kbuild: document howto build external modules using several directories

[linux-2.6/verdex.git] / drivers / firmware / efivars.c

/*
 * EFI Variables - efivars.c
 *
 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via sysfs
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Changelog:
 *
 *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   remove check for efi_enabled in exit
 *   add MODULE_VERSION
 *
 *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   minor bug fixes
 *
 *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
 *   converted driver to export variable information via sysfs
 *   and moved to drivers/firmware directory
 *   bumped revision number to v0.07 to reflect conversion & move
 *
 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   fix locking per Peter Chubb's findings
 *
 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
 *
 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   use list_for_each_safe when deleting vars.
 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
 *   v0.04 release to linux-ia64@linuxia64.org
 *
 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Moved vars from /proc/efi to /proc/efi/vars, and made
 *   efi.c own the /proc/efi directory.
 *   v0.03 release to linux-ia64@linuxia64.org
 *
 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   At the request of Stephane, moved ownership of /proc/efi
 *   to efi.c, and now efivars lives under /proc/efi/vars.
 *
 *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Feedback received from Stephane Eranian incorporated.
 *   efivar_write() checks copy_from_user() return value.
 *   efivar_read/write() returns proper errno.
 *   v0.02 release to linux-ia64@linuxia64.org
 *
 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   v0.01 release to linux-ia64@linuxia64.org
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/sched.h>                /* for capable() */
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/smp.h>
#include <linux/efi.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/device.h>

#include <asm/uaccess.h>

#define EFIVARS_VERSION "0.08"
#define EFIVARS_DATE "2004-May-17"

MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);

/*
 * efivars_lock protects two things:
 * 1) efivar_list - adds, removals, reads, writes
 * 2) efi.[gs]et_variable() calls.
 * It must not be held when creating sysfs entries or calling kmalloc.
 * efi.get_next_variable() is only called from efivars_init(),
 * which is protected by the BKL, so that path is safe.
 */
static DEFINE_SPINLOCK(efivars_lock);
static LIST_HEAD(efivar_list);

/*
 * The maximum size of VariableName + Data = 1024
 * Therefore, it's reasonable to save that much
 * space in each part of the structure,
 * and we use a page for reading/writing.
 */

struct efi_variable {
        efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
        efi_guid_t    VendorGuid;
        unsigned long DataSize;
        __u8          Data[1024];
        efi_status_t  Status;
        __u32         Attributes;
} __attribute__((packed));


struct efivar_entry {
        struct efi_variable var;
        struct list_head list;
        struct kobject kobj;
};

#define get_efivar_entry(n) list_entry(n, struct efivar_entry, list)

struct efivar_attribute {
        struct attribute attr;
        ssize_t (*show) (struct efivar_entry *entry, char *buf);
        ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
};


#define EFI_ATTR(_name, _mode, _show, _store) \
struct subsys_attribute efi_attr_##_name = { \
        .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
        .show = _show, \
        .store = _store, \
};

#define EFIVAR_ATTR(_name, _mode, _show, _store) \
struct efivar_attribute efivar_attr_##_name = { \
        .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
        .show = _show, \
        .store = _store, \
};

#define VAR_SUBSYS_ATTR(_name, _mode, _show, _store) \
struct subsys_attribute var_subsys_attr_##_name = { \
        .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
        .show = _show, \
        .store = _store, \
};

#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

/*
 * Prototype for sysfs creation function
 */
static int
efivar_create_sysfs_entry(unsigned long variable_name_size,
                                efi_char16_t *variable_name,
                                efi_guid_t *vendor_guid);

/* Return the number of unicode characters in data */
static unsigned long
utf8_strlen(efi_char16_t *data, unsigned long maxlength)
{
        unsigned long length = 0;

        while (*data++ != 0 && length < maxlength)
                length++;
        return length;
}

/*
 * Return the number of bytes is the length of this string
 * Note: this is NOT the same as the number of unicode characters
 */
static inline unsigned long
utf8_strsize(efi_char16_t *data, unsigned long maxlength)
{
        return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
}

static efi_status_t
get_var_data(struct efi_variable *var)
{
        efi_status_t status;

        spin_lock(&efivars_lock);
        var->DataSize = 1024;
        status = efi.get_variable(var->VariableName,
                                &var->VendorGuid,
                                &var->Attributes,
                                &var->DataSize,
                                var->Data);
        spin_unlock(&efivars_lock);
        if (status != EFI_SUCCESS) {
                printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
                        status);
        }
        return status;
}

static ssize_t
efivar_guid_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;

        if (!entry || !buf)
                return 0;

        efi_guid_unparse(&var->VendorGuid, str);
        str += strlen(str);
        str += sprintf(str, "\n");

