From: Tulio A M Mendes <tadryanom@hotmail.com>
Date: Thu, 12 Feb 2026 03:20:48 +0000 (-0300)
Subject: feat: RTC driver (CMOS real-time clock) + clock_gettime(CLOCK_REALTIME) uses wall... 
X-Git-Url: https://projects.tadryanom.me/sitemap.xml?a=commitdiff_plain;h=54b5da1aa8644a46b56054b1fbe8d6648d53ffda;p=AdrOS.git

feat: RTC driver (CMOS real-time clock) + clock_gettime(CLOCK_REALTIME) uses wall-clock time
---

diff --git a/include/rtc.h b/include/rtc.h
new file mode 100644
index 0000000..8b35bc0
--- /dev/null
+++ b/include/rtc.h
@@ -0,0 +1,19 @@
+#ifndef RTC_H
+#define RTC_H
+
+#include <stdint.h>
+
+struct rtc_time {
+    uint8_t second;
+    uint8_t minute;
+    uint8_t hour;
+    uint8_t day;
+    uint8_t month;
+    uint16_t year;
+};
+
+void rtc_init(void);
+void rtc_read(struct rtc_time* t);
+uint32_t rtc_unix_timestamp(void);
+
+#endif
diff --git a/src/drivers/rtc.c b/src/drivers/rtc.c
new file mode 100644
index 0000000..4a71ab5
--- /dev/null
+++ b/src/drivers/rtc.c
@@ -0,0 +1,95 @@
+#include "rtc.h"
+
+#define CMOS_ADDR 0x70
+#define CMOS_DATA 0x71
+
+#define RTC_REG_SEC   0x00
+#define RTC_REG_MIN   0x02
+#define RTC_REG_HOUR  0x04
+#define RTC_REG_DAY   0x07
+#define RTC_REG_MON   0x08
+#define RTC_REG_YEAR  0x09
+#define RTC_REG_STATB 0x0B
+
+static inline void port_outb(uint16_t port, uint8_t val) {
+    __asm__ volatile("outb %0, %1" : : "a"(val), "Nd"(port));
+}
+
+static inline uint8_t port_inb(uint16_t port) {
+    uint8_t ret;
+    __asm__ volatile("inb %1, %0" : "=a"(ret) : "Nd"(port));
+    return ret;
+}
+
+static uint8_t cmos_read(uint8_t reg) {
+    port_outb(CMOS_ADDR, reg);
+    return port_inb(CMOS_DATA);
+}
+
+static int rtc_updating(void) {
+    port_outb(CMOS_ADDR, 0x0A);
+    return port_inb(CMOS_DATA) & 0x80;
+}
+
+static uint8_t bcd_to_bin(uint8_t v) {
+    return (uint8_t)((v & 0x0F) + ((v >> 4) * 10));
+}
+
+void rtc_init(void) {
+    /* Nothing to do — CMOS is always available on x86 */
+}
+
+void rtc_read(struct rtc_time* t) {
+    while (rtc_updating()) {}
+
+    t->second = cmos_read(RTC_REG_SEC);
+    t->minute = cmos_read(RTC_REG_MIN);
+    t->hour   = cmos_read(RTC_REG_HOUR);
+    t->day    = cmos_read(RTC_REG_DAY);
+    t->month  = cmos_read(RTC_REG_MON);
+    t->year   = cmos_read(RTC_REG_YEAR);
+
+    uint8_t statb = cmos_read(RTC_REG_STATB);
+    int bcd = !(statb & 0x04);
+
+    if (bcd) {
+        t->second = bcd_to_bin(t->second);
+        t->minute = bcd_to_bin(t->minute);
+        t->hour   = bcd_to_bin((uint8_t)(t->hour & 0x7F));
+        t->day    = bcd_to_bin(t->day);
+        t->month  = bcd_to_bin(t->month);
+        t->year   = bcd_to_bin((uint8_t)t->year);
+    }
+
+    t->year += 2000;
+
+    if (!(statb & 0x02) && (cmos_read(RTC_REG_HOUR) & 0x80)) {
+        t->hour = (uint8_t)((t->hour + 12) % 24);
+    }
+}
+
+static int is_leap(uint16_t y) {
+    return (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0);
+}
+
+uint32_t rtc_unix_timestamp(void) {
+    struct rtc_time t;
+    rtc_read(&t);
+
+    static const uint16_t mdays[12] = {
+        0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
+    };
+
+    uint32_t y = t.year;
+    uint32_t days = 0;
+
+    for (uint32_t i = 1970; i < y; i++) {
+        days += is_leap((uint16_t)i) ? 366 : 365;
+    }
+
+    days += mdays[t.month - 1];
+    if (t.month > 2 && is_leap((uint16_t)y)) days++;
+    days += t.day - 1;
+
+    return days * 86400 + t.hour * 3600 + t.minute * 60 + t.second;
+}
diff --git a/src/kernel/syscall.c b/src/kernel/syscall.c
index b133e82..0bb88fe 100644
--- a/src/kernel/syscall.c
+++ b/src/kernel/syscall.c
@@ -1488,13 +1488,18 @@ static int syscall_clock_gettime_impl(uint32_t clk_id, struct timespec* user_tp)
 
     if (clk_id != CLOCK_REALTIME && clk_id != CLOCK_MONOTONIC) return -EINVAL;
 
-    uint32_t ticks = get_tick_count();
-    const uint32_t TICK_MS = 20;
-    uint32_t total_ms = ticks * TICK_MS;
-
     struct timespec tp;
-    tp.tv_sec = total_ms / 1000U;
-    tp.tv_nsec = (total_ms % 1000U) * 1000000U;
+    if (clk_id == CLOCK_REALTIME) {
+        extern uint32_t rtc_unix_timestamp(void);
+        tp.tv_sec = rtc_unix_timestamp();
+        tp.tv_nsec = 0;
+    } else {
+        uint32_t ticks = get_tick_count();
+        const uint32_t TICK_MS = 20;
+        uint32_t total_ms = ticks * TICK_MS;
+        tp.tv_sec = total_ms / 1000U;
+        tp.tv_nsec = (total_ms % 1000U) * 1000000U;
+    }
 
     if (copy_to_user(user_tp, &tp, sizeof(tp)) < 0) return -EFAULT;
     return 0;