */
+    PIT_OP_MODE_WAVE_7 = 0x07     /* square wave generator */
+};
+typedef enum pit_operational_mode pit_operational_mode_t;
+
+#define PIT_BCD_MODE (~(1 << 0))
+
+extern void init_pit(void);
+extern void pit_interrupt_handler(void);
+extern void pit_sleep(uint64_t ms);
+
+#endif

include/drivers/serial.h

@@ -125,8 +125,8 @@ typedef union interrupt_enable_register ier_t;
 /* External declarations */
 
 extern void uart_init(io_port_t port, unsigned baud);
-extern void uart_handler(io_port_t ports[2]);
 extern void uart_input_init(uint8_t dst_cpus);
+extern void uart_interrupt_handler(void);
 extern int serial_putchar(io_port_t port, char c);
 extern int serial_write(io_port_t port, const char *buf, size_t len);
 

include/time.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright © 2020 Amazon.com, Inc. or its affiliates.
+ * All Rights Reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
+ */
+#ifndef KTF_TIME_H
+#define KTF_TIME_H
+
+#include <drivers/pit.h>
+#include <ktf.h>
+
+typedef uint64_t time_t;
+
+static inline void sleep(time_t ms) { pit_sleep(ms); }
+
+#endif