        return str - buf;
}

static ssize_t
efivar_attr_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;
        efi_status_t status;

        if (!entry || !buf)
                return -EINVAL;

        status = get_var_data(var);
        if (status != EFI_SUCCESS)
                return -EIO;

        if (var->Attributes & 0x1)
                str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
        if (var->Attributes & 0x2)
                str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
        if (var->Attributes & 0x4)
                str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
        return str - buf;
}

static ssize_t
efivar_size_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;
        efi_status_t status;

        if (!entry || !buf)
                return -EINVAL;

        status = get_var_data(var);
        if (status != EFI_SUCCESS)
                return -EIO;

        str += sprintf(str, "0x%lx\n", var->DataSize);
        return str - buf;
}

static ssize_t
efivar_data_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        efi_status_t status;

        if (!entry || !buf)
                return -EINVAL;

        status = get_var_data(var);
        if (status != EFI_SUCCESS)
                return -EIO;

        memcpy(buf, var->Data, var->DataSize);
        return var->DataSize;
}
/*
 * We allow each variable to be edited via rewriting the
 * entire efi variable structure.
 */
static ssize_t
efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
{
        struct efi_variable *new_var, *var = &entry->var;
        efi_status_t status = EFI_NOT_FOUND;

        if (count != sizeof(struct efi_variable))
                return -EINVAL;

        new_var = (struct efi_variable *)buf;
        /*
         * If only updating the variable data, then the name
         * and guid should remain the same
         */
        if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
                efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
                printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
                return -EINVAL;
        }

        if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
                printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
                return -EINVAL;
        }

        spin_lock(&efivars_lock);
        status = efi.set_variable(new_var->VariableName,
                                        &new_var->VendorGuid,
                                        new_var->Attributes,
                                        new_var->DataSize,
                                        new_var->Data);

        spin_unlock(&efivars_lock);

        if (status != EFI_SUCCESS) {
                printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
                        status);
                return -EIO;
        }

        memcpy(&entry->var, new_var, count);
        return count;
}

static ssize_t
efivar_show_raw(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        efi_status_t status;

        if (!entry || !buf)
                return 0;

        status = get_var_data(var);
        if (status != EFI_SUCCESS)
                return -EIO;

        memcpy(buf, var, sizeof(*var));
        return sizeof(*var);
}

/*
 * Generic read/write functions that call the specific functions of
 * the atttributes...
 */
static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
                                char *buf)
{
        struct efivar_entry *var = to_efivar_entry(kobj);
        struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
        ssize_t ret = -EIO;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (efivar_attr->show) {
                ret = efivar_attr->show(var, buf);
        }
        return ret;
}

static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
                                const char *buf, size_t count)
{
        struct efivar_entry *var = to_efivar_entry(kobj);
        struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
        ssize_t ret = -EIO;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (efivar_attr->store)
                ret = efivar_attr->store(var, buf, count);

        return ret;
}

static struct sysfs_ops efivar_attr_ops = {
        .show = efivar_attr_show,
        .store = efivar_attr_store,
};

static void efivar_release(struct kobject *kobj)
{
        struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
        spin_lock(&efivars_lock);
        list_del(&var->list);
        spin_unlock(&efivars_lock);
        kfree(var);
}

static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

static struct attribute *def_attrs[] = {
        &efivar_attr_guid.attr,
        &efivar_attr_size.attr,
        &efivar_attr_attributes.attr,
        &efivar_attr_data.attr,
        &efivar_attr_raw_var.attr,
        NULL,
};

static struct kobj_type ktype_efivar = {
        .release = efivar_release,
        .sysfs_ops = &efivar_attr_ops,
        .default_attrs = def_attrs,
};

static ssize_t
dummy(struct subsystem *sub, char *buf)
{
        return -ENODEV;
}

static inline void
efivar_unregister(struct efivar_entry *var)
{
        kobject_unregister(&var->kobj);
}


static ssize_t
efivar_create(struct subsystem *sub, const char *buf, size_t count)
{
        struct efi_variable *new_var = (struct efi_variable *)buf;
        struct efivar_entry *search_efivar = NULL;
        unsigned long strsize1, strsize2;
        struct list_head *pos, *n;
        efi_status_t status = EFI_NOT_FOUND;
        int found = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        spin_lock(&efivars_lock);

