[v11] firmware: google: Implement cbmem in sysfs driver

Message ID	20220929234432.3711480-1-jrosenth@chromium.org (mailing list archive)
State	Superseded
Headers	show Received: from mail-il1-f169.google.com (mail-il1-f169.google.com [209.85.166.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 472AD7B for <chrome-platform@lists.linux.dev>; Thu, 29 Sep 2022 23:44:41 +0000 (UTC) From: Jack Rosenthal <jrosenth@chromium.org> To: linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev, gregkh@linuxfoundation.org Cc: Jack Rosenthal <jrosenth@chromium.org>, Stephen Boyd <swboyd@chromium.org>, Tzung-Bi Shih <tzungbi@kernel.org>, Guenter Roeck <groeck@chromium.org>, Julius Werner <jwerner@chromium.org> Subject: [PATCH v11] firmware: google: Implement cbmem in sysfs driver Date: Thu, 29 Sep 2022 17:44:32 -0600 Message-Id: <20220929234432.3711480-1-jrosenth@chromium.org> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	[v11] firmware: google: Implement cbmem in sysfs driver \| expand [v11] firmware: google: Implement cbmem in sysfs driver

diff --git a/Documentation/ABI/testing/sysfs-firmware-cbmem b/Documentation/ABI/testing/sysfs-firmware-cbmem new file mode 100644 index 000000000000..f769104ac4cd --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-cbmem @@ -0,0 +1,43 @@ +What: /sys/firmware/cbmem/ +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + Coreboot provides a variety of data structures in CBMEM. This + directory contains each CBMEM entry, which can be found via + Coreboot tables. + +What: /sys/firmware/cbmem/<id>/ +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + Each CBMEM entry is given a directory based on 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``. + +What: /sys/firmware/cbmem/<id>/address +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + The pyhsical memory address that the CBMEM entry's data begins + at. + +What: /sys/firmware/cbmem/<id>/size +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + The size of the CBMEM entry's data. + +What: /sys/firmware/cbmem/<id>/id +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + The CBMEM id corresponding to the entry. + +What: /sys/firmware/cbmem/<id>/mem +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + A file exposing read/write access to the entry's data. Note + that this file does not support mmap(), as coreboot + does not guarantee that the data will be page-aligned. diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig index 983e07dc022e..485934cc9663 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. +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/cbmem. + 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/Makefile index d17caded5d88..8151e323cc43 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -7,5 +7,8 @@ obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT) += memconsole-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_X86_LEGACY) += memconsole-x86-legacy.o +# Must come after coreboot_table.o, as this driver depends on that bus type. +obj-$(CONFIG_GOOGLE_CBMEM) += cbmem.o + vpd-sysfs-y := vpd.o vpd_decode.o obj-$(CONFIG_GOOGLE_VPD) += vpd-sysfs.o diff --git a/drivers/firmware/google/cbmem.c b/drivers/firmware/google/cbmem.c new file mode 100644 index 000000000000..fe814589f641 --- /dev/null +++ b/drivers/firmware/google/cbmem.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * cbmem.c + * + * Driver for exporting cbmem entries in sysfs. + * + * Copyright 2022 Google LLC + */ + +#include <linux/device.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/kobject.