[PATCH] I2C: m41t00: Add support for the ST M41T81 and M41T85

This patch adds support for the ST m41t81 and m41t85 i2c rtc chips
to the existing m41t00 driver.

Since there is no way to reliably determine what type of rtc chip
is in use, the chip type is passed in via platform_data.  The i2c
address and square wave frequency are passed in via platform_data
as well.  To accommodate the use of platform_data, a new header
file include/linux/m41t00.h has been added.

The m41t81 and m41t85 chips halt the updating of their time registers
while they are being accessed.  They resume when a stop condition
exists on the i2c bus or when non-time related regs are accessed.
To make the best use of that facility and to make more efficient
use of the i2c bus, this patch replaces multiple i2c_smbus_xxx calls
with a single i2c_transfer call.

Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 241 insertions, 72 deletions

diff --git a/drivers/i2c/chips/m41t00.c b/drivers/i2c/chips/m41t00.c
index eb2be3e..2dd0a34 100644
--- a/drivers/i2c/chips/m41t00.c
+++ b/drivers/i2c/chips/m41t00.c
@@ -1,9 +1,9 @@
 /*
- * I2C client/driver for the ST M41T00 Real-Time Clock chip.
+ * I2C client/driver for the ST M41T00 family of i2c rtc chips.
  *
  * Author: Mark A. Greer <mgreer@mvista.com>
  *
- * 2005 (c) MontaVista Software, Inc. This file is licensed under
+ * 2005, 2006 (c) MontaVista Software, Inc. This file is licensed under
  * the terms of the GNU General Public License version 2. This program
  * is licensed "as is" without any warranty of any kind, whether express
  * or implied.
@@ -19,21 +19,17 @@
 #include <linux/i2c.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
-#include <linux/mutex.h>
 #include <linux/workqueue.h>
-
+#include <linux/platform_device.h>
+#include <linux/m41t00.h>
 #include <asm/time.h>
 #include <asm/rtc.h>
 
-#define	M41T00_DRV_NAME		"m41t00"
-
-static DEFINE_MUTEX(m41t00_mutex);
-
 static struct i2c_driver m41t00_driver;
 static struct i2c_client *save_client;
 
 static unsigned short ignore[] = { I2C_CLIENT_END };
-static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
+static unsigned short normal_addr[] = { I2C_CLIENT_END, I2C_CLIENT_END };
 
 static struct i2c_client_address_data addr_data = {
 	.normal_i2c	= normal_addr,
@@ -41,34 +37,92 @@ static struct i2c_client_address_data addr_data = {
 	.ignore		= ignore,
 };
 
+struct m41t00_chip_info {
+	u8	type;
+	char	*name;
+	u8	read_limit;
+	u8	sec;		/* Offsets for chip regs */
+	u8	min;
+	u8	hour;
+	u8	day;
+	u8	mon;
+	u8	year;
+	u8	alarm_mon;
+	u8	alarm_hour;
+	u8	sqw;
+	u8	sqw_freq;
+};
+
+static struct m41t00_chip_info m41t00_chip_info_tbl[] = {
+	{
+		.type		= M41T00_TYPE_M41T00,
+		.name		= "m41t00",
+		.read_limit	= 5,
+		.sec		= 0,
+		.min		= 1,
+		.hour		= 2,
+		.day		= 4,
+		.mon		= 5,
+		.year		= 6,
+	},
+	{
+		.type		= M41T00_TYPE_M41T81,
+		.name		= "m41t81",
+		.read_limit	= 1,
+		.sec		= 1,
+		.min		= 2,
+		.hour		= 3,
+		.day		= 5,
+		.mon		= 6,
+		.year		= 7,
+		.alarm_mon	= 0xa,
+		.alarm_hour	= 0xc,
+		.sqw		= 0x13,
+	},
+	{
+		.type		= M41T00_TYPE_M41T85,
+		.name		= "m41t85",
+		.read_limit	= 1,
+		.sec		= 1,
+		.min		= 2,
+		.hour		= 3,
+		.day		= 5,
+		.mon		= 6,
+		.year		= 7,
+		.alarm_mon	= 0xa,
+		.alarm_hour	= 0xc,
+		.sqw		= 0x13,
+	},
+};
+static struct m41t00_chip_info *m41t00_chip;
+
 ulong
 m41t00_get_rtc_time(void)
 {
 	s32 sec, min, hour, day, mon, year;
 	s32 sec1, min1, hour1, day1, mon1, year1;
-	ulong limit = 10;
+	u8 reads = 0;
+	u8 buf[8], msgbuf[1] = { 0 }; /* offset into rtc's regs */
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= save_client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= msgbuf,
+		},
+		{
+			.addr	= save_client->addr,
+			.flags	= I2C_M_RD,
+			.len	= 8,
+			.buf	= buf,
+		},
+	};
 
 	sec = min = hour = day = mon = year = 0;
-	sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
 
