[PATCH 2.6.16-mm1 3/3] rtc: add support for m41t81 & m41t85 chips to m41t00 driver

[Mark A. Greer]

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@xxxxxxxxxx>
---

 drivers/i2c/chips/m41t00.c |  262 +++++++++++++++++++++++++++++++++------------
 include/linux/m41t00.h     |   50 ++++++++
 2 files changed, 246 insertions(+), 66 deletions(-)
---

diff -Nurp linux-2.6.16-mm1-cleanup/drivers/i2c/chips/m41t00.c linux-2.6.16-mm1-newsupp/drivers/i2c/chips/m41t00.c
--- linux-2.6.16-mm1-cleanup/drivers/i2c/chips/m41t00.c	2006-03-23 16:16:35.000000000 -0700
+++ linux-2.6.16-mm1-newsupp/drivers/i2c/chips/m41t00.c	2006-03-23 18:01:26.000000000 -0700
@@ -1,5 +1,5 @@
 /*
- * 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@xxxxxxxxxx>
  *
@@ -19,22 +19,20 @@
 #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 work_struct set_rtc_time_task;
 
 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[] = { 0, I2C_CLIENT_END };
 
 static struct i2c_client_address_data addr_data = {
 	.normal_i2c	= normal_addr,
@@ -42,34 +40,45 @@ static struct i2c_client_address_data ad
 	.ignore		= ignore,
 };
 
+struct m41t00_chip_info {
+	u16	type;
+	u16	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;
+	u32	sqw_freq;
+};
+
+static struct m41t00_chip_info m41t00_chip_info_tbl[] = {
+	{ M41T00_TYPE_M41T00, 5, 0, 1, 2, 4, 5, 6, 0, 0, 0, 0 },
+	{ M41T00_TYPE_M41T81, 1, 1, 2, 3, 5, 6, 7, 0xa, 0xc, 0x13, 0 },
+	{ M41T00_TYPE_M41T85, 1, 1, 2, 3, 5, 6, 7, 0xa, 0xc, 0x13, 0 },
+};
+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;
+	u16 reads = 0;
+	u8 buf[8], msgbuf[1] = { 0 }; /* offset into rtc's regs */
+	struct i2c_msg msgs[] = {
+		{ save_client->addr, 0, 1, msgbuf },
+		{ save_client->addr, I2C_M_RD, 8, 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;
@@ -77,21 +86,21 @@ 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] & 0xff;
+	} 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);
@@ -105,40 +114,49 @@ 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;
 }
 
 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[] = {
+		{ save_client->addr, 0, 1, msgbuf },
+		{ save_client->addr, I2C_M_RD, 8, 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 & 0x7f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
-			< 0)
-		|| (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
-			< 0))
+	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;
+	}
 
-		dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
+	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);
 
-	mutex_unlock(&m41t00_mutex);
+	if (i2c_master_send(save_client, wbuf, 9) < 0)
+		dev_err(&save_client->dev, "m41t00_set: Write error\n");
 }
 
 static ulong new_time;
@@ -159,6 +177,47 @@ m41t00_set_rtc_time(ulong nowtime)
 /*
  *****************************************************************************
  *
+ *	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,
+	},
+};
+
+/*
+ *****************************************************************************
+ *
  *	Driver Interface
  *
  *****************************************************************************
@@ -168,24 +227,90 @@ m41t00_probe(struct i2c_adapter *adap, i
 {
 	struct i2c_client *client;
 	int rc;
+	u8 rbuf[1], wbuf[2], msgbuf[1] = { 0 }; /* offset into rtc's regs */
+	struct i2c_msg msgs[] = {
+		{ 0, 0, 1, msgbuf },
+		{ 0, I2C_M_RD, 1, rbuf }
+	};
 
