summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/devices/slram.c
blob: a425d09f35a02fd9f3fbd2f0ff9df68019ba11e3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
/*======================================================================

  This driver provides a method to access memory not used by the kernel
  itself (i.e. if the kernel commandline mem=xxx is used). To actually
  use slram at least mtdblock or mtdchar is required (for block or
  character device access).

  Usage:

  if compiled as loadable module:
    modprobe slram map=<name>,<start>,<end/offset>
  if statically linked into the kernel use the following kernel cmd.line
    slram=<name>,<start>,<end/offset>

  <name>: name of the device that will be listed in /proc/mtd
  <start>: start of the memory region, decimal or hex (0xabcdef)
  <end/offset>: end of the memory region. It's possible to use +0x1234
                to specify the offset instead of the absolute address

  NOTE:
  With slram it's only possible to map a contigous memory region. Therfore
  if there's a device mapped somewhere in the region specified slram will
  fail to load (see kernel log if modprobe fails).

  -

  Jochen Schaeuble <psionic@psionic.de>

======================================================================*/


#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/system.h>

#include <linux/mtd/mtd.h>

#define SLRAM_MAX_DEVICES_PARAMS 6		/* 3 parameters / device */
#define SLRAM_BLK_SZ 0x4000

#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)

typedef struct slram_priv {
	u_char *start;
	u_char *end;
} slram_priv_t;

typedef struct slram_mtd_list {
	struct mtd_info *mtdinfo;
	struct slram_mtd_list *next;
} slram_mtd_list_t;

#ifdef MODULE
static char *map[SLRAM_MAX_DEVICES_PARAMS];

module_param_array(map, charp, NULL, 0);
MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
#else
static char *map;
#endif

static slram_mtd_list_t *slram_mtdlist = NULL;

static int slram_erase(struct mtd_info *, struct erase_info *);
static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
		resource_size_t *);
static void slram_unpoint(struct mtd_info *, loff_t, size_t);
static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);

static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	slram_priv_t *priv = mtd->priv;

	if (instr->addr + instr->len > mtd->size) {
		return(-EINVAL);
	}

	memset(priv->start + instr->addr, 0xff, instr->len);

	/* This'll catch a few races. Free the thing before returning :)
	 * I don't feel at all ashamed. This kind of thing is possible anyway
	 * with flash, but unlikely.
	 */

	instr->state = MTD_ERASE_DONE;

	mtd_erase_callback(instr);

	return(0);
}

static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
		size_t *retlen, void **virt, resource_size_t *phys)
{
	slram_priv_t *priv = mtd->priv;

	/* can we return a physical address with this driver? */
	if (phys)
		return -EINVAL;

	if (from + len > mtd->size)
		return -EINVAL;

	*virt = priv->start + from;
	*retlen = len;
	return(0);
}

static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
}

static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
		size_t *retlen, u_char *buf)
{
	slram_priv_t *priv = mtd->priv;

	if (from > mtd->size)
		return -EINVAL;

	if (from + len > mtd->size)
		len = mtd->size - from;

	memcpy(buf, priv->start + from, len);

	*retlen = len;
	return(0);
}

static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
		size_t *retlen, const u_char *buf)
{
	slram_priv_t *priv = mtd->priv;

	if (to + len > mtd->size)
		return -EINVAL;

	memcpy(priv->start + to, buf, len);

	*retlen = len;
	return(0);
}

/*====================================================================*/

static int register_device(char *name, unsigned long start, unsigned long length)
{
	slram_mtd_list_t **curmtd;

	curmtd = &slram_mtdlist;
	while (*curmtd) {
		curmtd = &(*curmtd)->next;
	}

	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
	if (!(*curmtd)) {
		E("slram: Cannot allocate new MTD device.\n");
		return(-ENOMEM);
	}
	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
	(*curmtd)->next = NULL;

	if ((*curmtd)->mtdinfo)	{
		(*curmtd)->mtdinfo->priv =
			kzalloc(sizeof(slram_priv_t), GFP_KERNEL);

		if (!(*curmtd)->mtdinfo->priv) {
			kfree((*curmtd)->mtdinfo);
			(*curmtd)->mtdinfo = NULL;
		}
	}

	if (!(*curmtd)->mtdinfo) {
		E("slram: Cannot allocate new MTD device.\n");
		return(-ENOMEM);
	}

	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
				ioremap(start, length))) {
		E("slram: ioremap failed\n");
		return -EIO;
	}
	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;


