From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- drivers/misc/bmp085.c | 506 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 506 insertions(+) create mode 100644 drivers/misc/bmp085.c (limited to 'drivers/misc/bmp085.c') diff --git a/drivers/misc/bmp085.c b/drivers/misc/bmp085.c new file mode 100644 index 000000000..9b313f781 --- /dev/null +++ b/drivers/misc/bmp085.c @@ -0,0 +1,506 @@ +/* Copyright (c) 2010 Christoph Mair + * Copyright (c) 2012 Bosch Sensortec GmbH + * Copyright (c) 2012 Unixphere AB + * + * This driver supports the bmp085 and bmp18x digital barometric pressure + * and temperature sensors from Bosch Sensortec. The datasheets + * are available from their website: + * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf + * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP180-DS000-07.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 +#include +#include +#include +#include "bmp085.h" +#include +#include +#include + +#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_CTRL_REG 0xF4 +#define BMP085_TEMP_MEASUREMENT 0x2E +#define BMP085_PRESSURE_MEASUREMENT 0x34 +#define BMP085_CONVERSION_REGISTER_MSB 0xF6 +#define BMP085_CONVERSION_REGISTER_LSB 0xF7 +#define BMP085_CONVERSION_REGISTER_XLSB 0xF8 +#define BMP085_TEMP_CONVERSION_TIME 5 + +struct bmp085_calibration_data { + s16 AC1, AC2, AC3; + u16 AC4, AC5, AC6; + s16 B1, B2; + s16 MB, MC, MD; +}; + +struct bmp085_data { + struct device *dev; + struct regmap *regmap; + 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; + u8 chip_id; + s32 b6; /* calculated temperature correction coefficient */ + int irq; + struct completion done; +}; + +static irqreturn_t bmp085_eoc_isr(int irq, void *devid) +{ + struct bmp085_data *data = devid; + + complete(&data->done); + + return IRQ_HANDLED; +} + +static s32 bmp085_read_calibration_data(struct bmp085_data *data) +{ + u16 tmp[BMP085_CALIBRATION_DATA_LENGTH]; + struct bmp085_calibration_data *cali = &(data->calibration); + s32 status = regmap_bulk_read(data->regmap, + BMP085_CALIBRATION_DATA_START, (u8 *)tmp, + (BMP085_CALIBRATION_DATA_LENGTH << 1)); + if (status < 0) + return status; + + cali->AC1 = be16_to_cpu(tmp[0]); + cali->AC2 = be16_to_cpu(tmp[1]); + cali->AC3 = be16_to_cpu(tmp[2]); + cali->AC4 = be16_to_cpu(tmp[3]); + cali->AC5 = be16_to_cpu(tmp[4]); + cali->AC6 = be16_to_cpu(tmp[5]); + cali->B1 = be16_to_cpu(tmp[6]); + cali->B2 = be16_to_cpu(tmp[7]); + cali->MB = be16_to_cpu(tmp[8]); + cali->MC = be16_to_cpu(tmp[9]); + cali->MD = be16_to_cpu(tmp[10]); + return 0; +} + +static s32 bmp085_update_raw_temperature(struct bmp085_data *data) +{ + u16 tmp; + s32 status; + + mutex_lock(&data->lock); + + init_completion(&data->done); + + status = regmap_write(data->regmap, BMP085_CTRL_REG, + BMP085_TEMP_MEASUREMENT); + if (status < 0) { + dev_err(data->dev, + "Error while requesting temperature measurement.\n"); + goto exit; + } + wait_for_completion_timeout(&data->done, 1 + msecs_to_jiffies( + BMP085_TEMP_CONVERSION_TIME)); + + status = regmap_bulk_read(data->regmap, BMP085_CONVERSION_REGISTER_MSB, + &tmp, sizeof(tmp)); + if (status < 0) { + dev_err(data->dev, + "Error while reading temperature measurement result\n"); + goto exit; + } + data->raw_temperature = be16_to_cpu(tmp); + data->last_temp_measurement = jiffies; + status = 0; /* everything ok, return 0 */ + +exit: + mutex_unlock(&data->lock); + return status; +} + +static s32 bmp085_update_raw_pressure(struct bmp085_data *data) +{ + u32 tmp = 0; + s32 status; + + mutex_lock(&data->lock); + + init_completion(&data->done); + + status = regmap_write(data->regmap, BMP085_CTRL_REG, + BMP085_PRESSURE_MEASUREMENT + + (data->oversampling_setting << 6)); + if (status < 0) { + dev_err(data->dev, + "Error while requesting pressure measurement.