linux/drivers/pci/search.c
Jacek Lawrynowicz 338c3149a2 PCI: Add support for multiple DMA aliases
Solve IOMMU support issues with PCIe non-transparent bridges that use
Requester ID look-up tables (RID-LUT), e.g., the PEX8733.

The NTB connects devices in two independent PCI domains.  Devices separated
by the NTB are not able to discover each other.  A PCI packet being
forwared from one domain to another has to have its RID modified so it
appears on correct bus and completions are forwarded back to the original
domain through the NTB.  The RID is translated using a preprogrammed table
(LUT) and the PCI packet propagates upstream away from the NTB.  If the
destination system has IOMMU enabled, the packet will be discarded because
the new RID is unknown to the IOMMU.  Adding a DMA alias for the new RID
allows IOMMU to properly recognize the packet.

Each device behind the NTB has a unique RID assigned in the RID-LUT.  The
current DMA alias implementation supports only a single alias, so it's not
possible to support mutiple devices behind the NTB when IOMMU is enabled.

Enable all possible aliases on a given bus (256) that are stored in a
bitset.  Alias devfn is directly translated to a bit number.  The bitset is
not allocated for devices that have no need for DMA aliases.

More details can be found in the following article:
http://www.plxtech.com/files/pdf/technical/expresslane/RTC_Enabling%20MulitHostSystemDesigns.pdf

Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
2016-04-11 14:34:32 -05:00

391 lines
12 KiB
C

/*
* PCI searching functions.
*
* Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
* David Mosberger-Tang
* Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
* Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
*/
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include "pci.h"
DECLARE_RWSEM(pci_bus_sem);
EXPORT_SYMBOL_GPL(pci_bus_sem);
/*
* pci_for_each_dma_alias - Iterate over DMA aliases for a device
* @pdev: starting downstream device
* @fn: function to call for each alias
* @data: opaque data to pass to @fn
*
* Starting @pdev, walk up the bus calling @fn for each possible alias
* of @pdev at the root bus.
*/
int pci_for_each_dma_alias(struct pci_dev *pdev,
int (*fn)(struct pci_dev *pdev,
u16 alias, void *data), void *data)
{
struct pci_bus *bus;
int ret;
ret = fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn), data);
if (ret)
return ret;
/*
* If the device is broken and uses an alias requester ID for
* DMA, iterate over that too.
*/
if (unlikely(pdev->dma_alias_mask)) {
u8 devfn;
for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
data);
if (ret)
return ret;
}
}
for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
struct pci_dev *tmp;
/* Skip virtual buses */
if (!bus->self)
continue;
tmp = bus->self;
/*
* PCIe-to-PCI/X bridges alias transactions from downstream
* devices using the subordinate bus number (PCI Express to
* PCI/PCI-X Bridge Spec, rev 1.0, sec 2.3). For all cases
* where the upstream bus is PCI/X we alias to the bridge
* (there are various conditions in the previous reference
* where the bridge may take ownership of transactions, even
* when the secondary interface is PCI-X).
*/
if (pci_is_pcie(tmp)) {
switch (pci_pcie_type(tmp)) {
case PCI_EXP_TYPE_ROOT_PORT:
case PCI_EXP_TYPE_UPSTREAM:
case PCI_EXP_TYPE_DOWNSTREAM:
continue;
case PCI_EXP_TYPE_PCI_BRIDGE:
ret = fn(tmp,
PCI_DEVID(tmp->subordinate->number,
PCI_DEVFN(0, 0)), data);
if (ret)
return ret;
continue;
case PCI_EXP_TYPE_PCIE_BRIDGE:
ret = fn(tmp,
PCI_DEVID(tmp->bus->number,
tmp->devfn), data);
if (ret)
return ret;
continue;
}
} else {
if (tmp->dev_flags & PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS)
ret = fn(tmp,
PCI_DEVID(tmp->subordinate->number,
PCI_DEVFN(0, 0)), data);
else
ret = fn(tmp,
PCI_DEVID(tmp->bus->number,
tmp->devfn), data);
if (ret)
return ret;
}
}
return ret;
}
static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
{
struct pci_bus *child;
struct pci_bus *tmp;
if (bus->number == busnr)
return bus;
list_for_each_entry(tmp, &bus->children, node) {
child = pci_do_find_bus(tmp, busnr);
if (child)
return child;
}
return NULL;
}
/**
* pci_find_bus - locate PCI bus from a given domain and bus number
* @domain: number of PCI domain to search
* @busnr: number of desired PCI bus
*
* Given a PCI bus number and domain number, the desired PCI bus is located
* in the global list of PCI buses. If the bus is found, a pointer to its
* data structure is returned. If no bus is found, %NULL is returned.
*/
struct pci_bus *pci_find_bus(int domain, int busnr)
{
struct pci_bus *bus = NULL;
struct pci_bus *tmp_bus;
while ((bus = pci_find_next_bus(bus)) != NULL) {
if (pci_domain_nr(bus) != domain)
continue;
tmp_bus = pci_do_find_bus(bus, busnr);
if (tmp_bus)
return tmp_bus;
}
return NULL;
}
EXPORT_SYMBOL(pci_find_bus);
/**
* pci_find_next_bus - begin or continue searching for a PCI bus
* @from: Previous PCI bus found, or %NULL for new search.
*
* Iterates through the list of known PCI buses. A new search is
* initiated by passing %NULL as the @from argument. Otherwise if
* @from is not %NULL, searches continue from next device on the
* global list.
*/
struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
{
struct list_head *n;
struct pci_bus *b = NULL;
WARN_ON(in_interrupt());
down_read(&pci_bus_sem);
n = from ? from->node.next : pci_root_buses.next;
if (n != &pci_root_buses)
b = list_entry(n, struct pci_bus, node);
up_read(&pci_bus_sem);
return b;
}
EXPORT_SYMBOL(pci_find_next_bus);
/**
* pci_get_slot - locate PCI device for a given PCI slot
* @bus: PCI bus on which desired PCI device resides
* @devfn: encodes number of PCI slot in which the desired PCI
* device resides and the logical device number within that slot
* in case of multi-function devices.
*
* Given a PCI bus and slot/function number, the desired PCI device
* is located in the list of PCI devices.
* If the device is found, its reference count is increased and this
* function returns a pointer to its data structure. The caller must
* decrement the reference count by calling pci_dev_put().
* If no device is found, %NULL is returned.
*/
struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn)
{
struct pci_dev *dev;
WARN_ON(in_interrupt());
down_read(&pci_bus_sem);
list_for_each_entry(dev, &bus->devices, bus_list) {
if (dev->devfn == devfn)
goto out;
}
dev = NULL;
out:
pci_dev_get(dev);
up_read(&pci_bus_sem);
return dev;
}
EXPORT_SYMBOL(pci_get_slot);
/**
* pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot
* @domain: PCI domain/segment on which the PCI device resides.
* @bus: PCI bus on which desired PCI device resides
* @devfn: encodes number of PCI slot in which the desired PCI device
* resides and the logical device number within that slot in case of
* multi-function devices.
*
* Given a PCI domain, bus, and slot/function number, the desired PCI
* device is located in the list of PCI devices. If the device is
* found, its reference count is increased and this function returns a
* pointer to its data structure. The caller must decrement the
* reference count by calling pci_dev_put(). If no device is found,
* %NULL is returned.
*/
struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
unsigned int devfn)
{
struct pci_dev *dev = NULL;
for_each_pci_dev(dev) {
if (pci_domain_nr(dev->bus) == domain &&
(dev->bus->number == bus && dev->devfn == devfn))
return dev;
}
return NULL;
}
EXPORT_SYMBOL(pci_get_domain_bus_and_slot);
static int match_pci_dev_by_id(struct device *dev, void *data)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pci_device_id *id = data;
if (pci_match_one_device(id, pdev))
return 1;
return 0;
}
/*
* pci_get_dev_by_id - begin or continue searching for a PCI device by id
* @id: pointer to struct pci_device_id to match for the device
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is found
* with a matching id a pointer to its device structure is returned, and the
* reference count to the device is incremented. Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL as the @from argument. Otherwise
* if @from is not %NULL, searches continue from next device on the global
* list. The reference count for @from is always decremented if it is not
* %NULL.
*
* This is an internal function for use by the other search functions in
* this file.
*/
static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
struct pci_dev *from)
{
struct device *dev;
struct device *dev_start = NULL;
struct pci_dev *pdev = NULL;
WARN_ON(in_interrupt());
if (from)
dev_start = &from->dev;
dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
match_pci_dev_by_id);
if (dev)
pdev = to_pci_dev(dev);
pci_dev_put(from);
return pdev;
}
/**
* pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
* @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is found
* with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
* device structure is returned, and the reference count to the device is
* incremented. Otherwise, %NULL is returned. A new search is initiated by
* passing %NULL as the @from argument. Otherwise if @from is not %NULL,
* searches continue from next device on the global list.
* The reference count for @from is always decremented if it is not %NULL.
*/
struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
unsigned int ss_vendor, unsigned int ss_device,
struct pci_dev *from)
{
struct pci_device_id id = {
.vendor = vendor,
.device = device,
.subvendor = ss_vendor,
.subdevice = ss_device,
};
return pci_get_dev_by_id(&id, from);
}
EXPORT_SYMBOL(pci_get_subsys);
/**
* pci_get_device - begin or continue searching for a PCI device by vendor/device id
* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is
* found with a matching @vendor and @device, the reference count to the
* device is incremented and a pointer to its device structure is returned.
* Otherwise, %NULL is returned. A new search is initiated by passing %NULL
* as the @from argument. Otherwise if @from is not %NULL, searches continue
* from next device on the global list. The reference count for @from is
* always decremented if it is not %NULL.
*/
struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
struct pci_dev *from)
{
return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
}
EXPORT_SYMBOL(pci_get_device);
/**
* pci_get_class - begin or continue searching for a PCI device by class
* @class: search for a PCI device with this class designation
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is
* found with a matching @class, the reference count to the device is
* incremented and a pointer to its device structure is returned.
* Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL as the @from argument.
* Otherwise if @from is not %NULL, searches continue from next device
* on the global list. The reference count for @from is always decremented
* if it is not %NULL.
*/
struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
{
struct pci_device_id id = {
.vendor = PCI_ANY_ID,
.device = PCI_ANY_ID,
.subvendor = PCI_ANY_ID,
.subdevice = PCI_ANY_ID,
.class_mask = PCI_ANY_ID,
.class = class,
};
return pci_get_dev_by_id(&id, from);
}
EXPORT_SYMBOL(pci_get_class);
/**
* pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
* @ids: A pointer to a null terminated list of struct pci_device_id structures
* that describe the type of PCI device the caller is trying to find.
*
* Obvious fact: You do not have a reference to any device that might be found
* by this function, so if that device is removed from the system right after
* this function is finished, the value will be stale. Use this function to
* find devices that are usually built into a system, or for a general hint as
* to if another device happens to be present at this specific moment in time.
*/
int pci_dev_present(const struct pci_device_id *ids)
{
struct pci_dev *found = NULL;
WARN_ON(in_interrupt());
while (ids->vendor || ids->subvendor || ids->class_mask) {
found = pci_get_dev_by_id(ids, NULL);
if (found) {
pci_dev_put(found);
return 1;
}
ids++;
}
return 0;
}
EXPORT_SYMBOL(pci_dev_present);