i2c-algo-bit: Emulate SMBus block read

Now that i2c-core lets the i2c bus drivers emulate the SMBus block read
and SMBus block process call transaction types, let's implement that in
the popular i2c bit-banging driver. This will also act as a reference
implementation for other bus drivers which want to do the same.
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/algos/i2c-algo-bit.c

@@ -391,6 +391,21 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 		};
 		scllo(adap);
 		sdahi(adap);
+
+		/* Some SMBus transactions require that we receive the
+		   transaction length as the first read byte. */
+		if (rdcount == 1 && (msg->flags & I2C_M_RECV_LEN)) {
+			if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
+				printk(KERN_ERR "i2c-algo-bit: readbytes: "
+				       "invalid block length (%d)\n", inval);
+				return -EREMOTEIO;
+			}
+			/* The original count value accounts for the extra
+			   bytes, that is, either 1 for a regular transaction,
+			   or 2 for a PEC transaction. */
+			count += inval;
+			msg->len += inval;
+		}
 	}
 	return rdcount;
 }
@@ -509,6 +524,8 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 static u32 bit_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
+	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
+	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
 }