[PATCH] RTC: Add driver for NXP PCF8523 RTC chip

[Yauhen Kharuzhy]

This driver is based on PCF8563 driver and supports only base functions
now: read/write date & time.

Signed-off-by: Yauhen Kharuzhy <yauhen.kharuzhy@xxxxxxxxxxx>
---
 drivers/rtc/Kconfig       |    9 ++
 drivers/rtc/Makefile      |    1 +
 drivers/rtc/rtc-pcf8523.c |  246 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 256 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-pcf8523.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 5a538fc..ace0259a 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -249,6 +249,15 @@ config RTC_DRV_X1205
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-x1205.
 
+config RTC_DRV_PCF8523
+	tristate "NXP PCF8523"
+	help
+	  If you say yes here you get support for the
+	  NXP PCF8523 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-pcf8523.
+
 config RTC_DRV_PCF8563
 	tristate "Philips PCF8563/Epson RTC8564"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6e69823..7812730 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
 obj-$(CONFIG_RTC_DRV_NUC900)	+= rtc-nuc900.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_PCAP)	+= rtc-pcap.o
+obj-$(CONFIG_RTC_DRV_PCF8523)	+= rtc-pcf8523.o
 obj-$(CONFIG_RTC_DRV_PCF8563)	+= rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_PCF8583)	+= rtc-pcf8583.o
 obj-$(CONFIG_RTC_DRV_PCF2123)	+= rtc-pcf2123.o
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
new file mode 100644
index 0000000..06a6679
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -0,0 +1,246 @@
+/*
+ * An I2C driver for the NXP PCF8523 RTC
+ * Copyright 2011 Promwad Innovation Company
+ *
+ * Author: Yauhen Kharuzhy <yauhen.kharuzhy@xxxxxxxxxxx>
+ *	Promwad Innovation Company, http://promwad.com/
+ *
+ * based on the pcf8563 driver
+ *
+ * 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		"1.0"
+
+#define PCF8523_REG_CTL1	0x00 /* control and status registers */
+#define PCF8523_REG_CTL2	0x01
+#define PCF8523_REG_CTL3	0x02
+
+#define PCF8523_REG_SC		0x03 /* datetime */
+#define PCF8523_REG_MN		0x04
+#define PCF8523_REG_HR		0x05
+#define PCF8523_REG_DM		0x06
+#define PCF8523_REG_DW		0x07
+#define PCF8523_REG_MO		0x08
+#define PCF8523_REG_YR		0x09
+
+#define PCF8523_REG_AMN		0x0A /* alarm */
+#define PCF8523_REG_AHR		0x0B
+#define PCF8523_REG_ADM		0x0C
+#define PCF8523_REG_ADW		0x0D
+
+#define PCF8523_REG_CLKO	0x0F /* clock out */
+#define PCF8523_REG_TMRAC	0x10 /* timer control */
+#define PCF8523_REG_TMRA	0x11 /* timer */
+#define PCF8523_REG_TMRBC	0x12 /* timer control */
+#define PCF8523_REG_TMRB	0x13 /* timer */
+
+#define PCF8523_CTL3_BLF	(1 << 2)
+
+static struct i2c_driver pcf8523_driver;
+
+/*
+ * In the routines that deal directly with the pcf8523 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int pcf8523_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	struct pcf8523 *pcf8523 = i2c_get_clientdata(client);
+	unsigned char buf[14] = { PCF8523_REG_CTL1 };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 1, buf },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 14, buf },	/* read status + date */
+	};
+
+	/* read registers */
+	if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __func__);
+		return -EIO;
+	}
+
+	if (buf[PCF8523_REG_CTL3] & PCF8523_CTL3_BLF)
+		dev_info(&client->dev,
+			"low voltage detected, date/time is not reliable.\n");
+
+	dev_dbg(&client->dev,
+		"%s: raw data is ctl1=%02x, ctl2=%02x, ctl3=%02x, "
+		"sec=%02x, min=%02x, hr=%02x, "
+		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
