hwmon: Rename i8k driver to dell-smm-hwmon and move it to hwmon tree

This commit moves i8k driver to hwmon tree under name dell-smm-hwmon which is
better name then abbreviation i8k. For backward compatibility is added macro
MODULE_ALIAS("i8k") so modprobe will load driver also old name i8k. CONFIG_I8K
compile option was not changed.

This commit also adds me as maintainer of this new dell-smm-hwmon driver and
remove Guenter Roeck from list who is implicit maintainer all hwmon drivers.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1009 insertions, 0 deletions

diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
new file mode 100644
index 000000000000..65d314b0f197
--- /dev/null
+++ b/drivers/hwmon/dell-smm-hwmon.c
@@ -0,0 +1,1009 @@
+/*
+ * dell-smm-hwmon.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, 2014  Guenter Roeck <linux@roeck-us.net>
+ * Copyright (C) 2014, 2015  Pali Rohár <pali.rohar@gmail.com>
+ *
+ * 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/delay.h>
+#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_FAN_TYPE	0x03a3
+#define I8K_SMM_GET_NOM_SPEED	0x04a3
+#define I8K_SMM_GET_TEMP	0x10a3
+#define I8K_SMM_GET_TEMP_TYPE	0x11a3
+#define I8K_SMM_GET_DELL_SIG1	0xfea3
+#define I8K_SMM_GET_DELL_SIG2	0xffa3
+
+#define I8K_FAN_MULT		30
+#define I8K_FAN_MAX_RPM		30000
+#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
+
+static DEFINE_MUTEX(i8k_mutex);
+static char bios_version[4];
+static struct device *i8k_hwmon_dev;
+static u32 i8k_hwmon_flags;
+static uint i8k_fan_mult = I8K_FAN_MULT;
+static uint i8k_pwm_mult;
+static uint 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_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_DESCRIPTION("Driver for accessing SMM BIOS on Dell laptops");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("i8k");
+
+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 uint fan_mult;
+module_param(fan_mult, uint, 0);
+MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with (default: autodetect)");
+
+static uint fan_max;
+module_param(fan_max, uint, 0);
+MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)");
+
+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;
+}
+
+/*
+ * Read the fan type.
+ */
+static int i8k_get_fan_type(int fan)
+{
+	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, };
+
+	regs.ebx = fan & 0xff;
+	return i8k_smm(&regs) ? : regs.eax & 0xff;
+}
+
+/*
+ * Read the fan nominal rpm for specific fan speed.
+ */
+static int i8k_get_fan_nominal_speed(int fan, int speed)
+{
+	struct smm_regs regs = { .eax = I8K_SMM_GET_NOM_SPEED, };
+
+	regs.ebx = (fan & 0xff) | (speed << 8);
+	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);
+}
+
+static int i8k_get_temp_type(int sensor)
+{
+	struct smm_regs regs = { .eax = I8K_SMM_GET_TEMP_TYPE, };
+
+	regs.ebx = sensor & 0xff;
+	return i8k_smm(&regs) ? : regs.eax & 0xff;
+}
+
+/*
+ * Read the cpu temperature.
+ */
+static int _i8k_get_temp(int sensor)
+{
+	struct smm_regs regs = {
+		.eax = I8K_SMM_GET_TEMP,
+		.ebx = sensor & 0xff,
+	};
+
+	return i8k_smm(&regs) ? : regs.eax & 0xff;
+}
+
+static int i8k_get_temp(int sensor)
+{
+	int temp = _i8k_get_temp(sensor);
+
+	/*
+	 * Sometimes the temperature sensor returns 0x99, which is out of range.
+	 * In this case we retry (once) before returning an error.
+	 # 1003655137 00000058 00005a4b
+	 # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees
+	 # 1003655139 00000054 00005c52
+	 */
+	if (temp == 0x99) {
+		msleep(100);
+		temp = _i8k_get_temp(sensor);
+	}
+	/*
+	 * Return -ENODATA for all invalid temperatures.
