drivers/char/i8k.c - kernel/msm-4.9 - Gitiles

 /*
  * i8k.c -- Linux driver for accessing the SMM BIOS on Dell laptops.
  *
  * Copyright (C) 2001  Massimo Dal Zotto <dz@debian.org>
  *
  * Hwmon integration:
  * Copyright (C) 2011  Jean Delvare <jdelvare@suse.de>
  * Copyright (C) 2013  Guenter Roeck <linux@roeck-us.net>
  *
  * 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.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #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 <linux/mutex.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/sched.h>

 #include <linux/i8k.h>

 #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_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 DEFINE_MUTEX(i8k_mutex);
 static char bios_version[4];
 static struct device *i8k_hwmon_dev;
 static u32 i8k_hwmon_flags;
 static int i8k_fan_mult;
 static int i8k_pwm_mult;
 static int i8k_fan_max = I8K_FAN_HIGH;

 #define I8K_HWMON_HAVE_TEMP1	(1 << 0)
 #define I8K_HWMON_HAVE_TEMP2	(1 << 1)
 #define I8K_HWMON_HAVE_TEMP3	(1 << 2)
 #define I8K_HWMON_HAVE_TEMP4	(1 << 3)
 #define I8K_HWMON_HAVE_FAN1	(1 << 4)
 #define I8K_HWMON_HAVE_FAN2	(1 << 5)

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

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

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

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

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

 static int fan_mult = I8K_FAN_MULT;
 module_param(fan_mult, int, 0);
 MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with");

 static int fan_max = I8K_FAN_HIGH;
 module_param(fan_max, int, 0);
 MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed");

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

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

 struct smm_regs {
 	unsigned int eax;
 	unsigned int ebx __packed;
 	unsigned int ecx __packed;
 	unsigned int edx __packed;
 	unsigned int esi __packed;
 	unsigned int edi __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;
 	cpumask_var_t old_mask;

 	/* SMM requires CPU 0 */
 	if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
 		return -ENOMEM;
 	cpumask_copy(old_mask, &current->cpus_allowed);
 	rc = set_cpus_allowed_ptr(current, cpumask_of(0));
 	if (rc)
 		goto out;
 	if (smp_processor_id() != 0) {
 		rc = -EBUSY;
 		goto out;
 	}

 #if defined(CONFIG_X86_64)
 	asm volatile("pushq %%rax\n\t"
 		"movl 0(%%rax),%%edx\n\t"
 		"pushq %%rdx\n\t"
 		"movl 4(%%rax),%%ebx\n\t"
 		"movl 8(%%rax),%%ecx\n\t"
 		"movl 12(%%rax),%%edx\n\t"
 		"movl 16(%%rax),%%esi\n\t"
 		"movl 20(%%rax),%%edi\n\t"
 		"popq %%rax\n\t"
 		"out %%al,$0xb2\n\t"
 		"out %%al,$0x84\n\t"
 		"xchgq %%rax,(%%rsp)\n\t"
 		"movl %%ebx,4(%%rax)\n\t"
 		"movl %%ecx,8(%%rax)\n\t"
 		"movl %%edx,12(%%rax)\n\t"
 		"movl %%esi,16(%%rax)\n\t"
 		"movl %%edi,20(%%rax)\n\t"
 		"popq %%rdx\n\t"
 		"movl %%edx,0(%%rax)\n\t"
 		"pushfq\n\t"
 		"popq %%rax\n\t"
 		"andl $1,%%eax\n"
 		: "=a"(rc)
 		:    "a"(regs)
 		:    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
 #else
 	asm volatile("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");
 #endif
 	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
 		rc = -EINVAL;

 out:
 	set_cpus_allowed_ptr(current, old_mask);
 	free_cpumask_var(old_mask);
 	return rc;
 }

