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i2c: Emulate SMBus block read over I2C 

Let the I2C bus drivers emulate the SMBus Block Read and Block Process
Call transactions if they wish. This requires to define a new message
flag, which i2c-core will use to let the underlying I2C bus driver
know that the first received byte will specify the length of the read
message.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Jean Delvare 2007-05-01 23:26:29 +02:00 committed by Jean Delvare
parent 1ecac07aba
commit 209d27c3b1
2 changed files with 27 additions and 8 deletions
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32
drivers/i2c/i2c-core.c
View File

@ -590,8 +590,9 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num)
#ifdef DEBUG
for (ret = 0; ret < num; ret++) {
dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
"len=%d\n", ret, msgs[ret].flags & I2C_M_RD ?
'R' : 'W', msgs[ret].addr, msgs[ret].len);
"len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
(msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
}
#endif
@ -1050,9 +1051,9 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr,
break;
case I2C_SMBUS_BLOCK_DATA:
if (read_write == I2C_SMBUS_READ) {
dev_err(&adapter->dev, "Block read not supported "
"under I2C emulation!\n");
return -1;
msg[1].flags |= I2C_M_RECV_LEN;
msg[1].len = 1; /* block length will be added by
the underlying bus driver */
} else {
msg[0].len = data->block[0] + 2;
if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
@ -1066,9 +1067,21 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr,
}
break;
case I2C_SMBUS_BLOCK_PROC_CALL:
dev_dbg(&adapter->dev, "Block process call not supported "
"under I2C emulation!\n");
num = 2; /* Another special case */
read_write = I2C_SMBUS_READ;
if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
dev_err(&adapter->dev, "%s called with invalid "
"block proc call size (%d)\n", __FUNCTION__,
data->block[0]);
return -1;
}
msg[0].len = data->block[0] + 2;
for (i = 1; i < msg[0].len; i++)
msgbuf0[i] = data->block[i-1];
msg[1].flags |= I2C_M_RECV_LEN;
msg[1].len = 1; /* block length will be added by
the underlying bus driver */
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
if (read_write == I2C_SMBUS_READ) {
msg[1].len = I2C_SMBUS_BLOCK_MAX;
@ -1132,6 +1145,11 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr,
for (i = 0; i < I2C_SMBUS_BLOCK_MAX; i++)
data->block[i+1] = msgbuf1[i];
break;
case I2C_SMBUS_BLOCK_DATA:
case I2C_SMBUS_BLOCK_PROC_CALL:
for (i = 0; i < msgbuf1[0] + 1; i++)
data->block[i] = msgbuf1[i];
break;
}
return 0;
}

1
include/linux/i2c.h
View File

@ -366,6 +366,7 @@ struct i2c_msg {
#define I2C_M_REV_DIR_ADDR 0x2000
#define I2C_M_IGNORE_NAK 0x1000
#define I2C_M_NO_RD_ACK 0x0800
#define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */
__u16 len; /* msg length */
__u8 *buf; /* pointer to msg data */
};