186 lines
3.2 KiB
C
186 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Dallas Semiconductors 1603 RTC driver
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*
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* Brian Murphy <brian@murphy.dk>
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*
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*/
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#include <linux/kernel.h>
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#include <asm/lasat/lasat.h>
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#include <linux/delay.h>
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#include <asm/lasat/ds1603.h>
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#include <asm/time.h>
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#include "ds1603.h"
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#define READ_TIME_CMD 0x81
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#define SET_TIME_CMD 0x80
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#define TRIMMER_SET_CMD 0xC0
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#define TRIMMER_VALUE_MASK 0x38
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#define TRIMMER_SHIFT 3
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struct ds_defs *ds1603;
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/* HW specific register functions */
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static void rtc_reg_write(unsigned long val)
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{
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*ds1603->reg = val;
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}
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static unsigned long rtc_reg_read(void)
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{
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unsigned long tmp = *ds1603->reg;
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return tmp;
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}
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static unsigned long rtc_datareg_read(void)
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{
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unsigned long tmp = *ds1603->data_reg;
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return tmp;
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}
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static void rtc_nrst_high(void)
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{
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rtc_reg_write(rtc_reg_read() | ds1603->rst);
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}
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static void rtc_nrst_low(void)
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{
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rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
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}
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static void rtc_cycle_clock(unsigned long data)
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{
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data |= ds1603->clk;
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rtc_reg_write(data);
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lasat_ndelay(250);
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if (ds1603->data_reversed)
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data &= ~ds1603->data;
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else
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data |= ds1603->data;
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data &= ~ds1603->clk;
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rtc_reg_write(data);
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lasat_ndelay(250 + ds1603->huge_delay);
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}
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static void rtc_write_databit(unsigned int bit)
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{
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unsigned long data = rtc_reg_read();
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if (ds1603->data_reversed)
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bit = !bit;
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if (bit)
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data |= ds1603->data;
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else
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data &= ~ds1603->data;
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rtc_reg_write(data);
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lasat_ndelay(50 + ds1603->huge_delay);
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rtc_cycle_clock(data);
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}
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static unsigned int rtc_read_databit(void)
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{
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unsigned int data;
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data = (rtc_datareg_read() & (1 << ds1603->data_read_shift))
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>> ds1603->data_read_shift;
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rtc_cycle_clock(rtc_reg_read());
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return data;
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}
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static void rtc_write_byte(unsigned int byte)
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{
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int i;
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for (i = 0; i <= 7; i++) {
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rtc_write_databit(byte & 1L);
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byte >>= 1;
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}
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}
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static void rtc_write_word(unsigned long word)
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{
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int i;
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for (i = 0; i <= 31; i++) {
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rtc_write_databit(word & 1L);
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word >>= 1;
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}
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}
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static unsigned long rtc_read_word(void)
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{
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int i;
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unsigned long word = 0;
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unsigned long shift = 0;
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for (i = 0; i <= 31; i++) {
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word |= rtc_read_databit() << shift;
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shift++;
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}
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return word;
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}
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static void rtc_init_op(void)
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{
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rtc_nrst_high();
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rtc_reg_write(rtc_reg_read() & ~ds1603->clk);
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lasat_ndelay(50);
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}
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static void rtc_end_op(void)
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{
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rtc_nrst_low();
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lasat_ndelay(1000);
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}
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void read_persistent_clock(struct timespec *ts)
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{
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unsigned long word;
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unsigned long flags;
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spin_lock_irqsave(&rtc_lock, flags);
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rtc_init_op();
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rtc_write_byte(READ_TIME_CMD);
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word = rtc_read_word();
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rtc_end_op();
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spin_unlock_irqrestore(&rtc_lock, flags);
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ts->tv_sec = word;
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ts->tv_nsec = 0;
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}
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int rtc_mips_set_mmss(unsigned long time)
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{
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unsigned long flags;
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spin_lock_irqsave(&rtc_lock, flags);
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rtc_init_op();
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rtc_write_byte(SET_TIME_CMD);
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rtc_write_word(time);
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rtc_end_op();
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spin_unlock_irqrestore(&rtc_lock, flags);
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return 0;
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}
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void ds1603_set_trimmer(unsigned int trimval)
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{
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rtc_init_op();
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rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
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| (TRIMMER_SET_CMD));
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rtc_end_op();
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}
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void ds1603_disable(void)
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{
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ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
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}
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void ds1603_enable(void)
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{
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ds1603_set_trimmer(TRIMMER_DEFAULT);
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}
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