[PATCH] hwmon: New vt8231 driver

Port the vt8231 hardware monitoring driver from lm_sensors CVS to
Linux 2.6.

Signed-off-by: Roger Lucas <roger@planbit.co.uk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 874 insertions, 0 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index db358cfa7cb..c5829591436 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -350,6 +350,18 @@ config SENSORS_VIA686A
 	  This driver can also be built as a module.  If so, the module
 	  will be called via686a.
 
+config SENSORS_VT8231
+	tristate "VT8231"
+	depends on HWMON && I2C && PCI && EXPERIMENTAL
+	select HWMON_VID
+	select I2C_ISA
+	help
+	  If you say yes here then you get support for the integrated sensors
+	  in the VIA VT8231 device.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called vt8231.
+
 config SENSORS_W83781D
 	tristate "Winbond W83781D, W83782D, W83783S, W83627HF, Asus AS99127F"
 	depends on HWMON && I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f7d6a2f61ee..06d4a1d1410 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_SENSORS_SIS5595)	+= sis5595.o
 obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_VIA686A)	+= via686a.o
+obj-$(CONFIG_SENSORS_VT8231)	+= vt8231.o
 obj-$(CONFIG_SENSORS_W83627EHF)	+= w83627ehf.o
 obj-$(CONFIG_SENSORS_W83L785TS)	+= w83l785ts.o
 
diff --git a/drivers/hwmon/vt8231.c b/drivers/hwmon/vt8231.c
new file mode 100644
index 00000000000..c8556a72a1c
--- /dev/null
+++ b/drivers/hwmon/vt8231.c
@@ -0,0 +1,861 @@
+/*
+	vt8231.c - Part of lm_sensors, Linux kernel modules
+				for hardware monitoring
+
+	Copyright (c) 2005 Roger Lucas <roger@planbit.co.uk>
+	Copyright (c) 2002 Mark D. Studebaker <mdsxyz123@yahoo.com>
+			   Aaron M. Marsh <amarsh@sdf.lonestar.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 of the License, 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.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to the Free Software
+	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/* Supports VIA VT8231 South Bridge embedded sensors
+*/
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/i2c-isa.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/hwmon-vid.h>
+#include <linux/err.h>
+#include <asm/io.h>
+
+static int force_addr;
+module_param(force_addr, int, 0);
+MODULE_PARM_DESC(force_addr, "Initialize the base address of the sensors");
+
+/* Device address
+   Note that we can't determine the ISA address until we have initialized
+   our module */
+static unsigned short isa_address;
+
+#define VT8231_EXTENT 0x80
+#define VT8231_BASE_REG 0x70
+#define VT8231_ENABLE_REG 0x74
+
+/* The VT8231 registers
+
+   The reset value for the input channel configuration is used (Reg 0x4A=0x07)
+   which sets the selected inputs marked with '*' below if multiple options are
+   possible:
+
+	            Voltage Mode	  Temperature Mode
+	Sensor	      Linux Id	      Linux Id        VIA Id
+	--------      --------	      --------        ------
+	CPU Diode	N/A		temp1		0
+	UIC1		in0		temp2 *		1
+	UIC2		in1 *		temp3   	2
+	UIC3		in2 *		temp4		3
+	UIC4		in3 *		temp5		4
+	UIC5		in4 *		temp6		5
+	3.3V		in5		N/A
+
+   Note that the BIOS may set the configuration register to a different value
+   to match the motherboard configuration.
+*/
+
+/* fans numbered 0-1 */
+#define VT8231_REG_FAN_MIN(nr)	(0x3b + (nr))
+#define VT8231_REG_FAN(nr)	(0x29 + (nr))
+
+/* Voltage inputs numbered 0-5 */
+
+static const u8 regvolt[]    = { 0x21, 0x22, 0x23, 0x24, 0x25, 0x26 };
+static const u8 regvoltmax[] = { 0x3d, 0x2b, 0x2d, 0x2f, 0x31, 0x33 };
+static const u8 regvoltmin[] = { 0x3e, 0x2c, 0x2e, 0x30, 0x32, 0x34 };
+
+/* Temperatures are numbered 1-6 according to the Linux kernel specification.
