1 /*======================================================================
2
3 $Id: slram.c,v 1.28 2003/01/24 13:35:34 dwmw2 Exp $
4
5 This driver provides a method to access memory not used by the kernel
6 itself (i.e. if the kernel commandline mem=xxx is used). To actually
7 use slram at least mtdblock or mtdchar is required (for block or
8 character device access).
9
10 Usage:
11
12 if compiled as loadable module:
13 modprobe slram map=<name>,<start>,<end/offset>
14 if statically linked into the kernel use the following kernel cmd.line
15 slram=<name>,<start>,<end/offset>
16
17 <name>: name of the device that will be listed in /proc/mtd
18 <start>: start of the memory region, decimal or hex (0xabcdef)
19 <end/offset>: end of the memory region. It's possible to use +0x1234
20 to specify the offset instead of the absolute address
21
22 NOTE:
23 With slram it's only possible to map a contigous memory region. Therfore
24 if there's a device mapped somewhere in the region specified slram will
25 fail to load (see kernel log if modprobe fails).
26
27 -
28
29 Jochen Schaeuble <psionic@psionic.de>
30
31 ======================================================================*/
32
33
34 #include <linux/module.h>
35 #include <asm/uaccess.h>
36 #include <linux/types.h>
37 #include <linux/kernel.h>
38 #include <linux/sched.h>
39 #include <linux/ptrace.h>
40 #include <linux/slab.h>
41 #include <linux/string.h>
42 #include <linux/timer.h>
43 #include <linux/major.h>
44 #include <linux/fs.h>
45 #include <linux/ioctl.h>
46 #include <linux/init.h>
47 #include <asm/io.h>
48 #include <asm/system.h>
49
50 #include <linux/mtd/mtd.h>
51
52 #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */
53
54 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
55 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
56
57 typedef struct slram_priv {
58 u_char *start;
59 u_char *end;
60 } slram_priv_t;
61
62 typedef struct slram_mtd_list {
63 struct mtd_info *mtdinfo;
64 struct slram_mtd_list *next;
65 } slram_mtd_list_t;
66
67 #ifdef MODULE
68 static char *map[SLRAM_MAX_DEVICES_PARAMS];
69 #else
70 static char *map;
71 #endif
72
73 MODULE_PARM(map, "3-" __MODULE_STRING(SLRAM_MAX_DEVICES_PARAMS) "s");
74 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
75
76 static slram_mtd_list_t *slram_mtdlist = NULL;
77
78 int slram_erase(struct mtd_info *, struct erase_info *);
79 int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **);
80 void slram_unpoint(struct mtd_info *, u_char *, loff_t, size_t);
81 int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
82 int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
83
slram_erase(struct mtd_info * mtd,struct erase_info * instr)84 int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
85 {
86 slram_priv_t *priv = mtd->priv;
87
88 if (instr->addr + instr->len > mtd->size) {
89 return(-EINVAL);
90 }
91
92 memset(priv->start + instr->addr, 0xff, instr->len);
93
94 /* This'll catch a few races. Free the thing before returning :)
95 * I don't feel at all ashamed. This kind of thing is possible anyway
96 * with flash, but unlikely.
97 */
98
99 instr->state = MTD_ERASE_DONE;
100
101 if (instr->callback) {
102 (*(instr->callback))(instr);
103 }
104 else {
105 kfree(instr);
106 }
107
108 return(0);
109 }
110
slram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char ** mtdbuf)111 int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
112 size_t *retlen, u_char **mtdbuf)
113 {
114 slram_priv_t *priv = (slram_priv_t *)mtd->priv;
115
116 *mtdbuf = priv->start + from;
117 *retlen = len;
118 return(0);
119 }
120
slram_unpoint(struct mtd_info * mtd,u_char * addr,loff_t from,size_t len)121 void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
122 {
123 }
124
slram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)125 int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
126 size_t *retlen, u_char *buf)
127 {
128 slram_priv_t *priv = (slram_priv_t *)mtd->priv;
129
130 memcpy(buf, priv->start + from, len);
131
132 *retlen = len;
133 return(0);
134 }
135
slram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)136 int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
137 size_t *retlen, const u_char *buf)
138 {
139 slram_priv_t *priv = (slram_priv_t *)mtd->priv;
140
141 memcpy(priv->start + to, buf, len);
142
143 *retlen = len;
144 return(0);
145 }
146
147 /*====================================================================*/
148
register_device(char * name,unsigned long start,unsigned long length)149 int register_device(char *name, unsigned long start, unsigned long length)
150 {
151 slram_mtd_list_t **curmtd;
152
153 curmtd = &slram_mtdlist;
154 while (*curmtd) {
155 curmtd = &(*curmtd)->next;
156 }
157
158 *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
159 if (!(*curmtd)) {
160 E("slram: Cannot allocate new MTD device.\n");
161 return(-ENOMEM);
162 }
163 (*curmtd)->mtdinfo = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
164 (*curmtd)->next = NULL;
165
166 if ((*curmtd)->mtdinfo) {
167 memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));
168 (*curmtd)->mtdinfo->priv =
169 (void *)kmalloc(sizeof(slram_priv_t), GFP_KERNEL);
170
171 if (!(*curmtd)->mtdinfo->priv) {
