linux/drivers/firmware/dmi-sysfs.c
Ivan Khoronzhuk d7f96f97c4 firmware: dmi_scan: add SBMIOS entry and DMI tables
Some utils, like dmidecode and smbios, need to access SMBIOS entry
table area in order to get information like SMBIOS version, size, etc.
Currently it's done via /dev/mem. But for situation when /dev/mem
usage is disabled, the utils have to use dmi sysfs instead, which
doesn't represent SMBIOS entry and adds code/delay redundancy when direct
access for table is needed.

So this patch creates dmi/tables and adds SMBIOS entry point to allow
utils in question to work correctly without /dev/mem. Also patch adds
raw dmi table to simplify dmi table processing in user space, as
proposed by Jean Delvare.

Tested-by: Roy Franz <roy.franz@linaro.org>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
2015-06-25 09:06:56 +02:00

697 lines
17 KiB
C

/*
* 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;
struct kobject *child;
};
/*
* 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 void dmi_entry_free(struct kobject *kobj)
{
kfree(kobj);
}
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;
}
/*************************************************
* Support bits for specialized DMI entry support
*************************************************/
struct dmi_entry_attr_show_data {
struct attribute *attr;
char *buf;
};
static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
const struct dmi_header *dh,
void *_data)
{
struct dmi_entry_attr_show_data *data = _data;
struct dmi_sysfs_mapped_attribute *attr;
attr = container_of(data->attr,
struct dmi_sysfs_mapped_attribute, attr);
return attr->show(entry, dh, data->buf);
}
static ssize_t dmi_entry_attr_show(struct kobject *kobj,
struct attribute *attr,
char *buf)
{
struct dmi_entry_attr_show_data data = {
.attr = attr,
.buf = buf,
};
/* Find the entry according to our parent and call the
* normalized show method hanging off of the attribute */
return find_dmi_entry(to_entry(kobj->parent),
dmi_entry_attr_show_helper, &data);
}
static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
.show = dmi_entry_attr_show,
};
/*************************************************
* Specialized DMI entry support.
*************************************************/
/*** Type 15 - System Event Table ***/
#define DMI_SEL_ACCESS_METHOD_IO8 0x00
#define DMI_SEL_ACCESS_METHOD_IO2x8 0x01
#define DMI_SEL_ACCESS_METHOD_IO16 0x02
#define DMI_SEL_ACCESS_METHOD_PHYS32 0x03
#define DMI_SEL_ACCESS_METHOD_GPNV 0x04
struct dmi_system_event_log {
struct dmi_header header;
u16 area_length;
u16 header_start_offset;
u16 data_start_offset;
u8 access_method;
u8 status;
u32 change_token;
union {
struct {
u16 index_addr;
u16 data_addr;
} io;
u32 phys_addr32;
u16 gpnv_handle;
u32 access_method_address;
};
u8 header_format;
u8 type_descriptors_supported_count;
u8 per_log_type_descriptor_length;
u8 supported_log_type_descriptos[0];
} __packed;
#define DMI_SYSFS_SEL_FIELD(_field) \
static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
const struct dmi_header *dh, \
char *buf) \
{ \
struct dmi_system_event_log sel; \
if (sizeof(sel) > dmi_entry_length(dh)) \
return -EIO; \
memcpy(&sel, dh, sizeof(sel)); \
return sprintf(buf, "%u\n", sel._field); \
} \
static DMI_SYSFS_MAPPED_ATTR(sel, _field)
DMI_SYSFS_SEL_FIELD(area_length);
DMI_SYSFS_SEL_FIELD(header_start_offset);
DMI_SYSFS_SEL_FIELD(data_start_offset);
DMI_SYSFS_SEL_FIELD(access_method);
DMI_SYSFS_SEL_FIELD(status);
DMI_SYSFS_SEL_FIELD(change_token);
DMI_SYSFS_SEL_FIELD(access_method_address);
DMI_SYSFS_SEL_FIELD(header_format);
DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
static struct attribute *dmi_sysfs_sel_attrs[] = {
&dmi_sysfs_attr_sel_area_length.attr,
&dmi_sysfs_attr_sel_header_start_offset.attr,
&dmi_sysfs_attr_sel_data_start_offset.attr,
&dmi_sysfs_attr_sel_access_method.attr,
&dmi_sysfs_attr_sel_status.attr,
&dmi_sysfs_attr_sel_change_token.attr,
&dmi_sysfs_attr_sel_access_method_address.attr,
&dmi_sysfs_attr_sel_header_format.attr,
&dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
&dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
NULL,
};
static struct kobj_type dmi_system_event_log_ktype = {
.release = dmi_entry_free,
.sysfs_ops = &dmi_sysfs_specialize_attr_ops,
.default_attrs = dmi_sysfs_sel_attrs,
};
typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
loff_t offset);
