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 #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  */
  39 int 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 }
  91 EXPORT_SYMBOL_GPL(of_get_dma_window);