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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * RTC driver for the SD2405AL Real-Time Clock4 *5 * Datasheet:6 * https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf7 *8 * Copyright (C) 2024 Tóth János <gomba007@gmail.com>9 */10 11#include <linux/bcd.h>12#include <linux/i2c.h>13#include <linux/regmap.h>14#include <linux/rtc.h>15 16/* Real time clock registers */17#define SD2405AL_REG_T_SEC 0x0018#define SD2405AL_REG_T_MIN 0x0119#define SD2405AL_REG_T_HOUR 0x0220# define SD2405AL_BIT_12H_PM BIT(5)21# define SD2405AL_BIT_24H BIT(7)22#define SD2405AL_REG_T_WEEK 0x0323#define SD2405AL_REG_T_DAY 0x0424#define SD2405AL_REG_T_MON 0x0525#define SD2405AL_REG_T_YEAR 0x0626 27#define SD2405AL_NUM_T_REGS (SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1)28 29/* Control registers */30#define SD2405AL_REG_CTR1 0x0F31# define SD2405AL_BIT_WRTC2 BIT(2)32# define SD2405AL_BIT_WRTC3 BIT(7)33#define SD2405AL_REG_CTR2 0x1034# define SD2405AL_BIT_WRTC1 BIT(7)35#define SD2405AL_REG_CTR3 0x1136#define SD2405AL_REG_TTF 0x1237#define SD2405AL_REG_CNTDWN 0x1338 39/* General RAM */40#define SD2405AL_REG_M_START 0x1441#define SD2405AL_REG_M_END 0x1F42 43struct sd2405al {44 struct device *dev;45 struct rtc_device *rtc;46 struct regmap *regmap;47};48 49static int sd2405al_enable_reg_write(struct sd2405al *sd2405al)50{51 int ret;52 53 /* order of writes is important */54 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,55 SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1);56 if (ret < 0)57 return ret;58 59 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,60 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3,61 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3);62 if (ret < 0)63 return ret;64 65 return 0;66}67 68static int sd2405al_disable_reg_write(struct sd2405al *sd2405al)69{70 int ret;71 72 /* order of writes is important */73 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,74 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00);75 if (ret < 0)76 return ret;77 78 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,79 SD2405AL_BIT_WRTC1, 0x00);80 if (ret < 0)81 return ret;82 83 return 0;84}85 86static int sd2405al_read_time(struct device *dev, struct rtc_time *time)87{88 u8 data[SD2405AL_NUM_T_REGS] = { 0 };89 struct sd2405al *sd2405al = dev_get_drvdata(dev);90 int ret;91 92 ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data,93 SD2405AL_NUM_T_REGS);94 if (ret < 0)95 return ret;96 97 time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F);98 time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F);99 100 if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H)101 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F);102 else103 if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM)104 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]105 & 0x1F) + 12;106 else /* 12 hour mode, AM */107 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]108 & 0x1F);109 110 time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07);111 time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F);112 time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1;113 time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100;114 115 dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday);116 117 return 0;118}119 120static int sd2405al_set_time(struct device *dev, struct rtc_time *time)121{122 u8 data[SD2405AL_NUM_T_REGS];123 struct sd2405al *sd2405al = dev_get_drvdata(dev);124 int ret;125 126 data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec);127 data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min);128 data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H;129 data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday);130 data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday);131 data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1;132 data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100);133 134 ret = sd2405al_enable_reg_write(sd2405al);135 if (ret < 0)136 return ret;137 138 ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data,139 SD2405AL_NUM_T_REGS);140 if (ret < 0)141 return ret;142 143 ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00);144 if (ret < 0)145 return ret;146 147 ret = sd2405al_disable_reg_write(sd2405al);148 if (ret < 0)149 return ret;150 151 dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday);152 153 return 0;154}155 156static const struct rtc_class_ops sd2405al_rtc_ops = {157 .read_time = sd2405al_read_time,158 .set_time = sd2405al_set_time,159};160 161static const struct regmap_config sd2405al_regmap_conf = {162 .reg_bits = 8,163 .val_bits = 8,164 .max_register = SD2405AL_REG_M_END,165};166 167static int sd2405al_probe(struct i2c_client *client)168{169 struct sd2405al *sd2405al;170 int ret;171 172 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))173 return -ENODEV;174 175 sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL);176 if (!sd2405al)177 return -ENOMEM;178 179 sd2405al->dev = &client->dev;180 181 sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf);182 if (IS_ERR(sd2405al->regmap))183 return PTR_ERR(sd2405al->regmap);184 185 sd2405al->rtc = devm_rtc_allocate_device(&client->dev);186 if (IS_ERR(sd2405al->rtc))187 return PTR_ERR(sd2405al->rtc);188 189 sd2405al->rtc->ops = &sd2405al_rtc_ops;190 sd2405al->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;191 sd2405al->rtc->range_max = RTC_TIMESTAMP_END_2099;192 193 dev_set_drvdata(&client->dev, sd2405al);194 195 ret = devm_rtc_register_device(sd2405al->rtc);196 if (ret < 0)197 return ret;198 199 return 0;200}201 202static const struct i2c_device_id sd2405al_id[] = {203 { "sd2405al" },204 { /* sentinel */ }205};206MODULE_DEVICE_TABLE(i2c, sd2405al_id);207 208static const __maybe_unused struct of_device_id sd2405al_of_match[] = {209 { .compatible = "dfrobot,sd2405al" },210 { /* sentinel */ }211};212MODULE_DEVICE_TABLE(of, sd2405al_of_match);213 214static struct i2c_driver sd2405al_driver = {215 .driver = {216 .name = "sd2405al",217 .of_match_table = of_match_ptr(sd2405al_of_match),218 },219 .probe = sd2405al_probe,220 .id_table = sd2405al_id,221};222 223module_i2c_driver(sd2405al_driver);224 225MODULE_AUTHOR("Tóth János <gomba007@gmail.com>");226MODULE_LICENSE("GPL");227MODULE_DESCRIPTION("SD2405AL RTC driver");228