[PATCH] RTC subsystem: X1205 driver

A port of the existing x1205 driver under the new RTC subsystem.

It is actually under test within the NSLU2 project
(http://www.nslu2-linux.org) and it is working quite well.

It is the first driver under this new subsystem and should be used as a guide
to port other drivers.
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/rtc/Kconfig

@@ -76,4 +76,14 @@ config RTC_INTF_DEV
 comment "RTC drivers"
 	depends on RTC_CLASS
 
+config RTC_DRV_X1205
+	tristate "Xicor/Intersil X1205"
+	depends on RTC_CLASS && I2C
+	help
+	  If you say yes here you get support for the
+	  Xicor/Intersil X1205 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-x1205.
+
 endmenu

drivers/rtc/Makefile

@@ -10,3 +10,6 @@ rtc-core-y			:= class.o interface.o
 obj-$(CONFIG_RTC_INTF_SYSFS)	+= rtc-sysfs.o
 obj-$(CONFIG_RTC_INTF_PROC)	+= rtc-proc.o
 obj-$(CONFIG_RTC_INTF_DEV)	+= rtc-dev.o
+
+obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
+

drivers/rtc/rtc-x1205.c

+/*
+ * An i2c driver for the Xicor/Intersil X1205 RTC
+ * Copyright 2004 Karen Spearel
+ * Copyright 2005 Alessandro Zummo
+ *
+ * please send all reports to:
+ * 	Karen Spearel <kas111 at gmail dot com>
+ *	Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * based on a lot of other RTC drivers.
+ *
+ * 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/delay.h>
+
+#define DRV_VERSION "1.0.6"
+
+/* Addresses to scan: none. This chip is located at
+ * 0x6f and uses a two bytes register addressing.
+ * Two bytes need to be written to read a single register,
+ * while most other chips just require one and take the second
+ * one as the data to be written. To prevent corrupting
+ * unknown chips, the user must explicitely set the probe parameter.
+ */
+
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD;
+
+/* offsets into CCR area */
+
+#define CCR_SEC			0
+#define CCR_MIN			1
+#define CCR_HOUR		2
+#define CCR_MDAY		3
+#define CCR_MONTH		4
+#define CCR_YEAR		5
+#define CCR_WDAY		6
+#define CCR_Y2K			7
+
+#define X1205_REG_SR		0x3F	/* status register */
+#define X1205_REG_Y2K		0x37
+#define X1205_REG_DW		0x36
+#define X1205_REG_YR		0x35
+#define X1205_REG_MO		0x34
+#define X1205_REG_DT		0x33
+#define X1205_REG_HR		0x32
+#define X1205_REG_MN		0x31
+#define X1205_REG_SC		0x30
+#define X1205_REG_DTR		0x13
+#define X1205_REG_ATR		0x12
+#define X1205_REG_INT		0x11
+#define X1205_REG_0		0x10
+#define X1205_REG_Y2K1		0x0F
+#define X1205_REG_DWA1		0x0E
+#define X1205_REG_YRA1		0x0D
+#define X1205_REG_MOA1		0x0C
+#define X1205_REG_DTA1		0x0B
+#define X1205_REG_HRA1		0x0A
+#define X1205_REG_MNA1		0x09
+#define X1205_REG_SCA1		0x08
+#define X1205_REG_Y2K0		0x07
+#define X1205_REG_DWA0		0x06
+#define X1205_REG_YRA0		0x05
+#define X1205_REG_MOA0		0x04
+#define X1205_REG_DTA0		0x03
+#define X1205_REG_HRA0		0x02
+#define X1205_REG_MNA0		0x01
+#define X1205_REG_SCA0		0x00
+
+#define X1205_CCR_BASE		0x30	/* Base address of CCR */
+#define X1205_ALM0_BASE		0x00	/* Base address of ALARM0 */
+
+#define X1205_SR_RTCF		0x01	/* Clock failure */
+#define X1205_SR_WEL		0x02	/* Write Enable Latch */
+#define X1205_SR_RWEL		0x04	/* Register Write Enable */
+
+#define X1205_DTR_DTR0		0x01
+#define X1205_DTR_DTR1		0x02
+#define X1205_DTR_DTR2		0x04
+
+#define X1205_HR_MIL		0x80	/* Set in ccr.hour for 24 hr mode */
+
+/* Prototypes */
+static int x1205_attach(struct i2c_adapter *adapter);
+static int x1205_detach(struct i2c_client *client);
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind);
+
+static struct i2c_driver x1205_driver = {
+	.driver		= {
+		.name	= "x1205",
+	},
+	.id		= I2C_DRIVERID_X1205,
+	.attach_adapter = &x1205_attach,
+	.detach_client	= &x1205_detach,
+};
+
+/*
+ * In the routines that deal directly with the x1205 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
+ * Epoch is initialized as 2000. Time is set to UTC.
+ */
