在drivers/pci/probe.c中的pci_init_capabilities中会调用pci_ea_init 来初始化Enhanced Allocation。
void pci_ea_init(struct pci_dev *dev)
{
int ea;
u8 num_ent;
int offset;
int i;
/* find PCI EA capability in list */
ea = pci_find_capability(dev, PCI_CAP_ID_EA);
if (!ea)
return;
/* determine the number of entries */
pci_bus_read_config_byte(dev->bus, dev->devfn, ea + PCI_EA_NUM_ENT,
&num_ent);
num_ent &= PCI_EA_NUM_ENT_MASK;
offset = ea + PCI_EA_FIRST_ENT;
/* Skip DWORD 2 for type 1 functions */
if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
offset += 4;
/* parse each EA entry */
for (i = 0; i < num_ent; ++i)
offset = pci_ea_read(dev, offset);
}
在pci_ea_init中先通过pci_find_capability 判断当前设备是否支持PCI_CAP_ID_EA。如果支持的话，在通过PCI_EA_NUM_ENT 读取当前支持多少个EA entry。最后在for循环中通过pci_ea_read来将ea的resource添加到device中
static int pci_ea_read(struct pci_dev *dev, int offset)
{
struct resource *res;
int ent_size, ent_offset = offset;
resource_size_t start, end;
unsigned long flags;
u32 dw0, bei, base, max_offset;
u8 prop;
//通过long是否是8byte 来决定当前系统是否是64bit
bool support_64 = (sizeof(resource_size_t) >= 8);
pci_read_config_dword(dev, ent_offset, &dw0);
ent_offset += 4;
/* Entry size field indicates DWORDs after 1st */
ent_size = ((dw0 & PCI_EA_ES) + 1) << 2;
if (!(dw0 & PCI_EA_ENABLE)) /* Entry not enabled */
goto out;
bei = (dw0 & PCI_EA_BEI) >> 4;
prop = (dw0 & PCI_EA_PP) >> 8;
/*
* If the Property is in the reserved range, try the Secondary
* Property instead.
*/
if (prop > PCI_EA_P_BRIDGE_IO && prop < PCI_EA_P_MEM_RESERVED)
prop = (dw0 & PCI_EA_SP) >> 16;
if (prop > PCI_EA_P_BRIDGE_IO)
goto out;
//得到res的指针struct resource *res;
res = pci_ea_get_resource(dev, bei, prop);
if (!res) {
dev_err(&dev->dev, "Unsupported EA entry BEI: %u\n", bei);
goto out;
}
flags = pci_ea_flags(dev, prop);
if (!flags) {
dev_err(&dev->dev, "Unsupported EA properties: %#x\n", prop);
goto out;
}
/* Read Base */
pci_read_config_dword(dev, ent_offset, &base);
start = (base & PCI_EA_FIELD_MASK);
ent_offset += 4;
/* Read MaxOffset */
pci_read_config_dword(dev, ent_offset, &max_offset);
ent_offset += 4;
/* Read Base MSBs (if 64-bit entry) */
if (base & PCI_EA_IS_64) {
u32 base_upper;
pci_read_config_dword(dev, ent_offset, &base_upper);
ent_offset += 4;
flags |= IORESOURCE_MEM_64;
/* entry starts above 32-bit boundary, can't use */
if (!support_64 && base_upper)
goto out;
if (support_64)
start |= ((u64)base_upper << 32);
}
end = start + (max_offset | 0x03);
/* Read MaxOffset MSBs (if 64-bit entry) */
if (max_offset & PCI_EA_IS_64) {
u32 max_offset_upper;
pci_read_config_dword(dev, ent_offset, &max_offset_upper);
ent_offset += 4;
flags |= IORESOURCE_MEM_64;
/* entry too big, can't use */
if (!support_64 && max_offset_upper)
goto out;
if (support_64)
end += ((u64)max_offset_upper << 32);
}
if (end < start) {
dev_err(&dev->dev, "EA Entry crosses address boundary\n");
goto out;
}
if (ent_size != ent_offset - offset) {
dev_err(&dev->dev,
"EA Entry Size (%d) does not match length read (%d)\n",
ent_size, ent_offset - offset);
goto out;
}
// 更新resource的值
res->name = pci_name(dev);
res->start = start;
res->end = end;
res->flags = flags;
if (bei <= PCI_EA_BEI_BAR5)
dev_printk(KERN_DEBUG, &dev->dev, "BAR %d: %pR (from Enhanced Allocation, properties %#02x)\n",
bei, res, prop);
else if (bei == PCI_EA_BEI_ROM)
dev_printk(KERN_DEBUG, &dev->dev, "ROM: %pR (from Enhanced Allocation, properties %#02x)\n",
res, prop);
else if (bei >= PCI_EA_BEI_VF_BAR0 && bei <= PCI_EA_BEI_VF_BAR5)
dev_printk(KERN_DEBUG, &dev->dev, "VF BAR %d: %pR (from Enhanced Allocation, properties %#02x)\n",
bei - PCI_EA_BEI_VF_BAR0, res, prop);
else
dev_printk(KERN_DEBUG, &dev->dev, "BEI %d res: %pR (from Enhanced Allocation, properties %#02x)\n",
bei, res, prop);
out:
return offset + ent_size;
}
从pci_ea_get_resource 中可以看到ea的resource 分为三类，
第一类是在bei<=PCI_EA_BEI_BAR5和prop <= PCI_EA_P_IO之间
第二类属于PCI_IOV是在bei >= PCI_EA_BEI_VF_BAR0 && bei <= PCI_EA_BEI_VF_BAR5 &&
(prop == PCI_EA_P_VF_MEM || prop == PCI_EA_P_VF_MEM_PREFETCH)
第三类bei == PCI_EA_BEI_ROM
static struct resource *pci_ea_get_resource(struct pci_dev *dev, u8 bei,
u8 prop)
{
if (bei <= PCI_EA_BEI_BAR5 && prop <= PCI_EA_P_IO)
return &dev->resource[bei];
#ifdef CONFIG_PCI_IOV
else if (bei >= PCI_EA_BEI_VF_BAR0 && bei <= PCI_EA_BEI_VF_BAR5 &&
(prop == PCI_EA_P_VF_MEM || prop == PCI_EA_P_VF_MEM_PREFETCH))
return &dev->resource[PCI_IOV_RESOURCES +
bei - PCI_EA_BEI_VF_BAR0];
#endif
else if (bei == PCI_EA_BEI_ROM)
return &dev->resource[PCI_ROM_RESOURCE];
else
return NULL;
}
这三类从pci_ea_read 中最后的打印log中也可以看到.
总结一下，ea就是给dev的resouce 赋值，这些resource可以分为3类.且可以分为32bit和64bit。这些信息可以从开机log中看到
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