1 /*======================================================================
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).
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>
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
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).
27 Jochen Schaeuble <psionic@psionic.de>
29 ======================================================================*/
32 #include <linux/module.h>
33 #include <asm/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>
42 #include <linux/ioctl.h>
43 #include <linux/init.h>
45 #include <asm/system.h>
47 #include <linux/mtd/mtd.h>
49 #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */
50 #define SLRAM_BLK_SZ 0x4000
52 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
53 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
55 typedef struct slram_priv
{
60 typedef struct slram_mtd_list
{
61 struct mtd_info
*mtdinfo
;
62 struct slram_mtd_list
*next
;
66 static char *map
[SLRAM_MAX_DEVICES_PARAMS
];
68 module_param_array(map
, charp
, NULL
, 0);
69 MODULE_PARM_DESC(map
, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
74 static slram_mtd_list_t
*slram_mtdlist
= NULL
;
76 static int slram_erase(struct mtd_info
*, struct erase_info
*);
77 static int slram_point(struct mtd_info
*, loff_t
, size_t, size_t *, void **,
79 static void slram_unpoint(struct mtd_info
*, loff_t
, size_t);
80 static int slram_read(struct mtd_info
*, loff_t
, size_t, size_t *, u_char
*);
81 static int slram_write(struct mtd_info
*, loff_t
, size_t, size_t *, const u_char
*);
83 static int slram_erase(struct mtd_info
*mtd
, struct erase_info
*instr
)
85 slram_priv_t
*priv
= mtd
->priv
;
87 if (instr
->addr
+ instr
->len
> mtd
->size
) {
91 memset(priv
->start
+ instr
->addr
, 0xff, instr
->len
);
93 /* This'll catch a few races. Free the thing before returning :)
94 * I don't feel at all ashamed. This kind of thing is possible anyway
95 * with flash, but unlikely.
98 instr
->state
= MTD_ERASE_DONE
;
100 mtd_erase_callback(instr
);
105 static int slram_point(struct mtd_info
*mtd
, loff_t from
, size_t len
,
106 size_t *retlen
, void **virt
, resource_size_t
*phys
)
108 slram_priv_t
*priv
= mtd
->priv
;
110 /* can we return a physical address with this driver? */
114 if (from
+ len
> mtd
->size
)
117 *virt
= priv
->start
+ from
;
122 static void slram_unpoint(struct mtd_info
*mtd
, loff_t from
, size_t len
)
126 static int slram_read(struct mtd_info
*mtd
, loff_t from
, size_t len
,
127 size_t *retlen
, u_char
*buf
)
129 slram_priv_t
*priv
= mtd
->priv
;
131 if (from
> mtd
->size
)
134 if (from
+ len
> mtd
->size
)
135 len
= mtd
->size
- from
;
137 memcpy(buf
, priv
->start
+ from
, len
);
143 static int slram_write(struct mtd_info
*mtd
, loff_t to
, size_t len
,
144 size_t *retlen
, const u_char
*buf
)
146 slram_priv_t
*priv
= mtd
->priv
;
148 if (to
+ len
> mtd
->size
)
151 memcpy(priv
->start
+ to
, buf
, len
);
157 /*====================================================================*/
159 static int register_device(char *name
, unsigned long start
, unsigned long length
)
161 slram_mtd_list_t
**curmtd
;
163 curmtd
= &slram_mtdlist
;
165 curmtd
= &(*curmtd
)->next
;
168 *curmtd
= kmalloc(sizeof(slram_mtd_list_t
), GFP_KERNEL
);
170 E("slram: Cannot allocate new MTD device.\n");
173 (*curmtd
)->mtdinfo
= kzalloc(sizeof(struct mtd_info
), GFP_KERNEL
);
174 (*curmtd
)->next
= NULL
;
176 if ((*curmtd
)->mtdinfo
) {
177 (*curmtd
)->mtdinfo
->priv
=
178 kzalloc(sizeof(slram_priv_t
), GFP_KERNEL
);
180 if (!(*curmtd
)->mtdinfo
->priv
) {
181 kfree((*curmtd
)->mtdinfo
);
182 (*curmtd
)->mtdinfo
= NULL
;
186 if (!(*curmtd
)->mtdinfo
) {
187 E("slram: Cannot allocate new MTD device.\n");
191 if (!(((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->start
=
192 ioremap(start
, length
))) {
193 E("slram: ioremap failed\n");
196 ((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->end
=
197 ((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->start
+ length
