// 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" },
{ }
};
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 <[email protected]>");
MODULE_DESCRIPTION("SD3078 RTC driver");
MODULE_LICENSE("GPL v2");
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