of_iommu.c
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/*
* OF helpers for IOMMU
*
* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <linux/export.h>
#include <linux/limits.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
/**
* of_get_dma_window - Parse *dma-window property and returns 0 if found.
*
* @dn: device node
* @prefix: prefix for property name if any
* @index: index to start to parse
* @busno: Returns busno if supported. Otherwise pass NULL
* @addr: Returns address that DMA starts
* @size: Returns the range that DMA can handle
*
* This supports different formats flexibly. "prefix" can be
* configured if any. "busno" and "index" are optionally
* specified. Set 0(or NULL) if not used.
*/
int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
unsigned long *busno, dma_addr_t *addr, size_t *size)
{
const __be32 *dma_window, *end;
int bytes, cur_index = 0;
char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
if (!dn || !addr || !size)
return -EINVAL;
if (!prefix)
prefix = "";
snprintf(propname, sizeof(propname), "%sdma-window", prefix);
snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
dma_window = of_get_property(dn, propname, &bytes);
if (!dma_window)
return -ENODEV;
end = dma_window + bytes / sizeof(*dma_window);
while (dma_window < end) {
u32 cells;
const void *prop;
/* busno is one cell if supported */
if (busno)
*busno = be32_to_cpup(dma_window++);
prop = of_get_property(dn, addrname, NULL);
if (!prop)
prop = of_get_property(dn, "#address-cells", NULL);
cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
if (!cells)
return -EINVAL;
*addr = of_read_number(dma_window, cells);
dma_window += cells;
prop = of_get_property(dn, sizename, NULL);
cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
if (!cells)
return -EINVAL;
*size = of_read_number(dma_window, cells);
dma_window += cells;
if (cur_index++ == index)
break;
}
return 0;
}
EXPORT_SYMBOL_GPL(of_get_dma_window);