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

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

 	rc = i8k_smm(&regs);
 	if (rc < 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[4] = { I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1 };
 #endif
 	regs.ebx = sensor & 0xff;
 	rc = i8k_smm(&regs);
 	if (rc < 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[sensor];
 		prev[sensor] = I8K_MAX_TEMP+1;
 	} else {
 		prev[sensor] = temp;
 	}
 	if (temp > I8K_MAX_TEMP)
 		return -ERANGE;
 #endif

 	return temp;
 }

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

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

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

 static int
 i8k_ioctl_unlocked(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 = (bios_version[0] << 16) |
 				(bios_version[1] << 8) | bios_version[2];
 		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;
 }

 static long i8k_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 {
 	long ret;

 	mutex_lock(&i8k_mutex);
 	ret = i8k_ioctl_unlocked(fp, cmd, arg);
 	mutex_unlock(&i8k_mutex);

 	return ret;
 }

 /*
  * 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);
 }


 /*
  * Hwmon interface
  */

 static ssize_t i8k_hwmon_show_temp(struct device *dev,
 				   struct device_attribute *devattr,
 				   char *buf)
 {
 	int index = to_sensor_dev_attr(devattr)->index;
 	int temp;

 	temp = i8k_get_temp(index);
 	if (temp == -ERANGE)
 		return -EINVAL;
 	if (temp < 0)
 		return temp;
 	return sprintf(buf, "%d\n", temp * 1000);
 }

 static ssize_t i8k_hwmon_show_fan(struct device *dev,
 				  struct device_attribute *devattr,
 				  char *buf)
 {
 	int index = to_sensor_dev_attr(devattr)->index;
 	int fan_speed;

 	fan_speed = i8k_get_fan_speed(index);
 	if (fan_speed < 0)
 		return fan_speed;
 	return sprintf(buf, "%d\n", fan_speed);
 }

 static ssize_t i8k_hwmon_show_pwm(struct device *dev,
 				  struct device_attribute *devattr,
 				  char *buf)
 {
 	int index = to_sensor_dev_attr(devattr)->index;
 	int status;

 	status = i8k_get_fan_status(index);
 	if (status < 0)
 		return -EIO;
 	return sprintf(buf, "%d\n", clamp_val(status * i8k_pwm_mult, 0, 255));
 }

 static ssize_t i8k_hwmon_set_pwm(struct device *dev,
 				 struct device_attribute *attr,
 				 const char *buf, size_t count)
 {
 	int index = to_sensor_dev_attr(attr)->index;
 	unsigned long val;
 	int err;

 	err = kstrtoul(buf, 10, &val);
 	if (err)
 		return err;
 	val = clamp_val(DIV_ROUND_CLOSEST(val, i8k_pwm_mult), 0, i8k_fan_max);

 	mutex_lock(&i8k_mutex);
 	err = i8k_set_fan(index, val);
 	mutex_unlock(&i8k_mutex);

 	return err < 0 ? -EIO : count;
 }

 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 1);
 static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 2);
 static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 3);
 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
 			  I8K_FAN_LEFT);
 static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, i8k_hwmon_show_pwm,
 			  i8k_hwmon_set_pwm, I8K_FAN_LEFT);
 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
 			  I8K_FAN_RIGHT);
 static SENSOR_DEVICE_ATTR(pwm2, S_IRUGO | S_IWUSR, i8k_hwmon_show_pwm,
 			  i8k_hwmon_set_pwm, I8K_FAN_RIGHT);

 static struct attribute *i8k_attrs[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,	/* 0 */
 	&sensor_dev_attr_temp2_input.dev_attr.attr,	/* 1 */
 	&sensor_dev_attr_temp3_input.dev_attr.attr,	/* 2 */
 	&sensor_dev_attr_temp4_input.dev_attr.attr,	/* 3 */
 	&sensor_dev_attr_fan1_input.dev_attr.attr,	/* 4 */
 	&sensor_dev_attr_pwm1.dev_attr.attr,		/* 5 */
 	&sensor_dev_attr_fan2_input.dev_attr.attr,	/* 6 */
 	&sensor_dev_attr_pwm2.dev_attr.attr,		/* 7 */
 	NULL
 };

