pci设备的初始化
这里讨论系统上电时的情况, 热插拔的情况应该差不多. 首先是从根总线开始, 然后就是扫描这个根总线上的每一条子BUS, 如下: unsigned int pci_scan_child_bus(struct pci_bus *bus) { unsigned int devfn, pass, max = bus->secondary; struct pci_dev *dev; pr_debug("PCI: Scanning bus x:x\n", pci_domain_nr(bus), bus->number); 这里循环256(0x100)/8 = 32次的意思是, 每个总线可能有32个设备, 而每个设备可能是多功能的, 且最多有8个功能. for (devfn = 0; devfn < 0x100; devfn += 8) pci_scan_slot(bus, devfn); //下面在递归扫描PCI桥,不是我们要关心的. pr_debug("PCI: Fixups for bus x:x\n", pci_domain_nr(bus), bus->number); pcibios_fixup_bus(bus); for (pass=0; pass < 2; pass++) list_for_each_entry(dev, &bus->devices, bus_list) { if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE || dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) max = pci_scan_bridge(bus, dev, max, pass); } pr_debug("PCI: Bus scan for x:x returning with max=x\n", pci_domain_nr(bus), bus->number, max); return max; } int pci_scan_slot(struct pci_bus *bus, int devfn) { int func, nr = 0; int scan_all_fns; //空函数 scan_all_fns = pcibios_scan_all_fns(bus, devfn); //每个设备可能有8个功能 for (func = 0; func < 8; func++, devfn++) { struct pci_dev *dev; //分配并初始化找到的设备 dev = pci_scan_single_device(bus, devfn); if (dev) { nr++; if (!dev->multifunction) { if (func > 0) { dev->multifunction = 1; } else { break; } } } else { if (func == 0 && !scan_all_fns) break; } } return nr; } struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn) { struct pci_dev *dev; //扫描设备, 如果存在, 分配一个结构, //并读取这个设备的寄存器信息将其初始化 dev = pci_scan_device(bus, devfn); if (!dev) return NULL; //将设备加入的bus总线 pci_device_add(dev, bus); return dev; } 这个函数的功能上面的注释已经说明白了 static struct pci_dev * __devinit pci_scan_device(struct pci_bus *bus, int devfn) { struct pci_dev *dev; u32 l; u8 hdr_type; int delay = 1; //两个检查 if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, &l)) return NULL; if (l == 0xffffffff || l == 0x00000000 || l == 0x0000ffff || l == 0xffff0000) return NULL; while (l == 0xffff0001) { msleep(delay); delay *= 2; if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, &l)) return NULL; if (delay > 60 * 1000) { printk(KERN_WARNING "Device x:x:x.%d not " "responding\n", pci_domain_nr(bus), bus->number, PCI_SLOT(devfn), PCI_FUNC(devfn)); return NULL; } } //读PCI类型信息, PCI_HEADER_TYPE是在这个寄存器中的偏移值 //可能的类型信息如下: #define PCI_HEADER_TYPE 0x0e #define PCI_HEADER_TYPE_NORMAL 0 #define PCI_HEADER_TYPE_BRIDGE 1 #define PCI_HEADER_TYPE_CARDBUS 2 if (pci_bus_read_config_byte(bus, devfn, PCI_HEADER_TYPE, &hdr_type)) return NULL; //如果上面的成功了, 则为设备分配一个pci_dev结构, //我们在写驱动的时候看到, 在调用probe函数是, 参数传入的就是这里得到的结构. //这个结构在这个函数里面已经初始化好了. dev = alloc_pci_dev(); if (!dev) return NULL; //初步初始化一些域 dev->bus = bus; dev->sysdata = bus->sysdata; dev->dev.parent = bus->bridge; dev->dev.bus = &pci_bus_type; dev->devfn = devfn; dev->hdr_type = hdr_type & 0x7f; dev->multifunction = !!(hdr_type & 0x80); dev->vendor = l & 0xffff; dev->device = (l >> 16) & 0xffff; dev->cfg_size = pci_cfg_space_size(dev); // 用于PCI-X dev->error_state = pci_channel_io_normal; dev->dma_mask = 0xffffffff; //32为DMA //进一步初始化, 数据来自于寄存器 if (pci_setup_device(dev) < 0) { kfree(dev); return NULL; } return dev; } //分配一个结构并初始化两个队列 struct pci_dev *alloc_pci_dev(void) { struct pci_dev *dev; dev = kzalloc(sizeof(struct pci_dev), GFP_KERNEL); if (!dev) return NULL; INIT_LIST_HEAD(&dev->global_list); INIT_LIST_HEAD(&dev->bus_list); pci_msi_init_pci_dev(dev); return dev; } struct bus_type pci_bus_type = { .name = "pci", .match = pci_bus_match, .uevent = pci_uevent, .probe = pci_device_probe, .remove = pci_device_remove, .suspend = pci_device_suspend, .suspend_late = pci_device_suspend_late, .resume_early = pci_device_resume_early, .resume = pci_device_resume, .shutdown = pci_device_shutdown, .dev_attrs = pci_dev_attrs, }; 这个函数比较简单, 可以看注释,就不说了 static int pci_setup_device(struct pci_dev * dev) { u32 class; sprintf(pci_name(dev), "x:x:x.