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_bridge.h

@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2019-2021, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifndef _DP_AUX_BRIDGE_H_
+#define _DP_AUX_BRIDGE_H_
+
+#include <linux/types.h>
+#include <drm/drm_dp_helper.h>
+
+/**
+ * enum dp_aux_bridge_flag - DP aux bridge capability flag
+ * DP_AUX_BRIDGE_HPD: HPD will be generated by DP aux bridge
+ * DP_AUX_BRIDGE_MST: MST simulator is used by DP aux bridge
+ */
+enum dp_aux_bridge_flag {
+	DP_AUX_BRIDGE_HPD = (1 << 0),
+	DP_AUX_BRIDGE_MST = (1 << 1),
+};
+
+/**
+ * struct dp_aux_bridge - DP aux bridge control structure
+ * @of_node: device node pointer to the bridge
+ * @dev_priv: pointer to the bridge driver's internal context
+ * @flag: flag for capability
+ * @mst_ctx: pointer to mst context when DP_AUX_BRIDGE_MST is set
+ * @head: to keep track of all added bridges
+ */
+struct dp_aux_bridge {
+#ifdef CONFIG_OF
+	struct device_node *of_node;
+#endif
+	void *dev_priv;
+	u32 flag;
+	void *mst_ctx;
+	struct list_head head;
+
+	/**
+	 * @register_hpd:
+	 *
+	 * This callback is invoked whenever bridge is registered
+	 * for HPD handling
+	 *
+	 * The attach callback is optional.
+	 *
+	 * Host will pass HPD callback handle to bridge, with
+	 * arguments @hpd_cb(void* dev, bool hpd, bool hpd_irq):
+	 *
+	 *     @dev: private handle passed in register_hpd
+	 *     @hpd: true if HPD is high, false if HPD is low
+	 *     @hpd_irq: true if this is a HPD irq. @hpd will be
+	 *     ignored when hpd_irq is true.
+	 *
+	 * RETURNS:
+	 *
+	 * Zero on success, error code on failure.
+	 */
+	int (*register_hpd)(struct dp_aux_bridge *bridge,
+			int (*hpd_cb)(void *, bool, bool), void *dev);
+
+	/**
+	 * @transfer:
+	 *
+	 * This callback is invoked whenever dp_aux transfer
+	 * is called from host. Inside @transfer bridge can still
+	 * call @drm_aux->transfer to trigger the actual
+	 * DPCD/I2C transfer at host side.
+	 *
+	 * The attach callback is optional.
+	 *
+	 * RETURNS:
+	 *
+	 * Size of the bytes transferred, error code on failure.
+	 */
+	ssize_t (*transfer)(struct dp_aux_bridge *bridge,
+			struct drm_dp_aux *drm_aux,
+			struct drm_dp_aux_msg *msg);
+};
+
+/**
+ * dp_aux_add_bridge - Register DP aux bridge
+ * @bridge: bridge pointer
+ * return: 0 if successful
+ */
+int dp_aux_add_bridge(struct dp_aux_bridge *bridge);
+
+#ifdef CONFIG_OF
+/**
+ * of_dp_aux_find_bridge - Find registered DP aux bridge
+ * @np: device node pointer to the bridge
+ * return: DP aux bridge pointer, NULL if not found
+ */
+struct dp_aux_bridge *of_dp_aux_find_bridge(struct device_node *np);
+#endif
+
+#endif /* _DP_AUX_BRIDGE_H_ */
+