iomem.c

  1/* SPDX-License-Identifier: GPL-2.0 */
  2#include <linux/device.h>
  3#include <linux/types.h>
  4#include <linux/io.h>
  5#include <linux/mm.h>
  6#include <linux/ioremap.h>
  7
  8#ifndef arch_memremap_wb
  9static void *arch_memremap_wb(resource_size_t offset, unsigned long size,
 10			      unsigned long flags)
 11{
 12#ifdef ioremap_cache
 13	return (__force void *)ioremap_cache(offset, size);
 14#else
 15	return (__force void *)ioremap(offset, size);
 16#endif
 17}
 18#endif
 19
 20#ifndef arch_memremap_can_ram_remap
 21static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
 22					unsigned long flags)
 23{
 24	return true;
 25}
 26#endif
 27
 28static void *try_ram_remap(resource_size_t offset, size_t size,
 29			   unsigned long flags)
 30{
 31	unsigned long pfn = PHYS_PFN(offset);
 32
 33	/* In the simple case just return the existing linear address */
 34	if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
 35	    arch_memremap_can_ram_remap(offset, size, flags))
 36		return __va(offset);
 37
 38	return NULL; /* fallback to arch_memremap_wb */
 39}
 40
 41/**
 42 * memremap() - remap an iomem_resource as cacheable memory
 43 * @offset: iomem resource start address
 44 * @size: size of remap
 45 * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
 46 *		  MEMREMAP_ENC, MEMREMAP_DEC
 47 *
 48 * memremap() is "ioremap" for cases where it is known that the resource
 49 * being mapped does not have i/o side effects and the __iomem
 50 * annotation is not applicable. In the case of multiple flags, the different
 51 * mapping types will be attempted in the order listed below until one of
 52 * them succeeds.
 53 *
 54 * MEMREMAP_WB - matches the default mapping for System RAM on
 55 * the architecture.  This is usually a read-allocate write-back cache.
 56 * Moreover, if MEMREMAP_WB is specified and the requested remap region is RAM
 57 * memremap() will bypass establishing a new mapping and instead return
 58 * a pointer into the direct map.
 59 *
 60 * MEMREMAP_WT - establish a mapping whereby writes either bypass the
 61 * cache or are written through to memory and never exist in a
 62 * cache-dirty state with respect to program visibility.  Attempts to
 63 * map System RAM with this mapping type will fail.
 64 *
 65 * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
 66 * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
 67 * uncached. Attempts to map System RAM with this mapping type will fail.
 68 */
 69void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 70{
 71	int is_ram = region_intersects(offset, size,
 72				       IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 73	void *addr = NULL;
 74
 75	if (!flags)
 76		return NULL;
 77
 78	if (is_ram == REGION_MIXED) {
 79		WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
 80				&offset, (unsigned long) size);
 81		return NULL;
 82	}
 83
 84	/* Try all mapping types requested until one returns non-NULL */
 85	if (flags & MEMREMAP_WB) {
 86		/*
 87		 * MEMREMAP_WB is special in that it can be satisfied
 88		 * from the direct map.  Some archs depend on the
 89		 * capability of memremap() to autodetect cases where
 90		 * the requested range is potentially in System RAM.
 91		 */
 92		if (is_ram == REGION_INTERSECTS)
 93			addr = try_ram_remap(offset, size, flags);
 94		if (!addr)
 95			addr = arch_memremap_wb(offset, size, flags);
 96	}
 97
 98	/*
 99	 * If we don't have a mapping yet and other request flags are
100	 * present then we will be attempting to establish a new virtual
101	 * address mapping.  Enforce that this mapping is not aliasing
102	 * System RAM.
103	 */
104	if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
105		WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
106				&offset, (unsigned long) size);
107		return NULL;
108	}
109
110	if (!addr && (flags & MEMREMAP_WT))
111		addr = ioremap_wt(offset, size);
112
113	if (!addr && (flags & MEMREMAP_WC))
114		addr = ioremap_wc(offset, size);
115
116	return addr;
117}
118EXPORT_SYMBOL(memremap);
119
120void memunmap(void *addr)
121{
122	if (is_ioremap_addr(addr))
123		iounmap((void __iomem *) addr);
124}
125EXPORT_SYMBOL(memunmap);
126
127static void devm_memremap_release(struct device *dev, void *res)
128{
129	memunmap(*(void **)res);
130}
131
132static int devm_memremap_match(struct device *dev, void *res, void *match_data)
133{
134	return *(void **)res == match_data;
135}
136
137void *devm_memremap(struct device *dev, resource_size_t offset,
138		size_t size, unsigned long flags)
139{
140	void **ptr, *addr;
141
142	ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
143			dev_to_node(dev));
144	if (!ptr)
145		return ERR_PTR(-ENOMEM);
146
147	addr = memremap(offset, size, flags);
148	if (addr) {
149		*ptr = addr;
150		devres_add(dev, ptr);
151	} else {
152		devres_free(ptr);
153		return ERR_PTR(-ENXIO);
154	}
155
156	return addr;
157}
158EXPORT_SYMBOL(devm_memremap);
159
160void devm_memunmap(struct device *dev, void *addr)
161{
162	WARN_ON(devres_release(dev, devm_memremap_release,
163				devm_memremap_match, addr));
164}
165EXPORT_SYMBOL(devm_memunmap);