ipmi: remove open coded version of SMBus block write

The block-write function of the core was not used because there was no
client-struct to use. However, in this case it seems apropriate to use a
temporary client struct. Because we are answering a request we recieved
when being a client ourselves. So, convert the code to use a temporary
client and use the block-write function of the I2C core.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Asmaa Mnebhi <asmaa@nvidia.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Message-Id: <20210128085544.7609-1-wsa+renesas@sang-engineering.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmb_dev_int.c

@@ -137,7 +137,7 @@ static ssize_t ipmb_write(struct file *file, const char __user *buf,
 {
 	struct ipmb_dev *ipmb_dev = to_ipmb_dev(file);
 	u8 rq_sa, netf_rq_lun, msg_len;
-	union i2c_smbus_data data;
+	struct i2c_client *temp_client;
 	u8 msg[MAX_MSG_LEN];
 	ssize_t ret;
 
@@ -160,21 +160,21 @@ static ssize_t ipmb_write(struct file *file, const char __user *buf,
 	}
 
 	/*
-	 * subtract rq_sa and netf_rq_lun from the length of the msg passed to
-	 * i2c_smbus_xfer
+	 * subtract rq_sa and netf_rq_lun from the length of the msg. Fill the
+	 * temporary client. Note that its use is an exception for IPMI.
 	 */
 	msg_len = msg[IPMB_MSG_LEN_IDX] - SMBUS_MSG_HEADER_LENGTH;
-	if (msg_len > I2C_SMBUS_BLOCK_MAX)
-		msg_len = I2C_SMBUS_BLOCK_MAX;
+	temp_client = kmemdup(ipmb_dev->client, sizeof(*temp_client), GFP_KERNEL);
+	if (!temp_client)
+		return -ENOMEM;
+
+	temp_client->addr = rq_sa;
 
-	data.block[0] = msg_len;
-	memcpy(&data.block[1], msg + SMBUS_MSG_IDX_OFFSET, msg_len);
-	ret = i2c_smbus_xfer(ipmb_dev->client->adapter, rq_sa,
-			     ipmb_dev->client->flags,
-			     I2C_SMBUS_WRITE, netf_rq_lun,
-			     I2C_SMBUS_BLOCK_DATA, &data);
+	ret = i2c_smbus_write_block_data(temp_client, netf_rq_lun, msg_len,
+					 msg + SMBUS_MSG_IDX_OFFSET);
+	kfree(temp_client);
 
-	return ret ? : count;
+	return ret < 0 ? ret : count;
 }
 
 static __poll_t ipmb_poll(struct file *file, poll_table *wait)