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STRUCT DEVICE(9) Device drivers infrastructure STRUCT DEVICE(9)

NAME

struct_device - The basic device structure

SYNOPSIS

struct device {
  struct device * parent;
  struct device_private * p;
  struct kobject kobj;
  const char * init_name;
  const struct device_type * type;
  struct mutex mutex;
  struct bus_type * bus;
  struct device_driver * driver;
  void * platform_data;
  struct dev_pm_info power;
  struct dev_pm_domain * pm_domain;
#ifdef CONFIG_NUMA
  int numa_node;
#endif
  u64 * dma_mask;
  u64 coherent_dma_mask;
  struct device_dma_parameters * dma_parms;
  struct list_head dma_pools;
  struct dma_coherent_mem * dma_mem;
  struct dev_archdata archdata;
  struct device_node * of_node;
  dev_t devt;
  spinlock_t devres_lock;
  struct list_head devres_head;
  struct klist_node knode_class;
  struct class * class;
  const struct attribute_group ** groups;
  void (* release) (struct device *dev);
};

MEMBERS

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.
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.
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_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.
archdata
For arch-specific additions.
of_node
Associated device tree node.
devt
For creating the sysfs “dev”.
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).

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.

DESCRIPTION

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.

COPYRIGHT

March 2016 Kernel Hackers Manual 3.2.