+**
+** In the VIA datasheet, however, the temperatures are numbered from zero.
+** Since it is important that this driver can easily be compared to the VIA
+** datasheet, we will use the VIA numbering within this driver and map the
+** kernel sysfs device name to the VIA number in the sysfs callback.
+*/
+
+#define VT8231_REG_TEMP_LOW01	0x49
+#define VT8231_REG_TEMP_LOW25	0x4d
+
+static const u8 regtemp[]    = { 0x1f, 0x21, 0x22, 0x23, 0x24, 0x25 };
+static const u8 regtempmax[] = { 0x39, 0x3d, 0x2b, 0x2d, 0x2f, 0x31 };
+static const u8 regtempmin[] = { 0x3a, 0x3e, 0x2c, 0x2e, 0x30, 0x32 };
+
+#define TEMP_FROM_REG(reg)		(((253 * 4 - (reg)) * 550 + 105) / 210)
+#define TEMP_MAXMIN_FROM_REG(reg)	(((253 - (reg)) * 2200 + 105) / 210)
+#define TEMP_MAXMIN_TO_REG(val)		(253 - ((val) * 210 + 1100) / 2200)
+
+#define VT8231_REG_CONFIG 0x40
+#define VT8231_REG_ALARM1 0x41
+#define VT8231_REG_ALARM2 0x42
+#define VT8231_REG_FANDIV 0x47
+#define VT8231_REG_UCH_CONFIG 0x4a
+#define VT8231_REG_TEMP1_CONFIG 0x4b
+#define VT8231_REG_TEMP2_CONFIG 0x4c
+
+/* temps 0-5 as numbered in VIA datasheet - see later for mapping to Linux
+** numbering
+*/
+#define ISTEMP(i, ch_config) ((i) == 0 ? 1 : \
+			      ((ch_config) >> ((i)+1)) & 0x01)
+/* voltages 0-5 */
+#define ISVOLT(i, ch_config) ((i) == 5 ? 1 : \
+			      !(((ch_config) >> ((i)+2)) & 0x01))
+
+#define DIV_FROM_REG(val) (1 << (val))
+
+/* NB  The values returned here are NOT temperatures.  The calibration curves
+**     for the thermistor curves are board-specific and must go in the
+**     sensors.conf file.  Temperature sensors are actually ten bits, but the
+**     VIA datasheet only considers the 8 MSBs obtained from the regtemp[]
+**     register.  The temperature value returned should have a magnitude of 3,
+**     so we use the VIA scaling as the "true" scaling and use the remaining 2
+**     LSBs as fractional precision.
+**
+**     All the on-chip hardware temperature comparisons for the alarms are only
+**     8-bits wide, and compare against the 8 MSBs of the temperature.  The bits
+**     in the registers VT8231_REG_TEMP_LOW01 and VT8231_REG_TEMP_LOW25 are
+**     ignored.
+*/
+
+/******** FAN RPM CONVERSIONS ********
+** This chip saturates back at 0, not at 255 like many the other chips.
