1 /* SPDX-License-Identifier: GPL-2.0 */
6 * This header file contains MSI data structures and functions which are
8 * - Interrupt core code
10 * - MSI interrupt domain implementations
11 * - IOMMU, low level VFIO, NTB and other justified exceptions
12 * dealing with low level MSI details.
14 * Regular device drivers have no business with any of these functions and
15 * especially storing MSI descriptor pointers in random code is considered
18 * Device driver relevant functions are available in <linux/msi_api.h>
21 #include <linux/irqdomain_defs.h>
22 #include <linux/cpumask_types.h>
23 #include <linux/msi_api.h>
24 #include <linux/irq.h>
28 /* Dummy shadow structures if an architecture does not define them */
29 #ifndef arch_msi_msg_addr_lo
30 typedef struct arch_msi_msg_addr_lo
{
32 } __attribute__ ((packed
)) arch_msi_msg_addr_lo_t
;
35 #ifndef arch_msi_msg_addr_hi
36 typedef struct arch_msi_msg_addr_hi
{
38 } __attribute__ ((packed
)) arch_msi_msg_addr_hi_t
;
41 #ifndef arch_msi_msg_data
42 typedef struct arch_msi_msg_data
{
44 } __attribute__ ((packed
)) arch_msi_msg_data_t
;
47 #ifndef arch_is_isolated_msi
48 #define arch_is_isolated_msi() false
52 * msi_msg - Representation of a MSI message
53 * @address_lo: Low 32 bits of msi message address
54 * @arch_addrlo: Architecture specific shadow of @address_lo
55 * @address_hi: High 32 bits of msi message address
56 * (only used when device supports it)
57 * @arch_addrhi: Architecture specific shadow of @address_hi
58 * @data: MSI message data (usually 16 bits)
59 * @arch_data: Architecture specific shadow of @data
64 arch_msi_msg_addr_lo_t arch_addr_lo
;
68 arch_msi_msg_addr_hi_t arch_addr_hi
;
72 arch_msi_msg_data_t arch_data
;
76 extern int pci_msi_ignore_mask
;
77 /* Helper functions */
80 struct device_attribute
;
82 struct irq_affinity_desc
;
84 void __get_cached_msi_msg(struct msi_desc
*entry
, struct msi_msg
*msg
);
85 #ifdef CONFIG_GENERIC_MSI_IRQ
86 void get_cached_msi_msg(unsigned int irq
, struct msi_msg
*msg
);
88 static inline void get_cached_msi_msg(unsigned int irq
, struct msi_msg
*msg
) { }
91 typedef void (*irq_write_msi_msg_t
)(struct msi_desc
*desc
,
95 * pci_msi_desc - PCI/MSI specific MSI descriptor data
97 * @msi_mask: [PCI MSI] MSI cached mask bits
98 * @msix_ctrl: [PCI MSI-X] MSI-X cached per vector control bits
99 * @is_msix: [PCI MSI/X] True if MSI-X
100 * @multiple: [PCI MSI/X] log2 num of messages allocated
101 * @multi_cap: [PCI MSI/X] log2 num of messages supported
102 * @can_mask: [PCI MSI/X] Masking supported?
103 * @is_64: [PCI MSI/X] Address size: 0=32bit 1=64bit
104 * @default_irq:[PCI MSI/X] The default pre-assigned non-MSI irq
105 * @mask_pos: [PCI MSI] Mask register position
106 * @mask_base: [PCI MSI-X] Mask register base address
108 struct pci_msi_desc
{
120 unsigned default_irq
;
124 void __iomem
*mask_base
;
129 * union msi_domain_cookie - Opaque MSI domain specific data
130 * @value: u64 value store
131 * @ptr: Pointer to domain specific data
132 * @iobase: Domain specific IOmem pointer
134 * The content of this data is implementation defined and used by the MSI
135 * domain to store domain specific information which is requried for
136 * interrupt chip callbacks.
138 union msi_domain_cookie
{
141 void __iomem
*iobase
;
145 * struct msi_desc_data - Generic MSI descriptor data
146 * @dcookie: Cookie for MSI domain specific data which is required
147 * for irq_chip callbacks
148 * @icookie: Cookie for the MSI interrupt instance provided by
149 * the usage site to the allocation function
151 * The content of this data is implementation defined, e.g. PCI/IMS
152 * implementations define the meaning of the data. The MSI core ignores
153 * this data completely.
