static int pci9118_ai_setup_dma()

in drivers/adl_pci9118.c [798:914]

• 88 lines of code
• 15 McCabe index (conditional complexity)

static int pci9118_ai_setup_dma(struct comedi_device *dev,
				struct comedi_subdevice *s)
{
	struct pci9118_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	struct pci9118_dmabuf *dmabuf0 = &devpriv->dmabuf[0];
	struct pci9118_dmabuf *dmabuf1 = &devpriv->dmabuf[1];
	unsigned int dmalen0 = dmabuf0->size;
	unsigned int dmalen1 = dmabuf1->size;
	unsigned int scan_bytes = devpriv->ai_n_realscanlen *
				  comedi_bytes_per_sample(s);

	/* isn't output buff smaller that our DMA buff? */
	if (dmalen0 > s->async->prealloc_bufsz) {
		/* align to 32bit down */
		dmalen0 = s->async->prealloc_bufsz & ~3L;
	}
	if (dmalen1 > s->async->prealloc_bufsz) {
		/* align to 32bit down */
		dmalen1 = s->async->prealloc_bufsz & ~3L;
	}

	/* we want wake up every scan? */
	if (devpriv->ai_flags & CMDF_WAKE_EOS) {
		if (dmalen0 < scan_bytes) {
			/* uff, too short DMA buffer, disable EOS support! */
			devpriv->ai_flags &= (~CMDF_WAKE_EOS);
			dev_info(dev->class_dev,
				 "WAR: DMA0 buf too short, can't support CMDF_WAKE_EOS (%d<%d)\n",
				  dmalen0, scan_bytes);
		} else {
			/* short first DMA buffer to one scan */
			dmalen0 = scan_bytes;
			if (dmalen0 < 4) {
				dev_info(dev->class_dev,
					 "ERR: DMA0 buf len bug? (%d<4)\n",
					 dmalen0);
				dmalen0 = 4;
			}
		}
	}
	if (devpriv->ai_flags & CMDF_WAKE_EOS) {
		if (dmalen1 < scan_bytes) {
			/* uff, too short DMA buffer, disable EOS support! */
			devpriv->ai_flags &= (~CMDF_WAKE_EOS);
			dev_info(dev->class_dev,
				 "WAR: DMA1 buf too short, can't support CMDF_WAKE_EOS (%d<%d)\n",
				 dmalen1, scan_bytes);
		} else {
			/* short second DMA buffer to one scan */
			dmalen1 = scan_bytes;
			if (dmalen1 < 4) {
				dev_info(dev->class_dev,
					 "ERR: DMA1 buf len bug? (%d<4)\n",
					 dmalen1);
				dmalen1 = 4;
			}
		}
	}

	/* transfer without CMDF_WAKE_EOS */
	if (!(devpriv->ai_flags & CMDF_WAKE_EOS)) {
		unsigned int tmp;

		/* if it's possible then align DMA buffers to length of scan */
		tmp = dmalen0;
		dmalen0 = (dmalen0 / scan_bytes) * scan_bytes;
		dmalen0 &= ~3L;
		if (!dmalen0)
			dmalen0 = tmp;	/* uff. very long scan? */
		tmp = dmalen1;
		dmalen1 = (dmalen1 / scan_bytes) * scan_bytes;
		dmalen1 &= ~3L;
		if (!dmalen1)
			dmalen1 = tmp;	/* uff. very long scan? */
		/*
		 * if measure isn't neverending then test, if it fits whole
		 * into one or two DMA buffers
		 */
		if (!devpriv->ai_neverending) {
			unsigned long long scanlen;

			scanlen = (unsigned long long)scan_bytes *
				  cmd->stop_arg;

			/* fits whole measure into one DMA buffer? */
			if (dmalen0 > scanlen) {
				dmalen0 = scanlen;
				dmalen0 &= ~3L;
			} else {
				/* fits whole measure into two DMA buffer? */
				if (dmalen1 > (scanlen - dmalen0)) {
					dmalen1 = scanlen - dmalen0;
					dmalen1 &= ~3L;
				}
			}
		}
	}

	/* these DMA buffer size will be used */
	devpriv->dma_actbuf = 0;
	dmabuf0->use_size = dmalen0;
	dmabuf1->use_size = dmalen1;

	pci9118_amcc_dma_ena(dev, false);
	pci9118_amcc_setup_dma(dev, 0);
	/* init DMA transfer */
	outl(0x00000000 | AINT_WRITE_COMPL,
	     devpriv->iobase_a + AMCC_OP_REG_INTCSR);
/* outl(0x02000000|AINT_WRITE_COMPL, devpriv->iobase_a+AMCC_OP_REG_INTCSR); */
	pci9118_amcc_dma_ena(dev, true);
	outl(inl(devpriv->iobase_a + AMCC_OP_REG_INTCSR) | EN_A2P_TRANSFERS,
	     devpriv->iobase_a + AMCC_OP_REG_INTCSR);
						/* allow bus mastering */

	return 0;
}