LXR linux/drivers/mtd/maps/physmap-ixp4xx.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Intel IXP4xx OF physmap add-on
   4 * Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
   5 *
   6 * Based on the ixp4xx.c map driver, originally written by:
   7 * Intel Corporation
   8 * Deepak Saxena <dsaxena@mvista.com>
   9 * Copyright (C) 2002 Intel Corporation
  10 * Copyright (C) 2003-2004 MontaVista Software, Inc.
  11 */
  12#include <linux/export.h>
  13#include <linux/of.h>
  14#include <linux/of_device.h>
  15#include <linux/mtd/map.h>
  16#include <linux/mtd/xip.h>
  17#include "physmap-ixp4xx.h"
  18
  19/*
  20 * Read/write a 16 bit word from flash address 'addr'.
  21 *
  22 * When the cpu is in little-endian mode it swizzles the address lines
  23 * ('address coherency') so we need to undo the swizzling to ensure commands
  24 * and the like end up on the correct flash address.
  25 *
  26 * To further complicate matters, due to the way the expansion bus controller
  27 * handles 32 bit reads, the byte stream ABCD is stored on the flash as:
  28 *     D15    D0
  29 *     +---+---+
  30 *     | A | B | 0
  31 *     +---+---+
  32 *     | C | D | 2
  33 *     +---+---+
  34 * This means that on LE systems each 16 bit word must be swapped. Note that
  35 * this requires CONFIG_MTD_CFI_BE_BYTE_SWAP to be enabled to 'unswap' the CFI
  36 * data and other flash commands which are always in D7-D0.
  37 */
  38#ifndef CONFIG_CPU_BIG_ENDIAN
  39
  40static inline u16 flash_read16(void __iomem *addr)
  41{
  42        return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
  43}
  44
  45static inline void flash_write16(u16 d, void __iomem *addr)
  46{
  47        __raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
  48}
  49
  50#define BYTE0(h)        ((h) & 0xFF)
  51#define BYTE1(h)        (((h) >> 8) & 0xFF)
  52
  53#else
  54
  55static inline u16 flash_read16(const void __iomem *addr)
  56{
  57        return __raw_readw(addr);
  58}
  59
  60static inline void flash_write16(u16 d, void __iomem *addr)
  61{
  62        __raw_writew(d, addr);
  63}
  64
  65#define BYTE0(h)        (((h) >> 8) & 0xFF)
  66#define BYTE1(h)        ((h) & 0xFF)
  67#endif
  68
  69static map_word ixp4xx_read16(struct map_info *map, unsigned long ofs)
  70{
  71        map_word val;
  72
  73        val.x[0] = flash_read16(map->virt + ofs);
  74        return val;
  75}
  76
  77/*
  78 * The IXP4xx expansion bus only allows 16-bit wide acceses
  79 * when attached to a 16-bit wide device (such as the 28F128J3A),
  80 * so we can't just memcpy_fromio().
  81 */
  82static void ixp4xx_copy_from(struct map_info *map, void *to,
  83                             unsigned long from, ssize_t len)
  84{
  85        u8 *dest = (u8 *) to;
  86        void __iomem *src = map->virt + from;
  87
  88        if (len <= 0)
  89                return;
  90
  91        if (from & 1) {
  92                *dest++ = BYTE1(flash_read16(src-1));
  93                src++;
  94                --len;
  95        }
  96
  97        while (len >= 2) {
  98                u16 data = flash_read16(src);
  99                *dest++ = BYTE0(data);
 100                *dest++ = BYTE1(data);
 101                src += 2;
 102                len -= 2;
 103        }
 104
 105        if (len > 0)
 106                *dest++ = BYTE0(flash_read16(src));
 107}
 108
 109static void ixp4xx_write16(struct map_info *map, map_word d, unsigned long adr)
 110{
 111        flash_write16(d.x[0], map->virt + adr);
 112}
 113
 114int of_flash_probe_ixp4xx(struct platform_device *pdev,
 115                          struct device_node *np,
 116                          struct map_info *map)
 117{
 118        struct device *dev = &pdev->dev;
 119
 120        /* Multiplatform guard */
 121        if (!of_device_is_compatible(np, "intel,ixp4xx-flash"))
 122                return 0;
 123
 124        map->read = ixp4xx_read16;
 125        map->write = ixp4xx_write16;
 126        map->copy_from = ixp4xx_copy_from;
 127        map->copy_to = NULL;
 128
 129        dev_info(dev, "initialized Intel IXP4xx-specific physmap control\n");
 130
 131        return 0;
 132}
 133