1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2013-2015 ARM Limited, All Rights Reserved.
4 * Author: Marc Zyngier <marc.zyngier@arm.com>
5 */
6
7#include <linux/acpi_iort.h>
8#include <linux/pci.h>
9#include <linux/msi.h>
10#include <linux/of.h>
11#include <linux/of_irq.h>
12#include <linux/of_pci.h>
13
14static void its_mask_msi_irq(struct irq_data *d)
15{
16 pci_msi_mask_irq(data: d);
17 irq_chip_mask_parent(data: d);
18}
19
20static void its_unmask_msi_irq(struct irq_data *d)
21{
22 pci_msi_unmask_irq(data: d);
23 irq_chip_unmask_parent(data: d);
24}
25
26static struct irq_chip its_msi_irq_chip = {
27 .name = "ITS-MSI",
28 .irq_unmask = its_unmask_msi_irq,
29 .irq_mask = its_mask_msi_irq,
30 .irq_eoi = irq_chip_eoi_parent,
31};
32
33static int its_pci_msi_vec_count(struct pci_dev *pdev, void *data)
34{
35 int msi, msix, *count = data;
36
37 msi = max(pci_msi_vec_count(pdev), 0);
38 msix = max(pci_msix_vec_count(pdev), 0);
39 *count += max(msi, msix);
40
41 return 0;
42}
43
44static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
45{
46 struct pci_dev **alias_dev = data;
47
48 *alias_dev = pdev;
49
50 return 0;
51}
52
53static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
54 int nvec, msi_alloc_info_t *info)
55{
56 struct pci_dev *pdev, *alias_dev;
57 struct msi_domain_info *msi_info;
58 int alias_count = 0, minnvec = 1;
59
60 if (!dev_is_pci(dev))
61 return -EINVAL;
62
63 msi_info = msi_get_domain_info(domain: domain->parent);
64
65 pdev = to_pci_dev(dev);
66 /*
67 * If pdev is downstream of any aliasing bridges, take an upper
68 * bound of how many other vectors could map to the same DevID.
69 * Also tell the ITS that the signalling will come from a proxy
70 * device, and that special allocation rules apply.
71 */
72 pci_for_each_dma_alias(pdev, fn: its_get_pci_alias, data: &alias_dev);
73 if (alias_dev != pdev) {
74 if (alias_dev->subordinate)
75 pci_walk_bus(top: alias_dev->subordinate,
76 cb: its_pci_msi_vec_count, userdata: &alias_count);
77 info->flags |= MSI_ALLOC_FLAGS_PROXY_DEVICE;
78 }
79
80 /* ITS specific DeviceID, as the core ITS ignores dev. */
81 info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev);
82
83 /*
84 * Always allocate a power of 2, and special case device 0 for
85 * broken systems where the DevID is not wired (and all devices
86 * appear as DevID 0). For that reason, we generously allocate a
87 * minimum of 32 MSIs for DevID 0. If you want more because all
88 * your devices are aliasing to DevID 0, consider fixing your HW.
89 */
90 nvec = max(nvec, alias_count);
91 if (!info->scratchpad[0].ul)
92 minnvec = 32;
93 nvec = max_t(int, minnvec, roundup_pow_of_two(nvec));
94 return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info);
95}
96
97static struct msi_domain_ops its_pci_msi_ops = {
98 .msi_prepare = its_pci_msi_prepare,
99};
100
101static struct msi_domain_info its_pci_msi_domain_info = {
102 .flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
103 MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
104 .ops = &its_pci_msi_ops,
105 .chip = &its_msi_irq_chip,
106};
107
108static struct of_device_id its_device_id[] = {
109 { .compatible = "arm,gic-v3-its", },
110 {},
111};
112
113static int __init its_pci_msi_init_one(struct fwnode_handle *handle,
114 const char *name)
115{
116 struct irq_domain *parent;
117
118 parent = irq_find_matching_fwnode(fwnode: handle, bus_token: DOMAIN_BUS_NEXUS);
119 if (!parent || !msi_get_domain_info(domain: parent)) {
120 pr_err("%s: Unable to locate ITS domain\n", name);
121 return -ENXIO;
122 }
123
124 if (!pci_msi_create_irq_domain(fwnode: handle, info: &its_pci_msi_domain_info,
125 parent)) {
126 pr_err("%s: Unable to create PCI domain\n", name);
127 return -ENOMEM;
128 }
129
130 return 0;
131}
132
133static int __init its_pci_of_msi_init(void)
134{
135 struct device_node *np;
136
137 for (np = of_find_matching_node(NULL, matches: its_device_id); np;
138 np = of_find_matching_node(from: np, matches: its_device_id)) {
139 if (!of_device_is_available(device: np))
140 continue;
141 if (!of_property_read_bool(np, propname: "msi-controller"))
142 continue;
143
144 if (its_pci_msi_init_one(handle: of_node_to_fwnode(node: np), name: np->full_name))
145 continue;
146
147 pr_info("PCI/MSI: %pOF domain created\n", np);
148 }
149
150 return 0;
151}
152
153#ifdef CONFIG_ACPI
154
155static int __init
156its_pci_msi_parse_madt(union acpi_subtable_headers *header,
157 const unsigned long end)
158{
159 struct acpi_madt_generic_translator *its_entry;
160 struct fwnode_handle *dom_handle;
161 const char *node_name;
162 int err = -ENXIO;
163
164 its_entry = (struct acpi_madt_generic_translator *)header;
165 node_name = kasprintf(GFP_KERNEL, fmt: "ITS@0x%lx",
166 (long)its_entry->base_address);
167 dom_handle = iort_find_domain_token(trans_id: its_entry->translation_id);
168 if (!dom_handle) {
169 pr_err("%s: Unable to locate ITS domain handle\n", node_name);
170 goto out;
171 }
172
173 err = its_pci_msi_init_one(handle: dom_handle, name: node_name);
174 if (!err)
175 pr_info("PCI/MSI: %s domain created\n", node_name);
176
177out:
178 kfree(objp: node_name);
179 return err;
180}
181
182static int __init its_pci_acpi_msi_init(void)
183{
184 acpi_table_parse_madt(id: ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
185 handler: its_pci_msi_parse_madt, max_entries: 0);
186 return 0;
187}
188#else
189static int __init its_pci_acpi_msi_init(void)
190{
191 return 0;
192}
193#endif
194
195static int __init its_pci_msi_init(void)
196{
197 its_pci_of_msi_init();
198 its_pci_acpi_msi_init();
199
200 return 0;
201}
202early_initcall(its_pci_msi_init);
203

source code of linux/drivers/irqchip/irq-gic-v3-its-pci-msi.c