0a2abbfd85
There's nothing in the data sheet that says writing to one of the time keeping registers is necessary to start the RTC. It does so at the stop condition of the i2c transfer setting the WRTC bit: Upon initialization or power-up, the WRTC must be set to "1" to enable the RTC. Upon the completion of a valid write (STOP), the RTC starts counting. Moreover, even if such a write to one of the timekeeping registers was necessary, that's exactly what we do anyway just below when we actually write the given struct rtc_time to the device. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Link: https://lore.kernel.org/r/20220921114624.3250848-8-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
265 lines
6.1 KiB
C
265 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* An I2C driver for the Intersil ISL 12022
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*
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* Author: Roman Fietze <roman.fietze@telemotive.de>
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*
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* Based on the Philips PCF8563 RTC
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* by Alessandro Zummo <a.zummo@towertech.it>.
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*/
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#include <linux/i2c.h>
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#include <linux/bcd.h>
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#include <linux/rtc.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/err.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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/* ISL register offsets */
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#define ISL12022_REG_SC 0x00
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#define ISL12022_REG_MN 0x01
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#define ISL12022_REG_HR 0x02
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#define ISL12022_REG_DT 0x03
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#define ISL12022_REG_MO 0x04
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#define ISL12022_REG_YR 0x05
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#define ISL12022_REG_DW 0x06
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#define ISL12022_REG_SR 0x07
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#define ISL12022_REG_INT 0x08
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/* ISL register bits */
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#define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */
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#define ISL12022_SR_LBAT85 (1 << 2)
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#define ISL12022_SR_LBAT75 (1 << 1)
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#define ISL12022_INT_WRTC (1 << 6)
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static struct i2c_driver isl12022_driver;
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struct isl12022 {
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struct rtc_device *rtc;
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bool write_enabled; /* true if write enable is set */
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};
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static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
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uint8_t *data, size_t n)
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{
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struct i2c_msg msgs[] = {
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{
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.addr = client->addr,
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.flags = 0,
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.len = 1,
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.buf = data
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}, /* setup read ptr */
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{
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.addr = client->addr,
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.flags = I2C_M_RD,
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.len = n,
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.buf = data
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}
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};
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int ret;
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data[0] = reg;
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ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
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if (ret != ARRAY_SIZE(msgs)) {
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dev_err(&client->dev, "%s: read error, ret=%d\n",
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__func__, ret);
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return -EIO;
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}
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return 0;
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}
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static int isl12022_write_reg(struct i2c_client *client,
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uint8_t reg, uint8_t val)
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{
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uint8_t data[2] = { reg, val };
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int err;
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err = i2c_master_send(client, data, sizeof(data));
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if (err != sizeof(data)) {
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dev_err(&client->dev,
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"%s: err=%d addr=%02x, data=%02x\n",
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__func__, err, data[0], data[1]);
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return -EIO;
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}
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return 0;
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}
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/*
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* In the routines that deal directly with the isl12022 hardware, we use
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* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
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*/
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static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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uint8_t buf[ISL12022_REG_INT + 1];
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int ret;
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ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
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if (ret)
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return ret;
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if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
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dev_warn(dev,
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"voltage dropped below %u%%, "
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"date and time is not reliable.\n",
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buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
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}
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dev_dbg(dev,
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"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
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"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
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"sr=%02x, int=%02x",
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__func__,
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buf[ISL12022_REG_SC],
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buf[ISL12022_REG_MN],
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buf[ISL12022_REG_HR],
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buf[ISL12022_REG_DT],
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buf[ISL12022_REG_MO],
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buf[ISL12022_REG_YR],
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buf[ISL12022_REG_DW],
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buf[ISL12022_REG_SR],
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buf[ISL12022_REG_INT]);
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tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
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tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
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tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
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tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
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tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
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tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
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tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
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dev_dbg(dev, "%s: %ptR\n", __func__, tm);
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return 0;
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}
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static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct isl12022 *isl12022 = dev_get_drvdata(dev);
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size_t i;
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int ret;
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uint8_t buf[ISL12022_REG_DW + 1];
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dev_dbg(dev, "%s: %ptR\n", __func__, tm);
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if (!isl12022->write_enabled) {
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ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
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if (ret)
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return ret;
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/* Check if WRTC (write rtc enable) is set factory default is
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* 0 (not set) */
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if (!(buf[0] & ISL12022_INT_WRTC)) {
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/* Set the write enable bit. */
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ret = isl12022_write_reg(client,
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ISL12022_REG_INT,
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buf[0] | ISL12022_INT_WRTC);
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if (ret)
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return ret;
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}
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isl12022->write_enabled = true;
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}
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/* hours, minutes and seconds */
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buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
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buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
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buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
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buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
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/* month, 1 - 12 */
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buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
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/* year and century */
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buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
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buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
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/* write register's data */
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for (i = 0; i < ARRAY_SIZE(buf); i++) {
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ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
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buf[ISL12022_REG_SC + i]);
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if (ret)
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return -EIO;
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}
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return 0;
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}
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static const struct rtc_class_ops isl12022_rtc_ops = {
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.read_time = isl12022_rtc_read_time,
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.set_time = isl12022_rtc_set_time,
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};
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static int isl12022_probe(struct i2c_client *client)
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{
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struct isl12022 *isl12022;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
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GFP_KERNEL);
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if (!isl12022)
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return -ENOMEM;
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dev_set_drvdata(&client->dev, isl12022);
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isl12022->rtc = devm_rtc_allocate_device(&client->dev);
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if (IS_ERR(isl12022->rtc))
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return PTR_ERR(isl12022->rtc);
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isl12022->rtc->ops = &isl12022_rtc_ops;
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isl12022->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
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isl12022->rtc->range_max = RTC_TIMESTAMP_END_2099;
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return devm_rtc_register_device(isl12022->rtc);
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}
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#ifdef CONFIG_OF
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static const struct of_device_id isl12022_dt_match[] = {
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{ .compatible = "isl,isl12022" }, /* for backward compat., don't use */
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{ .compatible = "isil,isl12022" },
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{ },
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};
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MODULE_DEVICE_TABLE(of, isl12022_dt_match);
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#endif
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static const struct i2c_device_id isl12022_id[] = {
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{ "isl12022", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, isl12022_id);
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static struct i2c_driver isl12022_driver = {
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.driver = {
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.name = "rtc-isl12022",
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#ifdef CONFIG_OF
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.of_match_table = of_match_ptr(isl12022_dt_match),
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#endif
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},
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.probe_new = isl12022_probe,
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.id_table = isl12022_id,
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};
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module_i2c_driver(isl12022_driver);
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MODULE_AUTHOR("roman.fietze@telemotive.de");
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MODULE_DESCRIPTION("ISL 12022 RTC driver");
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MODULE_LICENSE("GPL");
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