1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Versatile Express PL111 handling
  4 * Copyright (C) 2018 Linus Walleij
  5 *
  6 * This module binds to the "arm,vexpress-muxfpga" device on the
  7 * Versatile Express configuration bus and sets up which CLCD instance
  8 * gets muxed out on the DVI bridge.
  9 */
 10#include <linux/device.h>
 11#include <linux/module.h>
 12#include <linux/regmap.h>
 13#include <linux/vexpress.h>
 14#include <linux/platform_device.h>
 15#include <linux/of.h>
 16#include <linux/of_address.h>
 17#include <linux/of_platform.h>
 18#include "pl111_drm.h"
 19#include "pl111_vexpress.h"
 20
 21#define VEXPRESS_FPGAMUX_MOTHERBOARD		0x00
 22#define VEXPRESS_FPGAMUX_DAUGHTERBOARD_1	0x01
 23#define VEXPRESS_FPGAMUX_DAUGHTERBOARD_2	0x02
 24
 25int pl111_vexpress_clcd_init(struct device *dev,
 26			     struct pl111_drm_dev_private *priv,
 27			     struct regmap *map)
 28{
 29	struct device_node *root;
 30	struct device_node *child;
 31	struct device_node *ct_clcd = NULL;
 32	bool has_coretile_clcd = false;
 33	bool has_coretile_hdlcd = false;
 34	bool mux_motherboard = true;
 35	u32 val;
 36	int ret;
 37
 38	/*
 39	 * Check if we have a CLCD or HDLCD on the core tile by checking if a
 40	 * CLCD or HDLCD is available in the root of the device tree.
 41	 */
 42	root = of_find_node_by_path("/");
 43	if (!root)
 44		return -EINVAL;
 45
 46	for_each_available_child_of_node(root, child) {
 47		if (of_device_is_compatible(child, "arm,pl111")) {
 48			has_coretile_clcd = true;
 49			ct_clcd = child;
 50			break;
 51		}
 52		if (of_device_is_compatible(child, "arm,hdlcd")) {
 53			has_coretile_hdlcd = true;
 54			of_node_put(child);
 55			break;
 56		}
 57	}
 58
 59	of_node_put(root);
 60
 61	/*
 62	 * If there is a coretile HDLCD and it has a driver,
 63	 * do not mux the CLCD on the motherboard to the DVI.
 64	 */
 65	if (has_coretile_hdlcd && IS_ENABLED(CONFIG_DRM_HDLCD))
 66		mux_motherboard = false;
 67
 68	/*
 69	 * On the Vexpress CA9 we let the CLCD on the coretile
 70	 * take precedence, so also in this case do not mux the
 71	 * motherboard to the DVI.
 72	 */
 73	if (has_coretile_clcd)
 74		mux_motherboard = false;
 75
 76	if (mux_motherboard) {
 77		dev_info(dev, "DVI muxed to motherboard CLCD\n");
 78		val = VEXPRESS_FPGAMUX_MOTHERBOARD;
 79	} else if (ct_clcd == dev->of_node) {
 80		dev_info(dev,
 81			 "DVI muxed to daughterboard 1 (core tile) CLCD\n");
 82		val = VEXPRESS_FPGAMUX_DAUGHTERBOARD_1;
 83	} else {
 84		dev_info(dev, "core tile graphics present\n");
 85		dev_info(dev, "this device will be deactivated\n");
 86		return -ENODEV;
 87	}
 88
 89	ret = regmap_write(map, 0, val);
 90	if (ret) {
 91		dev_err(dev, "error setting DVI muxmode\n");
 92		return -ENODEV;
 93	}
 94
 95	return 0;
 96}
 97
 98/*
 99 * This sets up the regmap pointer that will then be retrieved by
100 * the detection code in pl111_versatile.c and passed in to the
101 * pl111_vexpress_clcd_init() function above.
102 */
103static int vexpress_muxfpga_probe(struct platform_device *pdev)
104{
105	struct device *dev = &pdev->dev;
106	struct regmap *map;
107
108	map = devm_regmap_init_vexpress_config(&pdev->dev);
109	if (IS_ERR(map))
110		return PTR_ERR(map);
111	dev_set_drvdata(dev, map);
112
113	return 0;
114}
115
116static const struct of_device_id vexpress_muxfpga_match[] = {
117	{ .compatible = "arm,vexpress-muxfpga", },
118	{}
119};
120
121static struct platform_driver vexpress_muxfpga_driver = {
122	.driver = {
123		.name = "vexpress-muxfpga",
124		.of_match_table = of_match_ptr(vexpress_muxfpga_match),
125	},
126	.probe = vexpress_muxfpga_probe,
127};
128
129int vexpress_muxfpga_init(void)
130{
131	int ret;
132
133	ret = platform_driver_register(&vexpress_muxfpga_driver);
134	/* -EBUSY just means this driver is already registered */
135	if (ret == -EBUSY)
136		ret = 0;
137	return ret;
138}