From nobody Sat Apr 11 21:28:51 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 920FBC19F2A for ; Thu, 4 Aug 2022 14:29:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239470AbiHDO3P (ORCPT ); Thu, 4 Aug 2022 10:29:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229988AbiHDO3M (ORCPT ); Thu, 4 Aug 2022 10:29:12 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDC691EC68 for ; Thu, 4 Aug 2022 07:29:10 -0700 (PDT) Received: by mail-pf1-x436.google.com with SMTP id u133so12844218pfc.10 for ; Thu, 04 Aug 2022 07:29:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=PB5Pdd8Gk1A9wUWsK/l+Gq3Mzcq4j94pVBZ2lMypZo0=; b=gK26PBj3bf+f3ywXFQiSNZ7xNroUdw/ZlHzd1Ezu7hGE1CKgg9bAnNfrtGHJTNnMzO fKwgyuwjEpdCyMYFPCzAg3XGHi5WE/lSiRBKkrp+xudq6cpCm4NSWOC3fVnDgkbC8eig Gn65Z43R8Pr1Q6y+IjQpJyMqMbJPVCeruwPfU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=PB5Pdd8Gk1A9wUWsK/l+Gq3Mzcq4j94pVBZ2lMypZo0=; b=Jrl+WD8uXScXKZo01DmDbOtl5Udt90n45bKl7QsHQF6zX4EaXup1NSKEpdcgdhonWs JIRhxc8jl3RHMlAT5RpKJox9nlk5tGbsGOEr/ufZzVCEHjYw2CwBzsmD+S7o8S5ujLyT 7NmQJHOOld8f/oCO1aD9wG6r2N/6A68UmAlWp5Hz5TnRP15S2f8eeOFOTSwCR3cr/DyB k7oFtRRZTrhjjQcGu/8nqro8HnrbulZSveUIFaKtpx0PoCA6dd4ObuXTMtAcaoBCZ5BI AXq4nAxJBt8zw/GekzeWvX5wh6nVl9n2Z1crxumhp0d/W8do98JDkwYqe3FTxHSrrZRS 3Jag== X-Gm-Message-State: ACgBeo12YLYp19pZMnz+gyep0VsNPa3DmIHZ1JsoUDUJ8U57TSXJ43YG d1vD62XbPppKjxypEl965+qKMmUdoME4MpDy X-Google-Smtp-Source: AA6agR7CPzTQe3LqSJ8JqpwRO9ESEXgXf59TlzzLoq9pANziAUlTZpGaRSyw+BS14Xj/KIldW0FgoQ== X-Received: by 2002:a05:6a00:4095:b0:52d:ee31:ec37 with SMTP id bw21-20020a056a00409500b0052dee31ec37mr2039793pfb.63.1659623350079; Thu, 04 Aug 2022 07:29:10 -0700 (PDT) Received: from jrosenth45.corp.google.com ([2620:0:1000:5e10:630b:1bd3:aad8:74fd]) by smtp.gmail.com with ESMTPSA id 196-20020a6215cd000000b0052d5e93fcb7sm1003323pfv.191.2022.08.04.07.29.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Aug 2022 07:29:09 -0700 (PDT) From: Jack Rosenthal To: linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev Cc: Jack Rosenthal , Stephen Boyd , Tzung-Bi Shih , Guenter Roeck , Julius Werner Subject: [PATCH v7] firmware: google: Implement cbmem in sysfs driver Date: Thu, 4 Aug 2022 07:28:56 -0700 Message-Id: <20220804142856.306032-1-jrosenth@chromium.org> X-Mailer: git-send-email 2.37.1.559.g78731f0fdb-goog In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" cbmem entries can be read from coreboot table 0x31 (LB_TAG_CBMEM_ENTRY). This commit exports access to cbmem entries in sysfs under /sys/firmware/coreboot/cbmem-*. Link: https://issuetracker.google.com/239604743 Cc: Stephen Boyd Cc: Tzung-Bi Shih Reviewed-by: Guenter Roeck Reviewed-by: Julius Werner Tested-by: Jack Rosenthal Signed-off-by: Jack Rosenthal --- v7: Updated commit message. .../ABI/testing/sysfs-firmware-coreboot | 17 ++ drivers/firmware/google/Kconfig | 8 + drivers/firmware/google/Makefile | 3 + drivers/firmware/google/cbmem.c | 232 ++++++++++++++++++ drivers/firmware/google/coreboot_table.h | 11 + 5 files changed, 271 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-firmware-coreboot create mode 100644 drivers/firmware/google/cbmem.c diff --git a/Documentation/ABI/testing/sysfs-firmware-coreboot b/Documentat= ion/ABI/testing/sysfs-firmware-coreboot new file mode 100644 index 000000000000..2401483bb86c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-coreboot @@ -0,0 +1,17 @@ +What: /sys/firmware/coreboot/ +Date: July 2022 +Contact: Jack Rosenthal +Description: + Coreboot-based BIOS firmware provides a variety of information + in CBMEM. Each CBMEM entry can be found via Coreboot tables. + For each CBMEM entry, the following are exposed: + + =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + address A hexidecimal value of the memory address the data for + the entry begins at. + size The size of the data stored. + id The id corresponding to the entry. A list of ids known + to coreboot can be found in the coreboot source tree at + ``src/commonlib/bsd/include/commonlib/bsd/cbmem_id.h`` + mem A file exposing the