Linux Kernel设备驱动模型之 struct device

设备模型之设备描述：

/**
 * struct device - The basic device structure
 * @parent: The device's "parent" device, the device to which it is attached.
 *   In most cases, a parent device is some sort of bus or host
 *   controller. If parent is NULL, the device, is a top-level device,
 *   which is not usually what you want.
 * @p:  Holds the private data of the driver core portions of the device.
 *   See the comment of the struct device_private for detail.
 * @kobj: A top-level, abstract class from which other classes are derived.
 * @init_name: Initial name of the device.
 * @type: The type of device.
 *   This identifies the device type and carries type-specific
 *   information.
 * @mutex: Mutex to synchronize calls to its driver.
 * @bus: Type of bus device is on.
 * @driver: Which driver has allocated this
 * @platform_data: Platform data specific to the device.
 *   Example: For devices on custom boards, as typical of embedded
 *   and SOC based hardware, Linux often uses platform_data to point
 *   to board-specific structures describing devices and how they
 *   are wired.  That can include what ports are available, chip
 *   variants, which GPIO pins act in what additional roles, and so
 *   on.  This shrinks the "Board Support Packages" (BSPs) and
 *   minimizes board-specific #ifdefs in drivers.
 * @driver_data: Private pointer for driver specific info.
 * @power: For device power management.
 *   See Documentation/power/devices.txt for details.
 * @pm_domain: Provide callbacks that are executed during system suspend,
 *   hibernation, system resume and during runtime PM transitions
 *   along with subsystem-level and driver-level callbacks.
 * @pins: For device pin management.
 *  See Documentation/pinctrl.txt for details.
 * @msi_list: Hosts MSI descriptors
 * @msi_domain: The generic MSI domain this device is using.
 * @numa_node: NUMA node this device is close to.
 * @dma_mask: Dma mask (if dma'ble device).
 * @coherent_dma_mask: Like dma_mask, but for alloc_coherent mapping as not all
 *   hardware supports 64-bit addresses for consistent allocations
 *   such descriptors.
 * @dma_pfn_offset: offset of DMA memory range relatively of RAM
 * @dma_parms: A low level driver may set these to teach IOMMU code about
 *   segment limitations.
 * @dma_pools: Dma pools (if dma'ble device).
 * @dma_mem: Internal for coherent mem override.
 * @cma_area: Contiguous memory area for dma allocations
 * @archdata: For arch-specific additions.
 * @of_node: Associated device tree node.
 * @fwnode: Associated device node supplied by platform firmware.
 * @devt: For creating the sysfs "dev".
 * @id:  device instance
 * @devres_lock: Spinlock to protect the resource of the device.
 * @devres_head: The resources list of the device.
 * @knode_class: The node used to add the device to the class list.
 * @class: The class of the device.
 * @groups: Optional attribute groups.
 * @release: Callback to free the device after all references have
 *   gone away. This should be set by the allocator of the
 *   device (i.e. the bus driver that discovered the device).
 * @iommu_group: IOMMU group the device belongs to.
 * @iommu_fwspec: IOMMU-specific properties supplied by firmware.
 *
 * @offline_disabled: If set, the device is permanently online.
 * @offline: Set after successful invocation of bus type's .offline().
 *
 * At the lowest level, every device in a Linux system is represented by an
 * instance of struct device. The device structure contains the information
 * that the device model core needs to model the system. Most subsystems,
 * however, track additional information about the devices they host. As a
 * result, it is rare for devices to be represented by bare device structures;
 * instead, that structure, like kobject structures, is usually embedded within
 * a higher-level representation of the device.
 */
struct device {
 struct device  *parent;
 struct device_private *p;
 struct kobject kobj;
 const char  *init_name; /* initial name of the device */
 const struct device_type *type;
 struct mutex  mutex; /* mutex to synchronize calls to
      * its driver.
      */
 struct bus_type *bus;  /* type of bus device is on */
 struct device_driver *driver; /* which driver has allocated this
        device */
 void  *platform_data; /* Platform specific data, device
        core doesn't touch it */
 void  *driver_data; /* Driver data, set and get with
        dev_set/get_drvdata */
 struct dev_pm_info power;
 struct dev_pm_domain *pm_domain;
#ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
 struct irq_domain *msi_domain;
#endif
#ifdef CONFIG_PINCTRL
 struct dev_pin_info *pins;
#endif
#ifdef CONFIG_GENERIC_MSI_IRQ
 struct list_head msi_list;
#endif
#ifdef CONFIG_NUMA
 int  numa_node; /* NUMA node this device is close to */
#endif
 u64  *dma_mask; /* dma mask (if dma'able device) */
 u64  coherent_dma_mask;/* Like dma_mask, but for
          alloc_coherent mappings as
          not all hardware supports
          64 bit addresses for consistent
          allocations such descriptors. */
 unsigned long dma_pfn_offset;
 struct device_dma_parameters *dma_parms;
 struct list_head dma_pools; /* dma pools (if dma'ble) */
 struct dma_coherent_mem *dma_mem; /* internal for coherent mem
          override */
#ifdef CONFIG_DMA_CMA
 struct cma *cma_area;  /* contiguous memory area for dma
        allocations */
#endif
 /* arch specific additions */
 struct dev_archdata archdata;
 struct device_node *of_node; /* associated device tree node */
 struct fwnode_handle *fwnode; /* firmware device node */
 dev_t   devt; /* dev_t, creates the sysfs "dev" */
 u32   id; /* device instance */
 spinlock_t  devres_lock;
 struct list_head devres_head;
 struct klist_node knode_class;
 struct class  *class;
 const struct attribute_group **groups; /* optional groups */
 void (*release)(struct device *dev);
 struct iommu_group *iommu_group;
 struct iommu_fwspec *iommu_fwspec;
 bool   offline_disabled:1;
 bool   offline:1;
};