diff options
| -rw-r--r-- | drivers/firmware/Kconfig | 11 | ||||
| -rw-r--r-- | drivers/firmware/Makefile | 1 | ||||
| -rw-r--r-- | drivers/firmware/dmi-sysfs.c | 396 |
3 files changed, 408 insertions, 0 deletions
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig index e710424b59ea..3c56afc5eb1b 100644 --- a/drivers/firmware/Kconfig +++ b/drivers/firmware/Kconfig @@ -113,6 +113,17 @@ config DMIID information from userspace through /sys/class/dmi/id/ or if you want DMI-based module auto-loading. +config DMI_SYSFS + tristate "DMI table support in sysfs" + depends on SYSFS && DMI + default n + help + Say Y or M here to enable the exporting of the raw DMI table + data via sysfs. This is useful for consuming the data without + requiring any access to /dev/mem at all. Tables are found + under /sys/firmware/dmi when this option is enabled and + loaded. + config ISCSI_IBFT_FIND bool "iSCSI Boot Firmware Table Attributes" depends on X86 diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile index 1c3c17343dbe..20c17fca1232 100644 --- a/drivers/firmware/Makefile +++ b/drivers/firmware/Makefile @@ -2,6 +2,7 @@ # Makefile for the linux kernel. # obj-$(CONFIG_DMI) += dmi_scan.o +obj-$(CONFIG_DMI_SYSFS) += dmi-sysfs.o obj-$(CONFIG_EDD) += edd.o obj-$(CONFIG_EFI_VARS) += efivars.o obj-$(CONFIG_EFI_PCDP) += pcdp.o diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c new file mode 100644 index 000000000000..2d8a04a95085 --- /dev/null +++ b/drivers/firmware/dmi-sysfs.c @@ -0,0 +1,396 @@ +/* + * dmi-sysfs.c + * + * This module exports the DMI tables read-only to userspace through the + * sysfs file system. + * + * Data is currently found below + * /sys/firmware/dmi/... + * + * DMI attributes are presented in attribute files with names + * formatted using %d-%d, so that the first integer indicates the + * structure type (0-255), and the second field is the instance of that + * entry. + * + * Copyright 2011 Google, Inc. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kobject.h> +#include <linux/dmi.h> +#include <linux/capability.h> +#include <linux/slab.h> +#include <linux/list.h> +#include <linux/io.h> + +#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider + the top entry type is only 8 bits */ + +struct dmi_sysfs_entry { + struct dmi_header dh; + struct kobject kobj; + int instance; + int position; + struct list_head list; +}; + +/* + * Global list of dmi_sysfs_entry. Even though this should only be + * manipulated at setup and teardown, the lazy nature of the kobject + * system means we get lazy removes. + */ +static LIST_HEAD(entry_list); +static DEFINE_SPINLOCK(entry_list_lock); + +/* dmi_sysfs_attribute - Top level attribute. used by all entries. */ +struct dmi_sysfs_attribute { + struct attribute attr; + ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf); +}; + +#define DMI_SYSFS_ATTR(_entry, _name) \ +struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \ + .attr = {.name = __stringify(_name), .mode = 0400}, \ + .show = dmi_sysfs_##_entry##_##_name, \ +} + +/* + * dmi_sysfs_mapped_attribute - Attribute where we require the entry be + * mapped in. Use in conjunction with dmi_sysfs_specialize_attr_ops. + */ +struct dmi_sysfs_mapped_attribute { + struct attribute attr; + ssize_t (*show)(struct dmi_sysfs_entry *entry, + const struct dmi_header *dh, + char *buf); +}; + +#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \ +struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \ + .attr = {.name = __stringify(_name), .mode = 0400}, \ + .show = dmi_sysfs_##_entry##_##_name, \ +} + +/************************************************* + * Generic DMI entry support. + *************************************************/ + +static struct dmi_sysfs_entry *to_entry(struct kobject *kobj) +{ + return container_of(kobj, struct dmi_sysfs_entry, kobj); +} + +static struct dmi_sysfs_attribute *to_attr(struct attribute *attr) +{ + return container_of(attr, struct dmi_sysfs_attribute, attr); +} + +static ssize_t dmi_sysfs_attr_show(struct kobject *kobj, + struct attribute *_attr, char *buf) +{ + struct dmi_sysfs_entry *entry = to_entry(kobj); + struct dmi_sysfs_attribute *attr = to_attr(_attr); + + /* DMI stuff is only ever admin visible */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + return attr->show(entry, buf); +} + +static const struct sysfs_ops dmi_sysfs_attr_ops = { + .show = dmi_sysfs_attr_show, +}; + +typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *, + const struct dmi_header *dh, void *); + +struct find_dmi_data { + struct dmi_sysfs_entry *entry; + dmi_callback callback; + void *private; + int instance_countdown; + ssize_t ret; +}; + +static void find_dmi_entry_helper(const struct dmi_header *dh, + void *_data) +{ + struct find_dmi_data *data = _data; + struct dmi_sysfs_entry *entry = data->entry; + + /* Is this the entry we want? */ + if (dh->type != entry->dh.type) + return; + + if (data->instance_countdown != 0) { + /* try the next instance? */ + data->instance_countdown--; + return; + } + + /* + * Don't ever revisit the instance. Short circuit later + * instances by letting the instance_countdown run negative + */ + data->instance_countdown--; + + /* Found the entry */ + data->ret = data->callback(entry, dh, data->private); +} + +/* State for passing the read parameters through dmi_find_entry() */ +struct dmi_read_state { + char *buf; + loff_t pos; + size_t count; +}; + +static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry, + dmi_callback callback, void *private) +{ + struct find_dmi_data data = { + .entry = entry, + .callback = callback, + .private = private, + .instance_countdown = entry->instance, + .ret = -EIO, /* To signal the entry disappeared */ + }; + int ret; + + ret = dmi_walk(find_dmi_entry_helper, &data); + /* This shouldn't happen, but just in case. */ + if (ret) + return -EINVAL; + return data.ret; +} + +/* + * Calculate and return the byte length of the dmi entry identified by + * dh. This includes both the formatted portion as well as the + * unformatted string space, including the two trailing nul characters. + */ +static size_t dmi_entry_length(const struct dmi_header *dh) +{ + const char *p = (const char *)dh; + + p += dh->length; + + while (p[0] || p[1]) + p++; + + return 2 + p - (const char *)dh; +} + +/************************************************* + * Generic DMI entry support. + *************************************************/ + +static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf) +{ + return sprintf(buf, "%d\n", entry->dh.length); +} + +static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf) +{ + return sprintf(buf, "%d\n", entry->dh.handle); +} + +static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf) +{ + return sprintf(buf, "%d\n", entry->dh.type); +} + +static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry, + char *buf) +{ + return sprintf(buf, "%d\n", entry->instance); +} + +static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry, + char *buf) +{ + return sprintf(buf, "%d\n", entry->position); +} + +static DMI_SYSFS_ATTR(entry, length); +static DMI_SYSFS_ATTR(entry, handle); +static DMI_SYSFS_ATTR(entry, type); +static DMI_SYSFS_ATTR(entry, instance); +static DMI_SYSFS_ATTR(entry, position); + +static struct attribute *dmi_sysfs_entry_attrs[] = { + &dmi_sysfs_attr_entry_length.attr, + &dmi_sysfs_attr_entry_handle.attr, + &dmi_sysfs_attr_entry_type.attr, + &dmi_sysfs_attr_entry_instance.attr, + &dmi_sysfs_attr_entry_position.attr, + NULL, +}; + +static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry, + const