Refactor the current implementation of the high-level composite read and
write operations in preparation of the addition of block-mode read/write
operations.

The sending of the i2c command is generic and will apply for both the
block-mode and non-block-mode ops. Extract this from the current hlc
ops, and place into a generic function, octeon_i2c_hlc_cmd_send.

The considerations made for extended addresses in the command
construction are almost common for all cases, extract these into
octeon_i2c_hlc_ext. There is one difference between the extended read
and write cases. When performing extended read or writes the SW_TWSI_EXT
must be written with an extended internal address, but the data field is
only filled in the write case (read back in read case). This results in
the original code block for the read case immediately writing this
register, while the write case fills in any data and then writes the
register. To create a common block of code for both processes remove the
SW_TWSI_EXT write from within the code block and instead in it's place a
variable is set, set_ext, which is returned and used as a condition to
do the register write, in the read command case.

There are parts of the commands construction which are common (only in
the read case), extract this and place into generic function
octeon_i2c_hlc_read_cmd. This function also reads the return from
octeon_i2c_hlc_ext and completes the write to SW_TWSI_EXT if required.

The write commands cannot be made entirely into common code as there are
distinct differences in the block mode and non-block-mode process.
Particularly the writing of data into the buffer.

Signed-off-by: Aryan Srivastava <aryan.srivastava@alliedtelesis.co.nz>
---
 drivers/i2c/busses/i2c-octeon-core.c | 86 ++++++++++++++++------------
 1 file changed, 49 insertions(+), 37 deletions(-)

diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
index 16cc34a0526e..3fbc828508ab 100644
--- a/drivers/i2c/busses/i2c-octeon-core.c
+++ b/drivers/i2c/busses/i2c-octeon-core.c
@@ -498,6 +498,50 @@ static int octeon_i2c_hlc_write(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 	return ret;
 }
 
+/* Process hlc transaction */
+static int octeon_i2c_hlc_cmd_send(struct octeon_i2c *i2c, u64 cmd)
+{
+	octeon_i2c_hlc_int_clear(i2c);
+	octeon_i2c_writeq_flush(cmd, i2c->twsi_base + OCTEON_REG_SW_TWSI(i2c));
+
+	return octeon_i2c_hlc_wait(i2c);
+}
+
+/* Generic consideration for extended internal addresses in i2c hlc r/w ops */
+static bool octeon_i2c_hlc_ext(struct octeon_i2c *i2c, struct i2c_msg msg, u64 *cmd_in, u64 *ext)
+{
+	bool set_ext = false;
+	u64 cmd = 0;
+
+	if (msg.flags & I2C_M_TEN)
+		cmd |= SW_TWSI_OP_10_IA;
+	else
+		cmd |= SW_TWSI_OP_7_IA;
+
+	if (msg.len == 2) {
+		cmd |= SW_TWSI_EIA;
+		*ext = (u64)msg.buf[0] << SW_TWSI_IA_SHIFT;
+		cmd |= (u64)msg.buf[1] << SW_TWSI_IA_SHIFT;
+		set_ext = true;
+	} else {
+		cmd |= (u64)msg.buf[0] << SW_TWSI_IA_SHIFT;
+	}
+
+	*cmd_in |= cmd;
+	return set_ext;
+}
+
+/* Construct and send i2c transaction core cmd for read ops */
+static int octeon_i2c_hlc_read_cmd(struct octeon_i2c *i2c, struct i2c_msg msg, u64 cmd)
+{
+	u64 ext = 0;
+
+	if (octeon_i2c_hlc_ext(i2c, msg, &cmd, &ext))
+		octeon_i2c_writeq_flush(ext, i2c->twsi_base + OCTEON_REG_SW_TWSI_EXT(i2c));
+
+	return octeon_i2c_hlc_cmd_send(i2c, cmd);
+}
+
 /* high-level-controller composite write+read, msg0=addr, msg1=data */
 static int octeon_i2c_hlc_comp_read(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 {
@@ -512,26 +556,8 @@ static int octeon_i2c_hlc_comp_read(struct octeon_i2c *i2c, struct i2c_msg *msgs
 	/* A */
 	cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 
-	if (msgs[0].flags & I2C_M_TEN)
-		cmd |= SW_TWSI_OP_10_IA;
-	else
-		cmd |= SW_TWSI_OP_7_IA;
-
-	if (msgs[0].len == 2) {
-		u64 ext = 0;
-
-		cmd |= SW_TWSI_EIA;
-		ext = (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
-		cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
-		octeon_i2c_writeq_flush(ext, i2c->twsi_base + OCTEON_REG_SW_TWSI_EXT(i2c));
-	} else {
-		cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
-	}
-
-	octeon_i2c_hlc_int_clear(i2c);
-	octeon_i2c_writeq_flush(cmd, i2c->twsi_base + OCTEON_REG_SW_TWSI(i2c));
-
-	ret = octeon_i2c_hlc_wait(i2c);
+	/* Send core command */
+	ret = octeon_i2c_hlc_read_cmd(i2c, msgs[0], cmd);
 	if (ret)
 		goto err;
 
@@ -567,19 +593,8 @@ static int octeon_i2c_hlc_comp_write(struct octeon_i2c *i2c, struct i2c_msg *msg
 	/* A */
 	cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 
-	if (msgs[0].flags & I2C_M_TEN)
-		cmd |= SW_TWSI_OP_10_IA;
-	else
-		cmd |= SW_TWSI_OP_7_IA;
-
-	if (msgs[0].len == 2) {
-		cmd |= SW_TWSI_EIA;
-		ext |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
-		set_ext = true;
-		cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
-	} else {
-		cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
-	}
+	/* Set parameters for extended message (if required) */
+	set_ext = octeon_i2c_hlc_ext(i2c, msgs[0], &cmd, &ext);
 
 	for (i = 0, j = msgs[1].len - 1; i  < msgs[1].len && i < 4; i++, j--)
 		cmd |= (u64)msgs[1].buf[j] << (8 * i);
@@ -592,10 +607,7 @@ static int octeon_i2c_hlc_comp_write(struct octeon_i2c *i2c, struct i2c_msg *msg
 	if (set_ext)
 		octeon_i2c_writeq_flush(ext, i2c->twsi_base + OCTEON_REG_SW_TWSI_EXT(i2c));
 
-	octeon_i2c_hlc_int_clear(i2c);
-	octeon_i2c_writeq_flush(cmd, i2c->twsi_base + OCTEON_REG_SW_TWSI(i2c));
-
-	ret = octeon_i2c_hlc_wait(i2c);
+	ret = octeon_i2c_hlc_cmd_send(i2c, cmd);
 	if (ret)
 		goto err;
 
-- 
2.46.0