STRUCT DEVICE(9) Device drivers infrastructure STRUCT DEVICE(9)NAMEstruct_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_PINCTRL
struct dev_pin_info * pins;
#endif
#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;
#ifdef CONFIG_CMA
struct cma * cma_area;
#endif
struct dev_archdata archdata;
struct device_node * of_node;
struct acpi_dev_node acpi_node;
dev_t devt;
u32 id;
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);
struct iommu_group * iommu_group;
bool offline_disabled:1;
bool offline:1;
};
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.
pins
For device pin management. See Documentation/pinctrl.txt for
details.
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.
cma_area
Contiguous memory area for dma allocations
archdata
For arch-specific additions.
of_node
Associated device tree node.
acpi_node
Associated ACPI device node.
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.
offline_disabled
If set, the device is permanently online.
offline
Set after successful invocation of bus type's .offline.
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.
COPYRIGHTKernel Hackers Manual 3.11 November 2013 STRUCT DEVICE(9)
