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