LXR linux/arch/mips/lasat/ds1603.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Dallas Semiconductors 1603 RTC driver
   4 *
   5 * Brian Murphy <brian@murphy.dk>
   6 *
   7 */
   8#include <linux/kernel.h>
   9#include <asm/lasat/lasat.h>
  10#include <linux/delay.h>
  11#include <asm/lasat/ds1603.h>
  12#include <asm/time.h>
  13
  14#include "ds1603.h"
  15
  16#define READ_TIME_CMD 0x81
  17#define SET_TIME_CMD 0x80
  18#define TRIMMER_SET_CMD 0xC0
  19#define TRIMMER_VALUE_MASK 0x38
  20#define TRIMMER_SHIFT 3
  21
  22struct ds_defs *ds1603;
  23
  24/* HW specific register functions */
  25static void rtc_reg_write(unsigned long val)
  26{
  27        *ds1603->reg = val;
  28}
  29
  30static unsigned long rtc_reg_read(void)
  31{
  32        unsigned long tmp = *ds1603->reg;
  33        return tmp;
  34}
  35
  36static unsigned long rtc_datareg_read(void)
  37{
  38        unsigned long tmp = *ds1603->data_reg;
  39        return tmp;
  40}
  41
  42static void rtc_nrst_high(void)
  43{
  44        rtc_reg_write(rtc_reg_read() | ds1603->rst);
  45}
  46
  47static void rtc_nrst_low(void)
  48{
  49        rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
  50}
  51
  52static void rtc_cycle_clock(unsigned long data)
  53{
  54        data |= ds1603->clk;
  55        rtc_reg_write(data);
  56        lasat_ndelay(250);
  57        if (ds1603->data_reversed)
  58                data &= ~ds1603->data;
  59        else
  60                data |= ds1603->data;
  61        data &= ~ds1603->clk;
  62        rtc_reg_write(data);
  63        lasat_ndelay(250 + ds1603->huge_delay);
  64}
  65
  66static void rtc_write_databit(unsigned int bit)
  67{
  68        unsigned long data = rtc_reg_read();
  69        if (ds1603->data_reversed)
  70                bit = !bit;
  71        if (bit)
  72                data |= ds1603->data;
  73        else
  74                data &= ~ds1603->data;
  75
  76        rtc_reg_write(data);
  77        lasat_ndelay(50 + ds1603->huge_delay);
  78        rtc_cycle_clock(data);
  79}
  80
  81static unsigned int rtc_read_databit(void)
  82{
  83        unsigned int data;
  84
  85        data = (rtc_datareg_read() & (1 << ds1603->data_read_shift))
  86                >> ds1603->data_read_shift;
  87        rtc_cycle_clock(rtc_reg_read());
  88        return data;
  89}
  90
  91static void rtc_write_byte(unsigned int byte)
  92{
  93        int i;
  94
  95        for (i = 0; i <= 7; i++) {
  96                rtc_write_databit(byte & 1L);
  97                byte >>= 1;
  98        }
  99}
 100
 101static void rtc_write_word(unsigned long word)
 102{
 103        int i;
 104
 105        for (i = 0; i <= 31; i++) {
 106                rtc_write_databit(word & 1L);
 107                word >>= 1;
 108        }
 109}
 110
 111static unsigned long rtc_read_word(void)
 112{
 113        int i;
 114        unsigned long word = 0;
 115        unsigned long shift = 0;
 116
 117        for (i = 0; i <= 31; i++) {
 118                word |= rtc_read_databit() << shift;
 119                shift++;
 120        }
 121        return word;
 122}
 123
 124static void rtc_init_op(void)
 125{
 126        rtc_nrst_high();
 127
 128        rtc_reg_write(rtc_reg_read() & ~ds1603->clk);
 129
 130        lasat_ndelay(50);
 131}
 132
 133static void rtc_end_op(void)
 134{
 135        rtc_nrst_low();
 136        lasat_ndelay(1000);
 137}
 138
 139void read_persistent_clock(struct timespec *ts)
 140{
 141        unsigned long word;
 142        unsigned long flags;
 143
 144        spin_lock_irqsave(&rtc_lock, flags);
 145        rtc_init_op();
 146        rtc_write_byte(READ_TIME_CMD);
 147        word = rtc_read_word();
 148        rtc_end_op();
 149        spin_unlock_irqrestore(&rtc_lock, flags);
 150
 151        ts->tv_sec = word;
 152        ts->tv_nsec = 0;
 153}
 154
 155int rtc_mips_set_mmss(unsigned long time)
 156{
 157        unsigned long flags;
 158
 159        spin_lock_irqsave(&rtc_lock, flags);
 160        rtc_init_op();
 161        rtc_write_byte(SET_TIME_CMD);
 162        rtc_write_word(time);
 163        rtc_end_op();
 164        spin_unlock_irqrestore(&rtc_lock, flags);
 165
 166        return 0;
 167}
 168
 169void ds1603_set_trimmer(unsigned int trimval)
 170{
 171        rtc_init_op();
 172        rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
 173                        | (TRIMMER_SET_CMD));
 174        rtc_end_op();
 175}
 176
 177void ds1603_disable(void)
 178{
 179        ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
 180}
 181
 182void ds1603_enable(void)
 183{
 184        ds1603_set_trimmer(TRIMMER_DEFAULT);
 185}
 186