2 * Copyright (c) 2013 Google, Inc
5 * Pavel Herrmann <morpheus.ibis@gmail.com>
6 * Marek Vasut <marex@denx.de>
8 * SPDX-License-Identifier: GPL-2.0+
14 #include <dm/uclass-id.h>
16 #include <linker_lists.h>
17 #include <linux/compat.h>
18 #include <linux/kernel.h>
19 #include <linux/list.h>
23 /* Driver is active (probed). Cleared when it is removed */
24 #define DM_FLAG_ACTIVATED (1 << 0)
26 /* DM is responsible for allocating and freeing platdata */
27 #define DM_FLAG_ALLOC_PDATA (1 << 1)
29 /* DM should init this device prior to relocation */
30 #define DM_FLAG_PRE_RELOC (1 << 2)
32 /* DM is responsible for allocating and freeing parent_platdata */
33 #define DM_FLAG_ALLOC_PARENT_PDATA (1 << 3)
35 /* DM is responsible for allocating and freeing uclass_platdata */
36 #define DM_FLAG_ALLOC_UCLASS_PDATA (1 << 4)
38 /* Allocate driver private data on a DMA boundary */
39 #define DM_FLAG_ALLOC_PRIV_DMA (1 << 5)
42 #define DM_FLAG_BOUND (1 << 6)
45 * struct udevice - An instance of a driver
47 * This holds information about a device, which is a driver bound to a
48 * particular port or peripheral (essentially a driver instance).
50 * A device will come into existence through a 'bind' call, either due to
51 * a U_BOOT_DEVICE() macro (in which case platdata is non-NULL) or a node
52 * in the device tree (in which case of_offset is >= 0). In the latter case
53 * we translate the device tree information into platdata in a function
54 * implemented by the driver ofdata_to_platdata method (called just before the
55 * probe method if the device has a device tree node.
57 * All three of platdata, priv and uclass_priv can be allocated by the
58 * driver, or you can use the auto_alloc_size members of struct driver and
59 * struct uclass_driver to have driver model do this automatically.
61 * @driver: The driver used by this device
62 * @name: Name of device, typically the FDT node name
63 * @platdata: Configuration data for this device
64 * @parent_platdata: The parent bus's configuration data for this device
65 * @uclass_platdata: The uclass's configuration data for this device
66 * @of_offset: Device tree node offset for this device (- for none)
67 * @driver_data: Driver data word for the entry that matched this device with
69 * @parent: Parent of this device, or NULL for the top level device
70 * @priv: Private data for this device
71 * @uclass: Pointer to uclass for this device
72 * @uclass_priv: The uclass's private data for this device
73 * @parent_priv: The parent's private data for this device
74 * @uclass_node: Used by uclass to link its devices
75 * @child_head: List of children of this device
76 * @sibling_node: Next device in list of all devices
77 * @flags: Flags for this device DM_FLAG_...
78 * @req_seq: Requested sequence number for this device (-1 = any)
79 * @seq: Allocated sequence number for this device (-1 = none). This is set up
80 * when the device is probed and will be unique within the device's uclass.
81 * @devres_head: List of memory allocations associated with this device.
82 * When CONFIG_DEVRES is enabled, devm_kmalloc() and friends will
83 * add to this list. Memory so-allocated will be freed
84 * automatically when the device is removed / unbound
87 const struct driver *driver;
90 void *parent_platdata;
91 void *uclass_platdata;
94 struct udevice *parent;
96 struct uclass *uclass;
99 struct list_head uclass_node;
100 struct list_head child_head;
101 struct list_head sibling_node;
106 struct list_head devres_head;
110 /* Maximum sequence number supported */
111 #define DM_MAX_SEQ 999
113 /* Returns the operations for a device */
114 #define device_get_ops(dev) (dev->driver->ops)
116 /* Returns non-zero if the device is active (probed and not removed) */
117 #define device_active(dev) ((dev)->flags & DM_FLAG_ACTIVATED)
120 * struct udevice_id - Lists the compatible strings supported by a driver
121 * @compatible: Compatible string
122 * @data: Data for this compatible string
125 const char *compatible;
129 #if CONFIG_IS_ENABLED(OF_CONTROL)
130 #define of_match_ptr(_ptr) (_ptr)
132 #define of_match_ptr(_ptr) NULL
133 #endif /* CONFIG_IS_ENABLED(OF_CONTROL) */
136 * struct driver - A driver for a feature or peripheral
138 * This holds methods for setting up a new device, and also removing it.
