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i8k.c

/*
 * i8k.c -- Linux driver for accessing the SMM BIOS on Dell laptops.
 *        See http://www.debian.org/~dz/i8k/ for more information
 *        and for latest version of this driver.
 *
 * Copyright (C) 2001  Massimo Dal Zotto <dz@debian.org>
 *
 * 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, 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.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/dmi.h>
#include <linux/capability.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#include <linux/i8k.h>

#define I8K_VERSION           "1.14 21/02/2005"

#define I8K_SMM_FN_STATUS     0x0025
#define I8K_SMM_POWER_STATUS  0x0069
#define I8K_SMM_SET_FAN       0x01a3
#define I8K_SMM_GET_FAN       0x00a3
#define I8K_SMM_GET_SPEED     0x02a3
#define I8K_SMM_GET_TEMP      0x10a3
#define I8K_SMM_GET_DELL_SIG1 0xfea3
#define I8K_SMM_GET_DELL_SIG2 0xffa3
#define I8K_SMM_BIOS_VERSION  0x00a6

#define I8K_FAN_MULT          30
#define I8K_MAX_TEMP          127

#define I8K_FN_NONE           0x00
#define I8K_FN_UP       0x01
#define I8K_FN_DOWN           0x02
#define I8K_FN_MUTE           0x04
#define I8K_FN_MASK           0x07
#define I8K_FN_SHIFT          8

#define I8K_POWER_AC          0x05
#define I8K_POWER_BATTERY     0x01

#define I8K_TEMPERATURE_BUG   1

static char bios_version[4];

MODULE_AUTHOR("Massimo Dal Zotto (dz@debian.org)");
MODULE_DESCRIPTION("Driver for accessing SMM BIOS on Dell laptops");
MODULE_LICENSE("GPL");

static int force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force loading without checking for supported models");

static int ignore_dmi;
module_param(ignore_dmi, bool, 0);
MODULE_PARM_DESC(ignore_dmi, "Continue probing hardware even if DMI data does not match");

static int restricted;
module_param(restricted, bool, 0);
MODULE_PARM_DESC(restricted, "Allow fan control if SYS_ADMIN capability set");

static int power_status;
module_param(power_status, bool, 0600);
MODULE_PARM_DESC(power_status, "Report power status in /proc/i8k");

static int i8k_open_fs(struct inode *inode, struct file *file);
static int i8k_ioctl(struct inode *, struct file *, unsigned int,
                 unsigned long);

static const struct file_operations i8k_fops = {
      .open       = i8k_open_fs,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = single_release,
      .ioctl            = i8k_ioctl,
};

struct smm_regs {
      unsigned int eax;
      unsigned int ebx __attribute__ ((packed));
      unsigned int ecx __attribute__ ((packed));
      unsigned int edx __attribute__ ((packed));
      unsigned int esi __attribute__ ((packed));
      unsigned int edi __attribute__ ((packed));
};

static inline const char *i8k_get_dmi_data(int field)
{
      const char *dmi_data = dmi_get_system_info(field);

      return dmi_data && *dmi_data ? dmi_data : "?";
}

/*
 * Call the System Management Mode BIOS. Code provided by Jonathan Buzzard.
 */
static int i8k_smm(struct smm_regs *regs)
{
      int rc;
      int eax = regs->eax;

      asm("pushl %%eax\n\t"
          "movl 0(%%eax),%%edx\n\t"
          "push %%edx\n\t"
          "movl 4(%%eax),%%ebx\n\t"
          "movl 8(%%eax),%%ecx\n\t"
          "movl 12(%%eax),%%edx\n\t"
          "movl 16(%%eax),%%esi\n\t"
          "movl 20(%%eax),%%edi\n\t"
          "popl %%eax\n\t"
          "out %%al,$0xb2\n\t"
          "out %%al,$0x84\n\t"
          "xchgl %%eax,(%%esp)\n\t"
          "movl %%ebx,4(%%eax)\n\t"
          "movl %%ecx,8(%%eax)\n\t"
          "movl %%edx,12(%%eax)\n\t"
          "movl %%esi,16(%%eax)\n\t"
          "movl %%edi,20(%%eax)\n\t"
          "popl %%edx\n\t"
          "movl %%edx,0(%%eax)\n\t"
          "lahf\n\t"
          "shrl $8,%%eax\n\t"
          "andl $1,%%eax\n":"=a"(rc)
          :    "a"(regs)
          :    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");

      if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
            return -EINVAL;

      return 0;
}

/*
 * Read the bios version. Return the version as an integer corresponding
 * to the ascii value, for example "A17" is returned as 0x00413137.
 */
static int i8k_get_bios_version(void)
{
      struct smm_regs regs = { .eax = I8K_SMM_BIOS_VERSION, };

      return i8k_smm(&regs) ? : regs.eax;
}

/*
 * Read the Fn key status.
 */
static int i8k_get_fn_status(void)
{
      struct smm_regs regs = { .eax = I8K_SMM_FN_STATUS, };
      int rc;

      if ((rc = i8k_smm(&regs)) < 0)
            return rc;

      switch ((regs.eax >> I8K_FN_SHIFT) & I8K_FN_MASK) {
      case I8K_FN_UP:
            return I8K_VOL_UP;
      case I8K_FN_DOWN:
            return I8K_VOL_DOWN;
      case I8K_FN_MUTE:
            return I8K_VOL_MUTE;
      default:
            return 0;
      }
}

