pci-p2pdma.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * PCI Peer 2 Peer DMA support.
  4 *
  5 * Copyright (c) 2016-2018, Logan Gunthorpe
  6 * Copyright (c) 2016-2017, Microsemi Corporation
  7 * Copyright (c) 2017, Christoph Hellwig
  8 * Copyright (c) 2018, Eideticom Inc.
  9 */
 10
 11#ifndef _LINUX_PCI_P2PDMA_H
 12#define _LINUX_PCI_P2PDMA_H
 13
 14#include <linux/pci.h>
 15
 16struct block_device;
 17struct scatterlist;
 18
 19/**
 20 * struct p2pdma_provider
 21 *
 22 * A p2pdma provider is a range of MMIO address space available to the CPU.
 23 */
 24struct p2pdma_provider {
 25	struct device *owner;
 26	u64 bus_offset;
 27};
 28
 29enum pci_p2pdma_map_type {
 30	/*
 31	 * PCI_P2PDMA_MAP_UNKNOWN: Used internally as an initial state before
 32	 * the mapping type has been calculated. Exported routines for the API
 33	 * will never return this value.
 34	 */
 35	PCI_P2PDMA_MAP_UNKNOWN = 0,
 36
 37	/*
 38	 * Not a PCI P2PDMA transfer.
 39	 */
 40	PCI_P2PDMA_MAP_NONE,
 41
 42	/*
 43	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
 44	 * traverse the host bridge and the host bridge is not in the
 45	 * allowlist. DMA Mapping routines should return an error when
 46	 * this is returned.
 47	 */
 48	PCI_P2PDMA_MAP_NOT_SUPPORTED,
 49
 50	/*
 51	 * PCI_P2PDMA_MAP_BUS_ADDR: Indicates that two devices can talk to
 52	 * each other directly through a PCI switch and the transaction will
 53	 * not traverse the host bridge. Such a mapping should program
 54	 * the DMA engine with PCI bus addresses.
 55	 */
 56	PCI_P2PDMA_MAP_BUS_ADDR,
 57
 58	/*
 59	 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
 60	 * to each other, but the transaction traverses a host bridge on the
 61	 * allowlist. In this case, a normal mapping either with CPU physical
 62	 * addresses (in the case of dma-direct) or IOVA addresses (in the
 63	 * case of IOMMUs) should be used to program the DMA engine.
 64	 */
 65	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
 66};
 67
 68#ifdef CONFIG_PCI_P2PDMA
 69int pcim_p2pdma_init(struct pci_dev *pdev);
 70struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar);
 71int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
 72		u64 offset);
 73int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
 74			     int num_clients, bool verbose);
 75struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients);
 76void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size);
 77void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size);
 78pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr);
 79struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
 80					 unsigned int *nents, u32 length);
 81void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl);
 82void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
 83int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
 84			    bool *use_p2pdma);
 85ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
 86			       bool use_p2pdma);
 87enum pci_p2pdma_map_type pci_p2pdma_map_type(struct p2pdma_provider *provider,
 88					     struct device *dev);
 89#else /* CONFIG_PCI_P2PDMA */
 90static inline int pcim_p2pdma_init(struct pci_dev *pdev)
 91{
 92	return -EOPNOTSUPP;
 93}
 94static inline struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev,
 95							   int bar)
 96{
 97	return NULL;
 98}
 99static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar,
100		size_t size, u64 offset)
101{
102	return -EOPNOTSUPP;
103}
104static inline int pci_p2pdma_distance_many(struct pci_dev *provider,
105	struct device **clients, int num_clients, bool verbose)
106{
107	return -1;
108}
109static inline struct pci_dev *pci_p2pmem_find_many(struct device **clients,
110						   int num_clients)
111{
112	return NULL;
113}
114static inline void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
115{
116	return NULL;
117}
118static inline void pci_free_p2pmem(struct pci_dev *pdev, void *addr,
119		size_t size)
120{
121}
122static inline pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev,
123						    void *addr)
124{
125	return 0;
126}
127static inline struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
128		unsigned int *nents, u32 length)
129{
130	return NULL;
131}
132static inline void pci_p2pmem_free_sgl(struct pci_dev *pdev,
133		struct scatterlist *sgl)
134{
135}
136static inline void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
137{
138}
139static inline int pci_p2pdma_enable_store(const char *page,
140		struct pci_dev **p2p_dev, bool *use_p2pdma)
141{
142	*use_p2pdma = false;
143	return 0;
144}
145static inline ssize_t pci_p2pdma_enable_show(char *page,
146		struct pci_dev *p2p_dev, bool use_p2pdma)
147{
148	return sprintf(page, "none\n");
149}
150static inline enum pci_p2pdma_map_type
151pci_p2pdma_map_type(struct p2pdma_provider *provider, struct device *dev)
152{
153	return PCI_P2PDMA_MAP_NOT_SUPPORTED;
154}
155#endif /* CONFIG_PCI_P2PDMA */
156
157
158static inline int pci_p2pdma_distance(struct pci_dev *provider,
159	struct device *client, bool verbose)
160{
161	return pci_p2pdma_distance_many(provider, &client, 1, verbose);
162}
163
164static inline struct pci_dev *pci_p2pmem_find(struct device *client)
165{
166	return pci_p2pmem_find_many(&client, 1);
167}
168
169struct pci_p2pdma_map_state {
170	struct p2pdma_provider *mem;
171	enum pci_p2pdma_map_type map;
172};
173
174
175/* helper for pci_p2pdma_state(), do not use directly */
176void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
177		struct device *dev, struct page *page);
178
179/**
180 * pci_p2pdma_state - check the P2P transfer state of a page
181 * @state:	P2P state structure
182 * @dev:	device to transfer to/from
183 * @page:	page to map
184 *
185 * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
186 * map type, and updates @state with all information needed for a P2P transfer.
187 */
188static inline enum pci_p2pdma_map_type
189pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
190		struct page *page)
191{
192	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
193		__pci_p2pdma_update_state(state, dev, page);
194		return state->map;
195	}
196	return PCI_P2PDMA_MAP_NONE;
197}
198
199/**
200 * pci_p2pdma_bus_addr_map - Translate a physical address to a bus address
201 *			     for a PCI_P2PDMA_MAP_BUS_ADDR transfer.
202 * @provider:	P2P provider structure
203 * @paddr:	physical address to map
204 *
205 * Map a physically contiguous PCI_P2PDMA_MAP_BUS_ADDR transfer.
206 */
207static inline dma_addr_t
208pci_p2pdma_bus_addr_map(struct p2pdma_provider *provider, phys_addr_t paddr)
209{
210	return paddr + provider->bus_offset;
211}
212
213#endif /* _LINUX_PCI_P2P_H */