[U-Boot] [RFC/PATCH] cros_ec: i2c: Group i2c write / read into single transaction

[Moritz Fischer]

Replace dm_i2c_write() / dm_i2c_read() with transaction using
struct i2c_msg[2] in order to allow for i2c controller to detect
write/read cycle to emit a repeated start condition.

Signed-off-by: Moritz Fischer <moritz.fischer at ettus.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: u-boot at lists.denx.de
---
Hi Simon,

since I don't have a v2 protocol EC I couldn't test this,
but I noticed when playing around with a v3 one, that it would simply ignore
the packets if they don't have a repeated start condition (which from my understanding)
you can *only* get if you use struct i2c_msg, since otherwise the driver has no way of
knowing your intention.

Do you have a v2 board around to test this?

Cheers,

Moritz
---
 drivers/misc/cros_ec_i2c.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/misc/cros_ec_i2c.c b/drivers/misc/cros_ec_i2c.c
index 3de18b2..f2f6961 100644
--- a/drivers/misc/cros_ec_i2c.c
+++ b/drivers/misc/cros_ec_i2c.c
@@ -29,6 +29,8 @@ static int cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
 			       int dout_len, uint8_t **dinp, int din_len)
 {
 	struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
+	struct dm_i2c_chip *chip = dev_get_parent_platdata(udev);
+	struct i2c_msg i2c_msg[2];
 	/* version8, cmd8, arglen8, out8[dout_len], csum8 */
 	int out_bytes = dout_len + 4;
 	/* response8, arglen8, in8[din_len], checksum8 */
@@ -53,6 +55,11 @@ static int cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
 	assert(dout_len >= 0);
 	assert(dinp);
 
+	i2c_msg[0].addr = chip->chip_addr;
+	i2c_msg[0].len = out_bytes;
+	i2c_msg[0].buf = dev->dout;
+	i2c_msg[0].flags = 0;
+
 	/*
 	 * Copy command and data into output buffer so we can do a single I2C
 	 * burst transaction.
@@ -85,24 +92,21 @@ static int cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
 	*ptr++ = (uint8_t)
 		cros_ec_calc_checksum(dev->dout, dout_len + 3);
 
+	i2c_msg[1].addr = chip->chip_addr;
+	i2c_msg[1].len = in_bytes;
+	i2c_msg[1].buf = in_ptr;
+	i2c_msg[1].flags = I2C_M_RD;
+
 	/* Send output data */
 	cros_ec_dump_data("out", -1, dev->dout, out_bytes);
-	ret = dm_i2c_write(udev, 0, dev->dout, out_bytes);
+
+	ret = dm_i2c_xfer(udev, &i2c_msg[0], 2);
 	if (ret) {
-		debug("%s: Cannot complete I2C write to %s\n", __func__,
+		debug("%s: Could not execute transfer to %s\n", __func__,
 		      udev->name);
 		ret = -1;
 	}
 
-	if (!ret) {
-		ret = dm_i2c_read(udev, 0, in_ptr, in_bytes);
-		if (ret) {
-			debug("%s: Cannot complete I2C read from %s\n",
-			      __func__, udev->name);
-			ret = -1;
-		}
-	}
-
 	if (*in_ptr != EC_RES_SUCCESS) {
 		debug("%s: Received bad result code %d\n", __func__, *in_ptr);
 		return -(int)*in_ptr;
-- 
2.7.4