RE: [RFC] [PATCH] Adding support for BMP085 pressure sensor.

From: Datta, Shubhrajyoti
Date: Mon Jun 14 2010 - 07:00:33 EST



> -----Original Message-----
> From: Stefan Schmidt [mailto:stefan@xxxxxxxxxxxxxxxxxx]
> Sent: Monday, June 14, 2010 4:06 PM
> To: Datta, Shubhrajyoti
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-input@xxxxxxxxxxxxxxx;
> christoph.mair@xxxxxxxxx
> 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.
I modified the initial version to use it as an input device an a few bug fixes and sent him the patch for his signoff. Also I have kept the copyright banner that he had.

However since it is not really a human input device I thought of making it an misc as it doesn't really justify a hwmon.
>
> regards
> Stefan Schmidt
>
> > Signed-off-by: Shubhrajyoti D <shubhrajyoti@xxxxxx>
> > ---
> > 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@xxxxxxxxx>
> > +
> > + 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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