drivers/iommu/of_iommu.c

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