1// SPDX-License-Identifier: GPL-2.0
2/*
3 * PCI MSI/MSI-X — Exported APIs for device drivers
4 *
5 * Copyright (C) 2003-2004 Intel
6 * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
7 * Copyright (C) 2016 Christoph Hellwig.
8 * Copyright (C) 2022 Linutronix GmbH
9 */
10
11#include <linux/export.h>
12#include <linux/irq.h>
13
14#include "msi.h"
15
16/**
17 * pci_enable_msi() - Enable MSI interrupt mode on device
18 * @dev: the PCI device to operate on
19 *
20 * Legacy device driver API to enable MSI interrupts mode on device and
21 * allocate a single interrupt vector. On success, the allocated vector
22 * Linux IRQ will be saved at @dev->irq. The driver must invoke
23 * pci_disable_msi() on cleanup.
24 *
25 * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
26 * pair should, in general, be used instead.
27 *
28 * Return: 0 on success, errno otherwise
29 */
30int pci_enable_msi(struct pci_dev *dev)
31{
32 int rc = __pci_enable_msi_range(dev, minvec: 1, maxvec: 1, NULL);
33 if (rc < 0)
34 return rc;
35 return 0;
36}
37EXPORT_SYMBOL(pci_enable_msi);
38
39/**
40 * pci_disable_msi() - Disable MSI interrupt mode on device
41 * @dev: the PCI device to operate on
42 *
43 * Legacy device driver API to disable MSI interrupt mode on device,
44 * free earlier allocated interrupt vectors, and restore INTx emulation.
45 * The PCI device Linux IRQ (@dev->irq) is restored to its default
46 * pin-assertion IRQ. This is the cleanup pair of pci_enable_msi().
47 *
48 * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
49 * pair should, in general, be used instead.
50 */
51void pci_disable_msi(struct pci_dev *dev)
52{
53 if (!pci_msi_enabled() || !dev || !dev->msi_enabled)
54 return;
55
56 guard(msi_descs_lock)(l: &dev->dev);
57 pci_msi_shutdown(dev);
58 pci_free_msi_irqs(dev);
59}
60EXPORT_SYMBOL(pci_disable_msi);
61
62/**
63 * pci_msix_vec_count() - Get number of MSI-X interrupt vectors on device
64 * @dev: the PCI device to operate on
65 *
66 * Return: number of MSI-X interrupt vectors available on this device
67 * (i.e., the device's MSI-X capability structure "table size"), -EINVAL
68 * if the device is not MSI-X capable, other errnos otherwise.
69 */
70int pci_msix_vec_count(struct pci_dev *dev)
71{
72 u16 control;
73
74 if (!dev->msix_cap)
75 return -EINVAL;
76
77 pci_read_config_word(dev, where: dev->msix_cap + PCI_MSIX_FLAGS, val: &control);
78 return msix_table_size(control);
79}
80EXPORT_SYMBOL(pci_msix_vec_count);
81
82/**
83 * pci_enable_msix_range() - Enable MSI-X interrupt mode on device
84 * @dev: the PCI device to operate on
85 * @entries: input/output parameter, array of MSI-X configuration entries
86 * @minvec: minimum required number of MSI-X vectors
87 * @maxvec: maximum desired number of MSI-X vectors
88 *
89 * Legacy device driver API to enable MSI-X interrupt mode on device and
90 * configure its MSI-X capability structure as appropriate. The passed
91 * @entries array must have each of its members "entry" field set to a
92 * desired (valid) MSI-X vector number, where the range of valid MSI-X
93 * vector numbers can be queried through pci_msix_vec_count(). If
94 * successful, the driver must invoke pci_disable_msix() on cleanup.
95 *
96 * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
97 * pair should, in general, be used instead.
98 *
99 * Return: number of MSI-X vectors allocated (which might be smaller
100 * than @maxvecs), where Linux IRQ numbers for such allocated vectors
101 * are saved back in the @entries array elements' "vector" field. Return
102 * -ENOSPC if less than @minvecs interrupt vectors are available.
