drivers/comedi/drivers/das08.c

Source file repositories/reference/linux-study-clean/drivers/comedi/drivers/das08.c

File Facts

System
Linux kernel
Corpus path
drivers/comedi/drivers/das08.c
Extension
.c
Size
12923 bytes
Lines
459
Domain
Driver Families
Bucket
drivers/comedi
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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

if (board->ai_encoding == das08_encode12) {
			data[n] = (lsb >> 4) | (msb << 4);
		} else if (board->ai_encoding == das08_pcm_encode12) {
			data[n] = (msb << 8) + lsb;
		} else if (board->ai_encoding == das08_encode16) {
			/*
			 * "JR" 16-bit boards are sign-magnitude.
			 *
			 * XXX The manual seems to imply that 0 is full-scale
			 * negative and 65535 is full-scale positive, but the
			 * original COMEDI patch to add support for the
			 * DAS08/JR/16 and DAS08/JR/16-AO boards have it
			 * encoded as sign-magnitude.  Assume the original
			 * COMEDI code is correct for now.
			 */
			unsigned int magnitude = lsb | ((msb & 0x7f) << 8);

			/*
			 * MSB bit 7 is 0 for negative, 1 for positive voltage.
			 * COMEDI 16-bit bipolar data value for 0V is 0x8000.
			 */
			if (msb & 0x80)
				data[n] = BIT(15) + magnitude;
			else
				data[n] = BIT(15) - magnitude;
		} else {
			dev_err(dev->class_dev, "bug! unknown ai encoding\n");
			return -1;
		}
	}

	return n;
}

static int das08_di_insn_bits(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      struct comedi_insn *insn, unsigned int *data)
{
	data[0] = 0;
	data[1] = DAS08_STATUS_DI(inb(dev->iobase + DAS08_STATUS_REG));

	return insn->n;
}

static int das08_do_insn_bits(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      struct comedi_insn *insn, unsigned int *data)
{
	struct das08_private_struct *devpriv = dev->private;

	if (comedi_dio_update_state(s, data)) {
		/* prevent race with setting of analog input mux */
		spin_lock(&dev->spinlock);
		devpriv->do_mux_bits &= ~DAS08_CONTROL_DO_MASK;
		devpriv->do_mux_bits |= DAS08_CONTROL_DO(s->state);
		outb(devpriv->do_mux_bits, dev->iobase + DAS08_CONTROL_REG);
		spin_unlock(&dev->spinlock);
	}

	data[1] = s->state;

	return insn->n;
}

static int das08jr_di_insn_bits(struct comedi_device *dev,
				struct comedi_subdevice *s,
				struct comedi_insn *insn, unsigned int *data)
{
	data[0] = 0;
	data[1] = inb(dev->iobase + DAS08JR_DI_REG);

	return insn->n;
}

static int das08jr_do_insn_bits(struct comedi_device *dev,
				struct comedi_subdevice *s,
				struct comedi_insn *insn, unsigned int *data)
{
	if (comedi_dio_update_state(s, data))
		outb(s->state, dev->iobase + DAS08JR_DO_REG);

	data[1] = s->state;

	return insn->n;
}

static void das08_ao_set_data(struct comedi_device *dev,
			      unsigned int chan, unsigned int data)
{
	const struct das08_board_struct *board = dev->board_ptr;

Annotation

Implementation Notes