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1d2845d2db
This adds space for up to two ALS lux readings to be available to the AP
through the memory-mapped LPC region. If enabled, the values are updated
once a second.
The ALS will be reinitialized at every AP resume, since it's typically
unpowered otherwise. The reported value will be zero when the ALS is off.
BUG=chrome-os-partner:23380
BRANCH=samus
TEST=manual
Boot the AP, then from the EC console run "als" or just monitor the
memory-mapped region directly ("rw 0x40080780" on Samus), while pointing the
sensor at bright and dim areas. The value should change.
Change-Id: I705371fcd57345dc9adae1231ea30c7ff024aaf8
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/176142
Reviewed-by: Randall Spangler <rspangler@chromium.org>
73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Intersil ILS29035 light sensor driver
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*/
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#include "driver/als_isl29035.h"
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#include "common.h"
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#include "hooks.h"
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#include "i2c.h"
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#include "timer.h"
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/* I2C interface */
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#define ILS29035_I2C_ADDR 0x88
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#define ILS29035_REG_COMMAND_I 0
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#define ILS29035_REG_COMMAND_II 1
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#define ILS29035_REG_DATA_LSB 2
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#define ILS29035_REG_DATA_MSB 3
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#define ILS29035_REG_INT_LT_LSB 4
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#define ILS29035_REG_INT_LT_MSB 5
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#define ILS29035_REG_INT_HT_LSB 6
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#define ILS29035_REG_INT_HT_MSB 7
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#define ILS29035_REG_ID 15
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static void isl29035_init(void)
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{
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/*
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* Tell it to read continually. This uses 70uA, as opposed to nearly
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* zero, but it makes the hook/update code cleaner (we don't want to
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* wait 90ms to read on demand while processing hook callbacks).
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*/
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(void)i2c_write8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
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ILS29035_REG_COMMAND_I, 0xa0);
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}
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DECLARE_HOOK(HOOK_CHIPSET_RESUME, isl29035_init, HOOK_PRIO_DEFAULT);
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int isl29035_read_lux(int *lux)
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{
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int rv, lsb, msb, data;
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/*
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* NOTE: It is necessary to read the LSB first, then the MSB. If you do
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* it in the opposite order, the results are not correct. This is
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* apparently an undocumented "feature". It's especially noticeable in
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* one-shot mode.
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*/
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/* Read lsb */
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rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
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ILS29035_REG_DATA_LSB, &lsb);
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if (rv)
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return rv;
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/* Read msb */
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rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
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ILS29035_REG_DATA_MSB, &msb);
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if (rv)
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return rv;
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data = (msb << 8) | lsb;
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/*
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* The default power-on values will give 16 bits of precision:
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* 0x0000-0xffff indicates 0-1000 lux. If you change the defaults,
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* you'll need to change the scale factor accordingly (and maybe this
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* expression, to avoid rounding errors).
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*/
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*lux = data * 1000 / 0xffff;
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return EC_SUCCESS;
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}
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