slram.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
1/*======================================================================
2
3  $Id: slram.c,v 1.33 2005/01/05 18:05:13 dwmw2 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
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	*mtdbuf = priv->start + from;
112	*retlen = len;
113	return(0);
114}
115
116static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
117{
118}
119
120static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
121		size_t *retlen, u_char *buf)
122{
123	slram_priv_t *priv = mtd->priv;
124
125	memcpy(buf, priv->start + from, len);
126
127	*retlen = len;
128	return(0);
129}
130
131static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
132		size_t *retlen, const u_char *buf)
133{
134	slram_priv_t *priv = mtd->priv;
135
136	memcpy(priv->start + to, buf, len);
137
138	*retlen = len;
139	return(0);
140}
141
142/*====================================================================*/
143
144static int register_device(char *name, unsigned long start, unsigned long length)
145{
146	slram_mtd_list_t **curmtd;
147
148	curmtd = &slram_mtdlist;
149	while (*curmtd) {
150		curmtd = &(*curmtd)->next;
151	}
152
153	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
154	if (!(*curmtd)) {
155		E("slram: Cannot allocate new MTD device.\n");
156		return(-ENOMEM);
157	}
158	(*curmtd)->mtdinfo = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
159	(*curmtd)->next = NULL;
160
161	if ((*curmtd)->mtdinfo)	{
162		memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));
163		(*curmtd)->mtdinfo->priv =
164			kmalloc(sizeof(slram_priv_t), GFP_KERNEL);
165
166		if (!(*curmtd)->mtdinfo->priv) {
167			kfree((*curmtd)->mtdinfo);
168			(*curmtd)->mtdinfo = NULL;
169		} else {
170			memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));
171		}
172	}
173
174	if (!(*curmtd)->mtdinfo) {
175		E("slram: Cannot allocate new MTD device.\n");
176		return(-ENOMEM);
177	}
178
179	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
180				ioremap(start, length))) {
181		E("slram: ioremap failed\n");
182		return -EIO;
183	}
184	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
185		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
186
187
188	(*curmtd)->mtdinfo->name = name;
189	(*curmtd)->mtdinfo->size = length;
190	(*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS |
191					MTD_WRITEB_WRITEABLE | MTD_VOLATILE;
192        (*curmtd)->mtdinfo->erase = slram_erase;
193	(*curmtd)->mtdinfo->point = slram_point;
194	(*curmtd)->mtdinfo->unpoint = slram_unpoint;
195	(*curmtd)->mtdinfo->read = slram_read;
196	(*curmtd)->mtdinfo->write = slram_write;
197	(*curmtd)->mtdinfo->owner = THIS_MODULE;
198	(*curmtd)->mtdinfo->type = MTD_RAM;
199	(*curmtd)->mtdinfo->erasesize = 0x0;
200
201	if (add_mtd_device((*curmtd)->mtdinfo))	{
202		E("slram: Failed to register new device\n");
203		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
204		kfree((*curmtd)->mtdinfo->priv);
205		kfree((*curmtd)->mtdinfo);
206		return(-EAGAIN);
207	}
208	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
209			(start / 1024), ((start + length) / 1024));
210	T("slram: Mapped from 0x%p to 0x%p\n",
211			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
212			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
213	return(0);
214}
215
216static void unregister_devices(void)
217{
218	slram_mtd_list_t *nextitem;
219
220	while (slram_mtdlist) {
221		nextitem = slram_mtdlist->next;
222		del_mtd_device(slram_mtdlist->mtdinfo);
223		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
224		kfree(slram_mtdlist->mtdinfo->priv);
225		kfree(slram_mtdlist->mtdinfo);
226		kfree(slram_mtdlist);
227		slram_mtdlist = nextitem;
228	}
229}
230
231static unsigned long handle_unit(unsigned long value, char *unit)
232{
233	if ((*unit == 'M') || (*unit == 'm')) {
234		return(value * 1024 * 1024);
235	} else if ((*unit == 'K') || (*unit == 'k')) {
236		return(value * 1024);
237	}
238	return(value);
239}
240
241static int parse_cmdline(char *devname, char *szstart, char *szlength)
242{
243	char *buffer;
244	unsigned long devstart;
245	unsigned long devlength;
246
247	if ((!devname) || (!szstart) || (!szlength)) {
248		unregister_devices();
249		return(-EINVAL);
250	}
251
252	devstart = simple_strtoul(szstart, &buffer, 0);
253	devstart = handle_unit(devstart, buffer);
254
255	if (*(szlength) != '+') {
256		devlength = simple_strtoul(szlength, &buffer, 0);
257		devlength = handle_unit(devlength, buffer) - devstart;
258	} else {
259		devlength = simple_strtoul(szlength + 1, &buffer, 0);
260		devlength = handle_unit(devlength, buffer);
261	}
262	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
263			devname, devstart, devlength);
264	if ((devstart < 0) || (devlength < 0)) {
265		E("slram: Illegal start / length parameter.\n");
266		return(-EINVAL);
267	}
268
269	if ((devstart = register_device(devname, devstart, devlength))){
270		unregister_devices();
271		return((int)devstart);
272	}
273	return(0);
274}
275
276#ifndef MODULE
277
278static int __init mtd_slram_setup(char *str)
279{
280	map = str;
281	return(1);
282}
283
284__setup("slram=", mtd_slram_setup);
285
286#endif
287
288static int init_slram(void)
289{
290	char *devname;
291	int i;
292
293#ifndef MODULE
294	char *devstart;
295	char *devlength;
296
297	i = 0;
298
299	if (!map) {
300		E("slram: not enough parameters.\n");
301		return(-EINVAL);
302	}
303	while (map) {
304		devname = devstart = devlength = NULL;
305
306		if (!(devname = strsep(&map, ","))) {
307			E("slram: No devicename specified.\n");
308			break;
309		}
310		T("slram: devname = %s\n", devname);
311		if ((!map) || (!(devstart = strsep(&map, ",")))) {
312			E("slram: No devicestart specified.\n");
313		}
314		T("slram: devstart = %s\n", devstart);
315		if ((!map) || (!(devlength = strsep(&map, ",")))) {
316			E("slram: No devicelength / -end specified.\n");
317		}
318		T("slram: devlength = %s\n", devlength);
319		if (parse_cmdline(devname, devstart, devlength) != 0) {
320			return(-EINVAL);
321		}
322	}
323#else
324	int count;
325
326	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
327			count++) {
328	}
329
330	if ((count % 3 != 0) || (count == 0)) {
331		E("slram: not enough parameters.\n");
332		return(-EINVAL);
333	}
334	for (i = 0; i < (count / 3); i++) {
335		devname = map[i * 3];
336
337		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
338			return(-EINVAL);
339		}
340
341	}
342#endif /* !MODULE */
343
344	return(0);
345}
346
347static void __exit cleanup_slram(void)
348{
349	unregister_devices();
350}
351
352module_init(init_slram);
353module_exit(cleanup_slram);
354
355MODULE_LICENSE("GPL");
356MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
357MODULE_DESCRIPTION("MTD driver for uncached system RAM");
358