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linux/drivers/rtc/rtc-rx8111.c
Alexandre Belloni eca1b3c2e7 rtc: rx8111: handle VLOW flag 
Allow userspace to get battery status information and be able to warn when
battery is low and has to be replaced.

Tested-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://lore.kernel.org/r/20240417191937.33790-2-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2024-05-07 23:40:10 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for Epson RX8111 RTC.
*
* Copyright (C) 2023 Axis Communications AB
*/
#include <linux/bcd.h>
#include <linux/bitfield.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#define RX8111_REG_SEC 0x10 /* Second counter. */
#define RX8111_REG_MIN 0x11 /* Minute counter */
#define RX8111_REG_HOUR 0x12 /* Hour counter. */
#define RX8111_REG_WEEK 0x13 /* Week day counter. */
#define RX8111_REG_DAY 0x14 /* Month day counter. */
#define RX8111_REG_MONTH 0x15 /* Month counter. */
#define RX8111_REG_YEAR 0x16 /* Year counter. */
#define RX8111_REG_ALARM_MIN 0x17 /* Alarm minute. */
#define RX8111_REG_ALARM_HOUR 0x18 /* Alarm hour. */
#define RX8111_REG_ALARM_WEEK_DAY 0x19 /* Alarm week or month day. */
#define RX8111_REG_TIMER_COUNTER0 0x1a /* Timer counter LSB. */
#define RX8111_REG_TIMER_COUNTER1 0x1b /* Timer counter. */
#define RX8111_REG_TIMER_COUNTER2 0x1c /* Timer counter MSB. */
#define RX8111_REG_EXT 0x1d /* Extension register. */
#define RX8111_REG_FLAG 0x1e /* Flag register. */
#define RX8111_REG_CTRL 0x1f /* Control register. */
#define RX8111_REG_TS_1_1000_SEC 0x20 /* Timestamp 256 or 512 Hz . */
#define RX8111_REG_TS_1_100_SEC 0x21 /* Timestamp 1 - 128 Hz. */
#define RX8111_REG_TS_SEC 0x22 /* Timestamp second. */
#define RX8111_REG_TS_MIN 0x23 /* Timestamp minute. */
#define RX8111_REG_TS_HOUR 0x24 /* Timestamp hour. */
#define RX8111_REG_TS_WEEK 0x25 /* Timestamp week day. */
#define RX8111_REG_TS_DAY 0x26 /* Timestamp month day. */
#define RX8111_REG_TS_MONTH 0x27 /* Timestamp month. */
#define RX8111_REG_TS_YEAR 0x28 /* Timestamp year. */
#define RX8111_REG_TS_STATUS 0x29 /* Timestamp status. */
#define RX8111_REG_EVIN_SETTING 0x2b /* Timestamp trigger setting. */
#define RX8111_REG_ALARM_SEC 0x2c /* Alarm second. */
#define RX8111_REG_TIMER_CTRL 0x2d /* Timer control. */
#define RX8111_REG_TS_CTRL0 0x2e /* Timestamp control 0. */
#define RX8111_REG_CMD_TRIGGER 0x2f /* Timestamp trigger. */
#define RX8111_REG_PWR_SWITCH_CTRL 0x32 /* Power switch control. */
#define RX8111_REG_STATUS_MON 0x33 /* Status monitor. */
#define RX8111_REG_TS_CTRL1 0x34 /* Timestamp control 1. */
#define RX8111_REG_TS_CTRL2 0x35 /* Timestamp control 2. */
#define RX8111_REG_TS_CTRL3 0x36 /* Timestamp control 3. */
#define RX8111_FLAG_XST_BIT BIT(0)
#define RX8111_FLAG_VLF_BIT BIT(1)
#define RX8111_TIME_BUF_SZ (RX8111_REG_YEAR - RX8111_REG_SEC + 1)
enum rx8111_regfield {
/* RX8111_REG_EXT. */
RX8111_REGF_TSEL0,
RX8111_REGF_TSEL1,
RX8111_REGF_ETS,
RX8111_REGF_WADA,
RX8111_REGF_TE,
RX8111_REGF_USEL,
RX8111_REGF_FSEL0,
RX8111_REGF_FSEL1,
/* RX8111_REG_FLAG. */
RX8111_REGF_XST,
RX8111_REGF_VLF,
RX8111_REGF_EVF,
RX8111_REGF_AF,
RX8111_REGF_TF,
RX8111_REGF_UF,
RX8111_REGF_POR,
/* RX8111_REG_CTRL. */
RX8111_REGF_STOP,
RX8111_REGF_EIE,
RX8111_REGF_AIE,
RX8111_REGF_TIE,
RX8111_REGF_UIE,
/* RX8111_REG_PWR_SWITCH_CTRL. */
RX8111_REGF_SMPT0,
RX8111_REGF_SMPT1,
RX8111_REGF_SWSEL0,
RX8111_REGF_SWSEL1,
RX8111_REGF_INIEN,
RX8111_REGF_CHGEN,
/* RX8111_REG_STATUS_MON. */
RX8111_REGF_VLOW,