struct dmi_header *dh, + void *_state) +{ + struct dmi_read_state *state = _state; + size_t entry_length; + + entry_length = dmi_entry_length(dh); + + return memory_read_from_buffer(state->buf, state->count, + &state->pos, dh, entry_length); +} + +static ssize_t dmi_entry_raw_read(struct file *filp, + struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t pos, size_t count) +{ + struct dmi_sysfs_entry *entry = to_entry(kobj); + struct dmi_read_state state = { + .buf = buf, + .pos = pos, + .count = count, + }; + + return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state); +} + +static const struct bin_attribute dmi_entry_raw_attr = { + .attr = {.name = "raw", .mode = 0400}, + .read = dmi_entry_raw_read, +}; + +static void dmi_sysfs_entry_release(struct kobject *kobj) +{ + struct dmi_sysfs_entry *entry = to_entry(kobj); + sysfs_remove_bin_file(&entry->kobj, &dmi_entry_raw_attr); + spin_lock(&entry_list_lock); + list_del(&entry->list); + spin_unlock(&entry_list_lock); + kfree(entry); +} + +static struct kobj_type dmi_sysfs_entry_ktype = { + .release = dmi_sysfs_entry_release, + .sysfs_ops = &dmi_sysfs_attr_ops, + .default_attrs = dmi_sysfs_entry_attrs, +}; + +static struct kobject *dmi_kobj; +static struct kset *dmi_kset; + +/* Global count of all instances seen. Only for setup */ +static int __initdata instance_counts[MAX_ENTRY_TYPE + 1]; + +/* Global positional count of all entries seen. Only for setup */ +static int __initdata position_count; + +static void __init dmi_sysfs_register_handle(const struct dmi_header *dh, + void *_ret) +{ + struct dmi_sysfs_entry *entry; + int *ret = _ret; + + /* If a previous entry saw an error, short circuit */ + if (*ret) + return; + + /* Allocate and register a new entry into the entries set */ + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) { + *ret = -ENOMEM; + return; + } + + /* Set the key */ + entry->dh = *dh; + entry->instance = instance_counts[dh->type]++; + entry->position = position_count++; + + entry->kobj.kset = dmi_kset; + *ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL, + "%d-%d", dh->type, entry->instance); + + if (*ret) { + kfree(entry); + return; + } + + /* Thread on the global list for cleanup */ + spin_lock(&entry_list_lock); + list_add_tail(&entry->list, &entry_list); + spin_unlock(&entry_list_lock); + + /* Create the raw binary file to access the entry */ + *ret = sysfs_create_bin_file(&entry->kobj, &dmi_entry_raw_attr); + if (*ret) + goto out_err; + + return; +out_err: + kobject_put(&entry->kobj); + return; +} + +static void cleanup_entry_list(void) +{ + struct dmi_sysfs_entry *entry, *next; + + /* No locks, we are on our way out */ + list_for_each_entry_safe(entry, next, &entry_list, list) { + kobject_put(&entry->kobj); + } +} + +static int __init dmi_sysfs_init(void) +{ + int error = -ENOMEM; + int val; + + /* Set up our directory */ + dmi_kobj = kobject_create_and_add("dmi", firmware_kobj); + if (!dmi_kobj) + goto err; + + dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj); + if (!dmi_kset) + goto err; + + val = 0; + error = dmi_walk(dmi_sysfs_register_handle, &val); + if (error) + goto err; + if (val) { + error = val; + goto err; + } + + pr_debug("dmi-sysfs: loaded.\n"); + + return 0; +err: + cleanup_entry_list(); + kset_unregister(dmi_kset); + kobject_put(dmi_kobj); + return error; +} + +/* clean up everything. */ +static void __exit dmi_sysfs_exit(void) +{ + pr_debug("dmi-sysfs: unloading.\n"); + cleanup_entry_list(); + kset_unregister(dmi_kset); + kobject_put(dmi_kobj); +} + +module_init(dmi_sysfs_init); +module_exit(dmi_sysfs_exit); + +MODULE_AUTHOR("Mike Waychison <mikew@google.com>"); +MODULE_DESCRIPTION("DMI sysfs support"); +MODULE_LICENSE("GPL"); |