i2c: iproc: add support for SMBUS quick cmd

Add support for SMBUS quick command.

SMBUS quick command passes single bit of information to the
slave (target) device. Can be used to turn slave device on or off.

By default i2c_detect tool uses the smbus quick cmd to try and
detect devices. Without this support it will not detect some slaves.
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-bcm-iproc.c

@@ -79,6 +79,7 @@
 #define M_CMD_STATUS_RX_FIFO_FULL    0x6
 #define M_CMD_PROTOCOL_SHIFT         9
 #define M_CMD_PROTOCOL_MASK          0xf
+#define M_CMD_PROTOCOL_QUICK         0x0
 #define M_CMD_PROTOCOL_BLK_WR        0x7
 #define M_CMD_PROTOCOL_BLK_RD        0x8
 #define M_CMD_PROTOCOL_PROCESS       0xa
@@ -765,7 +766,11 @@ static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
 	 * number of bytes to read
 	 */
 	val = BIT(M_CMD_START_BUSY_SHIFT);
-	if (msg->flags & I2C_M_RD) {
+
+	if (msg->len == 0) {
+		/* SMBUS QUICK Command (Read/Write) */
+		val |= (M_CMD_PROTOCOL_QUICK << M_CMD_PROTOCOL_SHIFT);
+	} else if (msg->flags & I2C_M_RD) {
 		u32 protocol;
 
 		iproc_i2c->rx_bytes = 0;
@@ -827,8 +832,7 @@ static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
 {
 	u32 val;
 
-	/* We do not support the SMBUS Quick command */
-	val = I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+	val = I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 
 	if (adap->algo->reg_slave)
 		val |= I2C_FUNC_SLAVE;