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
pl111_vexpress_clcd_init(struct device * dev,struct pl111_drm_dev_private * priv,struct regmap * map)25 int 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 */
vexpress_muxfpga_probe(struct platform_device * pdev)103 static 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
116 static const struct of_device_id vexpress_muxfpga_match[] = {
117 { .compatible = "arm,vexpress-muxfpga", },
118 {}
119 };
120
121 static 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
vexpress_muxfpga_init(void)129 int 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 }
139