--- /dev/null
+/*
+ * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
+ *
+ * This work is largely based on Intersil ISL1208 driver developed by
+ * Hebert Valerio Riedel <hvr@gnu.org>.
+ *
+ * Detailed datasheet on which this development is based is available here:
+ *
+ * http://natisbad.org/NAS2/refs/ISL12057.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rtc.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+#define DRV_NAME "rtc-isl12057"
+
+/* RTC section */
+#define ISL12057_REG_RTC_SC 0x00 /* Seconds */
+#define ISL12057_REG_RTC_MN 0x01 /* Minutes */
+#define ISL12057_REG_RTC_HR 0x02 /* Hours */
+#define ISL12057_REG_RTC_HR_PM BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
+#define ISL12057_REG_RTC_DW 0x03 /* Day of the Week */
+#define ISL12057_REG_RTC_DT 0x04 /* Date */
+#define ISL12057_REG_RTC_MO 0x05 /* Month */
+#define ISL12057_REG_RTC_YR 0x06 /* Year */
+#define ISL12057_RTC_SEC_LEN 7
+
+/* Alarm 1 section */
+#define ISL12057_REG_A1_SC 0x07 /* Alarm 1 Seconds */
+#define ISL12057_REG_A1_MN 0x08 /* Alarm 1 Minutes */
+#define ISL12057_REG_A1_HR 0x09 /* Alarm 1 Hours */
+#define ISL12057_REG_A1_HR_PM BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_A1_HR_MIL BIT(6) /* 24h/12h format */
+#define ISL12057_REG_A1_DWDT 0x0A /* Alarm 1 Date / Day of the week */
+#define ISL12057_REG_A1_DWDT_B BIT(6) /* DW / DT selection bit */
+#define ISL12057_A1_SEC_LEN 4
+
+/* Alarm 2 section */
+#define ISL12057_REG_A2_MN 0x0B /* Alarm 2 Minutes */
+#define ISL12057_REG_A2_HR 0x0C /* Alarm 2 Hours */
+#define ISL12057_REG_A2_DWDT 0x0D /* Alarm 2 Date / Day of the week */
+#define ISL12057_A2_SEC_LEN 3
+
+/* Control/Status registers */
+#define ISL12057_REG_INT 0x0E
+#define ISL12057_REG_INT_A1IE BIT(0) /* Alarm 1 interrupt enable bit */
+#define ISL12057_REG_INT_A2IE BIT(1) /* Alarm 2 interrupt enable bit */
+#define ISL12057_REG_INT_INTCN BIT(2) /* Interrupt control enable bit */
+#define ISL12057_REG_INT_RS1 BIT(3) /* Freq out control bit 1 */
+#define ISL12057_REG_INT_RS2 BIT(4) /* Freq out control bit 2 */
+#define ISL12057_REG_INT_EOSC BIT(7) /* Oscillator enable bit */
+
+#define ISL12057_REG_SR 0x0F
+#define ISL12057_REG_SR_A1F BIT(0) /* Alarm 1 interrupt bit */
+#define ISL12057_REG_SR_A2F BIT(1) /* Alarm 2 interrupt bit */
+#define ISL12057_REG_SR_OSF BIT(7) /* Oscillator failure bit */
+
+/* Register memory map length */
+#define ISL12057_MEM_MAP_LEN 0x10
+
+struct isl12057_rtc_data {
+ struct regmap *regmap;
+ struct mutex lock;
+};
+
+static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
+{
+ tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
+ tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
+
+ if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
+ tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
+ if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
+ tm->tm_hour += 12;
+ } else { /* 24 hour mode */
+ tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
+ }
+
+ tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
+ tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
+ tm->tm_mon = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
+ tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
+}
+
+static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
+{
+ /*
+ * The clock has an 8 bit wide bcd-coded register for the year.
+ * tm_year is an offset from 1900 and we are interested in the
+ * 2000-2099 range, so any value less than 100 is invalid.