raw memory for the entry. + =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kcon= fig index 983e07dc022e..bf8316d1cb31 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -19,6 +19,14 @@ config GOOGLE_SMI driver provides an interface for reading and writing NVRAM variables. =20 +config GOOGLE_CBMEM + tristate "CBMEM entries in sysfs" + depends on GOOGLE_COREBOOT_TABLE + help + This option enables the kernel to search for Coreboot CBMEM + entries, and expose the memory for each entry in sysfs under + /sys/firmware/coreboot. + config GOOGLE_COREBOOT_TABLE tristate "Coreboot Table Access" depends on HAS_IOMEM && (ACPI || OF) diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Mak= efile index d17caded5d88..8151e323cc43 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -7,5 +7,8 @@ obj-$(CONFIG_GOOGLE_MEMCONSOLE) +=3D memconsole.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT) +=3D memconsole-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_X86_LEGACY) +=3D memconsole-x86-legacy.o =20 +# Must come after coreboot_table.o, as this driver depends on that bus typ= e. +obj-$(CONFIG_GOOGLE_CBMEM) +=3D cbmem.o + vpd-sysfs-y :=3D vpd.o vpd_decode.o obj-$(CONFIG_GOOGLE_VPD) +=3D vpd-sysfs.o diff --git a/drivers/firmware/google/cbmem.c b/drivers/firmware/google/cbme= m.c new file mode 100644 index 000000000000..9646a8047742 --- /dev/null +++ b/drivers/firmware/google/cbmem.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * cbmem.c + * + * Driver for exporting cbmem entries in sysfs. + * + * Copyright 2022 Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "coreboot_table.h" + +#define LB_TAG_CBMEM_ENTRY 0x31 + +static struct kobject *coreboot_kobj; + +struct cbmem_entry; +struct cbmem_entry_attr { + struct kobj_attribute kobj_attr; + struct cbmem_entry *entry; +}; + +struct cbmem_entry { + char *kobj_name; + struct kobject *kobj; + struct coreboot_device *dev; + struct bin_attribute mem_file; + char *mem_file_buf; + struct cbmem_entry_attr address_file; + struct cbmem_entry_attr size_file; + struct cbmem_entry_attr id_file; +}; + +static struct cbmem_entry_attr *to_cbmem_entry_attr(struct kobj_attribute = *a) +{ + return container_of(a, struct cbmem_entry_attr, kobj_attr); +} + +static ssize_t cbmem_entry_mem_read(struct file *filp, struct kobject *kob= p, + struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + struct cbmem_entry *entry =3D bin_attr->private; + + return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf, + bin_attr->size); +} + +static ssize_t cbmem_entry_mem_write(struct file *filp, struct kobject *ko= bp, + struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + struct cbmem_entry *entry =3D bin_attr->private; + + if (pos < 0 || pos >=3D bin_attr->size) + return -EINVAL; + if (count > bin_attr->size - pos) + count =3D bin_attr->size - pos; + + memcpy(entry->mem_file_buf + pos, buf, count); + return count; +} + +static ssize_t cbmem_entry_address_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr =3D to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%llx\n", + entry_attr->entry->dev->cbmem_entry.address); +} + +static ssize_t cbmem_entry_size_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr =3D to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%x\n", + entry_attr->entry->dev->cbmem_entry.entry_size); +} + +static ssize_t cbmem_entry_id_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr =3D to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%x\n", + entry_attr->entry->dev->cbmem_entry.id); +} + +static int cbmem_entry_setup(struct cbmem_entry *entry) +{ + int ret; + + entry->mem_file_buf =3D + devm_memremap(&entry->dev->dev, entry->dev->cbmem_entry.address, + entry->dev->cbmem_entry.entry_size, MEMREMAP_WB); + if (!entry->mem_file_buf) + return -ENOMEM; + + entry->kobj_name =3D devm_kasprintf(&entry->dev->dev, GFP_KERNEL, + "cbmem-%08x", + entry->dev->cbmem_entry.id); + if (!entry->kobj_name) + return -ENOMEM; + + entry->kobj =3D kobject_create_and_add(entry->kobj_name, coreboot_kobj); + if (!entry->kobj) + return -ENOMEM; + + sysfs_bin_attr_init(&entry->mem_file); + entry->mem_file.attr.name =3D "mem"; + entry->mem_file.attr.mode =3D 0664; + entry->mem_file.size =3D entry->dev->cbmem_entry.entry_size; + entry->mem_file.read =3D cbmem_entry_mem_read; + entry->mem_file.write =3D cbmem_entry_mem_write; + entry->mem_file.private =3D entry; + ret =3D sysfs_create_bin_file(entry->kobj, &entry->mem_file); + if (ret) + goto free_kobj; + + sysfs_attr_init(&entry->address_file.kobj_attr.attr); + entry->address_file.kobj_attr.attr.name =3D "address"; + entry->address_file.kobj_attr.attr.mode =3D 0444; + entry->address_file.kobj_attr.show =3D cbmem_entry_address_show; + entry->address_file.entry =3D entry; + ret =3D sysfs_create_file(entry->kobj, + &entry->address_file.kobj_attr.attr); + if (ret) + goto free_mem_file; + + sysfs_attr_init(&entry->size_file.kobj_attr.attr); + entry->size_file.kobj_attr.attr.name =3D "size"; + entry->size_file.kobj_attr.attr.mode =3D 0444; + entry->size_file.kobj_attr.show =3D cbmem_entry_size_show; + entry->size_file.entry =3D entry; + ret =3D sysfs_create_file(entry->kobj, &entry->size_file.kobj_attr.attr); + if (ret) + goto free_address_file; + + sysfs_attr_init(&entry->id_file.kobj_attr.attr); + entry->id_file.kobj_attr.attr.name =3D "id"; + entry->id_file.kobj_attr.attr.mode =3D 0444; + entry->id_file.kobj_attr.show =3D cbmem_entry_id_show; + entry->id_file.entry =3D entry; + ret =3D sysfs_create_file(entry->kobj, &entry->id_file.kobj_attr.attr); + if (ret) + goto free_size_file; + + return 0; + +free_size_file: + sysfs_remove_file(entry->kobj, &entry->size_file.kobj_attr.attr); +free_address_file: + sysfs_remove_file(entry->kobj, &entry->address_file.kobj_attr.attr); +free_mem_file: + sysfs_remove_bin_file(entry->kobj, &entry->mem_file); +free_kobj: + kobject_put(entry->kobj); + return ret; +} + +static int cbmem_entry_probe(struct coreboot_device *dev) +{ + struct cbmem_entry *entry; + + entry =3D devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + dev_set_drvdata(&dev->dev, entry); + entry->dev =3D dev; + return cbmem_entry_setup(entry); +} + +static void cbmem_entry_remove(struct coreboot_device *dev) +{ + struct cbmem_entry *entry =3D dev_get_drvdata(&dev->dev); + + sysfs_remove_bin_file(entry->kobj, &entry->mem_file); + sysfs_remove_file(entry->kobj, &entry->address_file.kobj_attr.attr); + sysfs_remove_file(entry->kobj, &entry->size_file.kobj_attr.attr); + sysfs_remove_file(entry->kobj, &entry->id_file.kobj_attr.attr); + kobject_put(entry->kobj); +} + +static struct coreboot_driver cbmem_entry_driver =3D { + .probe =3D cbmem_entry_probe, + .remove =3D cbmem_entry_remove, + .drv =3D { + .name =3D "cbmem", + }, + .tag =3D LB_TAG_CBMEM_ENTRY, +}; + +static int __init cbmem_init(void) +{ + int ret; + + coreboot_kobj =3D kobject_create_and_add("coreboot", firmware_kobj); + if (!coreboot_kobj) + return -ENOMEM; + + ret =3D coreboot_driver_register(&cbmem_entry_driver); + if (ret) { + kobject_put(coreboot_kobj); + return ret; + } + + return 0; +} +module_init(cbmem_init); + +static void __exit cbmem_exit(void) +{ + kobject_put(coreboot_kobj); + coreboot_driver_unregister(&cbmem_entry_driver); +} +module_exit(cbmem_exit); + +MODULE_AUTHOR("Jack Rosenthal "); +MODULE_LICENSE("GPL"); diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/go= ogle/coreboot_table.h index beb778674acd..6c03a8852d1b 100644 --- a/drivers/firmware/google/coreboot_table.h +++ b/drivers/firmware/google/coreboot_table.h @@ -39,6 +39,16 @@ struct lb_cbmem_ref { u64 cbmem_addr; }; =20 +/* Corresponds to LB_TAG_CBMEM_ENTRY. */ +struct lb_cbmem_entry { + u32 tag; + u32 size; + + u64 address; + u32 entry_size; + u32 id; +}; + /* Describes framebuffer setup by coreboot */ struct lb_framebuffer { u32 tag; @@ -65,6 +75,7 @@ struct coreboot_device { union { struct coreboot_table_entry entry; struct lb_cbmem_ref cbmem_ref; + struct lb_cbmem_entry cbmem_entry; struct lb_framebuffer framebuffer; }; }; --=20 2.37.1.559.g78731f0fdb-goog