+** So, 0 means 0 RPM
+*/
+static inline u8 FAN_TO_REG(long rpm, int div)
+{
+	if (rpm == 0)
+		return 0;
+	return SENSORS_LIMIT(1310720 / (rpm * div), 1, 255);
+}
+
+#define FAN_FROM_REG(val, div) ((val) == 0 ? 0 : 1310720 / ((val) * (div)))
+
+struct vt8231_data {
+	struct i2c_client client;
+	struct semaphore update_lock;
+	struct class_device *class_dev;
+	char valid;		/* !=0 if following fields are valid */
+	unsigned long last_updated;	/* In jiffies */
+
+	u8 in[6];		/* Register value */
+	u8 in_max[6];		/* Register value */
+	u8 in_min[6];		/* Register value */
+	u16 temp[6];		/* Register value 10 bit, right aligned */
+	u8 temp_max[6];		/* Register value */
+	u8 temp_min[6];		/* Register value */
+	u8 fan[2];		/* Register value */
+	u8 fan_min[2];		/* Register value */
+	u8 fan_div[2];		/* Register encoding, shifted right */
+	u16 alarms;		/* Register encoding */
+	u8 uch_config;
+};
+
+static struct pci_dev *s_bridge;
+static int vt8231_detect(struct i2c_adapter *adapter);
+static int vt8231_detach_client(struct i2c_client *client);
+static struct vt8231_data *vt8231_update_device(struct device *dev);
+static void vt8231_init_client(struct i2c_client *client);
+
+static inline int vt8231_read_value(struct i2c_client *client, u8 reg)
+{
+	return inb_p(client->addr + reg);
+}
+
+static inline void vt8231_write_value(struct i2c_client *client, u8 reg,
+					u8 value)
+{
+	outb_p(value, client->addr + reg);
+}
+
+/* following are the sysfs callback functions */
+static ssize_t show_in(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n", ((data->in[nr] - 3) * 10000) / 958);
+}
+
+static ssize_t show_in_min(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n", ((data->in_min[nr] - 3) * 10000) / 958);
+}
+
+static ssize_t show_in_max(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n", (((data->in_max[nr] - 3) * 10000) / 958));
+}
+
+static ssize_t set_in_min(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->in_min[nr] = SENSORS_LIMIT(((val * 958) / 10000) + 3, 0, 255);
+	vt8231_write_value(client, regvoltmin[nr], data->in_min[nr]);
+	up(&data->update_lock);
+	return count;
+}
+
+static ssize_t set_in_max(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->in_max[nr] = SENSORS_LIMIT(((val * 958) / 10000) + 3, 0, 255);
+	vt8231_write_value(client, regvoltmax[nr], data->in_max[nr]);
+	up(&data->update_lock);
+	return count;
+}
+
+/* Special case for input 5 as this has 3.3V scaling built into the chip */
+static ssize_t show_in5(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n",
+		(((data->in[5] - 3) * 10000 * 54) / (958 * 34)));
+}
+
+static ssize_t show_in5_min(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n",
+		(((data->in_min[5] - 3) * 10000 * 54) / (958 * 34)));
+}
+
+static ssize_t show_in5_max(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+
+	return sprintf(buf, "%d\n",
+		(((data->in_max[5] - 3) * 10000 * 54) / (958 * 34)));
+}
+
+static ssize_t set_in5_min(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->in_min[5] = SENSORS_LIMIT(((val * 958 * 34) / (10000 * 54)) + 3,
+					0, 255);
+	vt8231_write_value(client, regvoltmin[5], data->in_min[5]);
+	up(&data->update_lock);
+	return count;
+}
+
+static ssize_t set_in5_max(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->in_max[5] = SENSORS_LIMIT(((val * 958 * 34) / (10000 * 54)) + 3,
+					0, 255);
+	vt8231_write_value(client, regvoltmax[5], data->in_max[5]);
+	up(&data->update_lock);
+	return count;
+}
+
+#define define_voltage_sysfs(offset)				\
+static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO,		\
