cregit-Linux how code gets into the kernel

Release 4.18 kernel/iomem.c

Directory: kernel
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/device.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/mm.h>

#ifndef ioremap_cache
/* temporary while we convert existing ioremap_cache users to memremap */

__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size) { return ioremap(offset, size); }

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#endif #ifndef arch_memremap_wb
static void *arch_memremap_wb(resource_size_t offset, unsigned long size) { return (__force void *)ioremap_cache(offset, size); }

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#endif #ifndef arch_memremap_can_ram_remap
static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, unsigned long flags) { return true; }

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#endif
static void *try_ram_remap(resource_size_t offset, size_t size, unsigned long flags) { unsigned long pfn = PHYS_PFN(offset); /* In the simple case just return the existing linear address */ if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) && arch_memremap_can_ram_remap(offset, size, flags)) return __va(offset); return NULL; /* fallback to arch_memremap_wb */ }

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/** * memremap() - remap an iomem_resource as cacheable memory * @offset: iomem resource start address * @size: size of remap * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC, * MEMREMAP_ENC, MEMREMAP_DEC * * memremap() is "ioremap" for cases where it is known that the resource * being mapped does not have i/o side effects and the __iomem * annotation is not applicable. In the case of multiple flags, the different * mapping types will be attempted in the order listed below until one of * them succeeds. * * MEMREMAP_WB - matches the default mapping for System RAM on * the architecture. This is usually a read-allocate write-back cache. * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM * memremap() will bypass establishing a new mapping and instead return * a pointer into the direct map. * * MEMREMAP_WT - establish a mapping whereby writes either bypass the * cache or are written through to memory and never exist in a * cache-dirty state with respect to program visibility. Attempts to * map System RAM with this mapping type will fail. * * MEMREMAP_WC - establish a writecombine mapping, whereby writes may * be coalesced together (e.g. in the CPU's write buffers), but is otherwise * uncached. Attempts to map System RAM with this mapping type will fail. */
void *memremap(resource_size_t offset, size_t size, unsigned long flags) { int is_ram = region_intersects(offset, size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); void *addr = NULL; if (!flags) return NULL; if (is_ram == REGION_MIXED) { WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n", &offset, (unsigned long) size); return NULL; } /* Try all mapping types requested until one returns non-NULL */ if (flags & MEMREMAP_WB) { /* * MEMREMAP_WB is special in that it can be satisifed * from the direct map. Some archs depend on the * capability of memremap() to autodetect cases where * the requested range is potentially in System RAM. */ if (is_ram == REGION_INTERSECTS) addr = try_ram_remap(offset, size, flags); if (!addr) addr = arch_memremap_wb(offset, size); } /* * If we don't have a mapping yet and other request flags are * present then we will be attempting to establish a new virtual * address mapping. Enforce that this mapping is not aliasing * System RAM. */ if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) { WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n", &offset, (unsigned long) size); return NULL; } if (!addr && (flags & MEMREMAP_WT)) addr = ioremap_wt(offset, size); if (!addr && (flags & MEMREMAP_WC)) addr = ioremap_wc(offset, size); return addr; }

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EXPORT_SYMBOL(memremap);
void memunmap(void *addr) { if (is_vmalloc_addr(addr)) iounmap((void __iomem *) addr); }

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EXPORT_SYMBOL(memunmap);
static void devm_memremap_release(struct device *dev, void *res) { memunmap(*(void **)res); }

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static int devm_memremap_match(struct device *dev, void *res, void *match_data) { return *(void **)res == match_data; }

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void *devm_memremap(struct device *dev, resource_size_t offset, size_t size, unsigned long flags) { void **ptr, *addr; ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL, dev_to_node(dev)); if (!ptr) return ERR_PTR(-ENOMEM); addr = memremap(offset, size, flags); if (addr) { *ptr = addr; devres_add(dev, ptr); } else { devres_free(ptr); return ERR_PTR(-ENXIO); } return addr; }

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Dan J Williams108100.00%1100.00%
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EXPORT_SYMBOL(devm_memremap);
void devm_memunmap(struct device *dev, void *addr) { WARN_ON(devres_release(dev, devm_memremap_release, devm_memremap_match, addr)); }

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EXPORT_SYMBOL(devm_memunmap);

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Directory: kernel
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