 static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,
 			      int index)
 {
 	if (index == 0 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))
 		return 0;
 	if (index == 1 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP2))
 		return 0;
 	if (index == 2 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP3))
 		return 0;
 	if (index == 3 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP4))
 		return 0;
 	if (index >= 4 && index <= 5 &&
 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1))
 		return 0;
 	if (index >= 6 && index <= 7 &&
 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN2))
 		return 0;

 	return attr->mode;
 }

 static const struct attribute_group i8k_group = {
 	.attrs = i8k_attrs,
 	.is_visible = i8k_is_visible,
 };
 __ATTRIBUTE_GROUPS(i8k);

 static int __init i8k_init_hwmon(void)
 {
 	int err;

 	i8k_hwmon_flags = 0;

 	/* CPU temperature attributes, if temperature reading is OK */
 	err = i8k_get_temp(0);
 	if (err >= 0 || err == -ERANGE)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
 	/* check for additional temperature sensors */
 	err = i8k_get_temp(1);
 	if (err >= 0 || err == -ERANGE)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
 	err = i8k_get_temp(2);
 	if (err >= 0 || err == -ERANGE)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
 	err = i8k_get_temp(3);
 	if (err >= 0 || err == -ERANGE)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;

 	/* Left fan attributes, if left fan is present */
 	err = i8k_get_fan_status(I8K_FAN_LEFT);
 	if (err >= 0)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1;

 	/* Right fan attributes, if right fan is present */
 	err = i8k_get_fan_status(I8K_FAN_RIGHT);
 	if (err >= 0)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;

 	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "i8k", NULL,
 							  i8k_groups);
 	if (IS_ERR(i8k_hwmon_dev)) {
 		err = PTR_ERR(i8k_hwmon_dev);
 		i8k_hwmon_dev = NULL;
 		pr_err("hwmon registration failed (%d)\n", err);
 		return err;
 	}
 	return 0;
 }

 struct i8k_config_data {
 	int fan_mult;
 	int fan_max;
 };

 enum i8k_configs {
 	DELL_LATITUDE_D520,
 	DELL_LATITUDE_E6540,
 	DELL_PRECISION_490,
 	DELL_STUDIO,
 	DELL_XPS_M140,
 };

 static const struct i8k_config_data i8k_config_data[] = {
 	[DELL_LATITUDE_D520] = {
 		.fan_mult = 1,
 		.fan_max = I8K_FAN_TURBO,
 	},
 	[DELL_LATITUDE_E6540] = {
 		.fan_mult = 1,
 		.fan_max = I8K_FAN_HIGH,
 	},
 	[DELL_PRECISION_490] = {
 		.fan_mult = 1,
 		.fan_max = I8K_FAN_TURBO,
 	},
 	[DELL_STUDIO] = {
 		.fan_mult = 1,
 		.fan_max = I8K_FAN_HIGH,
 	},
 	[DELL_XPS_M140] = {
 		.fan_mult = 1,
 		.fan_max = I8K_FAN_HIGH,
 	},
 };

 static struct dmi_system_id i8k_dmi_table[] __initdata = {
 	{
 		.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 D520",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude D520"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_D520],
 	},
 	{
 		.ident = "Dell Latitude E6440",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6440"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_E6540],
 	},
 	{
 		.ident = "Dell Latitude E6540",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6540"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_E6540],
 	},
 	{
 		.ident = "Dell Latitude 2",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
 		},
 	},
 	{	/* UK Inspiron 6400  */
 		.ident = "Dell Inspiron 3",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "MM061"),
 		},
 	},
 	{
 		.ident = "Dell Inspiron 3",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "MP061"),
 		},
 	},
 	{
 		.ident = "Dell Precision 490",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME,
 				  "Precision WorkStation 490"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_PRECISION_490],
 	},
 	{
 		.ident = "Dell Precision",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Precision"),
 		},
 	},
 	{
 		.ident = "Dell Vostro",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Vostro"),
 		},
 	},
 	{
 		.ident = "Dell XPS421",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
 		},
 	},
 	{
 		.ident = "Dell Studio",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Studio"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_STUDIO],
 	},
 	{
 		.ident = "Dell XPS M140",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "MXC051"),
 		},
 		.driver_data = (void *)&i8k_config_data[DELL_XPS_M140],
 	},
 	{ }
 };

 MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);

 /*
  * Probe for the presence of a supported laptop.
  */
 static int __init i8k_probe(void)
 {
 	const struct dmi_system_id *id;

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

 		pr_info("not running on a supported Dell system.\n");
 		pr_info("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)) {
 		pr_err("unable to get SMM Dell signature\n");
 		if (!force)
 			return -ENODEV;
 	}

 	i8k_fan_mult = fan_mult;
 	i8k_fan_max = fan_max ? : I8K_FAN_HIGH;	/* Must not be 0 */
 	id = dmi_first_match(i8k_dmi_table);
 	if (id && id->driver_data) {
 		const struct i8k_config_data *conf = id->driver_data;

 		if (fan_mult == I8K_FAN_MULT && conf->fan_mult)
 			i8k_fan_mult = conf->fan_mult;
 		if (fan_max == I8K_FAN_HIGH && conf->fan_max)
 			i8k_fan_max = conf->fan_max;
 	}
 	i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);

 	return 0;
 }

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

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

 	/* Register the proc entry */
 	proc_i8k = proc_create("i8k", 0, NULL, &i8k_fops);
 	if (!proc_i8k)
 		return -ENOENT;

 	err = i8k_init_hwmon();
 	if (err)
 		goto exit_remove_proc;

 	return 0;

  exit_remove_proc:
 	remove_proc_entry("i8k", NULL);
 	return err;
 }

 static void __exit i8k_exit(void)
 {
 	hwmon_device_unregister(i8k_hwmon_dev);
 	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.
	*
	* Copyright (C) 2001 Massimo Dal Zotto <dz@debian.org>
	*
	* Hwmon integration:
	* Copyright (C) 2011 Jean Delvare <jdelvare@suse.de>
	* Copyright (C) 2013 Guenter Roeck <linux@roeck-us.net>
	*
	* 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.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#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 <linux/mutex.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/uaccess.h>
	#include <linux/io.h>
	#include <linux/sched.h>

	#include <linux/i8k.h>

	#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_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 DEFINE_MUTEX(i8k_mutex);
	static char bios_version[4];
	static struct device *i8k_hwmon_dev;
	static u32 i8k_hwmon_flags;
	static int i8k_fan_mult;
	static int i8k_pwm_mult;
	static int i8k_fan_max = I8K_FAN_HIGH;

	#define I8K_HWMON_HAVE_TEMP1 (1 << 0)
	#define I8K_HWMON_HAVE_TEMP2 (1 << 1)
	#define I8K_HWMON_HAVE_TEMP3 (1 << 2)
	#define I8K_HWMON_HAVE_TEMP4 (1 << 3)
	#define I8K_HWMON_HAVE_FAN1 (1 << 4)
	#define I8K_HWMON_HAVE_FAN2 (1 << 5)

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

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

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

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

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

	static int fan_mult = I8K_FAN_MULT;
	module_param(fan_mult, int, 0);
	MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with");

	static int fan_max = I8K_FAN_HIGH;
	module_param(fan_max, int, 0);
	MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed");

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

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

	struct smm_regs {
	unsigned int eax;
	unsigned int ebx __packed;
	unsigned int ecx __packed;
	unsigned int edx __packed;
	unsigned int esi __packed;
	unsigned int edi __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;
	cpumask_var_t old_mask;

