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