path: root/drivers/iio/light/apds9306.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * APDS-9306/APDS-9306-065 Ambient Light Sensor
 * I2C Address: 0x52
 * Datasheet: https://docs.broadcom.com/doc/AV02-4755EN
 *
 * Copyright (C) 2024 Subhajit Ghosh <subhajit.ghosh@tweaklogic.com>
 */

#include <linux/bits.h>
#include <linux/cleanup.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/types.h>
#include <linux/units.h>

#include <linux/iio/iio.h>
#include <linux/iio/iio-gts-helper.h>
#include <linux/iio/events.h>
#include <linux/iio/sysfs.h>

#include <linux/unaligned.h>

#define APDS9306_MAIN_CTRL_REG		0x00
#define APDS9306_ALS_MEAS_RATE_REG	0x04
#define APDS9306_ALS_GAIN_REG		0x05
#define APDS9306_PART_ID_REG		0x06
#define APDS9306_MAIN_STATUS_REG	0x07
#define APDS9306_CLEAR_DATA_0_REG	0x0A
#define APDS9306_CLEAR_DATA_1_REG	0x0B
#define APDS9306_CLEAR_DATA_2_REG	0x0C
#define APDS9306_ALS_DATA_0_REG		0x0D
#define APDS9306_ALS_DATA_1_REG		0x0E
#define APDS9306_ALS_DATA_2_REG		0x0F
#define APDS9306_INT_CFG_REG		0x19
#define APDS9306_INT_PERSISTENCE_REG	0x1A
#define APDS9306_ALS_THRES_UP_0_REG	0x21
#define APDS9306_ALS_THRES_UP_1_REG	0x22
#define APDS9306_ALS_THRES_UP_2_REG	0x23
#define APDS9306_ALS_THRES_LOW_0_REG	0x24
#define APDS9306_ALS_THRES_LOW_1_REG	0x25
#define APDS9306_ALS_THRES_LOW_2_REG	0x26
#define APDS9306_ALS_THRES_VAR_REG	0x27

#define APDS9306_ALS_INT_STAT_MASK	BIT(4)
#define APDS9306_ALS_DATA_STAT_MASK	BIT(3)

#define APDS9306_ALS_THRES_VAL_MAX	(BIT(20) - 1)
#define APDS9306_ALS_THRES_VAR_NUM_VALS	8
#define APDS9306_ALS_PERSIST_NUM_VALS	16
#define APDS9306_ALS_READ_DATA_DELAY_US	(20 * USEC_PER_MSEC)
#define APDS9306_NUM_REPEAT_RATES	7
#define APDS9306_INT_SRC_CLEAR	0
#define APDS9306_INT_SRC_ALS	1
#define APDS9306_SAMP_FREQ_10HZ	0

/**
 * struct part_id_gts_multiplier - Part no. and corresponding gts multiplier
 *
 * GTS (Gain Time Scale) are helper functions for Light sensors which along
 * with hardware gains also has gains associated with Integration times.
 *
 * There are two variants of the device with slightly different characteristics,
 * they have same ADC count for different Lux levels as mentioned in the
 * datasheet. This multiplier array is used to store the derived Lux per count
 * value for the two variants to be used by the GTS helper functions.
 *
 * @part_id: Part ID of the device
 * @max_scale_int: Multiplier for iio_init_iio_gts()
 * @max_scale_nano: Multiplier for iio_init_iio_gts()
 */
struct part_id_gts_multiplier {
	int part_id;
	int max_scale_int;
	int max_scale_nano;
};

/*
 * As per the datasheet, at HW Gain = 3x, Integration time 100mS (32x),
 * typical 2000 ADC counts are observed for 49.8 uW per sq cm (340.134 lux)
 * for apds9306 and 43 uW per sq cm (293.69 lux) for apds9306-065.
 * Assuming lux per count is linear across all integration time ranges.
 *
 * Lux = (raw + offset) * scale; offset can be any value by userspace.
 * HG = Hardware Gain; ITG = Gain by changing integration time.
 * Scale table by IIO GTS Helpers = (1 / HG) * (1 / ITG) * Multiplier.
 *
 * The Lux values provided in the datasheet are at ITG=32x and HG=3x,
 * at typical 2000 count for both variants of the device.
 *
 * Lux per ADC count at 3x and 32x for apds9306 = 340.134 / 2000
 * Lux per ADC count at 3x and 32x for apds9306-065 = 293.69 / 2000
 *
 * The Multiplier for the scale table provided to userspace:
 * IIO GTS scale Multiplier for apds9306 = (340.134 / 2000) * 32 * 3 = 16.326432
 * and for apds9306-065 = (293.69 / 2000) * 32 * 3 = 14.09712
 */
static const struct part_id_gts_multiplier apds9306_gts_mul[] = {
	{
		.part_id = 0xB1,
		.max_scale_int = 16,
		.max_scale_nano = 3264320,
	}, {
		.part_id = 0xB3,
		.max_scale_int = 14,
		.max_scale_nano = 9712000,
	},
};

static const int apds9306_repeat_rate_freq[APDS9306_NUM_REPEAT_RATES][2] = {
	{ 40, 0 },
	{ 20, 0 },
	{ 10, 0 },
	{ 5,  0 },
	{ 2,  0 },
	{ 1,  0 },
	{</