Re: [PATCH] iio: light: add driver for bh1730fvc chips
From: Daniel Baluta
Date: Wed Feb 21 2018 - 10:31:39 EST
Hi Pierre,
Few comments inline:
On Wed, Feb 21, 2018 at 2:55 PM, Pierre Bourdon <delroth@xxxxxxxxxx> wrote:
> Ambient light sensor that supports visible light and IR measurements and
> configurable gain/integration time.
>
Can you have a quick look to existing ROHM light sensor support.
Perhaps your sensor
is similar enough with existing code.
I'm talking about:
drivers/iio/light/{bh1750.c bh1780.c }
> Signed-off-by: Pierre Bourdon <delroth@xxxxxxxxxx>
> ---
> .../devicetree/bindings/iio/light/bh1730.txt | 15 +
> drivers/iio/light/Kconfig | 10 +
> drivers/iio/light/Makefile | 1 +
> drivers/iio/light/bh1730.c | 429 ++++++++++++++++++
> 4 files changed, 455 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/light/bh1730.txt
> create mode 100644 drivers/iio/light/bh1730.c
>
> diff --git a/Documentation/devicetree/bindings/iio/light/bh1730.txt b/Documentation/devicetree/bindings/iio/light/bh1730.txt
> new file mode 100644
> index 000000000000..6b38c4010647
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/light/bh1730.txt
> @@ -0,0 +1,15 @@
> +* ROHM BH1730FVC ambient light sensor
> +
> +http://www.rohm.com/web/global/products/-/product/BH1730FVC
> +
> +Required properties:
> +
> + - compatible : should be "rohm,bh1730fvc"
> + - reg : the I2C address of the sensor
> +
> +Example:
> +
> +bh1730fvc@29 {
> + compatible = "rohm,bh1730fvc";
> + reg = <0x29>;
> +};
Usually the devicetree binding part should be sent as a separate patch
with device-tree mailing list and maintainer at CC.
Use ./scripts/get_maintainer.pl to find the exact emails.
Mind that you should sent a patchseries:
1/2 - driver code
2/2 - documentation
> 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..6912aaa3295b
> --- /dev/null
> +++ b/drivers/iio/light/bh1730.c
> @@ -0,0 +1,429 @@
> +// 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)
> +{
> + int ret;
> + int control =
> + BH1730_CONTROL_POWER_ON |
> + BH1730_CONTROL_MEASURE;
> +
> + ret = bh1730_write(bh1730, BH1730_REG_CONTROL, control);
> + if (ret < 0)
> + return ret;
Directly return bh1730_write , remove ret and control. Similar with power_off.
> + return 0;
> +}
> +
> +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,
> + const struct i2c_device_id *id)
> +{
> + 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 i2c_device_id bh1730_id[] = {
> + { "bh1730", 0 },
> + {},
> +};
> +MODULE_DEVICE_TABLE(i2c, bh1730_id);
> +
> +#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 = bh1730_probe,
I wonder if you can use the probe_new API here.
e.g
https://patchwork.kernel.org/patch/9395073/
> + .remove = bh1730_remove,
> + .id_table = bh1730_id,
> + .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");
>