 	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_driver.driver.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)) != 0)
+		goto attach_err;
+
+	msgs[0].addr = addr;
+	msgs[1].addr = addr;
+
+	if (m41t00_chip->type != M41T00_TYPE_M41T00) {
+		/* If asked, set SQW frequency & enable */
+		if (m41t00_chip->sqw_freq) {
+			msgbuf[0] = m41t00_chip->alarm_mon;
+			if ((rc = i2c_transfer(client->adapter, msgs, 2)) < 0)
+				goto sqw_err;
+
+			wbuf[0] = m41t00_chip->alarm_mon;
+			wbuf[1] = rbuf[0] & ~0x40;
+			if ((rc = i2c_master_send(client, wbuf, 2)) < 0)
+				goto sqw_err;
+
+			wbuf[0] = m41t00_chip->sqw;
+			wbuf[1] = m41t00_chip->sqw_freq;
+			if ((rc = i2c_master_send(client, wbuf, 2)) < 0)
+				goto sqw_err;
+
+			wbuf[0] = m41t00_chip->alarm_mon;
+			wbuf[1] = rbuf[0] | 0x40;
+			if ((rc = i2c_master_send(client, wbuf, 2)) < 0)
+				goto sqw_err;
+		}
+
+		/* Make sure HT (Halt Update) bit is cleared */
+		msgbuf[0] = m41t00_chip->alarm_hour;
+		if ((rc = i2c_transfer(client->adapter, msgs, 2)) < 0)
+			goto ht_err;
+
+		if (rbuf[0] & 0x40) {
+			wbuf[0] = m41t00_chip->alarm_hour;
+			wbuf[1] = rbuf[0] & ~0x40;
+			if ((rc = i2c_master_send(client, wbuf, 2)) < 0)
+				goto ht_err;
+		}
+	}
+
+	/* Make sure ST (stop) bit is cleared */
+	msgbuf[0] = m41t00_chip->sec;
+	if ((rc = i2c_transfer(client->adapter, msgs, 2)) < 0)
+		goto st_err;
+
+	if (rbuf[0] & 0x80) {
+		wbuf[0] = m41t00_chip->sec;
+		wbuf[1] = rbuf[0] & ~0x80;
+		if ((rc = i2c_master_send(client, wbuf, 2)) < 0)
+			goto st_err;
 	}
 
 	INIT_WORK(&set_rtc_time_task, &m41t00_set, &new_time);
 	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 +344,18 @@ 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);
diff -Nurp linux-2.6.16-mm1-cleanup/include/linux/m41t00.h linux-2.6.16-mm1-newsupp/include/linux/m41t00.h
--- linux-2.6.16-mm1-cleanup/include/linux/m41t00.h	1969-12-31 17:00:00.000000000 -0700
+++ linux-2.6.16-mm1-newsupp/include/linux/m41t00.h	2006-03-23 17:54:54.000000000 -0700
@@ -0,0 +1,50 @@
+/*
+ * Definitions for the ST M41T00 family of i2c rtc chips.
+ *
+ * Author: Mark A. Greer <mgreer@xxxxxxxxxx>
+ *
+ * 2005 (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.
+ */
+
+#ifndef _M41T00_H
+#define _M41T00_H
+
+#define	M41T00_DRV_NAME		"m41t00"
+#define	M41T00_I2C_ADDR		0x68
+
+#define	M41T00_TYPE_M41T00	0
+#define	M41T00_TYPE_M41T81	81
+#define	M41T00_TYPE_M41T85	85
+
+struct m41t00_platform_data {
+	u16	type;
+	u16	i2c_addr;
+	u32	sqw_freq;
+};
+
+/* SQW output disabled, this is default value by power on*/
+#define SQW_FREQ_DISABLE	(0)
+
+#define SQW_FREQ_32KHZ	(1<<4)		/* 32.768 KHz */
+#define SQW_FREQ_8KHZ	(2<<4)		/* 8.192 KHz */
+#define SQW_FREQ_4KHZ	(3<<4)		/* 4.096 KHz */
+#define SQW_FREQ_2KHZ	(4<<4)		/* 2.048 KHz */
+#define SQW_FREQ_1KHZ	(5<<4)		/* 1.024 KHz */
+#define SQW_FREQ_512HZ	(6<<4)		/* 512 Hz */
+#define SQW_FREQ_256HZ	(7<<4)		/* 256 Hz */
+#define SQW_FREQ_128HZ	(8<<4)		/* 128 Hz */
+#define SQW_FREQ_64HZ	(9<<4)		/* 64 Hz */
+#define SQW_FREQ_32HZ	(10<<4)		/* 32 Hz */
+#define SQW_FREQ_16HZ	(11<<4)		/* 16 Hz */
+#define SQW_FREQ_8HZ	(12<<4)		/* 8 Hz */
+#define SQW_FREQ_4HZ	(13<<4)		/* 4 Hz */
+#define SQW_FREQ_2HZ	(14<<4)		/* 2 Hz */
+#define SQW_FREQ_1HZ	(15<<4)		/* 1 Hz */
+
+extern ulong m41t00_get_rtc_time(void);
+extern int m41t00_set_rtc_time(ulong nowtime);
+
+#endif /* _M41T00_H */
-
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