/**
 * rescan the pci bus on insert
 * Jan Dittmer <jdittmer@ppp0.net>
 *
 * heavily based on a similar module from
 * Vladimir Kondratiev, vladimir.kondratiev@intel.com
 */
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/errno.h>

/**
 * Rescan slot.
 * First, determine whether card in the slot has changed. It is
 * done by compare of old and actual devices for function 0.
 * If change detected, old device(s) removed, other functions
 * scanned if it is multi-function dev, new devices inserted.
 * 
 * @param temp   Device template. Should be set: bus and devfn.
 * @return Device for function 0
 */
void pci_rescan_slot(struct pci_dev *temp)
{
	struct pci_bus *bus = temp->bus;
	struct pci_dev* old_dev = pci_find_slot(bus->number,temp->devfn);
	struct pci_dev *dev = NULL;
	int func = 0;
	int new_multi = 0;  /* new multifunction device */
	u8 hdr_type;
	/* function 0 */
	if (!pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type)) {
		temp->hdr_type = hdr_type & 0x7f;
		new_multi=hdr_type & 0x80;
		if (!old_dev) {
			dev = pci_scan_single_device(bus, temp->devfn);
			if (dev) {
				printk("Found new device on %s function %x:%x %x\n",
						bus->name, temp->devfn >> 3,
						temp->devfn & 7,
						hdr_type);
				pci_bus_add_device(dev);
			}
		}
		if (new_multi) { /* continue scanning for other functions */
/*			printk("Scanning subfunctions\n"); */
			for (func = 1, temp->devfn++; func < 8; func++, temp->devfn++) {
				//	printk("%x\n", func);
				if (pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type))
					continue;
				temp->hdr_type = hdr_type & 0x7f;

				old_dev = pci_find_slot(bus->number, temp->devfn);
				if (!old_dev) {
					dev = pci_scan_single_device(bus, temp->devfn);
					if (dev) {
						printk("Found new device on %s function %x:%x %x\n",
								bus->name, temp->devfn >> 3,
								temp->devfn & 7,
								hdr_type);
						printk("Prettyname %s\n", dev->pretty_name);
						// from drivers/pci/bus.c, pci_bus_add_devices
						pci_bus_add_device(dev);
					}
				} 
			}
		}
	}
}


/**
 * Rescan PCI bus.
 * Assumed, some slots may have changed its content.
 * Find old information about each slot and the new one.
 * If they match, do nothing. Otherwise,
 * remove/insert proper devices.
 * 
 * @param bus
 */
static void pci_rescan_bus(const struct pci_bus *bus)
{
	unsigned int devfn;
	struct pci_dev dev0;

	memset(&dev0, 0, sizeof(dev0));
	dev0.bus = (struct pci_bus*)bus;
	dev0.sysdata = bus->sysdata;
	for (devfn = 0; devfn < 0x100; devfn += 8) {
		dev0.devfn = devfn;
		pci_rescan_slot(&dev0);
	}
}

static void pci_rescan_buses(const struct list_head *list)
{
	const struct list_head *l;
	list_for_each(l,list) {
		const struct pci_bus *b = pci_bus_b(l);
		/*
		printk("Scanning Bus %d:%d:%d, %s\n", b->number,
				b->primary, b->secondary, b->name);
		*/
		pci_rescan_bus(b);
		pci_rescan_buses(&b->children);
	}
}



static int pci_rescan_init(void)
{
	pci_rescan_buses(&pci_root_buses);
	return -ENODEV;
}

static void pci_rescan_exit(void)
{}


module_init(pci_rescan_init);
module_exit(pci_rescan_exit);

MODULE_DESCRIPTION("Do PCI bus rescan");
MODULE_AUTHOR("jdi");