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/sysfs.h> + +#include "coreboot_table.h" + +#define LB_TAG_CBMEM_ENTRY 0x31 + +static struct kobject *cbmem_kobj; +struct cbmem_entry { + char *mem_file_buf; + u32 size; + char *link_name; +}; + +static struct cbmem_entry *to_cbmem_entry(struct kobject *kobj) +{ + return dev_get_drvdata(kobj_to_dev(kobj)); +} + +static ssize_t mem_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, loff_t pos, + size_t count) +{ + struct cbmem_entry *entry = to_cbmem_entry(kobj); + + return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf, + entry->size); +} + +static ssize_t mem_write(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, loff_t pos, + size_t count) +{ + struct cbmem_entry *entry = to_cbmem_entry(kobj); + + if (pos < 0 || pos >= entry->size) + return -EINVAL; + if (count > entry->size - pos) + count = entry->size - pos; + + memcpy(entry->mem_file_buf + pos, buf, count); + return count; +} +static BIN_ATTR_ADMIN_RW(mem, 0); + +static ssize_t address_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct coreboot_device *cbdev = dev_to_coreboot_device(dev); + + return sysfs_emit(buf, "0x%llx\n", cbdev->cbmem_entry.address); +} +static DEVICE_ATTR_RO(address); + +static ssize_t size_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct coreboot_device *cbdev = dev_to_coreboot_device(dev); + + return sysfs_emit(buf, "0x%x\n", cbdev->cbmem_entry.entry_size); +} +static DEVICE_ATTR_RO(size); + +static ssize_t id_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct coreboot_device *cbdev = dev_to_coreboot_device(dev); + + return sysfs_emit(buf, "0x%08x\n", cbdev->cbmem_entry.id); +} +static DEVICE_ATTR_RO(id); + +static struct attribute *attrs[] = { + &dev_attr_address.attr, + &dev_attr_size.attr, + &dev_attr_id.attr, + NULL, +}; + +static struct bin_attribute *bin_attrs[] = { + &bin_attr_mem, + NULL, +}; + +static const struct attribute_group cbmem_entry_group = { + .attrs = attrs, + .bin_attrs = bin_attrs, +}; + +static const struct attribute_group *dev_groups[] = { + &cbmem_entry_group, + NULL, +}; + +static int cbmem_entry_probe(struct coreboot_device *dev) +{ + struct cbmem_entry *entry; + + entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + dev_set_drvdata(&dev->dev, entry); + entry->mem_file_buf = devm_memremap(&dev->dev, dev->cbmem_entry.address, + dev->cbmem_entry.entry_size, + MEMREMAP_WB); + if (!entry->mem_file_buf) + return -ENOMEM; + + entry->size = dev->cbmem_entry.entry_size; + + entry->link_name = devm_kasprintf(&dev->dev, GFP_KERNEL, "%08x", + dev->cbmem_entry.id); + if (!entry->link_name) + return -ENOMEM; + + return sysfs_create_link(cbmem_kobj, &dev->dev.kobj, entry->link_name); +} + +static void cbmem_entry_remove(struct coreboot_device *dev) +{ + struct cbmem_entry *entry = dev_get_drvdata(&dev->dev); + + sysfs_remove_link(cbmem_kobj, entry->link_name); +} + +static struct coreboot_driver cbmem_entry_driver = { + .probe = cbmem_entry_probe, + .remove = cbmem_entry_remove, + .drv = { + .name = "cbmem", + .owner = THIS_MODULE, + .dev_groups = dev_groups, + }, + .tag = LB_TAG_CBMEM_ENTRY, +}; + +static int __init cbmem_init(void) +{ + int ret; + + cbmem_kobj = kobject_create_and_add("cbmem", firmware_kobj); + if (!cbmem_kobj) + return -ENOMEM; + + ret = coreboot_driver_register(&cbmem_entry_driver); + if (ret) { + kobject_put(cbmem_kobj); + return ret; + } + + return 0; +} +module_init(cbmem_init); + +static void __exit cbmem_exit(void) +{ + kobject_put(cbmem_kobj); + coreboot_driver_unregister(&cbmem_entry_driver); +} +module_exit(cbmem_exit); + +MODULE_AUTHOR("Jack Rosenthal <jrosenth@chromium.org>"); +MODULE_LICENSE("GPL"); diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/google/coreboot_table.h index beb778674acd..4666fddf28d6 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; }; +/* 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; @@ -65,10 +75,16 @@ 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; }; }; +static inline struct coreboot_device *dev_to_coreboot_device(struct device *dev) +{ + return container_of(dev, struct coreboot_device, dev); +} + /* A driver for handling devices described in coreboot tables. */ struct coreboot_driver { int (*probe)(struct coreboot_device *);

[v11] firmware: google: Implement cbmem in sysfs driver

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