// SPDX-License-Identifier: GPL-2.0 /* * Real Time Clock (RTC) Driver for sd3078 * Copyright (C) 2018 Zoro Li */ #include #include #include #include #include #include #define SD3078_REG_SC 0x00 #define SD3078_REG_MN 0x01 #define SD3078_REG_HR 0x02 #define SD3078_REG_DW 0x03 #define SD3078_REG_DM 0x04 #define SD3078_REG_MO 0x05 #define SD3078_REG_YR 0x06 #define SD3078_REG_CTRL1 0x0f #define SD3078_REG_CTRL2 0x10 #define SD3078_REG_CTRL3 0x11 #define KEY_WRITE1 0x80 #define KEY_WRITE2 0x04 #define KEY_WRITE3 0x80 #define NUM_TIME_REGS (SD3078_REG_YR - SD3078_REG_SC + 1) /* * The sd3078 has write protection * and we can choose whether or not to use it. * Write protection is turned off by default. */ #define WRITE_PROTECT_EN 0 struct sd3078 { struct rtc_device *rtc; struct regmap *regmap; }; /* * In order to prevent arbitrary modification of the time register, * when modification of the register, * the "write" bit needs to be written in a certain order. * 1. set WRITE1 bit * 2. set WRITE2 bit * 3. set WRITE3 bit */ static void sd3078_enable_reg_write(struct sd3078 *sd3078) { regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2, KEY_WRITE1, KEY_WRITE1); regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, KEY_WRITE2, KEY_WRITE2); regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, KEY_WRITE3, KEY_WRITE3); } #if WRITE_PROTECT_EN /* * In order to prevent arbitrary modification of the time register, * we should disable the write function. * when disable write, * the "write" bit needs to be clear in a certain order. * 1. clear WRITE2 bit * 2. clear WRITE3 bit * 3. clear WRITE1 bit */ static void sd3078_disable_reg_write(struct sd3078 *sd3078) { regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, KEY_WRITE2, 0); regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1, KEY_WRITE3, 0); regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2, KEY_WRITE1, 0); } #endif static int sd3078_rtc_read_time(struct device *dev, struct rtc_time *tm) { unsigned char hour; unsigned char rtc_data[NUM_TIME_REGS] = {0}; struct i2c_client *client = to_i2c_client(dev); struct sd3078 *sd3078 = i2c_get_clientdata(client); int ret; ret = regmap_bulk_read(sd3078->regmap, SD3078_REG_SC, rtc_data, NUM_TIME_REGS); if (ret < 0) { dev_err(dev, "reading from RTC failed with err:%d\n", ret); return ret; } tm->tm_sec = bcd2bin(rtc_data[SD3078_REG_SC] & 0x7F); tm->tm_min = bcd2bin(rtc_data[SD3078_REG_MN] & 0x7F); /* * The sd3078 supports 12/24 hour mode. * When getting time, * we need to convert the 12 hour mode to the 24 hour mode. */ hour = rtc_data[SD3078_REG_HR]; if (hour & 0x80) /* 24H MODE */ tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x3F); else if (hour & 0x20) /* 12H MODE PM */ tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F) + 12; else /* 12H MODE AM */ tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F); tm->tm_mday = bcd2bin(rtc_data[SD3078_REG_DM] & 0x3F); tm->tm_wday = rtc_data[SD3078_REG_DW] & 0x07; tm->tm_mon = bcd2bin(rtc_data[SD3078_REG_MO] & 0x1F) - 1; tm->tm_year = bcd2bin(rtc_data[SD3078_REG_YR]) + 100; return 0; } static int sd3078_rtc_set_time(struct device *dev, struct rtc_time *tm) { unsigned char rtc_data[NUM_TIME_REGS]; struct i2c_client *client = to_i2c_client(dev); struct sd3078 *sd3078 = i2c_get_clientdata(client); int ret; rtc_data[SD3078_REG_SC] = bin2bcd(tm->tm_sec); rtc_data[SD3078_REG_MN] = bin2bcd(tm->tm_min); rtc_data[SD3078_REG_HR] = bin2bcd(tm->tm_hour) | 0x80; rtc_data[SD3078_REG_DM] = bin2bcd(tm->tm_mday); rtc_data[SD3078_REG_DW] = tm->tm_wday & 0x07; rtc_data[SD3078_REG_MO] = bin2bcd(tm->tm_mon) + 1; rtc_data[SD3078_REG_YR] = bin2bcd(tm->tm_year - 100); #if WRITE_PROTECT_EN sd3078_enable_reg_write(sd3078); #endif ret = regmap_bulk_write(sd3078->regmap, SD3078_REG_SC, rtc_data, NUM_TIME_REGS); if (ret < 0) { dev_err(dev, "writing to RTC failed with err:%d\n", ret); return ret; } #if WRITE_PROTECT_EN sd3078_disable_reg_write(sd3078); #endif return 0; } static const struct rtc_class_ops sd3078_rtc_ops = { .read_time = sd3078_rtc_read_time, .set_time = sd3078_rtc_set_time, }; static const struct regmap_config regmap_config = { .reg_bits = 8, .val_bits = 8, .max_register = 0x11, }; static int sd3078_probe(struct i2c_client *client) { int ret; struct sd3078 *sd3078; if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) return -ENODEV; sd3078 = devm_kzalloc(&client->dev, sizeof(*sd3078), GFP_KERNEL); if (!sd3078) return -ENOMEM; sd3078->regmap = devm_regmap_init_i2c(client, ®map_config); if (IS_ERR(sd3078->regmap)) { dev_err(&client->dev, "regmap allocation failed\n"); return PTR_ERR(sd3078->regmap); } i2c_set_clientdata(client, sd3078); sd3078->rtc = devm_rtc_allocate_device(&client->dev); if (IS_ERR(sd3078->rtc)) return PTR_ERR(sd3078->rtc); sd3078->rtc->ops = &sd3078_rtc_ops; sd3078->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; sd3078->rtc->range_max = RTC_TIMESTAMP_END_2099; ret = devm_rtc_register_device(sd3078->rtc); if (ret) return ret; sd3078_enable_reg_write(sd3078); return 0; } static const struct i2c_device_id sd3078_id[] = { {"sd3078", 0}, { } }; MODULE_DEVICE_TABLE(i2c, sd3078_id); static const __maybe_unused struct of_device_id rtc_dt_match[] = { { .compatible = "whwave,sd3078" }, {}, }; MODULE_DEVICE_TABLE(of, rtc_dt_match); static struct i2c_driver sd3078_driver = { .driver = { .name = "sd3078", .of_match_table = of_match_ptr(rtc_dt_match), }, .probe = sd3078_probe, .id_table = sd3078_id, }; module_i2c_driver(sd3078_driver); MODULE_AUTHOR("Dianlong Li "); MODULE_DESCRIPTION("SD3078 RTC driver"); MODULE_LICENSE("GPL v2");