/*
 * Read the power status.
 */
static int i8k_get_power_status(void)
{
      struct smm_regs regs = { .eax = I8K_SMM_POWER_STATUS, };
      int rc;

      if ((rc = i8k_smm(&regs)) < 0)
            return rc;

      return (regs.eax & 0xff) == I8K_POWER_AC ? I8K_AC : I8K_BATTERY;
}

/*
 * Read the fan status.
 */
static int i8k_get_fan_status(int fan)
{
      struct smm_regs regs = { .eax = I8K_SMM_GET_FAN, };

      regs.ebx = fan & 0xff;
      return i8k_smm(&regs) ? : regs.eax & 0xff;
}

/*
 * Read the fan speed in RPM.
 */
static int i8k_get_fan_speed(int fan)
{
      struct smm_regs regs = { .eax = I8K_SMM_GET_SPEED, };

      regs.ebx = fan & 0xff;
      return i8k_smm(&regs) ? : (regs.eax & 0xffff) * I8K_FAN_MULT;
}

/*
 * Set the fan speed (off, low, high). Returns the new fan status.
 */
static int i8k_set_fan(int fan, int speed)
{
      struct smm_regs regs = { .eax = I8K_SMM_SET_FAN, };

      speed = (speed < 0) ? 0 : ((speed > I8K_FAN_MAX) ? I8K_FAN_MAX : speed);
      regs.ebx = (fan & 0xff) | (speed << 8);

      return i8k_smm(&regs) ? : i8k_get_fan_status(fan);
}

/*
 * Read the cpu temperature.
 */
static int i8k_get_temp(int sensor)
{
      struct smm_regs regs = { .eax = I8K_SMM_GET_TEMP, };
      int rc;
      int temp;

#ifdef I8K_TEMPERATURE_BUG
      static int prev;
#endif
      regs.ebx = sensor & 0xff;
      if ((rc = i8k_smm(&regs)) < 0)
            return rc;

      temp = regs.eax & 0xff;

#ifdef I8K_TEMPERATURE_BUG
      /*
       * Sometimes the temperature sensor returns 0x99, which is out of range.
       * In this case we return (once) the previous cached value. For example:
       # 1003655137 00000058 00005a4b
       # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees
       # 1003655139 00000054 00005c52
       */
      if (temp > I8K_MAX_TEMP) {
            temp = prev;
            prev = I8K_MAX_TEMP;
      } else {
            prev = temp;
      }
#endif

      return temp;
}

static int i8k_get_dell_signature(int req_fn)
{
      struct smm_regs regs = { .eax = req_fn, };
      int rc;

      if ((rc = i8k_smm(&regs)) < 0)
            return rc;

      return regs.eax == 1145651527 && regs.edx == 1145392204 ? 0 : -1;
}

static int i8k_ioctl(struct inode *ip, struct file *fp, unsigned int cmd,
                 unsigned long arg)
{
      int val = 0;
      int speed;
      unsigned char buff[16];
      int __user *argp = (int __user *)arg;

      if (!argp)
            return -EINVAL;

      switch (cmd) {
      case I8K_BIOS_VERSION:
            val = i8k_get_bios_version();
            break;

      case I8K_MACHINE_ID:
            memset(buff, 0, 16);
            strlcpy(buff, i8k_get_dmi_data(DMI_PRODUCT_SERIAL), sizeof(buff));
            break;

      case I8K_FN_STATUS:
            val = i8k_get_fn_status();
            break;

      case I8K_POWER_STATUS:
            val = i8k_get_power_status();
            break;

      case I8K_GET_TEMP:
            val = i8k_get_temp(0);
            break;

      case I8K_GET_SPEED:
            if (copy_from_user(&val, argp, sizeof(int)))
                  return -EFAULT;

            val = i8k_get_fan_speed(val);
            break;

      case I8K_GET_FAN:
            if (copy_from_user(&val, argp, sizeof(int)))
                  return -EFAULT;

            val = i8k_get_fan_status(val);
            break;

      case I8K_SET_FAN:
            if (restricted && !capable(CAP_SYS_ADMIN))
                  return -EPERM;

            if (copy_from_user(&val, argp, sizeof(int)))
                  return -EFAULT;

            if (copy_from_user(&speed, argp + 1, sizeof(int)))
                  return -EFAULT;

            val = i8k_set_fan(val, speed);
            break;

      default:
            return -EINVAL;
      }

      if (val < 0)
            return val;

      switch (cmd) {
      case I8K_BIOS_VERSION:
            if (copy_to_user(argp, &val, 4))
                  return -EFAULT;

            break;
      case I8K_MACHINE_ID:
            if (copy_to_user(argp, buff, 16))
                  return -EFAULT;

            break;
      default:
            if (copy_to_user(argp, &val, sizeof(int)))
                  return -EFAULT;

