tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 break;
55 }
56 }
57
58 of_node_put(root);
59
60 /*
61 * If there is a coretile HDLCD and it has a driver,
62 * do not mux the CLCD on the motherboard to the DVI.
63 */
64 if (has_coretile_hdlcd && IS_ENABLED(CONFIG_DRM_HDLCD))
65 mux_motherboard = false;
66
67 /*
68 * On the Vexpress CA9 we let the CLCD on the coretile
69 * take precedence, so also in this case do not mux the
70 * motherboard to the DVI.
71 */
72 if (has_coretile_clcd)
73 mux_motherboard = false;
74
75 if (mux_motherboard) {
76 dev_info(dev, "DVI muxed to motherboard CLCD\n");
77 val = VEXPRESS_FPGAMUX_MOTHERBOARD;
78 } else if (ct_clcd == dev->of_node) {
79 dev_info(dev,
80 "DVI muxed to daughterboard 1 (core tile) CLCD\n");
81 val = VEXPRESS_FPGAMUX_DAUGHTERBOARD_1;
82 } else {
83 dev_info(dev, "core tile graphics present\n");
84 dev_info(dev, "this device will be deactivated\n");
85 return -ENODEV;
86 }
87
88 ret = regmap_write(map, 0, val);
89 if (ret) {
90 dev_err(dev, "error setting DVI muxmode\n");
91 return -ENODEV;
92 }
93
94 return 0;
95}
96
97/*
98 * This sets up the regmap pointer that will then be retrieved by
99 * the detection code in pl111_versatile.c and passed in to the
100 * pl111_vexpress_clcd_init() function above.
101 */
102static int vexpress_muxfpga_probe(struct platform_device *pdev)
103{
104 struct device *dev = &pdev->dev;
105 struct regmap *map;
106
107 map = devm_regmap_init_vexpress_config(&pdev->dev);
108 if (IS_ERR(map))
109 return PTR_ERR(map);
110 dev_set_drvdata(dev, map);
111
112 return 0;
113}
114
115static const struct of_device_id vexpress_muxfpga_match[] = {
116 { .compatible = "arm,vexpress-muxfpga", },
117 {}
118};
119
120static struct platform_driver vexpress_muxfpga_driver = {
121 .driver = {
122 .name = "vexpress-muxfpga",
123 .of_match_table = of_match_ptr(vexpress_muxfpga_match),
124 },
125 .probe = vexpress_muxfpga_probe,
126};
127
128int vexpress_muxfpga_init(void)
129{
130 int ret;
131
132 ret = platform_driver_register(&vexpress_muxfpga_driver);
133 /* -EBUSY just means this driver is already registered */
134 if (ret == -EBUSY)
135 ret = 0;
136 return ret;
137}