TDP142: Initial driver

Initial driver for the TDP142, a DisplayPort redriver chip.  The initial
implementation simply provides access to the chip's control selection
since it must be explicitly enabled after the chip powers on.

BRANCH=None
BUG=b:187856682
TEST=make -j buildall

Signed-off-by: Diana Z <dzigterman@chromium.org>
Change-Id: I4afe4b0453ef49154b766166f608bd3d0fb8848f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2915823
Reviewed-by: Rob Barnes <robbarnes@google.com>

3 files changed, 83 insertions, 0 deletions

diff --git a/driver/build.mk b/driver/build.mk
index 72bbd46a89..93536b76f7 100644
--- a/driver/build.mk
+++ b/driver/build.mk
@@ -75,6 +75,9 @@ driver-$(CONFIG_CHARGER_RT9467)+=charger/rt946x.o
 driver-$(CONFIG_CHARGER_SY21612)+=charger/sy21612.o
 driver-$(CONFIG_CHARGER_SM5803)+=charger/sm5803.o
 
+# DP Redrivers
+driver-$(CONFIG_DP_REDRIVER_TDP142)+=retimer/tdp142.o
+
 # Fingerprint Sensors
 include $(_driver_cur_dir)fingerprint/build.mk
 
diff --git a/driver/retimer/tdp142.c b/driver/retimer/tdp142.c
new file mode 100644
index 0000000000..e1632150d0
--- /dev/null
+++ b/driver/retimer/tdp142.c
@@ -0,0 +1,42 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Texas Instruments TDP142 DisplayPort Linear Redriver
+ */
+
+#include "common.h"
+#include "ec_commands.h"
+#include "i2c.h"
+#include "tdp142.h"
+
+static enum ec_error_list tdp142_write(int offset, int data)
+{
+	return i2c_write8(TDP142_I2C_PORT,
+			  TDP142_I2C_ADDR,
+			  offset, data);
+
+}
+
+static enum ec_error_list tdp142_read(int offset, int *regval)
+{
+	return i2c_read8(TDP142_I2C_PORT,
+			 TDP142_I2C_ADDR,
+			 offset, regval);
+
+}
+
+enum ec_error_list tdp142_set_ctlsel(enum tdp142_ctlsel selection)
+{
+	int regval;
+	enum ec_error_list rv;
+
+	rv = tdp142_read(TDP142_REG_GENERAL, &regval);
+	if (rv)
+		return rv;
+
+	regval &= ~TDP142_GENERAL_CTLSEL;
+	regval |= selection;
+
+	return tdp142_write(TDP142_REG_GENERAL, regval);
+}
diff --git a/driver/retimer/tdp142.h b/driver/retimer/tdp142.h
new file mode 100644
index 0000000000..8346a233a5
--- /dev/null
+++ b/driver/retimer/tdp142.h
@@ -0,0 +1,38 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Texas Instruments TDP142 DisplayPort Linear Redriver
+ */
+
+#ifndef __CROS_EC_REDRIVER_TDP142_H
+#define __CROS_EC_REDRIVER_TDP142_H
+
+#include "compile_time_macros.h"
+
+/*
+ * Note: Since DP redrivers do not have a standard EC structure, define a
+ * TDP142_I2C_PORT and TDP142_I2C_ADDR in board.h
+ */
+#define TDP142_I2C_ADDR0 0x44
+#define TDP142_I2C_ADDR1 0x47
+#define TDP142_I2C_ADDR2 0x0C
+#define TDP142_I2C_ADDR3 0x0F
+
+/* Registers */
+#define TDP142_REG_GENERAL		0x0A
+#define TDP142_GENERAL_CTLSEL		GENMASK(1, 0)
+#define TDP142_GENERAL_HPDIN_OVRRIDE	BIT(3)
+#define TDP142_GENERAL_EQ_OVERRIDE	BIT(4)
+#define TDP142_GENERAL_SWAP_HPDIN	BIT(5)
+
+enum tdp142_ctlsel {
+	TDP142_CTLSEL_SHUTDOWN,
+	TDP142_CTLSEL_DISABLED,
+	TDP142_CTLSEL_ENABLED,
+};
+
+/* Control redriver enable */
+enum ec_error_list tdp142_set_ctlsel(enum tdp142_ctlsel selection);
+
+#endif /* __CROS_EC_REDRIVER_TDP142_H */