hwmon: New PC87427 hardware monitoring driver

This is a new hardware monitoring driver for the National Semiconductor
PC87427 Super-I/O chip. It only supports fan speed monitoring for now,
while the chip can do much more.

Thanks to Amir Habibi at Candelis for setting up a test system, and to
Michael Kress for testing several iterations of this driver.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

3 files changed, 641 insertions, 0 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 39ab2fc128cf..e379ac41c09c 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -353,6 +353,19 @@ config SENSORS_PC87360
 	  This driver can also be built as a module.  If so, the module
 	  will be called pc87360.
 
+config SENSORS_PC87427
+	tristate "National Semiconductor PC87427"
+	depends on HWMON && EXPERIMENTAL
+	help
+	  If you say yes here you get access to the hardware monitoring
+	  functions of the National Semiconductor PC87427 Super-I/O chip.
+	  The chip has two distinct logical devices, one for fan speed
+	  monitoring and control, and one for voltage and temperature
+	  monitoring. Only fan speed monitoring is supported right now.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called pc87427.
+
 config SENSORS_SIS5595
 	tristate "Silicon Integrated Systems Corp. SiS5595"
 	depends on HWMON && I2C && PCI && EXPERIMENTAL
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index af01cc64f7d2..95f3fc561186 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_SENSORS_LM90)	+= lm90.o
 obj-$(CONFIG_SENSORS_LM92)	+= lm92.o
 obj-$(CONFIG_SENSORS_MAX1619)	+= max1619.o
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
+obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_SIS5595)	+= sis5595.o
 obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
diff --git a/drivers/hwmon/pc87427.c b/drivers/hwmon/pc87427.c
new file mode 100644
index 000000000000..affa21a5ccfd
--- /dev/null
+++ b/drivers/hwmon/pc87427.c
@@ -0,0 +1,627 @@
+/*
+ *  pc87427.c - hardware monitoring driver for the
+ *              National Semiconductor PC87427 Super-I/O chip
+ *  Copyright (C) 2006 Jean Delvare <khali@linux-fr.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ *  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.
+ *
+ *  Supports the following chips:
+ *
+ *  Chip        #vin    #fan    #pwm    #temp   devid
+ *  PC87427     -       8       -       -       0xF2
+ *
+ *  This driver assumes that no more than one chip is present.
+ *  Only fan inputs are supported so far, although the chip can do much more.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/platform_device.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <asm/io.h>
+
+static struct platform_device *pdev;
+
+#define DRVNAME "pc87427"
+
+/* The lock mutex protects both the I/O accesses (needed because the
+   device is using banked registers) and the register cache (needed to keep
+   the data in the registers and the cache in sync at any time). */
+struct pc87427_data {
+	struct class_device *class_dev;
+	struct mutex lock;
+	int address[2];
+	const char *name;
+
+	unsigned long last_updated;	/* in jiffies */
+	u8 fan_enabled;			/* bit vector */
+	u16 fan[8];			/* register values */
+	u16 fan_min[8];			/* register values */
+	u8 fan_status[8];		/* register values */
+};
+
+/*
+ * Super-I/O registers and operations
+ */
+
+#define SIOREG_LDSEL	0x07	/* Logical device select */
+#define SIOREG_DEVID	0x20	/* Device ID */
+#define SIOREG_ACT	0x30	/* Device activation */
+#define SIOREG_MAP	0x50	/* I/O or memory mapping */
+#define SIOREG_IOBASE	0x60	/* I/O base address */
+
+static const u8 logdev[2] = { 0x09, 0x14 };
+static const char *logdev_str[2] = { DRVNAME " FMC", DRVNAME " HMC" };
+#define LD_FAN		0
+#define LD_IN		1
+#define LD_TEMP		1
+
+static inline void superio_outb(int sioaddr, int reg, int val)
+{
+	outb(reg, sioaddr);
+	outb(val, sioaddr + 1);
+}
+
+static inline int superio_inb(int sioaddr, int reg)
+{
+	outb(reg, sioaddr);
+	return inb(sioaddr + 1);
+}
+
+static inline void superio_exit(int sioaddr)
+{
+	outb(0x02, sioaddr);
+	outb(0x02, sioaddr + 1);
+}
+
+/*
+ * Logical devices
+ */
+
+#define REGION_LENGTH		32
+#define PC87427_REG_BANK	0x0f
+#define BANK_FM(nr)		(nr)
+#define BANK_FT(nr)		(0x08 + (nr))
+#define BANK_FC(nr)		(0x10 + (nr) * 2)
+
+/*
+ * I/O access functions
+ */
+
+/* ldi is the logical device index */
+static inline int pc87427_read8(struct pc87427_data *data, u8 ldi, u8 reg)
+{
+	return inb(data->address[ldi] + reg);
+}
+
+/* Must be called with data->lock held, except during init */
+static inline int pc87427_read8_bank(struct pc87427_data *data, u8 ldi,
+				     u8 bank, u8 reg)
+{
+	outb(bank, data->address[ldi] + PC87427_REG_BANK);
+	return inb(data->address[ldi] + reg);
+}
+
+/* Must be called with data->lock held, except during init */
+static inline void pc87427_write8_bank(struct pc87427_data *data, u8 ldi,
+				       u8 bank, u8 reg, u8 value)
+{
+	outb(bank, data->address[ldi] + PC87427_REG_BANK);
+	outb(value, data->address[ldi] + reg);
+}
+
+/*
+ * Fan registers and conversions
+ */
+
+/* fan data registers are 16-bit wide */
+#define PC87427_REG_FAN			0x12
+#define PC87427_REG_FAN_MIN		0x14
+#define PC87427_REG_FAN_STATUS		0x10
+
+#define FAN_STATUS_STALL		(1 << 3)
+#define FAN_STATUS_LOSPD		(1 << 1)
+#define FAN_STATUS_MONEN		(1 << 0)
+
+/* Dedicated function to read all registers related to a given fan input.
