From: acevest <zhaoyanbai@126.com>
Date: Sun, 28 May 2023 05:35:40 +0000 (+0800)
Subject: 重写8253的代码,暂时将时钟中断频率限制在20Hz
X-Git-Url: http://zhaoyanbai.com/repos/man.rndc.html?a=commitdiff_plain;h=93098e3ed4ec1790bd260bb24a78a3363403af84;p=kernel.git

重写8253的代码,暂时将时钟中断频率限制在20Hz
---

diff --git a/kernel/clock.c b/kernel/clock.c
index d5aabed..731cf60 100644
--- a/kernel/clock.c
+++ b/kernel/clock.c
@@ -10,12 +10,13 @@
  *--------------------------------------------------------------------------
  */
 
+#include <io.h>
 #include <printk.h>
 #include <sched.h>
 #include <system.h>
 #include <wait.h>
 
-volatile uint32_t jiffies = 0;  // TODO uint64
+volatile uint32_t jiffies = 0;  // TODO uint64: undefined reference to `__umoddi3'
 
 unsigned int sys_clock() { return jiffies; }
 
@@ -23,14 +24,10 @@ void debug_print_all_tasks();
 
 void dump_irq_nr_stack();
 void clk_handler(unsigned int irq, pt_regs_t *regs, void *dev_id) {
-    if (jiffies % 100 == 0) {
-        printl(MPL_CLOCK, "clock irq: %d", jiffies);
-    }
+    // if (jiffies % 100 == 0) {
+    printl(MPL_CLOCK, "clock irq: %d", jiffies);
+    // }
 
-#if 0
-    unsigned long iflags;
-    irq_save(iflags);
-#endif
     jiffies++;
 
     current->jiffies = jiffies;
@@ -40,54 +37,17 @@ void clk_handler(unsigned int irq, pt_regs_t *regs, void *dev_id) {
     // 同时其下半部分处理时间过长，直到这个时钟中断还没处理完
     // 那么这个时钟中断是完全可以打断它，且在这里把这个ticks从0减到负数
     // 而这个是uint32_t型，因此会溢出成0xFFFFFFFF
-    volatile uint32_t ticks;
-
-    ticks = current->ticks;
     if (current->ticks > 0) {
         current->ticks--;
     }
-    ticks = current->ticks;
-
-#if 0
-    if (current->ticks > TASK_MAX_PRIORITY) {
-        printl(MPL_X, "current %08x ticks %u", current, current->ticks);
-        printk("DIE: ");
-        dump_irq_nr_stack();
-    }
-#endif
 
     assert(current->ticks <= TASK_MAX_PRIORITY);  // 防止ticks被减到0后再减溢出
-
-#if 0
-    task_union *p = 0;
-    list_head_t *t = 0;
-    list_head_t *pos = 0;
-    list_for_each_safe(pos, t, &all_tasks) {
-        p = list_entry(pos, task_union, list);
-        if (0 != p->delay_jiffies && jiffies > p->delay_jiffies && p->state == TASK_WAIT) {
-            p->delay_jiffies = 0;
-            p->state = TASK_READY;
-        }
-    }
-#endif
-
-#if 0
-    debug_print_all_tasks();
-    debug_print_all_tasks();
-    debug_print_all_tasks();
-    debug_print_all_tasks();
-#endif
-
-#if 0
-    irq_restore(iflags);
-#endif
 }
 
 // 开中断执行这个函数
+// 后续放到一个内核任务中去做，需要先把禁止内核抢占做了
 const char *task_state(unsigned int state);
 void clk_bh_handler() {
-    unsigned long iflags;
-    irq_save(iflags);
     task_union *p = 0;
     list_head_t *t = 0;
     list_head_t *pos = 0;
@@ -105,5 +65,25 @@ void clk_bh_handler() {
 
     // 此处调用这个还是有问题的
     debug_print_all_tasks();
-    irq_restore(iflags);
-}
\ No newline at end of file
+}
+
+void setup_i8253(uint16_t hz) {
+    // 最低频率为18.2Hz(1193180/65536，最大计数值是65536是因为往计数器里写0就从65536开始计数)
+    assert(hz >= 19);
+
+    const uint8_t counter_no = 0;  // 第0个计数器
+    const uint8_t read_write_latch = 3;  // 0 锁存数据供CPU读；1只读写低字节；2只读写高字节；3先读写低字节，后读写高字节
+    const uint8_t mode = 2;  //
+
+    const uint8_t cmd = (counter_no << 6) | (read_write_latch << 4) || (mode << 1);  // 第0位为0表示二进制，为1表示BCD
+
+    const uint8_t i8253_cmd_port = 0x43;
+    const uint8_t i8253_data_port = 0x40 + counter_no;
+
+    const uint32_t clock_rate = 1193180;
+    uint16_t latch = (clock_rate + hz / 2) / hz;
+
+    outb_p(cmd, i8253_cmd_port);
+    outb_p(latch & 0xFF, i8253_data_port);
+    outb(latch >> 8, i8253_data_port);
+}
diff --git a/kernel/setup.c b/kernel/setup.c
index 4d2e7f5..5af3618 100644
--- a/kernel/setup.c
+++ b/kernel/setup.c
@@ -14,7 +14,6 @@
  *--------------------------------------------------------------------------
  */
 #include <bits.h>
-#include <io.h>
 #include <printk.h>
 #include <system.h>
 #include <tty.h>
@@ -23,6 +22,7 @@ extern void init_mm();
 extern void setup_gdt();
 extern void setup_idt();
 extern void setup_gate();
+void setup_i8253(uint16_t hz);
 extern void detect_cpu();
 extern void setup_sysc();
 extern void setup_pci();
@@ -37,16 +37,6 @@ extern void reboot();
 extern void cnsl_init();
 extern void init_ttys();
 
-#define HZ 100
-#define CLOCK_TICK_RATE 1193180
-#define LATCH ((CLOCK_TICK_RATE + HZ / 2) / HZ)
-
-void setup_i8253() {
-    outb_p(0x34, 0x43);
-    outb_p(LATCH & 0xFF, 0x40);
-    outb(LATCH >> 8, 0x40);
-}
-
 #define VERSION "0.3.1"
 const char *version = "Kernel version " VERSION " @ " BUILDER
                       " ["__DATE__
@@ -73,11 +63,10 @@ void setup_kernel() {
     setup_gdt();
     setup_idt();
     setup_gate();
-
-    setup_i8253();
-
     set_tss();
 
+    setup_i8253(20);
+
     setup_sysc();
 
     cnsl_init();
@@ -96,7 +85,7 @@ void setup_kernel() {
     printk(version);
 
     extern tty_t monitor_tty;
-    // tty_switch(&monitor_tty);
+    tty_switch(&monitor_tty);
 
     void ide_init();
     ide_init();