	/* SMM requires CPU 0 */
	if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
	return -ENOMEM;
	cpumask_copy(old_mask, &current->cpus_allowed);
	rc = set_cpus_allowed_ptr(current, cpumask_of(0));
	if (rc)
	goto out;
	if (smp_processor_id() != 0) {
	rc = -EBUSY;
	goto out;
	}

	#if defined(CONFIG_X86_64)
	asm volatile("pushq %%rax\n\t"
	"movl 0(%%rax),%%edx\n\t"
	"pushq %%rdx\n\t"
	"movl 4(%%rax),%%ebx\n\t"
	"movl 8(%%rax),%%ecx\n\t"
	"movl 12(%%rax),%%edx\n\t"
	"movl 16(%%rax),%%esi\n\t"
	"movl 20(%%rax),%%edi\n\t"
	"popq %%rax\n\t"
	"out %%al,$0xb2\n\t"
	"out %%al,$0x84\n\t"
	"xchgq %%rax,(%%rsp)\n\t"
	"movl %%ebx,4(%%rax)\n\t"
	"movl %%ecx,8(%%rax)\n\t"
	"movl %%edx,12(%%rax)\n\t"
	"movl %%esi,16(%%rax)\n\t"
	"movl %%edi,20(%%rax)\n\t"
	"popq %%rdx\n\t"
	"movl %%edx,0(%%rax)\n\t"
	"pushfq\n\t"
	"popq %%rax\n\t"
	"andl $1,%%eax\n"
	: "=a"(rc)
	: "a"(regs)
	: "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
	#else
	asm volatile("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");
	#endif
	if (rc != 0 \|\| (regs->eax & 0xffff) == 0xffff \|\| regs->eax == eax)
	rc = -EINVAL;

	out:
	set_cpus_allowed_ptr(current, old_mask);
	free_cpumask_var(old_mask);
	return rc;
	}

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

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

	rc = i8k_smm(&regs);
	if (rc < 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[4] = { I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1 };
	#endif
	regs.ebx = sensor & 0xff;
	rc = i8k_smm(&regs);
	if (rc < 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[sensor];
	prev[sensor] = I8K_MAX_TEMP+1;
	} else {
	prev[sensor] = temp;
	}
	if (temp > I8K_MAX_TEMP)
	return -ERANGE;
	#endif

	return temp;
	}

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

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

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

	static int
	i8k_ioctl_unlocked(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 = (bios_version[0] << 16) \|
	(bios_version[1] << 8) \| bios_version[2];
	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;
	}

	static long i8k_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
	{
	long ret;

	mutex_lock(&i8k_mutex);
	ret = i8k_ioctl_unlocked(fp, cmd, arg);
	mutex_unlock(&i8k_mutex);

	return ret;
	}

	/*
	* 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);
	}


	/*
	* Hwmon interface
	*/

	static ssize_t i8k_hwmon_show_temp(struct device *dev,
	struct device_attribute *devattr,
	char *buf)
	{
	int index = to_sensor_dev_attr(devattr)->index;
	int temp;

	temp = i8k_get_temp(index);
	if (temp == -ERANGE)
	return -EINVAL;
	if (temp < 0)
	return temp;
	return sprintf(buf, "%d\n", temp * 1000);
	}

	static ssize_t i8k_hwmon_show_fan(struct device *dev,
	struct device_attribute *devattr,
	char *buf)
	{
	int index = to_sensor_dev_attr(devattr)->index;
	int fan_speed;

	fan_speed = i8k_get_fan_speed(index);
	if (fan_speed < 0)
	return fan_speed;
	return sprintf(buf, "%d\n", fan_speed);
	}

	static ssize_t i8k_hwmon_show_pwm(struct device *dev,
	struct device_attribute *devattr,
	char *buf)
	{
	int index = to_sensor_dev_attr(devattr)->index;
	int status;

