[PATCH 2/3] usb: typec: fsa4480: Add support to swap SBU orientation

[Luca Weiss]

On some hardware designs the AUX+/- lanes are connected reversed to
SBU1/2 compared to the expected design by FSA4480.

Made more complicated, the otherwise compatible Orient-Chip OCP96011
expects the lanes to be connected reversed compared to FSA4480.

* FSA4480 block diagram shows AUX+ connected to SBU2 and AUX- to SBU1.
* OCP96011 block diagram shows AUX+ connected to SBU1 and AUX- to SBU2.

So if OCP96011 is used as drop-in for FSA4480 then the orientation
handling in the driver needs to be reversed to match the expectation of
the OCP96011 hardware.

Support parsing the data-lanes parameter in the endpoint node to swap
this in the driver.

The parse_data_lanes_mapping function is mostly taken from nb7vpq904m.c.

Signed-off-by: Luca Weiss <luca.weiss@xxxxxxxxxxxxx>
---
 drivers/usb/typec/mux/fsa4480.c | 81 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c
index e0ee1f621abb..6ee467c96fb6 100644
--- a/drivers/usb/typec/mux/fsa4480.c
+++ b/drivers/usb/typec/mux/fsa4480.c
@@ -9,6 +9,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/of_graph.h>
 #include <linux/regmap.h>
 #include <linux/usb/typec_dp.h>
 #include <linux/usb/typec_mux.h>
@@ -60,6 +61,7 @@ struct fsa4480 {
 	unsigned int svid;
 
 	u8 cur_enable;
+	bool swap_sbu_lanes;
 };
 
 static const struct regmap_config fsa4480_regmap_config = {
@@ -76,6 +78,9 @@ static int fsa4480_set(struct fsa4480 *fsa)
 	u8 enable = FSA4480_ENABLE_DEVICE;
 	u8 sel = 0;
 
+	if (fsa->swap_sbu_lanes)
+		reverse = !reverse;
+
 	/* USB Mode */
 	if (fsa->mode < TYPEC_STATE_MODAL ||
 	    (!fsa->svid && (fsa->mode == TYPEC_MODE_USB2 ||
@@ -179,12 +184,84 @@ static int fsa4480_mux_set(struct typec_mux_dev *mux, struct typec_mux_state *st
 	return ret;
 }
 
+enum {
+	NORMAL_LANE_MAPPING,
+	INVERT_LANE_MAPPING,
+};
+
+#define DATA_LANES_COUNT	2
+
+static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
+	[NORMAL_LANE_MAPPING] = { 0, 1 },
+	[INVERT_LANE_MAPPING] = { 1, 0 },
+};
+
+static int fsa4480_parse_data_lanes_mapping(struct fsa4480 *fsa)
+{
+	struct device_node *ep;
+	u32 data_lanes[DATA_LANES_COUNT];
+	int ret, i, j;
+
+	ep = of_graph_get_next_endpoint(fsa->client->dev.of_node, NULL);
+	if (!ep)
+		return 0;
+
+	ret = of_property_count_u32_elems(ep, "data-lanes");
+	if (ret == -EINVAL)
+		/* Property isn't here, consider default mapping */
+		goto out_done;
+	if (ret < 0)
+		goto out_error;
+
+	if (ret != DATA_LANES_COUNT) {
+		dev_err(&fsa->client->dev, "expected 2 data lanes\n");
+		ret = -EINVAL;
+		goto out_error;
+	}
+
+	ret = of_property_read_u32_array(ep, "data-lanes", data_lanes, DATA_LANES_COUNT);
+	if (ret)
+		goto out_error;
+
+	for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
+		for (j = 0; j < DATA_LANES_COUNT; j++) {
+			if (data_lanes[j] != supported_data_lane_mapping[i][j])
+				break;
+		}
+
+		if (j == DATA_LANES_COUNT)
+			break;
+	}
+
+	switch (i) {
+	case NORMAL_LANE_MAPPING:
+		break;
+	case INVERT_LANE_MAPPING:
+		fsa->swap_sbu_lanes = true;
+		dev_info(&fsa->client->dev, "using inverted data lanes mapping\n");
+		break;
+	default:
+		dev_err(&fsa->client->dev, "invalid data lanes mapping\n");
+		ret = -EINVAL;
+		goto out_error;
+	}
+
+out_done:
+	ret = 0;
+
+out_error:
+	of_node_put(ep);
+
+	return ret;
+}
+
 static int fsa4480_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct typec_switch_desc sw_desc = { };
 	struct typec_mux_desc mux_desc = { };
 	struct fsa4480 *fsa;
+	int ret;
 
 	fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);
 	if (!fsa)
@@ -193,6 +270,10 @@ static int fsa4480_probe(struct i2c_client *client)
 	fsa->client = client;
 	mutex_init(&fsa->lock);
 
+	ret = fsa4480_parse_data_lanes_mapping(fsa);
+	if (ret)
+		return ret;
+
 	fsa->regmap = devm_regmap_init_i2c(client, &fsa4480_regmap_config);
 	if (IS_ERR(fsa->regmap))
 		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");

-- 
2.42.0