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>

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);