139 * The device needs information to set itself up - this is provided either
140 * by platdata or a device tree node (which we find by looking up
141 * matching compatible strings with of_match).
143 * Drivers all belong to a uclass, representing a class of devices of the
144 * same type. Common elements of the drivers can be implemented in the uclass,
145 * or the uclass can provide a consistent interface to the drivers within
149 * @id: Identiies the uclass we belong to
150 * @of_match: List of compatible strings to match, and any identifying data
152 * @bind: Called to bind a device to its driver
153 * @probe: Called to probe a device, i.e. activate it
154 * @remove: Called to remove a device, i.e. de-activate it
155 * @unbind: Called to unbind a device from its driver
156 * @ofdata_to_platdata: Called before probe to decode device tree data
157 * @child_post_bind: Called after a new child has been bound
158 * @child_pre_probe: Called before a child device is probed. The device has
159 * memory allocated but it has not yet been probed.
160 * @child_post_remove: Called after a child device is removed. The device
161 * has memory allocated but its device_remove() method has been called.
162 * @priv_auto_alloc_size: If non-zero this is the size of the private data
163 * to be allocated in the device's ->priv pointer. If zero, then the driver
164 * is responsible for allocating any data required.
165 * @platdata_auto_alloc_size: If non-zero this is the size of the
166 * platform data to be allocated in the device's ->platdata pointer.
167 * This is typically only useful for device-tree-aware drivers (those with
168 * an of_match), since drivers which use platdata will have the data
169 * provided in the U_BOOT_DEVICE() instantiation.
170 * @per_child_auto_alloc_size: Each device can hold private data owned by
171 * its parent. If required this will be automatically allocated if this
173 * @per_child_platdata_auto_alloc_size: A bus likes to store information about
174 * its children. If non-zero this is the size of this data, to be allocated
175 * in the child's parent_platdata pointer.
176 * @ops: Driver-specific operations. This is typically a list of function
177 * pointers defined by the driver, to implement driver functions required by
179 * @flags: driver flags - see DM_FLAGS_...
184 const struct udevice_id *of_match;
185 int (*bind)(struct udevice *dev);
186 int (*probe)(struct udevice *dev);
187 int (*remove)(struct udevice *dev);
188 int (*unbind)(struct udevice *dev);
189 int (*ofdata_to_platdata)(struct udevice *dev);
190 int (*child_post_bind)(struct udevice *dev);
191 int (*child_pre_probe)(struct udevice *dev);
192 int (*child_post_remove)(struct udevice *dev);
193 int priv_auto_alloc_size;
194 int platdata_auto_alloc_size;
195 int per_child_auto_alloc_size;
196 int per_child_platdata_auto_alloc_size;
197 const void *ops; /* driver-specific operations */
201 /* Declare a new U-Boot driver */
202 #define U_BOOT_DRIVER(__name) \
203 ll_entry_declare(struct driver, __name, driver)
206 * dev_get_platdata() - Get the platform data for a device
208 * This checks that dev is not NULL, but no other checks for now
210 * @dev Device to check
211 * @return platform data, or NULL if none
213 void *dev_get_platdata(struct udevice *dev);
216 * dev_get_parent_platdata() - Get the parent platform data for a device
218 * This checks that dev is not NULL, but no other checks for now
220 * @dev Device to check
221 * @return parent's platform data, or NULL if none
223 void *dev_get_parent_platdata(struct udevice *dev);
226 * dev_get_uclass_platdata() - Get the uclass platform data for a device
228 * This checks that dev is not NULL, but no other checks for now
230 * @dev Device to check
231 * @return uclass's platform data, or NULL if none
233 void *dev_get_uclass_platdata(struct udevice *dev);
236 * dev_get_priv() - Get the private data for a device
238 * This checks that dev is not NULL, but no other checks for now
240 * @dev Device to check
241 * @return private data, or NULL if none
243 void *dev_get_priv(struct udevice *dev);
246 * dev_get_parent_priv() - Get the parent private data for a device
248 * The parent private data is data stored in the device but owned by the
249 * parent. For example, a USB device may have parent data which contains
250 * information about how to talk to the device over USB.
