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); 91