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Message-ID: <fd6b62c10908140405q63de0229l57b16df72175d119@mail.gmail.com>
Date: Fri, 14 Aug 2009 19:05:26 +0800
From: XingChao Wang <wxc200@...il.com>
To: Chris Verges <chrisv@...erswitching.com>
Cc: linux-kernel@...r.kernel.org, lm-sensors@...sensors.org
Subject: Re: [PATCH] adxl345 accelerometer hwmon driver
2009/7/2 Chris Verges <chrisv@...erswitching.com>
>
> Hi kernel hackers,
>
> Here is a patch that adds support to the Linux kernel for Analog
> Device's ADXL345 chip. It is an accelerometer that uses I2C and HWMON.
> When I looked into the MAINTAINERS file for the appropriate list, the
> "Orphan" status of "Hardware Monitoring" confused me as to the proper
> list for this patch ... please let me know if I need to forward it
> elsewhere.
>
> ALPHA Warning: THIS CODE COMPILES WITHOUT ERROR, BUT HAS NOT BEEN TESTED
> YET.
>
> I'd appreciate feedback from those who have the time/interest to help!
> Code review would be great, someone with hardware for testing would be
> excellent.
>
> Thanks,
> Chris
>
>
> --- PATCH BELOW ---
>
> Signed-off-by: Chris Verges <chrisv@...erswitching.com>
> Index: drivers/hwmon/Makefile
> ===================================================================
> --- linux-2.6.29.3-orig/drivers/hwmon/Makefile (revision 33)
> +++ linux-2.6.29.3/drivers/hwmon/Makefile (revision 49)
> @@ -29,6 +29,7 @@
> obj-$(CONFIG_SENSORS_ADT7470) += adt7470.o
> obj-$(CONFIG_SENSORS_ADT7473) += adt7473.o
> obj-$(CONFIG_SENSORS_ADT7475) += adt7475.o
> +obj-$(CONFIG_SENSORS_ADXL345) += adxl345.o
>
> obj-$(CONFIG_SENSORS_APPLESMC) += applesmc.o
> obj-$(CONFIG_SENSORS_AMS) += ams/
> Index: drivers/hwmon/Kconfig
> ===================================================================
> --- linux-2.6.29.3-orig/drivers/hwmon/Kconfig (revision 33)
> +++ linux-2.6.29.3/drivers/hwmon/Kconfig (revision 49)
> @@ -199,6 +199,16 @@
> This driver can also be build as a module. If so, the module
> will be called adt7475.
>
> +config SENSORS_ADXL345
> + tristate "Analog Devices ADXL345"
> + depends on I2C && EXPERIMENTAL
> + help
> + If you say yes here, you get support for the Analog Devices
> + ADXL345 digital accelerometer chip.
> +
> + This driver can also be build as a module. If so, the module
> + will be called adxl345.
> +
> config SENSORS_K8TEMP
> tristate "AMD Athlon64/FX or Opteron temperature sensor"
> depends on X86 && PCI && EXPERIMENTAL
> Index: drivers/hwmon/adxl345.c
> ===================================================================
> --- linux-2.6.29.3-orig/drivers/hwmon/adxl345.c (revision 0)
> +++ linux-2.6.29.3/drivers/hwmon/adxl345.c (revision 49)
> @@ -0,0 +1,521 @@
> +/*
> + * A hwmon driver for the Analog Devices ADXL345
> + *
> + * Copyright (c) 2009 Cyber Switching, Inc.