155 struct msi_desc_data
{
156 union msi_domain_cookie dcookie
;
157 union msi_instance_cookie icookie
;
160 #define MSI_MAX_INDEX ((unsigned int)USHRT_MAX)
163 * struct msi_desc - Descriptor structure for MSI based interrupts
164 * @irq: The base interrupt number
165 * @nvec_used: The number of vectors used
166 * @dev: Pointer to the device which uses this descriptor
167 * @msg: The last set MSI message cached for reuse
168 * @affinity: Optional pointer to a cpu affinity mask for this descriptor
169 * @sysfs_attr: Pointer to sysfs device attribute
171 * @write_msi_msg: Callback that may be called when the MSI message
172 * address or data changes
173 * @write_msi_msg_data: Data parameter for the callback.
175 * @msi_index: Index of the msi descriptor
176 * @pci: PCI specific msi descriptor data
177 * @data: Generic MSI descriptor data
180 /* Shared device/bus type independent data */
182 unsigned int nvec_used
;
185 struct irq_affinity_desc
*affinity
;
186 #ifdef CONFIG_IRQ_MSI_IOMMU
187 const void *iommu_cookie
;
190 struct device_attribute
*sysfs_attrs
;
193 void (*write_msi_msg
)(struct msi_desc
*entry
, void *data
);
194 void *write_msi_msg_data
;
198 struct pci_msi_desc pci
;
199 struct msi_desc_data data
;
204 * Filter values for the MSI descriptor iterators and accessor functions.
206 enum msi_desc_filter
{
207 /* All descriptors */
209 /* Descriptors which have no interrupt associated */
210 MSI_DESC_NOTASSOCIATED
,
211 /* Descriptors which have an interrupt associated */
217 * struct msi_dev_domain - The internals of MSI domain info per device
218 * @store: Xarray for storing MSI descriptor pointers
219 * @irqdomain: Pointer to a per device interrupt domain
221 struct msi_dev_domain
{
223 struct irq_domain
*domain
;
226 int msi_setup_device_data(struct device
*dev
);
228 void msi_lock_descs(struct device
*dev
);
229 void msi_unlock_descs(struct device
*dev
);
231 struct msi_desc
*msi_domain_first_desc(struct device
*dev
, unsigned int domid
,
232 enum msi_desc_filter filter
);
235 * msi_first_desc - Get the first MSI descriptor of the default irqdomain
236 * @dev: Device to operate on
237 * @filter: Descriptor state filter
239 * Must be called with the MSI descriptor mutex held, i.e. msi_lock_descs()
240 * must be invoked before the call.
242 * Return: Pointer to the first MSI descriptor matching the search
243 * criteria, NULL if none found.
245 static inline struct msi_desc
*msi_first_desc(struct device
*dev
,
246 enum msi_desc_filter filter
)
248 return msi_domain_first_desc(dev
, MSI_DEFAULT_DOMAIN
, filter
);
251 struct msi_desc
*msi_next_desc(struct device
*dev
, unsigned int domid
,
252 enum msi_desc_filter filter
);
255 * msi_domain_for_each_desc - Iterate the MSI descriptors in a specific domain
257 * @desc: struct msi_desc pointer used as iterator
258 * @dev: struct device pointer - device to iterate
259 * @domid: The id of the interrupt domain which should be walked.
260 * @filter: Filter for descriptor selection
263 * - The loop must be protected with a msi_lock_descs()/msi_unlock_descs()
265 * - It is safe to remove a retrieved MSI descriptor in the loop.
267 #define msi_domain_for_each_desc(desc, dev, domid, filter) \
268 for ((desc) = msi_domain_first_desc((dev), (domid), (filter)); (desc); \
269 (desc) = msi_next_desc((dev), (domid), (filter)))
272 * msi_for_each_desc - Iterate the MSI descriptors in the default irqdomain
274 * @desc: struct msi_desc pointer used as iterator
275 * @dev: struct device pointer - device to iterate
276 * @filter: Filter for descriptor selection
279 * - The loop must be protected with a msi_lock_descs()/msi_unlock_descs()
281 * - It is safe to remove a retrieved MSI descriptor in the loop.
