1 files changed, 310 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-isl12057.c b/drivers/rtc/rtc-isl12057.c
new file mode 100644
index 000000000000..7854a656628f
--- /dev/null
+++ b/drivers/rtc/rtc-isl12057.c
@@ -0,0 +1,310 @@
+/*
+ * 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");