+static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
+				unsigned char reg_base)
+{
+	unsigned char dt_addr[2] = { 0, reg_base };
+
+	unsigned char buf[8];
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, dt_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 8, buf },	/* read date */
+	};
+
+	/* read date registers */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev,
+		"%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
+		"mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",
+		__FUNCTION__,
+		buf[0], buf[1], buf[2], buf[3],
+		buf[4], buf[5], buf[6], buf[7]);
+
+	tm->tm_sec = BCD2BIN(buf[CCR_SEC]);
+	tm->tm_min = BCD2BIN(buf[CCR_MIN]);
+	tm->tm_hour = BCD2BIN(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
+	tm->tm_mday = BCD2BIN(buf[CCR_MDAY]);
+	tm->tm_mon = BCD2BIN(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
+	tm->tm_year = BCD2BIN(buf[CCR_YEAR])
+			+ (BCD2BIN(buf[CCR_Y2K]) * 100) - 1900;
+	tm->tm_wday = buf[CCR_WDAY];
+
+	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__FUNCTION__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	return 0;
+}
+
+static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
+{
+	static unsigned char sr_addr[2] = { 0, X1205_REG_SR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, sr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, sr },	/* read status */
+	};
+
+	/* read status register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
+				int datetoo, u8 reg_base)
+{
+	int i, xfer;
+	unsigned char buf[8];
+
+	static const unsigned char wel[3] = { 0, X1205_REG_SR,
+						X1205_SR_WEL };
+
+	static const unsigned char rwel[3] = { 0, X1205_REG_SR,
+						X1205_SR_WEL | X1205_SR_RWEL };
+
+	static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };
+
+	dev_dbg(&client->dev,
+		"%s: secs=%d, mins=%d, hours=%d\n",
+		__FUNCTION__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour);
+
+	buf[CCR_SEC] = BIN2BCD(tm->tm_sec);
+	buf[CCR_MIN] = BIN2BCD(tm->tm_min);
+
+	/* set hour and 24hr bit */
+	buf[CCR_HOUR] = BIN2BCD(tm->tm_hour) | X1205_HR_MIL;
+
+	/* should we also set the date? */
+	if (datetoo) {
+		dev_dbg(&client->dev,
+			"%s: mday=%d, mon=%d, year=%d, wday=%d\n",
+			__FUNCTION__,
+			tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+		buf[CCR_MDAY] = BIN2BCD(tm->tm_mday);
+
+		/* month, 1 - 12 */
+		buf[CCR_MONTH] = BIN2BCD(tm->tm_mon + 1);
+
+		/* year, since the rtc epoch*/
+		buf[CCR_YEAR] = BIN2BCD(tm->tm_year % 100);
+		buf[CCR_WDAY] = tm->tm_wday & 0x07;
+		buf[CCR_Y2K] = BIN2BCD(tm->tm_year / 100);
+	}
+
+	/* this sequence is required to unlock the chip */
+	if ((xfer = i2c_master_send(client, wel, 3)) != 3) {
+		dev_err(&client->dev, "%s: wel - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	if ((xfer = i2c_master_send(client, rwel, 3)) != 3) {
+		dev_err(&client->dev, "%s: rwel - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	/* write register's data */
+	for (i = 0; i < (datetoo ? 8 : 3); i++) {
+		unsigned char rdata[3] = { 0, reg_base + i, buf[i] };
+
+		xfer = i2c_master_send(client, rdata, 3);
+		if (xfer != 3) {
+			dev_err(&client->dev,
+				"%s: xfer=%d addr=%02x, data=%02x\n",
+				__FUNCTION__,
+				 xfer, rdata[1], rdata[2]);
+			return -EIO;
+		}
+	};
+
+	/* disable further writes */
+	if ((xfer = i2c_master_send(client, diswe, 3)) != 3) {
+		dev_err(&client->dev, "%s: diswe - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int x1205_fix_osc(struct i2c_client *client)
+{
+	int err;
+	struct rtc_time tm;
+
+	tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+
+	if ((err = x1205_set_datetime(client, &tm, 0, X1205_CCR_BASE)) < 0)
+		dev_err(&client->dev,
+			"unable to restart the oscillator\n");
+
+	return err;
+}
+
+static int x1205_get_dtrim(struct i2c_client *client, int *trim)
+{
+	unsigned char dtr;