+   This saves us quite a few locks and bank selections.
+   Must be called with data->lock held.
+   nr is from 0 to 7 */
+static void pc87427_readall_fan(struct pc87427_data *data, u8 nr)
+{
+	int iobase = data->address[LD_FAN];
+
+	outb(BANK_FM(nr), iobase + PC87427_REG_BANK);
+	data->fan[nr] = inw(iobase + PC87427_REG_FAN);
+	data->fan_min[nr] = inw(iobase + PC87427_REG_FAN_MIN);
+	data->fan_status[nr] = inb(iobase + PC87427_REG_FAN_STATUS);
+	/* Clear fan alarm bits */
+	outb(data->fan_status[nr], iobase + PC87427_REG_FAN_STATUS);
+}
+
+/* The 2 LSB of fan speed registers are used for something different.
+   The actual 2 LSB of the measurements are not available. */
+static inline unsigned long fan_from_reg(u16 reg)
+{
+	reg &= 0xfffc;
+	if (reg == 0x0000 || reg == 0xfffc)
+		return 0;
+	return 5400000UL / reg;
+}
+
+/* The 2 LSB of the fan speed limit registers are not significant. */
+static inline u16 fan_to_reg(unsigned long val)
+{
+	if (val < 83UL)
+		return 0xffff;
+	if (val >= 1350000UL)
+		return 0x0004;
+	return ((1350000UL + val / 2) / val) << 2;
+}
+
+/*
+ * Data interface
+ */
+
+static struct pc87427_data *pc87427_update_device(struct device *dev)
+{
+	struct pc87427_data *data = dev_get_drvdata(dev);
+	int i;
+
+	mutex_lock(&data->lock);
+	if (!time_after(jiffies, data->last_updated + HZ)
+	 && data->last_updated)
+		goto done;
+
+	/* Fans */
+	for (i = 0; i < 8; i++) {
+		if (!(data->fan_enabled & (1 << i)))
+			continue;
+		pc87427_readall_fan(data, i);
+	}
+	data->last_updated = jiffies;
+
+done:
+	mutex_unlock(&data->lock);
+	return data;
+}
+
+static ssize_t show_fan_input(struct device *dev, struct device_attribute
+			      *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct pc87427_data *data = pc87427_update_device(dev);
+	int nr = attr->index;
+
+	return sprintf(buf, "%lu\n", fan_from_reg(data->fan[nr]));
+}
+
+static ssize_t show_fan_min(struct device *dev, struct device_attribute
+			    *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct pc87427_data *data = pc87427_update_device(dev);
+	int nr = attr->index;
+
+	return sprintf(buf, "%lu\n", fan_from_reg(data->fan_min[nr]));
+}
+
+static ssize_t show_fan_alarm(struct device *dev, struct device_attribute
+			      *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct pc87427_data *data = pc87427_update_device(dev);
+	int nr = attr->index;
+
+	return sprintf(buf, "%d\n", !!(data->fan_status[nr]
+				       & FAN_STATUS_LOSPD));
+}
+
+static ssize_t show_fan_fault(struct device *dev, struct device_attribute
+			      *devattr, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	struct pc87427_data *data = pc87427_update_device(dev);
+	int nr = attr->index;
+
+	return sprintf(buf, "%d\n", !!(data->fan_status[nr]
+				       & FAN_STATUS_STALL));
+}
+
+static ssize_t set_fan_min(struct device *dev, struct device_attribute
+			   *devattr, const char *buf, size_t count)
+{
+	struct pc87427_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	int nr = attr->index;
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+	int iobase = data->address[LD_FAN];
+
+	mutex_lock(&data->lock);
+	outb(BANK_FM(nr), iobase + PC87427_REG_BANK);
+	/* The low speed limit registers are read-only while monitoring
+	   is enabled, so we have to disable monitoring, then change the
+	   limit, and finally enable monitoring again. */
+	outb(0, iobase + PC87427_REG_FAN_STATUS);
+	data->fan_min[nr] = fan_to_reg(val);
+	outw(data->fan_min[nr], iobase + PC87427_REG_FAN_MIN);
+	outb(FAN_STATUS_MONEN, iobase + PC87427_REG_FAN_STATUS);