;
200 (*curmtd
)->mtdinfo
->name
= name
;
201 (*curmtd
)->mtdinfo
->size
= length
;
202 (*curmtd
)->mtdinfo
->flags
= MTD_CAP_RAM
;
203 (*curmtd
)->mtdinfo
->erase
= slram_erase
;
204 (*curmtd
)->mtdinfo
->point
= slram_point
;
205 (*curmtd
)->mtdinfo
->unpoint
= slram_unpoint
;
206 (*curmtd
)->mtdinfo
->read
= slram_read
;
207 (*curmtd
)->mtdinfo
->write
= slram_write
;
208 (*curmtd
)->mtdinfo
->owner
= THIS_MODULE
;
209 (*curmtd
)->mtdinfo
->type
= MTD_RAM
;
210 (*curmtd
)->mtdinfo
->erasesize
= SLRAM_BLK_SZ
;
211 (*curmtd
)->mtdinfo
->writesize
= 1;
213 if (add_mtd_device((*curmtd
)->mtdinfo
)) {
214 E("slram: Failed to register new device\n");
215 iounmap(((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->start
);
216 kfree((*curmtd
)->mtdinfo
->priv
);
217 kfree((*curmtd
)->mtdinfo
);
220 T("slram: Registered device %s from %luKiB to %luKiB\n", name
,
221 (start
/ 1024), ((start
+ length
) / 1024));
222 T("slram: Mapped from 0x%p to 0x%p\n",
223 ((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->start
,
224 ((slram_priv_t
*)(*curmtd
)->mtdinfo
->priv
)->end
);
228 static void unregister_devices(void)
230 slram_mtd_list_t
*nextitem
;
232 while (slram_mtdlist
) {
233 nextitem
= slram_mtdlist
->next
;
234 del_mtd_device(slram_mtdlist
->mtdinfo
);
235 iounmap(((slram_priv_t
*)slram_mtdlist
->mtdinfo
->priv
)->start
);
236 kfree(slram_mtdlist
->mtdinfo
->priv
);
237 kfree(slram_mtdlist
->mtdinfo
);
238 kfree(slram_mtdlist
);
239 slram_mtdlist
= nextitem
;
243 static unsigned long handle_unit(unsigned long value
, char *unit
)
245 if ((*unit
== 'M') || (*unit
== 'm')) {
246 return(value
* 1024 * 1024);
247 } else if ((*unit
== 'K') || (*unit
== 'k')) {
248 return(value
* 1024);
253 static int parse_cmdline(char *devname
, char *szstart
, char *szlength
)
256 unsigned long devstart
;
257 unsigned long devlength
;
259 if ((!devname
) || (!szstart
) || (!szlength
)) {
260 unregister_devices();
264 devstart
= simple_strtoul(szstart
, &buffer
, 0);
265 devstart
= handle_unit(devstart
, buffer
);
267 if (*(szlength
) != '+') {
268 devlength
= simple_strtoul(szlength
, &buffer
, 0);
269 devlength
= handle_unit(devlength
, buffer
) - devstart
;
270 if (devlength
< devstart
)
273 devlength
-= devstart
;
275 devlength
= simple_strtoul(szlength
+ 1, &buffer
, 0);
276 devlength
= handle_unit(devlength
, buffer
);
278 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
279 devname
, devstart
, devlength
);
280 if (devlength
% SLRAM_BLK_SZ
!= 0)
283 if ((devstart
= register_device(devname
, devstart
, devlength
))){
284 unregister_devices();
285 return((int)devstart
);
290 E("slram: Illegal length parameter.\n");
296 static int __init
mtd_slram_setup(char *str
)
302 __setup("slram=", mtd_slram_setup
);
306 static int __init
init_slram(void)
318 E("slram: not enough parameters.\n");
322 devname
= devstart
= devlength
= NULL
;
324 if (!(devname
= strsep(&map
, ","))) {
325 E("slram: No devicename specified.\n");
328 T("slram: devname = %s\n", devname
);
329 if ((!map
) || (!(devstart
= strsep(&map
, ",")))) {
330 E("slram: No devicestart specified.\n");
332 T("slram: devstart = %s\n", devstart
);
333 if ((!map
) || (!(devlength
= strsep(&map
, ",")))) {
334 E("slram: No devicelength / -end specified.\n");
336 T("slram: devlength = %s\n", devlength
);
337 if (parse_cmdline(devname
, devstart
, devlength
) != 0) {
344 for (count
= 0; count
< SLRAM_MAX_DEVICES_PARAMS
&& map
[count
];
348 if ((count
% 3 != 0) || (count
== 0)) {
349 E("slram: not enough parameters.\n");
352 for (i
= 0; i
< (count
/ 3); i
++) {
353 devname
= map
[i
* 3];
355 if (parse_cmdline(devname
, map
[i
* 3 + 1], map
[i
* 3 + 2])!=0) {
365 static void __exit
cleanup_slram(void)
367 unregister_devices();
370 module_init(init_slram
);
371 module_exit(cleanup_slram
);
373 MODULE_LICENSE("GPL");
374 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
375 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
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