ohhhhhhhhhhh (exclude linux-extra-rootfs.img build artifact)

2026-10-01 23:13:42 +08:00
parent 737a2cb0db
commit 1074962546
533 changed files with 133239 additions and 5460 deletions
@@ -0,0 +1,45 @@
+/* pit.c — PIT ch0 单发定时（LAPIC timer 校准用）
+ *
+ * 只用 mode 0（terminal count）：单发、无周期中断、不注册 IRQ handler。
+ * 禁用 mode 3 —— B7 定论：PIT mode3 方波经 IOAPIC 边沿路由会双触发 (~200Hz)。
+ */
+
+#include <utsm/pit.h>
+
+extern void outb(u16 port, u8 value);
+extern u8 inb(u16 port);
+
+#define PIT_CH0_DATA 0x40
+#define PIT_CMD      0x43
+#define PIT_BASE_HZ  1193182ULL
+
+void pit_oneshot_ms(u32 ms) {
+    u64 div = (PIT_BASE_HZ * (u64)ms) / 1000ULL;
+    if (div == 0) div = 1;
+    if (div > 65535) div = 65535;
+    /* ch0 | lo/hi | mode0 (terminal count) | binary */
+    outb(PIT_CMD, 0x30);
+    outb(PIT_CH0_DATA, (u8)(div & 0xFF));
+    outb(PIT_CH0_DATA, (u8)((div >> 8) & 0xFF));
+}
+
+u16 pit_latch_count(void) {
+    outb(PIT_CMD, 0x00);   /* ch0 latch 计数（读前锁存） */
+    u16 lo = inb(PIT_CH0_DATA);
+    u16 hi = inb(PIT_CH0_DATA);
+    return (u16)(lo | (hi << 8));
+}
+
+int pit_oneshot_expired(void) {
+    u16 c1 = pit_latch_count();
+    u16 c2 = pit_latch_count();
+    /* mode0 计到 0 后回绕继续递减：cur 回升即视为到期 */
+    return c2 >= c1;
+}
+
+void pit_quiet(void) {
+    /* ch0 mode0、计数 0：terminal count 立即到期，无后续输出/中断 */
+    outb(PIT_CMD, 0x30);
+    outb(PIT_CH0_DATA, 0x00);
+    outb(PIT_CH0_DATA, 0x00);
+}