+ */
+ if (tm->tm_year < 100)
+ return -EINVAL;
+
+ regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
+ regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
+ regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
+ regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
+ regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
+ regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
+ regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
+
+ return 0;
+}
+
+/*
+ * Try and match register bits w/ fixed null values to see whether we
+ * are dealing with an ISL12057. Note: this function is called early
+ * during init and hence does need mutex protection.
+ */
+static int isl12057_i2c_validate_chip(struct regmap *regmap)
+{
+ u8 regs[ISL12057_MEM_MAP_LEN];
+ static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
+ 0xc0, 0x60, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x60, 0x7c };
+ int ret, i;
+
+ ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
+ if (regs[i] & mask[i]) /* check if bits are cleared */
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+ u8 regs[ISL12057_RTC_SEC_LEN];
+ int ret;
+
+ mutex_lock(&data->lock);
+ ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
+ ISL12057_RTC_SEC_LEN);
+ mutex_unlock(&data->lock);
+
+ if (ret) {
+ dev_err(dev, "%s: RTC read failed\n", __func__);
+ return ret;
+ }
+
+ isl12057_rtc_regs_to_tm(tm, regs);
+
+ return rtc_valid_tm(tm);
+}
+
+static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+ u8 regs[ISL12057_RTC_SEC_LEN];
+ int ret;
+
+ ret = isl12057_rtc_tm_to_regs(regs, tm);
+ if (ret)
+ return ret;
+
+ mutex_lock(&data->lock);
+ ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
+ ISL12057_RTC_SEC_LEN);
+ mutex_unlock(&data->lock);
+
+ if (ret)
+ dev_err(dev, "%s: RTC write failed\n", __func__);
+
+ return ret;
+}
+
+/*
+ * Check current RTC status and enable/disable what needs to be. Return 0 if
+ * everything went ok and a negative value upon error. Note: this function
+ * is called early during init and hence does need mutex protection.
+ */
+static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
+{
+ int ret;
+
+ /* Enable oscillator if not already running */
+ ret = regmap_update_bits(regmap, ISL12057_REG_INT,
+ ISL12057_REG_INT_EOSC, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to enable oscillator\n");
+ return ret;
+ }
+
+ /* Clear oscillator failure bit if needed */
+ ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+ ISL12057_REG_SR_OSF, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to clear oscillator failure bit\n");
+ return ret;
+ }
+
+ /* Clear alarm bit if needed */
+ ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+ ISL12057_REG_SR_A1F, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to clear alarm bit\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct rtc_class_ops rtc_ops = {
+ .read_time = isl12057_rtc_read_time,
+ .set_time = isl12057_rtc_set_time,
+};
+
+static struct regmap_config isl12057_rtc_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+};
+
+static int isl12057_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct isl12057_rtc_data *data;
+ struct rtc_device *rtc;
+ struct regmap *regmap;
+ int ret;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+ I2C_FUNC_SMBUS_BYTE_DATA |
+ I2C_FUNC_SMBUS_I2C_BLOCK))
+ return -ENODEV;
+
+ regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
+ if (IS_ERR(regmap)) {
+ ret = PTR_ERR(regmap);
+ dev_err(dev, "regmap allocation failed: %d\n", ret);
+ return ret;
+ }
+
+ ret = isl12057_i2c_validate_chip(regmap);
+ if (ret)
+ return ret;
+
+ ret = isl12057_check_rtc_status(dev, regmap);
+ if (ret)
+ return ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ mutex_init(&data->lock);
+ data->regmap = regmap;
+ dev_set_drvdata(dev, data);
+
+ rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id isl12057_dt_match[] = {
+ { .compatible = "isl,isl12057" },
+ { },
+};
+#endif
+
+static const struct i2c_device_id isl12057_id[] = {
+ { "isl12057", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, isl12057_id);
+
+static struct i2c_driver isl12057_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(isl12057_dt_match),
+ },
+ .probe = isl12057_probe,
+ .id_table = isl12057_id,
+};
+module_i2c_driver(isl12057_driver);
+
+MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
+MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
+MODULE_LICENSE("GPL");
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