/* * Dallas Semiconductors 1603 RTC driver * * Brian Murphy <brian@murphy.dk> * */ #include <linux/kernel.h> #include <asm/lasat/lasat.h> #include <linux/delay.h> #include <asm/lasat/ds1603.h> #include "ds1603.h" #define READ_TIME_CMD 0x81 #define SET_TIME_CMD 0x80 #define TRIMMER_SET_CMD 0xC0 #define TRIMMER_VALUE_MASK 0x38 #define TRIMMER_SHIFT 3 struct ds_defs *ds1603 = NULL; /* HW specific register functions */ static void rtc_reg_write(unsigned long val) { *ds1603->reg = val; } static unsigned long rtc_reg_read(void) { unsigned long tmp = *ds1603->reg; return tmp; } static unsigned long rtc_datareg_read(void) { unsigned long tmp = *ds1603->data_reg; return tmp; } static void rtc_nrst_high(void) { rtc_reg_write(rtc_reg_read() | ds1603->rst); } static void rtc_nrst_low(void) { rtc_reg_write(rtc_reg_read() & ~ds1603->rst); } static void rtc_cycle_clock(unsigned long data) { data |= ds1603->clk; rtc_reg_write(data); lasat_ndelay(250); if (ds1603->data_reversed) data &= ~ds1603->data; else data |= ds1603->data; data &= ~ds1603->clk; rtc_reg_write(data); lasat_ndelay(250 + ds1603->huge_delay); } static void rtc_write_databit(unsigned int bit) { unsigned long data = rtc_reg_read(); if (ds1603->data_reversed) bit = !bit; if (bit) data |= ds1603->data; else data &= ~ds1603->data; rtc_reg_write(data); lasat_ndelay(50 + ds1603->huge_delay); rtc_cycle_clock(data); } static unsigned int rtc_read_databit(void) { unsigned int data; data = (rtc_datareg_read() & (1 << ds1603->data_read_shift)) >> ds1603->data_read_shift; rtc_cycle_clock(rtc_reg_read()); return data; } static void rtc_write_byte(unsigned int byte) { int i; for (i = 0; i<=7; i++) { rtc_write_databit(byte & 1L); byte >>= 1; } } static void rtc_write_word(unsigned long word) { int i; for (i = 0; i<=31; i++) { rtc_write_databit(word & 1L); word >>= 1; } } static unsigned long rtc_read_word(void) { int i; unsigned long word = 0; unsigned long shift = 0; for (i = 0; i<=31; i++) { word |= rtc_read_databit() << shift; shift++; } return word; } static void rtc_init_op(void) { rtc_nrst_high(); rtc_reg_write(rtc_reg_read() & ~ds1603->clk); lasat_ndelay(50); } static void rtc_end_op(void) { rtc_nrst_low(); lasat_ndelay(1000); } /* interface */ unsigned long ds1603_read(void) { unsigned long word; rtc_init_op(); rtc_write_byte(READ_TIME_CMD); word = rtc_read_word(); rtc_end_op(); return word; } int ds1603_set(unsigned long time) { rtc_init_op(); rtc_write_byte(SET_TIME_CMD); rtc_write_word(time); rtc_end_op(); return 0; } void ds1603_set_trimmer(unsigned int trimval) { rtc_init_op(); rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK) | (TRIMMER_SET_CMD)); rtc_end_op(); } void ds1603_disable(void) { ds1603_set_trimmer(TRIMMER_DISABLE_RTC); } void ds1603_enable(void) { ds1603_set_trimmer(TRIMMER_DEFAULT); }