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linux-next/drivers/rtc/rtc-isl12022.c
Rasmus Villemoes 8d816c1eaa rtc: isl12022: add support for temperature sensor 
The isl12022 has built-in temperature compensation effective over the
range -40C to +85C. It exposes the average of the last two temperature
measurements as a 10-bit value in half-Kelvins. Make this available
via the hwmon framework.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20221104110225.2219761-1-linux@rasmusvillemoes.dk
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2022-11-15 21:01:51 +01:00

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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>
#include <linux/regmap.h>
#include <linux/hwmon.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
#define ISL12022_REG_BETA 0x0d
#define ISL12022_REG_TEMP_L 0x28
/* 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)
#define ISL12022_BETA_TSE (1 << 7)
static struct i2c_driver isl12022_driver;
struct isl12022 {
struct rtc_device *rtc;
struct regmap *regmap;
};
static umode_t isl12022_hwmon_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
if (type == hwmon_temp && attr == hwmon_temp_input)
return 0444;
return 0;
}
/*
* A user-initiated temperature conversion is not started by this function,
* so the temperature is updated once every ~60 seconds.
*/
static int isl12022_hwmon_read_temp(struct device *dev, long *mC)
{
struct isl12022 *isl12022 = dev_get_drvdata(dev);
struct regmap *regmap = isl12022->regmap;
u8 temp_buf[2];
int temp, ret;
ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L,
temp_buf, sizeof(temp_buf));
if (ret)
return ret;
/*
* Temperature is represented as a 10-bit number, unit half-Kelvins.
*/
temp = (temp_buf[1] << 8) | temp_buf[0];
temp *= 500;
temp -= 273000;
*mC = temp;
return 0;
}
static int isl12022_hwmon_read(struct device *dev,
enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
if (type == hwmon_temp && attr == hwmon_temp_input)
return isl12022_hwmon_read_temp(dev, val);
return -EOPNOTSUPP;
}
static const struct hwmon_channel_info *isl12022_hwmon_info[] = {
HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
NULL
};
static const struct hwmon_ops isl12022_hwmon_ops = {
.is_visible = isl12022_hwmon_is_visible,
.read = isl12022_hwmon_read,
};
static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
.ops = &isl12022_hwmon_ops,
.info = isl12022_hwmon_info,
};
static void isl12022_hwmon_register(struct device *dev)
{
struct isl12022 *isl12022;
struct device *hwmon;
int ret;
if (!IS_REACHABLE(CONFIG_HWMON))
return;
isl12022 = dev_get_drvdata(dev);
ret = regmap_update_bits(isl12022->regmap, ISL12022_REG_BETA,
ISL12022_BETA_TSE, ISL12022_BETA_TSE);
if (ret) {
dev_warn(dev, "unable to enable temperature sensor\n");
return;
}
hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", isl12022,
&isl12022_hwmon_chip_info,
NULL);
if (IS_ERR(hwmon))
dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
}
/*
* 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 isl12022 *isl12022 = dev_get_drvdata(dev);
struct regmap *regmap = isl12022->regmap;
uint8_t buf[ISL12022_REG_INT + 1];
int ret;
ret = regmap_bulk_read(regmap, ISL12022_REG_SC, buf, sizeof(buf));
if (ret)
return ret;
if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
dev_warn(dev,
"voltage dropped below %u%%, "
"date and time is not reliable.\n",
buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
}
dev_dbg(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(dev, "%s: %ptR\n", __func__, tm);
return 0;
}
static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct isl12022 *isl12022 = dev_get_drvdata(dev);
struct regmap *regmap = isl12022->regmap;
int ret;
uint8_t buf[ISL12022_REG_DW + 1];
dev_dbg(dev, "%s: %ptR\n", __func__, tm);
/* Ensure the write enable bit is set. */
ret = regmap_update_bits(regmap, ISL12022_REG_INT,
ISL12022_INT_WRTC, ISL12022_INT_WRTC);
if (ret)
return ret;
/* 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;
return regmap_bulk_write(isl12022->regmap, ISL12022_REG_SC,
buf, sizeof(buf));
}
static const struct rtc_class_ops isl12022_rtc_ops = {
.read_time = isl12022_rtc_read_time,
.set_time = isl12022_rtc_set_time,
};
static const struct regmap_config regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.use_single_write = true,
};
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;
dev_set_drvdata(&client->dev, isl12022);
isl12022->regmap = devm_regmap_init_i2c(client, &regmap_config);
if (IS_ERR(isl12022->regmap)) {
dev_err(&client->dev, "regmap allocation failed\n");
return PTR_ERR(isl12022->regmap);
}
isl12022_hwmon_register(&client->dev);
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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