rtc: import ds1307 driver from linux-3.15

Current ds1307 rtc driver supports only ds1307 and ds1338 chips;
it has no nvram support at the moment.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 347 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
new file mode 100644
index 0000000000..725f15ab57
--- /dev/null
+++ b/drivers/rtc/rtc-ds1307.c
@@ -0,0 +1,347 @@
+/*
+ * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
+ *
+ *  This code was ported from linux-3.15 kernel by Antony Pavlov.
+ *
+ *  Copyright (C) 2005 James Chapman (ds1337 core)
+ *  Copyright (C) 2006 David Brownell
+ *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
+ *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
+ *
+ * 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 <common.h>
+#include <init.h>
+#include <driver.h>
+#include <xfuncs.h>
+#include <errno.h>
+#include <i2c/i2c.h>
+#include <rtc.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+/*
+ * We can't determine type by probing, but if we expect pre-Linux code
+ * to have set the chip up as a clock (turning on the oscillator and
+ * setting the date and time), Linux can ignore the non-clock features.
+ * That's a natural job for a factory or repair bench.
+ */
+enum ds_type {
+	ds_1307,
+	ds_1338,
+	last_ds_type /* always last */
+};
+
+/* RTC registers don't differ much, except for the century flag */
+#define DS1307_REG_SECS		0x00	/* 00-59 */
+#	define DS1307_BIT_CH		0x80
+#	define DS1340_BIT_nEOSC		0x80
+#define DS1307_REG_MIN		0x01	/* 00-59 */
+#define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
+#	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
+#	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
+#	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
+#	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
+#define DS1307_REG_WDAY		0x03	/* 01-07 */
+#define DS1307_REG_MDAY		0x04	/* 01-31 */
+#define DS1307_REG_MONTH	0x05	/* 01-12 */
+#	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
+#define DS1307_REG_YEAR		0x06	/* 00-99 */
+
+/*
+ * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
+ * start at 7, and they differ a LOT. Only control and status matter for
+ * basic RTC date and time functionality; be careful using them.
+ */
+#define DS1307_REG_CONTROL	0x07		/* or ds1338 */
+#	define DS1307_BIT_OUT		0x80
+#	define DS1338_BIT_OSF		0x20
+#	define DS1307_BIT_SQWE		0x10
+#	define DS1307_BIT_RS1		0x02
+#	define DS1307_BIT_RS0		0x01
+
+struct ds1307 {
+	struct rtc_device	rtc;
+	u8			offset; /* register's offset */
+	u8			regs[11];
+	enum ds_type		type;
+	unsigned long		flags;
+	struct i2c_client	*client;
+	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
+			       u8 length, u8 *values);
+	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
+				u8 length, const u8 *values);
+};
+
+static struct platform_device_id ds1307_id[] = {
+	{ "ds1307", ds_1307 },
+	{ "ds1338", ds_1338 },
+	{ "pt7c4338", ds_1307 },
+	{ }
+};
+
+/*----------------------------------------------------------------------*/
+
+#define BLOCK_DATA_MAX_TRIES 10
+
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+				       u8 command, u8 length, u8 *values)
+{
+	s32 i, data;
+
+	for (i = 0; i < length; i++) {
+		data = i2c_smbus_read_byte_data(client, command + i);
+		if (data < 0)
+			return data;
+		values[i] = data;
+	}
+	return i;
+}
+
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
+				  u8 length, u8 *values)
+{
+	u8 oldvalues[255];
+	s32 ret;
+	int tries = 0;
+
+	dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
+	ret = ds1307_read_block_data_once(client, command, length, values);
+	if (ret < 0)
+		return ret;
+	do {
+		if (++tries > BLOCK_DATA_MAX_TRIES) {
+			dev_err(&client->dev,
+				"ds1307_read_block_data failed\n");
+			return -EIO;
+		}
+		memcpy(oldvalues, values, length);
+		ret = ds1307_read_block_data_once(client, command, length,
+						  values);
+		if (ret < 0)
+			return ret;
+	} while (memcmp(oldvalues, values, length));
+	return length;
+}
+
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
+				   u8 length, const u8 *values)
+{
+	u8 currvalues[255];
+	int tries = 0;
+
+	dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
+	do {
+		s32 i, ret;
+
+		if (++tries > BLOCK_DATA_MAX_TRIES) {
+			dev_err(&client->dev,
+				"ds1307_write_block_data failed\n");
+			return -EIO;
+		}
+		for (i = 0; i < length; i++) {
+			ret = i2c_smbus_write_byte_data(client, command + i,
+							values[i]);
+			if (ret < 0)
+				return ret;
+		}
+		ret = ds1307_read_block_data_once(client, command, length,
+						  currvalues);
+		if (ret < 0)
+			return ret;
+	} while (memcmp(currvalues, values, length));
+	return length;
+}
+
+static inline struct ds1307 *to_ds1307_priv(struct rtc_device *rtcdev)
+{
+	return container_of(rtcdev, struct ds1307, rtc);
+}
+
+static int ds1307_get_time(struct rtc_device *rtcdev, struct rtc_time *t)