283 #define msi_for_each_desc(desc, dev, filter) \
284 msi_domain_for_each_desc((desc), (dev), MSI_DEFAULT_DOMAIN, (filter))
286 #define msi_desc_to_dev(desc) ((desc)->dev)
288 #ifdef CONFIG_IRQ_MSI_IOMMU
289 static inline const void *msi_desc_get_iommu_cookie(struct msi_desc
*desc
)
291 return desc
->iommu_cookie
;
294 static inline void msi_desc_set_iommu_cookie(struct msi_desc
*desc
,
295 const void *iommu_cookie
)
297 desc
->iommu_cookie
= iommu_cookie
;
300 static inline const void *msi_desc_get_iommu_cookie(struct msi_desc
*desc
)
305 static inline void msi_desc_set_iommu_cookie(struct msi_desc
*desc
,
306 const void *iommu_cookie
)
311 int msi_domain_insert_msi_desc(struct device
*dev
, unsigned int domid
,
312 struct msi_desc
*init_desc
);
314 * msi_insert_msi_desc - Allocate and initialize a MSI descriptor in the
315 * default irqdomain and insert it at @init_desc->msi_index
316 * @dev: Pointer to the device for which the descriptor is allocated
317 * @init_desc: Pointer to an MSI descriptor to initialize the new descriptor
319 * Return: 0 on success or an appropriate failure code.
321 static inline int msi_insert_msi_desc(struct device
*dev
, struct msi_desc
*init_desc
)
323 return msi_domain_insert_msi_desc(dev
, MSI_DEFAULT_DOMAIN
, init_desc
);
326 void msi_domain_free_msi_descs_range(struct device
*dev
, unsigned int domid
,
327 unsigned int first
, unsigned int last
);
330 * msi_free_msi_descs_range - Free a range of MSI descriptors of a device
331 * in the default irqdomain
333 * @dev: Device for which to free the descriptors
334 * @first: Index to start freeing from (inclusive)
335 * @last: Last index to be freed (inclusive)
337 static inline void msi_free_msi_descs_range(struct device
*dev
, unsigned int first
,
340 msi_domain_free_msi_descs_range(dev
, MSI_DEFAULT_DOMAIN
, first
, last
);
344 * msi_free_msi_descs - Free all MSI descriptors of a device in the default irqdomain
345 * @dev: Device to free the descriptors
347 static inline void msi_free_msi_descs(struct device
*dev
)
349 msi_free_msi_descs_range(dev
, 0, MSI_MAX_INDEX
);
353 * The arch hooks to setup up msi irqs. Default functions are implemented
354 * as weak symbols so that they /can/ be overriden by architecture specific
355 * code if needed. These hooks can only be enabled by the architecture.
357 * If CONFIG_PCI_MSI_ARCH_FALLBACKS is not selected they are replaced by
358 * stubs with warnings.
360 #ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS
361 int arch_setup_msi_irq(struct pci_dev
*dev
, struct msi_desc
*desc
);
362 void arch_teardown_msi_irq(unsigned int irq
);
363 int arch_setup_msi_irqs(struct pci_dev
*dev
, int nvec
, int type
);
364 void arch_teardown_msi_irqs(struct pci_dev
*dev
);
365 #endif /* CONFIG_PCI_MSI_ARCH_FALLBACKS */
368 * Xen uses non-default msi_domain_ops and hence needs a way to populate sysfs
369 * entries of MSI IRQs.
371 #if defined(CONFIG_PCI_XEN) || defined(CONFIG_PCI_MSI_ARCH_FALLBACKS)
373 int msi_device_populate_sysfs(struct device
*dev
);
374 void msi_device_destroy_sysfs(struct device
*dev
);
375 #else /* CONFIG_SYSFS */
376 static inline int msi_device_populate_sysfs(struct device
*dev
) { return 0; }
377 static inline void msi_device_destroy_sysfs(struct device
*dev
) { }
378 #endif /* !CONFIG_SYSFS */
379 #endif /* CONFIG_PCI_XEN || CONFIG_PCI_MSI_ARCH_FALLBACKS */
382 * The restore hook is still available even for fully irq domain based
383 * setups. Courtesy to XEN/X86.
