1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Real Time Clock (RTC) Driver for sd3078 4 * Copyright (C) 2018 Zoro Li 5 */ 6 7#include <linux/bcd.h> 8#include <linux/i2c.h> 9#include <linux/module.h> 10#include <linux/regmap.h> 11#include <linux/rtc.h> 12#include <linux/slab.h> 13 14#define SD3078_REG_SC 0x00 15#define SD3078_REG_MN 0x01 16#define SD3078_REG_HR 0x02 17#define SD3078_REG_DW 0x03 18#define SD3078_REG_DM 0x04 19#define SD3078_REG_MO 0x05 20#define SD3078_REG_YR 0x06 21 22#define SD3078_REG_CTRL1 0x0f 23#define SD3078_REG_CTRL2 0x10 24#define SD3078_REG_CTRL3 0x11 25 26#define KEY_WRITE1 0x80 27#define KEY_WRITE2 0x04 28#define KEY_WRITE3 0x80 29 30#define NUM_TIME_REGS (SD3078_REG_YR - SD3078_REG_SC + 1) 31 32/* 33 * The sd3078 has write protection 34 * and we can choose whether or not to use it. 35 * Write protection is turned off by default. 36 */ 37#define WRITE_PROTECT_EN 0 38 39struct sd3078 { 40 struct rtc_device *rtc; 41 struct regmap *regmap; 42}; 43 44/* 45 * In order to prevent arbitrary modification of the time register, 46 * when modification of the register, 47 * the "write" bit needs to be written in a certain order. 48 * 1. set WRITE1 bit 49 * 2. set WRITE2 bit 50 * 3. set WRITE3 bit 51 */ 52static void sd3078_enable_reg_write(struct sd3078 *sd3078) 53{ 54 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2, 55 KEY_WRITE1, KEY_WRITE1); 56 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, 57 KEY_WRITE2, KEY_WRITE2); 58 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, 59 KEY_WRITE3, KEY_WRITE3); 60} 61 62#if WRITE_PROTECT_EN 63/* 64 * In order to prevent arbitrary modification of the time register, 65 * we should disable the write function. 66 * when disable write, 67 * the "write" bit needs to be clear in a certain order. 68 * 1. clear WRITE2 bit 69 * 2. clear WRITE3 bit 70 * 3. clear WRITE1 bit 71 */ 72static void sd3078_disable_reg_write(struct sd3078 *sd3078) 73{ 74 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, 75 KEY_WRITE2, 0); 76 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, 77 KEY_WRITE3, 0); 78 regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2, 79 KEY_WRITE1, 0); 80} 81#endif 82 83static int sd3078_rtc_read_time(struct device *dev, struct rtc_time *tm) 84{ 85 unsigned char hour; 86 unsigned char rtc_data[NUM_TIME_REGS] = {0}; 87 struct i2c_client *client = to_i2c_client(dev); 88 struct sd3078 *sd3078 = i2c_get_clientdata(client); 89 int ret; 90 91 ret = regmap_bulk_read(sd3078->regmap, SD3078_REG_SC, rtc_data, 92 NUM_TIME_REGS); 93 if (ret < 0) { 94 dev_err(dev, "reading from RTC failed with err:%d\n", ret); 95 return ret; 96 } 97 98 tm->tm_sec = bcd2bin(rtc_data[SD3078_REG_SC] & 0x7F); 99 tm->tm_min = bcd2bin(rtc_data[SD3078_REG_MN] & 0x7F); 100 101 /* 102 * The sd3078 supports 12/24 hour mode. 103 * When getting time, 104 * we need to convert the 12 hour mode to the 24 hour mode. 105 */ 106 hour = rtc_data[SD3078_REG_HR]; 107 if (hour & 0x80) /* 24H MODE */ 108 tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x3F); 109 else if (hour & 0x20) /* 12H MODE PM */ 110 tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F) + 12; 111 else /* 12H MODE AM */ 112 tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F); 113 114 tm->tm_mday = bcd2bin(rtc_data[SD3078_REG_DM] & 0x3F); 115 tm->tm_wday = rtc_data[SD3078_REG_DW] & 0x07; 116 tm->tm_mon = bcd2bin(rtc_data[SD3078_REG_MO] & 0x1F) - 1; 117 tm->tm_year = bcd2bin(rtc_data[SD3078_REG_YR]) + 100; 118 119 return 0; 120} 121 122static int sd3078_rtc_set_time(struct device *dev, struct rtc_time *tm) 123{ 124 unsigned char rtc_data[NUM_TIME_REGS]; 125 struct i2c_client *client = to_i2c_client(dev); 126 struct sd3078 *sd3078 = i2c_get_clientdata(client); 127 int ret; 128 129 rtc_data[SD3078_REG_SC] = bin2bcd(tm->tm_sec); 130 rtc_data[SD3078_REG_MN] = bin2bcd(tm->tm_min); 131 rtc_data[SD3078_REG_HR] = bin2bcd(tm->tm_hour) | 0x80; 132 rtc_data[SD3078_REG_DM] = bin2bcd(tm->tm_mday); 133 rtc_data[SD3078_REG_DW] = tm->tm_wday & 0x07; 134 rtc_data[SD3078_REG_MO] = bin2bcd(tm->tm_mon) + 1; 135 rtc_data[SD3078_REG_YR] = bin2bcd(tm->tm_year - 100); 136 137#if WRITE_PROTECT_EN 138 sd3078_enable_reg_write(sd3078); 139#endif 140 141 ret = regmap_bulk_write(sd3078->regmap, SD3078_REG_SC, rtc_data, 142 NUM_TIME_REGS); 143 if (ret < 0) { 144 dev_err(dev, "writing to RTC failed with err:%d\n", ret); 145 return ret; 146 } 147 148#if WRITE_PROTECT_EN 149 sd3078_disable_reg_write(sd3078); 150#endif 151 152 return 0; 153} 154 155static const struct rtc_class_ops sd3078_rtc_ops = { 156 .read_time = sd3078_rtc_read_time, 157 .set_time = sd3078_rtc_set_time, 158}; 159 160static const struct regmap_config regmap_config = { 161 .reg_bits = 8, 162 .val_bits = 8, 163 .max_register = 0x11, 164}; 165 166static int sd3078_probe(struct i2c_client *client) 167{ 168 int ret; 169 struct sd3078 *sd3078; 170 171 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 172 return -ENODEV; 173 174 sd3078 = devm_kzalloc(&client->dev, sizeof(*sd3078), GFP_KERNEL); 175 if (!sd3078) 176 return -ENOMEM; 177 178 sd3078->regmap = devm_regmap_init_i2c(client, ®map_config); 179 if (IS_ERR(sd3078->regmap)) { 180 dev_err(&client->dev, "regmap allocation failed\n"); 181 return PTR_ERR(sd3078->regmap); 182 } 183 184 i2c_set_clientdata(client, sd3078); 185 186 sd3078->rtc = devm_rtc_allocate_device(&client->dev); 187 if (IS_ERR(sd3078->rtc)) 188 return PTR_ERR(sd3078->rtc); 189 190 sd3078->rtc->ops = &sd3078_rtc_ops; 191 sd3078->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; 192 sd3078->rtc->range_max = RTC_TIMESTAMP_END_2099; 193 194 ret = devm_rtc_register_device(sd3078->rtc); 195 if (ret) 196 return ret; 197 198 sd3078_enable_reg_write(sd3078); 199 200 return 0; 201} 202 203static const struct i2c_device_id sd3078_id[] = { 204 {"sd3078", 0}, 205 { } 206}; 207MODULE_DEVICE_TABLE(i2c, sd3078_id); 208 209static const __maybe_unused struct of_device_id rtc_dt_match[] = { 210 { .compatible = "whwave,sd3078" }, 211 {}, 212}; 213MODULE_DEVICE_TABLE(of, rtc_dt_match); 214 215static struct i2c_driver sd3078_driver = { 216 .driver = { 217 .name = "sd3078", 218 .of_match_table = of_match_ptr(rtc_dt_match), 219 }, 220 .probe = sd3078_probe, 221 .id_table = sd3078_id, 222}; 223 224module_i2c_driver(sd3078_driver); 225 226MODULE_AUTHOR("Dianlong Li <long17.cool@163.com>"); 227MODULE_DESCRIPTION("SD3078 RTC driver"); 228MODULE_LICENSE("GPL v2"); 229