+		show_in, NULL, offset);				\
+static SENSOR_DEVICE_ATTR(in##offset##_min, S_IRUGO | S_IWUSR,	\
+		show_in_min, set_in_min, offset);		\
+static SENSOR_DEVICE_ATTR(in##offset##_max, S_IRUGO | S_IWUSR,	\
+		show_in_max, set_in_max, offset)
+
+define_voltage_sysfs(0);
+define_voltage_sysfs(1);
+define_voltage_sysfs(2);
+define_voltage_sysfs(3);
+define_voltage_sysfs(4);
+
+static DEVICE_ATTR(in5_input, S_IRUGO, show_in5, NULL);
+static DEVICE_ATTR(in5_min, S_IRUGO | S_IWUSR, show_in5_min, set_in5_min);
+static DEVICE_ATTR(in5_max, S_IRUGO | S_IWUSR, show_in5_max, set_in5_max);
+
+/* Temperatures */
+static ssize_t show_temp0(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp[0] * 250);
+}
+
+static ssize_t show_temp0_max(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp_max[0] * 1000);
+}
+
+static ssize_t show_temp0_min(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp_min[0] * 1000);
+}
+
+static ssize_t set_temp0_max(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int val = simple_strtol(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->temp_max[0] = SENSORS_LIMIT((val + 500) / 1000, 0, 255);
+	vt8231_write_value(client, regtempmax[0], data->temp_max[0]);
+	up(&data->update_lock);
+	return count;
+}
+static ssize_t set_temp0_min(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int val = simple_strtol(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->temp_min[0] = SENSORS_LIMIT((val + 500) / 1000, 0, 255);
+	vt8231_write_value(client, regtempmin[0], data->temp_min[0]);
+	up(&data->update_lock);
+	return count;
+}
+
+static ssize_t show_temp(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[nr]));
+}
+
+static ssize_t show_temp_max(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", TEMP_MAXMIN_FROM_REG(data->temp_max[nr]));
+}
+
+static ssize_t show_temp_min(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", TEMP_MAXMIN_FROM_REG(data->temp_min[nr]));
+}
+
+static ssize_t set_temp_max(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int val = simple_strtol(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->temp_max[nr] = SENSORS_LIMIT(TEMP_MAXMIN_TO_REG(val), 0, 255);
+	vt8231_write_value(client, regtempmax[nr], data->temp_max[nr]);
+	up(&data->update_lock);
+	return count;
+}
+static ssize_t set_temp_min(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int val = simple_strtol(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->temp_min[nr] = SENSORS_LIMIT(TEMP_MAXMIN_TO_REG(val), 0, 255);
+	vt8231_write_value(client, regtempmin[nr], data->temp_min[nr]);
+	up(&data->update_lock);
+	return count;
+}
+
+/* Note that these map the Linux temperature sensor numbering (1-6) to the VIA
+** temperature sensor numbering (0-5)
+*/
+#define define_temperature_sysfs(offset)				\
+static SENSOR_DEVICE_ATTR(temp##offset##_input, S_IRUGO,		\
+		show_temp, NULL, offset - 1);				\
+static SENSOR_DEVICE_ATTR(temp##offset##_max, S_IRUGO | S_IWUSR,	\
+		show_temp_max, set_temp_max, offset - 1);		\
+static SENSOR_DEVICE_ATTR(temp##offset##_min, S_IRUGO | S_IWUSR,	\
+		show_temp_min, set_temp_min, offset - 1)
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp0, NULL);
+static DEVICE_ATTR(temp1_max, S_IRUGO | S_IWUSR, show_temp0_max, set_temp0_max);
+static DEVICE_ATTR(temp1_min, S_IRUGO | S_IWUSR, show_temp0_min, set_temp0_min);
+
+define_temperature_sysfs(2);
+define_temperature_sysfs(3);
+define_temperature_sysfs(4);
+define_temperature_sysfs(5);
+define_temperature_sysfs(6);
+
+#define CFG_INFO_TEMP(id)	{ &sensor_dev_attr_temp##id##_input.dev_attr, \
+				&sensor_dev_attr_temp##id##_min.dev_attr, \
