slram.c revision e5580fbe8a950131b9ccccce0f962811dfb9ef43 
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/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#define SLRAM_BLK_SZ 0x4000
54
55#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
56#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
57
58typedef struct slram_priv {
59	u_char *start;
60	u_char *end;
61} slram_priv_t;
62
63typedef struct slram_mtd_list {
64	struct mtd_info *mtdinfo;
65	struct slram_mtd_list *next;
66} slram_mtd_list_t;
67
68#ifdef MODULE
69static char *map[SLRAM_MAX_DEVICES_PARAMS];
70
71module_param_array(map, charp, NULL, 0);
72MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
73#else
74static char *map;
75#endif
76
77static slram_mtd_list_t *slram_mtdlist = NULL;
78
79static int slram_erase(struct mtd_info *, struct erase_info *);
80static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **);
81static void slram_unpoint(struct mtd_info *, u_char *, loff_t,	size_t);
82static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
83static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
84
85static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
86{
87	slram_priv_t *priv = mtd->priv;
88
89	if (instr->addr + instr->len > mtd->size) {
90		return(-EINVAL);
91	}
92
93	memset(priv->start + instr->addr, 0xff, instr->len);
94
95	/* This'll catch a few races. Free the thing before returning :)
96	 * I don't feel at all ashamed. This kind of thing is possible anyway
97	 * with flash, but unlikely.
98	 */
99
100	instr->state = MTD_ERASE_DONE;
101
102	mtd_erase_callback(instr);
103
104	return(0);
105}
106
107static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
108		size_t *retlen, u_char **mtdbuf)
109{
110	slram_priv_t *priv = mtd->priv;
111
112	if (from + len > mtd->size)
113		return -EINVAL;
114
115	*mtdbuf = priv->start + from;
116	*retlen = len;
117	return(0);
118}
119
120static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
121{
122}
123
124static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
125		size_t *retlen, u_char *buf)
126{
127	slram_priv_t *priv = mtd->priv;
128
129	if (from > mtd->size)
130		return -EINVAL;
131
132	if (from + len > mtd->size)
133		len = mtd->size - from;
134
135	memcpy(buf, priv->start + from, len);
136
137	*retlen = len;
138	return(0);
139}
140
141static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
142		size_t *retlen, const u_char *buf)
143{
144	slram_priv_t *priv = mtd->priv;
145
146	if (to + len > mtd->size)
147		return -EINVAL;
148
149	memcpy(priv->start + to, buf, len);
150
151	*retlen = len;
152	return(0);
153}
154
155/*====================================================================*/
156
157static int register_device(char *name, unsigned long start, unsigned long length)
158{
159	slram_mtd_list_t **curmtd;
160
161	curmtd = &slram_mtdlist;
162	while (*curmtd) {
163		curmtd = &(*curmtd)->next;
164	}
165
166	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
167	if (!(*curmtd)) {
168		E("slram: Cannot allocate new MTD device.\n");
169		return(-ENOMEM);
170	}
171	(*curmtd)->mtdinfo = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
172	(*curmtd)->next = NULL;
173
174	if ((*curmtd)->mtdinfo)	{
175		memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));
176		(*curmtd)->mtdinfo->priv =
177			kmalloc(sizeof(slram_priv_t), GFP_KERNEL);
178
179		if (!(*curmtd)->mtdinfo->priv) {
180			kfree((*curmtd)->mtdinfo);
181			(*curmtd)->mtdinfo = NULL;
182		} else {
183			memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));
184		}
185	}
186
187	if (!(*curmtd)->mtdinfo) {
188		E("slram: Cannot allocate new MTD device.\n");
189		return(-ENOMEM);
190	}
191
192	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
193				ioremap(start, length))) {
194		E("slram: ioremap failed\n");
195		return -EIO;
196	}
197	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
198		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
199
200
201	(*curmtd)->mtdinfo->name = name;
202	(*curmtd)->mtdinfo->size = length;
203	(*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS |
204					MTD_WRITEB_WRITEABLE | MTD_VOLATILE | MTD_CAP_RAM;
205        (*curmtd)->mtdinfo->erase = slram_erase;
206	(*curmtd)->mtdinfo->point = slram_point;
207	(*curmtd)->mtdinfo->unpoint = slram_unpoint;
