1 /*
2  * framebuffer-coreboot.c
3  *
4  * Memory based framebuffer accessed through coreboot table.
5  *
6  * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com>
7  * Copyright 2017 Google Inc.
8  * Copyright 2017 Samuel Holland <samuel@sholland.org>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License v2.0 as published by
12  * the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  * GNU General Public License for more details.
18  */
19 
20 #include <linux/device.h>
21 #include <linux/kernel.h>
22 #include <linux/mm.h>
23 #include <linux/module.h>
24 #include <linux/platform_data/simplefb.h>
25 #include <linux/platform_device.h>
26 
27 #include "coreboot_table.h"
28 
29 #define CB_TAG_FRAMEBUFFER 0x12
30 
31 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
32 
33 static int framebuffer_probe(struct coreboot_device *dev)
34 {
35 	int i;
36 	u32 length;
37 	struct lb_framebuffer *fb = &dev->framebuffer;
38 	struct platform_device *pdev;
39 	struct resource res;
40 	struct simplefb_platform_data pdata = {
41 		.width = fb->x_resolution,
42 		.height = fb->y_resolution,
43 		.stride = fb->bytes_per_line,
44 		.format = NULL,
45 	};
46 
47 	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
48 		if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&
49 		    fb->red_mask_pos       == formats[i].red.offset &&
50 		    fb->red_mask_size      == formats[i].red.length &&
51 		    fb->green_mask_pos     == formats[i].green.offset &&
52 		    fb->green_mask_size    == formats[i].green.length &&
53 		    fb->blue_mask_pos      == formats[i].blue.offset &&
54 		    fb->blue_mask_size     == formats[i].blue.length &&
55 		    fb->reserved_mask_pos  == formats[i].transp.offset &&
56 		    fb->reserved_mask_size == formats[i].transp.length)
57 			pdata.format = formats[i].name;
58 	}
59 	if (!pdata.format)
60 		return -ENODEV;
61 
62 	memset(&res, 0, sizeof(res));
63 	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
64 	res.name = "Coreboot Framebuffer";
65 	res.start = fb->physical_address;
66 	length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
67 	res.end = res.start + length - 1;
68 	if (res.end <= res.start)
69 		return -EINVAL;
70 
71 	pdev = platform_device_register_resndata(&dev->dev,
72 						 "simple-framebuffer", 0,
73 						 &res, 1, &pdata,
74 						 sizeof(pdata));
75 	if (IS_ERR(pdev))
76 		pr_warn("coreboot: could not register framebuffer\n");
77 	else
78 		dev_set_drvdata(&dev->dev, pdev);
79 
80 	return PTR_ERR_OR_ZERO(pdev);
81 }
82 
83 static int framebuffer_remove(struct coreboot_device *dev)
84 {
85 	struct platform_device *pdev = dev_get_drvdata(&dev->dev);
86 
87 	platform_device_unregister(pdev);
88 
89 	return 0;
90 }
91 
92 static struct coreboot_driver framebuffer_driver = {
93 	.probe = framebuffer_probe,
94 	.remove = framebuffer_remove,
95 	.drv = {
96 		.name = "framebuffer",
97 	},
98 	.tag = CB_TAG_FRAMEBUFFER,
99 };
100 
101 static int __init coreboot_framebuffer_init(void)
102 {
103 	return coreboot_driver_register(&framebuffer_driver);
104 }
105 
106 static void coreboot_framebuffer_exit(void)
107 {
108 	coreboot_driver_unregister(&framebuffer_driver);
109 }
110 
111 module_init(coreboot_framebuffer_init);
112 module_exit(coreboot_framebuffer_exit);
113 
114 MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
115 MODULE_LICENSE("GPL");
116