8a0a62941a
Switch the plain 'tag' field in struct coreboot_driver for the newly created coreboot_device_id struct, which also contains a tag field and has the benefit of allowing modalias generation, and update all coreboot drivers accordingly. While at it, also add the id table for each driver to the module device table to allow automatically loading the module. Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com> Link: https://lore.kernel.org/r/20240212-coreboot-mod-defconfig-v4-3-d14172676f6d@collabora.com Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
117 lines
3.1 KiB
C
117 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* memconsole-coreboot.c
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*
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* Memory based BIOS console accessed through coreboot table.
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*
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* Copyright 2017 Google Inc.
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*/
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#include <linux/device.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include "memconsole.h"
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#include "coreboot_table.h"
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#define CB_TAG_CBMEM_CONSOLE 0x17
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/* CBMEM firmware console log descriptor. */
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struct cbmem_cons {
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u32 size_dont_access_after_boot;
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u32 cursor;
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u8 body[];
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} __packed;
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#define CURSOR_MASK ((1 << 28) - 1)
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#define OVERFLOW (1 << 31)
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static struct cbmem_cons *cbmem_console;
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static u32 cbmem_console_size;
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/*
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* The cbmem_console structure is read again on every access because it may
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* change at any time if runtime firmware logs new messages. This may rarely
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* lead to race conditions where the firmware overwrites the beginning of the
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* ring buffer with more lines after we have already read |cursor|. It should be
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* rare and harmless enough that we don't spend extra effort working around it.
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*/
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static ssize_t memconsole_coreboot_read(char *buf, loff_t pos, size_t count)
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{
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u32 cursor = cbmem_console->cursor & CURSOR_MASK;
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u32 flags = cbmem_console->cursor & ~CURSOR_MASK;
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u32 size = cbmem_console_size;
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struct seg { /* describes ring buffer segments in logical order */
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u32 phys; /* physical offset from start of mem buffer */
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u32 len; /* length of segment */
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} seg[2] = { {0}, {0} };
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size_t done = 0;
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int i;
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if (flags & OVERFLOW) {
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if (cursor > size) /* Shouldn't really happen, but... */
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cursor = 0;
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seg[0] = (struct seg){.phys = cursor, .len = size - cursor};
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seg[1] = (struct seg){.phys = 0, .len = cursor};
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} else {
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seg[0] = (struct seg){.phys = 0, .len = min(cursor, size)};
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}
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for (i = 0; i < ARRAY_SIZE(seg) && count > done; i++) {
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done += memory_read_from_buffer(buf + done, count - done, &pos,
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cbmem_console->body + seg[i].phys, seg[i].len);
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pos -= seg[i].len;
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}
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return done;
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}
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static int memconsole_probe(struct coreboot_device *dev)
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{
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struct cbmem_cons *tmp_cbmc;
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tmp_cbmc = memremap(dev->cbmem_ref.cbmem_addr,
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sizeof(*tmp_cbmc), MEMREMAP_WB);
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if (!tmp_cbmc)
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return -ENOMEM;
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/* Read size only once to prevent overrun attack through /dev/mem. */
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cbmem_console_size = tmp_cbmc->size_dont_access_after_boot;
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cbmem_console = devm_memremap(&dev->dev, dev->cbmem_ref.cbmem_addr,
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cbmem_console_size + sizeof(*cbmem_console),
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MEMREMAP_WB);
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memunmap(tmp_cbmc);
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if (IS_ERR(cbmem_console))
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return PTR_ERR(cbmem_console);
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memconsole_setup(memconsole_coreboot_read);
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return memconsole_sysfs_init();
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}
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static void memconsole_remove(struct coreboot_device *dev)
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{
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memconsole_exit();
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}
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static const struct coreboot_device_id memconsole_ids[] = {
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{ .tag = CB_TAG_CBMEM_CONSOLE },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(coreboot, memconsole_ids);
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static struct coreboot_driver memconsole_driver = {
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.probe = memconsole_probe,
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.remove = memconsole_remove,
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.drv = {
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.name = "memconsole",
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},
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.id_table = memconsole_ids,
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};
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module_coreboot_driver(memconsole_driver);
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MODULE_AUTHOR("Google, Inc.");
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MODULE_LICENSE("GPL");
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