%d", pci_domain_nr(dev->bus), dev->bus->number, PCI_SLOT(dev->devfn), PCI_FUNC(dev->devfn)); pci_read_config_dword(dev, PCI_CLASS_REVISION, &class); class >>= 8; dev->class = class; class >>= 8; pr_debug("PCI: Found %s [x/x] x x\n", pci_name(dev), dev->vendor, dev->device, class, dev->hdr_type); dev->current_state = PCI_UNKNOWN; pci_fixup_device(pci_fixup_early, dev); class = dev->class >> 8; switch (dev->hdr_type) { case PCI_HEADER_TYPE_NORMAL: if (class == PCI_CLASS_BRIDGE_PCI) goto bad; pci_read_irq(dev); pci_read_bases(dev, 6, PCI_ROM_ADDRESS); pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor); pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device); if (class == PCI_CLASS_STORAGE_IDE) { u8 progif; pci_read_config_byte(dev, PCI_CLASS_PROG, &progif); if ((progif & 1) == 0) { dev->resource[0].start = 0x1F0; dev->resource[0].end = 0x1F7; dev->resource[0].flags = LEGACY_IO_RESOURCE; dev->resource[1].start = 0x3F6; dev->resource[1].end = 0x3F6; dev->resource[1].flags = LEGACY_IO_RESOURCE; } if ((progif & 4) == 0) { dev->resource[2].start = 0x170; dev->resource[2].end = 0x177; dev->resource[2].flags = LEGACY_IO_RESOURCE; dev->resource[3].start = 0x376; dev->resource[3].end = 0x376; dev->resource[3].flags = LEGACY_IO_RESOURCE; } } break; case PCI_HEADER_TYPE_BRIDGE: if (class != PCI_CLASS_BRIDGE_PCI) goto bad; pci_read_irq(dev); dev->transparent = ((dev->class & 0xff) == 1); pci_read_bases(dev, 2, PCI_ROM_ADDRESS1); break; case PCI_HEADER_TYPE_CARDBUS: if (class != PCI_CLASS_BRIDGE_CARDBUS) goto bad; pci_read_irq(dev); pci_read_bases(dev, 1, 0); pci_read_config_word(dev, PCI_CB_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor); pci_read_config_word(dev, PCI_CB_SUBSYSTEM_ID, &dev->subsystem_device); break; default: printk(KERN_ERR "PCI: device %s has unknown header type x, ignoring.\n", pci_name(dev), dev->hdr_type); return -1; bad: printk(KERN_ERR "PCI: %s: class %x doesn't match header type x. Ignoring class.\n", pci_name(dev), class, dev->hdr_type); dev->class = PCI_CLASS_NOT_DEFINED; } return 0; } 设备初始化完成后, 我们就回到了pci_scan_single_device()这个函数, 下一步就是将这个分配好的设备加入的bus队列中去了. void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) { device_initialize(&dev->dev); dev->dev.release = pci_release_dev; pci_dev_get(dev); set_dev_node(&dev->dev, pcibus_to_node(bus)); dev->dev.dma_mask = &dev->dma_mask; dev->dev.coherent_dma_mask = 0xffffffffull; pci_fixup_device(pci_fixup_header, dev); INIT_LIST_HEAD(&dev->global_list); down_write(&pci_bus_sem); list_add_tail(&dev->bus_list, &bus->devices); //加入到bus的device队列 up_write(&pci_bus_sem); } void device_initialize(struct device *dev) { //属于devices_subsys子系统 kobj_set_kset_s(dev, devices_subsys); //以下是初始化一下队列, 如等待队列 kobject_init(&dev->kobj); klist_init(&dev->klist_children, klist_children_get, klist_children_put); INIT_LIST_HEAD(&dev->dma_pools); INIT_LIST_HEAD(&dev->node); init_MUTEX(&dev->sem); spin_lock_init(&dev->devres_lock); INIT_LIST_HEAD(&dev->devres_head); device_init_wakeup(dev, 0); set_dev_node(dev, -1); }