+		__func__,
+		buf[0], buf[1], buf[2], buf[3],
+		buf[4], buf[5], buf[6], buf[7],
+		buf[8], buf[9]);
+
+
+	tm->tm_sec = bcd2bin(buf[PCF8523_REG_SC] & 0x7F);
+	tm->tm_min = bcd2bin(buf[PCF8523_REG_MN] & 0x7F);
+	tm->tm_hour = bcd2bin(buf[PCF8523_REG_HR] & 0x3F); /* rtc hr 0-23 */
+	tm->tm_mday = bcd2bin(buf[PCF8523_REG_DM] & 0x3F);
+	tm->tm_wday = buf[PCF8523_REG_DW] & 0x07;
+	tm->tm_mon = bcd2bin(buf[PCF8523_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
+	tm->tm_year = bcd2bin(buf[PCF8523_REG_YR]);
+	if (tm->tm_year < 70)
+		tm->tm_year += 100;	/* assume we are in 1970...2069 */
+
+	dev_dbg(&client->dev, "%s: tm is 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/time is not valid.\n");
+
+	return 0;
+}
+
+static int pcf8523_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	struct pcf8523 *pcf8523 = i2c_get_clientdata(client);
+	int i, err;
+	unsigned char buf[10];
+
+	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);
+
+	/* hours, minutes and seconds */
+	buf[PCF8523_REG_SC] = bin2bcd(tm->tm_sec);
+	buf[PCF8523_REG_MN] = bin2bcd(tm->tm_min);
+	buf[PCF8523_REG_HR] = bin2bcd(tm->tm_hour);
+
+	buf[PCF8523_REG_DM] = bin2bcd(tm->tm_mday);
+
+	/* month, 1 - 12 */
+	buf[PCF8523_REG_MO] = bin2bcd(tm->tm_mon + 1);
+
+	/* year and century */
+	buf[PCF8523_REG_YR] = bin2bcd(tm->tm_year % 100);
+
+	buf[PCF8523_REG_DW] = tm->tm_wday & 0x07;
+
+	/* write register's data */
+	for (i = 0; i < 7; i++) {
+		unsigned char data[2] = { PCF8523_REG_SC + i,
+						buf[PCF8523_REG_SC + i] };
+
+		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;
+}
+
+static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return pcf8523_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return pcf8523_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops pcf8523_rtc_ops = {
+	.read_time	= pcf8523_rtc_read_time,
+	.set_time	= pcf8523_rtc_set_time,
+};
+
+static int pcf8523_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	struct pcf8523 *pcf8523;
+
+	int err = 0;
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	pcf8523 = kzalloc(sizeof(struct pcf8523), GFP_KERNEL);
+	if (!pcf8523)
+		return -ENOMEM;
+
+	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+	i2c_set_clientdata(client, pcf8523);
+
+	pcf8523->rtc = rtc_device_register(pcf8523_driver.driver.name,
+				&client->dev, &pcf8523_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(pcf8523->rtc)) {
+		err = PTR_ERR(pcf8523->rtc);
+		goto exit_kfree;
+	}
+
+	return 0;
+
+exit_kfree:
+	kfree(pcf8523);
+
+	return err;
+}
+
+static int pcf8523_remove(struct i2c_client *client)
+{
+	struct pcf8523 *pcf8523 = i2c_get_clientdata(client);
+
+	if (pcf8523->rtc)
+		rtc_device_unregister(pcf8523->rtc);
+
+	kfree(pcf8523);
+
+	return 0;
+}
+
+static const struct i2c_device_id pcf8523_id[] = {
+	{ "pcf8523", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pcf8523_id);
+
+static struct i2c_driver pcf8523_driver = {
+	.driver		= {
+		.name	= "rtc-pcf8523",
+	},
+	.probe		= pcf8523_probe,
+	.remove		= pcf8523_remove,
+	.id_table	= pcf8523_id,
+};
+
+static int __init pcf8523_init(void)
+{
+	return i2c_add_driver(&pcf8523_driver);
+}
+
+static void __exit pcf8523_exit(void)
+{
+	i2c_del_driver(&pcf8523_driver);
+}
+
+MODULE_AUTHOR("Yauhen Kharuzhy <yauhen.kharuzhy@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("NXP PCF8523");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(pcf8523_init);
+module_exit(pcf8523_exit);
-- 
1.7.6.3

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