+	mutex_unlock(&data->lock);
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, show_fan_input, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, show_fan_input, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, show_fan_input, NULL, 2);
+static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, show_fan_input, NULL, 3);
+static SENSOR_DEVICE_ATTR(fan5_input, S_IRUGO, show_fan_input, NULL, 4);
+static SENSOR_DEVICE_ATTR(fan6_input, S_IRUGO, show_fan_input, NULL, 5);
+static SENSOR_DEVICE_ATTR(fan7_input, S_IRUGO, show_fan_input, NULL, 6);
+static SENSOR_DEVICE_ATTR(fan8_input, S_IRUGO, show_fan_input, NULL, 7);
+
+static SENSOR_DEVICE_ATTR(fan1_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 0);
+static SENSOR_DEVICE_ATTR(fan2_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 1);
+static SENSOR_DEVICE_ATTR(fan3_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 2);
+static SENSOR_DEVICE_ATTR(fan4_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 3);
+static SENSOR_DEVICE_ATTR(fan5_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 4);
+static SENSOR_DEVICE_ATTR(fan6_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 5);
+static SENSOR_DEVICE_ATTR(fan7_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 6);
+static SENSOR_DEVICE_ATTR(fan8_min, S_IWUSR | S_IRUGO,
+			  show_fan_min, set_fan_min, 7);
+
+static SENSOR_DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_alarm, S_IRUGO, show_fan_alarm, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan3_alarm, S_IRUGO, show_fan_alarm, NULL, 2);
+static SENSOR_DEVICE_ATTR(fan4_alarm, S_IRUGO, show_fan_alarm, NULL, 3);
+static SENSOR_DEVICE_ATTR(fan5_alarm, S_IRUGO, show_fan_alarm, NULL, 4);
+static SENSOR_DEVICE_ATTR(fan6_alarm, S_IRUGO, show_fan_alarm, NULL, 5);
+static SENSOR_DEVICE_ATTR(fan7_alarm, S_IRUGO, show_fan_alarm, NULL, 6);
+static SENSOR_DEVICE_ATTR(fan8_alarm, S_IRUGO, show_fan_alarm, NULL, 7);
+
+static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, show_fan_fault, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_fault, S_IRUGO, show_fan_fault, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan3_fault, S_IRUGO, show_fan_fault, NULL, 2);
+static SENSOR_DEVICE_ATTR(fan4_fault, S_IRUGO, show_fan_fault, NULL, 3);
+static SENSOR_DEVICE_ATTR(fan5_fault, S_IRUGO, show_fan_fault, NULL, 4);
+static SENSOR_DEVICE_ATTR(fan6_fault, S_IRUGO, show_fan_fault, NULL, 5);
+static SENSOR_DEVICE_ATTR(fan7_fault, S_IRUGO, show_fan_fault, NULL, 6);
+static SENSOR_DEVICE_ATTR(fan8_fault, S_IRUGO, show_fan_fault, NULL, 7);
+
+static struct attribute *pc87427_attributes_fan[8][5] = {
+	{
+		&sensor_dev_attr_fan1_input.dev_attr.attr,
+		&sensor_dev_attr_fan1_min.dev_attr.attr,
+		&sensor_dev_attr_fan1_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan1_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan2_input.dev_attr.attr,
+		&sensor_dev_attr_fan2_min.dev_attr.attr,
+		&sensor_dev_attr_fan2_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan2_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan3_input.dev_attr.attr,
+		&sensor_dev_attr_fan3_min.dev_attr.attr,
+		&sensor_dev_attr_fan3_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan3_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan4_input.dev_attr.attr,
+		&sensor_dev_attr_fan4_min.dev_attr.attr,
+		&sensor_dev_attr_fan4_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan4_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan5_input.dev_attr.attr,
+		&sensor_dev_attr_fan5_min.dev_attr.attr,