> + * Author: Robert Mehranfar <robertme@...thlink.net>
> + *
> + * 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/init.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/hwmon-vid.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/kernel.h>
> +
> +#define DRV_NAME "adxl345"
> +#define DRV_VERSION "0.1"
> +
> +#define SIMULATE 1
> +
> +/*
> + * The ADXL345 registers
> + */
> +#define ADXL345_REG_DEV_ID 0x00
> +#define ADXL345_REG_OFS(nr) (0x1E + (nr))
> +#define ADXL345_REG_DATA(nr) (0x32 + (nr))
> +#define ADXL345_REG_DATA_FORMAT 0x31
> +
> +/*
> + * See ADXL345 specification
> + */
> +#define OFFSET_SCALE_FACTOR_WHOLE 15
> +#define OFFSET_SCALE_FACTOR_FRACTIONAL 6
> +
> +#define MAX_OFFSET 1988
> +#define MIN_OFFSET -1998
> +
> +/*
> + * Based on 10-bit resolution +/-16 range set in the DATA FORMAT
> register
> + */
> +#define DATA_SCALE_FACTOR_WHOLE 15
> +#define DATA_SCALE_FACTOR_FRACTIONAL 6
> +#define NUMBER_OF_AXES 3
> +
> +#define X_AXIS 0
> +#define Y_AXIS 1
> +#define Z_AXIS 2
> +
> +/* Position in the sysfs attribute array */
> +#define X_AXIS_ATTR 0
> +#define Y_AXIS_ATTR 1
> +#define Z_AXIS_ATTR 2
> +#define DATA_ATTR 3
> +
> +/*
> + * Functions declaration
> + */
> +static void adxl345_init_client(struct i2c_client *client);
> +static struct adxl345_data *adxl345_update_device(struct device *dev);
> +static void convert_to_fraction(s16 data, u8 whole_scale, u8
> fraction_scale,
> + int *decimal, int *fraction);
> +
> +/*
> + * Client data (each client gets its own)
> + */
> +struct adxl345_data {
> + struct i2c_client client;
> + struct device *hwmon_dev;
> + struct mutex update_lock; /* lock on the structure
> */
> + char valid; /* 0 until below are
> valid */
> + unsigned long last_updated; /* in jiffies */
> +
> + /*
> + * ADXL345 Data
> + * In two's complement, data coming in from or going out to
> user-space
> + * must be converted.
> + */
> + u8 offset[NUMBER_OF_AXES];
> + u16 data[NUMBER_OF_AXES];
> +};
> +
> +
> +/*
> + * Converts internal data to a decimal-fraction value.
> + * Notes: Must already be converted out of twos complement
> + *
> + * @param data Data to be converted
> + * @param whole_scale Scale factor for whole number part. (Set to 1 for
> no scaling).
> + * @param fraction_scale Scale factor for fractional number part. (Set
> to 1 for no scaling).
> + * @param decimal Pointer to location to store decimal part.
> + * @param fraction Pointer to location to store fractional part.
> + */
> +static void convert_to_fraction(s16 data, u8 whole_scale, u8
> fraction_scale,
> + int *decimal, int *fraction)
> +{
> + int temp_decimal, temp_fraction, temp;
> + int sign = 1;
> +
> + /* Scale the decimal and fractional parts */
> + temp_decimal = data * whole_scale * 10;
> + temp_fraction = data * fraction_scale;
> +
> + /* get rid of the sign for negative fractions */
> + if (temp_fraction < 0) {
> + sign = -1;
> + temp_fraction *= sign;
> + }
> +
> + /* If necessary, carry */
> + if (temp_fraction >= 10) {
> + /* Add to the decimal part */
> + temp_decimal += sign * temp_fraction;
> +
> + /* Amount to be subtracted from the fractional part */
> + temp = temp_fraction / 10;
> +
> + temp_fraction -= temp * 10;
> + }
> +
> + temp_decimal /= 10;
> +
> + /*
> + * If at least 10 still remains in the fractional part, one
> + * last carry
> + */
> + if (temp_fraction >= 10) {
> + temp_decimal += sign;
> + temp_fraction -= 10;
> + }
> +
> + /* Pass the values up */
> + *decimal = temp_decimal;
> + *fraction = temp_fraction;
> +}
> +
> +/*
> + * Called in response to cat ofs(x,y,z) in sysfs
> + *
> + * @param dev Pointer to device
> + * @param attr Pointer to the device attributes
> + * @param buf Pointer to string shown in user space
> + * @return Number of chars copied to buffer
> +*/
> +static ssize_t show_offset(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + int index = to_sensor_dev_attr(attr)->index;
> + struct adxl345_data *data = adxl345_update_device(dev);
> + int decimal, fraction;
> + s8 temp_data;
> +
> + dev_dbg(dev, "%s\n", __func__);
> +
> + /* Convert from 2's complement */
> + temp_data = ~(data->offset[index] - 1);
> +
> + dev_dbg(dev, "temp_data=%d\n", temp_data);
> +
> + convert_to_fraction(temp_data,
> + OFFSET_SCALE_FACTOR_WHOLE,
> + OFFSET_SCALE_FACTOR_FRACTIONAL,
> + &decimal,
> + &fraction);
> +
> + return snprintf(buf, PAGE_SIZE,
> + "%4d.%1d\n", decimal, fraction);
> +}
> +
> +/*
> + * Called in response to echoing data to ofs(x,y,z) in sysfs
> + * Note: Input range is -1998 to 1998 milli-g's
> + *
> + * @param dev Pointer to device
> + * @param attr Pointer to the device attributes
> + * @param buf Pointer to string passed in from user space
> + * @param count Number of chars passed in from user space..
