+/**
+ * @file rtc.c
+ * @author Lunaixsky
+ * @brief RTC & CMOS abstraction. Reference: MC146818A & Intel Series 500 PCH
+ * datasheet
+ * @version 0.1
+ * @date 2022-03-07
+ *
+ * @copyright Copyright (c) 2022
+ *
+ */
+
+#include <lunaix/isrm.h>
+
+#include <hal/rtc/mc146818a.h>
+
+#include <klibc/string.h>
+
+#include <sys/interrupts.h>
+#include <sys/port_io.h>
+
+#define RTC_INDEX_PORT 0x70
+#define RTC_TARGET_PORT 0x71
+
+#define WITH_NMI_DISABLED 0x80
+
+#define RTC_CURRENT_CENTRY 20
+
+#define RTC_REG_YRS 0x9
+#define RTC_REG_MTH 0x8
+#define RTC_REG_DAY 0x7
+#define RTC_REG_WDY 0x6
+#define RTC_REG_HRS 0x4
+#define RTC_REG_MIN 0x2
+#define RTC_REG_SEC 0x0
+
+#define RTC_REG_A 0xA
+#define RTC_REG_B 0xB
+#define RTC_REG_C 0xC
+#define RTC_REG_D 0xD
+
+#define RTC_BIN_ENCODED(reg) (reg & 0x04)
+#define RTC_24HRS_ENCODED(reg) (reg & 0x02)
+
+#define RTC_TIMER_BASE_FREQUENCY 1024
+#define RTC_TIMER_ON 0x40
+
+#define RTC_FREQUENCY_1024HZ 0b110
+#define RTC_DIVIDER_33KHZ (0b010 << 4)
+
+struct mc146818
+{
+ struct hwrtc* rtc_context;
+ u32_t rtc_iv;
+ int ticking;
+ void (*on_tick_cb)(const struct hwrtc*);
+};
+
+#define rtc_state(data) ((struct mc146818*)(data))
+
+static u8_t
+rtc_read_reg(u8_t reg_selector)
+{
+ port_wrbyte(RTC_INDEX_PORT, reg_selector);
+ return port_rdbyte(RTC_TARGET_PORT);
+}
+
+static void
+rtc_write_reg(u8_t reg_selector, u8_t val)
+{
+ port_wrbyte(RTC_INDEX_PORT, reg_selector);
+ port_wrbyte(RTC_TARGET_PORT, val);
+}
+
+static u8_t
+bcd2dec(u8_t bcd)
+{
+ return ((bcd & 0xF0) >> 1) + ((bcd & 0xF0) >> 3) + (bcd & 0xf);
+}
+
+static void
+rtc_enable_timer()
+{
+ u8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
+ rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB | RTC_TIMER_ON);
+}
+
+static void
+rtc_disable_timer()
+{
+ u8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
+ rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB & ~RTC_TIMER_ON);
+}
+
+static void
+clock_walltime(struct hwrtc* rtc, datetime_t* datetime)
+{
+ datetime_t current;
+
+ do {
+ while (rtc_read_reg(RTC_REG_A) & 0x80)
+ ;
+ memcpy(¤t, datetime, sizeof(datetime_t));
+
+ datetime->year = rtc_read_reg(RTC_REG_YRS);
+ datetime->month = rtc_read_reg(RTC_REG_MTH);
+ datetime->day = rtc_read_reg(RTC_REG_DAY);
+ datetime->weekday = rtc_read_reg(RTC_REG_WDY);
+ datetime->hour = rtc_read_reg(RTC_REG_HRS);
+ datetime->minute = rtc_read_reg(RTC_REG_MIN);
+ datetime->second = rtc_read_reg(RTC_REG_SEC);
+ } while (!datatime_eq(datetime, ¤t));
+
+ u8_t regbv = rtc_read_reg(RTC_REG_B);
+
+ // Convert from bcd to binary when needed
+ if (!RTC_BIN_ENCODED(regbv)) {
+ datetime->year = bcd2dec(datetime->year);
+ datetime->month = bcd2dec(datetime->month);
+ datetime->day = bcd2dec(datetime->day);
+ datetime->hour = bcd2dec(datetime->hour);
+ datetime->minute = bcd2dec(datetime->minute);
+ datetime->second = bcd2dec(datetime->second);
+ }
+
+ // To 24 hour format
+ if (!RTC_24HRS_ENCODED(regbv) && (datetime->hour >> 7)) {
+ datetime->hour = 12 + (datetime->hour & 0x80);
+ }
+
+ datetime->year += RTC_CURRENT_CENTRY * 100;
+}
+
+static int
+mc146818_check_support(struct hwrtc* rtc)
+{
+#if __ARCH__ == i386
+ return 1;
+#else
+ return 0;
+#endif
+}
+
+static void
+rtc_init(struct hwrtc* rtc)
+{
+ u8_t regA = rtc_read_reg(RTC_REG_A | WITH_NMI_DISABLED);
+ regA = (regA & ~0x7f) | RTC_FREQUENCY_1024HZ | RTC_DIVIDER_33KHZ;
+ rtc_write_reg(RTC_REG_A | WITH_NMI_DISABLED, regA);
+
+ rtc_state(rtc->data)->rtc_context = rtc;
+
+ // Make sure the rtc timer is disabled by default
+ rtc_disable_timer();
+}
+
+static struct mc146818 rtc_state = { .ticking = 0 };
+
+static void
+__rtc_tick(const isr_param* param)
+{
+ rtc_state.on_tick_cb(rtc_state.rtc_context);
+
+ (void)rtc_read_reg(RTC_REG_C);
+}
+
+static void
+rtc_do_ticking(struct hwrtc* rtc, void (*on_tick)())
+{
+ if (!on_tick || rtc_state(rtc->data)->ticking) {
+ return;
+ }
+
+ struct mc146818* state = rtc_state(rtc->data);
+ state->ticking = 1;
+ state->on_tick_cb = on_tick;
+
+ /* We realise that using rtc to tick something has an extremely rare use
+ * case (e.g., calibrating some timer). Therefore, we will release this
+ * allocated IV when rtc ticking is no longer required to save IV
+ * resources.
+ */
+ state->rtc_iv = isrm_bindirq(PC_AT_IRQ_RTC, __rtc_tick);
+
+ rtc_enable_timer();
+}
+
+static void
+rtc_end_ticking(struct hwrtc* rtc)
+{
+ if (!rtc_state(rtc->data)->ticking) {
+ return;
+ }
+
+ rtc_disable_timer();
+
+ // do some delay, ensure there is no more interrupt from rtc before we
+ // release isr
+ port_delay(1000);
+
+ isrm_ivfree(rtc_state(rtc->data)->rtc_iv);
+
+ rtc_state(rtc->data)->ticking = 0;
+}
+
+static struct hwrtc hwrtc_mc146818a = { .name = "mc146818a",
+ .data = &rtc_state,
+ .init = rtc_init,
+ .base_freq = RTC_TIMER_BASE_FREQUENCY,
+ .supported = mc146818_check_support,
+ .get_walltime = clock_walltime,
+ .do_ticking = rtc_do_ticking,
+ .end_ticking = rtc_end_ticking };
+
+struct hwrtc*
+mc146818a_rtc_context()
+{
+ return &hwrtc_mc146818a;
+}
git://scm.lunaixsky.com / lunaix-os.git / commitdiff