Re: [PATCH v2 2/3] iio: light: ROHM BH1745 colour sensor

[Mudit Sharma <muditsharma.info@gmail.com>]

On 04/06/2024 00:10, Javier Carrasco wrote:
> On 03/06/2024 18:21, Mudit Sharma wrote:
>> Add support for BH1745, which is an I2C colour sensor with red, green,
>> blue and clear channels. It has a programmable active low interrupt pin.
>> Interrupt occurs when the signal from the selected interrupt source
>> channel crosses set interrupt threshold high or low level.
>>
>> This driver includes device attributes to configure the following:
>> - Interrupt pin latch: The interrupt pin can be configured to
>>    be latched (until interrupt register (0x60) is read or initialized)
>>    or update after each measurement.
>> - Interrupt source: The colour channel that will cause the interrupt
>>    when channel will cross the set threshold high or low level.
>>
>> This driver also includes device attributes to present valid
>> configuration options/values for:
>> - Integration time
>> - Interrupt colour source
>> - Hardware gain
>>
>> Signed-off-by: Mudit Sharma <muditsharma.info@gmail.com>
> 
> Hi Mudit,
> 
> a few minor comments inline.
> 
>> ---
>> v1->v2:
>> - No changes
>>
>>   drivers/iio/light/Kconfig  |  12 +
>>   drivers/iio/light/Makefile |   1 +
>>   drivers/iio/light/bh1745.c | 879 +++++++++++++++++++++++++++++++++++++
>>   3 files changed, 892 insertions(+)
>>   create mode 100644 drivers/iio/light/bh1745.c
>>
>> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
>> index 9a587d403118..6e0bd2addf9e 100644
>> --- a/drivers/iio/light/Kconfig
>> +++ b/drivers/iio/light/Kconfig
>> @@ -114,6 +114,18 @@ config AS73211
>>   	 This driver can also be built as a module.  If so, the module
>>   	 will be called as73211.
>>   
>> +config BH1745
>> +	tristate "ROHM BH1745 colour sensor"
>> +	depends on I2C
>> +	select REGMAP_I2C
>> +	select IIO_BUFFER
>> +	select IIO_TRIGGERED_BUFFER
>> +	help
>> +	  Say Y here to build support for the ROHM bh1745 colour sensor.
>> +
>> +	  To compile this driver as a module, choose M here: the module will
>> +	  be called bh1745.
>> +
>>   config BH1750
>>   	tristate "ROHM BH1750 ambient light sensor"
>>   	depends on I2C
>> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
>> index a30f906e91ba..939a701a06ac 100644
>> --- a/drivers/iio/light/Makefile
>> +++ b/drivers/iio/light/Makefile
>> @@ -13,6 +13,7 @@ obj-$(CONFIG_APDS9300)		+= apds9300.o
>>   obj-$(CONFIG_APDS9306)		+= apds9306.o
>>   obj-$(CONFIG_APDS9960)		+= apds9960.o
>>   obj-$(CONFIG_AS73211)		+= as73211.o
>> +obj-$(CONFIG_BH1745)		+= bh1745.o
>>   obj-$(CONFIG_BH1750)		+= bh1750.o
>>   obj-$(CONFIG_BH1780)		+= bh1780.o
>>   obj-$(CONFIG_CM32181)		+= cm32181.o
>> diff --git a/drivers/iio/light/bh1745.c b/drivers/iio/light/bh1745.c
>> new file mode 100644
>> index 000000000000..a7b660a1bdc8
>> --- /dev/null
>> +++ b/drivers/iio/light/bh1745.c
>> @@ -0,0 +1,879 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * ROHM BH1745 digital colour sensor driver
>> + *
>> + * Copyright (C) Mudit Sharma <muditsharma.info@gmail.com>
>> + *
>> + * 7-bit I2C slave addresses:
>> + *  0x38 (ADDR pin low)
>> + *  0x39 (ADDR pin high)
>> + *
>> + */
>> +
>> +#include <linux/i2c.h>
>> +#include <linux/mutex.h>
>> +#include <linux/util_macros.h>
>> +#include <linux/iio/events.h>
>> +#include <linux/regmap.h>
>> +
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/iio/trigger.h>
>> +#include <linux/iio/trigger_consumer.h>
>> +#include <linux/iio/triggered_buffer.h>
>> +
>> +#define BH1745_MOD_NAME "bh1745"
> 
> Given that this define is only used in one place, using the string
> directly is common practice in iio.