+	 *
+	 * Known instances are the 0x99 value as seen above as well as
+	 * 0xc1 (193), which may be returned when trying to read the GPU
+	 * temperature if the system supports a GPU and it is currently
+	 * turned off.
+	 */
+	if (temp > I8K_MAX_TEMP)
+		return -ENODATA;
+
+	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
+	 */
+	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);
+
+	return 0;
+}
+
+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_label(struct device *dev,
+					 struct device_attribute *devattr,
+					 char *buf)
+{
+	static const char * const labels[] = {
+		"CPU",
+		"GPU",
+		"SODIMM",
+		"Other",
+		"Ambient",
+		"Other",
+	};
+	int index = to_sensor_dev_attr(devattr)->index;
+	int type;
+
+	type = i8k_get_temp_type(index);
+	if (type < 0)
+		return type;
+	if (type >= ARRAY_SIZE(labels))
+		type = ARRAY_SIZE(labels) - 1;
+	return sprintf(buf, "%s\n", labels[type]);
+}
+
+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 < 0)
+		return temp;
+	return sprintf(buf, "%d\n", temp * 1000);
+}
+
+static ssize_t i8k_hwmon_show_fan_label(struct device *dev,
+					struct device_attribute *devattr,
+					char *buf)
+{
+	static const char * const labels[] = {
+		"Processor Fan",
+		"Motherboard Fan",
+		"Video Fan",
+		"Power Supply Fan",
+		"Chipset Fan",
+		"Other Fan",
+	};
+	int index = to_sensor_dev_attr(devattr)->index;
+	bool dock = false;
+	int type;
+
+	type = i8k_get_fan_type(index);
+	if (type < 0)
+		return type;
+
+	if (type & 0x10) {
+		dock = true;
+		type &= 0x0F;
+	}
+
+	if (type >= ARRAY_SIZE(labels))
+		type = (ARRAY_SIZE(labels) - 1);
+
+	return sprintf(buf, "%s%s\n", (dock ? "Docking " : ""), labels[type]);
+}
+
+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(temp1_label, S_IRUGO, i8k_hwmon_show_temp_label, NULL,
+			  0);
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp2_label, S_IRUGO, i8k_hwmon_show_temp_label, NULL,
+			  1);
+static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp3_label, S_IRUGO, i8k_hwmon_show_temp_label, NULL,
+			  2);
+static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp4_label, S_IRUGO, i8k_hwmon_show_temp_label, NULL,
+			  3);
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, i8k_hwmon_show_fan, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, i8k_hwmon_show_fan_label, NULL,
+			  0);
+static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, i8k_hwmon_show_pwm,
+			  i8k_hwmon_set_pwm, 0);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
+			  1);
+static SENSOR_DEVICE_ATTR(fan2_label, S_IRUGO, i8k_hwmon_show_fan_label, NULL,
+			  1);
+static SENSOR_DEVICE_ATTR(pwm2, S_IRUGO | S_IWUSR, i8k_hwmon_show_pwm,
+			  i8k_hwmon_set_pwm, 1);
+
+static struct attribute *i8k_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,	/* 0 */
+	&sensor_dev_attr_temp1_label.dev_attr.attr,	/* 1 */
+	&sensor_dev_attr_temp2_input.dev_attr.attr,	/* 2 */
+	&sensor_dev_attr_temp2_label.dev_attr.attr,	/* 3 */
+	&sensor_dev_attr_temp3_input.dev_attr.attr,	/* 4 */
+	&sensor_dev_attr_temp3_label.dev_attr.attr,	/* 5 */
+	&sensor_dev_attr_temp4_input.dev_attr.attr,	/* 6 */
+	&sensor_dev_attr_temp4_label.dev_attr.attr,	/* 7 */
+	&sensor_dev_attr_fan1_input.dev_attr.attr,	/* 8 */
+	&sensor_dev_attr_fan1_label.dev_attr.attr,	/* 9 */
+	&sensor_dev_attr_pwm1.dev_attr.attr,		/* 10 */
+	&sensor_dev_attr_fan2_input.dev_attr.attr,	/* 11 */
+	&sensor_dev_attr_fan2_label.dev_attr.attr,	/* 12 */