+				&sensor_dev_attr_temp##id##_max.dev_attr }
+#define CFG_INFO_VOLT(id)	{ &sensor_dev_attr_in##id##_input.dev_attr, \
+				&sensor_dev_attr_in##id##_min.dev_attr, \
+				&sensor_dev_attr_in##id##_max.dev_attr }
+
+struct str_device_attr_table {
+	struct device_attribute *input;
+	struct device_attribute *min;
+	struct device_attribute *max;
+};
+
+static struct str_device_attr_table cfg_info_temp[] = {
+	{ &dev_attr_temp1_input, &dev_attr_temp1_min, &dev_attr_temp1_max },
+	CFG_INFO_TEMP(2),
+	CFG_INFO_TEMP(3),
+	CFG_INFO_TEMP(4),
+	CFG_INFO_TEMP(5),
+	CFG_INFO_TEMP(6)
+};
+
+static struct str_device_attr_table cfg_info_volt[] = {
+	CFG_INFO_VOLT(0),
+	CFG_INFO_VOLT(1),
+	CFG_INFO_VOLT(2),
+	CFG_INFO_VOLT(3),
+	CFG_INFO_VOLT(4),
+	{ &dev_attr_in5_input, &dev_attr_in5_min, &dev_attr_in5_max }
+};
+
+/* Fans */
+static ssize_t show_fan(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[nr],
+				DIV_FROM_REG(data->fan_div[nr])));
+}
+
+static ssize_t show_fan_min(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan_min[nr],
+			DIV_FROM_REG(data->fan_div[nr])));
+}
+
+static ssize_t show_fan_div(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", DIV_FROM_REG(data->fan_div[nr]));
+}
+
+static ssize_t set_fan_min(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int nr = sensor_attr->index;
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int val = simple_strtoul(buf, NULL, 10);
+
+	down(&data->update_lock);
+	data->fan_min[nr] = FAN_TO_REG(val, DIV_FROM_REG(data->fan_div[nr]));
+	vt8231_write_value(client, VT8231_REG_FAN_MIN(nr), data->fan_min[nr]);
+	up(&data->update_lock);
+	return count;
+}
+
+static ssize_t set_fan_div(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+	int nr = sensor_attr->index;
+	int old = vt8231_read_value(client, VT8231_REG_FANDIV);
+	long min = FAN_FROM_REG(data->fan_min[nr],
+				 DIV_FROM_REG(data->fan_div[nr]));
+
+	down(&data->update_lock);
+	switch (val) {
+	case 1: data->fan_div[nr] = 0; break;
+	case 2: data->fan_div[nr] = 1; break;
+	case 4: data->fan_div[nr] = 2; break;
+	case 8: data->fan_div[nr] = 3; break;
+	default:
+		dev_err(&client->dev, "fan_div value %ld not supported."
+		        "Choose one of 1, 2, 4 or 8!\n", val);
+		up(&data->update_lock);
+		return -EINVAL;
+	}
+
+	/* Correct the fan minimum speed */
+	data->fan_min[nr] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[nr]));
+	vt8231_write_value(client, VT8231_REG_FAN_MIN(nr), data->fan_min[nr]);
+
+	old = (old & 0x0f) | (data->fan_div[1] << 6) | (data->fan_div[0] << 4);
+	vt8231_write_value(client, VT8231_REG_FANDIV, old);
+	up(&data->update_lock);
+	return count;
+}
+
+
+#define define_fan_sysfs(offset)					\
+static SENSOR_DEVICE_ATTR(fan##offset##_input, S_IRUGO,			\
+		show_fan, NULL, offset - 1);				\
+static SENSOR_DEVICE_ATTR(fan##offset##_div, S_IRUGO | S_IWUSR,		\
+		show_fan_div, set_fan_div, offset - 1);			\
+static SENSOR_DEVICE_ATTR(fan##offset##_min, S_IRUGO | S_IWUSR,		\
+		show_fan_min, set_fan_min, offset - 1)
+
+define_fan_sysfs(1);
+define_fan_sysfs(2);
+
+/* Alarms */
+static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct vt8231_data *data = vt8231_update_device(dev);
+	return sprintf(buf, "%d\n", data->alarms);
+}
+
+static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
+
+static struct i2c_driver vt8231_driver = {
+	.owner		= THIS_MODULE,
+	.name		= "vt8231",
+	.attach_adapter	= vt8231_detect,
+	.detach_client	= vt8231_detach_client,
+};
+
+static struct pci_device_id vt8231_pci_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8231_4) },