172 kfree((*curmtd)->mtdinfo);
173 (*curmtd)->mtdinfo = NULL;
174 } else {
175 memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));
176 }
177 }
178
179 if (!(*curmtd)->mtdinfo) {
180 E("slram: Cannot allocate new MTD device.\n");
181 return(-ENOMEM);
182 }
183
184 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
185 ioremap(start, length))) {
186 E("slram: ioremap failed\n");
187 return -EIO;
188 }
189 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
190 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
191
192
193 (*curmtd)->mtdinfo->name = name;
194 (*curmtd)->mtdinfo->size = length;
195 (*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS |
196 MTD_WRITEB_WRITEABLE | MTD_VOLATILE;
197 (*curmtd)->mtdinfo->erase = slram_erase;
198 (*curmtd)->mtdinfo->point = slram_point;
199 (*curmtd)->mtdinfo->unpoint = slram_unpoint;
200 (*curmtd)->mtdinfo->read = slram_read;
201 (*curmtd)->mtdinfo->write = slram_write;
202 (*curmtd)->mtdinfo->module = THIS_MODULE;
203 (*curmtd)->mtdinfo->type = MTD_RAM;
204 (*curmtd)->mtdinfo->erasesize = 0x0;
205
206 if (add_mtd_device((*curmtd)->mtdinfo)) {
207 E("slram: Failed to register new device\n");
208 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
209 kfree((*curmtd)->mtdinfo->priv);
210 kfree((*curmtd)->mtdinfo);
211 return(-EAGAIN);
212 }
213 T("slram: Registered device %s from %luKiB to %luKiB\n", name,
214 (start / 1024), ((start + length) / 1024));
215 T("slram: Mapped from 0x%p to 0x%p\n",
216 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
217 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
218 return(0);
219 }
220
unregister_devices(void)221 void unregister_devices(void)
222 {
223 slram_mtd_list_t *nextitem;
224
225 while (slram_mtdlist) {
226 nextitem = slram_mtdlist->next;
227 del_mtd_device(slram_mtdlist->mtdinfo);
228 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
229 kfree(slram_mtdlist->mtdinfo->priv);
230 kfree(slram_mtdlist->mtdinfo);
231 kfree(slram_mtdlist);
232 slram_mtdlist = nextitem;
233 }
234 }
235
handle_unit(unsigned long value,char * unit)236 unsigned long handle_unit(unsigned long value, char *unit)
237 {
238 if ((*unit == 'M') || (*unit == 'm')) {
239 return(value * 1024 * 1024);
240 } else if ((*unit == 'K') || (*unit == 'k')) {
241 return(value * 1024);
242 }
243 return(value);
244 }
245
parse_cmdline(char * devname,char * szstart,char * szlength)246 int parse_cmdline(char *devname, char *szstart, char *szlength)
247 {
248 char *buffer;
249 unsigned long devstart;
250 unsigned long devlength;
251
252 if ((!devname) || (!szstart) || (!szlength)) {
253 unregister_devices();
254 return(-EINVAL);
255 }
256
257 devstart = simple_strtoul(szstart, &buffer, 0);
258 devstart = handle_unit(devstart, buffer);
259
260 if (*(szlength) != '+') {
261 devlength = simple_strtoul(szlength, &buffer, 0);
262 devlength = handle_unit(devlength, buffer) - devstart;
263 } else {
264 devlength = simple_strtoul(szlength + 1, &buffer, 0);
265 devlength = handle_unit(devlength, buffer);
266 }
267 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
268 devname, devstart, devlength);
269 if ((devstart < 0) || (devlength < 0)) {
270 E("slram: Illegal start / length parameter.\n");
271 return(-EINVAL);
272 }
273
274 if ((devstart = register_device(devname, devstart, devlength))){
275 unregister_devices();
276 return((int)devstart);
277 }
278 return(0);
279 }
280
281 #ifndef MODULE
282
mtd_slram_setup(char * str)283 static int __init mtd_slram_setup(char *str)
284 {
285 map = str;
286 return(1);
287 }
288
289 __setup("slram=", mtd_slram_setup);
290
291 #endif
292
init_slram(void)293 int init_slram(void)
294 {
295 char *devname;
296 int i;
297
298 #ifndef MODULE
299 char *devstart;
300 char *devlength;
301
302 i = 0;
303
304 if (!map) {
305 E("slram: not enough parameters.\n");
306 return(-EINVAL);
307 }
308 while (map) {
309 devname = devstart = devlength = NULL;
310
311 if (!(devname = strsep(&map, ","))) {
312 E("slram: No devicename specified.\n");
313 break;
314 }
315 T("slram: devname = %s\n", devname);
316 if ((!map) || (!(devstart = strsep(&map, ",")))) {
317 E("slram: No devicestart specified.\n");
318 }
319 T("slram: devstart = %s\n", devstart);
320 if ((!map) || (!(devlength = strsep(&map, ",")))) {
321 E("slram: No devicelength / -end specified.\n");
322 }
323 T("slram: devlength = %s\n", devlength);
324 if (parse_cmdline(devname, devstart, devlength) != 0) {
325 return(-EINVAL);
326 }
327 }
328 #else
329 int count;
330
331 for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
332 count++) {
333 }
334
335 if ((count % 3 != 0) || (count == 0)) {
336 E("slram: not enough parameters.\n");
337 return(-EINVAL);
338 }
339 for (i = 0; i < (count / 3); i++) {
340 devname = map[i * 3];
341
342 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
343 return(-EINVAL);
344 }
345
346 }
347 #endif /* !MODULE */
348
349 return(0);
350 }
351
cleanup_slram(void)352 static void __exit cleanup_slram(void)
353 {
354 unregister_devices();
355 }
356
357 module_init(init_slram);
358 module_exit(cleanup_slram);
359
360 MODULE_LICENSE("GPL");
361 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
362 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
363