--- /dev/null
+// 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,
+
+ /* 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),
+};
+
+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, ®val);
+ 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_warn(data->dev,
+ "Crystal oscillation stopped, time is not reliable\n");
+ return -EINVAL;
+ }
+
+ if (FIELD_GET(RX8111_FLAG_VLF_BIT, regval)) {
+ dev_warn(data->dev,
+ "Low voltage detected, time is not reliable\n");
+ return -EINVAL;
+ }
+
+ ret = regmap_field_read(data->regfields[RX8111_REGF_STOP], ®val);
+ if (ret) {
+ dev_dbg(data->dev, "Could not read clock status (%d)\n", ret);
+ return ret;
+ }
+
+ if (regval) {
+ dev_warn(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, ®val);
+ if (ret)
+ return ret;
+
+ vlval = regval ? RTC_VL_DATA_INVALID : 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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