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Message-ID: <20100614103548.GA19679@excalibur.local>
Date: Mon, 14 Jun 2010 12:35:48 +0200
From: Stefan Schmidt <stefan@...enfreihafen.org>
To: "Datta, Shubhrajyoti" <shubhrajyoti@...com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
christoph.mair@...il.com
Subject: Re: [RFC] [PATCH] Adding support for BMP085 pressure sensor.
Hello.
On Mon, 2010-06-14 at 15:43, Datta, Shubhrajyoti wrote:
> Adding support for BMP085 pressure sensor.
> The interface of the device is I2C.
> The driver is based on a version initially written by Christoph
> Mair.
Did you coordinate with Christoph on this driver? I used it myself and the last
time I talked to Christoph he was planning to brining it mainline himself. Added
him to cc to keep him in the loop.
regards
Stefan Schmidt
> Signed-off-by: Shubhrajyoti D <shubhrajyoti@...com>
> ---
> drivers/misc/bmp085.c | 333 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 333 insertions(+), 0 deletions(-)
> create mode 100755 drivers/misc/bmp085.c
>
> diff --git a/drivers/misc/bmp085.c b/drivers/misc/bmp085.c
> new file mode 100755
> index 0000000..fab2480
> --- /dev/null
> +++ b/drivers/misc/bmp085.c
> @@ -0,0 +1,333 @@
> +/* Copyright (c) 2009 Christoph Mair <christoph.mair@...il.com>
> +
> + 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/i2c.h>
> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/jiffies.h>
> +
> +#define BMP085_I2C_ADDRESS 0x77
> +#define BMP085_CALIBRATION_DATA_START 0xAA
> +#define BMP085_CALIBRATION_DATA_LENGTH 22
> +#define BMP085_CHIP_ID_REG 0xD0
> +#define BMP085_VERSION_REG 0xD1
> +#define BMP085_CHIP_ID 0x55
> +#define BMP085_CTRL_REG 0xF4
> +#define BMP085_TEMP_REG 0x2E
> +#define BMP085_PRESSURE_OSRS0 0x34
> +#define BMP085_MSB 0xF6
> +#define BMP085_LSB 0xF7
> +#define BMP085_XLSB 0xF8
> +#define BMP085_TEMP_CONV_TIME 5
> +
> +struct bmp085_calibration_data {
> + s16 AC1, AC2, AC3;
> + u16 AC4, AC5, AC6;
> + s16 B1, B2;
> + 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;
> + unsigned char oversampling_setting;
> + s32 b6; /* calculated temperature correction coefficient */
> +};
> +
> +static void bmp085_init_client(struct i2c_client *client);
> +
> +static s32 bmp085_get_calibration_data(struct i2c_client *client)
> +{
> + u8 tmp[BMP085_CALIBRATION_DATA_LENGTH];
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + struct bmp085_calibration_data *cali = &(data->calibration);
> + s32 status = i2c_smbus_read_i2c_block_data(client,
> + BMP085_CALIBRATION_DATA_START,
> + BMP085_CALIBRATION_DATA_LENGTH, tmp);
> +
> + cali->AC1 = (tmp[0] << 8) | tmp[1];
> + cali->AC2 = (tmp[2] << 8) | tmp[3];
> + cali->AC3 = (tmp[4] << 8) | tmp[5];
> + cali->AC4 = (tmp[6] << 8) | tmp[7];
> + cali->AC5 = (tmp[8] << 8) | tmp[9];
> + cali->AC6 = (tmp[10] << 8) | tmp[11];
> +
> + /*parameters B1,B2*/
> + cali->B1 = (tmp[12] << 8) | tmp[13];
> + cali->B2 = (tmp[14] << 8) | tmp[15];
> +
> + /*parameters MB,MC,MD*/
> + cali->MB = (tmp[16] << 8) | tmp[17];
> + cali->MC = (tmp[18] << 8) | tmp[19];
> + cali->MD = (tmp[20] << 8) | tmp[21];
> + return status;
> +}
> +
> +static s32 bmp085_get_temperature(struct i2c_client *client)
> +{
> + u16 temperature = 0x00;
> + u8 tmp[2];
> + s32 status = i2c_smbus_write_byte_data(client, BMP085_CTRL_REG,
> + BMP085_TEMP_REG);
> + if (status != 0) {
> + dev_err(&client->dev, "bmp085: Error requesting\
> + temperature measurement.\n");
> + return status;
> + }
> + msleep(BMP085_TEMP_CONV_TIME);
> +
> + i2c_smbus_read_i2c_block_data(client, BMP085_MSB, 2, tmp);
> + /* next temperature measurement is needed in one second */
> + temperature = (tmp[0] << 8) + tmp[1];
> + pr_info("temperature: %u\n", temperature);
> + return temperature;
> +}
> +
> +static s32 bmp085_read_pressure(struct i2c_client *client, u32 *pressure)
> +{
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + u8 tmp[3];
> + s32 status;
> +
> + status = i2c_smbus_write_byte_data(client, BMP085_CTRL_REG,
> + BMP085_PRESSURE_OSRS0 + (data->oversampling_setting<<6));
> + if (status != 0)
> + return status;
> +
> + /* wait for the end of conversion */
> + msleep(2+(3 << data->oversampling_setting));
> +
> + status = i2c_smbus_read_i2c_block_data(client, BMP085_MSB, 0x03, tmp);
> + /* swap positions to correct the MSB/LSB positions*/
> + *pressure = (tmp[0] << 16) | (tmp[1] << 8) | tmp[2];
> + *pressure = *pressure >> (8-data->oversampling_setting);
> + return status;
> +}
> +
> +/* sysfs callbacks */
> +static ssize_t set_oversampling(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf,
> + size_t count)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + data->oversampling_setting = simple_strtoul(buf, NULL, 10);
