drivers/comedi/drivers/pcmad.c

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

File Facts

System
Linux kernel
Corpus path
drivers/comedi/drivers/pcmad.c
Extension
.c
Size
3595 bytes
Lines
151
Domain
Driver Families
Bucket
drivers/comedi
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 pcmad_board_struct {
	const char *name;
	unsigned int ai_maxdata;
};

static const struct pcmad_board_struct pcmad_boards[] = {
	{
		.name		= "pcmad12",
		.ai_maxdata	= 0x0fff,
	}, {
		.name		= "pcmad16",
		.ai_maxdata	= 0xffff,
	},
};

static int pcmad_ai_eoc(struct comedi_device *dev,
			struct comedi_subdevice *s,
			struct comedi_insn *insn,
			unsigned long context)
{
	unsigned int status;

	status = inb(dev->iobase + PCMAD_STATUS);
	if ((status & 0x3) == 0x3)
		return 0;
	return -EBUSY;
}

static int pcmad_ai_insn_read(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      struct comedi_insn *insn,
			      unsigned int *data)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int range = CR_RANGE(insn->chanspec);
	unsigned int val;
	int ret;
	int i;

	for (i = 0; i < insn->n; i++) {
		outb(chan, dev->iobase + PCMAD_CONVERT);

		ret = comedi_timeout(dev, s, insn, pcmad_ai_eoc, 0);
		if (ret)
			return ret;

		val = inb(dev->iobase + PCMAD_LSB) |
		      (inb(dev->iobase + PCMAD_MSB) << 8);

		/* data is shifted on the pcmad12, fix it */
		if (s->maxdata == 0x0fff)
			val >>= 4;

		if (comedi_range_is_bipolar(s, range)) {
			/* munge the two's complement value */
			val ^= ((s->maxdata + 1) >> 1);
		}

		data[i] = val;
	}

	return insn->n;
}

static int pcmad_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
	const struct pcmad_board_struct *board = dev->board_ptr;
	struct comedi_subdevice *s;
	int ret;

	ret = comedi_check_request_region(dev, it->options[0], 0x04,
					  0, 0x3ff, 4);
	if (ret)
		return ret;

	ret = comedi_alloc_subdevices(dev, 1);
	if (ret)
		return ret;

	s = &dev->subdevices[0];
	s->type		= COMEDI_SUBD_AI;
	if (it->options[1]) {
		/* 8 differential channels */
		s->subdev_flags	= SDF_READABLE | AREF_DIFF;
		s->n_chan	= 8;
	} else {
		/* 16 single-ended channels */
		s->subdev_flags	= SDF_READABLE | AREF_GROUND;
		s->n_chan	= 16;
	}

Annotation

Implementation Notes