Ambient light sensor that supports visible light and IR measurements and configurable gain/integration time.
This is written as an additional driver instead of being added into the existing bh1750 / bh1780 drivers. The bh1730 chip is significantly different from either of these two: * bh1750 is not fully smbus compatible and only partially supports continuous reading mode since not all of its supported chips have this feature. * bh1780 does gain adjustment in hardware and exposes lux values directly, as opposed to bh1730 which provides two raw channels (IR + visible light) and requires manual gain adjustment and lux computation in the driver. Changed in v2: * Split off DT documentation change into a separate commit. * Use i2c's probe_new. Changed in v3: * Moved from 64 bit to 32 bit arithmetic where possible. * Changed IIO channel configuration for consistency with other drivers. * Refactored mathematical computations for readability. * Removed unnecessary CONFIG_OF checks. Signed-off-by: Pierre Bourdon <[email protected]> --- drivers/iio/light/Kconfig | 10 + drivers/iio/light/Makefile | 1 + drivers/iio/light/bh1730.c | 434 +++++++++++++++++++++++++++++++++++++ 3 files changed, 445 insertions(+) create mode 100644 drivers/iio/light/bh1730.c diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig index 93fd421b10d7..286a7f78762b 100644 --- a/drivers/iio/light/Kconfig +++ b/drivers/iio/light/Kconfig @@ -63,6 +63,16 @@ config APDS9960 To compile this driver as a module, choose M here: the module will be called apds9960 +config BH1730 + tristate "ROHM BH1730 ambient light sensor" + depends on I2C + help + Say Y here to build support for the ROHM BH1730FVC ambient + light sensor. + + To compile this driver as a module, choose M here: the module will + be called bh1730. + config BH1750 tristate "ROHM BH1750 ambient light sensor" depends on I2C diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile index f714067a7816..eb9010a10536 100644 --- a/drivers/iio/light/Makefile +++ b/drivers/iio/light/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_ADJD_S311) += adjd_s311.o obj-$(CONFIG_AL3320A) += al3320a.o obj-$(CONFIG_APDS9300) += apds9300.o obj-$(CONFIG_APDS9960) += apds9960.o +obj-$(CONFIG_BH1730) += bh1730.o obj-$(CONFIG_BH1750) += bh1750.o obj-$(CONFIG_BH1780) += bh1780.o obj-$(CONFIG_CM32181) += cm32181.o diff --git a/drivers/iio/light/bh1730.c b/drivers/iio/light/bh1730.c new file mode 100644 index 000000000000..4a23fbd6ff84 --- /dev/null +++ b/drivers/iio/light/bh1730.c @@ -0,0 +1,434 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * ROHM BH1730 ambient light sensor driver + * + * Copyright (c) 2018 Google, Inc. + * Author: Pierre Bourdon <[email protected]> + * + * Based on a previous non-iio BH1730FVC driver: + * Copyright (C) 2012 Samsung Electronics. All rights reserved. + * Author: Won Huh <[email protected]> + * + * Data sheets: + * http://www.rohm.com/web/global/datasheet/BH1730FVC/bh1730fvc-e + */ + +#include <linux/delay.h> +#include <linux/i2c.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/time.h> + +#define BH1730_CMD_BIT BIT(7) + +#define BH1730_REG_CONTROL 0x00 +#define BH1730_REG_TIMING 0x01 +#define BH1730_REG_INTERRUPT 0x02 +#define BH1730_REG_THLLOW 0x03 +#define BH1730_REG_THLHIGH 0x04 +#define BH1730_REG_THHLOW 0x05 +#define BH1730_REG_THHHIGH 0x06 +#define BH1730_REG_GAIN 0x07 +#define BH1730_REG_ID 0x12 +#define BH1730_REG_DATA0LOW 0x14 +#define BH1730_REG_DATA0HIGH 0x15 +#define BH1730_REG_DATA1LOW 0x16 +#define BH1730_REG_DATA1HIGH 0x17 + +#define BH1730_CONTROL_POWER_ON BIT(0) +#define BH1730_CONTROL_MEASURE BIT(1) + +#define BH1730_INTERNAL_CLOCK_NS 2800 + +#define BH1730_DEFAULT_INTEG_MS 150 + +enum bh1730_gain { + BH1730_GAIN_1X = 0, + BH1730_GAIN_2X, + BH1730_GAIN_64X, + BH1730_GAIN_128X, +}; +#define BH1730_MAX_GAIN_MULTIPLIER 128 + +struct bh1730_data { + struct i2c_client *client; + enum bh1730_gain gain; + int itime; +}; +#define BH1730_MAX_GAIN_MULTIPLIER 128 + +static int bh1730_read_word(struct bh1730_data *bh1730, u8 reg) +{ + int ret = i2c_smbus_read_word_data(bh1730->client, + BH1730_CMD_BIT | reg); + if (ret < 0) + dev_err(&bh1730->client->dev, + "i2c read