+	{ 0, }
+};
+
+MODULE_DEVICE_TABLE(pci, vt8231_pci_ids);
+
+static int __devinit vt8231_pci_probe(struct pci_dev *dev,
+			 	      const struct pci_device_id *id);
+
+static struct pci_driver vt8231_pci_driver = {
+	.name		= "vt8231",
+	.id_table	= vt8231_pci_ids,
+	.probe		= vt8231_pci_probe,
+};
+
+int vt8231_detect(struct i2c_adapter *adapter)
+{
+	struct i2c_client *client;
+	struct vt8231_data *data;
+	int err = 0, i;
+	u16 val;
+
+	/* 8231 requires multiple of 256 */
+	if (force_addr)	{
+		isa_address = force_addr & 0xFF00;
+		dev_warn(&adapter->dev, "forcing ISA address 0x%04X\n",
+				 isa_address);
+		if (PCIBIOS_SUCCESSFUL != pci_write_config_word(s_bridge,
+						VT8231_BASE_REG, isa_address))
+			return -ENODEV;
+	}
+
+	if (PCIBIOS_SUCCESSFUL !=
+		pci_read_config_word(s_bridge, VT8231_ENABLE_REG, &val))
+		return -ENODEV;
+
+	if (!(val & 0x0001)) {
+		dev_warn(&adapter->dev, "enabling sensors\n");
+		if (PCIBIOS_SUCCESSFUL !=
+			pci_write_config_word(s_bridge, VT8231_ENABLE_REG,
+							  val | 0x0001))
+			return -ENODEV;
+	}
+
+	/* Reserve the ISA region */
+	if (!request_region(isa_address, VT8231_EXTENT,
+			    vt8231_pci_driver.name)) {
+		dev_err(&adapter->dev, "region 0x%x already in use!\n",
+			   isa_address);
+		return -ENODEV;
+	}
+
+	if (!(data = kzalloc(sizeof(struct vt8231_data), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit_release;
+	}
+
+	client = &data->client;
+	i2c_set_clientdata(client, data);
+	client->addr = isa_address;
+	client->adapter = adapter;
+	client->driver = &vt8231_driver;
+	client->dev.parent = &adapter->dev;
+
+	/* Fill in the remaining client fields and put into the global list */
+	strlcpy(client->name, "vt8231", I2C_NAME_SIZE);
+
+	init_MUTEX(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	if ((err = i2c_attach_client(client)))
+		goto exit_free;
+
+	vt8231_init_client(client);
+
+	/* Register sysfs hooks */
+	data->class_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->class_dev)) {
+		err = PTR_ERR(data->class_dev);
+		goto exit_detach;
+	}
+
+	/* Must update device information to find out the config field */
+	data->uch_config = vt8231_read_value(client, VT8231_REG_UCH_CONFIG);
+
+	for (i = 0; i < ARRAY_SIZE(cfg_info_temp); i++) {
+		if (ISTEMP(i, data->uch_config)) {
+			device_create_file(&client->dev,
+					   cfg_info_temp[i].input);
+			device_create_file(&client->dev, cfg_info_temp[i].max);
+			device_create_file(&client->dev, cfg_info_temp[i].min);
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(cfg_info_volt); i++) {
+		if (ISVOLT(i, data->uch_config)) {
+			device_create_file(&client->dev,
+					   cfg_info_volt[i].input);
+			device_create_file(&client->dev, cfg_info_volt[i].max);
+			device_create_file(&client->dev, cfg_info_volt[i].min);
+		}
+	}
+
+	device_create_file(&client->dev, &sensor_dev_attr_fan1_input.dev_attr);
+	device_create_file(&client->dev, &sensor_dev_attr_fan2_input.dev_attr);
+	device_create_file(&client->dev, &sensor_dev_attr_fan1_min.dev_attr);
+	device_create_file(&client->dev, &sensor_dev_attr_fan2_min.dev_attr);
+	device_create_file(&client->dev, &sensor_dev_attr_fan1_div.dev_attr);
+	device_create_file(&client->dev, &sensor_dev_attr_fan2_div.dev_attr);
+
+	device_create_file(&client->dev, &dev_attr_alarms);
+	return 0;
+
+exit_detach:
+	i2c_detach_client(client);
+exit_free:
+	kfree(data);
+exit_release:
+	release_region(isa_address, VT8231_EXTENT);
+	return err;
+}
+
+static int vt8231_detach_client(struct i2c_client *client)
+{
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int err;
+
