drivers/firmware/sysfb_simplefb.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Generic System Framebuffers
0004  * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
0005  */
0006
0007 /*
0008  * simple-framebuffer probing
0009  * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
0010  * If the mode is incompatible, we return "false" and let the caller create
0011  * legacy nodes instead.
0012  */
0013
0014 #include <linux/err.h>
0015 #include <linux/init.h>
0016 #include <linux/kernel.h>
0017 #include <linux/mm.h>
0018 #include <linux/platform_data/simplefb.h>
0019 #include <linux/platform_device.h>
0020 #include <linux/screen_info.h>
0021 #include <linux/sysfb.h>
0022
0023 static const char simplefb_resname[] = "BOOTFB";
0024 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
0025
0026 /* try parsing screen_info into a simple-framebuffer mode struct */
0027 __init bool sysfb_parse_mode(const struct screen_info *si,
0028                  struct simplefb_platform_data *mode)
0029 {
0030     const struct simplefb_format *f;
0031     __u8 type;
0032     unsigned int i;
0033
0034     type = si->orig_video_isVGA;
0035     if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
0036         return false;
0037
0038     for (i = 0; i < ARRAY_SIZE(formats); ++i) {
0039         f = &formats[i];
0040         if (si->lfb_depth == f->bits_per_pixel &&
0041             si->red_size == f->red.length &&
0042             si->red_pos == f->red.offset &&
0043             si->green_size == f->green.length &&
0044             si->green_pos == f->green.offset &&
0045             si->blue_size == f->blue.length &&
0046             si->blue_pos == f->blue.offset &&
0047             si->rsvd_size == f->transp.length &&
0048             si->rsvd_pos == f->transp.offset) {
0049             mode->format = f->name;
0050             mode->width = si->lfb_width;
0051             mode->height = si->lfb_height;
0052             mode->stride = si->lfb_linelength;
0053             return true;
0054         }
0055     }
0056
0057     return false;
0058 }
0059
0060 __init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
0061                              const struct simplefb_platform_data *mode)
0062 {
0063     struct platform_device *pd;
0064     struct resource res;
0065     u64 base, size;
0066     u32 length;
0067     int ret;
0068
0069     /*
0070      * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
0071      * upper half of the base address. Assemble the address, then make sure
0072      * it is valid and we can actually access it.
0073      */
0074     base = si->lfb_base;
0075     if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
0076         base |= (u64)si->ext_lfb_base << 32;
0077     if (!base || (u64)(resource_size_t)base != base) {
0078         printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
0079         return ERR_PTR(-EINVAL);
0080     }
0081
0082     /*
0083      * Don't use lfb_size as IORESOURCE size, since it may contain the
0084      * entire VMEM, and thus require huge mappings. Use just the part we
0085      * need, that is, the part where the framebuffer is located. But verify
0086      * that it does not exceed the advertised VMEM.
0087      * Note that in case of VBE, the lfb_size is shifted by 16 bits for
0088      * historical reasons.
0089      */
0090     size = si->lfb_size;
0091     if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
0092         size <<= 16;
0093     length = mode->height * mode->stride;
0094     if (length > size) {
0095         printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
0096         return ERR_PTR(-EINVAL);
0097     }
0098     length = PAGE_ALIGN(length);
0099
0100     /* setup IORESOURCE_MEM as framebuffer memory */
0101     memset(&res, 0, sizeof(res));
0102     res.flags = IORESOURCE_MEM;
0103     res.name = simplefb_resname;
0104     res.start = base;
0105     res.end = res.start + length - 1;
0106     if (res.end <= res.start)
0107         return ERR_PTR(-EINVAL);
0108
0109     pd = platform_device_alloc("simple-framebuffer", 0);
0110     if (!pd)
0111         return ERR_PTR(-ENOMEM);
0112
0113     sysfb_apply_efi_quirks(pd);
0114
0115     ret = platform_device_add_resources(pd, &res, 1);
0116     if (ret)
0117         goto err_put_device;
0118
0119     ret = platform_device_add_data(pd, mode, sizeof(*mode));
0120     if (ret)
0121         goto err_put_device;
0122
0123     ret = platform_device_add(pd);
0124     if (ret)
0125         goto err_put_device;
0126
0127     return pd;
0128
0129 err_put_device:
0130     platform_device_put(pd);
0131
0132     return ERR_PTR(ret);
0133 }