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Abdelkader Boudih
5f74217c05
Nexus-attached driver that discovers and parses coreboot's LBIO tables from physical memory. Exposes firmware metadata (version, build info, mainboard, serial config, TSC frequency, CBMEM entries) via sysctl hw.coreboot.*, the firmware console ring buffer via /dev/coreboot_console, and structured CBMEM entry access via /dev/cbmem ioctl interface. Tested on: - Qotom Q535G6 (Kabylake) - Intel NUC D54250WYK (Haswell) - Intel NUC D33217GKE (Ivy Bridge) - Dell 3100 2-in-1 (Gabbiter) - Dell 3100 (Fleex) - Lenovo IdeaPad 320s - Lenovo ThinkPad T480 - HP Chromebook 11 G4 - HP Chromebook 11 G5 - HP Chromebook 11 G6 EE - HP Chromebook 14 G4 - HP Chromebook 14 G5 - HP Chromebook x360 11 G1 EE - HP Chromebook x360 11 G2 EE - HP Chromebook x360 14 G1 - Acer C720 - Acer Chromebook 11 - Lenovo N22 Reviewed by: ngie, kib, adrian Differential Revision: https://reviews.freebsd.org/D55649
152 lines
2.9 KiB
C
152 lines
2.9 KiB
C
/*
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* Copyright (c) 2026 Abdelkader Boudih <[email protected]>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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/*
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* /dev/cbmem — ioctl interface for CBMEM entry enumeration and read
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*
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* Provides structured access to coreboot's CBMEM entries without
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* requiring /dev/mem. Entries can be listed (CBMEM_IOC_LIST) or
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* read by ID (CBMEM_IOC_READ).
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*/
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/conf.h>
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#include <sys/ioccom.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/uio.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <dev/coreboot/coreboot.h>
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static d_ioctl_t coreboot_cbmem_ioctl;
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static struct cdevsw coreboot_cbmem_cdevsw = {
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.d_version = D_VERSION,
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.d_ioctl = coreboot_cbmem_ioctl,
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.d_name = "cbmem",
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};
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/*
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* Find a CBMEM entry by its ID.
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*/
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static struct cbmem_entry_info *
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cbmem_find_entry(struct coreboot_softc *sc, uint32_t id)
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{
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uint32_t i;
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for (i = 0; i < sc->cbmem_count; i++) {
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if (sc->cbmem_entries[i].id == id)
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return (&sc->cbmem_entries[i]);
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}
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return (NULL);
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}
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static int
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coreboot_cbmem_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
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struct thread *td)
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{
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struct coreboot_softc *sc;
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int error;
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sc = dev->si_drv1;
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switch (cmd) {
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case CBMEM_IOC_LIST: {
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struct cbmem_list *list = (struct cbmem_list *)data;
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list->count = sc->cbmem_count;
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memcpy(list->entries, sc->cbmem_entries,
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sc->cbmem_count * sizeof(struct cbmem_entry_info));
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error = 0;
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break;
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}
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case CBMEM_IOC_READ: {
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struct cbmem_read_req *req = (struct cbmem_read_req *)data;
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struct cbmem_entry_info *info;
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void *mapped;
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vm_size_t map_size;
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uint64_t paddr;
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info = cbmem_find_entry(sc, req->id);
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if (info == NULL) {
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error = ENOENT;
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break;
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}
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if (req->offset >= info->size) {
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error = EINVAL;
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break;
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}
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if (req->size > info->size - req->offset)
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req->size = info->size - req->offset;
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if (req->size == 0) {
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error = 0;
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break;
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}
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if (info->address > UINT64_MAX - req->offset) {
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error = EINVAL;
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break;
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}
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paddr = info->address + req->offset;
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map_size = req->size;
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mapped = pmap_mapbios((vm_paddr_t)paddr, map_size);
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if (mapped == NULL) {
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error = ENOMEM;
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break;
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}
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error = copyout(mapped, req->buffer, req->size);
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pmap_unmapbios(mapped, map_size);
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break;
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}
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default:
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error = ENOTTY;
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break;
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}
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return (error);
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}
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int
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coreboot_cbmem_create(struct coreboot_softc *sc)
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{
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struct make_dev_args args;
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int error;
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if (sc->cbmem_count == 0)
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return (ENXIO);
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make_dev_args_init(&args);
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args.mda_devsw = &coreboot_cbmem_cdevsw;
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args.mda_uid = UID_ROOT;
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args.mda_gid = GID_WHEEL;
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args.mda_mode = 0440;
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args.mda_si_drv1 = sc;
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error = make_dev_s(&args, &sc->cbmem_cdev, "cbmem");
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if (error != 0)
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return (error);
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return (0);
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}
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void
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coreboot_cbmem_destroy(struct coreboot_softc *sc)
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{
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coreboot_cdev_destroy(&sc->cbmem_cdev);
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}
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