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/limits.h>
22#include <linux/of.h>
23#include <linux/of_iommu.h>
24
25/**
26 * of_get_dma_window - Parse *dma-window property and returns 0 if found.
27 *
28 * @dn: device node
29 * @prefix: prefix for property name if any
30 * @index: index to start to parse
31 * @busno: Returns busno if supported. Otherwise pass NULL
32 * @addr: Returns address that DMA starts
33 * @size: Returns the range that DMA can handle
34 *
35 * This supports different formats flexibly. "prefix" can be
36 * configured if any. "busno" and "index" are optionally
37 * specified. Set 0(or NULL) if not used.
38 */
39int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
40		      unsigned long *busno, dma_addr_t *addr, size_t *size)
41{
42	const __be32 *dma_window, *end;
43	int bytes, cur_index = 0;
44	char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
45
46	if (!dn || !addr || !size)
47		return -EINVAL;
48
49	if (!prefix)
50		prefix = "";
51
52	snprintf(propname, sizeof(propname), "%sdma-window", prefix);
53	snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
54	snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
55
56	dma_window = of_get_property(dn, propname, &bytes);
57	if (!dma_window)
58		return -ENODEV;
59	end = dma_window + bytes / sizeof(*dma_window);
60
61	while (dma_window < end) {
62		u32 cells;
63		const void *prop;
64
65		/* busno is one cell if supported */
66		if (busno)
67			*busno = be32_to_cpup(dma_window++);
68
69		prop = of_get_property(dn, addrname, NULL);
70		if (!prop)
71			prop = of_get_property(dn, "#address-cells", NULL);
72
73		cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
74		if (!cells)
75			return -EINVAL;
76		*addr = of_read_number(dma_window, cells);
77		dma_window += cells;
78
79		prop = of_get_property(dn, sizename, NULL);
80		cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
81		if (!cells)
82			return -EINVAL;
83		*size = of_read_number(dma_window, cells);
84		dma_window += cells;
85
86		if (cur_index++ == index)
87			break;
88	}
89	return 0;
90}
91EXPORT_SYMBOL_GPL(of_get_dma_window);