/*
 * EFI Variables - efivars.c
 *
 * Copyright (C) 2001 Dell Computer Corporation <Matt_Domsch@dell.com>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via /proc
 *
 * Reads to /proc/efi/vars/varname return an efi_variable_t structure.
 * Writes to /proc/efi/vars/varname must be an efi_variable_t structure.
 * Writes with DataSize = 0 or Attributes = 0 deletes the variable.
 * Writes with a new value in VariableName+VendorGuid creates
 * a new variable.
 *
 *
 *  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:
 *
 *  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/proc_fs.h>
#include <linux/sched.h>                /* for capable() */
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/efi.h>

#include <asm/uaccess.h>

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

#define EFIVARS_VERSION "0.06 2002-Dec-10"

static int
efivar_read(char *page, char **start, off_t off,
            int count, int *eof, void *data);
static int
efivar_write(struct file *file, const char *buffer,
             unsigned long count, void *data);


/*
 * 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.
 */

typedef struct _efi_variable_t {
        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)) efi_variable_t;


typedef struct _efivar_entry_t {
        efi_variable_t          var;
        struct proc_dir_entry   *entry;
        struct list_head        list;
} efivar_entry_t;

/*
  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 proc 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 spinlock_t efivars_lock = SPIN_LOCK_UNLOCKED;
static LIST_HEAD(efivar_list);
static struct proc_dir_entry *efi_vars_dir;

#define efivar_entry(n) list_entry(n, efivar_entry_t, list)

/* 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 int
proc_calc_metrics(char *page, char **start, off_t off,
                  int count, int *eof, int len)
{
        if (len <= off+count) *eof = 1;
        *start = page + off;
        len -= off;
        if (len>count) len = count;
        if (len<0) len = 0;
        return len;
}

/*
 * efivar_create_proc_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_proc_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;
        efivar_entry_t *new_efivar;

        short_name = kmalloc(short_name_size+1, GFP_KERNEL);
        new_efivar = kmalloc(sizeof(efivar_entry_t), GFP_KERNEL);

        if (!short_name || !new_efivar)  {
                if (short_name)        kfree(short_name);
                if (new_efivar)        kfree(new_efivar);
                return 1;
        }
        memset(short_name, 0, short_name_size+1);
        memset(new_efivar, 0, sizeof(efivar_entry_t));

        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));

        /* Create the entry in proc */
        new_efivar->entry = create_proc_entry(short_name, 0600, efi_vars_dir);
        kfree(short_name); short_name = NULL;
        if (!new_efivar->entry) return 1;

        new_efivar->entry->data = new_efivar;
        new_efivar->entry->read_proc = efivar_read;
        new_efivar->entry->write_proc = efivar_write;

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

        return 0;
}



/***********************************************************
 * efivar_read()
 * Requires:
 * Modifies: page
 * Returns: number of bytes written, or -EINVAL on failure
 ***********************************************************/

static int
efivar_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
        int len = sizeof(efi_variable_t);
        efivar_entry_t *efi_var = data;
        efi_variable_t *var_data = (efi_variable_t *)page;

        if (!page || !data) return -EINVAL;

        spin_lock(&efivars_lock);
        MOD_INC_USE_COUNT;

        memcpy(var_data, &efi_var->var, len);

        var_data->DataSize = 1024;
        var_data->Status = efi.get_variable(var_data->VariableName,
                                            &var_data->VendorGuid,
                                            &var_data->Attributes,
                                            &var_data->DataSize,
                                            var_data->Data);

        MOD_DEC_USE_COUNT;
        spin_unlock(&efivars_lock);

        return proc_calc_metrics(page, start, off, count, eof, len);
}

/***********************************************************
 * efivar_write()
 * Requires: data is an efi_setvariable_t data type,
 *           properly filled in, possibly by a call
 *           first to efivar_read().
 *           Caller must have CAP_SYS_ADMIN
 * Modifies: NVRAM
 * Returns: var_data->DataSize on success, errno on failure
 *
 ***********************************************************/
static int
efivar_write(struct file *file, const char *buffer,
             unsigned long count, void *data)
{
        unsigned long strsize1, strsize2;
        int found=0;
        struct list_head *pos, *n;
        unsigned long size = sizeof(efi_variable_t);
        efi_status_t status;
        efivar_entry_t *efivar = data, *search_efivar = NULL;
        efi_variable_t *var_data;
        if (!data || count != size) {
                printk(KERN_WARNING "efivars: improper struct of size 0x%lx passed.\n", count);
                return -EINVAL;
        }
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        MOD_INC_USE_COUNT;

        var_data = kmalloc(size, GFP_KERNEL);
        if (!var_data) {
                MOD_DEC_USE_COUNT;
                return -ENOMEM;
        }
        if (copy_from_user(var_data, buffer, size)) {
                MOD_DEC_USE_COUNT;
                kfree(var_data);
                return -EFAULT;
        }

        spin_lock(&efivars_lock);

