drivers/rtc/rtc-sd2405al.c

   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");