252 * This checks that dev is not NULL, but no other checks for now
254 * @dev Device to check
255 * @return parent data, or NULL if none
257 void *dev_get_parent_priv(struct udevice *dev);
260 * dev_get_uclass_priv() - Get the private uclass data for a device
262 * This checks that dev is not NULL, but no other checks for now
264 * @dev Device to check
265 * @return private uclass data for this device, or NULL if none
267 void *dev_get_uclass_priv(struct udevice *dev);
270 * struct dev_get_parent() - Get the parent of a device
272 * @child: Child to check
273 * @return parent of child, or NULL if this is the root device
275 struct udevice *dev_get_parent(struct udevice *child);
278 * dev_get_driver_data() - get the driver data used to bind a device
280 * When a device is bound using a device tree node, it matches a
281 * particular compatible string in struct udevice_id. This function
282 * returns the associated data value for that compatible string. This is
283 * the 'data' field in struct udevice_id.
285 * As an example, consider this structure:
286 * static const struct udevice_id tegra_i2c_ids[] = {
287 * { .compatible = "nvidia,tegra114-i2c", .data = TYPE_114 },
288 * { .compatible = "nvidia,tegra20-i2c", .data = TYPE_STD },
289 * { .compatible = "nvidia,tegra20-i2c-dvc", .data = TYPE_DVC },
293 * When driver model finds a driver for this it will store the 'data' value
294 * corresponding to the compatible string it matches. This function returns
295 * that value. This allows the driver to handle several variants of a device.
297 * For USB devices, this is the driver_info field in struct usb_device_id.
299 * @dev: Device to check
300 * @return driver data (0 if none is provided)
302 ulong dev_get_driver_data(struct udevice *dev);
305 * dev_get_driver_ops() - get the device's driver's operations
307 * This checks that dev is not NULL, and returns the pointer to device's
308 * driver's operations.
310 * @dev: Device to check
311 * @return void pointer to driver's operations or NULL for NULL-dev or NULL-ops
313 const void *dev_get_driver_ops(struct udevice *dev);
316 * device_get_uclass_id() - return the uclass ID of a device
318 * @dev: Device to check
319 * @return uclass ID for the device
321 enum uclass_id device_get_uclass_id(struct udevice *dev);
324 * dev_get_uclass_name() - return the uclass name of a device
326 * This checks that dev is not NULL.
328 * @dev: Device to check
329 * @return pointer to the uclass name for the device
331 const char *dev_get_uclass_name(struct udevice *dev);
334 * device_get_child() - Get the child of a device by index
336 * Returns the numbered child, 0 being the first. This does not use
337 * sequence numbers, only the natural order.
339 * @dev: Parent device to check
340 * @index: Child index
341 * @devp: Returns pointer to device
342 * @return 0 if OK, -ENODEV if no such device, other error if the device fails
345 int device_get_child(struct udevice *parent, int index, struct udevice **devp);
348 * device_find_child_by_seq() - Find a child device based on a sequence
350 * This searches for a device with the given seq or req_seq.
352 * For seq, if an active device has this sequence it will be returned.
353 * If there is no such device then this will return -ENODEV.
355 * For req_seq, if a device (whether activated or not) has this req_seq
356 * value, that device will be returned. This is a strong indication that
357 * the device will receive that sequence when activated.
359 * @parent: Parent device
360 * @seq_or_req_seq: Sequence number to find (0=first)
361 * @find_req_seq: true to find req_seq, false to find seq
362 * @devp: Returns pointer to device (there is only one per for each seq).
363 * Set to NULL if none is found
364 * @return 0 if OK, -ve on error
366 int device_find_child_by_seq(struct udevice *parent, int seq_or_req_seq,
367 bool find_req_seq, struct udevice **devp);
370 * device_get_child_by_seq() - Get a child device based on a sequence
372 * If an active device has this sequence it will be returned. If there is no
373 * such device then this will check for a device that is requesting this
376 * The device is probed to activate it ready for use.
378 * @parent: Parent device
379 * @seq: Sequence number to find (0=first)
380 * @devp: Returns pointer to device (there is only one per for each seq)
381 * Set to NULL if none is found
382 * @return 0 if OK, -ve on error
384 int device_get_child_by_seq(struct udevice *parent, int seq,
385 struct udevice **devp);
388 * device_find_child_by_of_offset() - Find a child device based on FDT offset
390 * Locates a child device by its device tree offset.
