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1// SPDX-License-Identifier: GPL-2.02/*3 * Real Time Clock (RTC) Driver for sd30784 * Copyright (C) 2018 Zoro Li5 */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 0x0015#define SD3078_REG_MN 0x0116#define SD3078_REG_HR 0x0217#define SD3078_REG_DW 0x0318#define SD3078_REG_DM 0x0419#define SD3078_REG_MO 0x0520#define SD3078_REG_YR 0x0621 22#define SD3078_REG_CTRL1 0x0f23#define SD3078_REG_CTRL2 0x1024#define SD3078_REG_CTRL3 0x1125 26#define KEY_WRITE1 0x8027#define KEY_WRITE2 0x0428#define KEY_WRITE3 0x8029 30#define NUM_TIME_REGS (SD3078_REG_YR - SD3078_REG_SC + 1)31 32/*33 * The sd3078 has write protection34 * and we can choose whether or not to use it.35 * Write protection is turned off by default.36 */37#define WRITE_PROTECT_EN 038 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 bit49 * 2. set WRITE2 bit50 * 3. set WRITE3 bit51 */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_EN63/*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 bit69 * 2. clear WRITE3 bit70 * 3. clear WRITE1 bit71 */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#endif82 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_EN138 sd3078_enable_reg_write(sd3078);139#endif140 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_EN149 sd3078_disable_reg_write(sd3078);150#endif151 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" },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