/* Copyright (c) 2010 Christoph Mair <christoph.mair@gmail.com>
-
- This driver supports the bmp085 digital barometric pressure
- and temperature sensor from Bosch Sensortec. The datasheet
- is available from their website:
- http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf
-
- A pressure measurement is issued by reading from pressure0_input.
- The return value ranges from 30000 to 110000 pascal with a resulution
- of 1 pascal (0.01 millibar) which enables measurements from 9000m above
- to 500m below sea level.
-
- The temperature can be read from temp0_input. Values range from
- -400 to 850 representing the ambient temperature in degree celsius
- multiplied by 10.The resolution is 0.1 celsius.
-
- Because ambient pressure is temperature dependent, a temperature
- measurement will be executed automatically even if the user is reading
- from pressure0_input. This happens if the last temperature measurement
- has been executed more then one second ago.
-
- To decrease RMS noise from pressure measurements, the bmp085 can
- autonomously calculate the average of up to eight samples. This is
- set up by writing to the oversampling sysfs file. Accepted values
- are 0, 1, 2 and 3. 2^x when x is the value written to this file
- specifies the number of samples used to calculate the ambient pressure.
- RMS noise is specified with six pascal (without averaging) and decreases
- down to 3 pascal when using an oversampling setting of 3.
-
- 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.
-*/
-
+ * Copyright (c) 2012 Bosch Sensortec GmbH
+ * Copyright (c) 2012 Unixphere AB
+ *
+ * This driver supports the bmp085 digital barometric pressure
+ * and temperature sensor from Bosch Sensortec. The datasheet
+ * is available from their website:
+ * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf
+ *
+ * A pressure measurement is issued by reading from pressure0_input.
+ * The return value ranges from 30000 to 110000 pascal with a resulution
+ * of 1 pascal (0.01 millibar) which enables measurements from 9000m above
+ * to 500m below sea level.
+ *
+ * The temperature can be read from temp0_input. Values range from
+ * -400 to 850 representing the ambient temperature in degree celsius
+ * multiplied by 10.The resolution is 0.1 celsius.
+ *
+ * Because ambient pressure is temperature dependent, a temperature
+ * measurement will be executed automatically even if the user is reading
+ * from pressure0_input. This happens if the last temperature measurement
+ * has been executed more then one second ago.
+ *
+ * To decrease RMS noise from pressure measurements, the bmp085 can
+ * autonomously calculate the average of up to eight samples. This is
+ * set up by writing to the oversampling sysfs file. Accepted values
+ * are 0, 1, 2 and 3. 2^x when x is the value written to this file
+ * specifies the number of samples used to calculate the ambient pressure.
+ * RMS noise is specified with six pascal (without averaging) and decreases
+ * down to 3 pascal when using an oversampling setting of 3.
+ *
+ * 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/module.h>
+#include <linux/device.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/delay.h>
-
+#define BMP085_NAME "bmp085"
#define BMP085_I2C_ADDRESS 0x77
#define BMP085_CHIP_ID 0x55
#define BMP085_CALIBRATION_DATA_START 0xAA
#define BMP085_CALIBRATION_DATA_LENGTH 11 /* 16 bit values */
#define BMP085_CHIP_ID_REG 0xD0
-#define BMP085_VERSION_REG 0xD1
#define BMP085_CTRL_REG 0xF4
#define BMP085_TEMP_MEASUREMENT 0x2E
#define BMP085_PRESSURE_MEASUREMENT 0x34
#define BMP085_CONVERSION_REGISTER_XLSB 0xF8
#define BMP085_TEMP_CONVERSION_TIME 5
-#define BMP085_CLIENT_NAME "bmp085"
-
-
static const unsigned short normal_i2c[] = { BMP085_I2C_ADDRESS,
I2C_CLIENT_END };
s16 MB, MC, MD;
