// 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)) { dev_info(&client->dev, "init write enable and 24 hour format\n"); /* 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, const struct i2c_device_id *id) { 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_device_register(&client->dev, isl12022_driver.driver.name, &isl12022_rtc_ops, THIS_MODULE); return PTR_ERR_OR_ZERO(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 = 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");