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
 23static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
 24
 25static 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	if (!fb->physical_address)
 40		return -ENODEV;
 41
 42	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
 43		if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&
 44		    fb->red_mask_pos       == formats[i].red.offset &&
 45		    fb->red_mask_size      == formats[i].red.length &&
 46		    fb->green_mask_pos     == formats[i].green.offset &&
 47		    fb->green_mask_size    == formats[i].green.length &&
 48		    fb->blue_mask_pos      == formats[i].blue.offset &&
 49		    fb->blue_mask_size     == formats[i].blue.length)
 50			pdata.format = formats[i].name;
 51	}
 52	if (!pdata.format)
 53		return -ENODEV;
 54
 55	memset(&res, 0, sizeof(res));
 56	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 57	res.name = "Coreboot Framebuffer";
 58	res.start = fb->physical_address;
 59	length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
 60	res.end = res.start + length - 1;
 61	if (res.end <= res.start)
 62		return -EINVAL;
 63
 64	pdev = platform_device_register_resndata(&dev->dev,
 65						 "simple-framebuffer", 0,
 66						 &res, 1, &pdata,
 67						 sizeof(pdata));
 68	if (IS_ERR(pdev))
 69		pr_warn("coreboot: could not register framebuffer\n");
 70	else
 71		dev_set_drvdata(&dev->dev, pdev);
 72
 73	return PTR_ERR_OR_ZERO(pdev);
 74}
 75
 76static void framebuffer_remove(struct coreboot_device *dev)
 77{
 78	struct platform_device *pdev = dev_get_drvdata(&dev->dev);
 79
 80	platform_device_unregister(pdev);
 81}
 82
 83static const struct coreboot_device_id framebuffer_ids[] = {
 84	{ .tag = CB_TAG_FRAMEBUFFER },
 85	{ /* sentinel */ }
 86};
 87MODULE_DEVICE_TABLE(coreboot, framebuffer_ids);
 88
 89static struct coreboot_driver framebuffer_driver = {
 90	.probe = framebuffer_probe,
 91	.remove = framebuffer_remove,
 92	.drv = {
 93		.name = "framebuffer",
 94	},
 95	.id_table = framebuffer_ids,
 96};
 97module_coreboot_driver(framebuffer_driver);
 98
 99MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
100MODULE_LICENSE("GPL");