device: Add i2c read/write register field API

i2c_read_field() - read the value from the specific register field
i2c_write_field() - write the value to the specific register field

BRANCH=none
BUG=none
TEST=none

Change-Id: I2098715b4583c1936c93b3ff45ec330910964304
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 0817fc76d07491b39c066f1393a6435f0831b50c
Original-Change-Id: I92c187a89d10cfcecf3dfd9291e0bc015459c393
Original-Signed-off-by: Yidi Lin <yidi.lin@mediatek.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/332712
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/14105
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/src/device/i2c.c b/src/device/i2c.c
new file mode 100644
index 0000000000..53bfdf0c94
--- /dev/null
+++ b/src/device/i2c.c
@@ -0,0 +1,46 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 MediaTek Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <device/i2c.h>
+
+int i2c_read_field(unsigned bus, uint8_t chip, uint8_t reg, uint8_t *data,
+		   uint8_t mask, uint8_t shift)
+{
+	int ret;
+	uint8_t buf = 0;
+
+	ret = i2c_readb(bus, chip, reg, &buf);
+
+	buf &= (mask << shift);
+	*data = (buf >> shift);
+
+	return ret;
+}
+
+int i2c_write_field(unsigned bus, uint8_t chip, uint8_t reg, uint8_t data,
+		    uint8_t mask, uint8_t shift)
+{
+	int ret;
+	uint8_t buf = 0;
+
+	ret = i2c_readb(bus, chip, reg, &buf);
+
+	buf &= ~(mask << shift);
+	buf |= (data << shift);
+
+	ret |= i2c_writeb(bus, chip, reg, buf);
+
+	return ret;
+}