lunaix-os/hal/rtc/mc146818a.c

   1 /**
   2  * @file rtc.c
   3  * @author Lunaixsky
   4  * @brief RTC & CMOS abstraction. Reference: MC146818A & Intel Series 500 PCH
   5  * datasheet
   6  * @version 0.1
   7  * @date 2022-03-07
   8  *
   9  * @copyright Copyright (c) 2022
  10  *
  11  */
  12
  13 #include <lunaix/isrm.h>
  14
  15 #include <hal/rtc/mc146818a.h>
  16
  17 #include <klibc/string.h>
  18
  19 #include <sys/interrupts.h>
  20 #include <sys/port_io.h>
  21
  22 #define RTC_INDEX_PORT 0x70
  23 #define RTC_TARGET_PORT 0x71
  24
  25 #define WITH_NMI_DISABLED 0x80
  26
  27 #define RTC_CURRENT_CENTRY 20
  28
  29 #define RTC_REG_YRS 0x9
  30 #define RTC_REG_MTH 0x8
  31 #define RTC_REG_DAY 0x7
  32 #define RTC_REG_WDY 0x6
  33 #define RTC_REG_HRS 0x4
  34 #define RTC_REG_MIN 0x2
  35 #define RTC_REG_SEC 0x0
  36
  37 #define RTC_REG_A 0xA
  38 #define RTC_REG_B 0xB
  39 #define RTC_REG_C 0xC
  40 #define RTC_REG_D 0xD
  41
  42 #define RTC_BIN_ENCODED(reg) (reg & 0x04)
  43 #define RTC_24HRS_ENCODED(reg) (reg & 0x02)
  44
  45 #define RTC_TIMER_BASE_FREQUENCY 1024
  46 #define RTC_TIMER_ON 0x40
  47
  48 #define RTC_FREQUENCY_1024HZ 0b110
  49 #define RTC_DIVIDER_33KHZ (0b010 << 4)
  50
  51 struct mc146818
  52 {
  53     struct hwrtc* rtc_context;
  54     u32_t rtc_iv;
  55     int ticking;
  56     void (*on_tick_cb)(const struct hwrtc*);
  57 };
  58
  59 #define rtc_state(data) ((struct mc146818*)(data))
  60
  61 static u8_t
  62 rtc_read_reg(u8_t reg_selector)
  63 {
  64     port_wrbyte(RTC_INDEX_PORT, reg_selector);
  65     return port_rdbyte(RTC_TARGET_PORT);
  66 }
  67
  68 static void
  69 rtc_write_reg(u8_t reg_selector, u8_t val)
  70 {
  71     port_wrbyte(RTC_INDEX_PORT, reg_selector);
  72     port_wrbyte(RTC_TARGET_PORT, val);
  73 }
  74
  75 static u8_t
  76 bcd2dec(u8_t bcd)
  77 {
  78     return ((bcd & 0xF0) >> 1) + ((bcd & 0xF0) >> 3) + (bcd & 0xf);
  79 }
  80
  81 static void
  82 rtc_enable_timer()
  83 {
  84     u8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
  85     rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB | RTC_TIMER_ON);
  86 }
  87
  88 static void
  89 rtc_disable_timer()
  90 {
  91     u8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
  92     rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB & ~RTC_TIMER_ON);
  93 }
  94
  95 static void
  96 clock_walltime(struct hwrtc* rtc, datetime_t* datetime)
  97 {
  98     datetime_t current;
  99
 100     do {
 101         while (rtc_read_reg(RTC_REG_A) & 0x80)
 102             ;
 103         memcpy(&current, datetime, sizeof(datetime_t));
 104
 105         datetime->year = rtc_read_reg(RTC_REG_YRS);
 106         datetime->month = rtc_read_reg(RTC_REG_MTH);
 107         datetime->day = rtc_read_reg(RTC_REG_DAY);
 108         datetime->weekday = rtc_read_reg(RTC_REG_WDY);
 109         datetime->hour = rtc_read_reg(RTC_REG_HRS);
 110         datetime->minute = rtc_read_reg(RTC_REG_MIN);
 111         datetime->second = rtc_read_reg(RTC_REG_SEC);
 112     } while (!datatime_eq(datetime, &current));
 113
 114     u8_t regbv = rtc_read_reg(RTC_REG_B);
 115
 116     // Convert from bcd to binary when needed
 117     if (!RTC_BIN_ENCODED(regbv)) {
