drivers/iio/adc/ad7298.c

Source file repositories/reference/linux-study-clean/drivers/iio/adc/ad7298.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/adc/ad7298.c
Extension
.c
Size
8917 bytes
Lines
375
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 ad7298_state {
	struct spi_device		*spi;
	struct regulator		*reg;
	unsigned			ext_ref;
	struct spi_transfer		ring_xfer[10];
	struct spi_transfer		scan_single_xfer[3];
	struct spi_message		ring_msg;
	struct spi_message		scan_single_msg;
	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 */
	__be16				rx_buf[12] __aligned(IIO_DMA_MINALIGN);
	__be16				tx_buf[2];
};

#define AD7298_V_CHAN(index)						\
	{								\
		.type = IIO_VOLTAGE,					\
		.indexed = 1,						\
		.channel = index,					\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
		.address = index,					\
		.scan_index = index,					\
		.scan_type = {						\
			.sign = 'u',					\
			.realbits = 12,					\
			.storagebits = 16,				\
			.endianness = IIO_BE,				\
		},							\
	}

static const struct iio_chan_spec ad7298_channels[] = {
	{
		.type = IIO_TEMP,
		.indexed = 1,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_SCALE) |
			BIT(IIO_CHAN_INFO_OFFSET),
		.address = AD7298_CH_TEMP,
		.scan_index = -1,
		.scan_type = {
			.sign = 's',
			.realbits = 32,
			.storagebits = 32,
		},
	},
	AD7298_V_CHAN(0),
	AD7298_V_CHAN(1),
	AD7298_V_CHAN(2),
	AD7298_V_CHAN(3),
	AD7298_V_CHAN(4),
	AD7298_V_CHAN(5),
	AD7298_V_CHAN(6),
	AD7298_V_CHAN(7),
	IIO_CHAN_SOFT_TIMESTAMP(8),
};

/*
 * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
 */
static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
	const unsigned long *active_scan_mask)
{
	struct ad7298_state *st = iio_priv(indio_dev);
	int i, m;
	unsigned short command;
	int scan_count;

	/* Now compute overall size */
	scan_count = bitmap_weight(active_scan_mask,
				   iio_get_masklength(indio_dev));

	command = AD7298_WRITE | st->ext_ref;

	for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
		if (test_bit(i, active_scan_mask))
			command |= m;

	st->tx_buf[0] = cpu_to_be16(command);

	/* build spi ring message */
	st->ring_xfer[0].tx_buf = &st->tx_buf[0];
	st->ring_xfer[0].len = 2;
	st->ring_xfer[0].cs_change = 1;
	st->ring_xfer[1].tx_buf = &st->tx_buf[1];
	st->ring_xfer[1].len = 2;
	st->ring_xfer[1].cs_change = 1;

Annotation

Implementation Notes