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On coreboot platforms, a system framebuffer may be provided to the Linux
kernel by filling a LB_TAG_FRAMEBUFFER entry in the coreboot table. But
a coreboot payload (e.g: SeaBIOS) could also provide its own framebuffer
information to the Linux kernel.
If that's the case, arch x86 boot code will fill the global screen_info
data and this used by the Generic System Framebuffers (sysfb) framework,
to register a platform device with pdata about the system's framebuffer.
But later, the framebuffer_coreboot driver will try to do the same and
attempt to register a "simple-framebuffer" platform device (using the
information from the coreboot table), which will lead to an error due a
device with the same name already being registered:
sysfs: cannot create duplicate filename '/bus/platform/devices/simple-framebuffer.0'
...
coreboot: could not register framebuffer
framebuffer coreboot8: probe with driver framebuffer failed with error -17
To prevent this issue, make the framebuffer_core driver to not register
a platform device if the global struct screen_info data has been filled.
Reported-by: Brian Norris <briannorris@chromium.org>
Closes: https://lore.kernel.org/all/ZuCG-DggNThuF4pj@b20ea791c01f/T/#ma7fb65acbc1a56042258adac910992bb225a20d2
Suggested-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Link: https://lore.kernel.org/r/20240916110040.1688511-3-javierm@redhat.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
115 lines
3.3 KiB
C
115 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* framebuffer-coreboot.c
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*
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* Memory based framebuffer accessed through coreboot table.
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*
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* Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com>
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* Copyright 2017 Google Inc.
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* Copyright 2017 Samuel Holland <samuel@sholland.org>
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*/
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#include <linux/device.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/platform_data/simplefb.h>
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#include <linux/platform_device.h>
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#include <linux/sysfb.h>
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#include "coreboot_table.h"
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#define CB_TAG_FRAMEBUFFER 0x12
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static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
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static int framebuffer_probe(struct coreboot_device *dev)
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{
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int i;
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u32 length;
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struct lb_framebuffer *fb = &dev->framebuffer;
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struct platform_device *pdev;
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struct resource res;
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struct simplefb_platform_data pdata = {
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.width = fb->x_resolution,
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.height = fb->y_resolution,
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.stride = fb->bytes_per_line,
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.format = NULL,
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};
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/*
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* On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry
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* in the coreboot table should only be used if the payload did
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* not pass a framebuffer information to the Linux kernel.
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*
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* If the global screen_info data has been filled, the Generic
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* System Framebuffers (sysfb) will already register a platform
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* device and pass that screen_info as platform_data to a driver
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* that can scan-out using the system provided framebuffer.
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*/
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if (sysfb_handles_screen_info())
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return -ENODEV;
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if (!fb->physical_address)
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return -ENODEV;
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for (i = 0; i < ARRAY_SIZE(formats); ++i) {
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if (fb->bits_per_pixel == formats[i].bits_per_pixel &&
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fb->red_mask_pos == formats[i].red.offset &&
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fb->red_mask_size == formats[i].red.length &&
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fb->green_mask_pos == formats[i].green.offset &&
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fb->green_mask_size == formats[i].green.length &&
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fb->blue_mask_pos == formats[i].blue.offset &&
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fb->blue_mask_size == formats[i].blue.length)
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pdata.format = formats[i].name;
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}
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if (!pdata.format)
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return -ENODEV;
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memset(&res, 0, sizeof(res));
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res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
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res.name = "Coreboot Framebuffer";
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res.start = fb->physical_address;
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length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
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res.end = res.start + length - 1;
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if (res.end <= res.start)
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return -EINVAL;
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pdev = platform_device_register_resndata(&dev->dev,
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"simple-framebuffer", 0,
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&res, 1, &pdata,
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sizeof(pdata));
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if (IS_ERR(pdev))
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pr_warn("coreboot: could not register framebuffer\n");
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else
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dev_set_drvdata(&dev->dev, pdev);
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return PTR_ERR_OR_ZERO(pdev);
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}
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static void framebuffer_remove(struct coreboot_device *dev)
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{
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struct platform_device *pdev = dev_get_drvdata(&dev->dev);
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platform_device_unregister(pdev);
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}
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static const struct coreboot_device_id framebuffer_ids[] = {
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{ .tag = CB_TAG_FRAMEBUFFER },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(coreboot, framebuffer_ids);
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static struct coreboot_driver framebuffer_driver = {
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.probe = framebuffer_probe,
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.remove = framebuffer_remove,
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.drv = {
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.name = "framebuffer",
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},
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.id_table = framebuffer_ids,
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};
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module_coreboot_driver(framebuffer_driver);
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MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
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MODULE_DESCRIPTION("Memory based framebuffer accessed through coreboot table");
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MODULE_LICENSE("GPL");
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