103 * Return -EINVAL if one of the passed @entries members "entry" field
104 * was invalid or a duplicate, or if plain MSI interrupts mode was
105 * earlier enabled on device. Return other errnos otherwise.
106 */
107int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
108 int minvec, int maxvec)
109{
110 return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, flags: 0);
111}
112EXPORT_SYMBOL(pci_enable_msix_range);
113
114/**
115 * pci_msix_can_alloc_dyn - Query whether dynamic allocation after enabling
116 * MSI-X is supported
117 *
118 * @dev: PCI device to operate on
119 *
120 * Return: True if supported, false otherwise
121 */
122bool pci_msix_can_alloc_dyn(struct pci_dev *dev)
123{
124 if (!dev->msix_cap)
125 return false;
126
127 return pci_msi_domain_supports(dev, feature_mask: MSI_FLAG_PCI_MSIX_ALLOC_DYN, mode: DENY_LEGACY);
128}
129EXPORT_SYMBOL_GPL(pci_msix_can_alloc_dyn);
130
131/**
132 * pci_msix_alloc_irq_at - Allocate an MSI-X interrupt after enabling MSI-X
133 * at a given MSI-X vector index or any free vector index
134 *
135 * @dev: PCI device to operate on
136 * @index: Index to allocate. If @index == MSI_ANY_INDEX this allocates
137 * the next free index in the MSI-X table
138 * @affdesc: Optional pointer to an affinity descriptor structure. NULL otherwise
139 *
140 * Return: A struct msi_map
141 *
142 * On success msi_map::index contains the allocated index (>= 0) and
143 * msi_map::virq contains the allocated Linux interrupt number (> 0).
144 *
145 * On fail msi_map::index contains the error code and msi_map::virq
146 * is set to 0.
147 */
148struct msi_map pci_msix_alloc_irq_at(struct pci_dev *dev, unsigned int index,
149 const struct irq_affinity_desc *affdesc)
150{
151 struct msi_map map = { .index = -ENOTSUPP };
152
153 if (!dev->msix_enabled)
154 return map;
155
156 if (!pci_msix_can_alloc_dyn(dev))
157 return map;
158
159 return msi_domain_alloc_irq_at(dev: &dev->dev, domid: MSI_DEFAULT_DOMAIN, index, affdesc, NULL);
160}
161EXPORT_SYMBOL_GPL(pci_msix_alloc_irq_at);
162
163/**
164 * pci_msix_free_irq - Free an interrupt on a PCI/MSI-X interrupt domain
165 *
166 * @dev: The PCI device to operate on
167 * @map: A struct msi_map describing the interrupt to free
168 *
169 * Undo an interrupt vector allocation. Does not disable MSI-X.
170 */
171void pci_msix_free_irq(struct pci_dev *dev, struct msi_map map)
172{
173 if (WARN_ON_ONCE(map.index < 0 || map.virq <= 0))
174 return;
175 if (WARN_ON_ONCE(!pci_msix_can_alloc_dyn(dev)))
176 return;
177 msi_domain_free_irqs_range(dev: &dev->dev, domid: MSI_DEFAULT_DOMAIN, first: map.index, last: map.index);
178}
179EXPORT_SYMBOL_GPL(pci_msix_free_irq);
180
181/**
182 * pci_disable_msix() - Disable MSI-X interrupt mode on device
183 * @dev: the PCI device to operate on
184 *
185 * Legacy device driver API to disable MSI-X interrupt mode on device,
186 * free earlier-allocated interrupt vectors, and restore INTx.
187 * The PCI device Linux IRQ (@dev->irq) is restored to its default pin
188 * assertion IRQ. This is the cleanup pair of pci_enable_msix_range().
189 *
190 * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
191 * pair should, in general, be used instead.
