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提交 3e466e2d 编写于 作者: B Bjorn Helgaas
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PCI: Tidy up pci/probe.c comments 

No functional change intended.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
上级 1291a0d5
隐藏空白更改
内联 并排
Showing with 116 addition and 89 deletion
drivers/pci/probe.c
浏览文件 @ 3e466e2d
......@@ -69,8 +69,8 @@ static int find_anything(struct device *dev, void *data)
}
/*
* Some device drivers need know if pci is initiated.
* Basically, we think pci is not initiated when there
* Some device drivers need know if PCI is initiated.
* Basically, we think PCI is not initiated when there
* is no device to be found on the pci_bus_type.
*/
int no_pci_devices(void)
......@@ -116,12 +116,16 @@ static u64 pci_size(u64 base, u64 maxbase, u64 mask)
if (!size)
return 0;
/* Get the lowest of them to find the decode size, and
from that the extent. */
/*
* Get the lowest of them to find the decode size, and from that
* the extent.
*/
size = (size & ~(size-1)) - 1;
/* base == maxbase can be valid only if the BAR has
already been programmed with all 1s. */
/*
* base == maxbase can be valid only if the BAR has already been
* programmed with all 1s.
*/
if (base == maxbase && ((base | size) & mask) != mask)
return 0;
......@@ -164,7 +168,7 @@ static inline unsigned long decode_bar(struct pci_dev *dev, u32 bar)
#define PCI_COMMAND_DECODE_ENABLE (PCI_COMMAND_MEMORY | PCI_COMMAND_IO)
/**
* pci_read_base - read a PCI BAR
* pci_read_base - Read a PCI BAR
* @dev: the PCI device
* @type: type of the BAR
* @res: resource buffer to be filled in
......@@ -764,7 +768,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
bridge->bus = bus;
/* temporarily move resources off the list */
/* Temporarily move resources off the list */
list_splice_init(&bridge->windows, &resources);
bus->sysdata = bridge->sysdata;
bus->msi = bridge->msi;
......@@ -776,7 +780,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);
if (b) {
/* If we already got to this bus through a different bridge, ignore it */
/* Ignore it if we already got here via a different bridge */
dev_dbg(&b->dev, "bus already known\n");
err = -EEXIST;
goto free;
......@@ -869,9 +873,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
int i;
int ret;
/*
* Allocate a new bus, and inherit stuff from the parent..
*/
/* Allocate a new bus and inherit stuff from the parent */
child = pci_alloc_bus(parent);
if (!child)
return NULL;
......@@ -882,16 +884,14 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
child->sysdata = parent->sysdata;
child->bus_flags = parent->bus_flags;
/* initialize some portions of the bus device, but don't register it
* now as the parent is not properly set up yet.
/*
* Initialize some portions of the bus device, but don't register
* it now as the parent is not properly set up yet.
*/
child->dev.class = &pcibus_class;
dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
/*
* Set up the primary, secondary and subordinate
* bus numbers.
*/
/* Set up the primary, secondary and subordinate bus numbers */
child->number = child->busn_res.start = busnr;
child->primary = parent->busn_res.start;
child->busn_res.end = 0xff;
......@@ -907,7 +907,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
pci_set_bus_of_node(child);
pci_set_bus_speed(child);
/* Set up default resource pointers and names.. */
/* Set up default resource pointers and names */
for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) {
child->resource[i] = &bridge->resource[PCI_BRIDGE_RESOURCES+i];
child->resource[i]->name = child->name;
......@@ -1022,8 +1022,10 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
broken = 1;
}
/* Disable MasterAbortMode during probing to avoid reporting
of bus errors (in some architectures) */
/*
* Disable Master-Abort Mode during probing to avoid reporting of
* bus errors in some architectures.
*/
pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &bctl);
pci_write_config_word(dev, PCI_BRIDGE_CONTROL,
bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT);
......@@ -1033,18 +1035,19 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
!is_cardbus && !broken) {
unsigned int cmax;
/*
* Bus already configured by firmware, process it in the first
* pass and just note the configuration.
* Bus already configured by firmware, process it in the
* first pass and just note the configuration.
*/
if (pass)
goto out;
/*
* The bus might already exist for two reasons: Either we are
* rescanning the bus or the bus is reachable through more than
* one bridge. The second case can happen with the i450NX
* chipset.
* The bus might already exist for two reasons: Either we
* are rescanning the bus or the bus is reachable through
* more than one bridge. The second case can happen with
* the i450NX chipset.
*/
child = pci_find_bus(pci_domain_nr(bus), secondary);
if (!child) {
......@@ -1060,22 +1063,27 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
if (cmax > subordinate)
dev_warn(&dev->dev, "bridge has subordinate %02x but max busn %02x\n",
subordinate, cmax);
/* subordinate should equal child->busn_res.end */
/* Subordinate should equal child->busn_res.end */
if (subordinate > max)
max = subordinate;
} else {
/*
* We need to assign a number to this bus which we always
* do in the second pass.
