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 * 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 0x00 18 #define SD2405AL_REG_T_MIN 0x01 19 #define SD2405AL_REG_T_HOUR 0x02 20 # define SD2405AL_BIT_12H_PM BIT(5) 21 # define SD2405AL_BIT_24H BIT(7) 22 #define SD2405AL_REG_T_WEEK 0x03 23 #define SD2405AL_REG_T_DAY 0x04 24 #define SD2405AL_REG_T_MON 0x05 25 #define SD2405AL_REG_T_YEAR 0x06 26 27 #define SD2405AL_NUM_T_REGS (SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1) 28 29 /* Control registers */ 30 #define SD2405AL_REG_CTR1 0x0F 31 # define SD2405AL_BIT_WRTC2 BIT(2) 32 # define SD2405AL_BIT_WRTC3 BIT(7) 33 #define SD2405AL_REG_CTR2 0x10 34 # define SD2405AL_BIT_WRTC1 BIT(7) 35 #define SD2405AL_REG_CTR3 0x11 36 #define SD2405AL_REG_TTF 0x12 37 #define SD2405AL_REG_CNTDWN 0x13 38 39 /* General RAM */ 40 #define SD2405AL_REG_M_START 0x14 41 #define SD2405AL_REG_M_END 0x1F 42 43 struct sd2405al { 44 struct device *dev; 45 struct rtc_device *rtc; 46 struct regmap *regmap; 47 }; 48 49 static 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 68 static 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 86 static 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 else 103 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 } 119 120 static 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 } 155 156 static const struct rtc_class_ops sd2405al_rtc_ops = { 157 .read_time = sd2405al_read_time, 158 .set_time = sd2405al_set_time, 159 }; 160 161 static const struct regmap_config sd2405al_regmap_conf = { 162 .reg_bits = 8, 163 .val_bits = 8, 164 .max_register = SD2405AL_REG_M_END, 165 }; 166 167 static 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 } 201 202 static const struct i2c_device_id sd2405al_id[] = { 203 { "sd2405al" }, 204 { /* sentinel */ } 205 }; 206 MODULE_DEVICE_TABLE(i2c, sd2405al_id); 207 208 static const __maybe_unused struct of_device_id sd2405al_of_match[] = { 209 { .compatible = "dfrobot,sd2405al" }, 210 { /* sentinel */ } 211 }; 212 MODULE_DEVICE_TABLE(of, sd2405al_of_match); 213 214 static 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 }; 222 223 module_i2c_driver(sd2405al_driver); 224 225 MODULE_AUTHOR("Tóth János <gomba007@gmail.com>"); 226 MODULE_LICENSE("GPL"); 227 MODULE_DESCRIPTION("SD2405AL RTC driver"); 228