> + * @return Number of chars passed in from user space.
> + */
> +static ssize_t set_offset(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf,
> + size_t count)
> +{
> + int index = to_sensor_dev_attr(attr)->index;
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adxl345_data *data = i2c_get_clientdata(client);
> + long val;
> + long temp_val;
> +
> + dev_dbg(dev, "%s\n", __func__);
> +
> + if (!strict_strtol(buf, 10, &val)) {
> + dev_dbg(dev, "error in converting string '%s' to
> long\n",
> + buf);
> + return 0;
> + }
> +
> + /* If outside offset range, clip to max or min value */
> + if (val < MIN_OFFSET)
> + val = MIN_OFFSET;
> + else if (val > MAX_OFFSET)
> + val = MAX_OFFSET;
> +
> + temp_val = (val * 100) %
> + ((OFFSET_SCALE_FACTOR_WHOLE * 100) +
> + (OFFSET_SCALE_FACTOR_FRACTIONAL * 10));
> + if (temp_val < 0)
> + temp_val *= -1;
> +
> + /* Get rid of scale for internal storage */
> + val = (val * 100) /
> + ((OFFSET_SCALE_FACTOR_WHOLE * 100) +
> + (OFFSET_SCALE_FACTOR_FRACTIONAL * 10));
> +
> + if (temp_val > (OFFSET_SCALE_FACTOR_WHOLE * 100) / 2 && val > 0)
> + ++val;
> + else if (temp_val > (OFFSET_SCALE_FACTOR_WHOLE * 100) / 2 && val
> < 0)
> + --val;
> +
> + val = ~val + 1; /* convert to two's complement */
> +
> + mutex_lock(&data->update_lock);
> +
> + data->offset[index] = val;
> +
> + dev_dbg(dev, "offset[%d]=%d\n", index, data->offset[index]);
> +
> + /* Write the avlue to the chip via I2C */
> + i2c_smbus_write_byte_data(client,
> + ADXL345_REG_OFS(index),
> + data->offset[index]);
> +
> + mutex_unlock(&data->update_lock);
> +
> + return count;
> +}
> +
> +/*
> + * Called in response to cat data in sysfs
> + *
> + * @param dev Pointer to device
> + * @param attr Pointer to the device attributes
> + * @param buf Pointer to string shown in user space
> + * @return Number of chars copied to buffer
> +*/
> +static ssize_t show_data(struct device *dev, struct device_attribute
> *attr,
> + char *buf)
> +{
> + int i;
> + s16 temp_data;
> + int decimal[NUMBER_OF_AXES], fraction[NUMBER_OF_AXES];
> +
> + struct adxl345_data *data = adxl345_update_device(dev);
> +
> + /* Convert x,y,z values */
> + for (i = 0; i < NUMBER_OF_AXES; i++) {
> + /* Convert from 2's complement */
> + temp_data = ~(data->data[i] - 1);
> +
it doesn't need convertion if data->data[i] with bit16==0.