failed error %d, register %01x\n", + ret, reg); + + return ret; +} + +static int bh1730_write(struct bh1730_data *bh1730, u8 reg, u8 val) +{ + int ret = i2c_smbus_write_byte_data(bh1730->client, + BH1730_CMD_BIT | reg, + val); + if (ret < 0) + dev_err(&bh1730->client->dev, + "i2c write failed error %d, register %01x\n", + ret, reg); + + return ret; +} + +static int gain_setting_to_multiplier(enum bh1730_gain gain) +{ + switch (gain) { + case BH1730_GAIN_1X: + return 1; + case BH1730_GAIN_2X: + return 2; + case BH1730_GAIN_64X: + return 64; + case BH1730_GAIN_128X: + return 128; + default: + return -EINVAL; + } +} + +static int bh1730_gain_multiplier(struct bh1730_data *bh1730) +{ + int multiplier = gain_setting_to_multiplier(bh1730->gain); + + if (multiplier < 0) { + dev_warn(&bh1730->client->dev, + "invalid gain multiplier settings: %d\n", + bh1730->gain); + bh1730->gain = BH1730_GAIN_1X; + multiplier = 1; + } + + return multiplier; +} + +static int bh1730_itime_us(struct bh1730_data *bh1730) +{ + return (BH1730_INTERNAL_CLOCK_NS * 964 * (256 - bh1730->itime)) + / NSEC_PER_USEC; +} + +static int bh1730_set_gain(struct bh1730_data *bh1730, enum bh1730_gain gain) +{ + int ret = bh1730_write(bh1730, BH1730_REG_GAIN, gain); + + if (ret < 0) + return ret; + + bh1730->gain = gain; + + return 0; +} + +static int bh1730_set_integration_time_ms(struct bh1730_data *bh1730, + int time_ms) +{ + int ret, time_ns, itime; + + /* Prefilter obviously invalid time_ms values that would overflow. */ + if (time_ms <= 0 || time_ms > 1000) + goto out_of_range; + + time_ns = time_ms * NSEC_PER_MSEC; + itime = 256 - DIV_ROUND_CLOSEST(time_ns, + BH1730_INTERNAL_CLOCK_NS * 964); + + /* ITIME == 0 is reserved for manual integration mode. */ + if (itime <= 0 || itime > 255) + goto out_of_range; + + ret = bh1730_write(bh1730, BH1730_REG_TIMING, itime); + if (ret < 0) + return ret; + + bh1730->itime = itime; + + return 0; + +out_of_range: + dev_warn(&bh1730->client->dev, "integration time out of range: %dms\n", + time_ms); + + return -ERANGE; +} + +static void bh1730_wait_for_next_measurement(struct bh1730_data *bh1730) +{ + udelay(bh1730_itime_us(bh1730) + + DIV_ROUND_UP(BH1730_INTERNAL_CLOCK_NS * 714, NSEC_PER_USEC)); +} + +static int bh1730_adjust_gain(struct bh1730_data *bh1730) +{ + int visible, ir, highest, gain, ret, i; + + visible = bh1730_read_word(bh1730, BH1730_REG_DATA0LOW); + if (visible < 0) + return visible; + + ir = bh1730_read_word(bh1730, BH1730_REG_DATA1LOW); + if (ir < 0) + return ir; + + highest = max(visible, ir); + + /* + * If the read value is being clamped, assume the worst and go to the + * lowest possible gain. The alternative is doing multiple + * recalibrations, which would be slower and have the same effect. + */ + if (highest == USHRT_MAX) + gain = 1; + else + gain = bh1730_gain_multiplier(bh1730); + + highest = (highest * BH1730_MAX_GAIN_MULTIPLIER) / gain; + + /* + * Find the lowest gain multiplier which puts the measured values + * above 1024. This threshold is chosen to match the gap between 2X + * multiplier and 64X (next available) while keeping some margin. + */ + for (i = BH1730_GAIN_1X; i < BH1730_GAIN_128X; ++i) { + int adj = highest * gain_setting_to_multiplier(i) / + BH1730_MAX_GAIN_MULTIPLIER; + + if (adj >= 1024) + break; + } + + if (i != bh1730->gain) { + ret = bh1730_set_gain(bh1730, i); + if (ret < 0) + return ret; + + bh1730_wait_for_next_measurement(bh1730); + } + + return 0; +} + +static int bh1730_get_millilux(struct bh1730_data *bh1730) +{ + int visible, ir, visible_coef, ir_coef; + u64 millilux; + + visible = bh1730_read_word(bh1730, BH1730_REG_DATA0LOW); + if (visible < 0) + return visible; + + ir = bh1730_read_word(bh1730, BH1730_REG_DATA1LOW); + if (ir < 0) + return ir; + + if (ir * 1000 / visible < 500) { + visible_coef = 5002; + ir_coef = 7502; + } else if (ir * 1000 / visible < 754) { + visible_coef = 2250; + ir_coef = 2000; + } else if (ir * 1000 / visible < 1029) { + visible_coef = 1999; + ir_coef = 1667; + } else if (ir * 1000 / visible < 1373) { + visible_coef = 885; + ir_coef = 583; + } else if (ir * 1000 / visible < 1879) { + visible_coef = 309; + ir_coef = 165; + } else { + return 