+		&sensor_dev_attr_fan5_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan5_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan6_input.dev_attr.attr,
+		&sensor_dev_attr_fan6_min.dev_attr.attr,
+		&sensor_dev_attr_fan6_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan6_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan7_input.dev_attr.attr,
+		&sensor_dev_attr_fan7_min.dev_attr.attr,
+		&sensor_dev_attr_fan7_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan7_fault.dev_attr.attr,
+		NULL
+	}, {
+		&sensor_dev_attr_fan8_input.dev_attr.attr,
+		&sensor_dev_attr_fan8_min.dev_attr.attr,
+		&sensor_dev_attr_fan8_alarm.dev_attr.attr,
+		&sensor_dev_attr_fan8_fault.dev_attr.attr,
+		NULL
+	}
+};
+
+static const struct attribute_group pc87427_group_fan[8] = {
+	{ .attrs = pc87427_attributes_fan[0] },
+	{ .attrs = pc87427_attributes_fan[1] },
+	{ .attrs = pc87427_attributes_fan[2] },
+	{ .attrs = pc87427_attributes_fan[3] },
+	{ .attrs = pc87427_attributes_fan[4] },
+	{ .attrs = pc87427_attributes_fan[5] },
+	{ .attrs = pc87427_attributes_fan[6] },
+	{ .attrs = pc87427_attributes_fan[7] },
+};
+
+static ssize_t show_name(struct device *dev, struct device_attribute
+			 *devattr, char *buf)
+{
+	struct pc87427_data *data = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", data->name);
+}
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+
+
+/*
+ * Device detection, attach and detach
+ */
+
+static void __devinit pc87427_init_device(struct device *dev)
+{
+	struct pc87427_data *data = dev_get_drvdata(dev);
+	int i;
+	u8 reg;
+
+	/* The FMC module should be ready */
+	reg = pc87427_read8(data, LD_FAN, PC87427_REG_BANK);
+	if (!(reg & 0x80))
+		dev_warn(dev, "FMC module not ready!\n");
+
+	/* Check which fans are enabled */
+	for (i = 0; i < 8; i++) {
+		reg = pc87427_read8_bank(data, LD_FAN, BANK_FM(i),
+					 PC87427_REG_FAN_STATUS);
+		if (reg & FAN_STATUS_MONEN)
+			data->fan_enabled |= (1 << i);
+	}
+
+	if (!data->fan_enabled) {
+		dev_dbg(dev, "Enabling all fan inputs\n");
+		for (i = 0; i < 8; i++)
+			pc87427_write8_bank(data, LD_FAN, BANK_FM(i),
+					    PC87427_REG_FAN_STATUS,
+					    FAN_STATUS_MONEN);
+		data->fan_enabled = 0xff;
+	}
+}
+
+static int __devinit pc87427_probe(struct platform_device *pdev)
+{
+	struct pc87427_data *data;
+	struct resource *res;
+	int i, err;
+
+	if (!(data = kzalloc(sizeof(struct pc87427_data), GFP_KERNEL))) {
+		err = -ENOMEM;
+		printk(KERN_ERR DRVNAME ": Out of memory\n");
+		goto exit;
+	}
+
+	/* This will need to be revisited when we add support for
+	   temperature and voltage monitoring. */
+	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+	data->address[0] = res->start;
+
+	mutex_init(&data->lock);
+	data->name = "pc87427";
+	platform_set_drvdata(pdev, data);
+	pc87427_init_device(&pdev->dev);
+
+	/* Register sysfs hooks */
+	if ((err = device_create_file(&pdev->dev, &dev_attr_name)))
+		goto exit_kfree;
+	for (i = 0; i < 8; i++) {
+		if (!(data->fan_enabled & (1 << i)))
+			continue;
+		if ((err = sysfs_create_group(&pdev->dev.kobj,
+					      &pc87427_group_fan[i])))
+			goto exit_remove_files;
+	}
+
+	data->class_dev = hwmon_device_register(&pdev->dev);
+	if (IS_ERR(data->class_dev)) {
+		err = PTR_ERR(data->class_dev);
+		dev_err(&pdev->dev, "Class registration failed (%d)\n", err);
+		goto exit_remove_files;
+	}
+
+	return 0;
+
+exit_remove_files:
+	for (i = 0; i < 8; i++) {
+		if (!(data->fan_enabled & (1 << i)))
+			continue;
+		sysfs_remove_group(&pdev->dev.kobj, &pc87427_group_fan[i]);
+	}
