summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/devices/phram.c
blob: 8b66e52ca3ccb811e818dce496ca6e0fcc7c9ecb (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
/**
 * Copyright (c) ????		Jochen Schäuble <psionic@psionic.de>
 * Copyright (c) 2003-2004	Joern Engel <joern@wh.fh-wedel.de>
 *
 * Usage:
 *
 * one commend line parameter per device, each in the form:
 *   phram=<name>,<start>,<len>
 * <name> may be up to 63 characters.
 * <start> and <len> can be octal, decimal or hexadecimal.  If followed
 * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
 * gigabytes.
 *
 * Example:
 *	phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/io.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>

struct phram_mtd_list {
	struct mtd_info mtd;
	struct list_head list;
};

static LIST_HEAD(phram_list);

static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	u_char *start = mtd->priv;

	memset(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 phram_point(struct mtd_info *mtd, loff_t from, size_t len,
		size_t *retlen, void **virt, resource_size_t *phys)
{
	*virt = mtd->priv + from;
	*retlen = len;
	return 0;
}

static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
	return 0;
}

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

	memcpy(buf, start + from, len);
	*retlen = len;
	return 0;
}

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

	memcpy(start + to, buf, len);
	*retlen = len;
	return 0;
}

static void unregister_devices(void)
{
	struct phram_mtd_list *this, *safe;

	list_for_each_entry_safe(this, safe, &phram_list, list) {
		mtd_device_unregister(&this->mtd);
		iounmap(this->mtd.priv);
		kfree(this->mtd.name);
		kfree(this);
	}
}

static int register_device(char *name, phys_addr_t start, size_t len)
{
	struct phram_mtd_list *new;
	int ret = -ENOMEM;

	new = kzalloc(sizeof(*new), GFP_KERNEL);
	if (!new)
		goto out0;

	ret = -EIO;
	new->mtd.priv = ioremap(start, len);
	if (!new->mtd.priv) {
		pr_err("ioremap failed\n");
		goto out1;
	}


	new->mtd.name = name;
	new->mtd.size = len;
	new->mtd.flags = MTD_CAP_RAM;
	new->mtd._erase = phram_erase;
	new->mtd._point = phram_point;
	new->mtd._unpoint = phram_unpoint;
	new->mtd._read = phram_read;
	new->mtd._write = phram_write;
	new->mtd.owner = THIS_MODULE;
	new->mtd.type = MTD_RAM;
	new->mtd.erasesize = PAGE_SIZE;
	new->mtd.writesize = 1;

	ret = -EAGAIN;
	if (mtd_device_register(&new->mtd, NULL, 0)) {
		pr_err("Failed to register new device\n");
		goto out2;
	}

	list_add_tail(&new->list, &phram_list);
	return 0;

out2:
	iounmap(new->mtd.priv);
out1:
	kfree(new);
out0:
	return ret;
}

static int parse_num64(uint64_t *num64, char *token)
{
	size_t len;
	int shift = 0;
	int ret;

	len = strlen(token);
	/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
	if (len > 2) {
		if (token[len - 1] == 'i') {
			switch (token[len - 2]) {
			case 'G':
				shift += 10;
			case 'M':
				shift += 10;
			case 'k':
				shift += 10;
				token[len - 2] = 0;
				break;
			default:
				return -EINVAL;
			}
		}
	}

	ret = kstrtou64(token, 0, num64);
	*num64 <<= shift;

	return ret;
}

static int parse_name(char **pname, const char *token)
{
	size_t len;
	char *name;

	len = strlen(token) + 1;
	if (len > 64)
		return -ENOSPC;

	name = kstrdup(token, GFP_KERNEL);
	if (!name)
		return -ENOMEM;

	*pname = name;
	return 0;
}


static inline void kill_final_newline(char *str)
{
	char *newline = strrchr(str, '\n');

	if (newline && !newline[1])
		*newline = 0;
}


#define parse_err(fmt, args...) do {	\
	pr_err(fmt , ## args);	\
	return 1;		\
} while (0)

#ifndef MODULE
static int phram_init_called;
/*
 * This shall contain the module parameter if any. It is of the form:
 * - phram=<device>,<address>,<size> for module case
 * - phram.phram=<device>,<address>,<size> for built-in case
 * We leave 64 bytes for the device name, 20 for the address and 20 for the
 * size.
 * Example: phram.phram=rootfs,0xa0000000,512Mi
 */
static char phram_paramline[64 + 20 + 20];
#endif

static int phram_setup(const char *val)
{
	char buf[64 + 20 + 20], *str = buf;
	char *token[3];
	char *name;
	uint64_t start;
	uint64_t len;
	int i, ret;

	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
		parse_err("parameter too long\n");

	strcpy(str, val);
	kill_final_newline(str);

	for (i = 0; i < 3; i++)
		token[i] = strsep(&str, ",");

	if (str)
		parse_err("too many arguments\n");

	if (!token[2])
		parse_err("not enough arguments\n");

	ret = parse_name(&name, token[0]);
	if (ret)
		return ret;

	ret = parse_num64(&start, token[1]);
	if (ret) {
		kfree(name);
		parse_err("illegal start address\n");
	}

	ret = parse_num64(&len, token[2]);
	if (ret) {
		kfree(name);
		parse_err("illegal device length\n");
	}

	ret = register_device(name, start, len);
	if (!ret)
		pr_info("%s device: %#llx at %#llx\n", name, len, start);
	else
		kfree(name);

	return ret;
}

static int phram_param_call(const char *val, struct kernel_param *kp)
{
#ifdef MODULE
	return phram_setup(val);
#else
	/*
	 * If more parameters are later passed in via
	 * /sys/module/phram/parameters/phram
	 * and init_phram() has already been called,
	 * we can parse the argument now.
	 */

	if (phram_init_called)
		return phram_setup(val);

	/*
	 * During early boot stage, we only save the parameters
	 * here. We must parse them later: if the param passed
	 * from kernel boot command line, phram_param_call() is
	 * called so early that it is not possible to resolve
	 * the device (even kmalloc() fails). Defer that work to
	 * phram_setup().
	 */

	if (strlen(val) >= sizeof(phram_paramline))
		return -ENOSPC;
	strcpy(phram_paramline, val);

	return 0;
#endif
}

module_param_call(phram, phram_param_call, NULL, NULL, 000);
MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");


static int __init init_phram(void)
{
	int ret = 0;

#ifndef MODULE
	if (phram_paramline[0])
		ret = phram_setup(phram_paramline);
	phram_init_called = 1;
#endif

	return ret;
}

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

module_init(init_phram);
module_exit(cleanup_phram);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
MODULE_DESCRIPTION("MTD driver for physical RAM");