1// SPDX-License-Identifier: GPL-2.0-only
2// Copyright (C) 2022 Linutronix GmbH
3// Copyright (C) 2022 Intel
4
5#include <linux/export.h>
6
7#include <linux/irqchip/irq-msi-lib.h>
8
9/**
10 * msi_lib_init_dev_msi_info - Domain info setup for MSI domains
11 * @dev: The device for which the domain is created for
12 * @domain: The domain providing this callback
13 * @real_parent: The real parent domain of the domain to be initialized
14 * which might be a domain built on top of @domain or
15 * @domain itself
16 * @info: The domain info for the domain to be initialize
17 *
18 * This function is to be used for all types of MSI domains above the root
19 * parent domain and any intermediates. The topmost parent domain specific
20 * functionality is determined via @real_parent.
21 *
22 * All intermediate domains between the root and the device domain must
23 * have either msi_parent_ops.init_dev_msi_info = msi_parent_init_dev_msi_info
24 * or invoke it down the line.
25 */
26bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
27 struct irq_domain *real_parent,
28 struct msi_domain_info *info)
29{
30 const struct msi_parent_ops *pops = real_parent->msi_parent_ops;
31 struct irq_chip *chip = info->chip;
32 u32 required_flags;
33
34 /* Parent ops available? */
35 if (WARN_ON_ONCE(!pops))
36 return false;
37
38 /*
39 * MSI parent domain specific settings. For now there is only the
40 * root parent domain, e.g. NEXUS, acting as a MSI parent, but it is
41 * possible to stack MSI parents. See x86 vector -> irq remapping
42 */
43 if (domain->bus_token == pops->bus_select_token) {
44 if (WARN_ON_ONCE(domain != real_parent))
45 return false;
46 } else {
47 WARN_ON_ONCE(1);
48 return false;
49 }
50
51 required_flags = pops->required_flags;
52
53 /* Is the target domain bus token supported? */
54 switch(info->bus_token) {
55 case DOMAIN_BUS_PCI_DEVICE_MSI:
56 case DOMAIN_BUS_PCI_DEVICE_MSIX:
57 if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PCI_MSI)))
58 return false;
59
60 break;
61 case DOMAIN_BUS_DEVICE_MSI:
62 /*
63 * Per device MSI should never have any MSI feature bits
64 * set. It's sole purpose is to create a dumb interrupt
65 * chip which has a device specific irq_write_msi_msg()
66 * callback.
67 */
68 if (WARN_ON_ONCE(info->flags))
69 return false;
70
71 /* Core managed MSI descriptors */
72 info->flags = MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS | MSI_FLAG_FREE_MSI_DESCS;
73 fallthrough;
74 case DOMAIN_BUS_WIRED_TO_MSI:
75 /* Remove PCI specific flags */
76 required_flags &= ~MSI_FLAG_PCI_MSI_MASK_PARENT;
77 break;
78 default:
79 /*
80 * This should never be reached. See
81 * msi_lib_irq_domain_select()
82 */
83 WARN_ON_ONCE(1);
84 return false;
85 }
86
87 /*
88 * Mask out the domain specific MSI feature flags which are not
89 * supported by the real parent.
90 */
91 info->flags &= pops->supported_flags;
92 /* Enforce the required flags */
93 info->flags |= required_flags;
94
95 /* Chip updates for all child bus types */
96 if (!chip->irq_eoi && (pops->chip_flags & MSI_CHIP_FLAG_SET_EOI))
97 chip->irq_eoi = irq_chip_eoi_parent;
98 if (!chip->irq_ack && (pops->chip_flags & MSI_CHIP_FLAG_SET_ACK))
99 chip->irq_ack = irq_chip_ack_parent;
100
101 /*
102 * The device MSI domain can never have a set affinity callback. It
103 * always has to rely on the parent domain to handle affinity
104 * settings. The device MSI domain just has to write the resulting
105 * MSI message into the hardware which is the whole purpose of the
106 * device MSI domain aside of mask/unmask which is provided e.g. by
107 * PCI/MSI device domains.
108 *
109 * The exception to the rule is when the underlying domain
110 * tells you that affinity is not a thing -- for example when
111 * everything is muxed behind a single interrupt.
112 */
113 if (!chip->irq_set_affinity && !(info->flags & MSI_FLAG_NO_AFFINITY))
114 chip->irq_set_affinity = msi_domain_set_affinity;
115
116 /*
117 * If the parent domain insists on being in charge of masking, obey
118 * blindly. The interrupt is un-masked at the PCI level on startup
119 * and masked on shutdown to prevent rogue interrupts after the
120 * driver freed the interrupt. Not masking it at the PCI level
121 * speeds up operation for disable/enable_irq() as it avoids
122 * getting all the way out to the PCI device.
123 */
124 if (info->flags & MSI_FLAG_PCI_MSI_MASK_PARENT) {
125 chip->irq_mask = irq_chip_mask_parent;
126 chip->irq_unmask = irq_chip_unmask_parent;
127 }
128
129 return true;
130}
131EXPORT_SYMBOL_GPL(msi_lib_init_dev_msi_info);
132
133/**
134 * msi_lib_irq_domain_select - Shared select function for NEXUS domains
135 * @d: Pointer to the irq domain on which select is invoked
136 * @fwspec: Firmware spec describing what is searched
137 * @bus_token: The bus token for which a matching irq domain is looked up
138 *
139 * Returns: %0 if @d is not what is being looked for
140 *
141 * %1 if @d is either the domain which is directly searched for or
142 * if @d is providing the parent MSI domain for the functionality
143 * requested with @bus_token.
144 */
145int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
146 enum irq_domain_bus_token bus_token)
147{
148 const struct msi_parent_ops *ops = d->msi_parent_ops;
149 u32 busmask = BIT(bus_token);
150
151 if (!ops)
152 return 0;
153
154 struct fwnode_handle *fwh __free(fwnode_handle) =
155 d->flags & IRQ_DOMAIN_FLAG_FWNODE_PARENT ? fwnode_get_parent(fwnode: fwspec->fwnode)
156 : fwnode_handle_get(fwnode: fwspec->fwnode);
157 if (fwh != d->fwnode || fwspec->param_count != 0)
158 return 0;
159
160 /* Handle pure domain searches */
161 if (bus_token == ops->bus_select_token)
162 return 1;
163
164 return !!(ops->bus_select_mask & busmask);
165}
166EXPORT_SYMBOL_GPL(msi_lib_irq_domain_select);
167

source code of linux/drivers/irqchip/irq-msi-lib.c