/* Sentinel value. */
RX8111_REGF_MAX
};
static const struct reg_field rx8111_regfields[] = {
[RX8111_REGF_TSEL0] = REG_FIELD(RX8111_REG_EXT, 0, 0),
[RX8111_REGF_TSEL1] = REG_FIELD(RX8111_REG_EXT, 1, 1),
[RX8111_REGF_ETS] = REG_FIELD(RX8111_REG_EXT, 2, 2),
[RX8111_REGF_WADA] = REG_FIELD(RX8111_REG_EXT, 3, 3),
[RX8111_REGF_TE] = REG_FIELD(RX8111_REG_EXT, 4, 4),
[RX8111_REGF_USEL] = REG_FIELD(RX8111_REG_EXT, 5, 5),
[RX8111_REGF_FSEL0] = REG_FIELD(RX8111_REG_EXT, 6, 6),
[RX8111_REGF_FSEL1] = REG_FIELD(RX8111_REG_EXT, 7, 7),
[RX8111_REGF_XST] = REG_FIELD(RX8111_REG_FLAG, 0, 0),
[RX8111_REGF_VLF] = REG_FIELD(RX8111_REG_FLAG, 1, 1),
[RX8111_REGF_EVF] = REG_FIELD(RX8111_REG_FLAG, 2, 2),
[RX8111_REGF_AF] = REG_FIELD(RX8111_REG_FLAG, 3, 3),
[RX8111_REGF_TF] = REG_FIELD(RX8111_REG_FLAG, 4, 4),
[RX8111_REGF_UF] = REG_FIELD(RX8111_REG_FLAG, 5, 5),
[RX8111_REGF_POR] = REG_FIELD(RX8111_REG_FLAG, 7, 7),
[RX8111_REGF_STOP] = REG_FIELD(RX8111_REG_CTRL, 0, 0),
[RX8111_REGF_EIE] = REG_FIELD(RX8111_REG_CTRL, 2, 2),
[RX8111_REGF_AIE] = REG_FIELD(RX8111_REG_CTRL, 3, 3),
[RX8111_REGF_TIE] = REG_FIELD(RX8111_REG_CTRL, 4, 4),
[RX8111_REGF_UIE] = REG_FIELD(RX8111_REG_CTRL, 5, 5),
[RX8111_REGF_SMPT0] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 0, 0),
[RX8111_REGF_SMPT1] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 1, 1),
[RX8111_REGF_SWSEL0] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 2, 2),
[RX8111_REGF_SWSEL1] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 3, 3),
[RX8111_REGF_INIEN] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 6, 6),
[RX8111_REGF_CHGEN] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 7, 7),
[RX8111_REGF_VLOW] = REG_FIELD(RX8111_REG_STATUS_MON, 1, 1),
};
static const struct regmap_config rx8111_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = RX8111_REG_TS_CTRL3,
};
struct rx8111_data {
struct regmap *regmap;
struct regmap_field *regfields[RX8111_REGF_MAX];
struct device *dev;
struct rtc_device *rtc;
};
static int rx8111_read_vl_flag(struct rx8111_data *data, unsigned int *vlval)
{
int ret;
ret = regmap_field_read(data->regfields[RX8111_REGF_VLF], vlval);
if (ret)
dev_dbg(data->dev, "Could not read VL flag (%d)", ret);
return ret;
}
static int rx8111_read_time(struct device *dev, struct rtc_time *tm)
{
struct rx8111_data *data = dev_get_drvdata(dev);
u8 buf[RX8111_TIME_BUF_SZ];
unsigned int regval;
int ret;
/* Check status. */
ret = regmap_read(data->regmap, RX8111_REG_FLAG, &regval);
if (ret) {
dev_dbg(data->dev, "Could not read flag register (%d)\n", ret);
return ret;
}
if (FIELD_GET(RX8111_FLAG_XST_BIT, regval)) {
dev_dbg(data->dev,
"Crystal oscillation stopped, time is not reliable\n");
return -EINVAL;
}
if (FIELD_GET(RX8111_FLAG_VLF_BIT, regval)) {
dev_dbg(data->dev,
"Low voltage detected, time is not reliable\n");
return -EINVAL;
}
ret = regmap_field_read(data->regfields[RX8111_REGF_STOP], &regval);
if (ret) {
dev_dbg(data->dev, "Could not read clock status (%d)\n", ret);
return ret;
}
if (regval) {
dev_dbg(data->dev, "Clock stopped, time is not reliable\n");
return -EINVAL;
}
/* Read time. */
ret = regmap_bulk_read(data->regmap, RX8111_REG_SEC, buf,
ARRAY_SIZE(buf));
if (ret) {
dev_dbg(data->dev, "Could not bulk read time (%d)\n", ret);
return ret;
}
tm->tm_sec = bcd2bin(buf[0]);
tm->tm_min = bcd2bin(buf[1]);
tm->tm_hour = bcd2bin(buf[2]);
tm->tm_wday = ffs(buf[3]) - 1;
tm->tm_mday = bcd2bin(buf[4]);
tm->tm_mon = bcd2bin(buf[5]) - 1;
tm->tm_year = bcd2bin(buf[6]) + 100;
