struct device
Every device in a Linux system is represented by an instance of a struct device.
Typically, the
struct device is embedded into another
struct that has more detailed information for the embedding device (for example
struct pci_dev or
struct cpu).
struct device {
struct kobject kobj;
struct device *parent; /* If null: a top-level device (usually not interestting). Otherwise typically a bus or host controller.
struct device_private *p; /* The private data */
const char *init_name; /* initial name of the device */
const struct device_type *type; /* type of the device */
const struct bus_type *bus; /* type of bus device is on */
struct device_driver *driver; /* The driver that has allocated the device */
void *platform_data; /* Platform specific data, device core doesn't touch it */
void *driver_data; /* Driver data. Use dev_set_drvdata()/dev_get_drvdata() */
struct mutex mutex; /* mutex to synchronize calls to its driver. */
struct dev_links_info links; /* Linkx to suppliers and consumers of this device */
struct dev_pm_info power; /* Device Power management (see Documentation/driver-api/pm/devices.rst)
struct dev_pm_domain *pm_domain; /* callbacks that are executed during system suspend, hibernation, system resume and during runtime PM transitions; along with subsystem-level and driver-level callbacks. */
#ifdef CONFIG_ENERGY_MODEL
struct em_perf_domain *em_pd; /* energy model performance domain */
#endif
#ifdef CONFIG_PINCTRL
struct dev_pin_info *pins; /* See Documentation/driver-api/pin-control.rst */
#endif
struct dev_msi_info msi; /* Message Signaled Interruptions related data */
#ifdef CONFIG_DMA_OPS
const struct dma_map_ops *dma_ops; /* DMA mapping operations for this device */
#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. */
u64 bus_dma_limit; /* Limit of an upstream bridge or bus which imposes a smaller DMA limit than the device itself supports.
const struct bus_dma_region *dma_range_map; /* map for DMA memory ranges relative to that of RAM */
struct device_dma_parameters *dma_parms;
struct list_head dma_pools; /* dma pools (if dma'ble) */
#ifdef CONFIG_DMA_DECLARE_COHERENT
struct dma_coherent_mem *dma_mem; /* internal for coherent mem override */
#endif
#ifdef CONFIG_DMA_CMA
struct cma *cma_area; /* contiguous memory area for dma allocations */
#endif
#ifdef CONFIG_SWIOTLB
struct io_tlb_mem *dma_io_tlb_mem; /* Software IO TLB allocator. Not for driver use. */
#endif
#ifdef CONFIG_SWIOTLB_DYNAMIC
struct list_head dma_io_tlb_pools;
spinlock_t dma_io_tlb_lock;
bool dma_uses_io_tlb;
#endif
struct dev_archdata archdata; /* arch specific additions */
struct device_node *of_node; /* associated device tree node */
struct fwnode_handle *fwnode; /* assocated deivce node supplied by platform firmware */
#ifdef CONFIG_NUMA
int numa_node; /* NUMA node this device is close to */
#endif
dev_t devt; /* To create the sysfs "dev" */
u32 id; /* device instance */
spinlock_t devres_lock; /* Spinlock to protect the resource of the device */
struct list_head devres_head; /* The resource list of the device */
const struct class *class; /* The device's class */
const struct attribute_group **groups; /* optional attribute groups */
void (*release)(struct device *dev); /* Callback to free the device after all references have gone away - should be set by the allocateor of the device, i. e. the bus driver that discovered the device */
struct iommu_group *iommu_group; /* Input-output memory (IOMMU) group the device belongs to */
struct dev_iommu *iommu; /* Per device generic IOMMU runtime data */
struct device_physical_location *physical_location;
enum device_removable removable;
bool offline_disabled:1;
bool offline:1;
bool of_node_reused:1;
bool state_synced:1;
bool can_match:1;
#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
bool dma_coherent:1;
#endif
#ifdef CONFIG_DMA_OPS_BYPASS
bool dma_ops_bypass : 1;
#endif
};
struct device_type
A device type carries type-specific information.
struct device has a pointer to struct device_type
Note the uevent function pointer.
struct device_type {
const char *name;
const struct attribute_group **groups;
int (*uevent)(const struct device *dev, struct kobj_uevent_env *env);
char *(*devnode)(const struct device *dev, umode_t *mode,
kuid_t *uid, kgid_t *gid);
void (*release)(struct device *dev);
const struct dev_pm_ops *pm;
}