Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 626 insertions, 0 deletions

diff --git a/drivers/i2c/chips/lm90.c b/drivers/i2c/chips/lm90.c
new file mode 100644
index 000000000000..2c00ff83babc
--- /dev/null
+++ b/drivers/i2c/chips/lm90.c
@@ -0,0 +1,626 @@
+/*
+ * lm90.c - Part of lm_sensors, Linux kernel modules for hardware
+ *          monitoring
+ * Copyright (C) 2003-2004  Jean Delvare <khali@linux-fr.org>
+ *
+ * Based on the lm83 driver. The LM90 is a sensor chip made by National
+ * Semiconductor. It reports up to two temperatures (its own plus up to
+ * one external one) with a 0.125 deg resolution (1 deg for local
+ * temperature) and a 3-4 deg accuracy. Complete datasheet can be
+ * obtained from National's website at:
+ *   http://www.national.com/pf/LM/LM90.html
+ *
+ * This driver also supports the LM89 and LM99, two other sensor chips
+ * made by National Semiconductor. Both have an increased remote
+ * temperature measurement accuracy (1 degree), and the LM99
+ * additionally shifts remote temperatures (measured and limits) by 16
+ * degrees, which allows for higher temperatures measurement. The
+ * driver doesn't handle it since it can be done easily in user-space.
+ * Complete datasheets can be obtained from National's website at:
+ *   http://www.national.com/pf/LM/LM89.html
+ *   http://www.national.com/pf/LM/LM99.html
+ * Note that there is no way to differenciate between both chips.
+ *
+ * This driver also supports the LM86, another sensor chip made by
+ * National Semiconductor. It is exactly similar to the LM90 except it
+ * has a higher accuracy.
+ * Complete datasheet can be obtained from National's website at:
+ *   http://www.national.com/pf/LM/LM86.html
+ *
+ * This driver also supports the ADM1032, a sensor chip made by Analog
+ * Devices. That chip is similar to the LM90, with a few differences
+ * that are not handled by this driver. Complete datasheet can be
+ * obtained from Analog's website at:
+ *   http://products.analog.com/products/info.asp?product=ADM1032
+ * Among others, it has a higher accuracy than the LM90, much like the
+ * LM86 does.
+ *
+ * This driver also supports the MAX6657, MAX6658 and MAX6659 sensor
+ * chips made by Maxim. These chips are similar to the LM86. Complete
+ * datasheet can be obtained at Maxim's website at:
+ *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
+ * Note that there is no easy way to differenciate between the three
+ * variants. The extra address and features of the MAX6659 are not
+ * supported by this driver.
+ *
+ * This driver also supports the ADT7461 chip from Analog Devices but
+ * only in its "compatability mode". If an ADT7461 chip is found but
+ * is configured in non-compatible mode (where its temperature
+ * register values are decoded differently) it is ignored by this
+ * driver. Complete datasheet can be obtained from Analog's website
+ * at:
+ *   http://products.analog.com/products/info.asp?product=ADT7461
+ *
+ * Since the LM90 was the first chipset supported by this driver, most
+ * comments will refer to this chipset, but are actually general and
+ * concern all supported chipsets, unless mentioned otherwise.
+ *
+ * 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.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+
+/*
+ * Addresses to scan
+ * Address is fully defined internally and cannot be changed except for
+ * MAX6659.
+ * LM86, LM89, LM90, LM99, ADM1032, MAX6657 and MAX6658 have address 0x4c.
+ * LM89-1, and LM99-1 have address 0x4d.
+ * MAX6659 can have address 0x4c, 0x4d or 0x4e (unsupported).
+ * ADT7461 always has address 0x4c.