*/
if (!pass) {
if (pcibios_assign_all_busses() || broken || is_cardbus)
/* Temporarily disable forwarding of the
configuration cycles on all bridges in
this bus segment to avoid possible
conflicts in the second pass between two
bridges programmed with overlapping
bus ranges. */
/*
* Temporarily disable forwarding of the
* configuration cycles on all bridges in
* this bus segment to avoid possible
* conflicts in the second pass between two
* bridges programmed with overlapping bus
* ranges.
*/
pci_write_config_dword(dev, PCI_PRIMARY_BUS,
buses & ~0xffffff);
goto out;
......@@ -1084,9 +1092,11 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
/* Clear errors */
pci_write_config_word(dev, PCI_STATUS, 0xffff);
/* Prevent assigning a bus number that already exists.
* This can happen when a bridge is hot-plugged, so in
* this case we only re-scan this bus. */
/*
* Prevent assigning a bus number that already exists.
* This can happen when a bridge is hot-plugged, so in this
* case we only re-scan this bus.
*/
child = pci_find_bus(pci_domain_nr(bus), max+1);
if (!child) {
child = pci_add_new_bus(bus, dev, max+1);
......@@ -1113,19 +1123,18 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
buses |= CARDBUS_LATENCY_TIMER << 24;
}
/*
* We need to blast all three values with a single write.
*/
/* We need to blast all three values with a single write */
pci_write_config_dword(dev, PCI_PRIMARY_BUS, buses);
if (!is_cardbus) {
child->bridge_ctl = bctl;
max = pci_scan_child_bus_extend(child, available_buses);
} else {
/*
* For CardBus bridges, we leave 4 bus numbers
* as cards with a PCI-to-PCI bridge can be
* inserted later.
* For CardBus bridges, we leave 4 bus numbers as
* cards with a PCI-to-PCI bridge can be inserted
* later.
*/
for (i = 0; i < CARDBUS_RESERVE_BUSNR; i++) {
struct pci_bus *parent = bus;
......@@ -1141,10 +1150,11 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
parent = parent->parent;
}
if (j) {
/*
* Often, there are two cardbus bridges
* -- try to leave one valid bus number
* for each one.
* Often, there are two CardBus
* bridges -- try to leave one
* valid bus number for each one.
*/
i /= 2;
break;
......@@ -1152,9 +1162,8 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
}
max += i;
}
/*
* Set the subordinate bus number to its real value.
*/
/* Set subordinate bus number to its real value */
pci_bus_update_busn_res_end(child, max);
pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
}
......@@ -1295,7 +1304,7 @@ static void set_pcie_thunderbolt(struct pci_dev *dev)
}
/**
* pci_ext_cfg_is_aliased - is ext config space just an alias of std config?
* pci_ext_cfg_is_aliased - Is ext config space just an alias of std config?
* @dev: PCI device
*
* PCI Express to PCI/PCI-X Bridge Specification, rev 1.0, 4.1.4 says that
......@@ -1332,7 +1341,7 @@ static bool pci_ext_cfg_is_aliased(struct pci_dev *dev)
}
/**
* pci_cfg_space_size - get the configuration space size of the PCI device.
* pci_cfg_space_size - Get the configuration space size of the PCI device
* @dev: PCI device
*
* Regular PCI devices have 256 bytes, but PCI-X 2 and PCI Express devices
......@@ -1398,7 +1407,7 @@ static void pci_msi_setup_pci_dev(struct pci_dev *dev)
}
/**
* pci_intx_mask_broken - test PCI_COMMAND_INTX_DISABLE writability
* pci_intx_mask_broken - Test PCI_COMMAND_INTX_DISABLE writability
* @dev: PCI device
*
* Test whether PCI_COMMAND_INTX_DISABLE is writable for @dev. Check this
......@@ -1426,11 +1435,11 @@ static int pci_intx_mask_broken(struct pci_dev *dev)
}
/**
* pci_setup_device - fill in class and map information of a device
* pci_setup_device - Fill in class and map information of a device
* @dev: the device structure to fill
*
* Initialize the device structure with information about the device's
* vendor,class,memory and IO-space addresses,IRQ lines etc.
* vendor,class,memory and IO-space addresses, IRQ lines etc.
* Called at initialisation of the PCI subsystem and by CardBus services.
* Returns 0 on success and negative if unknown type of device (not normal,
* bridge or CardBus).
......@@ -1456,8 +1465,11 @@ int pci_setup_device(struct pci_dev *dev)
set_pcie_port_type(dev);
pci_dev_assign_slot(dev);
/* Assume 32-bit PCI; let 64-bit PCI cards (which are far rarer)
set this higher, assuming the system even supports it. */
/*
* Assume 32-bit PCI; let 64-bit PCI cards (which are far rarer)
* set this higher, assuming the system even supports it.
