linux-kernel - [PATCH v2 3/3] drm: bridge: anx7625: implement message sending

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Message-Id: <20260121-anx7625-typec-v2-3-d14f31256a17@oss.qualcomm.com>
Date: Wed, 21 Jan 2026 12:15:47 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, Xin Ji <xji@...logixsemi.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] drm: bridge: anx7625: implement message sending

Swapping the data role requires sending the message to the other USB-C
side. Implement sending these messages through the OCM. The code is
largely based on the anx7411.c USB-C driver.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/gpu/drm/bridge/analogix/anx7625.c | 68 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/bridge/analogix/anx7625.h | 12 ++++++
 2 files changed, 80 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
index 8dc6e3b16968..c43519097a45 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.c
+++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
@@ -1484,6 +1484,73 @@ static void anx7625_start_dp_work(struct anx7625_data *ctx)
 }
 
 #if IS_REACHABLE(CONFIG_TYPEC)
+static u8 anx7625_checksum(u8 *buf, u8 len)
+{
+	u8 ret = 0;
+	u8 i;
+
+	for (i = 0; i < len; i++)
+		ret += buf[i];
+
+	return ret;
+}
+
+static int anx7625_read_msg_ctrl_status(struct anx7625_data *ctx)
+{
+	return anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, CMD_SEND_BUF);
+}
+
+static int anx7625_wait_msg_empty(struct anx7625_data *ctx)
+{
+	int val;
+
+	return readx_poll_timeout(anx7625_read_msg_ctrl_status, ctx,
+				  val, (val < 0) || (val == 0),
+				  2000, 2000 * 150);
+}
+
+static int anx7625_send_msg(struct anx7625_data *ctx, u8 type, u8 *buf, u8 size)
+{
+	struct fw_msg *msg = &ctx->send_msg;
+	u8 crc;
+	int ret;
+
+	size = min_t(u8, size, (u8)MAX_BUF_LEN);
+	memcpy(msg->buf, buf, size);
+	msg->msg_type = type;
+
+	/* msg len equals buffer length + msg_type */
+	msg->msg_len = size + 1;
+
+	crc = anx7625_checksum((u8 *)msg, size + HEADER_LEN);
+	msg->buf[size] = 0 - crc;
+
+	ret = anx7625_wait_msg_empty(ctx);
+	if (ret)
+		return ret;
+
+	ret = anx7625_reg_block_write(ctx, ctx->i2c.rx_p0_client,
+				      CMD_SEND_BUF + 1, size + HEADER_LEN,
+				      &msg->msg_type);
+	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, CMD_SEND_BUF,
+				 msg->msg_len);
+	return ret;
+}
+
+static int anx7625_typec_dr_set(struct typec_port *port, enum typec_data_role role)
+{
+	struct anx7625_data *ctx = typec_get_drvdata(port);
+
+	if (role == ctx->typec_data_role)
+		return 0;
+
+	return anx7625_send_msg(ctx, 0x11, NULL, 0);
+}
+
+static const struct typec_operations anx7625_typec_ops = {
+	.dr_set = anx7625_typec_dr_set,
+};
+
 static void anx7625_typec_set_orientation(struct anx7625_data *ctx)
 {
 	u32 val = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, SYSTEM_STSTUS);
@@ -1542,6 +1609,7 @@ static int anx7625_typec_register(struct anx7625_data *ctx)
 	typec_cap.orientation_aware = true;
 
 	typec_cap.driver_data = ctx;
+	typec_cap.ops = &anx7625_typec_ops;
 
 	ctx->typec_port = typec_register_port(ctx->dev, &typec_cap);
 	if (IS_ERR(ctx->typec_port))
diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h
index a18561c213af..957d234ec07c 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.h
+++ b/drivers/gpu/drm/bridge/analogix/anx7625.h
@@ -67,6 +67,9 @@
 #define CC2_RA                  BIT(5)
 #define CC2_RP			(BIT(6) | BIT(7))
 
+#define CMD_SEND_BUF		0xC0
+#define CMD_RECV_BUF		0xE0
+
 /******** END of I2C Address 0x58 ********/
 
 /***************************************************************/
@@ -462,6 +465,14 @@ struct anx7625_i2c_client {
 struct typec_port;
 struct usb_role_switch;
 
+#define MAX_BUF_LEN	30
+struct fw_msg {
+	u8 msg_len;
+	u8 msg_type;
+	u8 buf[MAX_BUF_LEN];
+} __packed;
+#define HEADER_LEN		2
+
 struct anx7625_data {
 	struct anx7625_platform_data pdata;
 	struct platform_device *audio_pdev;
@@ -497,6 +508,7 @@ struct anx7625_data {
 	struct drm_connector *connector;
 	struct mipi_dsi_device *dsi;
 	struct drm_dp_aux aux;
+	struct fw_msg send_msg;
 };
 
 #endif  /* __ANX7625_H__ */

-- 
2.47.3