392 * @parent: Parent device
393 * @of_offset: Device tree offset to find
394 * @devp: Returns pointer to device if found, otherwise this is set to NULL
395 * @return 0 if OK, -ve on error
397 int device_find_child_by_of_offset(struct udevice *parent, int of_offset,
398 struct udevice **devp);
401 * device_get_child_by_of_offset() - Get a child device based on FDT offset
403 * Locates a child device by its device tree offset.
405 * The device is probed to activate it ready for use.
407 * @parent: Parent device
408 * @of_offset: Device tree offset to find
409 * @devp: Returns pointer to device if found, otherwise this is set to NULL
410 * @return 0 if OK, -ve on error
412 int device_get_child_by_of_offset(struct udevice *parent, int of_offset,
413 struct udevice **devp);
416 * device_get_global_by_of_offset() - Get a device based on FDT offset
418 * Locates a device by its device tree offset, searching globally throughout
419 * the all driver model devices.
421 * The device is probed to activate it ready for use.
423 * @of_offset: Device tree offset to find
424 * @devp: Returns pointer to device if found, otherwise this is set to NULL
425 * @return 0 if OK, -ve on error
427 int device_get_global_by_of_offset(int of_offset, struct udevice **devp);
430 * device_find_first_child() - Find the first child of a device
432 * @parent: Parent device to search
433 * @devp: Returns first child device, or NULL if none
436 int device_find_first_child(struct udevice *parent, struct udevice **devp);
439 * device_find_next_child() - Find the next child of a device
441 * @devp: Pointer to previous child device on entry. Returns pointer to next
442 * child device, or NULL if none
445 int device_find_next_child(struct udevice **devp);
448 * dev_get_addr() - Get the reg property of a device
450 * @dev: Pointer to a device
454 fdt_addr_t dev_get_addr(struct udevice *dev);
457 * dev_get_addr_ptr() - Return pointer to the address of the reg property
460 * @dev: Pointer to a device
462 * @return Pointer to addr, or NULL if there is no such property
464 void *dev_get_addr_ptr(struct udevice *dev);
467 * dev_get_addr_index() - Get the indexed reg property of a device
469 * @dev: Pointer to a device
470 * @index: the 'reg' property can hold a list of <addr, size> pairs
471 * and @index is used to select which one is required
475 fdt_addr_t dev_get_addr_index(struct udevice *dev, int index);
478 * dev_get_addr_name() - Get the reg property of a device, indexed by name
480 * @dev: Pointer to a device
481 * @name: the 'reg' property can hold a list of <addr, size> pairs, with the
482 * 'reg-names' property providing named-based identification. @index
483 * indicates the value to search for in 'reg-names'.
487 fdt_addr_t dev_get_addr_name(struct udevice *dev, const char *name);
490 * device_has_children() - check if a device has any children
492 * @dev: Device to check
493 * @return true if the device has one or more children
495 bool device_has_children(struct udevice *dev);
498 * device_has_active_children() - check if a device has any active children
500 * @dev: Device to check
501 * @return true if the device has one or more children and at least one of
502 * them is active (probed).
504 bool device_has_active_children(struct udevice *dev);
507 * device_is_last_sibling() - check if a device is the last sibling
509 * This function can be useful for display purposes, when special action needs
510 * to be taken when displaying the last sibling. This can happen when a tree
511 * view of devices is being displayed.
513 * @dev: Device to check
514 * @return true if there are no more siblings after this one - i.e. is it
517 bool device_is_last_sibling(struct udevice *dev);
520 * device_set_name() - set the name of a device
522 * This must be called in the device's bind() method and no later. Normally
523 * this is unnecessary but for probed devices which don't get a useful name
524 * this function can be helpful.
526 * @dev: Device to update
527 * @name: New name (this string is allocated new memory and attached to
529 * @return 0 if OK, -ENOMEM if there is not enough memory to allocate the
532 int device_set_name(struct udevice *dev, const char *name);
535 * device_is_on_pci_bus - Test if a device is on a PCI bus
537 * @dev: device to test
538 * @return: true if it is on a PCI bus, false otherwise
540 static inline bool device_is_on_pci_bus(struct udevice *dev)
542 return device_get_uclass_id(dev->parent) == UCLASS_PCI;
546 * device_foreach_child_safe() - iterate through child devices safely
548 * This allows the @pos child to be removed in the loop if required.