+	hwmon_device_unregister(data->class_dev);
+
+	if ((err = i2c_detach_client(client))) {
+		return err;
+	}
+
+	release_region(client->addr, VT8231_EXTENT);
+	kfree(data);
+
+	return 0;
+}
+
+static void vt8231_init_client(struct i2c_client *client)
+{
+	vt8231_write_value(client, VT8231_REG_TEMP1_CONFIG, 0);
+	vt8231_write_value(client, VT8231_REG_TEMP2_CONFIG, 0);
+}
+
+static struct vt8231_data *vt8231_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct vt8231_data *data = i2c_get_clientdata(client);
+	int i;
+	u16 low;
+
+	down(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
+	    || !data->valid) {
+		for (i = 0; i < 6; i++) {
+			if (ISVOLT(i, data->uch_config)) {
+				data->in[i] = vt8231_read_value(client,
+						regvolt[i]);
+				data->in_min[i] = vt8231_read_value(client,
+						regvoltmin[i]);
+				data->in_max[i] = vt8231_read_value(client,
+						regvoltmax[i]);
+			}
+		}
+		for (i = 0; i < 2; i++) {
+			data->fan[i] = vt8231_read_value(client,
+						VT8231_REG_FAN(i));
+			data->fan_min[i] = vt8231_read_value(client,
+						VT8231_REG_FAN_MIN(i));
+		}
+
+		low = vt8231_read_value(client, VT8231_REG_TEMP_LOW01);
+		low = (low >> 6) | ((low & 0x30) >> 2)
+		    | (vt8231_read_value(client, VT8231_REG_TEMP_LOW25) << 4);
+		for (i = 0; i < 6; i++) {
+			if (ISTEMP(i, data->uch_config)) {
+				data->temp[i] = (vt8231_read_value(client,
+						       regtemp[i]) << 2)
+						| ((low >> (2 * i)) & 0x03);
+				data->temp_max[i] = vt8231_read_value(client,
+						      regtempmax[i]);
+				data->temp_min[i] = vt8231_read_value(client,
+						      regtempmin[i]);
+			}
+		}
+
+		i = vt8231_read_value(client, VT8231_REG_FANDIV);
+		data->fan_div[0] = (i >> 4) & 0x03;
+		data->fan_div[1] = i >> 6;
+		data->alarms = vt8231_read_value(client, VT8231_REG_ALARM1) |
+			(vt8231_read_value(client, VT8231_REG_ALARM2) << 8);
+
+		/* Set alarm flags correctly */
+		if (!data->fan[0] && data->fan_min[0]) {
+			data->alarms |= 0x40;
+		} else if (data->fan[0] && !data->fan_min[0]) {
+			data->alarms &= ~0x40;
+		}
+
+		if (!data->fan[1] && data->fan_min[1]) {
+			data->alarms |= 0x80;
+		} else if (data->fan[1] && !data->fan_min[1]) {
+			data->alarms &= ~0x80;
+		}
+
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+
+	up(&data->update_lock);
+
+	return data;
+}
+
+static int __devinit vt8231_pci_probe(struct pci_dev *dev,
+				const struct pci_device_id *id)
+{
+	u16 val;
+
+	if (PCIBIOS_SUCCESSFUL != pci_read_config_word(dev, VT8231_BASE_REG,
+							&val))
+		return -ENODEV;
+
+	isa_address = val & ~(VT8231_EXTENT - 1);
+	if (isa_address == 0 && force_addr == 0) {
+		dev_err(&dev->dev, "base address not set -\
+				 upgrade BIOS or use force_addr=0xaddr\n");
+		return -ENODEV;
+	}
+
+	s_bridge = pci_dev_get(dev);
+
+	if (i2c_isa_add_driver(&vt8231_driver)) {
+		pci_dev_put(s_bridge);
+		s_bridge = NULL;
+	}
+
+	/* Always return failure here.  This is to allow other drivers to bind
+	 * to this pci device.  We don't really want to have control over the
+	 * pci device, we only wanted to read as few register values from it.
+	 */
+	return -ENODEV;
+}
+
+static int __init sm_vt8231_init(void)
+{
+	return pci_module_init(&vt8231_pci_driver);
+}
+
+static void __exit sm_vt8231_exit(void)
+{
+	pci_unregister_driver(&vt8231_pci_driver);
+	if (s_bridge != NULL) {
+		i2c_isa_del_driver(&vt8231_driver);
+		pci_dev_put(s_bridge);
+		s_bridge = NULL;
+	}
+}
+
+MODULE_AUTHOR("Roger Lucas <roger@planbit.co.uk>");
+MODULE_DESCRIPTION("VT8231 sensors");
+MODULE_LICENSE("GPL");
+
+module_init(sm_vt8231_init);
+module_exit(sm_vt8231_exit);