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126 lines
3.0 KiB
126 lines
3.0 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) 2020 BAIKAL ELECTRONICS, JSC |
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* |
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* Authors: |
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* Serge Semin <[email protected]> |
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* |
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* Baikal-T1 Physically Mapped Internal ROM driver |
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*/ |
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#include <linux/bits.h> |
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#include <linux/device.h> |
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#include <linux/kernel.h> |
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#include <linux/mtd/map.h> |
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#include <linux/mtd/xip.h> |
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#include <linux/mux/consumer.h> |
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#include <linux/of.h> |
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#include <linux/of_device.h> |
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#include <linux/platform_device.h> |
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#include <linux/string.h> |
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#include <linux/types.h> |
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#include "physmap-bt1-rom.h" |
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/* |
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* Baikal-T1 SoC ROMs are only accessible by the dword-aligned instructions. |
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* We have to take this into account when implementing the data read-methods. |
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* Note there is no need in bothering with endianness, since both Baikal-T1 |
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* CPU and MMIO are LE. |
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*/ |
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static map_word __xipram bt1_rom_map_read(struct map_info *map, |
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unsigned long ofs) |
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{ |
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void __iomem *src = map->virt + ofs; |
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unsigned int shift; |
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map_word ret; |
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u32 data; |
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/* Read data within offset dword. */ |
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shift = (uintptr_t)src & 0x3; |
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data = readl_relaxed(src - shift); |
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if (!shift) { |
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ret.x[0] = data; |
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return ret; |
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} |
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ret.x[0] = data >> (shift * BITS_PER_BYTE); |
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/* Read data from the next dword. */ |
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shift = 4 - shift; |
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if (ofs + shift >= map->size) |
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return ret; |
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data = readl_relaxed(src + shift); |
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ret.x[0] |= data << (shift * BITS_PER_BYTE); |
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return ret; |
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} |
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static void __xipram bt1_rom_map_copy_from(struct map_info *map, |
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void *to, unsigned long from, |
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ssize_t len) |
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{ |
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void __iomem *src = map->virt + from; |
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unsigned int shift, chunk; |
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u32 data; |
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if (len <= 0 || from >= map->size) |
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return; |
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/* Make sure we don't go over the map limit. */ |
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len = min_t(ssize_t, map->size - from, len); |
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/* |
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* Since requested data size can be pretty big we have to implement |
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* the copy procedure as optimal as possible. That's why it's split |
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* up into the next three stages: unaligned head, aligned body, |
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* unaligned tail. |
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*/ |
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shift = (uintptr_t)src & 0x3; |
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if (shift) { |
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chunk = min_t(ssize_t, 4 - shift, len); |
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data = readl_relaxed(src - shift); |
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memcpy(to, (char *)&data + shift, chunk); |
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src += chunk; |
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to += chunk; |
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len -= chunk; |
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} |
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while (len >= 4) { |
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data = readl_relaxed(src); |
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memcpy(to, &data, 4); |
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src += 4; |
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to += 4; |
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len -= 4; |
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} |
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if (len) { |
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data = readl_relaxed(src); |
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memcpy(to, &data, len); |
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} |
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} |
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int of_flash_probe_bt1_rom(struct platform_device *pdev, |
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struct device_node *np, |
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struct map_info *map) |
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{ |
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struct device *dev = &pdev->dev; |
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/* It's supposed to be read-only MTD. */ |
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if (!of_device_is_compatible(np, "mtd-rom")) { |
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dev_info(dev, "No mtd-rom compatible string\n"); |
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return 0; |
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} |
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/* Multiplatform guard. */ |
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if (!of_device_is_compatible(np, "baikal,bt1-int-rom")) |
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return 0; |
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/* Sanity check the device parameters retrieved from DTB. */ |
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if (map->bankwidth != 4) |
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dev_warn(dev, "Bank width is supposed to be 32 bits wide\n"); |
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map->read = bt1_rom_map_read; |
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map->copy_from = bt1_rom_map_copy_from; |
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return 0; |
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}
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