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1// SPDX-License-Identifier: GPL-2.0-only2/* rtc-ds1347.c3 *4 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible5 * Real Time Clock6 *7 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>8 */9 10#include <linux/init.h>11#include <linux/module.h>12#include <linux/device.h>13#include <linux/platform_device.h>14#include <linux/rtc.h>15#include <linux/spi/spi.h>16#include <linux/bcd.h>17#include <linux/regmap.h>18 19/* Registers in ds1347 rtc */20 21#define DS1347_SECONDS_REG 0x0122#define DS1347_MINUTES_REG 0x0323#define DS1347_HOURS_REG 0x0524#define DS1347_DATE_REG 0x0725#define DS1347_MONTH_REG 0x0926#define DS1347_DAY_REG 0x0B27#define DS1347_YEAR_REG 0x0D28#define DS1347_CONTROL_REG 0x0F29#define DS1347_CENTURY_REG 0x1330#define DS1347_STATUS_REG 0x1731#define DS1347_CLOCK_BURST 0x3F32 33#define DS1347_WP_BIT BIT(7)34 35#define DS1347_NEOSC_BIT BIT(7)36#define DS1347_OSF_BIT BIT(2)37 38static const struct regmap_range ds1347_ranges[] = {39 {40 .range_min = DS1347_SECONDS_REG,41 .range_max = DS1347_STATUS_REG,42 },43};44 45static const struct regmap_access_table ds1347_access_table = {46 .yes_ranges = ds1347_ranges,47 .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),48};49 50static int ds1347_read_time(struct device *dev, struct rtc_time *dt)51{52 struct regmap *map = dev_get_drvdata(dev);53 unsigned int status, century, secs;54 unsigned char buf[8];55 int err;56 57 err = regmap_read(map, DS1347_STATUS_REG, &status);58 if (err)59 return err;60 61 if (status & DS1347_OSF_BIT)62 return -EINVAL;63 64 do {65 err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);66 if (err)67 return err;68 69 err = regmap_read(map, DS1347_CENTURY_REG, ¢ury);70 if (err)71 return err;72 73 err = regmap_read(map, DS1347_SECONDS_REG, &secs);74 if (err)75 return err;76 } while (buf[0] != secs);77 78 dt->tm_sec = bcd2bin(buf[0]);79 dt->tm_min = bcd2bin(buf[1] & 0x7f);80 dt->tm_hour = bcd2bin(buf[2] & 0x3F);81 dt->tm_mday = bcd2bin(buf[3]);82 dt->tm_mon = bcd2bin(buf[4]) - 1;83 dt->tm_wday = bcd2bin(buf[5]) - 1;84 dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;85 86 return 0;87}88 89static int ds1347_set_time(struct device *dev, struct rtc_time *dt)90{91 struct regmap *map = dev_get_drvdata(dev);92 unsigned int century;93 unsigned char buf[8];94 int err;95 96 err = regmap_update_bits(map, DS1347_STATUS_REG,97 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);98 if (err)99 return err;100 101 buf[0] = bin2bcd(dt->tm_sec);102 buf[1] = bin2bcd(dt->tm_min);103 buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);104 buf[3] = bin2bcd(dt->tm_mday);105 buf[4] = bin2bcd(dt->tm_mon + 1);106 buf[5] = bin2bcd(dt->tm_wday + 1);107 buf[6] = bin2bcd(dt->tm_year % 100);108 buf[7] = bin2bcd(0x00);109 110 err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);111 if (err)112 return err;113 114 century = (dt->tm_year / 100) + 19;115 err = regmap_write(map, DS1347_CENTURY_REG, bin2bcd(century));116 if (err)117 return err;118 119 return regmap_update_bits(map, DS1347_STATUS_REG,120 DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);121}122 123static const struct rtc_class_ops ds1347_rtc_ops = {124 .read_time = ds1347_read_time,125 .set_time = ds1347_set_time,126};127 128static int ds1347_probe(struct spi_device *spi)129{130 struct rtc_device *rtc;131 struct regmap_config config;132 struct regmap *map;133 int err;134 135 memset(&config, 0, sizeof(config));136 config.reg_bits = 8;137 config.val_bits = 8;138 config.read_flag_mask = 0x80;139 config.max_register = 0x3F;140 config.wr_table = &ds1347_access_table;141 142 /* spi setup with ds1347 in mode 3 and bits per word as 8 */143 spi->mode = SPI_MODE_3;144 spi->bits_per_word = 8;145 spi_setup(spi);146 147 map = devm_regmap_init_spi(spi, &config);148 149 if (IS_ERR(map)) {150 dev_err(&spi->dev, "ds1347 regmap init spi failed\n");151 return PTR_ERR(map);152 }153 154 spi_set_drvdata(spi, map);155 156 /* Disable the write protect of rtc */157 err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);158 if (err)159 return err;160 161 rtc = devm_rtc_allocate_device(&spi->dev);162 if (IS_ERR(rtc))163 return PTR_ERR(rtc);164 165 rtc->ops = &ds1347_rtc_ops;166 rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;167 rtc->range_max = RTC_TIMESTAMP_END_9999;168 169 return devm_rtc_register_device(rtc);170}171 172static struct spi_driver ds1347_driver = {173 .driver = {174 .name = "ds1347",175 },176 .probe = ds1347_probe,177};178 179module_spi_driver(ds1347_driver);180 181MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");182MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");183MODULE_LICENSE("GPL v2");184