1 /*======================================================================
2
3 This driver provides a method to access memory not used by the kernel
4 itself (i.e. if the kernel commandline mem=xxx is used). To actually
5 use slram at least mtdblock or mtdchar is required (for block or
6 character device access).
7
8 Usage:
9
10 if compiled as loadable module:
11 modprobe slram map=<name>,<start>,<end/offset>
12 if statically linked into the kernel use the following kernel cmd.line
13 slram=<name>,<start>,<end/offset>
14
15 <name>: name of the device that will be listed in /proc/mtd
16 <start>: start of the memory region, decimal or hex (0xabcdef)
17 <end/offset>: end of the memory region. It's possible to use +0x1234
18 to specify the offset instead of the absolute address
19
20 NOTE:
21 With slram it's only possible to map a contiguous memory region. Therefore
22 if there's a device mapped somewhere in the region specified slram will
23 fail to load (see kernel log if modprobe fails).
24
25 -
26
27 Jochen Schaeuble <psionic@psionic.de>
28
29 ======================================================================*/
30
31
32 #include <linux/module.h>
33 #include <linux/uaccess.h>
34 #include <linux/types.h>
35 #include <linux/kernel.h>
36 #include <linux/ptrace.h>
37 #include <linux/slab.h>
38 #include <linux/string.h>
39 #include <linux/timer.h>
40 #include <linux/major.h>
41 #include <linux/fs.h>
42 #include <linux/ioctl.h>
43 #include <linux/init.h>
44 #include <linux/io.h>
45
46 #include <linux/mtd/mtd.h>
47
48 #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */
49 #define SLRAM_BLK_SZ 0x4000
50
51 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
52 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
53
54 typedef struct slram_priv {
55 u_char *start;
56 u_char *end;
57 } slram_priv_t;
58
59 typedef struct slram_mtd_list {
60 struct mtd_info *mtdinfo;
61 struct slram_mtd_list *next;
62 } slram_mtd_list_t;
63
64 #ifdef MODULE
65 static char *map[SLRAM_MAX_DEVICES_PARAMS];
66
67 module_param_array(map, charp, NULL, 0);
68 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
69 #else
70 static char *map;
71 #endif
72
73 static slram_mtd_list_t *slram_mtdlist = NULL;
74
75 static int slram_erase(struct mtd_info *, struct erase_info *);
76 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
77 resource_size_t *);
78 static int slram_unpoint(struct mtd_info *, loff_t, size_t);
79 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
80 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
81
slram_erase(struct mtd_info * mtd,struct erase_info * instr)82 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
83 {
84 slram_priv_t *priv = mtd->priv;
85
86 memset(priv->start + instr->addr, 0xff, instr->len);
87
88 return(0);
89 }
90
slram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,void ** virt,resource_size_t * phys)91 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
92 size_t *retlen, void **virt, resource_size_t *phys)
93 {
94 slram_priv_t *priv = mtd->priv;
95
96 *virt = priv->start + from;
97 *retlen = len;
98 return(0);
99 }
100
slram_unpoint(struct mtd_info * mtd,loff_t from,size_t len)101 static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
102 {
103 return 0;
104 }
105
slram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)106 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
107 size_t *retlen, u_char *buf)
108 {
109 slram_priv_t *priv = mtd->priv;
110
111 memcpy(buf, priv->start + from, len);
112 *retlen = len;
113 return(0);
114 }
115
slram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)116 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
117 size_t *retlen, const u_char *buf)
118 {
119 slram_priv_t *priv = mtd->priv;
120
121 memcpy(priv->start + to, buf, len);
122 *retlen = len;
123 return(0);
124 }
125
126 /*====================================================================*/
127
register_device(char * name,unsigned long start,unsigned long length)128 static int register_device(char *name, unsigned long start, unsigned long length)
129 {
130 slram_mtd_list_t **curmtd;
131
132 curmtd = &slram_mtdlist;
133 while (*curmtd) {
134 curmtd = &(*curmtd)->next;
135 }
136
137 *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
138 if (!(*curmtd)) {
139 E("slram: Cannot allocate new MTD device.\n");
140 return(-ENOMEM);
141 }
142 (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
143 (*curmtd)->next = NULL;
144
145 if ((*curmtd)->mtdinfo) {
146 (*curmtd)->mtdinfo->priv =
147 kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
148
149 if (!(*curmtd)->mtdinfo->priv) {
150 kfree((*curmtd)->mtdinfo);
151 (*curmtd)->mtdinfo = NULL;
152 }
153 }
154
155 if (!(*curmtd)->mtdinfo) {
156 E("slram: Cannot allocate new MTD device.\n");
157 return(-ENOMEM);
158 }
159
160 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
161 memremap(start, length,
162 MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) {
163 E("slram: memremap failed\n");
