From 21bcfa6b707403a43ea8ac4a285114951cf29059 Mon Sep 17 00:00:00 2001
From: Ada Christine <adachristine18@gmail.com>
Date: Fri, 18 Feb 2022 17:24:17 +0000
Subject: timer callback interface

---
 kc/core/pit8253.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 kc/core/pit8253.h |  3 +++
 kc/core/timer.h   | 11 +++++++++++
 3 files changed, 69 insertions(+), 3 deletions(-)

(limited to 'kc')

diff --git a/kc/core/pit8253.c b/kc/core/pit8253.c
index 6f6256a..5653eb9 100644
--- a/kc/core/pit8253.c
+++ b/kc/core/pit8253.c
@@ -2,6 +2,7 @@
 #include "pic8259.h"
 #include "port.h"
 #include "kprint.h"
+#include "memory.h"
 
 #include <stdatomic.h>
 
@@ -19,10 +20,11 @@
 #define PIT_HZ 1193182U
 #define PIT_HZ_MIN (PIT_HZ/0xffff)
 
-static void pit8253_set_divisor(uint16_t divisor);
+static void set_divisor(uint16_t divisor);
 
 static volatile atomic_uint_fast64_t count = 0;
 static uint16_t divisor = 0;
+static struct timer_callback_list *callback_list;
 
 const struct timer_source pit8253_timer_source =
 {
@@ -34,6 +36,9 @@ const struct timer_source pit8253_timer_source =
     pit8253_set_frequency,
     pit8253_get_frequency,
 
+    pit8253_append_callback,
+    pit8253_delete_callback,
+
     pit8253_nanoseconds_elapsed,
     pit8253_nanoseconds_delta
 };
@@ -43,6 +48,15 @@ int pit8253_callback(uint8_t irq)
     (void)irq;
     count++;
 
+    struct timer_callback_list *l = callback_list;
+    uint64_t time_now = pit8253_nanoseconds_elapsed();
+
+    while (l)
+    {
+        l->func(time_now);
+        l = l->next;
+    }
+
     return 0;
 }
 
@@ -72,7 +86,7 @@ void pit8253_set_frequency(uint32_t frequency)
         kprintf("warning: set timer to minimum frequency\n");
     }
 
-    pit8253_set_divisor(d);
+    set_divisor(d);
 }
 
 uint32_t pit8253_get_frequency(void)
@@ -80,6 +94,44 @@ uint32_t pit8253_get_frequency(void)
     return PIT_HZ/divisor;
 }
 
+static struct timer_callback_list *find_callback(timer_callback func)
+{
+    struct timer_callback_list *l = callback_list;
+
+    while (l)
+    {
+        if (l->func == func)
+        {
+            return l;
+        }
+
+        l = l->next;
+    }
+
+    return NULL;
+}
+
+int pit8253_append_callback(timer_callback func)
+{
+    if (!find_callback(func))
+    {
+        struct timer_callback_list *item = heap_alloc(sizeof(*item));
+        item->func = func;
+        item->next = callback_list;
+        callback_list = item;
+
+        return 0;
+    }
+
+    return -1;
+}
+
+void pit8253_delete_callback(timer_callback func)
+{
+    // TODO: implement this
+    (void)func;
+}
+
 uint64_t pit8253_nanoseconds_elapsed(void)
 {
     return pit8253_nanoseconds_delta() * atomic_load(&count);
@@ -90,7 +142,7 @@ uint64_t pit8253_nanoseconds_delta(void)
     return (TIMER_NANOSECOND * divisor)/PIT_HZ;
 }
 
-static void pit8253_set_divisor(uint16_t d)
+static void set_divisor(uint16_t d)
 {
     outb(PIT8253_CMD, CONFIG_CHANNEL_0);
     outb(PIT8253_DATA0, (uint8_t)d);
diff --git a/kc/core/pit8253.h b/kc/core/pit8253.h
index 32cb9b1..b6f3d10 100644
--- a/kc/core/pit8253.h
+++ b/kc/core/pit8253.h
@@ -10,6 +10,9 @@ void pit8253_stop(void);
 void pit8253_set_frequency(uint32_t frequency);
 uint32_t pit8253_get_frequency(void);
 
+int pit8253_append_callback(timer_callback func);
+void pit8253_delete_callback(timer_callback func);
+
 uint64_t pit8253_nanoseconds_elapsed(void);
 uint64_t pit8253_nanoseconds_delta(void);
 
diff --git a/kc/core/timer.h b/kc/core/timer.h
index 6960a4b..b41aa35 100644
--- a/kc/core/timer.h
+++ b/kc/core/timer.h
@@ -5,6 +5,14 @@
 #define TIMER_MICROSECOND 1000000ULL
 #define TIMER_NANOSECOND 1000000000ULL
 
+typedef int (*timer_callback)(uint64_t nanoseconds);
+
+struct timer_callback_list
+{
+    timer_callback func;
+    struct timer_callback_list *next;
+};
+
 struct timer_source
 {
     const char *name;
@@ -15,6 +23,9 @@ struct timer_source
     void (*set_frequency)(uint32_t frequency);
     uint32_t (*get_frequency)(void);
 
+    int (*append_callback)(timer_callback func);
+    void (*delete_callback)(timer_callback func);
+
     uint64_t (*nanoseconds_elapsed)(void);
     uint64_t (*nanoseconds_delta)(void);
 };
-- 
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