xref: /openbmc/linux/drivers/mtd/chips/map_rom.c (revision 3d40aed8)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Common code to handle map devices which are simple ROM
4  * (C) 2000 Red Hat.
5  */
6 
7 #include <linux/module.h>
8 #include <linux/types.h>
9 #include <linux/kernel.h>
10 #include <asm/io.h>
11 #include <asm/byteorder.h>
12 #include <linux/errno.h>
13 #include <linux/slab.h>
14 #include <linux/init.h>
15 #include <linux/of.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/mtd/map.h>
18 
19 static int maprom_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
20 static int maprom_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
21 static void maprom_nop (struct mtd_info *);
22 static struct mtd_info *map_rom_probe(struct map_info *map);
23 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info);
24 static int maprom_point (struct mtd_info *mtd, loff_t from, size_t len,
25 			 size_t *retlen, void **virt, resource_size_t *phys);
26 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
27 
28 
29 static struct mtd_chip_driver maprom_chipdrv = {
30 	.probe	= map_rom_probe,
31 	.name	= "map_rom",
32 	.module	= THIS_MODULE
33 };
34 
35 static unsigned int default_erasesize(struct map_info *map)
36 {
37 	const __be32 *erase_size = NULL;
38 
39 	erase_size = of_get_property(map->device_node, "erase-size", NULL);
40 
41 	return !erase_size ? map->size : be32_to_cpu(*erase_size);
42 }
43 
44 static struct mtd_info *map_rom_probe(struct map_info *map)
45 {
46 	struct mtd_info *mtd;
47 
48 	mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
49 	if (!mtd)
50 		return NULL;
51 
52 	map->fldrv = &maprom_chipdrv;
53 	mtd->priv = map;
54 	mtd->name = map->name;
55 	mtd->type = MTD_ROM;
56 	mtd->size = map->size;
57 	mtd->_point = maprom_point;
58 	mtd->_unpoint = maprom_unpoint;
59 	mtd->_read = maprom_read;
60 	mtd->_write = maprom_write;
61 	mtd->_sync = maprom_nop;
62 	mtd->_erase = maprom_erase;
63 	mtd->flags = MTD_CAP_ROM;
64 	mtd->erasesize = default_erasesize(map);
65 	mtd->writesize = 1;
66 	mtd->writebufsize = 1;
67 
68 	__module_get(THIS_MODULE);
69 	return mtd;
70 }
71 
72 
73 static int maprom_point(struct mtd_info *mtd, loff_t from, size_t len,
74 			size_t *retlen, void **virt, resource_size_t *phys)
75 {
76 	struct map_info *map = mtd->priv;
77 
78 	if (!map->virt)
79 		return -EINVAL;
80 	*virt = map->virt + from;
81 	if (phys)
82 		*phys = map->phys + from;
83 	*retlen = len;
84 	return 0;
85 }
86 
87 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
88 {
89 	return 0;
90 }
91 
92 static int maprom_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
93 {
94 	struct map_info *map = mtd->priv;
95 
96 	map_copy_from(map, buf, from, len);
97 	*retlen = len;
98 	return 0;
99 }
100 
101 static void maprom_nop(struct mtd_info *mtd)
102 {
103 	/* Nothing to see here */
104 }
105 
106 static int maprom_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
107 {
108 	return -EROFS;
109 }
110 
111 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info)
112 {
113 	/* We do our best 8) */
114 	return -EROFS;
115 }
116 
117 static int __init map_rom_init(void)
118 {
119 	register_mtd_chip_driver(&maprom_chipdrv);
120 	return 0;
121 }
122 
123 static void __exit map_rom_exit(void)
124 {
125 	unregister_mtd_chip_driver(&maprom_chipdrv);
126 }
127 
128 module_init(map_rom_init);
129 module_exit(map_rom_exit);
130 
131 MODULE_LICENSE("GPL");
132 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
133 MODULE_DESCRIPTION("MTD chip driver for ROM chips");
134