*/
dev->dma_mask = 0xffffffff;
dev_set_name(&dev->dev, "%04x:%02x:%02x.%d", pci_domain_nr(dev->bus),
......@@ -1471,10 +1483,10 @@ int pci_setup_device(struct pci_dev *dev)
dev_printk(KERN_DEBUG, &dev->dev, "[%04x:%04x] type %02x class %#08x\n",
dev->vendor, dev->device, dev->hdr_type, dev->class);
/* need to have dev->class ready */
/* Need to have dev->class ready */
dev->cfg_size = pci_cfg_space_size(dev);
/* need to have dev->cfg_size ready */
/* Need to have dev->cfg_size ready */
set_pcie_thunderbolt(dev);
/* "Unknown power state" */
......@@ -1482,7 +1494,8 @@ int pci_setup_device(struct pci_dev *dev)
/* Early fixups, before probing the BARs */
pci_fixup_device(pci_fixup_early, dev);
/* device class may be changed after fixup */
/* Device class may be changed after fixup */
class = dev->class >> 8;
if (dev->non_compliant_bars) {
......@@ -1553,9 +1566,12 @@ int pci_setup_device(struct pci_dev *dev)
case PCI_HEADER_TYPE_BRIDGE: /* bridge header */
if (class != PCI_CLASS_BRIDGE_PCI)
goto bad;
/* The PCI-to-PCI bridge spec requires that subtractive
decoding (i.e. transparent) bridge must have programming
interface code of 0x01. */
/*
* The PCI-to-PCI bridge spec requires that subtractive
* decoding (i.e. transparent) bridge must have programming
* interface code of 0x01.
*/
pci_read_irq(dev);
dev->transparent = ((dev->class & 0xff) == 1);
pci_read_bases(dev, 2, PCI_ROM_ADDRESS1);
......@@ -1772,6 +1788,7 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
/* Initialize Advanced Error Capabilities and Control Register */
pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
reg32 = (reg32 & hpp->adv_err_cap_and) | hpp->adv_err_cap_or;
/* Don't enable ECRC generation or checking if unsupported */
if (!(reg32 & PCI_ERR_CAP_ECRC_GENC))
reg32 &= ~PCI_ERR_CAP_ECRC_GENE;
......@@ -1902,10 +1919,11 @@ static void pci_release_capabilities(struct pci_dev *dev)
}
/**
* pci_release_dev - free a pci device structure when all users of it are finished.
* pci_release_dev - Free a PCI device structure when all users of it are
* finished
* @dev: device that's been disconnected
*
* Will be called only by the device core when all users of this pci device are
* Will be called only by the device core when all users of this PCI device are
* done.
*/
static void pci_release_dev(struct device *dev)
......@@ -1993,7 +2011,7 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
return false;
/* some broken boards return 0 or ~0 if a slot is empty: */
/* Some broken boards return 0 or ~0 if a slot is empty: */
if (*l == 0xffffffff || *l == 0x00000000 ||
*l == 0x0000ffff || *l == 0xffff0000)
return false;
......@@ -2006,8 +2024,8 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);
/*
* Read the config data for a PCI device, sanity-check it
* and fill in the dev structure...
* Read the config data for a PCI device, sanity-check it,
* and fill in the dev structure.
*/
static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
{
......@@ -2073,7 +2091,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
}
/*
* This is the equivalent of pci_host_bridge_msi_domain that acts on
* This is the equivalent of pci_host_bridge_msi_domain() that acts on
* devices. Firmware interfaces that can select the MSI domain on a
* per-device basis should be called from here.
*/
......@@ -2082,7 +2100,7 @@ static struct irq_domain *pci_dev_msi_domain(struct pci_dev *dev)
struct irq_domain *d;
/*
* If a domain has been set through the pcibios_add_device
* If a domain has been set through the pcibios_add_device()
* callback, then this is the one (platform code knows best).
*/
d = dev_get_msi_domain(&dev->dev);
......@@ -2136,10 +2154,10 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
/* Fix up broken headers */
pci_fixup_device(pci_fixup_header, dev);
/* moved out from quirk header fixup code */
/* Moved out from quirk header fixup code */
pci_reassigndev_resource_alignment(dev);
/* Clear the state_saved flag. */
/* Clear the state_saved flag */
dev->state_saved = false;
/* Initialize various capabilities */
......@@ -2156,7 +2174,7 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
ret = pcibios_add_device(dev);
WARN_ON(ret < 0);
/* Setup MSI irq domain */
/* Set up MSI IRQ domain */
pci_set_msi_domain(dev);
/* Notifier could use PCI capabilities */
......@@ -2235,9 +2253,9 @@ static int only_one_child(struct pci_bus *bus)
}
/**
* pci_scan_slot - scan a PCI slot on a bus for devices.