385 bool arch_restore_msi_irqs(struct pci_dev
*dev
);
387 #ifdef CONFIG_GENERIC_MSI_IRQ
389 #include <linux/irqhandler.h>
392 struct irq_domain_ops
;
396 struct fwnode_handle
;
397 struct msi_domain_info
;
400 * struct msi_domain_ops - MSI interrupt domain callbacks
401 * @get_hwirq: Retrieve the resulting hw irq number
402 * @msi_init: Domain specific init function for MSI interrupts
403 * @msi_free: Domain specific function to free a MSI interrupts
404 * @msi_prepare: Prepare the allocation of the interrupts in the domain
405 * @prepare_desc: Optional function to prepare the allocated MSI descriptor
407 * @set_desc: Set the msi descriptor for an interrupt
408 * @domain_alloc_irqs: Optional function to override the default allocation
410 * @domain_free_irqs: Optional function to override the default free
412 * @msi_post_free: Optional function which is invoked after freeing
414 * @msi_translate: Optional translate callback to support the odd wire to
415 * MSI bridges, e.g. MBIGEN
417 * @get_hwirq, @msi_init and @msi_free are callbacks used by the underlying
420 * @msi_check, @msi_prepare, @prepare_desc and @set_desc are callbacks used by the
421 * msi_domain_alloc/free_irqs*() variants.
423 * @domain_alloc_irqs, @domain_free_irqs can be used to override the
424 * default allocation/free functions (__msi_domain_alloc/free_irqs). This
425 * is initially for a wrapper around XENs seperate MSI universe which can't
426 * be wrapped into the regular irq domains concepts by mere mortals. This
427 * allows to universally use msi_domain_alloc/free_irqs without having to
428 * special case XEN all over the place.
430 struct msi_domain_ops
{
431 irq_hw_number_t (*get_hwirq
)(struct msi_domain_info
*info
,
432 msi_alloc_info_t
*arg
);
433 int (*msi_init
)(struct irq_domain
*domain
,
434 struct msi_domain_info
*info
,
435 unsigned int virq
, irq_hw_number_t hwirq
,
436 msi_alloc_info_t
*arg
);
437 void (*msi_free
)(struct irq_domain
*domain
,
438 struct msi_domain_info
*info
,
440 int (*msi_prepare
)(struct irq_domain
*domain
,
441 struct device
*dev
, int nvec
,
442 msi_alloc_info_t
*arg
);
443 void (*prepare_desc
)(struct irq_domain
*domain
, msi_alloc_info_t
*arg
,
444 struct msi_desc
*desc
);
445 void (*set_desc
)(msi_alloc_info_t
*arg
,
446 struct msi_desc
*desc
);
447 int (*domain_alloc_irqs
)(struct irq_domain
*domain
,
448 struct device
*dev
, int nvec
);
449 void (*domain_free_irqs
)(struct irq_domain
*domain
,
451 void (*msi_post_free
)(struct irq_domain
*domain
,
453 int (*msi_translate
)(struct irq_domain
*domain
, struct irq_fwspec
*fwspec
,
454 irq_hw_number_t
*hwirq
, unsigned int *type
);
458 * struct msi_domain_info - MSI interrupt domain data
459 * @flags: Flags to decribe features and capabilities
460 * @bus_token: The domain bus token
461 * @hwsize: The hardware table size or the software index limit.
462 * If 0 then the size is considered unlimited and
463 * gets initialized to the maximum software index limit
464 * by the domain creation code.
465 * @ops: The callback data structure
466 * @chip: Optional: associated interrupt chip
467 * @chip_data: Optional: associated interrupt chip data
468 * @handler: Optional: associated interrupt flow handler
469 * @handler_data: Optional: associated interrupt flow handler data
470 * @handler_name: Optional: associated interrupt flow handler name
471 * @data: Optional: domain specific data
473 struct msi_domain_info
{
475 enum irq_domain_bus_token bus_token
;
477 struct msi_domain_ops
*ops
;
478 struct irq_chip
*chip
;
480 irq_flow_handler_t handler
;
482 const char *handler_name
;
487 * struct msi_domain_template - Template for MSI device domains
488 * @name: Storage for the resulting name. Filled in by the core.
