127 lines
3.0 KiB
C
127 lines
3.0 KiB
C
// 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 <Sergey.Semin@baikalelectronics.ru>
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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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