diff options
Diffstat (limited to 'Documentation/core-api')
-rw-r--r-- | Documentation/core-api/dma-api.rst | 88 | ||||
-rw-r--r-- | Documentation/core-api/irq/irq-domain.rst | 22 | ||||
-rw-r--r-- | Documentation/core-api/symbol-namespaces.rst | 26 |
3 files changed, 113 insertions, 23 deletions
diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst index e6d23f117308..00a1d4fa3f9e 100644 --- a/Documentation/core-api/dma-api.rst +++ b/Documentation/core-api/dma-api.rst @@ -565,6 +565,16 @@ dma_alloc_pages(). page must be the pointer returned by dma_alloc_pages(). :: + int + dma_mmap_pages(struct device *dev, struct vm_area_struct *vma, + size_t size, struct page *page) + +Map an allocation returned from dma_alloc_pages() into a user address space. +dev and size must be the same as those passed into dma_alloc_pages(). +page must be the pointer returned by dma_alloc_pages(). + +:: + void * dma_alloc_noncoherent(struct device *dev, size_t size, dma_addr_t *dma_handle, enum dma_data_direction dir, @@ -586,6 +596,84 @@ dma_alloc_noncoherent(). :: + struct sg_table * + dma_alloc_noncontiguous(struct device *dev, size_t size, + enum dma_data_direction dir, gfp_t gfp, + unsigned long attrs); + +This routine allocates <size> bytes of non-coherent and possibly non-contiguous +memory. It returns a pointer to struct sg_table that describes the allocated +and DMA mapped memory, or NULL if the allocation failed. The resulting memory +can be used for struct page mapped into a scatterlist are suitable for. + +The return sg_table is guaranteed to have 1 single DMA mapped segment as +indicated by sgt->nents, but it might have multiple CPU side segments as +indicated by sgt->orig_nents. + +The dir parameter specified if data is read and/or written by the device, +see dma_map_single() for details. + +The gfp parameter allows the caller to specify the ``GFP_`` flags (see +kmalloc()) for the allocation, but rejects flags used to specify a memory +zone such as GFP_DMA or GFP_HIGHMEM. + +The attrs argument must be either 0 or DMA_ATTR_ALLOC_SINGLE_PAGES. + +Before giving the memory to the device, dma_sync_sgtable_for_device() needs +to be called, and before reading memory written by the device, +dma_sync_sgtable_for_cpu(), just like for streaming DMA mappings that are +reused. + +:: + + void + dma_free_noncontiguous(struct device *dev, size_t size, + struct sg_table *sgt, + enum dma_data_direction dir) + +Free memory previously allocated using dma_alloc_noncontiguous(). dev, size, +and dir must all be the same as those passed into dma_alloc_noncontiguous(). +sgt must be the pointer returned by dma_alloc_noncontiguous(). + +:: + + void * + dma_vmap_noncontiguous(struct device *dev, size_t size, + struct sg_table *sgt) + +Return a contiguous kernel mapping for an allocation returned from +dma_alloc_noncontiguous(). dev and size must be the same as those passed into +dma_alloc_noncontiguous(). sgt must be the pointer returned by +dma_alloc_noncontiguous(). + +Once a non-contiguous allocation is mapped using this function, the +flush_kernel_vmap_range() and invalidate_kernel_vmap_range() APIs must be used +to manage the coherency between the kernel mapping, the device and user space +mappings (if any). + +:: + + void + dma_vunmap_noncontiguous(struct device *dev, void *vaddr) + +Unmap a kernel mapping returned by dma_vmap_noncontiguous(). dev must be the +same the one passed into dma_alloc_noncontiguous(). vaddr must be the pointer +returned by dma_vmap_noncontiguous(). + + +:: + + int + dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma, + size_t size, struct sg_table *sgt) + +Map an allocation returned from dma_alloc_noncontiguous() into a user address +space. dev and size must be the same as those passed into +dma_alloc_noncontiguous(). sgt must be the pointer returned by +dma_alloc_noncontiguous(). + +:: + int dma_get_cache_alignment(void) diff --git a/Documentation/core-api/irq/irq-domain.rst b/Documentation/core-api/irq/irq-domain.rst index a77c24c27f7b..8214e215a8bf 100644 --- a/Documentation/core-api/irq/irq-domain.rst +++ b/Documentation/core-api/irq/irq-domain.rst @@ -42,10 +42,10 @@ irq_domain usage ================ An interrupt controller driver creates and registers an irq_domain by -calling one of the irq_domain_add_*() functions (each mapping method -has a different allocator function, more on that later). The function -will return a pointer to the irq_domain on success. The caller must -provide the allocator function with an irq_domain_ops structure. +calling one of the irq_domain_add_*() or irq_domain_create_*() functions +(each mapping method has a different allocator function, more on that later). +The function will return a pointer to the irq_domain on success. The caller +must provide the allocator function with an irq_domain_ops structure. In most cases, the irq_domain will begin empty without any mappings between hwirq and IRQ numbers. Mappings are added to the irq_domain @@ -147,6 +147,7 @@ Legacy irq_domain_add_simple() irq_domain_add_legacy() irq_domain_add_legacy_isa() + irq_domain_create_simple() irq_domain_create_legacy() The Legacy mapping is a special case for drivers that already have a @@ -169,13 +170,13 @@ supported. For example, ISA controllers would use the legacy map for mapping Linux IRQs 0-15 so that existing ISA drivers get the correct IRQ numbers. -Most users of legacy mappings should use irq_domain_add_simple() which -will use a legacy domain only if an IRQ range is supplied by the -system and will otherwise use a linear domain mapping. The semantics -of this call are such that if an IRQ range is specified then +Most users of legacy mappings should use irq_domain_add_simple() or +irq_domain_create_simple() which will use a legacy domain only if an IRQ range +is supplied by the system and will otherwise use a linear domain mapping. +The semantics of this call are such that if an IRQ range is specified then descriptors will be allocated on-the-fly for it, and if no range is -specified it will fall through to irq_domain_add_linear() which means -*no* irq descriptors will be allocated. +specified it will fall through to irq_domain_add_linear() or +irq_domain_create_linear() which means *no* irq descriptors will be allocated. A typical use case for simple domains is where an irqchip provider is supporting both dynamic and static IRQ assignments. @@ -186,6 +187,7 @@ that the driver using the simple domain call irq_create_mapping() before any irq_find_mapping() since the latter will actually work for the static IRQ assignment case. +irq_domain_add_simple() and irq_domain_create_simple() as well as irq_domain_add_legacy() and irq_domain_create_legacy() are functionally equivalent, except for the first argument is different - the former accepts an Open Firmware specific 'struct device_node', while the latter diff --git a/Documentation/core-api/symbol-namespaces.rst b/Documentation/core-api/symbol-namespaces.rst index 9b76337f6756..5ad9e0abe42c 100644 --- a/Documentation/core-api/symbol-namespaces.rst +++ b/Documentation/core-api/symbol-namespaces.rst @@ -43,14 +43,14 @@ exporting of kernel symbols to the kernel symbol table, variants of these are available to export symbols into a certain namespace: EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL(). They take one additional argument: the namespace. Please note that due to macro expansion that argument needs to be a -preprocessor symbol. E.g. to export the symbol `usb_stor_suspend` into the -namespace `USB_STORAGE`, use:: +preprocessor symbol. E.g. to export the symbol ``usb_stor_suspend`` into the +namespace ``USB_STORAGE``, use:: EXPORT_SYMBOL_NS(usb_stor_suspend, USB_STORAGE); -The corresponding ksymtab entry struct `kernel_symbol` will have the member -`namespace` set accordingly. A symbol that is exported without a namespace will -refer to `NULL`. There is no default namespace if none is defined. `modpost` +The corresponding ksymtab entry struct ``kernel_symbol`` will have the member +``namespace`` set accordingly. A symbol that is exported without a namespace will +refer to ``NULL``. There is no default namespace if none is defined. ``modpost`` and kernel/module.c make use the namespace at build time or module load time, respectively. @@ -64,7 +64,7 @@ and EXPORT_SYMBOL_GPL() macro expansions that do not specify a namespace. There are multiple ways of specifying this define and it depends on the subsystem and the maintainer's preference, which one to use. The first option -is to define the default namespace in the `Makefile` of the subsystem. E.g. to +is to define the default namespace in the ``Makefile`` of the subsystem. E.g. to export all symbols defined in usb-common into the namespace USB_COMMON, add a line like this to drivers/usb/common/Makefile:: @@ -96,7 +96,7 @@ using a statement like:: MODULE_IMPORT_NS(USB_STORAGE); -This will create a `modinfo` tag in the module for each imported namespace. +This will create a ``modinfo`` tag in the module for each imported namespace. This has the side effect, that the imported namespaces of a module can be inspected with modinfo:: @@ -113,7 +113,7 @@ metadata definitions like MODULE_AUTHOR() or MODULE_LICENSE(). Refer to section 4. Loading Modules that use namespaced Symbols ============================================== -At module loading time (e.g. `insmod`), the kernel will check each symbol +At module loading time (e.g. ``insmod``), the kernel will check each symbol referenced from the module for its availability and whether the namespace it might be exported to has been imported by the module. The default behaviour of the kernel is to reject loading modules that don't specify sufficient imports. @@ -138,19 +138,19 @@ missing imports. Fixing missing imports can be done with:: A typical scenario for module authors would be:: - write code that depends on a symbol from a not imported namespace - - `make` + - ``make`` - notice the warning of modpost telling about a missing import - - run `make nsdeps` to add the import to the correct code location + - run ``make nsdeps`` to add the import to the correct code location For subsystem maintainers introducing a namespace, the steps are very similar. -Again, `make nsdeps` will eventually add the missing namespace imports for +Again, ``make nsdeps`` will eventually add the missing namespace imports for in-tree modules:: - move or add symbols to a namespace (e.g. with EXPORT_SYMBOL_NS()) - - `make` (preferably with an allmodconfig to cover all in-kernel + - ``make`` (preferably with an allmodconfig to cover all in-kernel modules) - notice the warning of modpost telling about a missing import - - run `make nsdeps` to add the import to the correct code location + - run ``make nsdeps`` to add the import to the correct code location You can also run nsdeps for external module builds. A typical usage is:: |