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(d);
17	irq_chip_mask_parent(d);
18}
19
20static void its_unmask_msi_irq(struct irq_data *d)
21{
22	pci_msi_unmask_irq(d);
23	irq_chip_unmask_parent(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->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, its_get_pci_alias, &alias_dev);
73	if (alias_dev != pdev) {
74		if (alias_dev->subordinate)
75			pci_walk_bus(alias_dev->subordinate,
76				     its_pci_msi_vec_count, &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(handle, DOMAIN_BUS_NEXUS);
119	if (!parent || !msi_get_domain_info(parent)) {
120		pr_err("%s: Unable to locate ITS domain\n", name);
121		return -ENXIO;
122	}
123
124	if (!pci_msi_create_irq_domain(handle, &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, its_device_id); np;
138	     np = of_find_matching_node(np, its_device_id)) {
139		if (!of_device_is_available(np))
140			continue;
141		if (!of_property_read_bool(np, "msi-controller"))
142			continue;
143
144		if (its_pci_msi_init_one(of_node_to_fwnode(np), 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, "ITS@0x%lx",
166			      (long)its_entry->base_address);
167	dom_handle = iort_find_domain_token(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(dom_handle, node_name);
174	if (!err)
175		pr_info("PCI/MSI: %s domain created\n", node_name);
176
177out:
178	kfree(node_name);
179	return err;
180}
181
182static int __init its_pci_acpi_msi_init(void)
183{
184	acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
185			      its_pci_msi_parse_madt, 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