disp: msm: dp: add dp aux bridge framework support

Create the framework to support external dp aux bridge device which
can handle DPCD/I2C/HPD from external.

Change-Id: Iabd0998efc8bf7134d186b1751d219c00217385c
Signed-off-by: Xiaowen Wu <wxiaowen@codeaurora.org>
Signed-off-by: Karim Henain <khenain@codeaurora.org>
Signed-off-by: Sudarsan Ramesh <sudarame@codeaurora.org>

msm/dp/dp_aux.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2012-2020, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2021, The Linux Foundation. All rights reserved.
  */
 
 #include <linux/soc/qcom/fsa4480-i2c.h>
@@ -26,6 +26,9 @@ struct dp_aux_private {
 	struct completion comp;
 	struct drm_dp_aux drm_aux;
 
+	struct dp_aux_bridge *aux_bridge;
+	bool bridge_in_transfer;
+
 	bool cmd_busy;
 	bool native;
 	bool read;
@@ -623,6 +626,25 @@ unlock_exit:
 	return ret;
 }
 
+static ssize_t dp_aux_bridge_transfer(struct drm_dp_aux *drm_aux,
+		struct drm_dp_aux_msg *msg)
+{
+	struct dp_aux_private *aux = container_of(drm_aux,
+			struct dp_aux_private, drm_aux);
+	ssize_t size;
+
+	if (aux->bridge_in_transfer) {
+		size = dp_aux_transfer(drm_aux, msg);
+	} else {
+		aux->bridge_in_transfer = true;
+		size = aux->aux_bridge->transfer(aux->aux_bridge,
+				drm_aux, msg);
+		aux->bridge_in_transfer = false;
+	}
+
+	return size;
+}
+
 static void dp_aux_reset_phy_config_indices(struct dp_aux_cfg *aux_cfg)
 {
 	int i = 0;
@@ -696,6 +718,10 @@ static int dp_aux_register(struct dp_aux *dp_aux)
 		goto exit;
 	}
 	dp_aux->drm_aux = &aux->drm_aux;
+
+	/* if bridge is defined, override transfer function */
+	if (aux->aux_bridge && aux->aux_bridge->transfer)
+		aux->drm_aux.transfer = dp_aux_bridge_transfer;
 exit:
 	return ret;
 }
@@ -749,6 +775,8 @@ static void dp_aux_set_sim_mode(struct dp_aux *dp_aux, bool en,
 	if (en) {
 		atomic_set(&aux->aborted, 0);
 		aux->drm_aux.transfer = dp_aux_transfer_debug;
+	} else if (aux->aux_bridge && aux->aux_bridge->transfer) {
+		aux->drm_aux.transfer = dp_aux_bridge_transfer;
 	} else {
 		aux->drm_aux.transfer = dp_aux_transfer;
 	}
@@ -803,7 +831,8 @@ end:
 }
 
 struct dp_aux *dp_aux_get(struct device *dev, struct dp_catalog_aux *catalog,
-		struct dp_parser *parser, struct device_node *aux_switch)
+		struct dp_parser *parser, struct device_node *aux_switch,
+		struct dp_aux_bridge *aux_bridge)
 {
 	int rc = 0;
 	struct dp_aux_private *aux;
@@ -832,6 +861,7 @@ struct dp_aux *dp_aux_get(struct device *dev, struct dp_catalog_aux *catalog,
 	aux->catalog = catalog;
 	aux->cfg = parser->aux_cfg;
 	aux->aux_switch_node = aux_switch;
+	aux->aux_bridge = aux_bridge;
 	dp_aux = &aux->dp_aux;
 	aux->retry_cnt = 0;
 	aux->dp_aux.reg = 0xFFFF;