[PATCH] drm/panel: sn65dsi86: Implement AUX channel

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This was hand-rolled in the first version, and will surely be useful as
we expand the driver to support more varied use cases.

Cc: Sandeep Panda <spanda@xxxxxxxxxxxxxx>
Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
---
 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 107 ++++++++++++++++++++++++--
 1 file changed, 100 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 1b6e8b72be58..50aa8c3c39fc 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -7,12 +7,14 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_dp_helper.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <linux/clk.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
+#include <linux/iopoll.h>
 #include <linux/of_graph.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
@@ -29,12 +31,15 @@
 #define SN_DATARATE_CONFIG_REG			0x94
 #define SN_PLL_ENABLE_REG			0x0D
 #define SN_SCRAMBLE_CONFIG_REG			0x95
-#define SN_AUX_WDATA0_REG			0x64
+#define SN_AUX_WDATA_REG(x)			(0x64 + x)
 #define SN_AUX_ADDR_19_16_REG			0x74
 #define SN_AUX_ADDR_15_8_REG			0x75
 #define SN_AUX_ADDR_7_0_REG			0x76
 #define SN_AUX_LENGTH_REG			0x77
 #define SN_AUX_CMD_REG				0x78
+#define  AUX_CMD_SEND				0x01
+#define  AUX_CMD_REQ(x)				(x << 4)
+#define SN_AUX_RDATA_REG(x)			(0x79 + x)
 #define SN_ML_TX_MODE_REG			0x96
 /* video config specific registers */
 #define SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG	0x20
@@ -64,6 +69,9 @@
 #define SN_DP_DATA_RATE_OFFSET	5
 #define SN_SYNC_POLARITY_OFFSET	7
 
+/* Matches DP_AUX_MAX_PAYLOAD_BYTES (for now) */
+#define SN_AUX_MAX_PAYLOAD_BYTES	16
+
 #define SN_ENABLE_VID_STREAM_BIT	BIT(3)
 #define SN_REFCLK_FREQ_BITS		GENMASK(3, 1)
 #define SN_DSIA_NUM_LANES_BITS		GENMASK(4, 3)
@@ -76,6 +84,7 @@
 struct ti_sn_bridge {
 	struct device			*dev;
 	struct regmap			*regmap;
+	struct drm_dp_aux		aux;
 	struct drm_bridge		bridge;
 	struct drm_connector		connector;
 	struct device_node		*host_node;
@@ -473,12 +482,7 @@ static void ti_sn_bridge_enable(struct drm_bridge *bridge)
 	 * authentication method. We need to enable this method in the eDP panel
 	 * at DisplayPort address 0x0010A prior to link training.
 	 */
-	regmap_write(pdata->regmap, SN_AUX_WDATA0_REG, 0x01);
-	regmap_write(pdata->regmap, SN_AUX_ADDR_19_16_REG, 0x00);
-	regmap_write(pdata->regmap, SN_AUX_ADDR_15_8_REG, 0x01);
-	regmap_write(pdata->regmap, SN_AUX_ADDR_7_0_REG, 0x0A);
-	regmap_write(pdata->regmap, SN_AUX_LENGTH_REG, 0x01);
-	regmap_write(pdata->regmap, SN_AUX_CMD_REG, 0x81);
+	drm_dp_dpcd_writeb(&pdata->aux, DP_EDP_CONFIGURATION_SET, 0);
 	usleep_range(10000, 10500); /* 10ms delay recommended by spec */
 
 	/* Semi auto link training mode */
@@ -527,6 +531,90 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
 	.post_disable = ti_sn_bridge_post_disable,
 };
 
+static struct ti_sn_bridge *aux_to_ti_sn_bridge(struct drm_dp_aux *aux)
+{
+	return container_of(aux, struct ti_sn_bridge, aux);
+}
+
+static bool ti_sn_cmd_done(struct ti_sn_bridge *pdata)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(pdata->regmap, SN_AUX_CMD_REG, &val);
+	WARN_ON(ret);
+	return ret || !(val & AUX_CMD_SEND);
+}
+
+static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux,
+				  struct drm_dp_aux_msg *msg)
+{
+	struct ti_sn_bridge *pdata = aux_to_ti_sn_bridge(aux);
+	u32 request = msg->request & ~DP_AUX_I2C_MOT;
+	u32 request_val = AUX_CMD_REQ(msg->request);
+	u8 *buf = (u8 *)msg->buffer;
+	bool cmd_done;
+	int ret, i;
+
+	if (msg->size > SN_AUX_MAX_PAYLOAD_BYTES)
+		return -EINVAL;
+
+	switch (request) {
+	case DP_AUX_NATIVE_WRITE:
+	case DP_AUX_I2C_WRITE:
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ:
+		regmap_write(pdata->regmap, SN_AUX_CMD_REG, request_val);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap_write(pdata->regmap, SN_AUX_ADDR_19_16_REG,
+		     (msg->address >> 16) & 0xFF);
+	regmap_write(pdata->regmap, SN_AUX_ADDR_15_8_REG,
+		     (msg->address >> 8) & 0xFF);
+	regmap_write(pdata->regmap, SN_AUX_ADDR_7_0_REG, msg->address & 0xFF);
+
+	regmap_write(pdata->regmap, SN_AUX_LENGTH_REG, msg->size);
+
+	if (request == DP_AUX_NATIVE_WRITE || request == DP_AUX_I2C_WRITE) {
+		for (i = 0; i < msg->size; i++)
+			regmap_write(pdata->regmap, SN_AUX_WDATA_REG(i),
+				     buf[i]);
+	}
+
+	regmap_write(pdata->regmap, SN_AUX_CMD_REG, request_val | AUX_CMD_SEND);
+
+	ret = readx_poll_timeout(ti_sn_cmd_done, pdata, cmd_done, cmd_done,
+				 200, 50 * 1000);
+	if (ret)
+		return ret;
+
+	if (request == DP_AUX_NATIVE_READ || request == DP_AUX_I2C_READ) {
+		unsigned int val;
+
+		ret = regmap_read(pdata->regmap, SN_AUX_LENGTH_REG, &val);
+		if (ret)
+			return ret;
+		else if (val != msg->size)
+			return -ENXIO;
+
+		for (i = 0; i < msg->size; i++) {
+			unsigned int val;
+			ret = regmap_read(pdata->regmap, SN_AUX_RDATA_REG(i),
+					  &val);
+			if (ret)
+				return ret;
+
+			WARN_ON(val & ~0xFF);
+			buf[i] = (u8)(val & 0xFF);
+		}
+	}
+
+	return msg->size;
+}
+
 static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
 {
 	struct device_node *np = pdata->dev->of_node;
@@ -606,6 +694,11 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
 
 	i2c_set_clientdata(client, pdata);
 
+	pdata->aux.name = "ti-sn65dsi86-aux";
+	pdata->aux.dev = pdata->dev;
+	pdata->aux.transfer = ti_sn_aux_transfer;
+	drm_dp_aux_register(&pdata->aux);
+
 	pdata->bridge.funcs = &ti_sn_bridge_funcs;
 	pdata->bridge.of_node = client->dev.of_node;
 
-- 
Sean Paul, Software Engineer, Google / Chromium OS

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