static DEFINE_MUTEX(io_port_lock);
static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
loff_t offset)
{
u8 ret;
mutex_lock(&io_port_lock);
outb((u8)offset, sel->io.index_addr);
ret = inb(sel->io.data_addr);
mutex_unlock(&io_port_lock);
return ret;
}
static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
loff_t offset)
{
u8 ret;
mutex_lock(&io_port_lock);
outb((u8)offset, sel->io.index_addr);
outb((u8)(offset >> 8), sel->io.index_addr + 1);
ret = inb(sel->io.data_addr);
mutex_unlock(&io_port_lock);
return ret;
}
static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
loff_t offset)
{
u8 ret;
mutex_lock(&io_port_lock);
outw((u16)offset, sel->io.index_addr);
ret = inb(sel->io.data_addr);
mutex_unlock(&io_port_lock);
return ret;
}
static sel_io_reader sel_io_readers[] = {
[DMI_SEL_ACCESS_METHOD_IO8] = read_sel_8bit_indexed_io,
[DMI_SEL_ACCESS_METHOD_IO2x8] = read_sel_2x8bit_indexed_io,
[DMI_SEL_ACCESS_METHOD_IO16] = read_sel_16bit_indexed_io,
};
static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
const struct dmi_system_event_log *sel,
char *buf, loff_t pos, size_t count)
{
ssize_t wrote = 0;
sel_io_reader io_reader = sel_io_readers[sel->access_method];
while (count && pos < sel->area_length) {
count--;
*(buf++) = io_reader(sel, pos++);
wrote++;
}
return wrote;
}
static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
const struct dmi_system_event_log *sel,
char *buf, loff_t pos, size_t count)
{
u8 __iomem *mapped;
ssize_t wrote = 0;
mapped = ioremap(sel->access_method_address, sel->area_length);
if (!mapped)
return -EIO;
while (count && pos < sel->area_length) {
count--;
*(buf++) = readb(mapped + pos++);
wrote++;
}
iounmap(mapped);
return wrote;
}
static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
const struct dmi_header *dh,
void *_state)
{
struct dmi_read_state *state = _state;
struct dmi_system_event_log sel;
if (sizeof(sel) > dmi_entry_length(dh))
return -EIO;
memcpy(&sel, dh, sizeof(sel));
switch (sel.access_method) {
case DMI_SEL_ACCESS_METHOD_IO8:
case DMI_SEL_ACCESS_METHOD_IO2x8:
case DMI_SEL_ACCESS_METHOD_IO16:
return dmi_sel_raw_read_io(entry, &sel, state->buf,
state->pos, state->count);
case DMI_SEL_ACCESS_METHOD_PHYS32:
return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
state->pos, state->count);
case DMI_SEL_ACCESS_METHOD_GPNV:
pr_info("dmi-sysfs: GPNV support missing.\n");
return -EIO;
default:
pr_info("dmi-sysfs: Unknown access method %02x\n",
sel.access_method);
return -EIO;
}
}
static ssize_t dmi_sel_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->parent);
struct dmi_read_state state = {
.buf = buf,
.pos = pos,
.count = count,
};
return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
}
static struct bin_attribute dmi_sel_raw_attr = {
.attr = {.name = "raw_event_log", .mode = 0400},
.read = dmi_sel_raw_read,
};
static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
{
int ret;
entry->child = kzalloc(sizeof(*entry->child), GFP_KERNEL);
if (!entry->child)
return -ENOMEM;
ret = kobject_init_and_add(entry->child,
&dmi_system_event_log_ktype,
&entry->kobj,
"system_event_log");
if (ret)
goto out_free;
ret = sysfs_create_bin_file(entry->child, &dmi_sel_raw_attr);
if (ret)
goto out_del;
return 0;
out_del:
kobject_del(entry->child);
out_free:
kfree(entry->child);
return ret;
}
/*************************************************
* 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);
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 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 */
memcpy(&entry->dh, dh, sizeof(*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);
/* Handle specializations by type */
switch (dh->type) {
case DMI_ENTRY_SYSTEM_EVENT_LOG:
*ret = dmi_system_event_log(entry);
break;
default:
/* No specialization */
break;
}
if (*ret)
goto out_err;
/* 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->child);
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->child);
kobject_put(&entry->kobj);
}
}
static int __init dmi_sysfs_init(void)
{
int error;
int val;
if (!dmi_kobj) {
pr_err("dmi-sysfs: dmi entry is absent.\n");
error = -ENODATA;
goto err;
}
dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
if (!dmi_kset) {
error = -ENOMEM;
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);
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);
}
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");