+exit_kfree:
+	platform_set_drvdata(pdev, NULL);
+	kfree(data);
+exit:
+	return err;
+}
+
+static int __devexit pc87427_remove(struct platform_device *pdev)
+{
+	struct pc87427_data *data = platform_get_drvdata(pdev);
+	int i;
+
+	platform_set_drvdata(pdev, NULL);
+	hwmon_device_unregister(data->class_dev);
+	device_remove_file(&pdev->dev, &dev_attr_name);
+	for (i = 0; i < 8; i++) {
+		if (!(data->fan_enabled & (1 << i)))
+			continue;
+		sysfs_remove_group(&pdev->dev.kobj, &pc87427_group_fan[i]);
+	}
+	kfree(data);
+
+	return 0;
+}
+
+
+static struct platform_driver pc87427_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= DRVNAME,
+	},
+	.probe		= pc87427_probe,
+	.remove		= __devexit_p(pc87427_remove),
+};
+
+static int __init pc87427_device_add(unsigned short address)
+{
+	struct resource res = {
+		.start	= address,
+		.end	= address + REGION_LENGTH - 1,
+		.name	= logdev_str[0],
+		.flags	= IORESOURCE_IO,
+	};
+	int err;
+
+	pdev = platform_device_alloc(DRVNAME, address);
+	if (!pdev) {
+		err = -ENOMEM;
+		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
+		goto exit;
+	}
+
+	err = platform_device_add_resources(pdev, &res, 1);
+	if (err) {
+		printk(KERN_ERR DRVNAME ": Device resource addition failed "
+		       "(%d)\n", err);
+		goto exit_device_put;
+	}
+
+	err = platform_device_add(pdev);
+	if (err) {
+		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
+		       err);
+		goto exit_device_put;
+	}
+
+	return 0;
+
+exit_device_put:
+	platform_device_put(pdev);
+exit:
+	return err;
+}
+
+static int __init pc87427_find(int sioaddr, unsigned short *address)
+{
+	u16 val;
+	int i, err = 0;
+
+	/* Identify device */
+	val = superio_inb(sioaddr, SIOREG_DEVID);
+	if (val != 0xf2) {	/* PC87427 */
+		err = -ENODEV;
+		goto exit;
+	}
+
+	for (i = 0; i < 2; i++) {
+		address[i] = 0;
+		/* Select logical device */
+		superio_outb(sioaddr, SIOREG_LDSEL, logdev[i]);
+
+		val = superio_inb(sioaddr, SIOREG_ACT);
+		if (!(val & 0x01)) {
+			printk(KERN_INFO DRVNAME ": Logical device 0x%02x "
+			       "not activated\n", logdev[i]);
+			continue;
+		}
+
+		val = superio_inb(sioaddr, SIOREG_MAP);
+		if (val & 0x01) {
+			printk(KERN_WARNING DRVNAME ": Logical device 0x%02x "
+			       "is memory-mapped, can't use\n", logdev[i]);
+			continue;
+		}
+
+		val = (superio_inb(sioaddr, SIOREG_IOBASE) << 8)
+		    | superio_inb(sioaddr, SIOREG_IOBASE + 1);
+		if (!val) {
+			printk(KERN_INFO DRVNAME ": I/O base address not set "
+			       "for logical device 0x%02x\n", logdev[i]);
+			continue;
+		}
+		address[i] = val;
+	}
+
+exit:
+	superio_exit(sioaddr);
+	return err;
+}
+
+static int __init pc87427_init(void)
+{
+	int err;
+	unsigned short address[2];
+
+	if (pc87427_find(0x2e, address)
+	 && pc87427_find(0x4e, address))
+		return -ENODEV;
+
+	/* For now the driver only handles fans so we only care about the
+	   first address. */
+	if (!address[0])
+		return -ENODEV;
+
+	err = platform_driver_register(&pc87427_driver);
+	if (err)
+		goto exit;
+
+	/* Sets global pdev as a side effect */
+	err = pc87427_device_add(address[0]);
+	if (err)
+		goto exit_driver;
+
+	return 0;
+
+exit_driver:
+	platform_driver_unregister(&pc87427_driver);
+exit:
+	return err;
+}
+
+static void __exit pc87427_exit(void)
+{
+	platform_device_unregister(pdev);
+	platform_driver_unregister(&pc87427_driver);
+}
+
+MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
+MODULE_DESCRIPTION("PC87427 hardware monitoring driver");
+MODULE_LICENSE("GPL");
+
+module_init(pc87427_init);
+module_exit(pc87427_exit);