164 return -EIO;
165 }
166 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
167 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
168
169
170 (*curmtd)->mtdinfo->name = name;
171 (*curmtd)->mtdinfo->size = length;
172 (*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
173 (*curmtd)->mtdinfo->_erase = slram_erase;
174 (*curmtd)->mtdinfo->_point = slram_point;
175 (*curmtd)->mtdinfo->_unpoint = slram_unpoint;
176 (*curmtd)->mtdinfo->_read = slram_read;
177 (*curmtd)->mtdinfo->_write = slram_write;
178 (*curmtd)->mtdinfo->owner = THIS_MODULE;
179 (*curmtd)->mtdinfo->type = MTD_RAM;
180 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
181 (*curmtd)->mtdinfo->writesize = 1;
182
183 if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0)) {
184 E("slram: Failed to register new device\n");
185 memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
186 kfree((*curmtd)->mtdinfo->priv);
187 kfree((*curmtd)->mtdinfo);
188 return(-EAGAIN);
189 }
190 T("slram: Registered device %s from %luKiB to %luKiB\n", name,
191 (start / 1024), ((start + length) / 1024));
192 T("slram: Mapped from 0x%p to 0x%p\n",
193 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
194 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
195 return(0);
196 }
197
unregister_devices(void)198 static void unregister_devices(void)
199 {
200 slram_mtd_list_t *nextitem;
201
202 while (slram_mtdlist) {
203 nextitem = slram_mtdlist->next;
204 mtd_device_unregister(slram_mtdlist->mtdinfo);
205 memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
206 kfree(slram_mtdlist->mtdinfo->priv);
207 kfree(slram_mtdlist->mtdinfo);
208 kfree(slram_mtdlist);
209 slram_mtdlist = nextitem;
210 }
211 }
212
handle_unit(unsigned long value,char * unit)213 static unsigned long handle_unit(unsigned long value, char *unit)
214 {
215 if ((*unit == 'M') || (*unit == 'm')) {
216 return(value * 1024 * 1024);
217 } else if ((*unit == 'K') || (*unit == 'k')) {
218 return(value * 1024);
219 }
220 return(value);
221 }
222
parse_cmdline(char * devname,char * szstart,char * szlength)223 static int parse_cmdline(char *devname, char *szstart, char *szlength)
224 {
225 char *buffer;
226 unsigned long devstart;
227 unsigned long devlength;
228
229 if ((!devname) || (!szstart) || (!szlength)) {
230 unregister_devices();
231 return(-EINVAL);
232 }
233
234 devstart = simple_strtoul(szstart, &buffer, 0);
235 devstart = handle_unit(devstart, buffer);
236
237 if (*(szlength) != '+') {
238 devlength = simple_strtoul(szlength, &buffer, 0);
239 devlength = handle_unit(devlength, buffer);
240 if (devlength < devstart)
241 goto err_out;
242
243 devlength -= devstart;
244 } else {
245 devlength = simple_strtoul(szlength + 1, &buffer, 0);
246 devlength = handle_unit(devlength, buffer);
247 }
248 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
249 devname, devstart, devlength);
250 if (devlength % SLRAM_BLK_SZ != 0)
251 goto err_out;
252
253 if ((devstart = register_device(devname, devstart, devlength))){
254 unregister_devices();
255 return((int)devstart);
256 }
257 return(0);
258
259 err_out:
260 E("slram: Illegal length parameter.\n");
261 return(-EINVAL);
262 }
263
264 #ifndef MODULE
265
mtd_slram_setup(char * str)266 static int __init mtd_slram_setup(char *str)
267 {
268 map = str;
269 return(1);
270 }
271
272 __setup("slram=", mtd_slram_setup);
273
274 #endif
275
init_slram(void)276 static int __init init_slram(void)
277 {
278 char *devname;
279
280 #ifndef MODULE
281 char *devstart;
282 char *devlength;
283
284 if (!map) {
285 E("slram: not enough parameters.\n");
286 return(-EINVAL);
287 }
288 while (map) {
289 devname = devstart = devlength = NULL;
290
291 if (!(devname = strsep(&map, ","))) {
292 E("slram: No devicename specified.\n");
293 break;
294 }
295 T("slram: devname = %s\n", devname);
296 if ((!map) || (!(devstart = strsep(&map, ",")))) {
297 E("slram: No devicestart specified.\n");
298 }
299 T("slram: devstart = %s\n", devstart);
300 if ((!map) || (!(devlength = strsep(&map, ",")))) {
301 E("slram: No devicelength / -end specified.\n");
302 }
303 T("slram: devlength = %s\n", devlength);
304 if (parse_cmdline(devname, devstart, devlength) != 0) {
305 return(-EINVAL);
306 }
307 }
308 #else
309 int count;
310 int i;
311
312 for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
313 count++) {
314 }
315
316 if ((count % 3 != 0) || (count == 0)) {
317 E("slram: not enough parameters.\n");
318 return(-EINVAL);
319 }
320 for (i = 0; i < (count / 3); i++) {
321 devname = map[i * 3];
322
323 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
324 return(-EINVAL);
325 }
326
327 }
328 #endif /* !MODULE */
329
330 return(0);
331 }
332
cleanup_slram(void)333 static void __exit cleanup_slram(void)
334 {
335 unregister_devices();
336 }
337
338 module_init(init_slram);
339 module_exit(cleanup_slram);
340
341 MODULE_LICENSE("GPL");
342 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
343 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
344