+	static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, dtr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, &dtr }, 	/* read dtr */
+	};
+
+	/* read dtr register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev, "%s: raw dtr=%x\n", __FUNCTION__, dtr);
+
+	*trim = 0;
+
+	if (dtr & X1205_DTR_DTR0)
+		*trim += 20;
+
+	if (dtr & X1205_DTR_DTR1)
+		*trim += 10;
+
+	if (dtr & X1205_DTR_DTR2)
+		*trim = -*trim;
+
+	return 0;
+}
+
+static int x1205_get_atrim(struct i2c_client *client, int *trim)
+{
+	s8 atr;
+	static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, atr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, &atr }, 	/* read atr */
+	};
+
+	/* read atr register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev, "%s: raw atr=%x\n", __FUNCTION__, atr);
+
+	/* atr is a two's complement value on 6 bits,
+	 * perform sign extension. The formula is
+	 * Catr = (atr * 0.25pF) + 11.00pF.
+	 */
+	if (atr & 0x20)
+		atr |= 0xC0;
+
+	dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __FUNCTION__, atr, atr);
+
+	*trim = (atr * 250) + 11000;
+
+	dev_dbg(&client->dev, "%s: real=%d\n", __FUNCTION__, *trim);
+
+	return 0;
+}
+
+struct x1205_limit
+{
+	unsigned char reg, mask, min, max;
+};
+
+static int x1205_validate_client(struct i2c_client *client)
+{
+	int i, xfer;
+
+	/* Probe array. We will read the register at the specified
+	 * address and check if the given bits are zero.
+	 */
+	static const unsigned char probe_zero_pattern[] = {
+		/* register, mask */
+		X1205_REG_SR,	0x18,
+		X1205_REG_DTR,	0xF8,
+		X1205_REG_ATR,	0xC0,
+		X1205_REG_INT,	0x18,
+		X1205_REG_0,	0xFF,
+	};
+
+	static const struct x1205_limit probe_limits_pattern[] = {
+		/* register, mask, min, max */
+		{ X1205_REG_Y2K,	0xFF,	19,	20	},
+		{ X1205_REG_DW,		0xFF,	0,	6	},
+		{ X1205_REG_YR,		0xFF,	0,	99	},
+		{ X1205_REG_MO,		0xFF,	0,	12	},
+		{ X1205_REG_DT,		0xFF,	0,	31	},
+		{ X1205_REG_HR,		0x7F,	0,	23	},
+		{ X1205_REG_MN,		0xFF,	0,	59	},
+		{ X1205_REG_SC,		0xFF,	0,	59	},
+		{ X1205_REG_Y2K1,	0xFF,	19,	20	},
+		{ X1205_REG_Y2K0,	0xFF,	19,	20	},
+	};
+
+	/* check that registers have bits a 0 where expected */
+	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
+		unsigned char buf;
+
+		unsigned char addr[2] = { 0, probe_zero_pattern[i] };
+
+		struct i2c_msg msgs[2] = {
+			{ client->addr, 0, 2, addr },
+			{ client->addr, I2C_M_RD, 1, &buf },
+		};
+
+		if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
+			dev_err(&client->adapter->dev,
+				"%s: could not read register %x\n",
+				__FUNCTION__, probe_zero_pattern[i]);
+
+			return -EIO;
+		}
+
+		if ((buf & probe_zero_pattern[i+1]) != 0) {
+			dev_err(&client->adapter->dev,
+				"%s: register=%02x, zero pattern=%d, value=%x\n",
+				__FUNCTION__, probe_zero_pattern[i], i, buf);
+
+			return -ENODEV;
+		}
+	}
+
+	/* check limits (only registers with bcd values) */
+	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
+		unsigned char reg, value;
+
+		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };
+
+		struct i2c_msg msgs[2] = {
+			{ client->addr, 0, 2, addr },
+			{ client->addr, I2C_M_RD, 1, &reg },
+		};
+
+		if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
+			dev_err(&client->adapter->dev,
+				"%s: could not read register %x\n",
+				__FUNCTION__, probe_limits_pattern[i].reg);
+
+			return -EIO;
+		}
+
+		value = BCD2BIN(reg & probe_limits_pattern[i].mask);
+
+		if (value > probe_limits_pattern[i].max ||
+			value < probe_limits_pattern[i].min) {
+			dev_dbg(&client->adapter->dev,
+				"%s: register=%x, lim pattern=%d, value=%d\n",
+				__FUNCTION__, probe_limits_pattern[i].reg,
+				i, value);
+
+			return -ENODEV;
+		}
+	}
+
+	return 0;
+}
+
+static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	return x1205_get_datetime(to_i2c_client(dev),
+		&alrm->time, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	return x1205_set_datetime(to_i2c_client(dev),
