[PATCH 3/6] mfd: 88pm860x: enhance lock on i2c transaction

[Haojian Zhuang]

Accessing test page in 88pm860x is a sequence of read/write on i2c bus.
Bus lock is used in each small i2c transaction. But it may result the
whole sequence interrupted by other i2c client transaction.

Use i2c_lock_adapter()/i2c_unlock_adapter() to protect the sequence and
use master_xfer() to send i2c message.

Signed-off-by: Haojian Zhuang <haojian.zhuang@xxxxxxxxxxx>
Cc: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Cc: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Ben Dooks <ben-linux@xxxxxxxxx>
---
 drivers/mfd/88pm860x-i2c.c |  112 +++++++++++++++++++++++++++++++------------
 1 files changed, 81 insertions(+), 31 deletions(-)

diff --git a/drivers/mfd/88pm860x-i2c.c b/drivers/mfd/88pm860x-i2c.c
index e017dc8..67a34f4 100644
--- a/drivers/mfd/88pm860x-i2c.c
+++ b/drivers/mfd/88pm860x-i2c.c
@@ -126,6 +126,51 @@ out:
 }
 EXPORT_SYMBOL(pm860x_set_bits);
 
+static int read_device(struct i2c_client *i2c, int reg,
+		       int bytes, void *dest)
+{
+	unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX + 3];
+	unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX + 2];
+	struct i2c_adapter *adap = i2c->adapter;
+	struct i2c_msg msg[2] = {{i2c->addr, i2c->flags, 1, msgbuf0},
+				 {i2c->addr, i2c->flags | I2C_M_RD, 0, msgbuf1},
+				};
+	int num = 1, ret = 0;
+
+	if (dest == NULL)
+		return -EINVAL;
+	msgbuf0[0] = (unsigned char)reg;	/* command */
+	msg[1].len = bytes;
+
+	/* if data needs to read back, num should be 2 */
+	if (bytes > 0)
+		num = 2;
+	ret = adap->algo->master_xfer(adap, msg, num);
+	memcpy(dest, msgbuf1, bytes);
+	return ret;
+}
+
+static int write_device(struct i2c_client *i2c, int reg,
+			int bytes, void *src)
+{
+	unsigned char buf[bytes + 1];
+	struct i2c_adapter *adap = i2c->adapter;
+	struct i2c_msg msg;
+	int ret;
+
+	buf[0] = (unsigned char)reg;
+	memcpy(&buf[1], src, bytes);
+	msg.addr = i2c->addr;
+	msg.flags = i2c->flags;
+	msg.len = bytes + 1;
+	msg.buf = buf;
+
+	ret = adap->algo->master_xfer(adap, &msg, 1);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
 int pm860x_page_reg_read(struct i2c_client *i2c, int reg)
 {
 	struct pm860x_chip *chip = i2c_get_clientdata(i2c);
@@ -134,14 +179,15 @@ int pm860x_page_reg_read(struct i2c_client *i2c, int reg)
 	int ret;
 
 	mutex_lock(&chip->io_lock);
-	pm860x_write_device(i2c, 0xFA, 0, &zero);
-	pm860x_write_device(i2c, 0xFB, 0, &zero);
-	pm860x_write_device(i2c, 0xFF, 0, &zero);
-	ret = pm860x_read_device(i2c, reg, 1, &data);
+	i2c_lock_adapter(i2c->adapter);
+	read_device(i2c, 0xFA, 0, &zero);
+	read_device(i2c, 0xFB, 0, &zero);
+	read_device(i2c, 0xFF, 0, &zero);
+	ret = read_device(i2c, reg, 1, &data);
 	if (ret >= 0)
 		ret = (int)data;
-	pm860x_write_device(i2c, 0xFE, 0, &zero);
-	pm860x_write_device(i2c, 0xFC, 0, &zero);
+	read_device(i2c, 0xFC, 0, &zero);
+	i2c_unlock_adapter(i2c->adapter);
 	mutex_unlock(&chip->io_lock);
 	return ret;
 }
@@ -155,12 +201,13 @@ int pm860x_page_reg_write(struct i2c_client *i2c, int reg,
 	int ret;
 