550 * @pos: struct udevice * for the current device
551 * @next: struct udevice * for the next device
552 * @parent: parent device to scan
554 #define device_foreach_child_safe(pos, next, parent) \
555 list_for_each_entry_safe(pos, next, &parent->child_head, sibling_node)
557 /* device resource management */
558 typedef void (*dr_release_t)(struct udevice *dev, void *res);
559 typedef int (*dr_match_t)(struct udevice *dev, void *res, void *match_data);
563 #ifdef CONFIG_DEBUG_DEVRES
564 void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
566 #define _devres_alloc(release, size, gfp) \
567 __devres_alloc(release, size, gfp, #release)
569 void *_devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
573 * devres_alloc() - Allocate device resource data
574 * @release: Release function devres will be associated with
575 * @size: Allocation size
576 * @gfp: Allocation flags
578 * Allocate devres of @size bytes. The allocated area is associated
579 * with @release. The returned pointer can be passed to
580 * other devres_*() functions.
583 * Pointer to allocated devres on success, NULL on failure.
585 #define devres_alloc(release, size, gfp) \
586 _devres_alloc(release, size, gfp | __GFP_ZERO)
589 * devres_free() - Free device resource data
590 * @res: Pointer to devres data to free
592 * Free devres created with devres_alloc().
594 void devres_free(void *res);
597 * devres_add() - Register device resource
598 * @dev: Device to add resource to
599 * @res: Resource to register
601 * Register devres @res to @dev. @res should have been allocated
602 * using devres_alloc(). On driver detach, the associated release
603 * function will be invoked and devres will be freed automatically.
605 void devres_add(struct udevice *dev, void *res);
608 * devres_find() - Find device resource
609 * @dev: Device to lookup resource from
610 * @release: Look for resources associated with this release function
611 * @match: Match function (optional)
612 * @match_data: Data for the match function
614 * Find the latest devres of @dev which is associated with @release
615 * and for which @match returns 1. If @match is NULL, it's considered
618 * @return pointer to found devres, NULL if not found.
620 void *devres_find(struct udevice *dev, dr_release_t release,
621 dr_match_t match, void *match_data);
624 * devres_get() - Find devres, if non-existent, add one atomically
625 * @dev: Device to lookup or add devres for
626 * @new_res: Pointer to new initialized devres to add if not found
627 * @match: Match function (optional)
628 * @match_data: Data for the match function
630 * Find the latest devres of @dev which has the same release function
631 * as @new_res and for which @match return 1. If found, @new_res is
632 * freed; otherwise, @new_res is added atomically.
634 * @return ointer to found or added devres.
636 void *devres_get(struct udevice *dev, void *new_res,
637 dr_match_t match, void *match_data);
640 * devres_remove() - Find a device resource and remove it
641 * @dev: Device to find resource from
642 * @release: Look for resources associated with this release function
643 * @match: Match function (optional)
644 * @match_data: Data for the match function
646 * Find the latest devres of @dev associated with @release and for
647 * which @match returns 1. If @match is NULL, it's considered to
648 * match all. If found, the resource is removed atomically and
651 * @return ointer to removed devres on success, NULL if not found.
653 void *devres_remove(struct udevice *dev, dr_release_t release,
654 dr_match_t match, void *match_data);
657 * devres_destroy() - Find a device resource and destroy it
658 * @dev: Device to find resource from
659 * @release: Look for resources associated with this release function
660 * @match: Match function (optional)
661 * @match_data: Data for the match function
663 * Find the latest devres of @dev associated with @release and for
664 * which @match returns 1. If @match is NULL, it's considered to
665 * match all. If found, the resource is removed atomically and freed.
667 * Note that the release function for the resource will not be called,
668 * only the devres-allocated data will be freed. The caller becomes
669 * responsible for freeing any other data.
671 * @return 0 if devres is found and freed, -ENOENT if not found.
