include/device/i2c_simple: add i2c_2ba_read_bytes function

To read data from an I2C EEPROM that uses 2 byte offsets or any other
I2C device that uses 2 byte offsets, first the two offset bytes are sent
to the device and then the data bytes are read from it. The main
difference to the existing i2c_read_bytes is that that function will
only send one offset byte to the I2C device.

TEST=Reading the contents of an EEPROM on the AMD Chausie board works

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I224e434bb2654aabef6302c1525112e44c4b21fa
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63791
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Fred Reitberger <reitbergerfred@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/src/include/device/i2c_simple.h b/src/include/device/i2c_simple.h
index 8f389b310725..9f3af1130e11 100644
--- a/src/include/device/i2c_simple.h
+++ b/src/include/device/i2c_simple.h
@@ -142,4 +142,32 @@ static inline int i2c_writeb(unsigned int bus, uint8_t slave, uint8_t reg,
 	return i2c_transfer(bus, &seg, 1);
 }
 
+/**
+ * Read multi-bytes from an I2C device with two bytes register address/offset
+ * with two segments in one frame
+ *
+ * [start][slave addr][w][register high addr][register low addr]
+ * [start][slave addr][r][data...][stop]
+ */
+static inline int i2c_2ba_read_bytes(unsigned int bus, uint8_t slave, uint16_t offset,
+				     uint8_t *data, int len)
+{
+	struct i2c_msg seg[2];
+	uint8_t eeprom_offset[2];
+
+	eeprom_offset[0] = offset >> 8;
+	eeprom_offset[1] = offset & 0xff;
+
+	seg[0].flags = 0;
+	seg[0].slave = slave;
+	seg[0].buf   = eeprom_offset;
+	seg[0].len   = sizeof(eeprom_offset);
+	seg[1].flags = I2C_M_RD;
+	seg[1].slave = slave;
+	seg[1].buf   = data;
+	seg[1].len   = len;
+
+	return i2c_transfer(bus, seg, ARRAY_SIZE(seg));
+}
+
 #endif	/* _DEVICE_I2C_SIMPLE_H_ */