[PATCH RFC v3 04/14] i2c: core: add i2c_xfer_to_xfer_v2() helper function

[Dmitry Guzman]

If an I2C bus driver implements i2c_xfer_v2() callback for multi-message
transfer with detailed reporting in its struct i2c_algorithm, it still
must have old xfer() callback for backward compatibility because this
callback sometimes is checked or called directly, without using
i2c_transfer().

To avoid code duplication for drivers that do not need different code
for transfer with and without detailed reporting enabled, provide a
helper function i2c_xfer_to_xfer_v2() that calls xfer_v2() with pointer
to a dummy struct i2c_transfer_report that will be dropped after using.

It should be used in xfer field of struct i2c_algorithm.

Signed-off-by: Dmitry Guzman <Dmitry.Guzman@xxxxxxxxxxxx>
---
 drivers/i2c/i2c-core-base.c | 8 ++++++++
 include/linux/i2c.h         | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 165ec14260c8..12b49c01baed 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2400,6 +2400,14 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 }
 EXPORT_SYMBOL(i2c_transfer);
 
+int i2c_xfer_to_xfer_v2(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct i2c_transfer_report dummy_report;
+
+	return adap->algo->xfer_v2(adap, msgs, num, &dummy_report);
+}
+EXPORT_SYMBOL(i2c_xfer_to_xfer_v2);
+
 /**
  * i2c_transfer_buffer_flags - issue a single I2C message transferring data
  *			       to/from a buffer
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 9bee726592fc..6a4df8562ab4 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -601,6 +601,8 @@ struct i2c_algorithm {
 #endif
 };
 
+int i2c_xfer_to_xfer_v2(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
+
 static inline void i2c_transfer_report_init(struct i2c_transfer_report *report)
 {
 	report->msgs_cplt = -EOPNOTSUPP;

-- 
2.43.0