        /*
         * Does this variable already exist?
         */
        list_for_each_safe(pos, n, &efivar_list) {
                search_efivar = get_efivar_entry(pos);
                strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
                strsize2 = utf8_strsize(new_var->VariableName, 1024);
                if (strsize1 == strsize2 &&
                        !memcmp(&(search_efivar->var.VariableName),
                                new_var->VariableName, strsize1) &&
                        !efi_guidcmp(search_efivar->var.VendorGuid,
                                new_var->VendorGuid)) {
                        found = 1;
                        break;
                }
        }
        if (found) {
                spin_unlock(&efivars_lock);
                return -EINVAL;
        }

        /* now *really* create the variable via EFI */
        status = efi.set_variable(new_var->VariableName,
                        &new_var->VendorGuid,
                        new_var->Attributes,
                        new_var->DataSize,
                        new_var->Data);

        if (status != EFI_SUCCESS) {
                printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
                        status);
                spin_unlock(&efivars_lock);
                return -EIO;
        }
        spin_unlock(&efivars_lock);

        /* Create the entry in sysfs.  Locking is not required here */
        status = efivar_create_sysfs_entry(utf8_strsize(new_var->VariableName,
                        1024), new_var->VariableName, &new_var->VendorGuid);
        if (status) {
                printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
        }
        return count;
}

static ssize_t
efivar_delete(struct subsystem *sub, const char *buf, size_t count)
{
        struct efi_variable *del_var = (struct efi_variable *)buf;
        struct efivar_entry *search_efivar = NULL;
        unsigned long strsize1, strsize2;
        struct list_head *pos, *n;
        efi_status_t status = EFI_NOT_FOUND;
        int found = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        spin_lock(&efivars_lock);

        /*
         * Does this variable already exist?
         */
        list_for_each_safe(pos, n, &efivar_list) {
                search_efivar = get_efivar_entry(pos);
                strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
                strsize2 = utf8_strsize(del_var->VariableName, 1024);
                if (strsize1 == strsize2 &&
                        !memcmp(&(search_efivar->var.VariableName),
                                del_var->VariableName, strsize1) &&
                        !efi_guidcmp(search_efivar->var.VendorGuid,
                                del_var->VendorGuid)) {
                        found = 1;
                        break;
                }
        }
        if (!found) {
                spin_unlock(&efivars_lock);
                return -EINVAL;
        }
        /* force the Attributes/DataSize to 0 to ensure deletion */
        del_var->Attributes = 0;
        del_var->DataSize = 0;

        status = efi.set_variable(del_var->VariableName,
                        &del_var->VendorGuid,
                        del_var->Attributes,
                        del_var->DataSize,
                        del_var->Data);

        if (status != EFI_SUCCESS) {
                printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
                        status);
                spin_unlock(&efivars_lock);
                return -EIO;
        }
        /* We need to release this lock before unregistering. */
        spin_unlock(&efivars_lock);

        efivar_unregister(search_efivar);

        /* It's dead Jim.... */
        return count;
}

static VAR_SUBSYS_ATTR(new_var, 0200, dummy, efivar_create);
static VAR_SUBSYS_ATTR(del_var, 0200, dummy, efivar_delete);

static struct subsys_attribute *var_subsys_attrs[] = {
        &var_subsys_attr_new_var,
        &var_subsys_attr_del_var,
        NULL,
};

/*
 * Let's not leave out systab information that snuck into
 * the efivars driver
 */
static ssize_t
systab_read(struct subsystem *entry, char *buf)
{
        char *str = buf;

        if (!entry || !buf)
                return -EINVAL;

        if (efi.mps)
                str += sprintf(str, "MPS=0x%lx\n", __pa(efi.mps));
        if (efi.acpi20)
                str += sprintf(str, "ACPI20=0x%lx\n", __pa(efi.acpi20));
        if (efi.acpi)
                str += sprintf(str, "ACPI=0x%lx\n", __pa(efi.acpi));
        if (efi.smbios)
                str += sprintf(str, "SMBIOS=0x%lx\n", __pa(efi.smbios));
        if (efi.hcdp)
                str += sprintf(str, "HCDP=0x%lx\n", __pa(efi.hcdp));
        if (efi.boot_info)
                str += sprintf(str, "BOOTINFO=0x%lx\n", __pa(efi.boot_info));
        if (efi.uga)
                str += sprintf(str, "UGA=0x%lx\n", __pa(efi.uga));

        return str - buf;
}

static EFI_ATTR(systab, 0400, systab_read, NULL);

static struct subsys_attribute *efi_subsys_attrs[] = {
        &efi_attr_systab,
        NULL,   /* maybe more in the future? */
};

static decl_subsys(vars, &ktype_efivar, NULL);
static decl_subsys(efi, NULL, NULL);