};
-
-/* Each client has this additional data */
struct bmp085_data {
- struct i2c_client *client;
- struct mutex lock;
- struct bmp085_calibration_data calibration;
- u32 raw_temperature;
- u32 raw_pressure;
- unsigned char oversampling_setting;
+ struct i2c_client *client;
+ struct mutex lock;
+ struct bmp085_calibration_data calibration;
+ u8 oversampling_setting;
+ u32 raw_temperature;
+ u32 raw_pressure;
+ u32 temp_measurement_period;
unsigned long last_temp_measurement;
- s32 b6; /* calculated temperature correction coefficient */
+ s32 b6; /* calculated temperature correction coefficient */
};
-
static s32 bmp085_read_calibration_data(struct i2c_client *client)
{
u16 tmp[BMP085_CALIBRATION_DATA_LENGTH];
struct bmp085_calibration_data *cali = &(data->calibration);
s32 status = i2c_smbus_read_i2c_block_data(client,
BMP085_CALIBRATION_DATA_START,
- BMP085_CALIBRATION_DATA_LENGTH*sizeof(u16),
+ (BMP085_CALIBRATION_DATA_LENGTH << 1),
(u8 *)tmp);
if (status < 0)
return status;
- if (status != BMP085_CALIBRATION_DATA_LENGTH*sizeof(u16))
+ if (status != (BMP085_CALIBRATION_DATA_LENGTH << 1))
return -EIO;
cali->AC1 = be16_to_cpu(tmp[0]);
return 0;
}
-
static s32 bmp085_update_raw_temperature(struct bmp085_data *data)
{
u16 tmp;
mutex_lock(&data->lock);
status = i2c_smbus_write_byte_data(data->client, BMP085_CTRL_REG,
BMP085_TEMP_MEASUREMENT);
- if (status != 0) {
+ if (status < 0) {
dev_err(&data->client->dev,
"Error while requesting temperature measurement.\n");
goto exit;
mutex_lock(&data->lock);
status = i2c_smbus_write_byte_data(data->client, BMP085_CTRL_REG,
- BMP085_PRESSURE_MEASUREMENT + (data->oversampling_setting<<6));
- if (status != 0) {
+ BMP085_PRESSURE_MEASUREMENT +
+ (data->oversampling_setting << 6));
+ if (status < 0) {
dev_err(&data->client->dev,
"Error while requesting pressure measurement.\n");
goto exit;
return status;
}
-
/*
* This function starts the temperature measurement and returns the value
* in tenth of a degree celsius.
int status;
status = bmp085_update_raw_temperature(data);
- if (status != 0)
+ if (status < 0)
goto exit;
x1 = ((data->raw_temperature - cali->AC6) * cali->AC5) >> 15;
/*
* This function starts the pressure measurement and returns the value
* in millibar. Since the pressure depends on the ambient temperature,
- * a temperature measurement is executed if the last known value is older
- * than one second.
+ * a temperature measurement is executed according to the given temperature
+ * measurement period (default is 1 sec boundary). This period could vary
+ * and needs to be adjusted according to the sensor environment, i.e. if big
+ * temperature variations then the temperature needs to be read out often.
*/
static s32 bmp085_get_pressure(struct bmp085_data *data, int *pressure)
{
int status;
/* alt least every second force an update of the ambient temperature */
- if (data->last_temp_measurement == 0 ||
- time_is_before_jiffies(data->last_temp_measurement + 1*HZ)) {
+ if ((data->last_temp_measurement == 0) ||
+ time_is_before_jiffies(data->last_temp_measurement + 1*HZ)) {
status = bmp085_get_temperature(data, NULL);
- if (status != 0)
- goto exit;
+ if (status < 0)
+ return status;
}
status = bmp085_update_raw_pressure(data);
- if (status != 0)
- goto exit;
+ if (status < 0)
+ return status;
x1 = (data->b6 * data->b6) >> 12;
x1 *= cali->B2;
*pressure = p;
-exit:
- return status;
+ return 0;
}
/*
* This function sets the chip-internal oversampling. Valid values are 0..3.
* The chip will use 2^oversampling samples for internal averaging.
* This influences the measurement time and the accuracy; larger values
- * increase both. The datasheet gives on overview on how measurement time,
+ * increase both. The datasheet gives an overview on how measurement time,
* accuracy and noise correlate.
