diff options
Diffstat (limited to 'drivers/firmware/sysfb_simplefb.c')
| -rw-r--r-- | drivers/firmware/sysfb_simplefb.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/firmware/sysfb_simplefb.c b/drivers/firmware/sysfb_simplefb.c new file mode 100644 index 0000000000..74363ed750 --- /dev/null +++ b/drivers/firmware/sysfb_simplefb.c @@ -0,0 +1,166 @@ +// 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 from the color bits, reserved bits and + * reported lfb_depth, whichever is highest. 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); + bits_per_pixel = max_t(u32, bits_per_pixel, si->lfb_depth); + } 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_set_efifb_fwnode(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); +} |