+ */
+
+static unsigned short normal_i2c[] = { 0x4c, 0x4d, I2C_CLIENT_END };
+static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
+
+/*
+ * Insmod parameters
+ */
+
+SENSORS_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461);
+
+/*
+ * The LM90 registers
+ */
+
+#define LM90_REG_R_MAN_ID               0xFE
+#define LM90_REG_R_CHIP_ID              0xFF
+#define LM90_REG_R_CONFIG1              0x03
+#define LM90_REG_W_CONFIG1              0x09
+#define LM90_REG_R_CONFIG2              0xBF
+#define LM90_REG_W_CONFIG2              0xBF
+#define LM90_REG_R_CONVRATE             0x04
+#define LM90_REG_W_CONVRATE             0x0A
+#define LM90_REG_R_STATUS               0x02
+#define LM90_REG_R_LOCAL_TEMP           0x00
+#define LM90_REG_R_LOCAL_HIGH           0x05
+#define LM90_REG_W_LOCAL_HIGH           0x0B
+#define LM90_REG_R_LOCAL_LOW            0x06
+#define LM90_REG_W_LOCAL_LOW            0x0C
+#define LM90_REG_R_LOCAL_CRIT           0x20
+#define LM90_REG_W_LOCAL_CRIT           0x20
+#define LM90_REG_R_REMOTE_TEMPH         0x01
+#define LM90_REG_R_REMOTE_TEMPL         0x10
+#define LM90_REG_R_REMOTE_OFFSH         0x11
+#define LM90_REG_W_REMOTE_OFFSH         0x11
+#define LM90_REG_R_REMOTE_OFFSL         0x12
+#define LM90_REG_W_REMOTE_OFFSL         0x12
+#define LM90_REG_R_REMOTE_HIGHH         0x07
+#define LM90_REG_W_REMOTE_HIGHH         0x0D
+#define LM90_REG_R_REMOTE_HIGHL         0x13
+#define LM90_REG_W_REMOTE_HIGHL         0x13
+#define LM90_REG_R_REMOTE_LOWH          0x08
+#define LM90_REG_W_REMOTE_LOWH          0x0E
+#define LM90_REG_R_REMOTE_LOWL          0x14
+#define LM90_REG_W_REMOTE_LOWL          0x14
+#define LM90_REG_R_REMOTE_CRIT          0x19
+#define LM90_REG_W_REMOTE_CRIT          0x19
+#define LM90_REG_R_TCRIT_HYST           0x21
+#define LM90_REG_W_TCRIT_HYST           0x21
+
+/*
+ * Conversions and various macros
+ * For local temperatures and limits, critical limits and the hysteresis
+ * value, the LM90 uses signed 8-bit values with LSB = 1 degree Celcius.
+ * For remote temperatures and limits, it uses signed 11-bit values with
+ * LSB = 0.125 degree Celcius, left-justified in 16-bit registers.
+ */
+
+#define TEMP1_FROM_REG(val)     ((val) * 1000)
+#define TEMP1_TO_REG(val)       ((val) <= -128000 ? -128 : \
+                                 (val) >= 127000 ? 127 : \
+                                 (val) < 0 ? ((val) - 500) / 1000 : \
+                                 ((val) + 500) / 1000)
+#define TEMP2_FROM_REG(val)     ((val) / 32 * 125)
+#define TEMP2_TO_REG(val)       ((val) <= -128000 ? 0x8000 : \
+                                 (val) >= 127875 ? 0x7FE0 : \
+                                 (val) < 0 ? ((val) - 62) / 125 * 32 : \
+                                 ((val) + 62) / 125 * 32)
+#define HYST_TO_REG(val)        ((val) <= 0 ? 0 : (val) >= 30500 ? 31 : \
+                                 ((val) + 500) / 1000)
+
+/* 
+ * ADT7461 is almost identical to LM90 except that attempts to write
+ * values that are outside the range 0 < temp < 127 are treated as
+ * the boundary value. 
