1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2016 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  4 */
  5
  6#include <linux/gpio/consumer.h>
  7#include <linux/module.h>
  8#include <linux/of.h>
  9#include <linux/of_graph.h>
 10#include <linux/platform_device.h>
 11
 12#include <drm/drm_bridge.h>
 13#include <drm/drm_panel.h>
 14
 15struct lvds_encoder {
 16	struct drm_bridge bridge;
 17	struct drm_bridge *panel_bridge;
 18	struct gpio_desc *powerdown_gpio;
 19};
 20
 21static int lvds_encoder_attach(struct drm_bridge *bridge)
 22{
 23	struct lvds_encoder *lvds_encoder = container_of(bridge,
 24							 struct lvds_encoder,
 25							 bridge);
 26
 27	return drm_bridge_attach(bridge->encoder, lvds_encoder->panel_bridge,
 28				 bridge);
 29}
 30
 31static void lvds_encoder_enable(struct drm_bridge *bridge)
 32{
 33	struct lvds_encoder *lvds_encoder = container_of(bridge,
 34							 struct lvds_encoder,
 35							 bridge);
 36
 37	if (lvds_encoder->powerdown_gpio)
 38		gpiod_set_value_cansleep(lvds_encoder->powerdown_gpio, 0);
 39}
 40
 41static void lvds_encoder_disable(struct drm_bridge *bridge)
 42{
 43	struct lvds_encoder *lvds_encoder = container_of(bridge,
 44							 struct lvds_encoder,
 45							 bridge);
 46
 47	if (lvds_encoder->powerdown_gpio)
 48		gpiod_set_value_cansleep(lvds_encoder->powerdown_gpio, 1);
 49}
 50
 51static struct drm_bridge_funcs funcs = {
 52	.attach = lvds_encoder_attach,
 53	.enable = lvds_encoder_enable,
 54	.disable = lvds_encoder_disable,
 55};
 56
 57static int lvds_encoder_probe(struct platform_device *pdev)
 58{
 59	struct device *dev = &pdev->dev;
 60	struct device_node *port;
 61	struct device_node *endpoint;
 62	struct device_node *panel_node;
 63	struct drm_panel *panel;
 64	struct lvds_encoder *lvds_encoder;
 65
 66	lvds_encoder = devm_kzalloc(dev, sizeof(*lvds_encoder), GFP_KERNEL);
 67	if (!lvds_encoder)
 68		return -ENOMEM;
 69
 70	lvds_encoder->powerdown_gpio = devm_gpiod_get_optional(dev, "powerdown",
 71							       GPIOD_OUT_HIGH);
 72	if (IS_ERR(lvds_encoder->powerdown_gpio)) {
 73		int err = PTR_ERR(lvds_encoder->powerdown_gpio);
 74
 75		if (err != -EPROBE_DEFER)
 76			dev_err(dev, "powerdown GPIO failure: %d\n", err);
 77		return err;
 78	}
 79
 80	/* Locate the panel DT node. */
 81	port = of_graph_get_port_by_id(dev->of_node, 1);
 82	if (!port) {
 83		dev_dbg(dev, "port 1 not found\n");
 84		return -ENXIO;
 85	}
 86
 87	endpoint = of_get_child_by_name(port, "endpoint");
 88	of_node_put(port);
 89	if (!endpoint) {
 90		dev_dbg(dev, "no endpoint for port 1\n");
 91		return -ENXIO;
 92	}
 93
 94	panel_node = of_graph_get_remote_port_parent(endpoint);
 95	of_node_put(endpoint);
 96	if (!panel_node) {
 97		dev_dbg(dev, "no remote endpoint for port 1\n");
 98		return -ENXIO;
 99	}
100
101	panel = of_drm_find_panel(panel_node);
102	of_node_put(panel_node);
103	if (IS_ERR(panel)) {
104		dev_dbg(dev, "panel not found, deferring probe\n");
105		return PTR_ERR(panel);
106	}
107
108	lvds_encoder->panel_bridge =
109		devm_drm_panel_bridge_add(dev, panel, DRM_MODE_CONNECTOR_LVDS);
110	if (IS_ERR(lvds_encoder->panel_bridge))
111		return PTR_ERR(lvds_encoder->panel_bridge);
112
113	/* The panel_bridge bridge is attached to the panel's of_node,
114	 * but we need a bridge attached to our of_node for our user
115	 * to look up.
116	 */
117	lvds_encoder->bridge.of_node = dev->of_node;
118	lvds_encoder->bridge.funcs = &funcs;
119	drm_bridge_add(&lvds_encoder->bridge);
120
121	platform_set_drvdata(pdev, lvds_encoder);
122
123	return 0;
124}
125
126static int lvds_encoder_remove(struct platform_device *pdev)
127{
128	struct lvds_encoder *lvds_encoder = platform_get_drvdata(pdev);
129
130	drm_bridge_remove(&lvds_encoder->bridge);
131
132	return 0;
133}
134
135static const struct of_device_id lvds_encoder_match[] = {
136	{ .compatible = "lvds-encoder" },
137	{ .compatible = "thine,thc63lvdm83d" },
138	{},
139};
140MODULE_DEVICE_TABLE(of, lvds_encoder_match);
141
142static struct platform_driver lvds_encoder_driver = {
143	.probe	= lvds_encoder_probe,
144	.remove	= lvds_encoder_remove,
145	.driver		= {
146		.name		= "lvds-encoder",
147		.of_match_table	= lvds_encoder_match,
148	},
149};
150module_platform_driver(lvds_encoder_driver);
151
152MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
153MODULE_DESCRIPTION("Transparent parallel to LVDS encoder");
154MODULE_LICENSE("GPL");