	status = i8k_get_fan_status(index);
	if (status < 0)
	return -EIO;
	return sprintf(buf, "%d\n", clamp_val(status * i8k_pwm_mult, 0, 255));
	}

	static ssize_t i8k_hwmon_set_pwm(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	int index = to_sensor_dev_attr(attr)->index;
	unsigned long val;
	int err;

	err = kstrtoul(buf, 10, &val);
	if (err)
	return err;
	val = clamp_val(DIV_ROUND_CLOSEST(val, i8k_pwm_mult), 0, i8k_fan_max);

	mutex_lock(&i8k_mutex);
	err = i8k_set_fan(index, val);
	mutex_unlock(&i8k_mutex);

	return err < 0 ? -EIO : count;
	}

	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 0);
	static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 1);
	static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 2);
	static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 3);
	static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
	I8K_FAN_LEFT);
	static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO \| S_IWUSR, i8k_hwmon_show_pwm,
	i8k_hwmon_set_pwm, I8K_FAN_LEFT);
	static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
	I8K_FAN_RIGHT);
	static SENSOR_DEVICE_ATTR(pwm2, S_IRUGO \| S_IWUSR, i8k_hwmon_show_pwm,
	i8k_hwmon_set_pwm, I8K_FAN_RIGHT);

	static struct attribute *i8k_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr, /* 0 */
	&sensor_dev_attr_temp2_input.dev_attr.attr, /* 1 */
	&sensor_dev_attr_temp3_input.dev_attr.attr, /* 2 */
	&sensor_dev_attr_temp4_input.dev_attr.attr, /* 3 */
	&sensor_dev_attr_fan1_input.dev_attr.attr, /* 4 */
	&sensor_dev_attr_pwm1.dev_attr.attr, /* 5 */
	&sensor_dev_attr_fan2_input.dev_attr.attr, /* 6 */
	&sensor_dev_attr_pwm2.dev_attr.attr, /* 7 */
	NULL
	};

	static umode_t i8k_is_visible(struct kobject kobj, struct attribute attr,
	int index)
	{
	if (index == 0 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))
	return 0;
	if (index == 1 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP2))
	return 0;
	if (index == 2 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP3))
	return 0;
	if (index == 3 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP4))
	return 0;
	if (index >= 4 && index <= 5 &&
	!(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1))
	return 0;
	if (index >= 6 && index <= 7 &&
	!(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN2))
	return 0;

	return attr->mode;
	}

	static const struct attribute_group i8k_group = {
	.attrs = i8k_attrs,
	.is_visible = i8k_is_visible,
	};
	__ATTRIBUTE_GROUPS(i8k);

	static int __init i8k_init_hwmon(void)
	{
	int err;

	i8k_hwmon_flags = 0;

	/* CPU temperature attributes, if temperature reading is OK */
	err = i8k_get_temp(0);
	if (err >= 0 \|\| err == -ERANGE)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_TEMP1;
	/* check for additional temperature sensors */
	err = i8k_get_temp(1);
	if (err >= 0 \|\| err == -ERANGE)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_TEMP2;
	err = i8k_get_temp(2);
	if (err >= 0 \|\| err == -ERANGE)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_TEMP3;
	err = i8k_get_temp(3);
	if (err >= 0 \|\| err == -ERANGE)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_TEMP4;

	/* Left fan attributes, if left fan is present */
	err = i8k_get_fan_status(I8K_FAN_LEFT);
	if (err >= 0)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_FAN1;

	/* Right fan attributes, if right fan is present */
	err = i8k_get_fan_status(I8K_FAN_RIGHT);
	if (err >= 0)
	i8k_hwmon_flags \|= I8K_HWMON_HAVE_FAN2;

