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); 92