sysfb_simplefb.c

  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	__u8 type;
 31	u32 bits_per_pixel;
 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	bits_per_pixel = __screen_info_lfb_bits_per_pixel(si);
 39
 40	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
 41		const struct simplefb_format *f = &formats[i];
 42
 43		if (f->transp.length)
 44			continue; /* transparent formats are unsupported by VESA/EFI */
 45
 46		if (bits_per_pixel == f->bits_per_pixel &&
 47		    si->red_size == f->red.length &&
 48		    si->red_pos == f->red.offset &&
 49		    si->green_size == f->green.length &&
 50		    si->green_pos == f->green.offset &&
 51		    si->blue_size == f->blue.length &&
 52		    si->blue_pos == f->blue.offset) {
 53			mode->format = f->name;
 54			mode->width = si->lfb_width;
 55			mode->height = si->lfb_height;
 56			mode->stride = si->lfb_linelength;
 57			return true;
 58		}
 59	}
 60
 61	return false;
 62}
 63
 64__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
 65						     const struct simplefb_platform_data *mode,
 66						     struct device *parent)
 67{
 68	struct platform_device *pd;
 69	struct resource res;
 70	u64 base, size;
 71	u32 length;
 72	int ret;
 73
 74	/*
 75	 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
 76	 * upper half of the base address. Assemble the address, then make sure
 77	 * it is valid and we can actually access it.
 78	 */
 79	base = si->lfb_base;
 80	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
 81		base |= (u64)si->ext_lfb_base << 32;
 82	if (!base || (u64)(resource_size_t)base != base) {
 83		printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
 84		return ERR_PTR(-EINVAL);
 85	}
 86
 87	/*
 88	 * Don't use lfb_size as IORESOURCE size, since it may contain the
 89	 * entire VMEM, and thus require huge mappings. Use just the part we
 90	 * need, that is, the part where the framebuffer is located. But verify
 91	 * that it does not exceed the advertised VMEM.
 92	 * Note that in case of VBE, the lfb_size is shifted by 16 bits for
 93	 * historical reasons.
 94	 */
 95	size = si->lfb_size;
 96	if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
 97		size <<= 16;
 98	length = mode->height * mode->stride;
 99	if (length > size) {
100		printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
101		return ERR_PTR(-EINVAL);
102	}
103	length = PAGE_ALIGN(length);
104
105	/* setup IORESOURCE_MEM as framebuffer memory */
106	memset(&res, 0, sizeof(res));
107	res.flags = IORESOURCE_MEM;
108	res.name = simplefb_resname;
109	res.start = base;
110	res.end = res.start + length - 1;
111	if (res.end <= res.start)
112		return ERR_PTR(-EINVAL);
113
114	pd = platform_device_alloc("simple-framebuffer", 0);
115	if (!pd)
116		return ERR_PTR(-ENOMEM);
117
118	pd->dev.parent = parent;
119
120	sysfb_set_efifb_fwnode(pd);
121
122	ret = platform_device_add_resources(pd, &res, 1);
123	if (ret)
124		goto err_put_device;
125
126	ret = platform_device_add_data(pd, mode, sizeof(*mode));
127	if (ret)
128		goto err_put_device;
129
130	ret = platform_device_add(pd);
131	if (ret)
132		goto err_put_device;
133
134	return pd;
135
136err_put_device:
137	platform_device_put(pd);
138
139	return ERR_PTR(ret);
140}