ecea089164
On ARM64 systems coreboot defers framebuffer allocation to its payload, to be done by a libpayload function call. In this case, coreboot tables still include a framebuffer entry with display format details, but the physical address field is set to zero (as in [1], for example). Unfortunately, this field is not automatically updated when the framebuffer is initialized through libpayload, citing that doing so would invalidate checksums over the entire coreboot table [2]. This can be observed on ARM64 Chromebooks with stock firmware. On a Google Kevin (RK3399), trying to use coreboot framebuffer driver as built-in to the kernel results in a benign error. But on Google Hana (MT8173) and Google Cozmo (MT8183) it causes a hang. When the framebuffer physical address field in the coreboot table is zero, we have no idea where coreboot initialized a framebuffer, or even if it did. Instead of trying to set up a framebuffer located at zero, return ENODEV to indicate that there isn't one. [1] https://review.coreboot.org/c/coreboot/+/17109 [2] https://review.coreboot.org/c/coreboot/+/8797 Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> Reviewed-by: Julius Werner <jwerner@chromium.org> Link: https://lore.kernel.org/r/20231108182625.46563-1-alpernebiyasak@gmail.com Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
95 lines
2.5 KiB
C
95 lines
2.5 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 "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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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 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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.tag = CB_TAG_FRAMEBUFFER,
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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_LICENSE("GPL");
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