i2c: Add option for calling board-specific functions before and after every i2c transaction

This change adds a new config option CONFIG_I2C_XFER_CALLBACK that
makes i2c_xfer callback into board-provided functions before the start
and after the end of every I2C transaction. This can be used by boards
to implement any I2C device-specific quirks e.g. requiring minimum
bus-free time between every I2C transaction when the slave device
cannot actually do clock stretching.

BUG=b:73147310
BRANCH=None
TEST=make -j buildall

Change-Id: I452de4f22a81ffd97ca4944e1b940a3537637df9
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://chromium-review.googlesource.com/956934
Commit-Ready: Furquan Shaikh <furquan@chromium.org>
Tested-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/i2c.h b/include/i2c.h
index 63169ec055..78038ea6af 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -335,4 +335,27 @@ void i2cm_init(void);
  * @return true, if passthru should be allowed on the port.
  */
 int board_allow_i2c_passthru(int port);
+
+/**
+ * Function to allow board to take any action before starting a new i2c
+ * transaction on a given port. Board must implement this if it defines
+ * CONFIG_I2C_XFER_BOARD_CALLBACK.
+ *
+ * @param port: I2C port number
+ * @param slave_addr: Slave device address
+ *
+ */
+void i2c_start_xfer_notify(int port, int slave_addr);
+
+/**
+ * Function to allow board to take any action after an i2c transaction on a
+ * given port has completed. Board must implement this if it defines
+ * CONFIG_I2C_XFER_BOARD_CALLBACK.
+ *
+ * @param port: I2C port number
+ * @param slave_addr: Slave device address
+ *
+ */
+void i2c_end_xfer_notify(int port, int slave_addr);
+
 #endif  /* __CROS_EC_I2C_H */