linux-kernel - [PATCH v3 2/3] i2c: smbus: use get/put_unaligned

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Date:   Tue, 12 Nov 2019 12:31:31 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     linux-iio@...r.kernel.orgi, Luca Ceresoli <luca@...aceresoli.net>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/3] i2c: smbus: use get/put_unaligned_le16 when working with word data

It is potentially more performant, and also shows intent more clearly,
to use get_unaligned_le16() and put_unaligned_le16() when working with
word data.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

---

Changes in v3:
- split put_unaligned_le16 into a separate patch
- more call sites converted to get/put_unaligned_le16

 drivers/i2c/i2c-core-smbus.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index f8708409b4dbc..7b4e2270eeda1 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -15,6 +15,7 @@
 #include <linux/i2c.h>
 #include <linux/i2c-smbus.h>
 #include <linux/slab.h>
+#include <asm/unaligned.h>
 
 #include "i2c-core.h"
 
@@ -370,8 +371,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 			msg[1].len = 2;
 		else {
 			msg[0].len = 3;
-			msgbuf0[1] = data->word & 0xff;
-			msgbuf0[2] = data->word >> 8;
+			put_unaligned_le16(data->word, msgbuf0 + 1);
 		}
 		break;
 	case I2C_SMBUS_PROC_CALL:
@@ -379,8 +379,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 		read_write = I2C_SMBUS_READ;
 		msg[0].len = 3;
 		msg[1].len = 2;
-		msgbuf0[1] = data->word & 0xff;
-		msgbuf0[2] = data->word >> 8;
+		put_unaligned_le16(data->word, msgbuf0 + 1);
 		break;
 	case I2C_SMBUS_BLOCK_DATA:
 		if (read_write == I2C_SMBUS_READ) {
@@ -487,7 +486,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 			break;
 		case I2C_SMBUS_WORD_DATA:
 		case I2C_SMBUS_PROC_CALL:
-			data->word = msgbuf1[0] | (msgbuf1[1] << 8);
+			data->word = get_unaligned_le16(msgbuf1);
 			break;
 		case I2C_SMBUS_I2C_BLOCK_DATA:
 			for (i = 0; i < data->block[0]; i++)
@@ -648,8 +647,7 @@ s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
 			status = i2c_smbus_read_word_data(client, command + i);
 			if (status < 0)
 				return status;
-			bytes[i] = status & 0xff;
-			bytes[i + 1] = status >> 8;
+			put_unaligned_le16(status, values + i);
 			i += 2;
 		}
 	}
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog