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Diffstat (limited to '')
| -rw-r--r-- | drivers/rtc/rtc-sd3078.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-sd3078.c b/drivers/rtc/rtc-sd3078.c new file mode 100644 index 000000000..e2f90d768 --- /dev/null +++ b/drivers/rtc/rtc-sd3078.c @@ -0,0 +1,228 @@ +// 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 <long17.cool@163.com>"); +MODULE_DESCRIPTION("SD3078 RTC driver"); +MODULE_LICENSE("GPL v2"); |