1 /*
2  * mtdram - a test mtd device
3  * Author: Alexander Larsson <alex@cendio.se>
4  *
5  * Copyright (c) 1999 Alexander Larsson <alex@cendio.se>
6  * Copyright (c) 2005 Joern Engel <joern@wh.fh-wedel.de>
7  *
8  * This code is GPL
9  *
10  */
11 
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/ioport.h>
15 #include <linux/vmalloc.h>
16 #include <linux/mm.h>
17 #include <linux/init.h>
18 #include <linux/mtd/mtd.h>
19 #include <linux/mtd/mtdram.h>
20 
21 static unsigned long total_size = CONFIG_MTDRAM_TOTAL_SIZE;
22 static unsigned long erase_size = CONFIG_MTDRAM_ERASE_SIZE;
23 static unsigned long writebuf_size = 64;
24 #define MTDRAM_TOTAL_SIZE (total_size * 1024)
25 #define MTDRAM_ERASE_SIZE (erase_size * 1024)
26 
27 module_param(total_size, ulong, 0);
28 MODULE_PARM_DESC(total_size, "Total device size in KiB");
29 module_param(erase_size, ulong, 0);
30 MODULE_PARM_DESC(erase_size, "Device erase block size in KiB");
31 module_param(writebuf_size, ulong, 0);
32 MODULE_PARM_DESC(writebuf_size, "Device write buf size in Bytes (Default: 64)");
33 
34 // We could store these in the mtd structure, but we only support 1 device..
35 static struct mtd_info *mtd_info;
36 
check_offs_len(struct mtd_info * mtd,loff_t ofs,uint64_t len)37 static int check_offs_len(struct mtd_info *mtd, loff_t ofs, uint64_t len)
38 {
39 	int ret = 0;
40 
41 	/* Start address must align on block boundary */
42 	if (mtd_mod_by_eb(ofs, mtd)) {
43 		pr_debug("%s: unaligned address\n", __func__);
44 		ret = -EINVAL;
45 	}
46 
47 	/* Length must align on block boundary */
48 	if (mtd_mod_by_eb(len, mtd)) {
49 		pr_debug("%s: length not block aligned\n", __func__);
50 		ret = -EINVAL;
51 	}
52 
53 	return ret;
54 }
55 
ram_erase(struct mtd_info * mtd,struct erase_info * instr)56 static int ram_erase(struct mtd_info *mtd, struct erase_info *instr)
57 {
58 	if (check_offs_len(mtd, instr->addr, instr->len))
59 		return -EINVAL;
60 	memset((char *)mtd->priv + instr->addr, 0xff, instr->len);
61 
62 	return 0;
63 }
64 
ram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,void ** virt,resource_size_t * phys)65 static int ram_point(struct mtd_info *mtd, loff_t from, size_t len,
66 		size_t *retlen, void **virt, resource_size_t *phys)
67 {
68 	*virt = mtd->priv + from;
69 	*retlen = len;
70 
71 	if (phys) {
72 		/* limit retlen to the number of contiguous physical pages */
73 		unsigned long page_ofs = offset_in_page(*virt);
74 		void *addr = *virt - page_ofs;
75 		unsigned long pfn1, pfn0 = vmalloc_to_pfn(addr);
76 
77 		*phys = __pfn_to_phys(pfn0) + page_ofs;
78 		len += page_ofs;
79 		while (len > PAGE_SIZE) {
80 			len -= PAGE_SIZE;
81 			addr += PAGE_SIZE;
82 			pfn0++;
83 			pfn1 = vmalloc_to_pfn(addr);
84 			if (pfn1 != pfn0) {
85 				*retlen = addr - *virt;
86 				break;
87 			}
88 		}
89 	}
90 
91 	return 0;
92 }
93 
ram_unpoint(struct mtd_info * mtd,loff_t from,size_t len)94 static int ram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
95 {
96 	return 0;
97 }
98 
ram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)99 static int ram_read(struct mtd_info *mtd, loff_t from, size_t len,
100 		size_t *retlen, u_char *buf)
101 {
102 	memcpy(buf, mtd->priv + from, len);
103 	*retlen = len;
104 	return 0;
105 }
106 
ram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)107 static int ram_write(struct mtd_info *mtd, loff_t to, size_t len,
108 		size_t *retlen, const u_char *buf)
109 {
110 	memcpy((char *)mtd->priv + to, buf, len);
111 	*retlen = len;
112 	return 0;
113 }
114 
cleanup_mtdram(void)115 static void __exit cleanup_mtdram(void)
116 {
117 	if (mtd_info) {
118 		mtd_device_unregister(mtd_info);
119 		vfree(mtd_info->priv);
120 		kfree(mtd_info);
121 	}
122 }
123 
mtdram_init_device(struct mtd_info * mtd,void * mapped_address,unsigned long size,const char * name)124 int mtdram_init_device(struct mtd_info *mtd, void *mapped_address,
125 		unsigned long size, const char *name)
126 {
127 	memset(mtd, 0, sizeof(*mtd));
128 
129 	/* Setup the MTD structure */
130 	mtd->name = name;
131 	mtd->type = MTD_RAM;
132 	mtd->flags = MTD_CAP_RAM;
133 	mtd->size = size;
134 	mtd->writesize = 1;
135 	mtd->writebufsize = writebuf_size;
136 	mtd->erasesize = MTDRAM_ERASE_SIZE;
137 	mtd->priv = mapped_address;
138 
139 	mtd->owner = THIS_MODULE;
140 	mtd->_erase = ram_erase;
141 	mtd->_point = ram_point;
142 	mtd->_unpoint = ram_unpoint;
143 	mtd->_read = ram_read;
144 	mtd->_write = ram_write;
145 
146 	if (mtd_device_register(mtd, NULL, 0))
147 		return -EIO;
148 
149 	return 0;
150 }
151 
init_mtdram(void)152 static int __init init_mtdram(void)
153 {
154 	void *addr;
155 	int err;
156 
157 	if (!total_size)
158 		return -EINVAL;
159 
160 	/* Allocate some memory */
161 	mtd_info = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
162 	if (!mtd_info)
163 		return -ENOMEM;
164 
165 	addr = vmalloc(MTDRAM_TOTAL_SIZE);
166 	if (!addr) {
167 		kfree(mtd_info);
168 		mtd_info = NULL;
169 		return -ENOMEM;
170 	}
171 	err = mtdram_init_device(mtd_info, addr, MTDRAM_TOTAL_SIZE, "mtdram test device");
172 	if (err) {
173 		vfree(addr);
174 		kfree(mtd_info);
175 		mtd_info = NULL;
176 		return err;
177 	}
178 	memset(mtd_info->priv, 0xff, MTDRAM_TOTAL_SIZE);
179 	return err;
180 }
181 
182 module_init(init_mtdram);
183 module_exit(cleanup_mtdram);
184 
185 MODULE_LICENSE("GPL");
186 MODULE_AUTHOR("Alexander Larsson <alexl@redhat.com>");
187 MODULE_DESCRIPTION("Simulated MTD driver for testing");
188