drivers/char/i8k.c - pub/scm/linux/kernel/git/jhogan/linux - Git at Google

 /*
  * 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 <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 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 char *i8k_get_dmi_data(int field)
 {
 	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);
	/*
	* 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 <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 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 char *i8k_get_dmi_data(int field)
	{
	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);