1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * RTC driver for the SD2405AL Real-Time Clock 4 * 5 * Datasheet: 6 * https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf 7 * 8 * I2C slave address: 0x32 9 * 10 * Copyright (C) 2024-2025 Tóth János <gomba007@gmail.com> 11 */ 12 13 #include <linux/bcd.h> 14 #include <linux/i2c.h> 15 #include <linux/regmap.h> 16 #include <linux/rtc.h> 17 18 /* Real time clock registers */ 19 #define SD2405AL_REG_T_SEC 0x00 20 #define SD2405AL_REG_T_MIN 0x01 21 #define SD2405AL_REG_T_HOUR 0x02 22 # define SD2405AL_BIT_12H_PM BIT(5) 23 # define SD2405AL_BIT_24H BIT(7) 24 #define SD2405AL_REG_T_WEEK 0x03 25 #define SD2405AL_REG_T_DAY 0x04 26 #define SD2405AL_REG_T_MON 0x05 27 #define SD2405AL_REG_T_YEAR 0x06 28 29 #define SD2405AL_NUM_T_REGS (SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1) 30 31 /* Control registers */ 32 #define SD2405AL_REG_CTR1 0x0F 33 # define SD2405AL_BIT_WRTC2 BIT(2) 34 # define SD2405AL_BIT_WRTC3 BIT(7) 35 #define SD2405AL_REG_CTR2 0x10 36 # define SD2405AL_BIT_WRTC1 BIT(7) 37 #define SD2405AL_REG_CTR3 0x11 38 #define SD2405AL_REG_TTF 0x12 39 #define SD2405AL_REG_CNTDWN 0x13 40 41 /* General RAM */ 42 #define SD2405AL_REG_M_START 0x14 43 #define SD2405AL_REG_M_END 0x1F 44 45 struct sd2405al { 46 struct device *dev; 47 struct regmap *regmap; 48 }; 49 50 static int sd2405al_enable_reg_write(struct sd2405al *sd2405al) 51 { 52 int ret; 53 54 /* order of writes is important */ 55 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2, 56 SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1); 57 if (ret < 0) 58 return ret; 59 60 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1, 61 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 62 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3); 63 if (ret < 0) 64 return ret; 65 66 return 0; 67 } 68 69 static int sd2405al_disable_reg_write(struct sd2405al *sd2405al) 70 { 71 int ret; 72 73 /* order of writes is important */ 74 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1, 75 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00); 76 if (ret < 0) 77 return ret; 78 79 ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2, 80 SD2405AL_BIT_WRTC1, 0x00); 81 if (ret < 0) 82 return ret; 83 84 return 0; 85 } 86 87 static int sd2405al_read_time(struct device *dev, struct rtc_time *time) 88 { 89 u8 data[SD2405AL_NUM_T_REGS] = { 0 }; 90 struct sd2405al *sd2405al = dev_get_drvdata(dev); 91 int ret; 92 93 ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data, 94 SD2405AL_NUM_T_REGS); 95 if (ret < 0) 96 return ret; 97 98 time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F); 99 time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F); 100 101 if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H) 102 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F); 103 else 104 if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM) 105 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] 106 & 0x1F) + 12; 107 else /* 12 hour mode, AM */ 108 time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] 109 & 0x1F); 110 111 time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07); 112 time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F); 113 time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1; 114 time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100; 115 116 dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday); 117 118 return 0; 119 } 120 121 static int sd2405al_set_time(struct device *dev, struct rtc_time *time) 122 { 123 u8 data[SD2405AL_NUM_T_REGS]; 124 struct sd2405al *sd2405al = dev_get_drvdata(dev); 125 int ret; 126 127 data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec); 128 data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min); 129 data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H; 130 data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday); 131 data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday); 132 data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1; 133 data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100); 134 135 ret = sd2405al_enable_reg_write(sd2405al); 136 if (ret < 0) 137 return ret; 138 139 ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data, 140 SD2405AL_NUM_T_REGS); 141 if (ret < 0) 142 return ret; 143 144 ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00); 145 if (ret < 0) 146 return ret; 147 148 ret = sd2405al_disable_reg_write(sd2405al); 149 if (ret < 0) 150 return ret; 151 152 dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday); 153 154 return 0; 155 } 156 157 static const struct rtc_class_ops sd2405al_rtc_ops = { 158 .read_time = sd2405al_read_time, 159 .set_time = sd2405al_set_time, 160 }; 161 162 static const struct regmap_config sd2405al_regmap_conf = { 163 .reg_bits = 8, 164 .val_bits = 8, 165 .max_register = SD2405AL_REG_M_END, 166 }; 167 168 static int sd2405al_probe(struct i2c_client *client) 169 { 170 struct sd2405al *sd2405al; 171 struct rtc_device *rtc; 172 int ret; 173 174 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 175 return -ENODEV; 176 177 sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL); 178 if (!sd2405al) 179 return -ENOMEM; 180 181 sd2405al->dev = &client->dev; 182 183 sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf); 184 if (IS_ERR(sd2405al->regmap)) 185 return PTR_ERR(sd2405al->regmap); 186 187 rtc = devm_rtc_allocate_device(&client->dev); 188 if (IS_ERR(rtc)) 189 return PTR_ERR(rtc); 190 191 rtc->ops = &sd2405al_rtc_ops; 192 rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; 193 rtc->range_max = RTC_TIMESTAMP_END_2099; 194 195 dev_set_drvdata(&client->dev, sd2405al); 196 197 ret = devm_rtc_register_device(rtc); 198 if (ret < 0) 199 return ret; 200 201 return 0; 202 } 203 204 static const struct i2c_device_id sd2405al_id[] = { 205 { "sd2405al" }, 206 { /* sentinel */ } 207 }; 208 MODULE_DEVICE_TABLE(i2c, sd2405al_id); 209 210 static const __maybe_unused struct of_device_id sd2405al_of_match[] = { 211 { .compatible = "dfrobot,sd2405al" }, 212 { /* sentinel */ } 213 }; 214 MODULE_DEVICE_TABLE(of, sd2405al_of_match); 215 216 static struct i2c_driver sd2405al_driver = { 217 .driver = { 218 .name = "sd2405al", 219 .of_match_table = of_match_ptr(sd2405al_of_match), 220 }, 221 .probe = sd2405al_probe, 222 .id_table = sd2405al_id, 223 }; 224 225 module_i2c_driver(sd2405al_driver); 226 227 MODULE_AUTHOR("Tóth János <gomba007@gmail.com>"); 228 MODULE_LICENSE("GPL"); 229 MODULE_DESCRIPTION("SD2405AL RTC driver"); 230