linux-imx

/*

 * apds9300.c - IIO driver for Avago APDS9300 ambient light sensor

 *

 * Copyright 2013 Oleksandr Kravchenko <o.v.kravchenko@globallogic.com>

 *

 * This file is subject to the terms and conditions of version 2 of

 * the GNU General Public License.  See the file COPYING in the main

 * directory of this archive for more details.

 */

​

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/pm.h>

#include <linux/i2c.h>

#include <linux/err.h>

#include <linux/mutex.h>

#include <linux/interrupt.h>

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>

#include <linux/iio/events.h>

​

#define APDS9300_DRV_NAME "apds9300"

#define APDS9300_IRQ_NAME "apds9300_event"

​

/* Command register bits */

#define APDS9300_CMD    BIT(7) /* Select command register. Must write as 1 */

#define APDS9300_WORD   BIT(5) /* I2C write/read: if 1 word, if 0 byte */

#define APDS9300_CLEAR  BIT(6) /* Interrupt clear. Clears pending interrupt */

​

/* Register set */

#define APDS9300_CONTROL    0x00 /* Control of basic functions */

#define APDS9300_THRESHLOWLOW   0x02 /* Low byte of low interrupt threshold */

#define APDS9300_THRESHHIGHLOW  0x04 /* Low byte of high interrupt threshold */

#define APDS9300_INTERRUPT  0x06 /* Interrupt control */

#define APDS9300_DATA0LOW   0x0c /* Low byte of ADC channel 0 */

#define APDS9300_DATA1LOW   0x0e /* Low byte of ADC channel 1 */

​

/* Power on/off value for APDS9300_CONTROL register */

#define APDS9300_POWER_ON   0x03

#define APDS9300_POWER_OFF  0x00

​

/* Interrupts */

#define APDS9300_INTR_ENABLE    0x10

/* Interrupt Persist Function: Any value outside of threshold range */

#define APDS9300_THRESH_INTR    0x01

​

#define APDS9300_THRESH_MAX 0xffff /* Max threshold value */

​

struct apds9300_data {

    struct i2c_client *client;

    struct mutex mutex;

    int power_state;

    int thresh_low;

    int thresh_hi;

    int intr_en;

};

​

/* Lux calculation */

​

/* Calculated values 1000 * (CH1/CH0)^1.4 for CH1/CH0 from 0 to 0.52 */

static const u16 apds9300_lux_ratio[] = {

    0, 2, 4, 7, 11, 15, 19, 24, 29, 34, 40, 45, 51, 57, 64, 70, 77, 84, 91,

    98, 105, 112, 120, 128, 136, 144, 152, 160, 168, 177, 185, 194, 203,

    212, 221, 230, 239, 249, 258, 268, 277, 287, 297, 307, 317, 327, 337,

    347, 358, 368, 379, 390, 400,

};

​

static unsigned long apds9300_calculate_lux(u16 ch0, u16 ch1)

{

    unsigned long lux, tmp;

​

    /* avoid division by zero */

    if (ch0 == 0)

        return 0;

​

    tmp = DIV_ROUND_UP(ch1 * 100, ch0);

    if (tmp <= 52) {

        lux = 3150 * ch0 - (unsigned long)DIV_ROUND_UP_ULL(ch0

                * apds9300_lux_ratio[tmp] * 5930ull, 1000);

    } else if (tmp <= 65) {

        lux = 2290 * ch0 - 2910 * ch1;

    } else if (tmp <= 80) {

        lux = 1570 * ch0 - 1800 * ch1;

    } else if (tmp <= 130) {

        lux = 338 * ch0 - 260 * ch1;

    } else {

        lux = 0;

    }

​

    return lux / 100000;

}

​