287 lines
6.8 KiB
C
287 lines
6.8 KiB
C
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// 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(&client->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(&client->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(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
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"mday=%d, mon=%d, year=%d, wday=%d\n",
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__func__,
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tm->tm_sec, tm->tm_min, tm->tm_hour,
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tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
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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 = i2c_get_clientdata(client);
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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(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
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"mday=%d, mon=%d, year=%d, wday=%d\n",
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__func__,
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tm->tm_sec, tm->tm_min, tm->tm_hour,
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tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
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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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dev_info(&client->dev,
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"init write enable and 24 hour format\n");
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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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/* Write to any RTC register to start RTC, we use the
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* HR register, setting the MIL bit to use the 24 hour
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* format. */
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ret = isl12022_read_regs(client, ISL12022_REG_HR,
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buf, 1);
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if (ret)
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return ret;
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ret = isl12022_write_reg(client,
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ISL12022_REG_HR,
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buf[0] | ISL12022_HR_MIL);
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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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const struct i2c_device_id *id)
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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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i2c_set_clientdata(client, isl12022);
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isl12022->rtc = devm_rtc_device_register(&client->dev,
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isl12022_driver.driver.name,
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&isl12022_rtc_ops, THIS_MODULE);
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return PTR_ERR_OR_ZERO(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 = 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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