rtc: add Intersil ISL12022 RTC driver

- derived from rtc-pcf8563

- no SRAM driver

Signed-off-by: Roman Fietze <roman.fietze@telemotive.de>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 337 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6ed5e7e7e79f..999db51e6a58 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -203,6 +203,15 @@ config RTC_DRV_ISL1208
           This driver can also be built as a module. If so, the module
           will be called rtc-isl1208.
 
+config RTC_DRV_ISL12022
+        tristate "Intersil ISL12022"
+        help
+          If you say yes here you get support for the
+          Intersil ISL12022 RTC chip.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-isl12022.
+
 config RTC_DRV_X1205
         tristate "Xicor/Intersil X1205"
         help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f58129906e1d..e29b7f9377df 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_GENERIC)   += rtc-generic.o
 obj-$(CONFIG_RTC_DRV_IMXDI)     += rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL1208)   += rtc-isl1208.o
+obj-$(CONFIG_RTC_DRV_ISL12022)  += rtc-isl12022.o
 obj-$(CONFIG_RTC_DRV_JZ4740)    += rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_M41T80)    += rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)    += rtc-m41t94.o
diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
new file mode 100644
index 000000000000..4a8c9dd12a7f
--- /dev/null
+++ b/drivers/rtc/rtc-isl12022.c
@@ -0,0 +1,327 @@
+/*
+ * 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>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+#define DRV_VERSION "0.1"
+
+/* 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_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        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);
+
+        /* The clock can give out invalid datetime, but we cannot return
+         * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
+        if (rtc_valid_tm(tm) < 0)
+                dev_err(&client->dev, "retrieved date and time is invalid.\n");
+
+        return 0;
+}
+
+static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        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 = 1;
+        }
+
+        /* 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);
+
+        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 int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        return isl12022_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        return isl12022_set_datetime(to_i2c_client(dev), tm);
+}
+
+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;
+
+        int ret = 0;
+
+        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+                return -ENODEV;
+
+        isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
+        if (!isl12022)
+                return -ENOMEM;
+
+        dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+        i2c_set_clientdata(client, isl12022);
+
+        isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
+                                            &client->dev,
+                                            &isl12022_rtc_ops,
+                                            THIS_MODULE);
+
+        if (IS_ERR(isl12022->rtc)) {
+                ret = PTR_ERR(isl12022->rtc);
+                goto exit_kfree;
+        }
+
+        return 0;
+
+exit_kfree:
+        kfree(isl12022);
+
+        return ret;
+}
+
+static int isl12022_remove(struct i2c_client *client)
+{
+        struct isl12022 *isl12022 = i2c_get_clientdata(client);
+
+        rtc_device_unregister(isl12022->rtc);
+        kfree(isl12022);
+
+        return 0;
+}
+
+static const struct i2c_device_id isl12022_id[] = {
+        { "isl12022", 0 },
+        { "rtc8564", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, isl12022_id);
+
+static struct i2c_driver isl12022_driver = {
+        .driver         = {
+                .name   = "rtc-isl12022",
+        },
+        .probe          = isl12022_probe,
+        .remove         = isl12022_remove,
+        .id_table       = isl12022_id,
+};
+
+static int __init isl12022_init(void)
+{
+        return i2c_add_driver(&isl12022_driver);
+}
+
+static void __exit isl12022_exit(void)
+{
+        i2c_del_driver(&isl12022_driver);
+}
+
+module_init(isl12022_init);
+module_exit(isl12022_exit);
+
+MODULE_AUTHOR("roman.fietze@telemotive.de");
+MODULE_DESCRIPTION("ISL 12022 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);