> 
>> +
>> +/* BH1745 config regs */
>> +#define BH1745_SYS_CTRL 0x40
>> +
>> +#define BH1745_MODE_CTRL_1 0x41
>> +#define BH1745_MODE_CTRL_2 0x42
>> +#define BH1745_MODE_CTRL_3 0x44
>> +
>> +#define BH1745_INTR 0x60
>> +#define BH1745_INTR_STATUS BIT(7)
>> +
>> +#define BH1745_PERSISTENCE 0x61
>> +
>> +#define BH1745_TH_LSB 0X62
>> +#define BH1745_TH_MSB 0X63
>> +
>> +#define BH1745_TL_LSB 0X64
>> +#define BH1745_TL_MSB 0X65
>> +
>> +#define BH1745_THRESHOLD_MAX 0xFFFF
>> +#define BH1745_THRESHOLD_MIN 0x0
>> +
>> +#define BH1745_MANU_ID 0X92
>> +
>> +/* BH1745 output regs */
>> +#define BH1745_R_LSB 0x50
>> +#define BH1745_R_MSB 0x51
>> +#define BH1745_G_LSB 0x52
>> +#define BH1745_G_MSB 0x53
>> +#define BH1745_B_LSB 0x54
>> +#define BH1745_B_MSB 0x55
>> +#define BH1745_CLR_LSB 0x56
>> +#define BH1745_CLR_MSB 0x57
>> +
>> +#define BH1745_SW_RESET BIT(7)
>> +#define BH1745_INT_RESET BIT(6)
>> +
>> +#define BH1745_MEASUREMENT_TIME_MASK GENMASK(2, 0)
>> +
>> +#define BH1745_RGBC_EN BIT(4)
>> +
>> +#define BH1745_ADC_GAIN_MASK GENMASK(1, 0)
>> +
>> +#define BH1745_INT_ENABLE BIT(0)
>> +#define BH1745_INT_SIGNAL_ACTIVE BIT(7)
>> +
>> +#define BH1745_INT_SIGNAL_LATCHED BIT(4)
>> +#define BH1745_INT_SIGNAL_LATCH_OFFSET 4
>> +
>> +#define BH1745_INT_SOURCE_MASK GENMASK(3, 2)
>> +#define BH1745_INT_SOURCE_OFFSET 2
>> +
>> +#define BH1745_INT_TIME_AVAILABLE "0.16 0.32 0.64 1.28 2.56 5.12"
>> +#define BH1745_HARDWAREGAIN_AVAILABLE "1 2 16"
>> +#define BH1745_INT_COLOUR_CHANNEL_AVAILABLE \
>> +	"0 (Red Channel) 1 (Green Channel) 2 (Blue channel) 3 (Clear channel)"
>> +
>> +static const int bh1745_int_time[][2] = {
>> +	{ 0, 160000 }, /* 160 ms */
>> +	{ 0, 320000 }, /* 320 ms */
>> +	{ 0, 640000 }, /* 640 ms */
>> +	{ 1, 280000 }, /* 1280 ms */
>> +	{ 2, 560000 }, /* 2560 ms */
>> +	{ 5, 120000 }, /* 5120 ms */
>> +};
>> +
>> +static const u8 bh1745_gain_factor[] = { 1, 2, 16 };
>> +
>> +enum {
>> +	BH1745_INT_SOURCE_RED,
>> +	BH1745_INT_SOURCE_GREEN,
>> +	BH1745_INT_SOURCE_BLUE,
>> +	BH1745_INT_SOURCE_CLEAR,
>> +} bh1745_int_source;
>> +
>> +enum {
>> +	BH1745_ADC_GAIN_1X,
>> +	BH1745_ADC_GAIN_2X,
>> +	BH1745_ADC_GAIN_16X,
>> +} bh1745_gain;
>> +
>> +enum {
>> +	BH1745_MEASUREMENT_TIME_160MS,
>> +	BH1745_MEASUREMENT_TIME_320MS,
>> +	BH1745_MEASUREMENT_TIME_640MS,
>> +	BH1745_MEASUREMENT_TIME_1280MS,
>> +	BH1745_MEASUREMENT_TIME_2560MS,
>> +	BH1745_MEASUREMENT_TIME_5120MS,
>> +} bh1745_measurement_time;
>> +
>> +enum {
>> +	BH1745_PRESISTENCE_UPDATE_TOGGLE,
>> +	BH1745_PRESISTENCE_UPDATE_EACH_MEASUREMENT,
>> +	BH1745_PRESISTENCE_UPDATE_FOUR_MEASUREMENT,
>> +	BH1745_PRESISTENCE_UPDATE_EIGHT_MEASUREMENT,
>> +} bh1745_presistence_value;
>> +
>> +struct bh1745_data {
>> +	struct mutex lock;
>> +	struct regmap *regmap;
>> +	struct i2c_client *client;
>> +	struct iio_trigger *trig;
>> +	u8 mode_ctrl1;
>> +	u8 mode_ctrl2;
>> +	u8 int_src;
>> +	u8 int_latch;
>> +	u8 interrupt;
>> +};
>> +
>> +static const struct regmap_range bh1745_volatile_ranges[] = {
>> +	regmap_reg_range(BH1745_MODE_CTRL_2, BH1745_MODE_CTRL_2), /* VALID */
>> +	regmap_reg_range(BH1745_R_LSB, BH1745_CLR_MSB), /* Data */
>> +	regmap_reg_range(BH1745_INTR, BH1745_INTR), /* Interrupt */
>> +};
>> +
>> +static const struct regmap_access_table bh1745_volatile_regs = {
>> +	.yes_ranges = bh1745_volatile_ranges,
>> +	.n_yes_ranges = ARRAY_SIZE(bh1745_volatile_ranges),
>> +};
>> +
>> +static const struct regmap_range bh1745_read_ranges[] = {
>> +	regmap_reg_range(BH1745_SYS_CTRL, BH1745_MODE_CTRL_2),
>> +	regmap_reg_range(BH1745_R_LSB, BH1745_CLR_MSB),
>> +	regmap_reg_range(BH1745_INTR, BH1745_INTR),
>> +	regmap_reg_range(BH1745_PERSISTENCE, BH1745_TL_MSB),