192 */
193void pci_disable_msix(struct pci_dev *dev)
194{
195 if (!pci_msi_enabled() || !dev || !dev->msix_enabled)
196 return;
197
198 guard(msi_descs_lock)(l: &dev->dev);
199 pci_msix_shutdown(dev);
200 pci_free_msi_irqs(dev);
201}
202EXPORT_SYMBOL(pci_disable_msix);
203
204/**
205 * pci_alloc_irq_vectors() - Allocate multiple device interrupt vectors
206 * @dev: the PCI device to operate on
207 * @min_vecs: minimum required number of vectors (must be >= 1)
208 * @max_vecs: maximum desired number of vectors
209 * @flags: One or more of:
210 *
211 * * %PCI_IRQ_MSIX Allow trying MSI-X vector allocations
212 * * %PCI_IRQ_MSI Allow trying MSI vector allocations
213 *
214 * * %PCI_IRQ_INTX Allow trying INTx interrupts, if and
215 * only if @min_vecs == 1
216 *
217 * * %PCI_IRQ_AFFINITY Auto-manage IRQs affinity by spreading
218 * the vectors around available CPUs
219 *
220 * Allocate up to @max_vecs interrupt vectors on device. MSI-X irq
221 * vector allocation has a higher precedence over plain MSI, which has a
222 * higher precedence over legacy INTx emulation.
223 *
224 * Upon a successful allocation, the caller should use pci_irq_vector()
225 * to get the Linux IRQ number to be passed to request_threaded_irq().
226 * The driver must call pci_free_irq_vectors() on cleanup.
227 *
228 * Return: number of allocated vectors (which might be smaller than
229 * @max_vecs), -ENOSPC if less than @min_vecs interrupt vectors are
230 * available, other errnos otherwise.
231 */
232int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
233 unsigned int max_vecs, unsigned int flags)
234{
235 return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs,
236 flags, NULL);
237}
238EXPORT_SYMBOL(pci_alloc_irq_vectors);
239
240/**
241 * pci_alloc_irq_vectors_affinity() - Allocate multiple device interrupt
242 * vectors with affinity requirements
243 * @dev: the PCI device to operate on
244 * @min_vecs: minimum required number of vectors (must be >= 1)
245 * @max_vecs: maximum desired number of vectors
246 * @flags: allocation flags, as in pci_alloc_irq_vectors()
247 * @affd: affinity requirements (can be %NULL).
248 *
249 * Same as pci_alloc_irq_vectors(), but with the extra @affd parameter.
250 * Check that function docs, and &struct irq_affinity, for more details.
251 */
252int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
253 unsigned int max_vecs, unsigned int flags,
254 struct irq_affinity *affd)
255{
256 struct irq_affinity msi_default_affd = {0};
257 int nvecs = -ENOSPC;
258
259 if (flags & PCI_IRQ_AFFINITY) {
260 if (!affd)
261 affd = &msi_default_affd;
262 } else {
263 if (WARN_ON(affd))
264 affd = NULL;
265 }
266
267 if (flags & PCI_IRQ_MSIX) {
268 nvecs = __pci_enable_msix_range(dev, NULL, minvec: min_vecs, maxvec: max_vecs,
269 affd, flags);
270 if (nvecs > 0)
271 return nvecs;
272 }
273
274 if (flags & PCI_IRQ_MSI) {
275 nvecs = __pci_enable_msi_range(dev, minvec: min_vecs, maxvec: max_vecs, affd);
276 if (nvecs > 0)
277 return nvecs;
278 }
279
280 /* use INTx IRQ if allowed */
281 if (flags & PCI_IRQ_INTX) {
282 if (min_vecs == 1 && dev->irq) {
283 /*
284 * Invoke the affinity spreading logic to ensure that
285 * the device driver can adjust queue configuration
286 * for the single interrupt case.