\n"); + goto exit; + } + + /* wait for the end of conversion */ + wait_for_completion_timeout(&data->done, 1 + msecs_to_jiffies( + 2+(3 << data->oversampling_setting))); + /* copy data into a u32 (4 bytes), but skip the first byte. */ + status = regmap_bulk_read(data->regmap, BMP085_CONVERSION_REGISTER_MSB, + ((u8 *)&tmp)+1, 3); + if (status < 0) { + dev_err(data->dev, + "Error while reading pressure measurement results\n"); + goto exit; + } + data->raw_pressure = be32_to_cpu((tmp)); + data->raw_pressure >>= (8-data->oversampling_setting); + status = 0; /* everything ok, return 0 */ + +exit: + mutex_unlock(&data->lock); + return status; +} + +/* + * This function starts the temperature measurement and returns the value + * in tenth of a degree celsius. + */ +static s32 bmp085_get_temperature(struct bmp085_data *data, int *temperature) +{ + struct bmp085_calibration_data *cali = &data->calibration; + long x1, x2; + int status; + + status = bmp085_update_raw_temperature(data); + if (status < 0) + goto exit; + + x1 = ((data->raw_temperature - cali->AC6) * cali->AC5) >> 15; + x2 = (cali->MC << 11) / (x1 + cali->MD); + data->b6 = x1 + x2 - 4000; + /* if NULL just update b6. Used for pressure only measurements */ + if (temperature != NULL) + *temperature = (x1+x2+8) >> 4; + +exit: + return status; +} + +/* + * 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 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) +{ + struct bmp085_calibration_data *cali = &data->calibration; + s32 x1, x2, x3, b3; + u32 b4, b7; + s32 p; + 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)) { + status = bmp085_get_temperature(data, NULL); + if (status < 0) + return status; + } + + status = bmp085_update_raw_pressure(data); + if (status < 0) + return status; + + x1 = (data->b6 * data->b6) >> 12; + x1 *= cali->B2; + x1 >>= 11; + + x2 = cali->AC2 * data->b6; + x2 >>= 11; + + x3 = x1 + x2; + + b3 = (((((s32)cali->AC1) * 4 + x3) << data->oversampling_setting) + 2); + b3 >>= 2; + + x1 = (cali->AC3 * data->b6) >> 13; + x2 = (cali->B1 * ((data->b6 * data->b6) >> 12)) >> 16; + x3 = (x1 + x2 + 2) >> 2; + b4 = (cali->AC4 * (u32)(x3 + 32768)) >> 15; + + b7 = ((u32)data->raw_pressure - b3) * + (50000 >> data->oversampling_setting); + p = ((b7 < 0x80000000) ? ((b7 << 1) / b4) : ((b7 / b4) * 2)); + + x1 = p >> 8; + x1 *= x1; + x1 = (x1 * 3038) >> 16; + x2 = (-7357 * p) >> 16; + p += (x1 + x2 + 3791) >> 4; + + *pressure = p; + + 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 an overview on how measurement time, + * accuracy and noise correlate. + */ +static void bmp085_set_oversampling(struct bmp085_data *data, + unsigned char oversampling) +{ + if (oversampling > 3) + oversampling = 3; + data->oversampling_setting = oversampling; +} + +/* + * Returns the currently selected oversampling. Range: 0..3 + */ +static unsigned char bmp085_get_oversampling(struct bmp085_data *data) +{ + return data->oversampling_setting; +} + +/* sysfs callbacks */ +static ssize_t set_oversampling(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct bmp085_data *data = dev_get_drvdata(dev); + unsigned long oversampling; + 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 err; +} + +static ssize_t show_oversampling(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct bmp085_data *data = dev_get_drvdata(dev); + + return sprintf(buf, "%u\n", bmp085_get_oversampling(data)); +} +static DEVICE_ATTR(oversampling, S_IWUSR | S_IRUGO, + show_oversampling, set_oversampling); + + +static ssize_t