i2c: octeon: Support I2C_M_RECV_LEN

BugLink: https://bugs.launchpad.net/bugs/1688132

If I2C_M_RECV_LEN is set consider the length byte.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
(cherry picked from commit 886f6f83)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/i2c/busses/i2c-octeon.c

@@ -315,16 +315,17 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
  * @i2c: The struct octeon_i2c
  * @target: Target address
  * @data: Pointer to the location to store the data
- * @length: Length of the data
+ * @rlength: Length of the data
+ * @recv_len: flag for length byte
  *
  * The address is sent over the bus, then the data is read.
  *
  * Returns 0 on success, otherwise a negative errno.
  */
 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
-			   u8 *data, int length)
+			   u8 *data, u16 *rlength, bool recv_len)
 {
-	int i, result;
+	int i, result, length = *rlength;
 	u8 tmp;
 
 	if (length < 1)
@@ -363,7 +364,17 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 			return result;
 
 		data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
+		if (recv_len && i == 0) {
+			if (data[i] > I2C_SMBUS_BLOCK_MAX + 1) {
+				dev_err(i2c->dev,
+					"%s: read len > I2C_SMBUS_BLOCK_MAX %d\n",
+					__func__, data[i]);
+				return -EPROTO;
+			}
+			length += data[i];
+		}
 	}
+	*rlength = length;
 	return 0;
 }
 
@@ -390,7 +401,7 @@ static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			 pmsg->len, pmsg->addr, i + 1, num);
 		if (pmsg->flags & I2C_M_RD)
 			ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
-					      pmsg->len);
+					      &pmsg->len, pmsg->flags & I2C_M_RECV_LEN);
 		else
 			ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
 					       pmsg->len);
@@ -402,7 +413,8 @@ static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+	       I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
 }
 
 static const struct i2c_algorithm octeon_i2c_algo = {