From 23abfe1a27c30fb76c8127cdab3603d95b214486 Mon Sep 17 00:00:00 2001 From: Daniel Kurtz Date: Wed, 25 Jul 2012 09:25:02 +1000 Subject: [PATCH] i2c-i801: Refactor use of LAST_BYTE in i801_block_transaction_byte_by_byte As a slight optimization, pull some logic out of the polling loop during byte-by-byte transactions by just setting the I801_LAST_BYTE bit, as defined in the i801 (PCH) datasheet, when reading the last byte of a byte-by-byte I2C_SMBUS_READ. Signed-off-by: Daniel Kurtz Signed-off-by: Jean Delvare --- drivers/i2c/busses/i2c-i801.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c index ae2945a5e007..51e11eb64abc 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -117,8 +117,7 @@ #define I801_PROC_CALL 0x10 /* unimplemented */ #define I801_BLOCK_DATA 0x14 #define I801_I2C_BLOCK_DATA 0x18 /* ICH5 and later */ -#define I801_BLOCK_LAST 0x34 -#define I801_I2C_BLOCK_LAST 0x38 /* ICH5 and later */ +#define I801_LAST_BYTE 0x20 #define I801_START 0x40 #define I801_PEC_EN 0x80 /* ICH3 and later */ @@ -338,6 +337,11 @@ static int i801_block_transaction_by_block(struct i801_priv *priv, return 0; } +/* + * For "byte-by-byte" block transactions: + * I2C write uses cmd=I801_BLOCK_DATA, I2C_EN=1 + * I2C read uses cmd=I801_I2C_BLOCK_DATA + */ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, union i2c_smbus_data *data, char read_write, int command, @@ -360,19 +364,15 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, outb_p(data->block[1], SMBBLKDAT(priv)); } + if (command == I2C_SMBUS_I2C_BLOCK_DATA && + read_write == I2C_SMBUS_READ) + smbcmd = I801_I2C_BLOCK_DATA; + else + smbcmd = I801_BLOCK_DATA; + for (i = 1; i <= len; i++) { - if (i == len && read_write == I2C_SMBUS_READ) { - if (command == I2C_SMBUS_I2C_BLOCK_DATA) - smbcmd = I801_I2C_BLOCK_LAST; - else - smbcmd = I801_BLOCK_LAST; - } else { - if (command == I2C_SMBUS_I2C_BLOCK_DATA - && read_write == I2C_SMBUS_READ) - smbcmd = I801_I2C_BLOCK_DATA; - else - smbcmd = I801_BLOCK_DATA; - } + if (i == len && read_write == I2C_SMBUS_READ) + smbcmd |= I801_LAST_BYTE; outb_p(smbcmd | ENABLE_INT9, SMBHSTCNT(priv)); if (i == 1) -- 2.39.5