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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Real Time Clock (RTC) Driver for sd3078
- * Copyright (C) 2018 Zoro Li
- */
- #include <linux/bcd.h>
- #include <linux/i2c.h>
- #include <linux/module.h>
- #include <linux/regmap.h>
- #include <linux/rtc.h>
- #include <linux/slab.h>
- #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_new = sd3078_probe,
- .id_table = sd3078_id,
- };
- module_i2c_driver(sd3078_driver);
- MODULE_AUTHOR("Dianlong Li <[email protected]>");
- MODULE_DESCRIPTION("SD3078 RTC driver");
- MODULE_LICENSE("GPL v2");
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