1) As a slight optimization, pull some logic out of the byte 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. 2) Clear INTR after clearing BYTE_DONE per ICH10 datasheet [1] pg. 711: When the last byte of a block message is received, the host controller sets DS. However, it does not set the INTR bit (and generate another interrupt) until DS is cleared. Thus, for a block message of n bytes, the ICH10 will generate n+1 interrupts. 3) If DEV_ERR is set in polling loop, abort the transaction and return -ENXIO to the caller. DEV_ERR is set if the device does not respond with an acknowledge, and the SMBus controller times out (minimum 25ms). [1] http://www.intel.com/content/dam/doc/datasheet/io-controller-hub-10-family-datasheet.pdf Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> --- drivers/i2c/busses/i2c-i801.c | 45 ++++++++++++++++++++++++---------------- 1 files changed, 27 insertions(+), 18 deletions(-) diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c index ab26840d..f3418cf 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -116,8 +116,7 @@ #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 */ @@ -320,7 +319,7 @@ static int i801_block_transaction_by_block(struct i801_priv *priv, } status = i801_transaction(priv, I801_BLOCK_DATA | ENABLE_INT9 | - I801_PEC_EN * hwpec); + (hwpec ? I801_PEC_EN : 0)); if (status) return status; @@ -336,6 +335,10 @@ static int i801_block_transaction_by_block(struct i801_priv *priv, return 0; } +/* + * 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, @@ -358,19 +361,15 @@ 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) @@ -382,8 +381,9 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, do { msleep(1); status = inb_p(SMBHSTSTS(priv)); - } while ((!(status & SMBHSTSTS_BYTE_DONE)) - && (timeout++ < MAX_TIMEOUT)); + } while (!(status & SMBHSTSTS_BYTE_DONE) && + !(status & SMBHSTSTS_DEV_ERR) && + timeout++ < MAX_TIMEOUT); result = i801_check_post(priv, status, timeout > MAX_TIMEOUT); if (result < 0) @@ -414,8 +414,17 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, outb_p(data->block[i+1], SMBBLKDAT(priv)); /* signals SMBBLKDAT ready */ - outb_p(SMBHSTSTS_BYTE_DONE | SMBHSTSTS_INTR, SMBHSTSTS(priv)); + outb_p(SMBHSTSTS_BYTE_DONE, SMBHSTSTS(priv)); + } + + /* Wait for command-completion interrupt so we can clear it */ + timeout = 0; + status = inb_p(SMBHSTSTS(priv)); + while (!(status & SMBHSTSTS_INTR) && timeout++ < MAX_TIMEOUT) { + msleep(1); + status = inb_p(SMBHSTSTS(priv)); } + outb_p(SMBHSTSTS_INTR, SMBHSTSTS(priv)); return 0; } -- 1.7.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
