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// SPDX-License-Identifier: GPL-2.0
/*
* Intel IXP4xx OF physmap add-on
* Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
*
* Based on the ixp4xx.c map driver, originally written by:
* Intel Corporation
* Deepak Saxena <dsaxena@mvista.com>
* Copyright (C) 2002 Intel Corporation
* Copyright (C) 2003-2004 MontaVista Software, Inc.
*/
#include <linux/export.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/mtd/map.h>
#include <linux/mtd/xip.h>
#include "physmap-ixp4xx.h"
/*
* Read/write a 16 bit word from flash address 'addr'.
*
* When the cpu is in little-endian mode it swizzles the address lines
* ('address coherency') so we need to undo the swizzling to ensure commands
* and the like end up on the correct flash address.
*
* To further complicate matters, due to the way the expansion bus controller
* handles 32 bit reads, the byte stream ABCD is stored on the flash as:
* D15 D0
* +---+---+
* | A | B | 0
* +---+---+
* | C | D | 2
* +---+---+
* This means that on LE systems each 16 bit word must be swapped. Note that
* this requires CONFIG_MTD_CFI_BE_BYTE_SWAP to be enabled to 'unswap' the CFI
* data and other flash commands which are always in D7-D0.
*/
#ifndef CONFIG_CPU_BIG_ENDIAN
static inline u16 flash_read16(void __iomem *addr)
{
return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
}
static inline void flash_write16(u16 d, void __iomem *addr)
{
__raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
}
#define BYTE0(h) ((h) & 0xFF)
#define BYTE1(h) (((h) >> 8) & 0xFF)
#else
static inline u16 flash_read16(const void __iomem *addr)
{
return __raw_readw(addr);
}
static inline void flash_write16(u16 d, void __iomem *addr)
{
__raw_writew(d, addr);
}
#define BYTE0(h) (((h) >> 8) & 0xFF)
#define BYTE1(h) ((h) & 0xFF)
#endif
static map_word ixp4xx_read16(struct map_info *map, unsigned long ofs)
{
map_word val;
val.x[0] = flash_read16(map->virt + ofs);
return val;
}
/*
* The IXP4xx expansion bus only allows 16-bit wide acceses
* when attached to a 16-bit wide device (such as the 28F128J3A),
* so we can't just memcpy_fromio().
*/
static void ixp4xx_copy_from(struct map_info *map, void *to,
unsigned long from, ssize_t len)
{
u8 *dest = (u8 *) to;
void __iomem *src = map->virt + from;
if (len <= 0)
return;
if (from & 1) {
*dest++ = BYTE1(flash_read16(src-1));
src++;
--len;
}
while (len >= 2) {
u16 data = flash_read16(src);
*dest++ = BYTE0(data);
*dest++ = BYTE1(data);
src += 2;
len -= 2;
}
if (len > 0)
*dest++ = BYTE0(flash_read16(src));
}
static void ixp4xx_write16(struct map_info *map, map_word d, unsigned long adr)
{
flash_write16(d.x[0], map->virt + adr);
}
int of_flash_probe_ixp4xx(struct platform_device *pdev,
struct device_node *np,
struct map_info *map)
{
struct device *dev = &pdev->dev;
/* Multiplatform guard */
if (!of_device_is_compatible(np, "intel,ixp4xx-flash"))
return 0;
map->read = ixp4xx_read16;
map->write = ixp4xx_write16;
map->copy_from = ixp4xx_copy_from;
map->copy_to = NULL;
dev_info(dev, "initialized Intel IXP4xx-specific physmap control\n");
return 0;
}
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