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/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Intersil ILS29035 light sensor driver
*/
#include "driver/als_isl29035.h"
#include "i2c.h"
/* I2C interface */
#define ILS29035_I2C_ADDR 0x88
#define ILS29035_REG_COMMAND_I 0
#define ILS29035_REG_COMMAND_II 1
#define ILS29035_REG_DATA_LSB 2
#define ILS29035_REG_DATA_MSB 3
#define ILS29035_REG_INT_LT_LSB 4
#define ILS29035_REG_INT_LT_MSB 5
#define ILS29035_REG_INT_HT_LSB 6
#define ILS29035_REG_INT_HT_MSB 7
#define ILS29035_REG_ID 15
int isl29035_init(void)
{
/*
* Tell it to read continually. This uses 70uA, as opposed to nearly
* zero, but it makes the hook/update code cleaner (we don't want to
* wait 90ms to read on demand while processing hook callbacks).
*/
return i2c_write8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
ILS29035_REG_COMMAND_I, 0xa0);
}
int isl29035_read_lux(int *lux, int af)
{
int rv, lsb, msb, data;
/*
* NOTE: It is necessary to read the LSB first, then the MSB. If you do
* it in the opposite order, the results are not correct. This is
* apparently an undocumented "feature". It's especially noticeable in
* one-shot mode.
*/
/* Read lsb */
rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
ILS29035_REG_DATA_LSB, &lsb);
if (rv)
return rv;
/* Read msb */
rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
ILS29035_REG_DATA_MSB, &msb);
if (rv)
return rv;
data = (msb << 8) | lsb;
/*
* The default power-on values will give 16 bits of precision:
* 0x0000-0xffff indicates 0-1000 lux. We multiply the sensor value by
* a scaling factor to account for attentuation by glass, tinting, etc.
*
* Caution: Don't go nuts with the attentuation factor. If it's
* greater than 32, the signed int math will roll over and you'll get
* very wrong results. Of course, if you have that much attenuation and
* are still getting useful readings, you probably have your sensor
* pointed directly into the sun.
*/
*lux = data * af * 1000 / 0xffff;
return EC_SUCCESS;
}
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