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