-	mutex_lock(&m41t00_mutex);
 	do {
-		if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
-			&& ((min = i2c_smbus_read_byte_data(save_client, 1))
-				>= 0)
-			&& ((hour = i2c_smbus_read_byte_data(save_client, 2))
-				>= 0)
-			&& ((day = i2c_smbus_read_byte_data(save_client, 4))
-				>= 0)
-			&& ((mon = i2c_smbus_read_byte_data(save_client, 5))
-				>= 0)
-			&& ((year = i2c_smbus_read_byte_data(save_client, 6))
-				>= 0)
-			&& ((sec == sec1) && (min == min1) && (hour == hour1)
-				&& (day == day1) && (mon == mon1)
-				&& (year == year1)))
-
-				break;
+		if (i2c_transfer(save_client->adapter, msgs, 2) < 0)
+			goto read_err;
 
 		sec1 = sec;
 		min1 = min;
@@ -76,21 +130,21 @@ m41t00_get_rtc_time(void)
 		day1 = day;
 		mon1 = mon;
 		year1 = year;
-	} while (--limit > 0);
-	mutex_unlock(&m41t00_mutex);
-
-	if (limit == 0) {
-		dev_warn(&save_client->dev,
-			"m41t00: can't read rtc chip\n");
-		sec = min = hour = day = mon = year = 0;
-	}
 
-	sec &= 0x7f;
-	min &= 0x7f;
-	hour &= 0x3f;
-	day &= 0x3f;
-	mon &= 0x1f;
-	year &= 0xff;
+		sec = buf[m41t00_chip->sec] & 0x7f;
+		min = buf[m41t00_chip->min] & 0x7f;
+		hour = buf[m41t00_chip->hour] & 0x3f;
+		day = buf[m41t00_chip->day] & 0x3f;
+		mon = buf[m41t00_chip->mon] & 0x1f;
+		year = buf[m41t00_chip->year];
+	} while ((++reads < m41t00_chip->read_limit) && ((sec != sec1)
+			|| (min != min1) || (hour != hour1) || (day != day1)
+			|| (mon != mon1) || (year != year1)));
+
+	if ((m41t00_chip->read_limit > 1) && ((sec != sec1) || (min != min1)
+			|| (hour != hour1) || (day != day1) || (mon != mon1)
+			|| (year != year1)))
+		goto read_err;
 
 	sec = BCD2BIN(sec);
 	min = BCD2BIN(min);
@@ -104,40 +158,60 @@ m41t00_get_rtc_time(void)
 		year += 100;
 
 	return mktime(year, mon, day, hour, min, sec);
+
+read_err:
+	dev_err(&save_client->dev, "m41t00_get_rtc_time: Read error\n");
+	return 0;
 }
+EXPORT_SYMBOL_GPL(m41t00_get_rtc_time);
 
 static void
 m41t00_set(void *arg)
 {
 	struct rtc_time	tm;
-	ulong nowtime = *(ulong *)arg;
+	int nowtime = *(int *)arg;
+	s32 sec, min, hour, day, mon, year;
+	u8 wbuf[9], *buf = &wbuf[1], msgbuf[1] = { 0 };
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= save_client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= msgbuf,
+		},
+		{
+			.addr	= save_client->addr,
+			.flags	= I2C_M_RD,
+			.len	= 8,
+			.buf	= buf,
+		},
+	};
 
 	to_tm(nowtime, &tm);
 	tm.tm_year = (tm.tm_year - 1900) % 100;
 
-	tm.tm_sec = BIN2BCD(tm.tm_sec);
-	tm.tm_min = BIN2BCD(tm.tm_min);
-	tm.tm_hour = BIN2BCD(tm.tm_hour);
-	tm.tm_mon = BIN2BCD(tm.tm_mon);
-	tm.tm_mday = BIN2BCD(tm.tm_mday);
-	tm.tm_year = BIN2BCD(tm.tm_year);
-
-	mutex_lock(&m41t00_mutex);
-	if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
-		|| (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x3f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x3f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x1f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0xff)
-			< 0))
-
-		dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
-
-	mutex_unlock(&m41t00_mutex);
+	sec = BIN2BCD(tm.tm_sec);
+	min = BIN2BCD(tm.tm_min);
+	hour = BIN2BCD(tm.tm_hour);
+	day = BIN2BCD(tm.tm_mday);
+	mon = BIN2BCD(tm.tm_mon);
+	year = BIN2BCD(tm.tm_year);
+
+	/* Read reg values into buf[0..7]/wbuf[1..8] */
+	if (i2c_transfer(save_client->adapter, msgs, 2) < 0) {
+		dev_err(&save_client->dev, "m41t00_set: Read error\n");
+		return;
+	}
+
+	wbuf[0] = 0; /* offset into rtc's regs */
+	buf[m41t00_chip->sec] = (buf[m41t00_chip->sec] & ~0x7f) | (sec & 0x7f);
+	buf[m41t00_chip->min] = (buf[m41t00_chip->min] & ~0x7f) | (min & 0x7f);
+	buf[m41t00_chip->hour] = (buf[m41t00_chip->hour] & ~0x3f) | (hour& 0x3f);
+	buf[m41t00_chip->day] = (buf[m41t00_chip->day] & ~0x3f) | (day & 0x3f);
+	buf[m41t00_chip->mon] = (buf[m41t00_chip->mon] & ~0x1f) | (mon & 0x1f);
+
+	if (i2c_master_send(save_client, wbuf, 9) < 0)
+		dev_err(&save_client->dev, "m41t00_set: Write error\n");
 }
 
