cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sysfb_simplefb.c (3670B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Generic System Framebuffers
      4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
      5 */
      6
      7/*
      8 * simple-framebuffer probing
      9 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
     10 * If the mode is incompatible, we return "false" and let the caller create
     11 * legacy nodes instead.
     12 */
     13
     14#include <linux/err.h>
     15#include <linux/init.h>
     16#include <linux/kernel.h>
     17#include <linux/mm.h>
     18#include <linux/platform_data/simplefb.h>
     19#include <linux/platform_device.h>
     20#include <linux/screen_info.h>
     21#include <linux/sysfb.h>
     22
     23static const char simplefb_resname[] = "BOOTFB";
     24static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
     25
     26/* try parsing screen_info into a simple-framebuffer mode struct */
     27__init bool sysfb_parse_mode(const struct screen_info *si,
     28			     struct simplefb_platform_data *mode)
     29{
     30	const struct simplefb_format *f;
     31	__u8 type;
     32	unsigned int i;
     33
     34	type = si->orig_video_isVGA;
     35	if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
     36		return false;
     37
     38	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
     39		f = &formats[i];
     40		if (si->lfb_depth == f->bits_per_pixel &&
     41		    si->red_size == f->red.length &&
     42		    si->red_pos == f->red.offset &&
     43		    si->green_size == f->green.length &&
     44		    si->green_pos == f->green.offset &&
     45		    si->blue_size == f->blue.length &&
     46		    si->blue_pos == f->blue.offset &&
     47		    si->rsvd_size == f->transp.length &&
     48		    si->rsvd_pos == f->transp.offset) {
     49			mode->format = f->name;
     50			mode->width = si->lfb_width;
     51			mode->height = si->lfb_height;
     52			mode->stride = si->lfb_linelength;
     53			return true;
     54		}
     55	}
     56
     57	return false;
     58}
     59
     60__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
     61						     const struct simplefb_platform_data *mode)
     62{
     63	struct platform_device *pd;
     64	struct resource res;
     65	u64 base, size;
     66	u32 length;
     67	int ret;
     68
     69	/*
     70	 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
     71	 * upper half of the base address. Assemble the address, then make sure
     72	 * it is valid and we can actually access it.
     73	 */
     74	base = si->lfb_base;
     75	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
     76		base |= (u64)si->ext_lfb_base << 32;
     77	if (!base || (u64)(resource_size_t)base != base) {
     78		printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
     79		return ERR_PTR(-EINVAL);
     80	}
     81
     82	/*
     83	 * Don't use lfb_size as IORESOURCE size, since it may contain the
     84	 * entire VMEM, and thus require huge mappings. Use just the part we
     85	 * need, that is, the part where the framebuffer is located. But verify
     86	 * that it does not exceed the advertised VMEM.
     87	 * Note that in case of VBE, the lfb_size is shifted by 16 bits for
     88	 * historical reasons.
     89	 */
     90	size = si->lfb_size;
     91	if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
     92		size <<= 16;
     93	length = mode->height * mode->stride;
     94	if (length > size) {
     95		printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
     96		return ERR_PTR(-EINVAL);
     97	}
     98	length = PAGE_ALIGN(length);
     99
    100	/* setup IORESOURCE_MEM as framebuffer memory */
    101	memset(&res, 0, sizeof(res));
    102	res.flags = IORESOURCE_MEM;
    103	res.name = simplefb_resname;
    104	res.start = base;
    105	res.end = res.start + length - 1;
    106	if (res.end <= res.start)
    107		return ERR_PTR(-EINVAL);
    108
    109	pd = platform_device_alloc("simple-framebuffer", 0);
    110	if (!pd)
    111		return ERR_PTR(-ENOMEM);
    112
    113	sysfb_apply_efi_quirks(pd);
    114
    115	ret = platform_device_add_resources(pd, &res, 1);
    116	if (ret)
    117		goto err_put_device;
    118
    119	ret = platform_device_add_data(pd, mode, sizeof(*mode));
    120	if (ret)
    121		goto err_put_device;
    122
    123	ret = platform_device_add(pd);
    124	if (ret)
    125		goto err_put_device;
    126
    127	return pd;
    128
    129err_put_device:
    130	platform_device_put(pd);
    131
    132	return ERR_PTR(ret);
    133}