0; + } + + millilux = 103ULL * (visible_coef * visible - ir_coef * ir); + millilux *= USEC_PER_MSEC; + do_div(millilux, bh1730_itime_us(bh1730)); + do_div(millilux, bh1730_gain_multiplier(bh1730)); + + /* + * Overflow here can only happen in extreme conditions: + * - Completely saturated visible light sensor and no measured IR. + * - Integration time < 16ms (driver currently defaults to 150ms). + */ + if (millilux > INT_MAX) + return -ERANGE; + + return (int)millilux; +} + +static int bh1730_power_on(struct bh1730_data *bh1730) +{ + return bh1730_write(bh1730, BH1730_REG_CONTROL, + BH1730_CONTROL_POWER_ON | BH1730_CONTROL_MEASURE); +} + +static int bh1730_set_defaults(struct bh1730_data *bh1730) +{ + int ret; + + ret = bh1730_set_gain(bh1730, BH1730_GAIN_1X); + if (ret < 0) + return ret; + + ret = bh1730_set_integration_time_ms(bh1730, BH1730_DEFAULT_INTEG_MS); + if (ret < 0) + return ret; + + bh1730_wait_for_next_measurement(bh1730); + + return 0; +} + +static int bh1730_power_off(struct bh1730_data *bh1730) +{ + return bh1730_write(bh1730, BH1730_REG_CONTROL, 0); +} + +static int bh1730_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct bh1730_data *bh1730 = iio_priv(indio_dev); + int data_reg, ret; + + ret = bh1730_adjust_gain(bh1730); + if (ret < 0) + return ret; + + switch (mask) { + case IIO_CHAN_INFO_PROCESSED: + ret = bh1730_get_millilux(bh1730); + if (ret < 0) + return ret; + *val = ret / 1000; + *val2 = (ret % 1000) * 1000; + return IIO_VAL_INT_PLUS_MICRO; + case IIO_CHAN_INFO_RAW: + switch (chan->channel2) { + case IIO_MOD_LIGHT_CLEAR: + data_reg = BH1730_REG_DATA0LOW; + break; + case IIO_MOD_LIGHT_IR: + data_reg = BH1730_REG_DATA1LOW; + break; + default: + return -EINVAL; + } + ret = bh1730_read_word(bh1730, data_reg); + if (ret < 0) + return ret; + ret = ret * 1000 / bh1730_gain_multiplier(bh1730); + *val = ret / 1000; + *val2 = (ret % 1000) * 1000; + return IIO_VAL_INT_PLUS_MICRO; + default: + return -EINVAL; + } +} + +static const struct iio_info bh1730_info = { + .read_raw = bh1730_read_raw, +}; + +static const struct iio_chan_spec bh1730_channels[] = { + { + .type = IIO_LIGHT, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), + }, + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_CLEAR, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + }, + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_IR, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + }, +}; + +static int bh1730_probe(struct i2c_client *client) +{ + struct bh1730_data *bh1730; + struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent); + struct iio_dev *indio_dev; + int ret; + + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE)) + return -EIO; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*bh1730)); + if (!indio_dev) + return -ENOMEM; + + bh1730 = iio_priv(indio_dev); + bh1730->client = client; + i2c_set_clientdata(client, indio_dev); + + ret = bh1730_power_on(bh1730); + if (ret < 0) + return ret; + + ret = bh1730_set_defaults(bh1730); + if (ret < 0) + return ret; + + indio_dev->dev.parent = &client->dev; + indio_dev->info = &bh1730_info; + indio_dev->name = "bh1730"; + indio_dev->channels = bh1730_channels; + indio_dev->num_channels = ARRAY_SIZE(bh1730_channels); + indio_dev->modes = INDIO_DIRECT_MODE; + + ret = iio_device_register(indio_dev); + if (ret) + goto out_power_off; + return 0; + +out_power_off: + bh1730_power_off(bh1730); + return ret; +} + +static int bh1730_remove(struct i2c_client *client) +{ + struct iio_dev *indio_dev = i2c_get_clientdata(client); + struct bh1730_data *bh1730 = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + return bh1730_power_off(bh1730); +} + +static const struct of_device_id of_bh1730_match[] = { + { .compatible = "rohm,bh1730fvc" }, + {}, +}; +MODULE_DEVICE_TABLE(of, of_bh1730_match); + +static struct i2c_driver bh1730_driver = { + .probe_new = bh1730_probe, + .remove = bh1730_remove, + .driver = { + .name = "bh1730", + .of_match_table = of_bh1730_match, + }, +}; +module_i2c_driver(bh1730_driver); + +MODULE_AUTHOR("Pierre Bourdon <[email protected]>"); +MODULE_DESCRIPTION("ROHM BH1730FVC driver"); +MODULE_LICENSE("GPL v2"); -- 2.16.2.395.g2e18187dfd-goog