 118         datetime->year = bcd2dec(datetime->year);
 119         datetime->month = bcd2dec(datetime->month);
 120         datetime->day = bcd2dec(datetime->day);
 121         datetime->hour = bcd2dec(datetime->hour);
 122         datetime->minute = bcd2dec(datetime->minute);
 123         datetime->second = bcd2dec(datetime->second);
 124     }
 125
 126     // To 24 hour format
 127     if (!RTC_24HRS_ENCODED(regbv) && (datetime->hour >> 7)) {
 128         datetime->hour = 12 + (datetime->hour & 0x80);
 129     }
 130
 131     datetime->year += RTC_CURRENT_CENTRY * 100;
 132 }
 133
 134 static int
 135 mc146818_check_support(struct hwrtc* rtc)
 136 {
 137 #if __ARCH__ == i386
 138     return 1;
 139 #else
 140     return 0;
 141 #endif
 142 }
 143
 144 static void
 145 rtc_init(struct hwrtc* rtc)
 146 {
 147     u8_t regA = rtc_read_reg(RTC_REG_A | WITH_NMI_DISABLED);
 148     regA = (regA & ~0x7f) | RTC_FREQUENCY_1024HZ | RTC_DIVIDER_33KHZ;
 149     rtc_write_reg(RTC_REG_A | WITH_NMI_DISABLED, regA);
 150
 151     rtc_state(rtc->data)->rtc_context = rtc;
 152
 153     // Make sure the rtc timer is disabled by default
 154     rtc_disable_timer();
 155 }
 156
 157 static struct mc146818 rtc_state = { .ticking = 0 };
 158
 159 static void
 160 __rtc_tick(const isr_param* param)
 161 {
 162     rtc_state.on_tick_cb(rtc_state.rtc_context);
 163
 164     (void)rtc_read_reg(RTC_REG_C);
 165 }
 166
 167 static void
 168 rtc_do_ticking(struct hwrtc* rtc, void (*on_tick)())
 169 {
 170     if (!on_tick || rtc_state(rtc->data)->ticking) {
 171         return;
 172     }
 173
 174     struct mc146818* state = rtc_state(rtc->data);
 175     state->ticking = 1;
 176     state->on_tick_cb = on_tick;
 177
 178     /* We realise that using rtc to tick something has an extremely rare use
 179      * case (e.g., calibrating some timer). Therefore, we will release this
 180      * allocated IV when rtc ticking is no longer required to save IV
 181      * resources.
 182      */
 183     state->rtc_iv = isrm_bindirq(PC_AT_IRQ_RTC, __rtc_tick);
 184
 185     rtc_enable_timer();
 186 }
 187
 188 static void
 189 rtc_end_ticking(struct hwrtc* rtc)
 190 {
 191     if (!rtc_state(rtc->data)->ticking) {
 192         return;
 193     }
 194
 195     rtc_disable_timer();
 196
 197     // do some delay, ensure there is no more interrupt from rtc before we
 198     // release isr
 199     port_delay(1000);
 200
 201     isrm_ivfree(rtc_state(rtc->data)->rtc_iv);
 202
 203     rtc_state(rtc->data)->ticking = 0;
 204 }
 205
 206 static struct hwrtc hwrtc_mc146818a = { .name = "mc146818a",
 207                                         .data = &rtc_state,
 208                                         .init = rtc_init,
 209                                         .base_freq = RTC_TIMER_BASE_FREQUENCY,
 210                                         .supported = mc146818_check_support,
 211                                         .get_walltime = clock_walltime,
 212                                         .do_ticking = rtc_do_ticking,
 213                                         .end_ticking = rtc_end_ticking };
 214
 215 struct hwrtc*
 216 mc146818a_rtc_context()
 217 {
 218     return &hwrtc_mc146818a;
 219 }