208	(*curmtd)->mtdinfo->read = slram_read;
209	(*curmtd)->mtdinfo->write = slram_write;
210	(*curmtd)->mtdinfo->owner = THIS_MODULE;
211	(*curmtd)->mtdinfo->type = MTD_RAM;
212	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
213
214	if (add_mtd_device((*curmtd)->mtdinfo))	{
215		E("slram: Failed to register new device\n");
216		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
217		kfree((*curmtd)->mtdinfo->priv);
218		kfree((*curmtd)->mtdinfo);
219		return(-EAGAIN);
220	}
221	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
222			(start / 1024), ((start + length) / 1024));
223	T("slram: Mapped from 0x%p to 0x%p\n",
224			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
225			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
226	return(0);
227}
228
229static void unregister_devices(void)
230{
231	slram_mtd_list_t *nextitem;
232
233	while (slram_mtdlist) {
234		nextitem = slram_mtdlist->next;
235		del_mtd_device(slram_mtdlist->mtdinfo);
236		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
237		kfree(slram_mtdlist->mtdinfo->priv);
238		kfree(slram_mtdlist->mtdinfo);
239		kfree(slram_mtdlist);
240		slram_mtdlist = nextitem;
241	}
242}
243
244static unsigned long handle_unit(unsigned long value, char *unit)
245{
246	if ((*unit == 'M') || (*unit == 'm')) {
247		return(value * 1024 * 1024);
248	} else if ((*unit == 'K') || (*unit == 'k')) {
249		return(value * 1024);
250	}
251	return(value);
252}
253
254static int parse_cmdline(char *devname, char *szstart, char *szlength)
255{
256	char *buffer;
257	unsigned long devstart;
258	unsigned long devlength;
259
260	if ((!devname) || (!szstart) || (!szlength)) {
261		unregister_devices();
262		return(-EINVAL);
263	}
264
265	devstart = simple_strtoul(szstart, &buffer, 0);
266	devstart = handle_unit(devstart, buffer);
267
268	if (*(szlength) != '+') {
269		devlength = simple_strtoul(szlength, &buffer, 0);
270		devlength = handle_unit(devlength, buffer) - devstart;
271	} else {
272		devlength = simple_strtoul(szlength + 1, &buffer, 0);
273		devlength = handle_unit(devlength, buffer);
274	}
275	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
276			devname, devstart, devlength);
277	if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
278		E("slram: Illegal start / length parameter.\n");
279		return(-EINVAL);
280	}
281
282	if ((devstart = register_device(devname, devstart, devlength))){
283		unregister_devices();
284		return((int)devstart);
285	}
286	return(0);
287}
288
289#ifndef MODULE
290
291static int __init mtd_slram_setup(char *str)
292{
293	map = str;
294	return(1);
295}
296
297__setup("slram=", mtd_slram_setup);
298
299#endif
300
301static int init_slram(void)
302{
303	char *devname;
304	int i;
305
306#ifndef MODULE
307	char *devstart;
308	char *devlength;
309
310	i = 0;
311
312	if (!map) {
313		E("slram: not enough parameters.\n");
314		return(-EINVAL);
315	}
316	while (map) {
317		devname = devstart = devlength = NULL;
318
319		if (!(devname = strsep(&map, ","))) {
320			E("slram: No devicename specified.\n");
321			break;
322		}
323		T("slram: devname = %s\n", devname);
324		if ((!map) || (!(devstart = strsep(&map, ",")))) {
325			E("slram: No devicestart specified.\n");
326		}
327		T("slram: devstart = %s\n", devstart);
328		if ((!map) || (!(devlength = strsep(&map, ",")))) {
329			E("slram: No devicelength / -end specified.\n");
330		}
331		T("slram: devlength = %s\n", devlength);
332		if (parse_cmdline(devname, devstart, devlength) != 0) {
333			return(-EINVAL);
334		}
335	}
336#else
337	int count;
338
339	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
340			count++) {
341	}
342
343	if ((count % 3 != 0) || (count == 0)) {
344		E("slram: not enough parameters.\n");
345		return(-EINVAL);
346	}
347	for (i = 0; i < (count / 3); i++) {
348		devname = map[i * 3];
349
350		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
351			return(-EINVAL);
352		}
353
354	}
355#endif /* !MODULE */
356
357	return(0);
358}
359
360static void __exit cleanup_slram(void)
361{
362	unregister_devices();
363}
364
365module_init(init_slram);
366module_exit(cleanup_slram);
367
368MODULE_LICENSE("GPL");
369MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
370MODULE_DESCRIPTION("MTD driver for uncached system RAM");
371