+	&sensor_dev_attr_pwm2.dev_attr.attr,		/* 13 */
+	NULL
+};
+
+static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,
+			      int index)
+{
+	if (index >= 0 && index <= 1 &&
+	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))
+		return 0;
+	if (index >= 2 && index <= 3 &&
+	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP2))
+		return 0;
+	if (index >= 4 && index <= 5 &&
+	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP3))
+		return 0;
+	if (index >= 6 && index <= 7 &&
+	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP4))
+		return 0;
+	if (index >= 8 && index <= 10 &&
+	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1))
+		return 0;
+	if (index >= 11 && index <= 13 &&
+	    !(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 type is OK */
+	err = i8k_get_temp_type(0);
+	if (err >= 0)
+		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
+	/* check for additional temperature sensors */
+	err = i8k_get_temp_type(1);
+	if (err >= 0)
+		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
+	err = i8k_get_temp_type(2);
+	if (err >= 0)
+		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
+	err = i8k_get_temp_type(3);
+	if (err >= 0)
+		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;
+
+	/* First fan attributes, if fan type is OK */
+	err = i8k_get_fan_type(0);
+	if (err >= 0)
+		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1;
+
+	/* Second fan attributes, if fan type is OK */
+	err = i8k_get_fan_type(1);
+	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 {
+	uint fan_mult;
+	uint fan_max;
+};
+
+enum i8k_configs {
+	DELL_LATITUDE_D520,
+	DELL_PRECISION_490,
+	DELL_STUDIO,
+	DELL_XPS,
+};
+
+static const struct i8k_config_data i8k_config_data[] = {
+	[DELL_LATITUDE_D520] = {
+		.fan_mult = 1,
+		.fan_max = I8K_FAN_TURBO,
+	},
+	[DELL_PRECISION_490] = {
+		.fan_mult = 1,
+		.fan_max = I8K_FAN_TURBO,
+	},
+	[DELL_STUDIO] = {
+		.fan_mult = 1,
+		.fan_max = I8K_FAN_HIGH,
+	},
+	[DELL_XPS] = {
+		.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 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 13",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "XPS13"),
+		},
+		.driver_data = (void *)&i8k_config_data[DELL_XPS],
+	},
+	{
+		.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],
+	},
+	{ }
+};
+
+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;
+	int fan, ret;
+
+	/*
+	 * 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;
+	}
+
+	/*
+	 * Set fan multiplier and maximal fan speed from dmi config
+	 * Values specified in module parameters override values from dmi
+	 */
+	id = dmi_first_match(i8k_dmi_table);
+	if (id && id->driver_data) {
+		const struct i8k_config_data *conf = id->driver_data;
+		if (!fan_mult && conf->fan_mult)
+			fan_mult = conf->fan_mult;
+		if (!fan_max && conf->fan_max)
+			fan_max = conf->fan_max;
+	}
+
+	i8k_fan_max = fan_max ? : I8K_FAN_HIGH;	/* Must not be 0 */
+	i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);
+
+	if (!fan_mult) {
+		/*
+		 * Autodetect fan multiplier based on nominal rpm
+		 * If fan reports rpm value too high then set multiplier to 1
+		 */
+		for (fan = 0; fan < 2; ++fan) {
+			ret = i8k_get_fan_nominal_speed(fan, i8k_fan_max);
+			if (ret < 0)
+				continue;
+			if (ret > I8K_FAN_MAX_RPM)
+				i8k_fan_mult = 1;
+			break;
+		}
+	} else {
+		/* Fan multiplier was specified in module param or in dmi */
+		i8k_fan_mult = fan_mult;
+	}
+
+	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);