+{
+	struct device_d *dev = rtcdev->dev;
+	struct ds1307 *ds1307 = to_ds1307_priv(rtcdev);
+	int		tmp;
+
+	/* read the RTC date and time registers all at once */
+	tmp = ds1307->read_block_data(ds1307->client,
+		ds1307->offset, 7, ds1307->regs);
+	if (tmp != 7) {
+		dev_err(dev, "%s error %d\n", "read", tmp);
+		return -EIO;
+	}
+
+	dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs);
+
+	t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
+	t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
+	tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
+	t->tm_hour = bcd2bin(tmp);
+	t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
+	t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
+	tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
+	t->tm_mon = bcd2bin(tmp) - 1;
+
+	/* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
+	t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
+
+	dev_dbg(dev, "%s secs=%d, mins=%d, "
+		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+		"read", t->tm_sec, t->tm_min,
+		t->tm_hour, t->tm_mday,
+		t->tm_mon, t->tm_year, t->tm_wday);
+
+	/* initial clock setting can be undefined */
+	return rtc_valid_tm(t);
+}
+
+static int ds1307_set_time(struct rtc_device *rtcdev, struct rtc_time *t)
+{
+	struct device_d *dev = rtcdev->dev;
+	struct ds1307 *ds1307 = to_ds1307_priv(rtcdev);
+	int		result;
+	int		tmp;
+	u8		*buf = ds1307->regs;
+
+	dev_dbg(dev, "%s secs=%d, mins=%d, "
+		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+		"write", t->tm_sec, t->tm_min,
+		t->tm_hour, t->tm_mday,
+		t->tm_mon, t->tm_year, t->tm_wday);
+
+	buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
+	buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
+	buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
+	buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
+	buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
+	buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
+
+	/* assume 20YY not 19YY */
+	tmp = t->tm_year - 100;
+	buf[DS1307_REG_YEAR] = bin2bcd(tmp);
+
+	dev_dbg(dev, "%s: %7ph\n", "write", buf);
+
+	result = ds1307->write_block_data(ds1307->client,
+		ds1307->offset, 7, buf);
+	if (result < 0) {
+		dev_err(dev, "%s error %d\n", "write", result);
+		return result;
+	}
+	return 0;
+}
+
+static const struct rtc_class_ops ds13xx_rtc_ops = {
+	.read_time	= ds1307_get_time,
+	.set_time	= ds1307_set_time,
+};
+
+static int ds1307_probe(struct device_d *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1307		*ds1307;
+	int			err = -ENODEV;
+	int			tmp;
+	unsigned char		*buf;
+	unsigned long driver_data;
+
+	ds1307 = xzalloc(sizeof(struct ds1307));
+
+	err = dev_get_drvdata(dev, &driver_data);
+	if (err)
+		goto exit;
+
+	ds1307->client = client;
+	ds1307->type = driver_data;
+
+	buf = ds1307->regs;
+
+	ds1307->read_block_data = ds1307_read_block_data;
+	ds1307->write_block_data = ds1307_write_block_data;
+
+read_rtc:
+	/* read RTC registers */
+	tmp = ds1307->read_block_data(client, ds1307->offset, 8, buf);
+	if (tmp != 8) {
+		dev_dbg(&client->dev, "read error %d\n", tmp);
+		err = -EIO;
+		goto exit;
+	}
+
+	/*
+	 * minimal sanity checking; some chips (like DS1340) don't
+	 * specify the extra bits as must-be-zero, but there are
+	 * still a few values that are clearly out-of-range.
+	 */
+	tmp = ds1307->regs[DS1307_REG_SECS];
+	switch (ds1307->type) {
+	case ds_1307:
+		/* clock halted?  turn it on, so clock can tick. */
+		if (tmp & DS1307_BIT_CH) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
+			dev_warn(&client->dev, "SET TIME!\n");
+			goto read_rtc;
+		}
+		break;
+	case ds_1338:
+		/* clock halted?  turn it on, so clock can tick. */
+		if (tmp & DS1307_BIT_CH)
+			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
+
+		/* oscillator fault?  clear flag, and warn */
+		if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
+					ds1307->regs[DS1307_REG_CONTROL]
+					& ~DS1338_BIT_OSF);
+			dev_warn(&client->dev, "SET TIME!\n");
+			goto read_rtc;
+		}
+		break;
+	default:
+		break;
+	}
+
+	tmp = ds1307->regs[DS1307_REG_HOUR];
+	switch (ds1307->type) {
+	default:
+		if (!(tmp & DS1307_BIT_12HR))
+			break;
+
+		/*
+		 * Be sure we're in 24 hour mode.  Multi-master systems
+		 * take note...
+		 */
+		tmp = bcd2bin(tmp & 0x1f);
+		if (tmp == 12)
+			tmp = 0;
+		if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
+			tmp += 12;
+		i2c_smbus_write_byte_data(client,
+				ds1307->offset + DS1307_REG_HOUR,
+				bin2bcd(tmp));
+	}
+
+	ds1307->rtc.ops = &ds13xx_rtc_ops;
+	ds1307->rtc.dev = dev;
+
+	err = rtc_register(&ds1307->rtc);
+
+exit:
+	return err;
+}
+
+static struct driver_d ds1307_driver = {
+	.name	= "rtc-ds1307",
+	.probe		= ds1307_probe,
+	.id_table	= ds1307_id,
+};
+
+static int __init ds1307_init(void)
+{
+	return i2c_driver_register(&ds1307_driver);
+}
+device_initcall(ds1307_init);