* pci_scan_slot - Scan a PCI slot on a bus for devices
* @bus: PCI bus to scan
* @devfn: slot number to scan (must have zero function.)
* @devfn: slot number to scan (must have zero function)
*
* Scan a PCI slot on the specified PCI bus for devices, adding
* discovered devices to the @bus->devices list. New devices
......@@ -2268,7 +2286,7 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
}
}
/* only one slot has pcie device */
/* Only one slot has PCIe device */
if (bus->self && nr)
pcie_aspm_init_link_state(bus->self);
......@@ -2317,7 +2335,9 @@ static void pcie_write_mps(struct pci_dev *dev, int mps)
if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT &&
dev->bus->self)
/* For "Performance", the assumption is made that
/*
* For "Performance", the assumption is made that
* downstream communication will never be larger than
* the MRRS. So, the MPS only needs to be configured
* for the upstream communication. This being the case,
......@@ -2341,20 +2361,23 @@ static void pcie_write_mrrs(struct pci_dev *dev)
{
int rc, mrrs;
/* In the "safe" case, do not configure the MRRS. There appear to be
/*
* In the "safe" case, do not configure the MRRS. There appear to be
* issues with setting MRRS to 0 on a number of devices.
*/
if (pcie_bus_config != PCIE_BUS_PERFORMANCE)
return;
/* For Max performance, the MRRS must be set to the largest supported
/*
* For max performance, the MRRS must be set to the largest supported
* value. However, it cannot be configured larger than the MPS the
* device or the bus can support. This should already be properly
* configured by a prior call to pcie_write_mps.
* configured by a prior call to pcie_write_mps().
*/
mrrs = pcie_get_mps(dev);
/* MRRS is a R/W register. Invalid values can be written, but a
/*
* MRRS is a R/W register. Invalid values can be written, but a
* subsequent read will verify if the value is acceptable or not.
* If the MRRS value provided is not acceptable (e.g., too large),
* shrink the value until it is acceptable to the HW.
......@@ -2396,7 +2419,8 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
return 0;
}
/* pcie_bus_configure_settings requires that pci_walk_bus work in a top-down,
/*
* pcie_bus_configure_settings() requires that pci_walk_bus work in a top-down,
* parents then children fashion. If this changes, then this code will not
* work as designed.
*/
......@@ -2410,7 +2434,8 @@ void pcie_bus_configure_settings(struct pci_bus *bus)
if (!pci_is_pcie(bus->self))
return;
/* FIXME - Peer to peer DMA is possible, though the endpoint would need
/*
* FIXME - Peer to peer DMA is possible, though the endpoint would need
* to be aware of the MPS of the destination. To work around this,
* simply force the MPS of the entire system to the smallest possible.
*/
......@@ -2464,7 +2489,7 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
for (devfn = 0; devfn < 0x100; devfn += 8)
pci_scan_slot(bus, devfn);
/* Reserve buses for SR-IOV capability. */
/* Reserve buses for SR-IOV capability */
used_buses = pci_iov_bus_range(bus);
max += used_buses;
......@@ -2506,6 +2531,7 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
unsigned int buses = 0;
if (!hotplug_bridges && normal_bridges == 1) {
/*
* There is only one bridge on the bus (upstream
* port) so it gets all available buses which it
......@@ -2514,6 +2540,7 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
*/
buses = available_buses;
} else if (dev->is_hotplug_bridge) {
/*
* Distribute the extra buses between hotplug
* bridges if any.
......@@ -2572,8 +2599,8 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
EXPORT_SYMBOL_GPL(pci_scan_child_bus);
/**
* pcibios_root_bridge_prepare - Platform-specific host bridge setup.
* @bridge: Host bridge to set up.
* pcibios_root_bridge_prepare - Platform-specific host bridge setup
* @bridge: Host bridge to set up
*
* Default empty implementation. Replace with an architecture-specific setup
* routine, if necessary.
......@@ -2776,7 +2803,7 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
EXPORT_SYMBOL(pci_scan_bus);
/**
* pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
* pci_rescan_bus_bridge_resize - Scan a PCI bus for devices
* @bridge: PCI bridge for the bus to scan
*
* Scan a PCI bus and child buses for new devices, add them,
......@@ -2801,11 +2828,11 @@ unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
}
/**
* pci_rescan_bus - scan a PCI bus for devices.
* pci_rescan_bus - Scan a PCI bus for devices
* @bus: PCI bus to scan
*
* Scan a PCI bus and child buses for new devices, adds them,
* and enables them.
* Scan a PCI bus and child buses for new devices, add them,
* and enable them.
*
* Returns the max number of subordinate bus discovered.
*/
......
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