soft_i2c.c add option for repeated start in i2c_read()
This patch adds a #define to optionally change the behaviour of
i2c_read() in soft_i2c.c to send an I2C repeated start instead of a
stop-start between sending the device address pointer write and
reading back the data. The current behaviour is retained as the
default.
While most devices will work either way, I have a smart battery(*)
that requires repeated start, and someone at some point found a
device that required a stop-start.
(*) http://www.inspired-energy.com/Standard_Products/NL2054/NL2054%20Rev1.0%20Data%20Sheet.pdf
Signed-off-by: Andrew Dyer <adyer@righthandtech.com>
diff --git a/drivers/i2c/soft_i2c.c b/drivers/i2c/soft_i2c.c
index a27de5a..da6cec1 100644
--- a/drivers/i2c/soft_i2c.c
+++ b/drivers/i2c/soft_i2c.c
@@ -385,8 +385,18 @@
}
shift -= 8;
}
- send_stop(); /* reportedly some chips need a full stop */
+
+ /* Some I2C chips need a stop/start sequence here,
+ * other chips don't work with a full stop and need
+ * only a start. Default behaviour is to send the
+ * stop/start sequence.
+ */
+#ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
send_start();
+#else
+ send_stop();
+ send_start();
+#endif
}
/*
* Send the chip address again, this time for a read cycle.