+		&alrm->time, 1, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return x1205_get_datetime(to_i2c_client(dev),
+		tm, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return x1205_set_datetime(to_i2c_client(dev),
+		tm, 1, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	int err, dtrim, atrim;
+
+	seq_printf(seq, "24hr\t\t: yes\n");
+
+	if ((err = x1205_get_dtrim(to_i2c_client(dev), &dtrim)) == 0)
+		seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);
+
+	if ((err = x1205_get_atrim(to_i2c_client(dev), &atrim)) == 0)
+		seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
+			atrim / 1000, atrim % 1000);
+	return 0;
+}
+
+static struct rtc_class_ops x1205_rtc_ops = {
+	.proc		= x1205_rtc_proc,
+	.read_time	= x1205_rtc_read_time,
+	.set_time	= x1205_rtc_set_time,
+	.read_alarm	= x1205_rtc_read_alarm,
+	.set_alarm	= x1205_rtc_set_alarm,
+};
+
+static ssize_t x1205_sysfs_show_atrim(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int atrim;
+
+	if (x1205_get_atrim(to_i2c_client(dev), &atrim) == 0)
+		return sprintf(buf, "%d.%02d pF\n",
+			atrim / 1000, atrim % 1000);
+	return 0;
+}
+static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);
+
+static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int dtrim;
+
+	if (x1205_get_dtrim(to_i2c_client(dev), &dtrim) == 0)
+		return sprintf(buf, "%d ppm\n", dtrim);
+
+	return 0;
+}
+static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);
+
+static int x1205_attach(struct i2c_adapter *adapter)
+{
+	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+	return i2c_probe(adapter, &addr_data, x1205_probe);
+}
+
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind)
+{
+	int err = 0;
+	unsigned char sr;
+	struct i2c_client *client;
+	struct rtc_device *rtc;
+
+	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
+		err = -ENODEV;
+		goto exit;
+	}
+
+	if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	/* I2C client */
+	client->addr = address;
+	client->driver = &x1205_driver;
+	client->adapter	= adapter;
+
+	strlcpy(client->name, x1205_driver.driver.name, I2C_NAME_SIZE);
+
+	/* Verify the chip is really an X1205 */
+	if (kind < 0) {
+		if (x1205_validate_client(client) < 0) {
+			err = -ENODEV;
+			goto exit_kfree;
+		}
+	}
+
+	/* Inform the i2c layer */
+	if ((err = i2c_attach_client(client)))
+		goto exit_kfree;
+
+	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+	rtc = rtc_device_register(x1205_driver.driver.name, &client->dev,
+				&x1205_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(rtc)) {
+		err = PTR_ERR(rtc);
+		dev_err(&client->dev,
+			"unable to register the class device\n");
+		goto exit_detach;
+	}
+
+	i2c_set_clientdata(client, rtc);
+
+	/* Check for power failures and eventualy enable the osc */
+	if ((err = x1205_get_status(client, &sr)) == 0) {
+		if (sr & X1205_SR_RTCF) {
+			dev_err(&client->dev,
+				"power failure detected, "
+				"please set the clock\n");
+			udelay(50);
+			x1205_fix_osc(client);
+		}
+	}
+	else
+		dev_err(&client->dev, "couldn't read status\n");
+
+	device_create_file(&client->dev, &dev_attr_atrim);
+	device_create_file(&client->dev, &dev_attr_dtrim);
+
+	return 0;
+
+exit_detach:
+	i2c_detach_client(client);
+
+exit_kfree:
+	kfree(client);
+
+exit:
+	return err;
+}
+
+static int x1205_detach(struct i2c_client *client)
+{
+	int err;
+	struct rtc_device *rtc = i2c_get_clientdata(client);
+
+	dev_dbg(&client->dev, "%s\n", __FUNCTION__);
+
+ 	if (rtc)
+		rtc_device_unregister(rtc);
+
+	if ((err = i2c_detach_client(client)))
+		return err;
+
+	kfree(client);
+
+	return 0;
+}
+
+static int __init x1205_init(void)
+{
+	return i2c_add_driver(&x1205_driver);
+}
+
+static void __exit x1205_exit(void)
+{
+	i2c_del_driver(&x1205_driver);
+}
+
+MODULE_AUTHOR(
+	"Karen Spearel <kas111 at gmail dot com>, "
+	"Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(x1205_init);
+module_exit(x1205_exit);