*/
static void bmp085_set_oversampling(struct bmp085_data *data,
struct i2c_client *client = to_i2c_client(dev);
struct bmp085_data *data = i2c_get_clientdata(client);
unsigned long oversampling;
- int success = strict_strtoul(buf, 10, &oversampling);
- if (success == 0) {
+ int err = kstrtoul(buf, 10, &oversampling);
+
+ if (err == 0) {
+ mutex_lock(&data->lock);
bmp085_set_oversampling(data, oversampling);
+ mutex_unlock(&data->lock);
return count;
}
- return success;
+
+ return err;
}
static ssize_t show_oversampling(struct device *dev,
{
struct i2c_client *client = to_i2c_client(dev);
struct bmp085_data *data = i2c_get_clientdata(client);
+
return sprintf(buf, "%u\n", bmp085_get_oversampling(data));
}
static DEVICE_ATTR(oversampling, S_IWUSR | S_IRUGO,
struct bmp085_data *data = i2c_get_clientdata(client);
status = bmp085_get_temperature(data, &temperature);
- if (status != 0)
+ if (status < 0)
return status;
else
return sprintf(buf, "%d\n", temperature);
struct bmp085_data *data = i2c_get_clientdata(client);
status = bmp085_get_pressure(data, &pressure);
- if (status != 0)
+ if (status < 0)
return status;
else
return sprintf(buf, "%d\n", pressure);
static int bmp085_init_client(struct i2c_client *client)
{
- unsigned char version;
- int status;
struct bmp085_data *data = i2c_get_clientdata(client);
+ int status = bmp085_read_calibration_data(client);
+
+ if (status < 0)
+ return status;
+
data->client = client;
- status = bmp085_read_calibration_data(client);
- if (status != 0)
- goto exit;
- version = i2c_smbus_read_byte_data(client, BMP085_VERSION_REG);
data->last_temp_measurement = 0;
+ data->temp_measurement_period = 1*HZ;
data->oversampling_setting = 3;
mutex_init(&data->lock);
- dev_info(&data->client->dev, "BMP085 ver. %d.%d found.\n",
- (version & 0x0F), (version & 0xF0) >> 4);
-exit:
- return status;
+
+ return 0;
}
static int __devinit bmp085_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
+ const struct i2c_device_id *id)
{
struct bmp085_data *data;
int err = 0;
goto exit;
}
- /* default settings after POR */
- data->oversampling_setting = 0x00;
-
i2c_set_clientdata(client, data);
/* Initialize the BMP085 chip */
err = bmp085_init_client(client);
- if (err != 0)
+ if (err < 0)
goto exit_free;
/* Register sysfs hooks */
if (err)
goto exit_free;
- dev_info(&data->client->dev, "Successfully initialized bmp085!\n");
- goto exit;
+ dev_info(&client->dev, "Successfully initialized %s!\n", BMP085_NAME);
+
+ return 0;
exit_free:
kfree(data);
static int __devexit bmp085_remove(struct i2c_client *client)
{
+ struct bmp085_data *data = i2c_get_clientdata(client);
+
sysfs_remove_group(&client->dev.kobj, &bmp085_attr_group);
- kfree(i2c_get_clientdata(client));
+ kfree(data);
+
return 0;
}
static const struct i2c_device_id bmp085_id[] = {
- { "bmp085", 0 },
+ { BMP085_NAME, 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, bmp085_id);
static struct i2c_driver bmp085_driver = {
.driver = {
.owner = THIS_MODULE,
- .name = "bmp085"
+ .name = BMP085_NAME
},
.id_table = bmp085_id,
.probe = bmp085_probe,
module_i2c_driver(bmp085_driver);
-MODULE_AUTHOR("Christoph Mair <christoph.mair@gmail.com");
+MODULE_AUTHOR("Christoph Mair <christoph.mair@gmail.com>");
MODULE_DESCRIPTION("BMP085 driver");
MODULE_LICENSE("GPL");
projects / deliverable / linux.git / commitdiff
