1/*
2 * OF helpers for IOMMU
3 *
4 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20#include <linux/export.h>
21#include <linux/iommu.h>
22#include <linux/limits.h>
23#include <linux/of.h>
24#include <linux/of_iommu.h>
25#include <linux/slab.h>
26
27static const struct of_device_id __iommu_of_table_sentinel
28	__used __section(__iommu_of_table_end);
29
30/**
31 * of_get_dma_window - Parse *dma-window property and returns 0 if found.
32 *
33 * @dn: device node
34 * @prefix: prefix for property name if any
35 * @index: index to start to parse
36 * @busno: Returns busno if supported. Otherwise pass NULL
37 * @addr: Returns address that DMA starts
38 * @size: Returns the range that DMA can handle
39 *
40 * This supports different formats flexibly. "prefix" can be
41 * configured if any. "busno" and "index" are optionally
42 * specified. Set 0(or NULL) if not used.
43 */
44int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
45		      unsigned long *busno, dma_addr_t *addr, size_t *size)
46{
47	const __be32 *dma_window, *end;
48	int bytes, cur_index = 0;
49	char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
50
51	if (!dn || !addr || !size)
52		return -EINVAL;
53
54	if (!prefix)
55		prefix = "";
56
57	snprintf(propname, sizeof(propname), "%sdma-window", prefix);
58	snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
59	snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
60
61	dma_window = of_get_property(dn, propname, &bytes);
62	if (!dma_window)
63		return -ENODEV;
64	end = dma_window + bytes / sizeof(*dma_window);
65
66	while (dma_window < end) {
67		u32 cells;
68		const void *prop;
69
70		/* busno is one cell if supported */
71		if (busno)
72			*busno = be32_to_cpup(dma_window++);
73
74		prop = of_get_property(dn, addrname, NULL);
75		if (!prop)
76			prop = of_get_property(dn, "#address-cells", NULL);
77
78		cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
79		if (!cells)
80			return -EINVAL;
81		*addr = of_read_number(dma_window, cells);
82		dma_window += cells;
83
84		prop = of_get_property(dn, sizename, NULL);
85		cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
86		if (!cells)
87			return -EINVAL;
88		*size = of_read_number(dma_window, cells);
89		dma_window += cells;
90
91		if (cur_index++ == index)
92			break;
93	}
94	return 0;
95}
96EXPORT_SYMBOL_GPL(of_get_dma_window);
97
98struct of_iommu_node {
99	struct list_head list;
100	struct device_node *np;
101	struct iommu_ops *ops;
102};
103static LIST_HEAD(of_iommu_list);
104static DEFINE_SPINLOCK(of_iommu_lock);
105
106void of_iommu_set_ops(struct device_node *np, struct iommu_ops *ops)
107{
108	struct of_iommu_node *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
109
110	if (WARN_ON(!iommu))
111		return;
112
113	INIT_LIST_HEAD(&iommu->list);
114	iommu->np = np;
115	iommu->ops = ops;
116	spin_lock(&of_iommu_lock);
117	list_add_tail(&iommu->list, &of_iommu_list);
118	spin_unlock(&of_iommu_lock);
119}
120
121struct iommu_ops *of_iommu_get_ops(struct device_node *np)
122{
123	struct of_iommu_node *node;
124	struct iommu_ops *ops = NULL;
125
126	spin_lock(&of_iommu_lock);
127	list_for_each_entry(node, &of_iommu_list, list)
128		if (node->np == np) {
129			ops = node->ops;
130			break;
131		}
132	spin_unlock(&of_iommu_lock);
133	return ops;
134}
135
136struct iommu_ops *of_iommu_configure(struct device *dev,
137				     struct device_node *master_np)
138{
139	struct of_phandle_args iommu_spec;
140	struct device_node *np;
141	struct iommu_ops *ops = NULL;
142	int idx = 0;
143
144	if (dev_is_pci(dev)) {
145		dev_err(dev, "IOMMU is currently not supported for PCI\n");
146		return NULL;
147	}
148
149	/*
150	 * We don't currently walk up the tree looking for a parent IOMMU.
151	 * See the `Notes:' section of
152	 * Documentation/devicetree/bindings/iommu/iommu.txt
153	 */
154	while (!of_parse_phandle_with_args(master_np, "iommus",
155					   "#iommu-cells", idx,
156					   &iommu_spec)) {
157		np = iommu_spec.np;
158		ops = of_iommu_get_ops(np);
159
160		if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
161			goto err_put_node;
162
163		of_node_put(np);
164		idx++;
165	}
166
167	return ops;
168
169err_put_node:
170	of_node_put(np);
171	return NULL;
172}
173
174void __init of_iommu_init(void)
175{
176	struct device_node *np;
177	const struct of_device_id *match, *matches = &__iommu_of_table;
178
179	for_each_matching_node_and_match(np, matches, &match) {
180		const of_iommu_init_fn init_fn = match->data;
181
182		if (init_fn(np))
183			pr_err("Failed to initialise IOMMU %s\n",
184				of_node_full_name(np));
185	}
186}
187