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 
14 static void its_mask_msi_irq(struct irq_data *d)
15 {
16 	pci_msi_mask_irq(d);
17 	irq_chip_mask_parent(d);
18 }
19 
20 static void its_unmask_msi_irq(struct irq_data *d)
21 {
22 	pci_msi_unmask_irq(d);
23 	irq_chip_unmask_parent(d);
24 }
25 
26 static 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 	.irq_write_msi_msg	= pci_msi_domain_write_msg,
32 };
33 
34 static int its_pci_msi_vec_count(struct pci_dev *pdev, void *data)
35 {
36 	int msi, msix, *count = data;
37 
38 	msi = max(pci_msi_vec_count(pdev), 0);
39 	msix = max(pci_msix_vec_count(pdev), 0);
40 	*count += max(msi, msix);
41 
42 	return 0;
43 }
44 
45 static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
46 {
47 	struct pci_dev **alias_dev = data;
48 
49 	*alias_dev = pdev;
50 
51 	return 0;
52 }
53 
54 static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
55 			       int nvec, msi_alloc_info_t *info)
56 {
57 	struct pci_dev *pdev, *alias_dev;
58 	struct msi_domain_info *msi_info;
59 	int alias_count = 0, minnvec = 1;
60 
61 	if (!dev_is_pci(dev))
62 		return -EINVAL;
63 
64 	msi_info = msi_get_domain_info(domain->parent);
65 
66 	pdev = to_pci_dev(dev);
67 	/*
68 	 * If pdev is downstream of any aliasing bridges, take an upper
69 	 * bound of how many other vectors could map to the same DevID.
70 	 * Also tell the ITS that the signalling will come from a proxy
71 	 * device, and that special allocation rules apply.
72 	 */
73 	pci_for_each_dma_alias(pdev, its_get_pci_alias, &alias_dev);
74 	if (alias_dev != pdev) {
75 		if (alias_dev->subordinate)
76 			pci_walk_bus(alias_dev->subordinate,
77 				     its_pci_msi_vec_count, &alias_count);
78 		info->flags |= MSI_ALLOC_FLAGS_PROXY_DEVICE;
79 	}
80 
81 	/* ITS specific DeviceID, as the core ITS ignores dev. */
82 	info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev);
83 
84 	/*
85 	 * Always allocate a power of 2, and special case device 0 for
86 	 * broken systems where the DevID is not wired (and all devices
87 	 * appear as DevID 0). For that reason, we generously allocate a
88 	 * minimum of 32 MSIs for DevID 0. If you want more because all
89 	 * your devices are aliasing to DevID 0, consider fixing your HW.
90 	 */
91 	nvec = max(nvec, alias_count);
92 	if (!info->scratchpad[0].ul)
93 		minnvec = 32;
94 	nvec = max_t(int, minnvec, roundup_pow_of_two(nvec));
95 	return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info);
96 }
97 
98 static struct msi_domain_ops its_pci_msi_ops = {
99 	.msi_prepare	= its_pci_msi_prepare,
100 };
101 
102 static struct msi_domain_info its_pci_msi_domain_info = {
103 	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
104 		   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
105 	.ops	= &its_pci_msi_ops,
106 	.chip	= &its_msi_irq_chip,
107 };
108 
109 static struct of_device_id its_device_id[] = {
110 	{	.compatible	= "arm,gic-v3-its",	},
111 	{},
112 };
113 
114 static int __init its_pci_msi_init_one(struct fwnode_handle *handle,
115 				       const char *name)
116 {
117 	struct irq_domain *parent;
118 
119 	parent = irq_find_matching_fwnode(handle, DOMAIN_BUS_NEXUS);
120 	if (!parent || !msi_get_domain_info(parent)) {
121 		pr_err("%s: Unable to locate ITS domain\n", name);
122 		return -ENXIO;
123 	}
124 
125 	if (!pci_msi_create_irq_domain(handle, &its_pci_msi_domain_info,
126 				       parent)) {
127 		pr_err("%s: Unable to create PCI domain\n", name);
128 		return -ENOMEM;
129 	}
130 
131 	return 0;
132 }
133 
134 static int __init its_pci_of_msi_init(void)
135 {
136 	struct device_node *np;
137 
138 	for (np = of_find_matching_node(NULL, its_device_id); np;
139 	     np = of_find_matching_node(np, its_device_id)) {
140 		if (!of_device_is_available(np))
141 			continue;
142 		if (!of_property_read_bool(np, "msi-controller"))
143 			continue;
144 
145 		if (its_pci_msi_init_one(of_node_to_fwnode(np), np->full_name))
146 			continue;
147 
148 		pr_info("PCI/MSI: %pOF domain created\n", np);
149 	}
150 
151 	return 0;
152 }
153 
154 #ifdef CONFIG_ACPI
155 
156 static int __init
157 its_pci_msi_parse_madt(union acpi_subtable_headers *header,
158 		       const unsigned long end)
159 {
160 	struct acpi_madt_generic_translator *its_entry;
161 	struct fwnode_handle *dom_handle;
162 	const char *node_name;
163 	int err = -ENXIO;
164 
165 	its_entry = (struct acpi_madt_generic_translator *)header;
166 	node_name = kasprintf(GFP_KERNEL, "ITS@0x%lx",
167 			      (long)its_entry->base_address);
168 	dom_handle = iort_find_domain_token(its_entry->translation_id);
169 	if (!dom_handle) {
170 		pr_err("%s: Unable to locate ITS domain handle\n", node_name);
171 		goto out;
172 	}
173 
174 	err = its_pci_msi_init_one(dom_handle, node_name);
175 	if (!err)
176 		pr_info("PCI/MSI: %s domain created\n", node_name);
177 
178 out:
179 	kfree(node_name);
180 	return err;
181 }
182 
183 static int __init its_pci_acpi_msi_init(void)
184 {
185 	acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
186 			      its_pci_msi_parse_madt, 0);
187 	return 0;
188 }
189 #else
190 static int __init its_pci_acpi_msi_init(void)
191 {
192 	return 0;
193 }
194 #endif
195 
196 static int __init its_pci_msi_init(void)
197 {
198 	its_pci_of_msi_init();
199 	its_pci_acpi_msi_init();
200 
201 	return 0;
202 }
203 early_initcall(its_pci_msi_init);
204