Merge branch '16-realtime-clock-driver' into 'master'

Resolve "realtime clock driver"

Closes #16

See merge request bslathi19/super6502!62

sw/kernel/devices/rtc.h

@@ -6,6 +6,12 @@
 #define RTC_CMD_ADDR    0xeffe
 #define RTC_DAT_ADDR    0xefff
 
+#define RTC_THRESHOLD       0x00
+#define RTC_INCREMENT       0x10
+#define RTC_IRQ_THRESHOLD   0x20
+#define RTC_OUTPUT          0x30
+#define RTC_CONTROL         0x30
+
 /* initialize RTC with default values */
 void init_rtc(void);
 
@@ -13,4 +19,7 @@ void init_rtc(void);
 void handle_rtc(void);
 
 
+void rtc_set(uint32_t val, uint8_t idx);
+
+
 #endif

sw/kernel/devices/rtc.s

@@ -2,8 +2,11 @@
 
 .importzp tmp1
 
+.import popa
+
 .export _init_rtc
 .export _handle_rtc
+.export _rtc_set
 
 RTC_CMD = $effe
 RTC_DAT = $efff
@@ -86,7 +89,20 @@ IRQ_THRESHOLD_3     = $00
     sta RTC_DAT
     
     rts
+.endproc
 
+; void rtc_set(uint32_t val, uint8_t idx);
+.proc _rtc_set
+    sta tmp1        ; store idx in tmp1
+    ldx #$04
+L1: lda tmp1
+    sta RTC_CMD     ; store cmd+idx to CMD    
+    jsr popa        ; pop 1 byte of argument
+    sta RTC_DAT     ; write it to data
+    inc tmp1        ; increase index
+    dex         
+    bne L1          ; repeat 4 times
+    rts
 .endproc
 
 

sw/kernel/kernel.c

@@ -36,6 +36,9 @@ int main() {
 
     register_irq(&handle_rtc_interrupt, 0);
 
+    rtc_set(0xaaaa, RTC_THRESHOLD);
+    rtc_set(0xbbbb, RTC_IRQ_THRESHOLD);
+
     asm volatile("cli");
 
     // cputs("Initialize Serial\n");