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The sd3078 is a combination RTC and SRAM device with I2C interface. Signed-off-by: Dianlong Li <long17.cool@163.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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// SPDX-License-Identifier: GPL-2.0 | ||
/* | ||
* Real Time Clock (RTC) Driver for sd3078 | ||
* Copyright (C) 2018 Zoro Li | ||
*/ | ||
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#include <linux/bcd.h> | ||
#include <linux/i2c.h> | ||
#include <linux/module.h> | ||
#include <linux/regmap.h> | ||
#include <linux/rtc.h> | ||
#include <linux/slab.h> | ||
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#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 | ||
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#define SD3078_REG_CTRL1 0x0f | ||
#define SD3078_REG_CTRL2 0x10 | ||
#define SD3078_REG_CTRL3 0x11 | ||
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#define KEY_WRITE1 0x80 | ||
#define KEY_WRITE2 0x04 | ||
#define KEY_WRITE3 0x80 | ||
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#define NUM_TIME_REGS (SD3078_REG_YR - SD3078_REG_SC + 1) | ||
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/* | ||
* 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 | ||
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struct sd3078 { | ||
struct rtc_device *rtc; | ||
struct regmap *regmap; | ||
}; | ||
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/* | ||
* 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); | ||
} | ||
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#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 | ||
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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; | ||
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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; | ||
} | ||
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tm->tm_sec = bcd2bin(rtc_data[SD3078_REG_SC] & 0x7F); | ||
tm->tm_min = bcd2bin(rtc_data[SD3078_REG_MN] & 0x7F); | ||
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/* | ||
* 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); | ||
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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; | ||
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return 0; | ||
} | ||
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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; | ||
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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); | ||
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#if WRITE_PROTECT_EN | ||
sd3078_enable_reg_write(sd3078); | ||
#endif | ||
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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; | ||
} | ||
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#if WRITE_PROTECT_EN | ||
sd3078_disable_reg_write(sd3078); | ||
#endif | ||
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return 0; | ||
} | ||
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static const struct rtc_class_ops sd3078_rtc_ops = { | ||
.read_time = sd3078_rtc_read_time, | ||
.set_time = sd3078_rtc_set_time, | ||
}; | ||
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static const struct regmap_config regmap_config = { | ||
.reg_bits = 8, | ||
.val_bits = 8, | ||
.max_register = 0x11, | ||
}; | ||
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static int sd3078_probe(struct i2c_client *client, | ||
const struct i2c_device_id *id) | ||
{ | ||
int ret; | ||
struct sd3078 *sd3078; | ||
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | ||
return -ENODEV; | ||
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sd3078 = devm_kzalloc(&client->dev, sizeof(*sd3078), GFP_KERNEL); | ||
if (!sd3078) | ||
return -ENOMEM; | ||
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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); | ||
} | ||
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i2c_set_clientdata(client, sd3078); | ||
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sd3078->rtc = devm_rtc_allocate_device(&client->dev); | ||
if (IS_ERR(sd3078->rtc)) | ||
return PTR_ERR(sd3078->rtc); | ||
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sd3078->rtc->ops = &sd3078_rtc_ops; | ||
sd3078->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; | ||
sd3078->rtc->range_max = RTC_TIMESTAMP_END_2099; | ||
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ret = rtc_register_device(sd3078->rtc); | ||
if (ret) { | ||
dev_err(&client->dev, "failed to register rtc device\n"); | ||
return ret; | ||
} | ||
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sd3078_enable_reg_write(sd3078); | ||
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return 0; | ||
} | ||
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static const struct i2c_device_id sd3078_id[] = { | ||
{"sd3078", 0}, | ||
{ } | ||
}; | ||
MODULE_DEVICE_TABLE(i2c, sd3078_id); | ||
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static const struct of_device_id rtc_dt_match[] = { | ||
{ .compatible = "whwave,sd3078" }, | ||
{}, | ||
}; | ||
MODULE_DEVICE_TABLE(of, rtc_dt_match); | ||
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struct i2c_driver sd3078_driver = { | ||
.driver = { | ||
.name = "sd3078", | ||
.owner = THIS_MODULE, | ||
.of_match_table = of_match_ptr(rtc_dt_match), | ||
}, | ||
.probe = sd3078_probe, | ||
.id_table = sd3078_id, | ||
}; | ||
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module_i2c_driver(sd3078_driver); | ||
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MODULE_AUTHOR("Dianlong Li <long17.cool@163.com>"); | ||
MODULE_DESCRIPTION("SD3078 RTC driver"); | ||
MODULE_LICENSE("GPL v2"); |