drivers/iio/imu/smi240.c

Source file repositories/reference/linux-study-clean/drivers/iio/imu/smi240.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/imu/smi240.c
Extension
.c
Size
15577 bytes
Lines
621
Domain
Driver Families
Bucket
drivers/iio
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct smi240_data {
	struct regmap *regmap;
	u16 accel_filter_freq;
	u16 anglvel_filter_freq;
	u8 built_in_self_test_count;
	enum capture_mode capture;
	/*
	 * Ensure natural alignment for timestamp if present.
	 * Channel size: 2 bytes.
	 * Max length needed: 2 * 3 channels + temp channel + 2 bytes padding + 8 byte ts.
	 * If fewer channels are enabled, less space may be needed, as
	 * long as the timestamp is still aligned to 8 bytes.
	 */
	s16 buf[12] __aligned(8);

	__be32 spi_buf __aligned(IIO_DMA_MINALIGN);
};

enum {
	SMI240_TEMP_OBJECT,
	SMI240_SCAN_ACCEL_X,
	SMI240_SCAN_ACCEL_Y,
	SMI240_SCAN_ACCEL_Z,
	SMI240_SCAN_GYRO_X,
	SMI240_SCAN_GYRO_Y,
	SMI240_SCAN_GYRO_Z,
	SMI240_SCAN_TIMESTAMP,
};

static const struct iio_chan_spec smi240_channels[] = {
	SMI240_TEMP_CHANNEL(SMI240_TEMP_OBJECT),
	SMI240_DATA_CHANNEL(IIO_ACCEL, X, SMI240_SCAN_ACCEL_X),
	SMI240_DATA_CHANNEL(IIO_ACCEL, Y, SMI240_SCAN_ACCEL_Y),
	SMI240_DATA_CHANNEL(IIO_ACCEL, Z, SMI240_SCAN_ACCEL_Z),
	SMI240_DATA_CHANNEL(IIO_ANGL_VEL, X, SMI240_SCAN_GYRO_X),
	SMI240_DATA_CHANNEL(IIO_ANGL_VEL, Y, SMI240_SCAN_GYRO_Y),
	SMI240_DATA_CHANNEL(IIO_ANGL_VEL, Z, SMI240_SCAN_GYRO_Z),
	IIO_CHAN_SOFT_TIMESTAMP(SMI240_SCAN_TIMESTAMP),
};

static const int smi240_low_pass_freqs[] = { SMI240_LOW_BANDWIDTH_HZ,
					     SMI240_HIGH_BANDWIDTH_HZ };

static u8 smi240_crc3(u32 data, u8 init, u8 poly)
{
	u8 crc = init;
	u8 do_xor;
	s8 i = 31;

	do {
		do_xor = crc & 0x04;
		crc <<= 1;
		crc |= 0x01 & (data >> i);
		if (do_xor)
			crc ^= poly;

		crc &= SMI240_CRC_MASK;
	} while (--i >= 0);

	return crc;
}

static bool smi240_sensor_data_is_valid(u32 data)
{
	if (smi240_crc3(data, SMI240_CRC_INIT, SMI240_CRC_POLY) != 0)
		return false;

	if (FIELD_GET(SMI240_READ_SD_BIT_MASK, data) &
	    FIELD_GET(SMI240_READ_CS_BIT_MASK, data))
		return false;

	return true;
}

static int smi240_regmap_spi_read(void *context, const void *reg_buf,
				  size_t reg_size, void *val_buf,
				  size_t val_size)
{
	int ret;
	u32 request, response;
	u16 *val = val_buf;
	struct spi_device *spi = context;
	struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
	struct smi240_data *iio_priv_data = iio_priv(indio_dev);

	if (reg_size != 1 || val_size != 2)
		return -EINVAL;

	request = FIELD_PREP(SMI240_WRITE_BUS_ID_MASK, SMI240_BUS_ID);
	request |= FIELD_PREP(SMI240_WRITE_CAP_BIT_MASK, iio_priv_data->capture);

Annotation

Implementation Notes