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// SPDX-License-Identifier: GPL-2.0-only
/*
* An I2C driver for the Intersil ISL 12022
*
* Author: Roman Fietze <roman.fietze@telemotive.de>
*
* Based on the Philips PCF8563 RTC
* by Alessandro Zummo <a.zummo@towertech.it>.
*/
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_device.h>
/* ISL register offsets */
#define ISL12022_REG_SC 0x00
#define ISL12022_REG_MN 0x01
#define ISL12022_REG_HR 0x02
#define ISL12022_REG_DT 0x03
#define ISL12022_REG_MO 0x04
#define ISL12022_REG_YR 0x05
#define ISL12022_REG_DW 0x06
#define ISL12022_REG_SR 0x07
#define ISL12022_REG_INT 0x08
/* ISL register bits */
#define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */
#define ISL12022_SR_LBAT85 (1 << 2)
#define ISL12022_SR_LBAT75 (1 << 1)
#define ISL12022_INT_WRTC (1 << 6)
static struct i2c_driver isl12022_driver;
struct isl12022 {
struct rtc_device *rtc;
bool write_enabled; /* true if write enable is set */
};
static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
uint8_t *data, size_t n)
{
struct i2c_msg msgs[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = data
}, /* setup read ptr */
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = n,
.buf = data
}
};
int ret;
data[0] = reg;
ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
if (ret != ARRAY_SIZE(msgs)) {
dev_err(&client->dev, "%s: read error, ret=%d\n",
__func__, ret);
return -EIO;
}
return 0;
}
static int isl12022_write_reg(struct i2c_client *client,
uint8_t reg, uint8_t val)
{
uint8_t data[2] = { reg, val };
int err;
err = i2c_master_send(client, data, sizeof(data));
if (err != sizeof(data)) {
dev_err(&client->dev,
"%s: err=%d addr=%02x, data=%02x\n",
__func__, err, data[0], data[1]);
return -EIO;
}
return 0;
}
/*
* In the routines that deal directly with the isl12022 hardware, we use
* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
*/
static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
uint8_t buf[ISL12022_REG_INT + 1];
int ret;
ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
if (ret)
return ret;
if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
dev_warn(&client->dev,
"voltage dropped below %u%%, "
"date and time is not reliable.\n",
buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
}
dev_dbg(&client->dev,
"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
"sr=%02x, int=%02x",
__func__,
buf[ISL12022_REG_SC],
buf[ISL12022_REG_MN],
buf[ISL12022_REG_HR],
buf[ISL12022_REG_DT],
buf[ISL12022_REG_MO],
buf[ISL12022_REG_YR],
buf[ISL12022_REG_DW],
buf[ISL12022_REG_SR],
buf[ISL12022_REG_INT]);
tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
return 0;
}
static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
struct isl12022 *isl12022 = i2c_get_clientdata(client);
size_t i;
int ret;
uint8_t buf[ISL12022_REG_DW + 1];
dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
if (!isl12022->write_enabled) {
ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
if (ret)
return ret;
/* Check if WRTC (write rtc enable) is set factory default is
* 0 (not set) */
if (!(buf[0] & ISL12022_INT_WRTC)) {
/* Set the write enable bit. */
ret = isl12022_write_reg(client,
ISL12022_REG_INT,
buf[0] | ISL12022_INT_WRTC);
if (ret)
return ret;
/* Write to any RTC register to start RTC, we use the
* HR register, setting the MIL bit to use the 24 hour
* format. */
ret = isl12022_read_regs(client, ISL12022_REG_HR,
buf, 1);
if (ret)
return ret;
ret = isl12022_write_reg(client,
ISL12022_REG_HR,
buf[0] | ISL12022_HR_MIL);
if (ret)
return ret;
}
isl12022->write_enabled = true;
}
/* hours, minutes and seconds */
buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
/* month, 1 - 12 */
buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
/* year and century */
buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
/* write register's data */
for (i = 0; i < ARRAY_SIZE(buf); i++) {
ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
buf[ISL12022_REG_SC + i]);
if (ret)
return -EIO;
}
return 0;
}
static const struct rtc_class_ops isl12022_rtc_ops = {
.read_time = isl12022_rtc_read_time,
.set_time = isl12022_rtc_set_time,
};
static int isl12022_probe(struct i2c_client *client)
{
struct isl12022 *isl12022;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
GFP_KERNEL);
if (!isl12022)
return -ENOMEM;
i2c_set_clientdata(client, isl12022);
isl12022->rtc = devm_rtc_allocate_device(&client->dev);
if (IS_ERR(isl12022->rtc))
return PTR_ERR(isl12022->rtc);
isl12022->rtc->ops = &isl12022_rtc_ops;
isl12022->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
isl12022->rtc->range_max = RTC_TIMESTAMP_END_2099;
return devm_rtc_register_device(isl12022->rtc);
}
#ifdef CONFIG_OF
static const struct of_device_id isl12022_dt_match[] = {
{ .compatible = "isl,isl12022" }, /* for backward compat., don't use */
{ .compatible = "isil,isl12022" },
{ },
};
MODULE_DEVICE_TABLE(of, isl12022_dt_match);
#endif
static const struct i2c_device_id isl12022_id[] = {
{ "isl12022", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, isl12022_id);
static struct i2c_driver isl12022_driver = {
.driver = {
.name = "rtc-isl12022",
#ifdef CONFIG_OF
.of_match_table = of_match_ptr(isl12022_dt_match),
#endif
},
.probe_new = isl12022_probe,
.id_table = isl12022_id,
};
module_i2c_driver(isl12022_driver);
MODULE_AUTHOR("roman.fietze@telemotive.de");
MODULE_DESCRIPTION("ISL 12022 RTC driver");
MODULE_LICENSE("GPL");
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