>> +	regmap_reg_range(BH1745_MANU_ID, BH1745_MANU_ID),
>> +};
>> +
>> +static const struct regmap_access_table bh1745_ro_regs = {
>> +	.yes_ranges = bh1745_read_ranges,
>> +	.n_yes_ranges = ARRAY_SIZE(bh1745_read_ranges),
>> +};
>> +
>> +static const struct regmap_range bh1745_writable_ranges[] = {
>> +	regmap_reg_range(BH1745_SYS_CTRL, BH1745_MODE_CTRL_2),
>> +	regmap_reg_range(BH1745_PERSISTENCE, BH1745_TL_MSB),
>> +};
>> +
>> +static const struct regmap_access_table bh1745_wr_regs = {
>> +	.yes_ranges = bh1745_writable_ranges,
>> +	.n_yes_ranges = ARRAY_SIZE(bh1745_writable_ranges),
>> +};
>> +
>> +static const struct regmap_config bh1745_regmap = {
>> +	.reg_bits = 8,
>> +	.val_bits = 8,
>> +	.max_register = BH1745_MANU_ID,
>> +	.cache_type = REGCACHE_RBTREE,
>> +	.volatile_table = &bh1745_volatile_regs,
>> +	.wr_table = &bh1745_wr_regs,
>> +	.rd_table = &bh1745_ro_regs,
>> +};
>> +
>> +static const struct iio_event_spec bh1745_event_spec[] = {
>> +	{
>> +		.type = IIO_EV_TYPE_THRESH,
>> +		.dir = IIO_EV_DIR_RISING,
>> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
>> +	},
>> +	{
>> +		.type = IIO_EV_TYPE_THRESH,
>> +		.dir = IIO_EV_DIR_FALLING,
>> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
>> +	},
>> +	{
>> +		.type = IIO_EV_TYPE_THRESH,
>> +		.dir = IIO_EV_DIR_EITHER,
>> +		.mask_shared_by_type = BIT(IIO_EV_INFO_PERIOD),
>> +	},
>> +};
>> +
>> +#define BH1745_CHANNEL(_colour, _si, _addr)                                   \
>> +	{                                                                     \
>> +		.type = IIO_INTENSITY, .modified = 1,                         \
>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                 \
>> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_HARDWAREGAIN) | \
>> +					    BIT(IIO_CHAN_INFO_INT_TIME),      \
>> +		.event_spec = bh1745_event_spec,                              \
>> +		.num_event_specs = ARRAY_SIZE(bh1745_event_spec),             \
>> +		.channel2 = IIO_MOD_LIGHT_##_colour, .address = _addr,        \
>> +		.scan_index = _si,                                            \
>> +		.scan_type = {                                                \
>> +			.sign = 'u',                                          \
>> +			.realbits = 16,                                       \
>> +			.storagebits = 16,                                    \
>> +			.endianness = IIO_CPU,                                \
>> +		},                                                            \
>> +	}
>> +
>> +static const struct iio_chan_spec bh1745_channels[] = {
>> +	BH1745_CHANNEL(RED, 0, BH1745_R_LSB),
>> +	BH1745_CHANNEL(GREEN, 1, BH1745_G_LSB),
>> +	BH1745_CHANNEL(BLUE, 2, BH1745_B_LSB),
>> +	BH1745_CHANNEL(CLEAR, 3, BH1745_CLR_LSB),
>> +	IIO_CHAN_SOFT_TIMESTAMP(4),
>> +};
>> +
>> +static int bh1745_write_value(struct bh1745_data *data, u8 reg, void *value,
>> +			      size_t len)
>> +{
> 
> The initial assignment is unnecessary, as a new assignment is made
> immediately. This applies to several declarations of ret in this driver,
> but not always (e.g. bh1745_setup_trigger()).
> 
>> +	int ret = 0;
>> +
>> +	ret = regmap_bulk_write(data->regmap, reg, value, len);
>> +	if (ret < 0) {
>> +		dev_err(&data->client->dev,
>> +			"Failed to write to sensor. Reg: 0x%x\n", reg);
>> +		return ret;
>> +	}
> 
> Nit: black line before return (it applies to several functions in this
> driver, but again, not in all of them).

Hi Javier,

Thank you for the review on this.

Can you please point me to resource/section of code style guide for 
reference which talks about new line before 'return'.

Best regards,
Mudit Sharma