287 */
288 if (affd)
289 irq_create_affinity_masks(nvec: 1, affd);
290 pci_intx(dev, enable: 1);
291 return 1;
292 }
293 }
294
295 return nvecs;
296}
297EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);
298
299/**
300 * pci_irq_vector() - Get Linux IRQ number of a device interrupt vector
301 * @dev: the PCI device to operate on
302 * @nr: device-relative interrupt vector index (0-based); has different
303 * meanings, depending on interrupt mode:
304 *
305 * * MSI-X the index in the MSI-X vector table
306 * * MSI the index of the enabled MSI vectors
307 * * INTx must be 0
308 *
309 * Return: the Linux IRQ number, or -EINVAL if @nr is out of range
310 */
311int pci_irq_vector(struct pci_dev *dev, unsigned int nr)
312{
313 unsigned int irq;
314
315 if (!dev->msi_enabled && !dev->msix_enabled)
316 return !nr ? dev->irq : -EINVAL;
317
318 irq = msi_get_virq(dev: &dev->dev, index: nr);
319 return irq ? irq : -EINVAL;
320}
321EXPORT_SYMBOL(pci_irq_vector);
322
323/**
324 * pci_irq_get_affinity() - Get a device interrupt vector affinity
325 * @dev: the PCI device to operate on
326 * @nr: device-relative interrupt vector index (0-based); has different
327 * meanings, depending on interrupt mode:
328 *
329 * * MSI-X the index in the MSI-X vector table
330 * * MSI the index of the enabled MSI vectors
331 * * INTx must be 0
332 *
333 * Return: MSI/MSI-X vector affinity, NULL if @nr is out of range or if
334 * the MSI(-X) vector was allocated without explicit affinity
335 * requirements (e.g., by pci_enable_msi(), pci_enable_msix_range(), or
336 * pci_alloc_irq_vectors() without the %PCI_IRQ_AFFINITY flag). Return a
337 * generic set of CPU IDs representing all possible CPUs available
338 * during system boot if the device is in legacy INTx mode.
339 */
340const struct cpumask *pci_irq_get_affinity(struct pci_dev *dev, int nr)
341{
342 int idx, irq = pci_irq_vector(dev, nr);
343 struct msi_desc *desc;
344
345 if (WARN_ON_ONCE(irq <= 0))
346 return NULL;
347
348 desc = irq_get_msi_desc(irq);
349 /* Non-MSI does not have the information handy */
350 if (!desc)
351 return cpu_possible_mask;
352
353 /* MSI[X] interrupts can be allocated without affinity descriptor */
354 if (!desc->affinity)
355 return NULL;
356
357 /*
358 * MSI has a mask array in the descriptor.
359 * MSI-X has a single mask.
360 */
361 idx = dev->msi_enabled ? nr : 0;
362 return &desc->affinity[idx].mask;
363}
364EXPORT_SYMBOL(pci_irq_get_affinity);
365
366/**
367 * pci_free_irq_vectors() - Free previously allocated IRQs for a device
368 * @dev: the PCI device to operate on
369 *
370 * Undo the interrupt vector allocations and possible device MSI/MSI-X
371 * enablement earlier done through pci_alloc_irq_vectors_affinity() or
372 * pci_alloc_irq_vectors().
373 */
374void pci_free_irq_vectors(struct pci_dev *dev)
375{
376 pci_disable_msix(dev);
377 pci_disable_msi(dev);
378}
379EXPORT_SYMBOL(pci_free_irq_vectors);
380
381/**
382 * pci_restore_msi_state() - Restore cached MSI(-X) state on device
383 * @dev: the PCI device to operate on
384 *
385 * Write the Linux-cached MSI(-X) state back on device. This is
386 * typically useful upon system resume, or after an error-recovery PCI
387 * adapter reset.
388 */
389void pci_restore_msi_state(struct pci_dev *dev)
390{
391 __pci_restore_msi_state(dev);
392 __pci_restore_msix_state(dev);
393}
394EXPORT_SYMBOL_GPL(pci_restore_msi_state);
395
396/**
397 * pci_msi_enabled() - Are MSI(-X) interrupts enabled system-wide?
398 *
399 * Return: true if MSI has not been globally disabled through ACPI FADT,
400 * PCI bridge quirks, or the "pci=nomsi" kernel command-line option.
401 */
402bool pci_msi_enabled(void)
403{
404 return pci_msi_enable;
405}
406EXPORT_SYMBOL(pci_msi_enabled);
407