return 0;
}
static int rx8111_set_time(struct device *dev, struct rtc_time *tm)
{
struct rx8111_data *data = dev_get_drvdata(dev);
u8 buf[RX8111_TIME_BUF_SZ];
int ret;
buf[0] = bin2bcd(tm->tm_sec);
buf[1] = bin2bcd(tm->tm_min);
buf[2] = bin2bcd(tm->tm_hour);
buf[3] = BIT(tm->tm_wday);
buf[4] = bin2bcd(tm->tm_mday);
buf[5] = bin2bcd(tm->tm_mon + 1);
buf[6] = bin2bcd(tm->tm_year - 100);
ret = regmap_clear_bits(data->regmap, RX8111_REG_FLAG,
RX8111_FLAG_XST_BIT | RX8111_FLAG_VLF_BIT);
if (ret)
return ret;
/* Stop the clock. */
ret = regmap_field_write(data->regfields[RX8111_REGF_STOP], 1);
if (ret) {
dev_dbg(data->dev, "Could not stop the clock (%d)\n", ret);
return ret;
}
/* Set the time. */
ret = regmap_bulk_write(data->regmap, RX8111_REG_SEC, buf,
ARRAY_SIZE(buf));
if (ret) {
dev_dbg(data->dev, "Could not bulk write time (%d)\n", ret);
/*
* We don't bother with trying to start the clock again. We
* check for this in rx8111_read_time() (and thus force user to
* call rx8111_set_time() to try again).
*/
return ret;
}
/* Start the clock. */
ret = regmap_field_write(data->regfields[RX8111_REGF_STOP], 0);
if (ret) {
dev_dbg(data->dev, "Could not start the clock (%d)\n", ret);
return ret;
}
return 0;
}
static int rx8111_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct rx8111_data *data = dev_get_drvdata(dev);
unsigned int regval;
unsigned int vlval;
int ret;
switch (cmd) {
case RTC_VL_READ:
ret = rx8111_read_vl_flag(data, &regval);
if (ret)
return ret;
vlval = regval ? RTC_VL_DATA_INVALID : 0;
ret = regmap_field_read(data->regfields[RX8111_REGF_VLOW],
&regval);
if (ret)
return ret;
vlval |= regval ? RTC_VL_BACKUP_LOW : 0;
return put_user(vlval, (typeof(vlval) __user *)arg);
default:
return -ENOIOCTLCMD;
}
}
static const struct rtc_class_ops rx8111_rtc_ops = {
.read_time = rx8111_read_time,
.set_time = rx8111_set_time,
.ioctl = rx8111_ioctl,
};
static int rx8111_probe(struct i2c_client *client)
{
struct rx8111_data *data;
struct rtc_device *rtc;
size_t i;
data = devm_kmalloc(&client->dev, sizeof(*data), GFP_KERNEL);
if (!data) {
dev_dbg(&client->dev, "Could not allocate device data\n");
return -ENOMEM;
}
data->dev = &client->dev;
dev_set_drvdata(data->dev, data);
data->regmap = devm_regmap_init_i2c(client, &rx8111_regmap_config);
if (IS_ERR(data->regmap)) {
dev_dbg(data->dev, "Could not initialize regmap\n");
return PTR_ERR(data->regmap);
}
for (i = 0; i < RX8111_REGF_MAX; ++i) {
data->regfields[i] = devm_regmap_field_alloc(
data->dev, data->regmap, rx8111_regfields[i]);
if (IS_ERR(data->regfields[i])) {
dev_dbg(data->dev,
"Could not allocate register field %zu\n", i);
return PTR_ERR(data->regfields[i]);
}
}
rtc = devm_rtc_allocate_device(data->dev);
if (IS_ERR(rtc)) {
dev_dbg(data->dev, "Could not allocate rtc device\n");
return PTR_ERR(rtc);
}
rtc->ops = &rx8111_rtc_ops;
rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
rtc->range_max = RTC_TIMESTAMP_END_2099;
clear_bit(RTC_FEATURE_ALARM, rtc->features);
return devm_rtc_register_device(rtc);
}
static const struct of_device_id rx8111_of_match[] = {
{
.compatible = "epson,rx8111",
},
{}
};
MODULE_DEVICE_TABLE(of, rx8111_of_match);
static struct i2c_driver rx8111_driver = {
.driver = {
.name = "rtc-rx8111",
.of_match_table = rx8111_of_match,
},
.probe = rx8111_probe,
};
module_i2c_driver(rx8111_driver);
MODULE_AUTHOR("Waqar Hameed <waqar.hameed@axis.com>");
MODULE_DESCRIPTION("Epson RX8111 RTC driver");
MODULE_LICENSE("GPL");
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