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;
         void * driver_data;
         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;
       #endif
         u64 * dma_mask;
         u64 coherent_dma_mask;
         unsigned long dma_pfn_offset;
         struct device_dma_parameters * dma_parms;
         struct list_head dma_pools;
         struct dma_coherent_mem * dma_mem;
       #ifdef CONFIG_DMA_CMA
         struct cma * cma_area;
       #endif
         struct dev_archdata archdata;
         struct device_node * of_node;
         struct fwnode_handle * fwnode;
         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.

       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.

       msi_domain
           The generic MSI domain this device is using.

       pins
           For device pin management. See Documentation/pinctrl.txt for details.

       msi_list
           Hosts MSI descriptors

       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.

       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.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                          STRUCT DEVICE(9)