 static ulong new_time;
@@ -156,6 +230,48 @@ m41t00_set_rtc_time(ulong nowtime)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(m41t00_set_rtc_time);
+
+/*
+ *****************************************************************************
+ *
+ *	platform_data Driver Interface
+ *
+ *****************************************************************************
+ */
+static int __init
+m41t00_platform_probe(struct platform_device *pdev)
+{
+	struct m41t00_platform_data *pdata;
+	int i;
+
+	if (pdev && (pdata = pdev->dev.platform_data)) {
+		normal_addr[0] = pdata->i2c_addr;
+
+		for (i=0; i<ARRAY_SIZE(m41t00_chip_info_tbl); i++)
+			if (m41t00_chip_info_tbl[i].type == pdata->type) {
+				m41t00_chip = &m41t00_chip_info_tbl[i];
+				m41t00_chip->sqw_freq = pdata->sqw_freq;
+				return 0;
+			}
+	}
+	return -ENODEV;
+}
+
+static int __exit
+m41t00_platform_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static struct platform_driver m41t00_platform_driver = {
+	.probe  = m41t00_platform_probe,
+	.remove = m41t00_platform_remove,
+	.driver = {
+		.owner = THIS_MODULE,
+		.name  = M41T00_DRV_NAME,
+	},
+};
 
 /*
  *****************************************************************************
@@ -170,23 +286,71 @@ m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
 	struct i2c_client *client;
 	int rc;
 
+	if (!i2c_check_functionality(adap, I2C_FUNC_I2C
+			| I2C_FUNC_SMBUS_BYTE_DATA))
+		return 0;
+
 	client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 	if (!client)
 		return -ENOMEM;
 
-	strlcpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
+	strlcpy(client->name, m41t00_chip->name, I2C_NAME_SIZE);
 	client->addr = addr;
 	client->adapter = adap;
 	client->driver = &m41t00_driver;
 
-	if ((rc = i2c_attach_client(client)) != 0) {
-		kfree(client);
-		return rc;
+	if ((rc = i2c_attach_client(client)))
+		goto attach_err;
+
+	if (m41t00_chip->type != M41T00_TYPE_M41T00) {
+		/* If asked, disable SQW, set SQW frequency & re-enable */
+		if (m41t00_chip->sqw_freq)
+			if (((rc = i2c_smbus_read_byte_data(client,
+					m41t00_chip->alarm_mon)) < 0)
+			 || ((rc = i2c_smbus_write_byte_data(client,
+					m41t00_chip->alarm_mon, rc & ~0x40)) <0)
+			 || ((rc = i2c_smbus_write_byte_data(client,
+					m41t00_chip->sqw,
+					m41t00_chip->sqw_freq)) < 0)
+			 || ((rc = i2c_smbus_write_byte_data(client,
+					m41t00_chip->alarm_mon, rc | 0x40)) <0))
+				goto sqw_err;
+
+		/* Make sure HT (Halt Update) bit is cleared */
+		if ((rc = i2c_smbus_read_byte_data(client,
+				m41t00_chip->alarm_hour)) < 0)
+			goto ht_err;
+
+		if (rc & 0x40)
+			if ((rc = i2c_smbus_write_byte_data(client,
+					m41t00_chip->alarm_hour, rc & ~0x40))<0)
+				goto ht_err;
 	}
 
-	m41t00_wq = create_singlethread_workqueue("m41t00");
+	/* Make sure ST (stop) bit is cleared */
+	if ((rc = i2c_smbus_read_byte_data(client, m41t00_chip->sec)) < 0)
+		goto st_err;
+
+	if (rc & 0x80)
+		if ((rc = i2c_smbus_write_byte_data(client, m41t00_chip->sec,
+				rc & ~0x80)) < 0)
+			goto st_err;
+
+	m41t00_wq = create_singlethread_workqueue(m41t00_chip->name);
 	save_client = client;
 	return 0;
+
+st_err:
+	dev_err(&client->dev, "m41t00_probe: Can't clear ST bit\n");
+	goto attach_err;
+ht_err:
+	dev_err(&client->dev, "m41t00_probe: Can't clear HT bit\n");
+	goto attach_err;
+sqw_err:
+	dev_err(&client->dev, "m41t00_probe: Can't set SQW Frequency\n");
+attach_err:
+	kfree(client);
+	return rc;
 }
 
 static int
@@ -219,13 +383,18 @@ static struct i2c_driver m41t00_driver = {
 static int __init
 m41t00_init(void)
 {
-	return i2c_add_driver(&m41t00_driver);
+	int rc;
+
+	if (!(rc = platform_driver_register(&m41t00_platform_driver)))
+		rc = i2c_add_driver(&m41t00_driver);
+	return rc;
 }
 
 static void __exit
 m41t00_exit(void)
 {
 	i2c_del_driver(&m41t00_driver);
+	platform_driver_unregister(&m41t00_platform_driver);
 }
 
 module_init(m41t00_init);