static int hrz_probe()

in horizon.c [2607:2759]

• 108 lines of code
• 10 McCabe index (conditional complexity)

static int hrz_probe(struct pci_dev *pci_dev,
		     const struct pci_device_id *pci_ent)
{
	hrz_dev * dev;
	int err = 0;

	// adapter slot free, read resources from PCI configuration space
	u32 iobase = pci_resource_start (pci_dev, 0);
	u32 * membase = bus_to_virt (pci_resource_start (pci_dev, 1));
	unsigned int irq;
	unsigned char lat;

	PRINTD (DBG_FLOW, "hrz_probe");

	if (pci_enable_device(pci_dev))
		return -EINVAL;

	/* XXX DEV_LABEL is a guess */
	if (!request_region(iobase, HRZ_IO_EXTENT, DEV_LABEL)) {
		err = -EINVAL;
		goto out_disable;
	}

	dev = kzalloc(sizeof(hrz_dev), GFP_KERNEL);
	if (!dev) {
		// perhaps we should be nice: deregister all adapters and abort?
		PRINTD(DBG_ERR, "out of memory");
		err = -ENOMEM;
		goto out_release;
	}

	pci_set_drvdata(pci_dev, dev);

	// grab IRQ and install handler - move this someplace more sensible
	irq = pci_dev->irq;
	if (request_irq(irq,
			interrupt_handler,
			IRQF_SHARED, /* irqflags guess */
			DEV_LABEL, /* name guess */
			dev)) {
		PRINTD(DBG_WARN, "request IRQ failed!");
		err = -EINVAL;
		goto out_free;
	}

	PRINTD(DBG_INFO, "found Madge ATM adapter (hrz) at: IO %x, IRQ %u, MEM %p",
	       iobase, irq, membase);

	dev->atm_dev = atm_dev_register(DEV_LABEL, &pci_dev->dev, &hrz_ops, -1,
					NULL);
	if (!(dev->atm_dev)) {
		PRINTD(DBG_ERR, "failed to register Madge ATM adapter");
		err = -EINVAL;
		goto out_free_irq;
	}

	PRINTD(DBG_INFO, "registered Madge ATM adapter (no. %d) (%p) at %p",
	       dev->atm_dev->number, dev, dev->atm_dev);
	dev->atm_dev->dev_data = (void *) dev;
	dev->pci_dev = pci_dev; 

	// enable bus master accesses
	pci_set_master(pci_dev);

	// frobnicate latency (upwards, usually)
	pci_read_config_byte(pci_dev, PCI_LATENCY_TIMER, &lat);
	if (pci_lat) {
		PRINTD(DBG_INFO, "%s PCI latency timer from %hu to %hu",
		       "changing", lat, pci_lat);
		pci_write_config_byte(pci_dev, PCI_LATENCY_TIMER, pci_lat);
	} else if (lat < MIN_PCI_LATENCY) {
		PRINTK(KERN_INFO, "%s PCI latency timer from %hu to %hu",
		       "increasing", lat, MIN_PCI_LATENCY);
		pci_write_config_byte(pci_dev, PCI_LATENCY_TIMER, MIN_PCI_LATENCY);
	}

	dev->iobase = iobase;
	dev->irq = irq; 
	dev->membase = membase; 

	dev->rx_q_entry = dev->rx_q_reset = &memmap->rx_q_entries[0];
	dev->rx_q_wrap  = &memmap->rx_q_entries[RX_CHANS-1];

	// these next three are performance hacks
	dev->last_vc = -1;
	dev->tx_last = -1;
	dev->tx_idle = 0;

	dev->tx_regions = 0;
	dev->tx_bytes = 0;
	dev->tx_skb = NULL;
	dev->tx_iovec = NULL;

	dev->tx_cell_count = 0;
	dev->rx_cell_count = 0;
	dev->hec_error_count = 0;
	dev->unassigned_cell_count = 0;

	dev->noof_spare_buffers = 0;

	{
		unsigned int i;
		for (i = 0; i < TX_CHANS; ++i)
			dev->tx_channel_record[i] = -1;
	}

	dev->flags = 0;

	// Allocate cell rates and remember ASIC version
	// Fibre: ATM_OC3_PCR = 1555200000/8/270*260/53 - 29/53
	// Copper: (WRONG) we want 6 into the above, close to 25Mb/s
	// Copper: (plagarise!) 25600000/8/270*260/53 - n/53

	if (hrz_init(dev)) {
		// to be really pedantic, this should be ATM_OC3c_PCR
		dev->tx_avail = ATM_OC3_PCR;
		dev->rx_avail = ATM_OC3_PCR;
		set_bit(ultra, &dev->flags); // NOT "|= ultra" !
	} else {
		dev->tx_avail = ((25600000/8)*26)/(27*53);
		dev->rx_avail = ((25600000/8)*26)/(27*53);
		PRINTD(DBG_WARN, "Buggy ASIC: no TX bus-mastering.");
	}

	// rate changes spinlock
	spin_lock_init(&dev->rate_lock);

	// on-board memory access spinlock; we want atomic reads and
	// writes to adapter memory (handles IRQ and SMP)
	spin_lock_init(&dev->mem_lock);

	init_waitqueue_head(&dev->tx_queue);

	// vpi in 0..4, vci in 6..10
	dev->atm_dev->ci_range.vpi_bits = vpi_bits;
	dev->atm_dev->ci_range.vci_bits = 10-vpi_bits;

	timer_setup(&dev->housekeeping, do_housekeeping, 0);
	mod_timer(&dev->housekeeping, jiffies);

out:
	return err;

out_free_irq:
	free_irq(irq, dev);
out_free:
	kfree(dev);
out_release:
	release_region(iobase, HRZ_IO_EXTENT);
out_disable:
	pci_disable_device(pci_dev);
	goto out;
}