+ */
+
+#define TEMP1_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \
+                                 (val) >= 127000 ? 127 : \
+                                 ((val) + 500) / 1000)
+#define TEMP2_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \
+                                 (val) >= 127750 ? 0x7FC0 : \
+                                 ((val) + 125) / 250 * 64)
+
+/*
+ * Functions declaration
+ */
+
+static int lm90_attach_adapter(struct i2c_adapter *adapter);
+static int lm90_detect(struct i2c_adapter *adapter, int address,
+        int kind);
+static void lm90_init_client(struct i2c_client *client);
+static int lm90_detach_client(struct i2c_client *client);
+static struct lm90_data *lm90_update_device(struct device *dev);
+
+/*
+ * Driver data (common to all clients)
+ */
+
+static struct i2c_driver lm90_driver = {
+        .owner          = THIS_MODULE,
+        .name           = "lm90",
+        .id             = I2C_DRIVERID_LM90,
+        .flags          = I2C_DF_NOTIFY,
+        .attach_adapter = lm90_attach_adapter,
+        .detach_client  = lm90_detach_client,
+};
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct lm90_data {
+        struct i2c_client client;
+        struct semaphore update_lock;
+        char valid; /* zero until following fields are valid */
+        unsigned long last_updated; /* in jiffies */
+        int kind;
+
+        /* registers values */
+        s8 temp_input1, temp_low1, temp_high1; /* local */
+        s16 temp_input2, temp_low2, temp_high2; /* remote, combined */
+        s8 temp_crit1, temp_crit2;
+        u8 temp_hyst;
+        u8 alarms; /* bitvector */
+};
+
+/*
+ * Sysfs stuff
+ */
+
+#define show_temp(value, converter) \
+static ssize_t show_##value(struct device *dev, char *buf) \
+{ \
+        struct lm90_data *data = lm90_update_device(dev); \
+        return sprintf(buf, "%d\n", converter(data->value)); \
+}
+show_temp(temp_input1, TEMP1_FROM_REG);
+show_temp(temp_input2, TEMP2_FROM_REG);
+show_temp(temp_low1, TEMP1_FROM_REG);
+show_temp(temp_low2, TEMP2_FROM_REG);
+show_temp(temp_high1, TEMP1_FROM_REG);
+show_temp(temp_high2, TEMP2_FROM_REG);
+show_temp(temp_crit1, TEMP1_FROM_REG);
+show_temp(temp_crit2, TEMP1_FROM_REG);
+
+#define set_temp1(value, reg) \
+static ssize_t set_##value(struct device *dev, const char *buf, \
+        size_t count) \
+{ \
+        struct i2c_client *client = to_i2c_client(dev); \
+        struct lm90_data *data = i2c_get_clientdata(client); \
+        long val = simple_strtol(buf, NULL, 10); \
+ \
+        down(&data->update_lock); \
+        if (data->kind == adt7461) \
+                data->value = TEMP1_TO_REG_ADT7461(val); \
+        else \
+                data->value = TEMP1_TO_REG(val); \
+        i2c_smbus_write_byte_data(client, reg, data->value); \
+        up(&data->update_lock); \
+        return count; \
+}
+#define set_temp2(value, regh, regl) \
+static ssize_t set_##value(struct device *dev, const char *buf, \
+        size_t count) \
+{ \
+        struct i2c_client *client = to_i2c_client(dev); \
+        struct lm90_data *data = i2c_get_clientdata(client); \
+        long val = simple_strtol(buf, NULL, 10); \
+ \
+        down(&data->update_lock); \
+        if (data->kind == adt7461) \
+                data->value = TEMP2_TO_REG_ADT7461(val); \
+        else \
+                data->value = TEMP2_TO_REG(val); \
+        i2c_smbus_write_byte_data(client, regh, data->value >> 8); \
+        i2c_smbus_write_byte_data(client, regl, data->value & 0xff); \
+        up(&data->update_lock); \
+        return count; \
+}
+set_temp1(temp_low1, LM90_REG_W_LOCAL_LOW);
+set_temp2(temp_low2, LM90_REG_W_REMOTE_LOWH, LM90_REG_W_REMOTE_LOWL);
+set_temp1(temp_high1, LM90_REG_W_LOCAL_HIGH);
+set_temp2(temp_high2, LM90_REG_W_REMOTE_HIGHH, LM90_REG_W_REMOTE_HIGHL);
+set_temp1(temp_crit1, LM90_REG_W_LOCAL_CRIT);
+set_temp1(temp_crit2, LM90_REG_W_REMOTE_CRIT);
+
+#define show_temp_hyst(value, basereg) \
+static ssize_t show_##value(struct device *dev, char *buf) \
+{ \
+        struct lm90_data *data = lm90_update_device(dev); \
+        return sprintf(buf, "%d\n", TEMP1_FROM_REG(data->basereg) \
+                       - TEMP1_FROM_REG(data->temp_hyst)); \
+}
+show_temp_hyst(temp_hyst1, temp_crit1);
+show_temp_hyst(temp_hyst2, temp_crit2);
+
+static ssize_t set_temp_hyst1(struct device *dev, const char *buf,
+        size_t count)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct lm90_data *data = i2c_get_clientdata(client);
+        long val = simple_strtol(buf, NULL, 10);
+        long hyst;
+
+        down(&data->update_lock);
+        hyst = TEMP1_FROM_REG(data->temp_crit1) - val;
+        i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
+                                  HYST_TO_REG(hyst));
+        up(&data->update_lock);
+        return count;
+}
+
+static ssize_t show_alarms(struct device *dev, char *buf)
+{
+        struct lm90_data *data = lm90_update_device(dev);
+        return sprintf(buf, "%d\n", data->alarms);
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input1, NULL);
+static DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_input2, NULL);
