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
flash_read16(void __iomem * addr)40 static inline u16 flash_read16(void __iomem *addr)
41 {
42 return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
43 }
44
flash_write16(u16 d,void __iomem * addr)45 static 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
flash_read16(const void __iomem * addr)55 static inline u16 flash_read16(const void __iomem *addr)
56 {
57 return __raw_readw(addr);
58 }
59
flash_write16(u16 d,void __iomem * addr)60 static 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
ixp4xx_read16(struct map_info * map,unsigned long ofs)69 static 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 */
ixp4xx_copy_from(struct map_info * map,void * to,unsigned long from,ssize_t len)82 static 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
ixp4xx_write16(struct map_info * map,map_word d,unsigned long adr)109 static 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
of_flash_probe_ixp4xx(struct platform_device * pdev,struct device_node * np,struct map_info * map)114 int 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