设备PCI总线上有块FPGA,在没有加载代码前,不会被识别。
加载完代码后需要重新扫描PCI总线,识别到FPGA设备。
1. linux对pci rescan支持
注册总线pci_bus_type,关注成员dev_attr
static int __init pci_driver_init(void)
{
return bus_register(&pci_bus_type);
}
postcore_initcall(pci_driver_init);
struct bus_type pci_bus_type = {
.name = "pci",
.match = pci_bus_match,
.uevent = pci_uevent,
.probe = pci_device_probe,
.remove = pci_device_remove,
.shutdown = pci_device_shutdown,
.dev_attrs = pci_dev_attrs,
.bus_attrs = pci_bus_attrs,
.pm = PCI_PM_OPS_PTR,
};
pci_dev_attrs关注成员rescan
struct device_attribute pci_dev_attrs[] = {
__ATTR_RO(resource),
__ATTR_RO(vendor),
__ATTR_RO(device),
__ATTR_RO(subsystem_vendor),
__ATTR_RO(subsystem_device),
__ATTR_RO(class),
__ATTR_RO(irq),
__ATTR_RO(local_cpus),
__ATTR_RO(local_cpulist),
__ATTR_RO(modalias),
#ifdef CONFIG_NUMA
__ATTR_RO(numa_node),
#endif
__ATTR_RO(dma_mask_bits),
__ATTR_RO(consistent_dma_mask_bits),
__ATTR(enable, 0600, is_enabled_show, is_enabled_store),
__ATTR(broken_parity_status,(S_IRUGO|S_IWUSR),
broken_parity_status_show,broken_parity_status_store),
__ATTR(msi_bus, 0644, msi_bus_show, msi_bus_store),
#ifdef CONFIG_HOTPLUG
__ATTR(remove, (S_IWUSR|S_IWGRP), NULL, remove_store),
__ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, dev_rescan_store),
#endif
__ATTR_NULL,
};
rescan写操作对应处理函数
static ssize_t dev_rescan_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
unsigned long val;
struct pci_dev *pdev = to_pci_dev(dev);
if (strict_strtoul(buf, 0, &val) < 0)
return -EINVAL;
if (val) {
mutex_lock(&pci_remove_rescan_mutex);
pci_rescan_bus(pdev->bus);
mutex_unlock(&pci_remove_rescan_mutex);
}
return count;
}
重新扫描选定PCI总线,配置新设备和向系统添加新设备
unsigned int __ref pci_rescan_bus(struct pci_bus *bus)
{
unsigned int max;
struct pci_dev *dev;
max = pci_scan_child_bus(bus);
down_read(&pci_bus_sem);
list_for_each_entry(dev, &bus->devices, bus_list)
if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
if (dev->subordinate)
pci_bus_size_bridges(dev->subordinate);
up_read(&pci_bus_sem);
pci_bus_assign_resources(bus);
pci_enable_bridges(bus);
pci_bus_add_devices(bus);
return max;
}
EXPORT_SYMBOL_GPL(pci_rescan_bus);
2. 应用
echo 1 > /sys/bus/pci/devices/0000:00:1e.0/rescan