slram.c revision cd354f1ae75e6466a7e31b727faede57a1f89ca5 
1/*======================================================================
2
3  $Id: slram.c,v 1.36 2005/11/07 11:14:25 gleixner 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/ptrace.h>
39#include <linux/slab.h>
40#include <linux/string.h>
41#include <linux/timer.h>
42#include <linux/major.h>
43#include <linux/fs.h>
44#include <linux/ioctl.h>
45#include <linux/init.h>
46#include <asm/io.h>
47#include <asm/system.h>
48
49#include <linux/mtd/mtd.h>
50
51#define SLRAM_MAX_DEVICES_PARAMS 6		/* 3 parameters / device */
52#define SLRAM_BLK_SZ 0x4000
53
54#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
55#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
56
57typedef struct slram_priv {
58	u_char *start;
59	u_char *end;
60} slram_priv_t;
61
62typedef struct slram_mtd_list {
63	struct mtd_info *mtdinfo;
64	struct slram_mtd_list *next;
65} slram_mtd_list_t;
66
67#ifdef MODULE
68static char *map[SLRAM_MAX_DEVICES_PARAMS];
69
70module_param_array(map, charp, NULL, 0);
71MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
72#else
73static char *map;
74#endif
75
76static slram_mtd_list_t *slram_mtdlist = NULL;
77
78static int slram_erase(struct mtd_info *, struct erase_info *);
79static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **);
80static void slram_unpoint(struct mtd_info *, u_char *, loff_t,	size_t);
81static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
82static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
83
84static 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	mtd_erase_callback(instr);
102
103	return(0);
104}
105
106static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
107		size_t *retlen, u_char **mtdbuf)
108{
109	slram_priv_t *priv = mtd->priv;
110
111	if (from + len > mtd->size)
112		return -EINVAL;
113
114	*mtdbuf = priv->start + from;
115	*retlen = len;
116	return(0);
117}
118
119static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
120{
121}
122
123static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
124		size_t *retlen, u_char *buf)
125{
126	slram_priv_t *priv = mtd->priv;
127
128	if (from > mtd->size)
129		return -EINVAL;
130
131	if (from + len > mtd->size)
132		len = mtd->size - from;
133
134	memcpy(buf, priv->start + from, len);
135
136	*retlen = len;
137	return(0);
138}
139
140static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
141		size_t *retlen, const u_char *buf)
142{
143	slram_priv_t *priv = mtd->priv;
144
145	if (to + len > mtd->size)
146		return -EINVAL;
147
148	memcpy(priv->start + to, buf, len);
149
150	*retlen = len;
151	return(0);
152}
153
154/*====================================================================*/
155
156static int register_device(char *name, unsigned long start, unsigned long length)
157{
158	slram_mtd_list_t **curmtd;
159
160	curmtd = &slram_mtdlist;
161	while (*curmtd) {
162		curmtd = &(*curmtd)->next;
163	}
164
165	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
166	if (!(*curmtd)) {
167		E("slram: Cannot allocate new MTD device.\n");
168		return(-ENOMEM);
169	}
170	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
171	(*curmtd)->next = NULL;
172
173	if ((*curmtd)->mtdinfo)	{
174		(*curmtd)->mtdinfo->priv =
175			kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
176
177		if (!(*curmtd)->mtdinfo->priv) {
178			kfree((*curmtd)->mtdinfo);
179			(*curmtd)->mtdinfo = NULL;
180		}
181	}
182
183	if (!(*curmtd)->mtdinfo) {
184		E("slram: Cannot allocate new MTD device.\n");
185		return(-ENOMEM);
186	}
187
188	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
189				ioremap(start, length))) {
190		E("slram: ioremap failed\n");
191		return -EIO;
192	}
193	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
194		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
195
196
197	(*curmtd)->mtdinfo->name = name;
198	(*curmtd)->mtdinfo->size = length;
199	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
200        (*curmtd)->mtdinfo->erase = slram_erase;
201	(*curmtd)->mtdinfo->point = slram_point;
202	(*curmtd)->mtdinfo->unpoint = slram_unpoint;
203	(*curmtd)->mtdinfo->read = slram_read;
204	(*curmtd)->mtdinfo->write = slram_write;
