1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC 4 * 5 * Authors: 6 * Serge Semin <Sergey.Semin@baikalelectronics.ru> 7 * 8 * Baikal-T1 Physically Mapped Internal ROM driver 9 */ 10 #include <linux/bits.h> 11 #include <linux/device.h> 12 #include <linux/kernel.h> 13 #include <linux/mtd/map.h> 14 #include <linux/mtd/xip.h> 15 #include <linux/mux/consumer.h> 16 #include <linux/of.h> 17 #include <linux/platform_device.h> 18 #include <linux/string.h> 19 #include <linux/types.h> 20 21 #include "physmap-bt1-rom.h" 22 23 /* 24 * Baikal-T1 SoC ROMs are only accessible by the dword-aligned instructions. 25 * We have to take this into account when implementing the data read-methods. 26 * Note there is no need in bothering with endianness, since both Baikal-T1 27 * CPU and MMIO are LE. 28 */ 29 static map_word __xipram bt1_rom_map_read(struct map_info *map, 30 unsigned long ofs) 31 { 32 void __iomem *src = map->virt + ofs; 33 unsigned int shift; 34 map_word ret; 35 u32 data; 36 37 /* Read data within offset dword. */ 38 shift = (uintptr_t)src & 0x3; 39 data = readl_relaxed(src - shift); 40 if (!shift) { 41 ret.x[0] = data; 42 return ret; 43 } 44 ret.x[0] = data >> (shift * BITS_PER_BYTE); 45 46 /* Read data from the next dword. */ 47 shift = 4 - shift; 48 if (ofs + shift >= map->size) 49 return ret; 50 51 data = readl_relaxed(src + shift); 52 ret.x[0] |= data << (shift * BITS_PER_BYTE); 53 54 return ret; 55 } 56 57 static void __xipram bt1_rom_map_copy_from(struct map_info *map, 58 void *to, unsigned long from, 59 ssize_t len) 60 { 61 void __iomem *src = map->virt + from; 62 unsigned int shift, chunk; 63 u32 data; 64 65 if (len <= 0 || from >= map->size) 66 return; 67 68 /* Make sure we don't go over the map limit. */ 69 len = min_t(ssize_t, map->size - from, len); 70 71 /* 72 * Since requested data size can be pretty big we have to implement 73 * the copy procedure as optimal as possible. That's why it's split 74 * up into the next three stages: unaligned head, aligned body, 75 * unaligned tail. 76 */ 77 shift = (uintptr_t)src & 0x3; 78 if (shift) { 79 chunk = min_t(ssize_t, 4 - shift, len); 80 data = readl_relaxed(src - shift); 81 memcpy(to, (char *)&data + shift, chunk); 82 src += chunk; 83 to += chunk; 84 len -= chunk; 85 } 86 87 while (len >= 4) { 88 data = readl_relaxed(src); 89 memcpy(to, &data, 4); 90 src += 4; 91 to += 4; 92 len -= 4; 93 } 94 95 if (len) { 96 data = readl_relaxed(src); 97 memcpy(to, &data, len); 98 } 99 } 100 101 int of_flash_probe_bt1_rom(struct platform_device *pdev, 102 struct device_node *np, 103 struct map_info *map) 104 { 105 struct device *dev = &pdev->dev; 106 107 /* It's supposed to be read-only MTD. */ 108 if (!of_device_is_compatible(np, "mtd-rom")) { 109 dev_info(dev, "No mtd-rom compatible string\n"); 110 return 0; 111 } 112 113 /* Multiplatform guard. */ 114 if (!of_device_is_compatible(np, "baikal,bt1-int-rom")) 115 return 0; 116 117 /* Sanity check the device parameters retrieved from DTB. */ 118 if (map->bankwidth != 4) 119 dev_warn(dev, "Bank width is supposed to be 32 bits wide\n"); 120 121 map->read = bt1_rom_map_read; 122 map->copy_from = bt1_rom_map_copy_from; 123 124 return 0; 125 } 126