+static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp_low1,
+        set_temp_low1);
+static DEVICE_ATTR(temp2_min, S_IWUSR | S_IRUGO, show_temp_low2,
+        set_temp_low2);
+static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_high1,
+        set_temp_high1);
+static DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp_high2,
+        set_temp_high2);
+static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp_crit1,
+        set_temp_crit1);
+static DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp_crit2,
+        set_temp_crit2);
+static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst1,
+        set_temp_hyst1);
+static DEVICE_ATTR(temp2_crit_hyst, S_IRUGO, show_temp_hyst2, NULL);
+static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
+
+/*
+ * Real code
+ */
+
+static int lm90_attach_adapter(struct i2c_adapter *adapter)
+{
+        if (!(adapter->class & I2C_CLASS_HWMON))
+                return 0;
+        return i2c_detect(adapter, &addr_data, lm90_detect);
+}
+
+/*
+ * The following function does more than just detection. If detection
+ * succeeds, it also registers the new chip.
+ */
+static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+        struct i2c_client *new_client;
+        struct lm90_data *data;
+        int err = 0;
+        const char *name = "";
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+                goto exit;
+
+        if (!(data = kmalloc(sizeof(struct lm90_data), GFP_KERNEL))) {
+                err = -ENOMEM;
+                goto exit;
+        }
+        memset(data, 0, sizeof(struct lm90_data));
+
+        /* The common I2C client data is placed right before the
+           LM90-specific data. */
+        new_client = &data->client;
+        i2c_set_clientdata(new_client, data);
+        new_client->addr = address;
+        new_client->adapter = adapter;
+        new_client->driver = &lm90_driver;
+        new_client->flags = 0;
+
+        /*
+         * Now we do the remaining detection. A negative kind means that
+         * the driver was loaded with no force parameter (default), so we
+         * must both detect and identify the chip. A zero kind means that
+         * the driver was loaded with the force parameter, the detection
+         * step shall be skipped. A positive kind means that the driver
+         * was loaded with the force parameter and a given kind of chip is
+         * requested, so both the detection and the identification steps
+         * are skipped.
+         */
+
+        /* Default to an LM90 if forced */
+        if (kind == 0)
+                kind = lm90;
+
+        if (kind < 0) { /* detection and identification */
+                u8 man_id, chip_id, reg_config1, reg_convrate;
+
+                man_id = i2c_smbus_read_byte_data(new_client,
+                         LM90_REG_R_MAN_ID);
+                chip_id = i2c_smbus_read_byte_data(new_client,
+                          LM90_REG_R_CHIP_ID);
+                reg_config1 = i2c_smbus_read_byte_data(new_client,
+                              LM90_REG_R_CONFIG1);
+                reg_convrate = i2c_smbus_read_byte_data(new_client,
+                               LM90_REG_R_CONVRATE);
+                
+                if (man_id == 0x01) { /* National Semiconductor */
+                        u8 reg_config2;
+
+                        reg_config2 = i2c_smbus_read_byte_data(new_client,
+                                      LM90_REG_R_CONFIG2);
+
+                        if ((reg_config1 & 0x2A) == 0x00
+                         && (reg_config2 & 0xF8) == 0x00
+                         && reg_convrate <= 0x09) {
+                                if (address == 0x4C
+                                 && (chip_id & 0xF0) == 0x20) { /* LM90 */
+                                        kind = lm90;
+                                } else
+                                if ((chip_id & 0xF0) == 0x30) { /* LM89/LM99 */
+                                        kind = lm99;
+                                } else
+                                if (address == 0x4C
+                                 && (chip_id & 0xF0) == 0x10) { /* LM86 */
+                                        kind = lm86;
+                                }
+                        }
+                } else
+                if (man_id == 0x41) { /* Analog Devices */
+                        if (address == 0x4C
+                         && (chip_id & 0xF0) == 0x40 /* ADM1032 */
+                         && (reg_config1 & 0x3F) == 0x00
+                         && reg_convrate <= 0x0A) {
+                                kind = adm1032;
+                        } else
+                        if (address == 0x4c
+                         && chip_id == 0x51 /* ADT7461 */
+                         && (reg_config1 & 0x1F) == 0x00 /* check compat mode */
+                         && reg_convrate <= 0x0A) {
+                                kind = adt7461;
+                        }
+                } else
+                if (man_id == 0x4D) { /* Maxim */
+                        /*
+                         * The Maxim variants do NOT have a chip_id register.