            break;
      }

      return 0;
}

/*
 * Print the information for /proc/i8k.
 */
static int i8k_proc_show(struct seq_file *seq, void *offset)
{
      int fn_key, cpu_temp, ac_power;
      int left_fan, right_fan, left_speed, right_speed;

      cpu_temp    = i8k_get_temp(0);                  /* 11100 µs */
      left_fan    = i8k_get_fan_status(I8K_FAN_LEFT); /*   580 µs */
      right_fan   = i8k_get_fan_status(I8K_FAN_RIGHT);      /*   580 µs */
      left_speed  = i8k_get_fan_speed(I8K_FAN_LEFT);  /*   580 µs */
      right_speed = i8k_get_fan_speed(I8K_FAN_RIGHT); /*   580 µs */
      fn_key            = i8k_get_fn_status();              /*   750 µs */
      if (power_status)
            ac_power = i8k_get_power_status();        /* 14700 µs */
      else
            ac_power = -1;

      /*
       * Info:
       *
       * 1)  Format version (this will change if format changes)
       * 2)  BIOS version
       * 3)  BIOS machine ID
       * 4)  Cpu temperature
       * 5)  Left fan status
       * 6)  Right fan status
       * 7)  Left fan speed
       * 8)  Right fan speed
       * 9)  AC power
       * 10) Fn Key status
       */
      return seq_printf(seq, "%s %s %s %d %d %d %d %d %d %d\n",
                    I8K_PROC_FMT,
                    bios_version,
                    i8k_get_dmi_data(DMI_PRODUCT_SERIAL),
                    cpu_temp,
                    left_fan, right_fan, left_speed, right_speed,
                    ac_power, fn_key);
}

static int i8k_open_fs(struct inode *inode, struct file *file)
{
      return single_open(file, i8k_proc_show, NULL);
}

static struct dmi_system_id __initdata i8k_dmi_table[] = {
      {
            .ident = "Dell Inspiron",
            .matches = {
                  DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
                  DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
            },
      },
      {
            .ident = "Dell Latitude",
            .matches = {
                  DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
                  DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
            },
      },
      {
            .ident = "Dell Inspiron 2",
            .matches = {
                  DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                  DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
            },
      },
      {
            .ident = "Dell Latitude 2",
            .matches = {
                  DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                  DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
            },
      },
      { }
};

/*
 * Probe for the presence of a supported laptop.
 */
static int __init i8k_probe(void)
{
      char buff[4];
      int version;

      /*
       * Get DMI information
       */
      if (!dmi_check_system(i8k_dmi_table)) {
            if (!ignore_dmi && !force)
                  return -ENODEV;

            printk(KERN_INFO "i8k: not running on a supported Dell system.\n");
            printk(KERN_INFO "i8k: vendor=%s, model=%s, version=%s\n",
                  i8k_get_dmi_data(DMI_SYS_VENDOR),
                  i8k_get_dmi_data(DMI_PRODUCT_NAME),
                  i8k_get_dmi_data(DMI_BIOS_VERSION));
      }

      strlcpy(bios_version, i8k_get_dmi_data(DMI_BIOS_VERSION), sizeof(bios_version));

      /*
       * Get SMM Dell signature
       */
      if (i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG1) &&
          i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG2)) {
            printk(KERN_ERR "i8k: unable to get SMM Dell signature\n");
            if (!force)
                  return -ENODEV;
      }

      /*
       * Get SMM BIOS version.
       */
      version = i8k_get_bios_version();
      if (version <= 0) {
            printk(KERN_WARNING "i8k: unable to get SMM BIOS version\n");
      } else {
            buff[0] = (version >> 16) & 0xff;
            buff[1] = (version >> 8) & 0xff;
            buff[2] = (version) & 0xff;
            buff[3] = '\0';
            /*
             * If DMI BIOS version is unknown use SMM BIOS version.
             */
            if (!dmi_get_system_info(DMI_BIOS_VERSION))
                  strlcpy(bios_version, buff, sizeof(bios_version));

            /*
             * Check if the two versions match.
             */
            if (strncmp(buff, bios_version, sizeof(bios_version)) != 0)
                  printk(KERN_WARNING "i8k: BIOS version mismatch: %s != %s\n",
                        buff, bios_version);
      }

      return 0;
}

static int __init i8k_init(void)
{
      struct proc_dir_entry *proc_i8k;

      /* Are we running on an supported laptop? */
      if (i8k_probe())
            return -ENODEV;

      /* Register the proc entry */
      proc_i8k = create_proc_entry("i8k", 0, NULL);
      if (!proc_i8k)
            return -ENOENT;

      proc_i8k->proc_fops = &i8k_fops;
      proc_i8k->owner = THIS_MODULE;

      printk(KERN_INFO
             "Dell laptop SMM driver v%s Massimo Dal Zotto (dz@debian.org)\n",
             I8K_VERSION);

      return 0;
}

static void __exit i8k_exit(void)
{
      remove_proc_entry("i8k", NULL);
}

module_init(i8k_init);
module_exit(i8k_exit);

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