        /* Since the data ptr we've currently got is probably for
           a different variable find the right variable.
           This allows any properly formatted data structure to
           be written to any of the files in /proc/efi/vars and it will work.
        */
        list_for_each_safe(pos, n, &efivar_list) {
                search_efivar = efivar_entry(pos);
                strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
                strsize2 = utf8_strsize(var_data->VariableName, 1024);
                if ( strsize1 == strsize2 &&
                     !memcmp(&(search_efivar->var.VariableName),
                             var_data->VariableName, strsize1) &&
                     !efi_guidcmp(search_efivar->var.VendorGuid,
                                  var_data->VendorGuid)) {
                        found = 1;
                        break;
                }
        }
        if (found) efivar = search_efivar;

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

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


        if (!var_data->DataSize || !var_data->Attributes) {
                /* We just deleted the NVRAM variable */
                remove_proc_entry(efivar->entry->name, efi_vars_dir);
                list_del(&efivar->list);
                kfree(efivar);
        }

        spin_unlock(&efivars_lock);

        /* If this is a new variable, set up the proc entry for it. */
        if (!found) {
                efivar_create_proc_entry(utf8_strsize(var_data->VariableName,
                                                      1024),
                                         var_data->VariableName,
                                         &var_data->VendorGuid);
        }

        kfree(var_data);
        MOD_DEC_USE_COUNT;
        return size;
}

/*
 * The EFI system table contains pointers to the SAL system table,
 * HCDP, ACPI, SMBIOS, etc, that may be useful to applications.
 */
static ssize_t
efi_systab_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
{
        void *data;
        u8 *proc_buffer;
        ssize_t size, length;
        int ret;
        const int max_nr_entries = 7;   /* num ptrs to tables we could expose */
        const int max_line_len = 80;
        loff_t pos = *ppos;

        if (!efi.systab)
                return 0;

        proc_buffer = kmalloc(max_nr_entries * max_line_len, GFP_KERNEL);
        if (!proc_buffer)
                return -ENOMEM;

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

        if (pos != (unsigned) pos || pos >= length) {
                ret = 0;
                goto out;
        }

        data = proc_buffer + pos;
        size = length - pos;
        if (size > count)
                size = count;
        if (copy_to_user(buffer, data, size)) {
                ret = -EFAULT;
                goto out;
        }

        *ppos = pos + size;
        ret = size;

out:
        kfree(proc_buffer);
        return ret;
}

static struct proc_dir_entry *efi_systab_entry;
static struct file_operations efi_systab_fops = {
        .read = efi_systab_read,
};

static int __init
efivars_init(void)
{
        efi_status_t status;
        efi_guid_t vendor_guid;
        efi_char16_t *variable_name = kmalloc(1024, GFP_KERNEL);
        unsigned long variable_name_size = 1024;

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

        /* Since efi.c happens before procfs is available,
           we create the directory here if it doesn't
           already exist.  There's probably a better way
           to do this.
        */
        if (!efi_dir)
                efi_dir = proc_mkdir("efi", NULL);

        efi_systab_entry = create_proc_entry("systab", S_IRUSR | S_IRGRP, efi_dir);
        if (efi_systab_entry)
                efi_systab_entry->proc_fops = &efi_systab_fops;

        efi_vars_dir = proc_mkdir("vars", efi_dir);

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

        memset(variable_name, 0, 1024);

        do {
                variable_name_size=1024;

                status = efi.get_next_variable(&variable_name_size,
                                               variable_name,
                                               &vendor_guid);


                switch (status) {
                case EFI_SUCCESS:
                        efivar_create_proc_entry(variable_name_size,
                                                 variable_name,
                                                 &vendor_guid);
                        break;
                case EFI_NOT_FOUND:
                        break;
                default:
                        printk(KERN_WARNING "get_next_variable: status=%lx\n", status);
                        status = EFI_NOT_FOUND;
                        break;
                }

        } while (status != EFI_NOT_FOUND);

        kfree(variable_name);
        return 0;
}

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

        spin_lock(&efivars_lock);
        if (efi_systab_entry)
                remove_proc_entry(efi_systab_entry->name, efi_dir);
        list_for_each_safe(pos, n, &efivar_list) {
                efivar = efivar_entry(pos);
                remove_proc_entry(efivar->entry->name, efi_vars_dir);
                list_del(&efivar->list);
                kfree(efivar);
        }
        spin_unlock(&efivars_lock);

        remove_proc_entry(efi_vars_dir->name, efi_dir);
}

module_init(efivars_init);
module_exit(efivars_exit);

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 4
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -4
 * c-argdecl-indent: 4
 * c-label-offset: -4
 * c-continued-statement-offset: 4
 * c-continued-brace-offset: 0
 * indent-tabs-mode: nil
 * tab-width: 8
 * End:
 */