+                         * Reading from that address will return the last read
+                         * value, which in our case is those of the man_id
+                         * register. Likewise, the config1 register seems to
+                         * lack a low nibble, so the value will be those of the
+                         * previous read, so in our case those of the man_id
+                         * register.
+                         */
+                        if (chip_id == man_id
+                         && (reg_config1 & 0x1F) == (man_id & 0x0F)
+                         && reg_convrate <= 0x09) {
+                                kind = max6657;
+                        }
+                }
+
+                if (kind <= 0) { /* identification failed */
+                        dev_info(&adapter->dev,
+                            "Unsupported chip (man_id=0x%02X, "
+                            "chip_id=0x%02X).\n", man_id, chip_id);
+                        goto exit_free;
+                }
+        }
+
+        if (kind == lm90) {
+                name = "lm90";
+        } else if (kind == adm1032) {
+                name = "adm1032";
+        } else if (kind == lm99) {
+                name = "lm99";
+        } else if (kind == lm86) {
+                name = "lm86";
+        } else if (kind == max6657) {
+                name = "max6657";
+        } else if (kind == adt7461) {
+                name = "adt7461";
+        }
+
+        /* We can fill in the remaining client fields */
+        strlcpy(new_client->name, name, I2C_NAME_SIZE);
+        data->valid = 0;
+        data->kind = kind;
+        init_MUTEX(&data->update_lock);
+
+        /* Tell the I2C layer a new client has arrived */
+        if ((err = i2c_attach_client(new_client)))
+                goto exit_free;
+
+        /* Initialize the LM90 chip */
+        lm90_init_client(new_client);
+
+        /* Register sysfs hooks */
+        device_create_file(&new_client->dev, &dev_attr_temp1_input);
+        device_create_file(&new_client->dev, &dev_attr_temp2_input);
+        device_create_file(&new_client->dev, &dev_attr_temp1_min);
+        device_create_file(&new_client->dev, &dev_attr_temp2_min);
+        device_create_file(&new_client->dev, &dev_attr_temp1_max);
+        device_create_file(&new_client->dev, &dev_attr_temp2_max);
+        device_create_file(&new_client->dev, &dev_attr_temp1_crit);
+        device_create_file(&new_client->dev, &dev_attr_temp2_crit);
+        device_create_file(&new_client->dev, &dev_attr_temp1_crit_hyst);
+        device_create_file(&new_client->dev, &dev_attr_temp2_crit_hyst);
+        device_create_file(&new_client->dev, &dev_attr_alarms);
+
+        return 0;
+
+exit_free:
+        kfree(data);
+exit:
+        return err;
+}
+
+static void lm90_init_client(struct i2c_client *client)
+{
+        u8 config;
+
+        /*
+         * Start the conversions.