--wxc200
> + convert_to_fraction(temp_data,
> + DATA_SCALE_FACTOR_WHOLE,
> + DATA_SCALE_FACTOR_FRACTIONAL,
> + &decimal[i],
> + &fraction[i]);
> + }
> +
> + return snprintf(buf, PAGE_SIZE,
> + "x:%5d.%1d y:%5d.%1d z:%5d.%1d\n",
> + decimal[X_AXIS], fraction[X_AXIS],
> + decimal[Y_AXIS], fraction[Y_AXIS],
> + decimal[Z_AXIS], fraction[Z_AXIS]);
> +}
> +
> +/* Attributes of the sysfs entries */
> +static SENSOR_DEVICE_ATTR(ofsx, S_IWUSR | S_IRUGO,
> + show_offset, set_offset, X_AXIS_ATTR);
> +static SENSOR_DEVICE_ATTR(ofsy, S_IWUSR | S_IRUGO,
> + show_offset, set_offset, Y_AXIS_ATTR);
> +static SENSOR_DEVICE_ATTR(ofsz, S_IWUSR | S_IRUGO,
> + show_offset, set_offset, Z_AXIS_ATTR);
> +static SENSOR_DEVICE_ATTR(data, S_IRUGO,
> + show_data, NULL, DATA_ATTR);
> +
> +static struct attribute *adxl345_attributes[] = {
> + &sensor_dev_attr_ofsx.dev_attr.attr,
> + &sensor_dev_attr_ofsy.dev_attr.attr,
> + &sensor_dev_attr_ofsz.dev_attr.attr,
> + &sensor_dev_attr_data.dev_attr.attr,
> + NULL
> +};
> +
> +static const struct attribute_group adxl345_group = {
> + .attrs = adxl345_attributes,
> +};
> +
> +/*
> + * Initialize the chip
> + *
> + * @param client Pointer to the client structure
> + */
> +static void adxl345_init_client(struct i2c_client *client)
> +{
> + dev_dbg(&client->dev, "%s\n", __func__);
> +
> + /*
> + * Set up the device, No self test, Dont care about SPI or
> + * interrupt, 10 bit resoltion, +/- 16g range
> + */
> + i2c_smbus_write_byte_data(client, ADXL345_REG_DATA_FORMAT,
> 0x03);
> +}
> +
> +/*
> + * Does more than just detection. If detection succeeds, it also
> + * registers the new chip.
> + *
> + * @param adapter Pointer to the adapter
> + * @param address I2C address
> + * @return Zero, upon success
> + */
> +static int adxl345_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct adxl345_data *data;
> + int err = 0;
> + u8 dev_id;
> +
> + dev_dbg(&client->dev, "%s\n", __func__);
> +
> + if (!i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_BYTE_DATA))
> + return -ENODEV;
> +
> + data = kzalloc(sizeof(struct adxl345_data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + i2c_set_clientdata(client, data);
> +
> + #ifdef SIMULATE
> + dev_id = 0xE5; /* Spoof the Analog Devices device ID */
> + dev_dbg(&client->dev, "Simulating ADXL345 device\n");
> + #else
> + dev_id = i2c_smbus_read_byte_data(client, ADXL345_REG_DEV_ID);
> + #endif
> +
> + /* If the chip is not from Analog Devices, report an error */
> + if (dev_id != 0xE5) {
> + dev_err(&client->dev, "Unsupported chip
> (dev_id=0x%02X)\n",
> + dev_id);
> + err = -EINVAL;
> + goto err_free_mem;
> + }
> +
> + dev_info(&client->dev, "chip found, driver version "
> + DRV_VERSION "\n");
> +
> + /* We can fill in the remaining client fields */
> + mutex_init(&data->update_lock);
> +
> + /* Initialize the ADXL345 chip */
> + adxl345_init_client(client);
> +
> + /* Register sysfs hooks */
> + err = sysfs_create_group(&client->dev.kobj, &adxl345_group);
> + if (err)
> + goto err_free_mem;
> +
> + data->hwmon_dev = hwmon_device_register(&client->dev);
> + if (IS_ERR(data->hwmon_dev)) {
> + err = PTR_ERR(data->hwmon_dev);
> + goto err_remove;
> + }
> +
> + return 0;
> +
> +err_remove:
> + sysfs_remove_group(&client->dev.kobj, &adxl345_group);
> +err_free_mem:
> + kfree(data);
> +
> + return err;
> +}
> +
> +/*
> + * Unregister device, remove the sysfs entries, and detach the client
> + * from I2C bus.