/*
 * efivar_create_sysfs_entry()
 * Requires:
 *    variable_name_size = number of bytes required to hold
 *                         variable_name (not counting the NULL
 *                         character at the end.
 *    efivars_lock is not held on entry or exit.
 * Returns 1 on failure, 0 on success
 */
static int
efivar_create_sysfs_entry(unsigned long variable_name_size,
                        efi_char16_t *variable_name,
                        efi_guid_t *vendor_guid)
{
        int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
        char *short_name;
        struct efivar_entry *new_efivar;

        short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
        new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);

        if (!short_name || !new_efivar)  {
                kfree(short_name);
                kfree(new_efivar);
                return 1;
        }

        memcpy(new_efivar->var.VariableName, variable_name,
                variable_name_size);
        memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));

        /* Convert Unicode to normal chars (assume top bits are 0),
           ala UTF-8 */
        for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
                short_name[i] = variable_name[i] & 0xFF;
        }
        /* This is ugly, but necessary to separate one vendor's
           private variables from another's.         */

        *(short_name + strlen(short_name)) = '-';
        efi_guid_unparse(vendor_guid, short_name + strlen(short_name));

        kobject_set_name(&new_efivar->kobj, "%s", short_name);
        kobj_set_kset_s(new_efivar, vars_subsys);
        kobject_register(&new_efivar->kobj);

        kfree(short_name);
        short_name = NULL;

        spin_lock(&efivars_lock);
        list_add(&new_efivar->list, &efivar_list);
        spin_unlock(&efivars_lock);

        return 0;
}
/*
 * For now we register the efi subsystem with the firmware subsystem
 * and the vars subsystem with the efi subsystem.  In the future, it
 * might make sense to split off the efi subsystem into its own
 * driver, but for now only efivars will register with it, so just
 * include it here.
 */

static int __init
efivars_init(void)
{
        efi_status_t status = EFI_NOT_FOUND;
        efi_guid_t vendor_guid;
        efi_char16_t *variable_name;
        struct subsys_attribute *attr;
        unsigned long variable_name_size = 1024;
        int i, error = 0;

        if (!efi_enabled)
                return -ENODEV;

        variable_name = kzalloc(variable_name_size, GFP_KERNEL);
        if (!variable_name) {
                printk(KERN_ERR "efivars: Memory allocation failed.\n");
                return -ENOMEM;
        }

        printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
               EFIVARS_DATE);

        /*
         * For now we'll register the efi subsys within this driver
         */

        error = firmware_register(&efi_subsys);

        if (error) {
                printk(KERN_ERR "efivars: Firmware registration failed with error %d.\n", error);
                goto out_free;
        }

        kset_set_kset_s(&vars_subsys, efi_subsys);

        error = subsystem_register(&vars_subsys);

        if (error) {
                printk(KERN_ERR "efivars: Subsystem registration failed with error %d.\n", error);
                goto out_firmware_unregister;
        }

        /*
         * Per EFI spec, the maximum storage allocated for both
         * the variable name and variable data is 1024 bytes.
         */

        do {
                variable_name_size = 1024;

                status = efi.get_next_variable(&variable_name_size,
                                                variable_name,
                                                &vendor_guid);
                switch (status) {
                case EFI_SUCCESS:
                        efivar_create_sysfs_entry(variable_name_size,
                                                        variable_name,
                                                        &vendor_guid);
                        break;
                case EFI_NOT_FOUND:
                        break;
                default:
                        printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
                                status);
                        status = EFI_NOT_FOUND;
                        break;
                }
        } while (status != EFI_NOT_FOUND);

        /*
         * Now add attributes to allow creation of new vars
         * and deletion of existing ones...
         */

        for (i = 0; (attr = var_subsys_attrs[i]) && !error; i++) {
                if (attr->show && attr->store)
                        error = subsys_create_file(&vars_subsys, attr);
        }

        /* Don't forget the systab entry */

        for (i = 0; (attr = efi_subsys_attrs[i]) && !error; i++) {
                if (attr->show)
                        error = subsys_create_file(&efi_subsys, attr);
        }

        if (error)
                printk(KERN_ERR "efivars: Sysfs attribute export failed with error %d.\n", error);
        else
                goto out_free;

        subsystem_unregister(&vars_subsys);

out_firmware_unregister:
        firmware_unregister(&efi_subsys);

out_free:
        kfree(variable_name);

        return error;
}

static void __exit
efivars_exit(void)
{
        struct list_head *pos, *n;

        list_for_each_safe(pos, n, &efivar_list)
                efivar_unregister(get_efivar_entry(pos));

        subsystem_unregister(&vars_subsys);
        firmware_unregister(&efi_subsys);
}

module_init(efivars_init);
module_exit(efivars_exit);