+         */
+        i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE,
+                                  5); /* 2 Hz */
+        config = i2c_smbus_read_byte_data(client, LM90_REG_R_CONFIG1);
+        if (config & 0x40)
+                i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1,
+                                          config & 0xBF); /* run */
+}
+
+static int lm90_detach_client(struct i2c_client *client)
+{
+        int err;
+
+        if ((err = i2c_detach_client(client))) {
+                dev_err(&client->dev, "Client deregistration failed, "
+                        "client not detached.\n");
+                return err;
+        }
+
+        kfree(i2c_get_clientdata(client));
+        return 0;
+}
+
+static struct lm90_data *lm90_update_device(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct lm90_data *data = i2c_get_clientdata(client);
+
+        down(&data->update_lock);
+
+        if (time_after(jiffies, data->last_updated + HZ * 2) || !data->valid) {
+                u8 oldh, newh;
+
+                dev_dbg(&client->dev, "Updating lm90 data.\n");
+                data->temp_input1 = i2c_smbus_read_byte_data(client,
+                                    LM90_REG_R_LOCAL_TEMP);
+                data->temp_high1 = i2c_smbus_read_byte_data(client,
+                                   LM90_REG_R_LOCAL_HIGH);
+                data->temp_low1 = i2c_smbus_read_byte_data(client,
+                                  LM90_REG_R_LOCAL_LOW);
+                data->temp_crit1 = i2c_smbus_read_byte_data(client,
+                                   LM90_REG_R_LOCAL_CRIT);
+                data->temp_crit2 = i2c_smbus_read_byte_data(client,
+                                   LM90_REG_R_REMOTE_CRIT);
+                data->temp_hyst = i2c_smbus_read_byte_data(client,
+                                  LM90_REG_R_TCRIT_HYST);
+
+                /*
+                 * There is a trick here. We have to read two registers to
+                 * have the remote sensor temperature, but we have to beware
+                 * a conversion could occur inbetween the readings. The
+                 * datasheet says we should either use the one-shot
+                 * conversion register, which we don't want to do (disables
+                 * hardware monitoring) or monitor the busy bit, which is
+                 * impossible (we can't read the values and monitor that bit
+                 * at the exact same time). So the solution used here is to
+                 * read the high byte once, then the low byte, then the high
+                 * byte again. If the new high byte matches the old one,
+                 * then we have a valid reading. Else we have to read the low
+                 * byte again, and now we believe we have a correct reading.
+                 */
+                oldh = i2c_smbus_read_byte_data(client,
+                       LM90_REG_R_REMOTE_TEMPH);
+                data->temp_input2 = i2c_smbus_read_byte_data(client,
+                                    LM90_REG_R_REMOTE_TEMPL);
+                newh = i2c_smbus_read_byte_data(client,
+                       LM90_REG_R_REMOTE_TEMPH);
+                if (newh != oldh) {
+                        data->temp_input2 = i2c_smbus_read_byte_data(client,
+                                            LM90_REG_R_REMOTE_TEMPL);
+#ifdef DEBUG
+                        oldh = i2c_smbus_read_byte_data(client,
+                               LM90_REG_R_REMOTE_TEMPH);
+                        /* oldh is actually newer */
+                        if (newh != oldh)
+                                dev_warn(&client->dev, "Remote temperature may be "
+                                         "wrong.\n");
+#endif
+                }
+                data->temp_input2 |= (newh << 8);
+
+                data->temp_high2 = (i2c_smbus_read_byte_data(client,
+                                   LM90_REG_R_REMOTE_HIGHH) << 8) +
+                                   i2c_smbus_read_byte_data(client,
+                                   LM90_REG_R_REMOTE_HIGHL);
+                data->temp_low2 = (i2c_smbus_read_byte_data(client,
+                                  LM90_REG_R_REMOTE_LOWH) << 8) +
+                                  i2c_smbus_read_byte_data(client,
+                                  LM90_REG_R_REMOTE_LOWL);
+                data->alarms = i2c_smbus_read_byte_data(client,
+                               LM90_REG_R_STATUS);
+
+                data->last_updated = jiffies;
+                data->valid = 1;
+        }
+
+        up(&data->update_lock);
+
+        return data;
+}
+
+static int __init sensors_lm90_init(void)
+{
+        return i2c_add_driver(&lm90_driver);
+}
+
+static void __exit sensors_lm90_exit(void)
+{
+        i2c_del_driver(&lm90_driver);
+}
+
+MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
+MODULE_DESCRIPTION("LM90/ADM1032 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_lm90_init);
+module_exit(sensors_lm90_exit);