[PATCH v2 1/2] iio: light: add driver for bh1730fvc chips
From: Pierre Bourdon
Date: Wed Feb 21 2018 - 14:45:58 EST
Ambient light sensor that supports visible light and IR measurements and
configurable gain/integration time.
Changed in v2:
* Split off DT documentation change into a separate commit.
* Use i2c's probe_new.
Signed-off-by: Pierre Bourdon <delroth@xxxxxxxxxx>
---
drivers/iio/light/Kconfig | 10 +
drivers/iio/light/Makefile | 1 +
drivers/iio/light/bh1730.c | 414 +++++++++++++++++++++++++++++++++++++
3 files changed, 425 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..7f1c50b3c55b
--- /dev/null
+++ b/drivers/iio/light/bh1730.c
@@ -0,0 +1,414 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ROHM BH1730 ambient light sensor driver
+ *
+ * Copyright (c) 2018 Google, Inc.
+ * Author: Pierre Bourdon <delroth@xxxxxxxxxx>
+ *
+ * Based on a previous non-iio BH1730FVC driver:
+ * Copyright (C) 2012 Samsung Electronics. All rights reserved.
+ * Author: Won Huh <won.huh@xxxxxxxxxxx>
+ *
+ * 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 2800ULL
+
+#define BH1730_DEFAULT_INTEG_MS 150
+
+enum bh1730_gain {
+ BH1730_GAIN_1X = 0,
+ BH1730_GAIN_2X,
+ BH1730_GAIN_64X,
+ BH1730_GAIN_128X,
+};
+
+struct bh1730_data {
+ struct i2c_client *client;
+ enum bh1730_gain gain;
+ int itime;
+};
+
+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 -1;
+ }
+}
+
+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 u64 bh1730_itime_ns(struct bh1730_data *bh1730)
+{
+ return BH1730_INTERNAL_CLOCK_NS * 964 * (256 - bh1730->itime);
+}
+
+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;
+ u64 time_ns = time_ms * (u64)NSEC_PER_MSEC;
+ u64 itime_step_ns = BH1730_INTERNAL_CLOCK_NS * 964;
+ int itime = 256 - (int)DIV_ROUND_CLOSEST_ULL(time_ns, itime_step_ns);
+
+ /* ITIME == 0 is reserved for manual integration mode. */
+ if (itime <= 0 || itime > 255) {
+ dev_warn(&bh1730->client->dev,
+ "integration time out of range: %dms\n", time_ms);
+ return -ERANGE;
+ }
+
+ ret = bh1730_write(bh1730, BH1730_REG_TIMING, itime);
+ if (ret < 0)
+ return ret;
+
+ bh1730->itime = itime;
+ return 0;
+}
+
+static void bh1730_wait_for_next_measurement(struct bh1730_data *bh1730)
+{
+ ndelay(bh1730_itime_ns(bh1730) + BH1730_INTERNAL_CLOCK_NS * 714);
+}
+
+static int bh1730_adjust_gain(struct bh1730_data *bh1730)
+{
+ int visible, ir, highest, 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)
+ highest *= 128;
+ else
+ highest = (highest * 128) / bh1730_gain_multiplier(bh1730);
+
+ /*
+ * 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) / 128;
+
+ 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 s64 bh1730_get_millilux(struct bh1730_data *bh1730)
+{
+ int visible, ir, visible_coef, ir_coef;
+ u64 itime_us = bh1730_itime_ns(bh1730) / NSEC_PER_USEC;
+ 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 = (u64)USEC_PER_MSEC * (visible_coef * visible - ir_coef * ir);
+ millilux /= bh1730_gain_multiplier(bh1730);
+ millilux *= 103;
+ millilux /= itime_us;
+ return 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 ret;
+ s64 millilux;
+
+ ret = bh1730_adjust_gain(bh1730);
+ if (ret < 0)
+ return ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ millilux = bh1730_get_millilux(bh1730);
+ if (millilux < 0)
+ return millilux;
+ *val = millilux / 1000;
+ *val2 = (millilux % 1000) * 1000;
+ return IIO_VAL_INT_PLUS_MICRO;
+ case IIO_CHAN_INFO_RAW:
+ switch (chan->channel2) {
+ case IIO_MOD_LIGHT_CLEAR:
+ ret = bh1730_read_word(bh1730, BH1730_REG_DATA0LOW);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ return IIO_VAL_INT;
+ case IIO_MOD_LIGHT_IR:
+ ret = bh1730_read_word(bh1730, BH1730_REG_DATA1LOW);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+ case IIO_CHAN_INFO_SCALE:
+ *val = bh1730_gain_multiplier(bh1730);
+ return IIO_VAL_INT;
+ 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,
+ .modified = 1,
+ .channel2 = IIO_MOD_LIGHT_BOTH,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+ },
+ {
+ .type = IIO_LIGHT,
+ .modified = 1,
+ .channel2 = IIO_MOD_LIGHT_CLEAR,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ },
+ {
+ .type = IIO_LIGHT,
+ .modified = 1,
+ .channel2 = IIO_MOD_LIGHT_IR,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+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);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id of_bh1730_match[] = {
+ { .compatible = "rohm,bh1730fvc" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_bh1730_match);
+#endif
+
+static struct i2c_driver bh1730_driver = {
+ .probe_new = bh1730_probe,
+ .remove = bh1730_remove,
+ .driver = {
+ .name = "bh1730",
+ .of_match_table = of_match_ptr(of_bh1730_match),
+ },
+};
+module_i2c_driver(bh1730_driver);
+
+MODULE_AUTHOR("Pierre Bourdon <delroth@xxxxxxxxxx>");
+MODULE_DESCRIPTION("ROHM BH1730FVC driver");
+MODULE_LICENSE("GPL v2");
--
2.16.1.291.g4437f3f132-goog