show_temperature(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int temperature; + int status; + struct bmp085_data *data = dev_get_drvdata(dev); + + status = bmp085_get_temperature(data, &temperature); + if (status < 0) + return status; + else + return sprintf(buf, "%d\n", temperature); +} +static DEVICE_ATTR(temp0_input, S_IRUGO, show_temperature, NULL); + + +static ssize_t show_pressure(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int pressure; + int status; + struct bmp085_data *data = dev_get_drvdata(dev); + + status = bmp085_get_pressure(data, &pressure); + if (status < 0) + return status; + else + return sprintf(buf, "%d\n", pressure); +} +static DEVICE_ATTR(pressure0_input, S_IRUGO, show_pressure, NULL); + + +static struct attribute *bmp085_attributes[] = { + &dev_attr_temp0_input.attr, + &dev_attr_pressure0_input.attr, + &dev_attr_oversampling.attr, + NULL +}; + +static const struct attribute_group bmp085_attr_group = { + .attrs = bmp085_attributes, +}; + +int bmp085_detect(struct device *dev) +{ + struct bmp085_data *data = dev_get_drvdata(dev); + unsigned int id; + int ret; + + ret = regmap_read(data->regmap, BMP085_CHIP_ID_REG, &id); + if (ret < 0) + return ret; + + if (id != data->chip_id) + return -ENODEV; + + return 0; +} +EXPORT_SYMBOL_GPL(bmp085_detect); + +static void bmp085_get_of_properties(struct bmp085_data *data) +{ +#ifdef CONFIG_OF + struct device_node *np = data->dev->of_node; + u32 prop; + + if (!np) + return; + + if (!of_property_read_u32(np, "chip-id", &prop)) + data->chip_id = prop & 0xff; + + if (!of_property_read_u32(np, "temp-measurement-period", &prop)) + data->temp_measurement_period = (prop/100)*HZ; + + if (!of_property_read_u32(np, "default-oversampling", &prop)) + data->oversampling_setting = prop & 0xff; +#endif +} + +static int bmp085_init_client(struct bmp085_data *data) +{ + int status = bmp085_read_calibration_data(data); + + if (status < 0) + return status; + + /* default settings */ + data->chip_id = BMP085_CHIP_ID; + data->last_temp_measurement = 0; + data->temp_measurement_period = 1*HZ; + data->oversampling_setting = 3; + + bmp085_get_of_properties(data); + + mutex_init(&data->lock); + + return 0; +} + +struct regmap_config bmp085_regmap_config = { + .reg_bits = 8, + .val_bits = 8 +}; +EXPORT_SYMBOL_GPL(bmp085_regmap_config); + +int bmp085_probe(struct device *dev, struct regmap *regmap, int irq) +{ + struct bmp085_data *data; + int err = 0; + + data = kzalloc(sizeof(struct bmp085_data), GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto exit; + } + + dev_set_drvdata(dev, data); + data->dev = dev; + data->regmap = regmap; + data->irq = irq; + + if (data->irq > 0) { + err = devm_request_irq(dev, data->irq, bmp085_eoc_isr, + IRQF_TRIGGER_RISING, "bmp085", + data); + if (err < 0) + goto exit_free; + } + + /* Initialize the BMP085 chip */ + err = bmp085_init_client(data); + if (err < 0) + goto exit_free; + + err = bmp085_detect(dev); + if (err < 0) { + dev_err(dev, "%s: chip_id failed!\n", BMP085_NAME); + goto exit_free; + } + + /* Register sysfs hooks */ + err = sysfs_create_group(&dev->kobj, &bmp085_attr_group); + if (err) + goto exit_free; + + dev_info(dev, "Successfully initialized %s!\n", BMP085_NAME); + + return 0; + +exit_free: + kfree(data); +exit: + return err; +} +EXPORT_SYMBOL_GPL(bmp085_probe); + +int bmp085_remove(struct device *dev) +{ + struct bmp085_data *data = dev_get_drvdata(dev); + + sysfs_remove_group(&data->dev->kobj, &bmp085_attr_group); + kfree(data); + + return 0; +} +EXPORT_SYMBOL_GPL(bmp085_remove); + +MODULE_AUTHOR("Christoph Mair "); +MODULE_DESCRIPTION("BMP085 driver"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3-54-g00ecf