// SPDX-License-Identifier: GPL-2.0-only/* * framebuffer-coreboot.c * * Memory based framebuffer accessed through coreboot table. * * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com> * Copyright 2017 Google Inc. * Copyright 2017 Samuel Holland <samuel@sholland.org> */ #include <linux/device.h>#include <linux/kernel.h>#include <linux/mm.h>#include <linux/module.h>#include <linux/platform_data/simplefb.h>#include <linux/platform_device.h>#include <linux/sysfb.h> #include "coreboot_table.h" #define CB_TAG_FRAMEBUFFER 0x12 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS; static int framebuffer_probe(struct coreboot_device *dev){	int i;	u32 length;	struct lb_framebuffer *fb = &dev->framebuffer;	struct platform_device *pdev;	struct resource res;	struct simplefb_platform_data pdata = {		.width = fb->x_resolution,		.height = fb->y_resolution,		.stride = fb->bytes_per_line,		.format = NULL,	}; 	/*	 * On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry	 * in the coreboot table should only be used if the payload did	 * not pass a framebuffer information to the Linux kernel.	 *	 * If the global screen_info data has been filled, the Generic	 * System Framebuffers (sysfb) will already register a platform	 * device and pass that screen_info as platform_data to a driver	 * that can scan-out using the system provided framebuffer.	 */	if (sysfb_handles_screen_info())		return -ENODEV; 	if (!fb->physical_address)		return -ENODEV; 	for (i = 0; i < ARRAY_SIZE(formats); ++i) {		if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&		    fb->red_mask_pos       == formats[i].red.offset &&		    fb->red_mask_size      == formats[i].red.length &&		    fb->green_mask_pos     == formats[i].green.offset &&		    fb->green_mask_size    == formats[i].green.length &&		    fb->blue_mask_pos      == formats[i].blue.offset &&		    fb->blue_mask_size     == formats[i].blue.length)			pdata.format = formats[i].name;	}	if (!pdata.format)		return -ENODEV; 	memset(&res, 0, sizeof(res));	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;	res.name = "Coreboot Framebuffer";	res.start = fb->physical_address;	length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);	res.end = res.start + length - 1;	if (res.end <= res.start)		return -EINVAL; 	pdev = platform_device_register_resndata(&dev->dev,						 "simple-framebuffer", 0,						 &res, 1, &pdata,						 sizeof(pdata));	if (IS_ERR(pdev))		pr_warn("coreboot: could not register framebuffer\n");	else		dev_set_drvdata(&dev->dev, pdev); 	return PTR_ERR_OR_ZERO(pdev);} static void framebuffer_remove(struct coreboot_device *dev){	struct platform_device *pdev = dev_get_drvdata(&dev->dev); 	platform_device_unregister(pdev);} static const struct coreboot_device_id framebuffer_ids[] = {	{ .tag = CB_TAG_FRAMEBUFFER },	{ /* sentinel */ }};MODULE_DEVICE_TABLE(coreboot, framebuffer_ids); static struct coreboot_driver framebuffer_driver = {	.probe = framebuffer_probe,	.remove = framebuffer_remove,	.drv = {		.name = "framebuffer",	},	.id_table = framebuffer_ids,};module_coreboot_driver(framebuffer_driver); MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");MODULE_DESCRIPTION("Memory based framebuffer accessed through coreboot table");MODULE_LICENSE("GPL");