pcie_slot.c

[Matthew Wilcox <matthew@xxxxxx>]

This is the code I've been using to test the cur/max bus speed changes.
It creates a pci_slot for every PCIe bridge in the system that claims
to have a slot.  Unfortunately, my motherboard manufacturer (Asus)
didn't bother to set the Slot bits correctly, so it looks like this:

ls /sys/bus/pci/slots/
0  0-1  0-2  0-3  0-4  1  1-1  2  2-1  3  5  6

I should have slots labelled 1 to 6, but several of the links which are
to onboard devices still have the Slot bits set, and a lot of the Slot
numbers are programmed incorrectly (eg they're the logical slot of that
downstream port, not the physical slot number).

I suspect this is fairly common, so I'm not asking for this code to
be merged.  It's interesting for testing purposes though.

#include <linux/init.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>

static void pcie_slot_create(struct pci_dev *dev)
{
	u32 sltcap;
	char name[8];

	pci_read_config_dword(dev, pci_pcie_cap(dev) + PCI_EXP_SLTCAP, &sltcap);
	sprintf(name, "%d", sltcap >> 19);
	pci_create_slot(dev->subordinate, 0, name, NULL);
}

static int has_slot(struct pci_dev *dev)
{
	u16 flags;
	unsigned cap = pci_pcie_cap(dev);
	if (!cap)
		return 0;
	pci_read_config_word(dev, cap + PCI_EXP_FLAGS, &flags);
	return flags & PCI_EXP_FLAGS_SLOT;
}

static void pcie_slot_destroy(struct pci_dev *dev)
{
	pci_destroy_slot(list_first_entry(&dev->subordinate->slots,
						struct pci_slot, list));
}

static void pcie_slot_exit(void)
{
	struct pci_dev *dev = NULL;

	for_each_pci_dev(dev) {
		if (has_slot(dev))
			pcie_slot_destroy(dev);
	}
}

static int pcie_slot_init(void)
{
	struct pci_dev *dev = NULL;

	for_each_pci_dev(dev) {
		if (has_slot(dev))
			pcie_slot_create(dev);
	}

	return 0;
}

module_init(pcie_slot_init);
module_exit(pcie_slot_exit);

MODULE_LICENSE("GPL");

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html