	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "i8k", NULL,
	i8k_groups);
	if (IS_ERR(i8k_hwmon_dev)) {
	err = PTR_ERR(i8k_hwmon_dev);
	i8k_hwmon_dev = NULL;
	pr_err("hwmon registration failed (%d)\n", err);
	return err;
	}
	return 0;
	}

	struct i8k_config_data {
	int fan_mult;
	int fan_max;
	};

	enum i8k_configs {
	DELL_LATITUDE_D520,
	DELL_LATITUDE_E6540,
	DELL_PRECISION_490,
	DELL_STUDIO,
	DELL_XPS_M140,
	};

	static const struct i8k_config_data i8k_config_data[] = {
	[DELL_LATITUDE_D520] = {
	.fan_mult = 1,
	.fan_max = I8K_FAN_TURBO,
	},
	[DELL_LATITUDE_E6540] = {
	.fan_mult = 1,
	.fan_max = I8K_FAN_HIGH,
	},
	[DELL_PRECISION_490] = {
	.fan_mult = 1,
	.fan_max = I8K_FAN_TURBO,
	},
	[DELL_STUDIO] = {
	.fan_mult = 1,
	.fan_max = I8K_FAN_HIGH,
	},
	[DELL_XPS_M140] = {
	.fan_mult = 1,
	.fan_max = I8K_FAN_HIGH,
	},
	};

	static struct dmi_system_id i8k_dmi_table[] __initdata = {
	{
	.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 D520",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Latitude D520"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_D520],
	},
	{
	.ident = "Dell Latitude E6440",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6440"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_E6540],
	},
	{
	.ident = "Dell Latitude E6540",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6540"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_E6540],
	},
	{
	.ident = "Dell Latitude 2",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
	},
	},
	{ /* UK Inspiron 6400 */
	.ident = "Dell Inspiron 3",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "MM061"),
	},
	},
	{
	.ident = "Dell Inspiron 3",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "MP061"),
	},
	},
	{
	.ident = "Dell Precision 490",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME,
	"Precision WorkStation 490"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_PRECISION_490],
	},
	{
	.ident = "Dell Precision",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Precision"),
	},
	},
	{
	.ident = "Dell Vostro",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Vostro"),
	},
	},
	{
	.ident = "Dell XPS421",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
	},
	},
	{
	.ident = "Dell Studio",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "Studio"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_STUDIO],
	},
	{
	.ident = "Dell XPS M140",
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
	DMI_MATCH(DMI_PRODUCT_NAME, "MXC051"),
	},
	.driver_data = (void *)&i8k_config_data[DELL_XPS_M140],
	},
	{ }
	};

	MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);

	/*
	* Probe for the presence of a supported laptop.
	*/
	static int __init i8k_probe(void)
	{
	const struct dmi_system_id *id;

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

	pr_info("not running on a supported Dell system.\n");
	pr_info("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)) {
	pr_err("unable to get SMM Dell signature\n");
	if (!force)
	return -ENODEV;
	}

	i8k_fan_mult = fan_mult;
	i8k_fan_max = fan_max ? : I8K_FAN_HIGH; /* Must not be 0 */
	id = dmi_first_match(i8k_dmi_table);
	if (id && id->driver_data) {
	const struct i8k_config_data *conf = id->driver_data;

	if (fan_mult == I8K_FAN_MULT && conf->fan_mult)
	i8k_fan_mult = conf->fan_mult;
	if (fan_max == I8K_FAN_HIGH && conf->fan_max)
	i8k_fan_max = conf->fan_max;
	}
	i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);

	return 0;
	}

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

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

	/* Register the proc entry */
	proc_i8k = proc_create("i8k", 0, NULL, &i8k_fops);
	if (!proc_i8k)
	return -ENOENT;

	err = i8k_init_hwmon();
	if (err)
	goto exit_remove_proc;

	return 0;

	exit_remove_proc:
	remove_proc_entry("i8k", NULL);
	return err;
	}

	static void __exit i8k_exit(void)
	{
	hwmon_device_unregister(i8k_hwmon_dev);
	remove_proc_entry("i8k", NULL);
	}

	module_init(i8k_init);
	module_exit(i8k_exit);