673 int devres_destroy(struct udevice *dev, dr_release_t release,
674 dr_match_t match, void *match_data);
677 * devres_release() - Find a device resource and destroy it, calling release
678 * @dev: Device to find resource from
679 * @release: Look for resources associated with this release function
680 * @match: Match function (optional)
681 * @match_data: Data for the match function
683 * Find the latest devres of @dev associated with @release and for
684 * which @match returns 1. If @match is NULL, it's considered to
685 * match all. If found, the resource is removed atomically, the
686 * release function called and the resource freed.
688 * @return 0 if devres is found and freed, -ENOENT if not found.
690 int devres_release(struct udevice *dev, dr_release_t release,
691 dr_match_t match, void *match_data);
693 /* managed devm_k.alloc/kfree for device drivers */
695 * devm_kmalloc() - Resource-managed kmalloc
696 * @dev: Device to allocate memory for
697 * @size: Allocation size
698 * @gfp: Allocation gfp flags
700 * Managed kmalloc. Memory allocated with this function is
701 * automatically freed on driver detach. Like all other devres
702 * resources, guaranteed alignment is unsigned long long.
704 * @return pointer to allocated memory on success, NULL on failure.
706 void *devm_kmalloc(struct udevice *dev, size_t size, gfp_t gfp);
707 static inline void *devm_kzalloc(struct udevice *dev, size_t size, gfp_t gfp)
709 return devm_kmalloc(dev, size, gfp | __GFP_ZERO);
711 static inline void *devm_kmalloc_array(struct udevice *dev,
712 size_t n, size_t size, gfp_t flags)
714 if (size != 0 && n > SIZE_MAX / size)
716 return devm_kmalloc(dev, n * size, flags);
718 static inline void *devm_kcalloc(struct udevice *dev,
719 size_t n, size_t size, gfp_t flags)
721 return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
725 * devm_kfree() - Resource-managed kfree
726 * @dev: Device this memory belongs to
727 * @ptr: Memory to free
729 * Free memory allocated with devm_kmalloc().
731 void devm_kfree(struct udevice *dev, void *ptr);
733 #else /* ! CONFIG_DEVRES */
735 static inline void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp)
737 return kzalloc(size, gfp);
740 static inline void devres_free(void *res)
745 static inline void devres_add(struct udevice *dev, void *res)
749 static inline void *devres_find(struct udevice *dev, dr_release_t release,
750 dr_match_t match, void *match_data)
755 static inline void *devres_get(struct udevice *dev, void *new_res,
756 dr_match_t match, void *match_data)
761 static inline void *devres_remove(struct udevice *dev, dr_release_t release,
762 dr_match_t match, void *match_data)
767 static inline int devres_destroy(struct udevice *dev, dr_release_t release,
768 dr_match_t match, void *match_data)
773 static inline int devres_release(struct udevice *dev, dr_release_t release,
774 dr_match_t match, void *match_data)
779 static inline void *devm_kmalloc(struct udevice *dev, size_t size, gfp_t gfp)
781 return kmalloc(size, gfp);
784 static inline void *devm_kzalloc(struct udevice *dev, size_t size, gfp_t gfp)
786 return kzalloc(size, gfp);
789 static inline void *devm_kmaloc_array(struct udevice *dev,
790 size_t n, size_t size, gfp_t flags)
792 /* TODO: add kmalloc_array() to linux/compat.h */
793 if (size != 0 && n > SIZE_MAX / size)
795 return kmalloc(n * size, flags);
798 static inline void *devm_kcalloc(struct udevice *dev,
799 size_t n, size_t size, gfp_t flags)
801 /* TODO: add kcalloc() to linux/compat.h */
802 return kmalloc(n * size, flags | __GFP_ZERO);
805 static inline void devm_kfree(struct udevice *dev, void *ptr)
810 #endif /* ! CONFIG_DEVRES */
813 * dm_set_translation_offset() - Set translation offset
814 * @offs: Translation offset
816 * Some platforms need a special address translation. Those
817 * platforms (e.g. mvebu in SPL) can configure a translation
818 * offset in the DM by calling this function. It will be
819 * added to all addresses returned in dev_get_addr().
821 void dm_set_translation_offset(fdt_addr_t offs);
824 * dm_get_translation_offset() - Get translation offset
826 * This function returns the translation offset that can
827 * be configured by calling dm_set_translation_offset().
829 * @return translation offset for the device address (0 as default).
831 fdt_addr_t dm_get_translation_offset(void);