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_clock64(struct timespec64 *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 update_persistent_clock64(struct timespec64 now) 156{ 157 time64_t time = now.tv_sec; 158 unsigned long flags; 159 160 spin_lock_irqsave(&rtc_lock, flags); 161 rtc_init_op(); 162 rtc_write_byte(SET_TIME_CMD); 163 /* 164 * Due to the hardware limitation, we cast to 'unsigned long' type, 165 * so it will overflow in year 2106 on 32-bit machine. 166 */ 167 rtc_write_word((unsigned long)time); 168 rtc_end_op(); 169 spin_unlock_irqrestore(&rtc_lock, flags); 170 171 return 0; 172} 173 174void ds1603_set_trimmer(unsigned int trimval) 175{ 176 rtc_init_op(); 177 rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK) 178 | (TRIMMER_SET_CMD)); 179 rtc_end_op(); 180} 181 182void ds1603_disable(void) 183{ 184 ds1603_set_trimmer(TRIMMER_DISABLE_RTC); 185} 186 187void ds1603_enable(void) 188{ 189 ds1603_set_trimmer(TRIMMER_DEFAULT); 190} 191