1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * framebuffer-coreboot.c
4  *
5  * Memory based framebuffer accessed through coreboot table.
6  *
7  * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com>
8  * Copyright 2017 Google Inc.
9  * Copyright 2017 Samuel Holland <samuel@sholland.org>
10  */
11 
12 #include <linux/device.h>
13 #include <linux/kernel.h>
14 #include <linux/mm.h>
15 #include <linux/module.h>
16 #include <linux/platform_data/simplefb.h>
17 #include <linux/platform_device.h>
18 
19 #include "coreboot_table.h"
20 
21 #define CB_TAG_FRAMEBUFFER 0x12
22 
23 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
24 
framebuffer_probe(struct coreboot_device * dev)25 static int framebuffer_probe(struct coreboot_device *dev)
26 {
27 	int i;
28 	u32 length;
29 	struct lb_framebuffer *fb = &dev->framebuffer;
30 	struct platform_device *pdev;
31 	struct resource res;
32 	struct simplefb_platform_data pdata = {
33 		.width = fb->x_resolution,
34 		.height = fb->y_resolution,
35 		.stride = fb->bytes_per_line,
36 		.format = NULL,
37 	};
38 
39 	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
40 		if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&
41 		    fb->red_mask_pos       == formats[i].red.offset &&
42 		    fb->red_mask_size      == formats[i].red.length &&
43 		    fb->green_mask_pos     == formats[i].green.offset &&
44 		    fb->green_mask_size    == formats[i].green.length &&
45 		    fb->blue_mask_pos      == formats[i].blue.offset &&
46 		    fb->blue_mask_size     == formats[i].blue.length)
47 			pdata.format = formats[i].name;
48 	}
49 	if (!pdata.format)
50 		return -ENODEV;
51 
52 	memset(&res, 0, sizeof(res));
53 	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
54 	res.name = "Coreboot Framebuffer";
55 	res.start = fb->physical_address;
56 	length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
57 	res.end = res.start + length - 1;
58 	if (res.end <= res.start)
59 		return -EINVAL;
60 
61 	pdev = platform_device_register_resndata(&dev->dev,
62 						 "simple-framebuffer", 0,
63 						 &res, 1, &pdata,
64 						 sizeof(pdata));
65 	if (IS_ERR(pdev))
66 		pr_warn("coreboot: could not register framebuffer\n");
67 	else
68 		dev_set_drvdata(&dev->dev, pdev);
69 
70 	return PTR_ERR_OR_ZERO(pdev);
71 }
72 
framebuffer_remove(struct coreboot_device * dev)73 static void framebuffer_remove(struct coreboot_device *dev)
74 {
75 	struct platform_device *pdev = dev_get_drvdata(&dev->dev);
76 
77 	platform_device_unregister(pdev);
78 }
79 
80 static struct coreboot_driver framebuffer_driver = {
81 	.probe = framebuffer_probe,
82 	.remove = framebuffer_remove,
83 	.drv = {
84 		.name = "framebuffer",
85 	},
86 	.tag = CB_TAG_FRAMEBUFFER,
87 };
88 module_coreboot_driver(framebuffer_driver);
89 
90 MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
91 MODULE_LICENSE("GPL");
92