205	(*curmtd)->mtdinfo->owner = THIS_MODULE;
206	(*curmtd)->mtdinfo->type = MTD_RAM;
207	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
208	(*curmtd)->mtdinfo->writesize = 1;
209
210	if (add_mtd_device((*curmtd)->mtdinfo))	{
211		E("slram: Failed to register new device\n");
212		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
213		kfree((*curmtd)->mtdinfo->priv);
214		kfree((*curmtd)->mtdinfo);
215		return(-EAGAIN);
216	}
217	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
218			(start / 1024), ((start + length) / 1024));
219	T("slram: Mapped from 0x%p to 0x%p\n",
220			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
221			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
222	return(0);
223}
224
225static void unregister_devices(void)
226{
227	slram_mtd_list_t *nextitem;
228
229	while (slram_mtdlist) {
230		nextitem = slram_mtdlist->next;
231		del_mtd_device(slram_mtdlist->mtdinfo);
232		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
233		kfree(slram_mtdlist->mtdinfo->priv);
234		kfree(slram_mtdlist->mtdinfo);
235		kfree(slram_mtdlist);
236		slram_mtdlist = nextitem;
237	}
238}
239
240static unsigned long handle_unit(unsigned long value, char *unit)
241{
242	if ((*unit == 'M') || (*unit == 'm')) {
243		return(value * 1024 * 1024);
244	} else if ((*unit == 'K') || (*unit == 'k')) {
245		return(value * 1024);
246	}
247	return(value);
248}
249
250static int parse_cmdline(char *devname, char *szstart, char *szlength)
251{
252	char *buffer;
253	unsigned long devstart;
254	unsigned long devlength;
255
256	if ((!devname) || (!szstart) || (!szlength)) {
257		unregister_devices();
258		return(-EINVAL);
259	}
260
261	devstart = simple_strtoul(szstart, &buffer, 0);
262	devstart = handle_unit(devstart, buffer);
263
264	if (*(szlength) != '+') {
265		devlength = simple_strtoul(szlength, &buffer, 0);
266		devlength = handle_unit(devlength, buffer) - devstart;
267	} else {
268		devlength = simple_strtoul(szlength + 1, &buffer, 0);
269		devlength = handle_unit(devlength, buffer);
270	}
271	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
272			devname, devstart, devlength);
273	if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
274		E("slram: Illegal start / length parameter.\n");
275		return(-EINVAL);
276	}
277
278	if ((devstart = register_device(devname, devstart, devlength))){
279		unregister_devices();
280		return((int)devstart);
281	}
282	return(0);
283}
284
285#ifndef MODULE
286
287static int __init mtd_slram_setup(char *str)
288{
289	map = str;
290	return(1);
291}
292
293__setup("slram=", mtd_slram_setup);
294
295#endif
296
297static int init_slram(void)
298{
299	char *devname;
300	int i;
301
302#ifndef MODULE
303	char *devstart;
304	char *devlength;
305
306	i = 0;
307
308	if (!map) {
309		E("slram: not enough parameters.\n");
310		return(-EINVAL);
311	}
312	while (map) {
313		devname = devstart = devlength = NULL;
314
315		if (!(devname = strsep(&map, ","))) {
316			E("slram: No devicename specified.\n");
317			break;
318		}
319		T("slram: devname = %s\n", devname);
320		if ((!map) || (!(devstart = strsep(&map, ",")))) {
321			E("slram: No devicestart specified.\n");
322		}
323		T("slram: devstart = %s\n", devstart);
324		if ((!map) || (!(devlength = strsep(&map, ",")))) {
325			E("slram: No devicelength / -end specified.\n");
326		}
327		T("slram: devlength = %s\n", devlength);
328		if (parse_cmdline(devname, devstart, devlength) != 0) {
329			return(-EINVAL);
330		}
331	}
332#else
333	int count;
334
335	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
336			count++) {
337	}
338
339	if ((count % 3 != 0) || (count == 0)) {
340		E("slram: not enough parameters.\n");
341		return(-EINVAL);
342	}
343	for (i = 0; i < (count / 3); i++) {
344		devname = map[i * 3];
345
346		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
347			return(-EINVAL);
348		}
349
350	}
351#endif /* !MODULE */
352
353	return(0);
354}
355
356static void __exit cleanup_slram(void)
357{
358	unregister_devices();
359}
360
361module_init(init_slram);
362module_exit(cleanup_slram);
363
364MODULE_LICENSE("GPL");
365MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
366MODULE_DESCRIPTION("MTD driver for uncached system RAM");
367