 	mutex_lock(&chip->io_lock);
-	pm860x_write_device(i2c, 0xFA, 0, &zero);
-	pm860x_write_device(i2c, 0xFB, 0, &zero);
-	pm860x_write_device(i2c, 0xFF, 0, &zero);
-	ret = pm860x_write_device(i2c, reg, 1, &data);
-	pm860x_write_device(i2c, 0xFE, 0, &zero);
-	pm860x_write_device(i2c, 0xFC, 0, &zero);
+	i2c_lock_adapter(i2c->adapter);
+	read_device(i2c, 0xFA, 0, &zero);
+	read_device(i2c, 0xFB, 0, &zero);
+	read_device(i2c, 0xFF, 0, &zero);
+	ret = write_device(i2c, reg, 1, &data);
+	read_device(i2c, 0xFC, 0, &zero);
+	i2c_unlock_adapter(i2c->adapter);
 	mutex_unlock(&chip->io_lock);
 	return ret;
 }
@@ -174,12 +221,13 @@ int pm860x_page_bulk_read(struct i2c_client *i2c, int reg,
 	int ret;
 
 	mutex_lock(&chip->io_lock);
-	pm860x_write_device(i2c, 0xFA, 0, &zero);
-	pm860x_write_device(i2c, 0xFB, 0, &zero);
-	pm860x_write_device(i2c, 0xFF, 0, &zero);
-	ret = pm860x_read_device(i2c, reg, count, buf);
-	pm860x_write_device(i2c, 0xFE, 0, &zero);
-	pm860x_write_device(i2c, 0xFC, 0, &zero);
+	i2c_lock_adapter(i2c->adapter);
+	read_device(i2c, 0xFA, 0, &zero);
+	read_device(i2c, 0xFB, 0, &zero);
+	read_device(i2c, 0xFF, 0, &zero);
+	ret = read_device(i2c, reg, count, buf);
+	read_device(i2c, 0xFC, 0, &zero);
+	i2c_unlock_adapter(i2c->adapter);
 	mutex_unlock(&chip->io_lock);
 	return ret;
 }
@@ -193,12 +241,13 @@ int pm860x_page_bulk_write(struct i2c_client *i2c, int reg,
 	int ret;
 
 	mutex_lock(&chip->io_lock);
-	pm860x_write_device(i2c, 0xFA, 0, &zero);
-	pm860x_write_device(i2c, 0xFB, 0, &zero);
-	pm860x_write_device(i2c, 0xFF, 0, &zero);
-	ret = pm860x_write_device(i2c, reg, count, buf);
-	pm860x_write_device(i2c, 0xFE, 0, &zero);
-	pm860x_write_device(i2c, 0xFC, 0, &zero);
+	i2c_lock_adapter(i2c->adapter);
+	read_device(i2c, 0xFA, 0, &zero);
+	read_device(i2c, 0xFB, 0, &zero);
+	read_device(i2c, 0xFF, 0, &zero);
+	ret = write_device(i2c, reg, count, buf);
+	read_device(i2c, 0xFC, 0, &zero);
+	i2c_unlock_adapter(i2c->adapter);
 	mutex_unlock(&chip->io_lock);
 	return ret;
 }
@@ -213,18 +262,19 @@ int pm860x_page_set_bits(struct i2c_client *i2c, int reg,
 	int ret;
 
 	mutex_lock(&chip->io_lock);
-	pm860x_write_device(i2c, 0xFA, 0, &zero);
-	pm860x_write_device(i2c, 0xFB, 0, &zero);
-	pm860x_write_device(i2c, 0xFF, 0, &zero);
-	ret = pm860x_read_device(i2c, reg, 1, &value);
+	i2c_lock_adapter(i2c->adapter);
+	read_device(i2c, 0xFA, 0, &zero);
+	read_device(i2c, 0xFB, 0, &zero);
+	read_device(i2c, 0xFF, 0, &zero);
+	ret = read_device(i2c, reg, 1, &value);
 	if (ret < 0)
 		goto out;
 	value &= ~mask;
 	value |= data;
-	ret = pm860x_write_device(i2c, reg, 1, &value);
+	ret = write_device(i2c, reg, 1, &value);
 out:
-	pm860x_write_device(i2c, 0xFE, 0, &zero);
-	pm860x_write_device(i2c, 0xFC, 0, &zero);
+	read_device(i2c, 0xFC, 0, &zero);
+	i2c_unlock_adapter(i2c->adapter);
 	mutex_unlock(&chip->io_lock);
 	return ret;
 }
-- 
1.5.6.5

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