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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC4 *5 * Authors:6 * Serge Semin <Sergey.Semin@baikalelectronics.ru>7 *8 * Baikal-T1 Physically Mapped Internal ROM driver9 */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-T127 * CPU and MMIO are LE.28 */29static 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 57static 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 implement73 * the copy procedure as optimal as possible. That's why it's split74 * 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 101int 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