	(*curmtd)->mtdinfo->name = name;
	(*curmtd)->mtdinfo->size = length;
	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
        (*curmtd)->mtdinfo->erase = slram_erase;
	(*curmtd)->mtdinfo->point = slram_point;
	(*curmtd)->mtdinfo->unpoint = slram_unpoint;
	(*curmtd)->mtdinfo->read = slram_read;
	(*curmtd)->mtdinfo->write = slram_write;
	(*curmtd)->mtdinfo->owner = THIS_MODULE;
	(*curmtd)->mtdinfo->type = MTD_RAM;
	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
	(*curmtd)->mtdinfo->writesize = 1;

	if (add_mtd_device((*curmtd)->mtdinfo))	{
		E("slram: Failed to register new device\n");
		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
		kfree((*curmtd)->mtdinfo->priv);
		kfree((*curmtd)->mtdinfo);
		return(-EAGAIN);
	}
	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
			(start / 1024), ((start + length) / 1024));
	T("slram: Mapped from 0x%p to 0x%p\n",
			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
	return(0);
}

static void unregister_devices(void)
{
	slram_mtd_list_t *nextitem;

	while (slram_mtdlist) {
		nextitem = slram_mtdlist->next;
		del_mtd_device(slram_mtdlist->mtdinfo);
		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
		kfree(slram_mtdlist->mtdinfo->priv);
		kfree(slram_mtdlist->mtdinfo);
		kfree(slram_mtdlist);
		slram_mtdlist = nextitem;
	}
}

static unsigned long handle_unit(unsigned long value, char *unit)
{
	if ((*unit == 'M') || (*unit == 'm')) {
		return(value * 1024 * 1024);
	} else if ((*unit == 'K') || (*unit == 'k')) {
		return(value * 1024);
	}
	return(value);
}

static int parse_cmdline(char *devname, char *szstart, char *szlength)
{
	char *buffer;
	unsigned long devstart;
	unsigned long devlength;

	if ((!devname) || (!szstart) || (!szlength)) {
		unregister_devices();
		return(-EINVAL);
	}

	devstart = simple_strtoul(szstart, &buffer, 0);
	devstart = handle_unit(devstart, buffer);

	if (*(szlength) != '+') {
		devlength = simple_strtoul(szlength, &buffer, 0);
		devlength = handle_unit(devlength, buffer) - devstart;
	} else {
		devlength = simple_strtoul(szlength + 1, &buffer, 0);
		devlength = handle_unit(devlength, buffer);
	}
	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
			devname, devstart, devlength);
	if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
		E("slram: Illegal start / length parameter.\n");
		return(-EINVAL);
	}

	if ((devstart = register_device(devname, devstart, devlength))){
		unregister_devices();
		return((int)devstart);
	}
	return(0);
}

#ifndef MODULE

static int __init mtd_slram_setup(char *str)
{
	map = str;
	return(1);
}

__setup("slram=", mtd_slram_setup);

#endif

static int init_slram(void)
{
	char *devname;
	int i;

#ifndef MODULE
	char *devstart;
	char *devlength;

	i = 0;

	if (!map) {
		E("slram: not enough parameters.\n");
		return(-EINVAL);
	}
	while (map) {
		devname = devstart = devlength = NULL;

		if (!(devname = strsep(&map, ","))) {
			E("slram: No devicename specified.\n");
			break;
		}
		T("slram: devname = %s\n", devname);
		if ((!map) || (!(devstart = strsep(&map, ",")))) {
			E("slram: No devicestart specified.\n");
		}
		T("slram: devstart = %s\n", devstart);
		if ((!map) || (!(devlength = strsep(&map, ",")))) {
			E("slram: No devicelength / -end specified.\n");
		}
		T("slram: devlength = %s\n", devlength);
		if (parse_cmdline(devname, devstart, devlength) != 0) {
			return(-EINVAL);
		}
	}
#else
	int count;

	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
			count++) {
	}

	if ((count % 3 != 0) || (count == 0)) {
		E("slram: not enough parameters.\n");
		return(-EINVAL);
	}
	for (i = 0; i < (count / 3); i++) {
		devname = map[i * 3];

		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
			return(-EINVAL);
		}

	}
#endif /* !MODULE */

	return(0);
}

static void __exit cleanup_slram(void)
{
	unregister_devices();
}

module_init(init_slram);
module_exit(cleanup_slram);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
MODULE_DESCRIPTION("MTD driver for uncached system RAM");
OpenPOWER on IntegriCloud