io-mapping.h

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Copyright © 2008 Keith Packard <keithp@keithp.com>
  4 */
  5
  6#ifndef _LINUX_IO_MAPPING_H
  7#define _LINUX_IO_MAPPING_H
  8
  9#include <linux/types.h>
 10#include <linux/slab.h>
 11#include <linux/bug.h>
 12#include <linux/io.h>
 13#include <linux/pgtable.h>
 14#include <asm/page.h>
 15
 16/*
 17 * The io_mapping mechanism provides an abstraction for mapping
 18 * individual pages from an io device to the CPU in an efficient fashion.
 19 *
 20 * See Documentation/driver-api/io-mapping.rst
 21 */
 22
 23struct io_mapping {
 24	resource_size_t base;
 25	unsigned long size;
 26	pgprot_t prot;
 27	void __iomem *iomem;
 28};
 29
 30#ifdef CONFIG_HAVE_ATOMIC_IOMAP
 31
 32#include <linux/pfn.h>
 33#include <asm/iomap.h>
 34/*
 35 * For small address space machines, mapping large objects
 36 * into the kernel virtual space isn't practical. Where
 37 * available, use fixmap support to dynamically map pages
 38 * of the object at run time.
 39 */
 40
 41static inline struct io_mapping *
 42io_mapping_init_wc(struct io_mapping *iomap,
 43		   resource_size_t base,
 44		   unsigned long size)
 45{
 46	pgprot_t prot;
 47
 48	if (iomap_create_wc(base, size, &prot))
 49		return NULL;
 50
 51	iomap->base = base;
 52	iomap->size = size;
 53	iomap->prot = prot;
 54	return iomap;
 55}
 56
 57static inline void
 58io_mapping_fini(struct io_mapping *mapping)
 59{
 60	iomap_free(mapping->base, mapping->size);
 61}
 62
 63/* Atomic map/unmap */
 64static inline void __iomem *
 65io_mapping_map_atomic_wc(struct io_mapping *mapping,
 66			 unsigned long offset)
 67{
 68	resource_size_t phys_addr;
 69
 70	BUG_ON(offset >= mapping->size);
 71	phys_addr = mapping->base + offset;
 72	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 73		preempt_disable();
 74	else
 75		migrate_disable();
 76	pagefault_disable();
 77	return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
 78}
 79
 80static inline void
 81io_mapping_unmap_atomic(void __iomem *vaddr)
 82{
 83	kunmap_local_indexed((void __force *)vaddr);
 84	pagefault_enable();
 85	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 86		preempt_enable();
 87	else
 88		migrate_enable();
 89}
 90
 91static inline void __iomem *
 92io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
 93{
 94	resource_size_t phys_addr;
 95
 96	BUG_ON(offset >= mapping->size);
 97	phys_addr = mapping->base + offset;
 98	return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
 99}
100
101static inline void io_mapping_unmap_local(void __iomem *vaddr)
102{
103	kunmap_local_indexed((void __force *)vaddr);
104}
105
106static inline void __iomem *
107io_mapping_map_wc(struct io_mapping *mapping,
108		  unsigned long offset,
109		  unsigned long size)
110{
111	resource_size_t phys_addr;
112
113	BUG_ON(offset >= mapping->size);
114	phys_addr = mapping->base + offset;
115
116	return ioremap_wc(phys_addr, size);
117}
118
119static inline void
120io_mapping_unmap(void __iomem *vaddr)
121{
122	iounmap(vaddr);
123}
124
125#else  /* HAVE_ATOMIC_IOMAP */
126
127#include <linux/uaccess.h>
128
129/* Create the io_mapping object*/
130static inline struct io_mapping *
131io_mapping_init_wc(struct io_mapping *iomap,
132		   resource_size_t base,
133		   unsigned long size)
134{
135	iomap->iomem = ioremap_wc(base, size);
136	if (!iomap->iomem)
137		return NULL;
138
139	iomap->base = base;
140	iomap->size = size;
141	iomap->prot = pgprot_writecombine(PAGE_KERNEL);
142
143	return iomap;
144}
145
146static inline void
147io_mapping_fini(struct io_mapping *mapping)
148{
149	iounmap(mapping->iomem);
150}
151
152/* Non-atomic map/unmap */
153static inline void __iomem *
154io_mapping_map_wc(struct io_mapping *mapping,
155		  unsigned long offset,
156		  unsigned long size)
157{
158	return mapping->iomem + offset;
159}
160
161static inline void
162io_mapping_unmap(void __iomem *vaddr)
163{
164}
165
166/* Atomic map/unmap */
167static inline void __iomem *
168io_mapping_map_atomic_wc(struct io_mapping *mapping,
169			 unsigned long offset)
170{
171	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
172		preempt_disable();
173	else
174		migrate_disable();
175	pagefault_disable();
176	return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
177}
178
179static inline void
180io_mapping_unmap_atomic(void __iomem *vaddr)
181{
182	io_mapping_unmap(vaddr);
183	pagefault_enable();
184	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
185		preempt_enable();
186	else
187		migrate_enable();
188}
189
190static inline void __iomem *
191io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
192{
193	return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
194}
195
196static inline void io_mapping_unmap_local(void __iomem *vaddr)
197{
198	io_mapping_unmap(vaddr);
199}
200
201#endif /* !HAVE_ATOMIC_IOMAP */
202
203static inline struct io_mapping *
204io_mapping_create_wc(resource_size_t base,
205		     unsigned long size)
206{
207	struct io_mapping *iomap;
208
209	iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
210	if (!iomap)
211		return NULL;
212
213	if (!io_mapping_init_wc(iomap, base, size)) {
214		kfree(iomap);
215		return NULL;
216	}
217
218	return iomap;
219}
220
221static inline void
222io_mapping_free(struct io_mapping *iomap)
223{
224	io_mapping_fini(iomap);
225	kfree(iomap);
226}
227
228#endif /* _LINUX_IO_MAPPING_H */