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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic System Framebuffers
* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
*/
/*
* simple-framebuffer probing
* Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
* If the mode is incompatible, we return "false" and let the caller create
* legacy nodes instead.
*/
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/screen_info.h>
#include <linux/sysfb.h>
static const char simplefb_resname[] = "BOOTFB";
static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
/* try parsing screen_info into a simple-framebuffer mode struct */
__init bool sysfb_parse_mode(const struct screen_info *si,
struct simplefb_platform_data *mode)
{
__u8 type;
u32 bits_per_pixel;
unsigned int i;
type = si->orig_video_isVGA;
if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
return false;
/*
* The meaning of depth and bpp for direct-color formats is
* inconsistent:
*
* - DRM format info specifies depth as the number of color
* bits; including alpha, but not including filler bits.
* - Linux' EFI platform code computes lfb_depth from the
* individual color channels, including the reserved bits.
* - VBE 1.1 defines lfb_depth for XRGB1555 as 16, but later
* versions use 15.
* - On the kernel command line, 'bpp' of 32 is usually
* XRGB8888 including the filler bits, but 15 is XRGB1555
* not including the filler bit.
*
* It's not easily possible to fix this in struct screen_info,
* as this could break UAPI. The best solution is to compute
* bits_per_pixel here and ignore lfb_depth. In the loop below,
* ignore simplefb formats with alpha bits, as EFI and VESA
* don't specify alpha channels.
*/
if (si->lfb_depth > 8) {
bits_per_pixel = max(max3(si->red_size + si->red_pos,
si->green_size + si->green_pos,
si->blue_size + si->blue_pos),
si->rsvd_size + si->rsvd_pos);
} else {
bits_per_pixel = si->lfb_depth;
}
for (i = 0; i < ARRAY_SIZE(formats); ++i) {
const struct simplefb_format *f = &formats[i];
if (f->transp.length)
continue; /* transparent formats are unsupported by VESA/EFI */
if (bits_per_pixel == f->bits_per_pixel &&
si->red_size == f->red.length &&
si->red_pos == f->red.offset &&
si->green_size == f->green.length &&
si->green_pos == f->green.offset &&
si->blue_size == f->blue.length &&
si->blue_pos == f->blue.offset) {
mode->format = f->name;
mode->width = si->lfb_width;
mode->height = si->lfb_height;
mode->stride = si->lfb_linelength;
return true;
}
}
return false;
}
__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
const struct simplefb_platform_data *mode)
{
struct platform_device *pd;
struct resource res;
u64 base, size;
u32 length;
int ret;
/*
* If the 64BIT_BASE capability is set, ext_lfb_base will contain the
* upper half of the base address. Assemble the address, then make sure
* it is valid and we can actually access it.
*/
base = si->lfb_base;
if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
base |= (u64)si->ext_lfb_base << 32;
if (!base || (u64)(resource_size_t)base != base) {
printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
return ERR_PTR(-EINVAL);
}
/*
* Don't use lfb_size as IORESOURCE size, since it may contain the
* entire VMEM, and thus require huge mappings. Use just the part we
* need, that is, the part where the framebuffer is located. But verify
* that it does not exceed the advertised VMEM.
* Note that in case of VBE, the lfb_size is shifted by 16 bits for
* historical reasons.
*/
size = si->lfb_size;
if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
size <<= 16;
length = mode->height * mode->stride;
if (length > size) {
printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
return ERR_PTR(-EINVAL);
}
length = PAGE_ALIGN(length);
/* setup IORESOURCE_MEM as framebuffer memory */
memset(&res, 0, sizeof(res));
res.flags = IORESOURCE_MEM;
res.name = simplefb_resname;
res.start = base;
res.end = res.start + length - 1;
if (res.end <= res.start)
return ERR_PTR(-EINVAL);
pd = platform_device_alloc("simple-framebuffer", 0);
if (!pd)
return ERR_PTR(-ENOMEM);
sysfb_apply_efi_quirks(pd);
ret = platform_device_add_resources(pd, &res, 1);
if (ret)
goto err_put_device;
ret = platform_device_add_data(pd, mode, sizeof(*mode));
if (ret)
goto err_put_device;
ret = platform_device_add(pd);
if (ret)
goto err_put_device;
return pd;
err_put_device:
platform_device_put(pd);
return ERR_PTR(ret);
}
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