489 * @chip: Interrupt chip for this domain
490 * @ops: MSI domain ops
491 * @info: MSI domain info data
493 struct msi_domain_template
{
495 struct irq_chip chip
;
496 struct msi_domain_ops ops
;
497 struct msi_domain_info info
;
501 * Flags for msi_domain_info
503 * Bit 0-15: Generic MSI functionality which is not subject to restriction
506 * Bit 16-31: Functionality which depends on the underlying parent domain and
507 * can be masked out by msi_parent_ops::init_dev_msi_info() when
508 * a device MSI domain is initialized.
512 * Init non implemented ops callbacks with default MSI domain
515 MSI_FLAG_USE_DEF_DOM_OPS
= (1 << 0),
517 * Init non implemented chip callbacks with default MSI chip
520 MSI_FLAG_USE_DEF_CHIP_OPS
= (1 << 1),
521 /* Needs early activate, required for PCI */
522 MSI_FLAG_ACTIVATE_EARLY
= (1 << 2),
524 * Must reactivate when irq is started even when
525 * MSI_FLAG_ACTIVATE_EARLY has been set.
527 MSI_FLAG_MUST_REACTIVATE
= (1 << 3),
528 /* Populate sysfs on alloc() and destroy it on free() */
529 MSI_FLAG_DEV_SYSFS
= (1 << 4),
530 /* Allocate simple MSI descriptors */
531 MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS
= (1 << 5),
532 /* Free MSI descriptors */
533 MSI_FLAG_FREE_MSI_DESCS
= (1 << 6),
534 /* Use dev->fwnode for MSI device domain creation */
535 MSI_FLAG_USE_DEV_FWNODE
= (1 << 7),
536 /* Set parent->dev into domain->pm_dev on device domain creation */
537 MSI_FLAG_PARENT_PM_DEV
= (1 << 8),
538 /* Support for parent mask/unmask */
539 MSI_FLAG_PCI_MSI_MASK_PARENT
= (1 << 9),
541 /* Mask for the generic functionality */
542 MSI_GENERIC_FLAGS_MASK
= GENMASK(15, 0),
544 /* Mask for the domain specific functionality */
545 MSI_DOMAIN_FLAGS_MASK
= GENMASK(31, 16),
547 /* Support multiple PCI MSI interrupts */
548 MSI_FLAG_MULTI_PCI_MSI
= (1 << 16),
549 /* Support PCI MSIX interrupts */
550 MSI_FLAG_PCI_MSIX
= (1 << 17),
551 /* Is level-triggered capable, using two messages */
552 MSI_FLAG_LEVEL_CAPABLE
= (1 << 18),
553 /* MSI-X entries must be contiguous */
554 MSI_FLAG_MSIX_CONTIGUOUS
= (1 << 19),
555 /* PCI/MSI-X vectors can be dynamically allocated/freed post MSI-X enable */
556 MSI_FLAG_PCI_MSIX_ALLOC_DYN
= (1 << 20),
557 /* PCI MSIs cannot be steered separately to CPU cores */
558 MSI_FLAG_NO_AFFINITY
= (1 << 21),
562 * struct msi_parent_ops - MSI parent domain callbacks and configuration info
564 * @supported_flags: Required: The supported MSI flags of the parent domain
565 * @required_flags: Optional: The required MSI flags of the parent MSI domain
566 * @bus_select_token: Optional: The bus token of the real parent domain for
567 * irq_domain::select()
568 * @bus_select_mask: Optional: A mask of supported BUS_DOMAINs for
569 * irq_domain::select()
570 * @prefix: Optional: Prefix for the domain and chip name
571 * @init_dev_msi_info: Required: Callback for MSI parent domains to setup parent
572 * domain specific domain flags, domain ops and interrupt chip
573 * callbacks when a per device domain is created.