> + *
> + * @param client Pointer to the client structure
> + * @return Zero, upon success.
> + */
> +static int adxl345_remove(struct i2c_client *client)
> +{
> + struct adxl345_data *data = i2c_get_clientdata(client);
> +
> + hwmon_device_unregister(data->hwmon_dev);
> + sysfs_remove_group(&client->dev.kobj, &adxl345_group);
> +
> + i2c_unregister_device(client);
> +
> + kfree(data);
> +
> + return 0;
> +}
> +
> +/*
> + * Gets the data from the chip.
> + *
> + * @param client Pointer to the device
> + * @return Pointer to structure containing the data
> + */
> +static struct adxl345_data *adxl345_update_device(struct device *dev)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adxl345_data *data = i2c_get_clientdata(client);
> + int i;
> +
> + dev_dbg(dev, "%s\n", __func__);
> +
> + mutex_lock(&data->update_lock);
> +
> + /*
> + * This delay is 500ms, based on a default value of 100 for HZ
> + * in ARM kernels
> + */
> + if (time_after(jiffies, data->last_updated + HZ * 50) ||
> + !data->valid) {
> + for (i = 0; i < NUMBER_OF_AXES; i++) {
> + data->offset[i] =
> i2c_smbus_read_byte_data(client,
> + ADXL345_REG_OFS(i));
> + dev_dbg(dev, "offset[%d]=%d\n", i,
> data->offset[i]);
> + }
> +
> + /*
> + * Concatenate the data from each register pair
> + * Indexing logic is needed as per ADXL345 spec, LSB is
> first
> + * INDEX(reg) LSB MSB
> + * 0 0 1
> + * 1 2 3
> + * 2 4 5
> + */
> + for (i = 0; i < NUMBER_OF_AXES; i++) {
> + /* Get the MSB, shift by 8, and then get the LSB
> */
> + data->data[i] = i2c_smbus_read_byte_data(client,
> + ADXL345_REG_DATA(i*2+1))
> << 8;
> + data->data[i] |=
> i2c_smbus_read_byte_data(client,
> + ADXL345_REG_DATA(i*2));
> +
> + dev_dbg(dev, "data[%d]=%d\n", i, data->data[i]);
> + }
> +
> + data->last_updated = jiffies;
> + data->valid = 1;
> + }
> +
> + mutex_unlock(&data->update_lock);
> +
> + return data;
> +}
> +
> +/*
> + * Driver data (common to all clients)
> + */
> +
> +static const struct i2c_device_id adxl345_id[] = {
> + { "adxl345", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, adxl345_id);
> +
> +static struct i2c_driver adxl345_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + },
> + .probe = adxl345_probe,
> + .remove = adxl345_remove,
> + .id_table = adxl345_id,
> +};
> +
> +/*
> + * Initialize the module
> + *
> + * @return Zero, upon success
> + */
> +static int __init adxl345_init(void)
> +{
> + return i2c_add_driver(&adxl345_driver);
> +}
> +
> +/*
> + * Remove the module
> + */
> +static void __exit adxl345_exit(void)
> +{
> + i2c_del_driver(&adxl345_driver);
> +}
> +
> +MODULE_AUTHOR("Robert Mehranfar <robertme@...thlink.net>");
> +MODULE_DESCRIPTION("Analog Devices ADXL345 driver");
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(DRV_VERSION);
> +
> +module_init(adxl345_init);
> +module_exit(adxl345_exit);
--
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