drivers/comedi/drivers/comedi_8255.c

Source file repositories/reference/linux-study-clean/drivers/comedi/drivers/comedi_8255.c

File Facts

System
Linux kernel
Corpus path
drivers/comedi/drivers/comedi_8255.c
Extension
.c
Size
7467 bytes
Lines
265
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

struct subdev_8255_private {
	unsigned long context;
	int (*io)(struct comedi_device *dev, int dir, int port, int data,
		  unsigned long context);
};

#ifdef CONFIG_HAS_IOPORT

static int subdev_8255_io(struct comedi_device *dev,
			  int dir, int port, int data, unsigned long regbase)
{
	if (dir) {
		outb(data, dev->iobase + regbase + port);
		return 0;
	}
	return inb(dev->iobase + regbase + port);
}

#endif /* CONFIG_HAS_IOPORT */

static int subdev_8255_mmio(struct comedi_device *dev,
			    int dir, int port, int data, unsigned long regbase)
{
	if (dir) {
		writeb(data, dev->mmio + regbase + port);
		return 0;
	}
	return readb(dev->mmio + regbase + port);
}

static int subdev_8255_insn(struct comedi_device *dev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn,
			    unsigned int *data)
{
	struct subdev_8255_private *spriv = s->private;
	unsigned long context = spriv->context;
	unsigned int mask;
	unsigned int v;

	mask = comedi_dio_update_state(s, data);
	if (mask) {
		if (mask & 0xff)
			spriv->io(dev, 1, I8255_DATA_A_REG,
				  s->state & 0xff, context);
		if (mask & 0xff00)
			spriv->io(dev, 1, I8255_DATA_B_REG,
				  (s->state >> 8) & 0xff, context);
		if (mask & 0xff0000)
			spriv->io(dev, 1, I8255_DATA_C_REG,
				  (s->state >> 16) & 0xff, context);
	}

	v = spriv->io(dev, 0, I8255_DATA_A_REG, 0, context);
	v |= (spriv->io(dev, 0, I8255_DATA_B_REG, 0, context) << 8);
	v |= (spriv->io(dev, 0, I8255_DATA_C_REG, 0, context) << 16);

	data[1] = v;

	return insn->n;
}

static void subdev_8255_do_config(struct comedi_device *dev,
				  struct comedi_subdevice *s)
{
	struct subdev_8255_private *spriv = s->private;
	unsigned long context = spriv->context;
	int config;

	config = I8255_CTRL_CW;
	/* 1 in io_bits indicates output, 1 in config indicates input */
	if (!(s->io_bits & 0x0000ff))
		config |= I8255_CTRL_A_IO;
	if (!(s->io_bits & 0x00ff00))
		config |= I8255_CTRL_B_IO;
	if (!(s->io_bits & 0x0f0000))
		config |= I8255_CTRL_C_LO_IO;
	if (!(s->io_bits & 0xf00000))
		config |= I8255_CTRL_C_HI_IO;

	spriv->io(dev, 1, I8255_CTRL_REG, config, context);
}

static int subdev_8255_insn_config(struct comedi_device *dev,
				   struct comedi_subdevice *s,
				   struct comedi_insn *insn,
				   unsigned int *data)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int mask;

Annotation

Implementation Notes