575 struct msi_parent_ops
{
578 u32 bus_select_token
;
581 bool (*init_dev_msi_info
)(struct device
*dev
, struct irq_domain
*domain
,
582 struct irq_domain
*msi_parent_domain
,
583 struct msi_domain_info
*msi_child_info
);
586 bool msi_parent_init_dev_msi_info(struct device
*dev
, struct irq_domain
*domain
,
587 struct irq_domain
*msi_parent_domain
,
588 struct msi_domain_info
*msi_child_info
);
590 int msi_domain_set_affinity(struct irq_data
*data
, const struct cpumask
*mask
,
593 struct irq_domain
*msi_create_irq_domain(struct fwnode_handle
*fwnode
,
594 struct msi_domain_info
*info
,
595 struct irq_domain
*parent
);
597 bool msi_create_device_irq_domain(struct device
*dev
, unsigned int domid
,
598 const struct msi_domain_template
*template,
599 unsigned int hwsize
, void *domain_data
,
601 void msi_remove_device_irq_domain(struct device
*dev
, unsigned int domid
);
603 bool msi_match_device_irq_domain(struct device
*dev
, unsigned int domid
,
604 enum irq_domain_bus_token bus_token
);
606 int msi_domain_alloc_irqs_range_locked(struct device
*dev
, unsigned int domid
,
607 unsigned int first
, unsigned int last
);
608 int msi_domain_alloc_irqs_range(struct device
*dev
, unsigned int domid
,
609 unsigned int first
, unsigned int last
);
610 int msi_domain_alloc_irqs_all_locked(struct device
*dev
, unsigned int domid
, int nirqs
);
612 struct msi_map
msi_domain_alloc_irq_at(struct device
*dev
, unsigned int domid
, unsigned int index
,
613 const struct irq_affinity_desc
*affdesc
,
614 union msi_instance_cookie
*cookie
);
616 void msi_domain_free_irqs_range_locked(struct device
*dev
, unsigned int domid
,
617 unsigned int first
, unsigned int last
);
618 void msi_domain_free_irqs_range(struct device
*dev
, unsigned int domid
,
619 unsigned int first
, unsigned int last
);
620 void msi_domain_free_irqs_all_locked(struct device
*dev
, unsigned int domid
);
621 void msi_domain_free_irqs_all(struct device
*dev
, unsigned int domid
);
623 struct msi_domain_info
*msi_get_domain_info(struct irq_domain
*domain
);
625 /* Per device platform MSI */
626 int platform_device_msi_init_and_alloc_irqs(struct device
*dev
, unsigned int nvec
,
627 irq_write_msi_msg_t write_msi_msg
);
628 void platform_device_msi_free_irqs_all(struct device
*dev
);
630 bool msi_device_has_isolated_msi(struct device
*dev
);
632 static inline int msi_domain_alloc_irqs(struct device
*dev
, unsigned int domid
, int nirqs
)
634 return msi_domain_alloc_irqs_range(dev
, domid
, 0, nirqs
- 1);
637 #else /* CONFIG_GENERIC_MSI_IRQ */
638 static inline bool msi_device_has_isolated_msi(struct device
*dev
)
641 * Arguably if the platform does not enable MSI support then it has
642 * "isolated MSI", as an interrupt controller that cannot receive MSIs
643 * is inherently isolated by our definition. The default definition for
644 * arch_is_isolated_msi() is conservative and returns false anyhow.
646 return arch_is_isolated_msi();
648 #endif /* CONFIG_GENERIC_MSI_IRQ */
650 /* PCI specific interfaces */
651 #ifdef CONFIG_PCI_MSI
652 struct pci_dev
*msi_desc_to_pci_dev(struct msi_desc
*desc
);
653 void pci_write_msi_msg(unsigned int irq
, struct msi_msg
*msg
);
654 void __pci_read_msi_msg(struct msi_desc
*entry
, struct msi_msg
*msg
);
655 void __pci_write_msi_msg(struct msi_desc
*entry
, struct msi_msg
*msg
);
656 void pci_msi_mask_irq(struct irq_data
*data
);
657 void pci_msi_unmask_irq(struct irq_data
*data
);
658 struct irq_domain
*pci_msi_create_irq_domain(struct fwnode_handle
*fwnode
,
659 struct msi_domain_info
*info
,
660 struct irq_domain
*parent
);
661 u32
pci_msi_domain_get_msi_rid(struct irq_domain
*domain
, struct pci_dev
*pdev
);
662 struct irq_domain
*pci_msi_get_device_domain(struct pci_dev
*pdev
);
663 #else /* CONFIG_PCI_MSI */
664 static inline struct irq_domain
*pci_msi_get_device_domain(struct pci_dev
*pdev
)
668 static inline void pci_write_msi_msg(unsigned int irq
, struct msi_msg
*msg
) { }
669 #endif /* !CONFIG_PCI_MSI */
671 #endif /* LINUX_MSI_H */