> + if (data->oversampling_setting > 3)
> + data->oversampling_setting = 3;
> + return count;
> +}
> +
> +static ssize_t show_oversampling(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + return sprintf(buf, "%u\n", data->oversampling_setting);
> +}
> +static DEVICE_ATTR(oversampling, S_IWUSR | S_IRUGO,
> + show_oversampling, set_oversampling);
> +
> +static void bmp085_read_temperature(struct i2c_client *client, s32 *buf)
> +{
> + s32 raw_temp, x1 , x2;
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + struct bmp085_calibration_data *cali = &data->calibration;
> +
> + raw_temp = bmp085_get_temperature(client);
> + x1 = ((raw_temp - cali->AC6) * cali->AC5) >> 15;
> + x2 = (cali->MC << 11) / (x1 + cali->MD);
> + data->b6 = x1 + x2 - 4000;
> + *buf = ((x1+x2+8) >> 4) ;
> +}
> +
> +static int bmp085_read_sensor(struct bmp085_data *bmp085,
> + s32 *pressure,
> + s32 *temp)
> +{
> +
> + struct i2c_client *client = bmp085->client;
> + struct bmp085_data *data = i2c_get_clientdata(client);
> + struct bmp085_calibration_data *cali = &data->calibration;
> + s32 x1, x2, x3, b3;
> + u32 b4, b7;
> + s32 p;
> + unsigned int raw_pressure=0;
> + s32 raw_temp;
> +
> + bmp085_read_temperature(client, &raw_temp);
> + *temp = raw_temp ;
> + bmp085_read_pressure(client, &raw_pressure);
> +
> + 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) >> 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)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;
> +}
> +static ssize_t show_temperature(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + return sprintf(buf, "%d\n", bmp085_get_temperature(client));
> +}
> +static DEVICE_ATTR(temperature, S_IRUGO, show_temperature, NULL);
> +
> +
> +static ssize_t show_pressure(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct bmp085_data *bmp085 = i2c_get_clientdata(client);
> + s32 pressure_read, temperature;
> +
> + bmp085_read_sensor(bmp085, &pressure_read, &temperature);
> +
> + return sprintf(buf, "%d\n", pressure_read);
> +}
> +static DEVICE_ATTR(pressure, S_IRUGO, show_pressure, NULL);
> +
> +static struct attribute *bmp085_attributes[] = {
> + &dev_attr_oversampling.attr,
> + &dev_attr_pressure.attr,
> + &dev_attr_temperature.attr,
> + NULL
> +};
> +
> +static const struct attribute_group bmp085_attr_group = {
> + .attrs = bmp085_attributes,
> +};
> +
> +static int bmp085_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct bmp085_data *bmp085_data;
> + int err;
> +
> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> + dev_dbg(&client->dev, "adapter doesn't support I2C\n");
> + return -ENODEV;
> + }
> +
> + bmp085_data = kzalloc(sizeof(struct bmp085_data), GFP_KERNEL);
> + if (!bmp085_data) {
> + err = -ENOMEM;
> + goto exit;
> + }
> + bmp085_data->client = client;
> +
> + /* default settings after POR */
> + bmp085_data->oversampling_setting = 0x00;
> +
> + i2c_set_clientdata(client, bmp085_data);
> +
> + /* Initialize the BMP085 chip */
> + bmp085_init_client(client);
> +
> + /* Register sysfs hooks */
> + err = sysfs_create_group(&client->dev.kobj, &bmp085_attr_group);
> + if (err)
> + dev_err(&client->dev,
> + "failed to create sysfs entries\n");
> +
> + return 0;
> +
> +exit:
> + return err;
> +}
> +
> +static int bmp085_remove(struct i2c_client *client)
> +{
> + struct bmp085_data *bmp085 = i2c_get_clientdata(client);
> +
> + pr_info("bmp085 remove\n");
> + sysfs_remove_group(&client->dev.kobj, &bmp085_attr_group);
> + kfree(bmp085);
> + return 0;
> +}
> +
> +static void bmp085_init_client(struct i2c_client *client)
> +{
> + u8 version;
> + struct bmp085_data *data = i2c_get_clientdata(client);
> +
> + bmp085_get_calibration_data(client);
> + version = i2c_smbus_read_byte_data(client, BMP085_VERSION_REG);
> + data->oversampling_setting = 3;
> + mutex_init(&data->lock);
> + pr_info("BMP085 ver. %d.%d initialized\n",
> + (version & 0x0F), (version & 0xF0) >> 4);
> +}
> +
> +static const struct i2c_device_id bmp085_id[] = {
> + { "bmp085", 0 },
> + { }
> +};
> +
> +static struct i2c_driver bmp085_driver = {
> + .driver = {
> + .name = "bmp085",
> + .owner = THIS_MODULE,
> + },
> + .probe = bmp085_probe,
> + .remove = bmp085_remove,
> + .id_table = bmp085_id,
> +};
> +
> +static int __init bmp085_init(void)
> +{
> + return i2c_add_driver(&bmp085_driver);
> +}
> +
> +static void __exit bmp085_exit(void)
> +{
> + i2c_del_driver(&bmp085_driver);
> +}
> +
> +MODULE_AUTHOR("Christoph Mair, Shubhrajyoti");
> +MODULE_DESCRIPTION("BMP085 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(bmp085_init);
> +module_exit(bmp085_exit);
> +
> --
> 1.5.4.7
>
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