slram.c revision 3afd522de8d8ec446efe957b86e4f63e3dd8ce9d 
1/*======================================================================
2
3  This driver provides a method to access memory not used by the kernel
4  itself (i.e. if the kernel commandline mem=xxx is used). To actually
5  use slram at least mtdblock or mtdchar is required (for block or
6  character device access).
7
8  Usage:
9
10  if compiled as loadable module:
11    modprobe slram map=<name>,<start>,<end/offset>
12  if statically linked into the kernel use the following kernel cmd.line
13    slram=<name>,<start>,<end/offset>
14
15  <name>: name of the device that will be listed in /proc/mtd
16  <start>: start of the memory region, decimal or hex (0xabcdef)
17  <end/offset>: end of the memory region. It's possible to use +0x1234
18                to specify the offset instead of the absolute address
19
20  NOTE:
21  With slram it's only possible to map a contigous memory region. Therfore
22  if there's a device mapped somewhere in the region specified slram will
23  fail to load (see kernel log if modprobe fails).
24
25  -
26
27  Jochen Schaeuble <psionic@psionic.de>
28
29======================================================================*/
30
31
32#include <linux/module.h>
33#include <asm/uaccess.h>
34#include <linux/types.h>
35#include <linux/kernel.h>
36#include <linux/ptrace.h>
37#include <linux/slab.h>
38#include <linux/string.h>
39#include <linux/timer.h>
40#include <linux/major.h>
41#include <linux/fs.h>
42#include <linux/ioctl.h>
43#include <linux/init.h>
44#include <asm/io.h>
45#include <asm/system.h>
46
47#include <linux/mtd/mtd.h>
48
49#define SLRAM_MAX_DEVICES_PARAMS 6		/* 3 parameters / device */
50#define SLRAM_BLK_SZ 0x4000
51
52#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
53#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
54
55typedef struct slram_priv {
56	u_char *start;
57	u_char *end;
58} slram_priv_t;
59
60typedef struct slram_mtd_list {
61	struct mtd_info *mtdinfo;
62	struct slram_mtd_list *next;
63} slram_mtd_list_t;
64
65#ifdef MODULE
66static char *map[SLRAM_MAX_DEVICES_PARAMS];
67
68module_param_array(map, charp, NULL, 0);
69MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
70#else
71static char *map;
72#endif
73
74static slram_mtd_list_t *slram_mtdlist = NULL;
75
76static int slram_erase(struct mtd_info *, struct erase_info *);
77static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
78		resource_size_t *);
79static void slram_unpoint(struct mtd_info *, loff_t, size_t);
80static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
81static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
82
83static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
84{
85	slram_priv_t *priv = mtd->priv;
86
87	if (instr->addr + instr->len > mtd->size) {
88		return(-EINVAL);
89	}
90
91	memset(priv->start + instr->addr, 0xff, instr->len);
92
93	/* This'll catch a few races. Free the thing before returning :)
94	 * I don't feel at all ashamed. This kind of thing is possible anyway
95	 * with flash, but unlikely.
96	 */
97
98	instr->state = MTD_ERASE_DONE;
99
100	mtd_erase_callback(instr);
101
102	return(0);
103}
104
105static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
106		size_t *retlen, void **virt, resource_size_t *phys)
107{
108	slram_priv_t *priv = mtd->priv;
109
110	/* can we return a physical address with this driver? */
111	if (phys)
112		return -EINVAL;
113
114	if (from + len > mtd->size)
115		return -EINVAL;
116
117	*virt = priv->start + from;
118	*retlen = len;
119	return(0);
120}
121
122static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
123{
124}
125
126static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
127		size_t *retlen, u_char *buf)
128{
129	slram_priv_t *priv = mtd->priv;
130
131	if (from > mtd->size)
132		return -EINVAL;
133
134	if (from + len > mtd->size)
135		len = mtd->size - from;
136
137	memcpy(buf, priv->start + from, len);
138
139	*retlen = len;
140	return(0);
141}
142
143static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
144		size_t *retlen, const u_char *buf)
145{
146	slram_priv_t *priv = mtd->priv;
147
148	if (to + len > mtd->size)
149		return -EINVAL;
150
151	memcpy(priv->start + to, buf, len);
152
153	*retlen = len;
154	return(0);
155}
156
157/*====================================================================*/
158
159static int register_device(char *name, unsigned long start, unsigned long length)
160{
161	slram_mtd_list_t **curmtd;
162
163	curmtd = &slram_mtdlist;
164	while (*curmtd) {
165		curmtd = &(*curmtd)->next;
166	}
167
168	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
169	if (!(*curmtd)) {
170		E("slram: Cannot allocate new MTD device.\n");
171		return(-ENOMEM);
172	}
173	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
174	(*curmtd)->next = NULL;
175
176	if ((*curmtd)->mtdinfo)	{
177		(*curmtd)->mtdinfo->priv =
178			kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
179
180		if (!(*curmtd)->mtdinfo->priv) {
181			kfree((*curmtd)->mtdinfo);
182			(*curmtd)->mtdinfo = NULL;
183		}
184	}
185
186	if (!(*curmtd)->mtdinfo) {
187		E("slram: Cannot allocate new MTD device.\n");
188		return(-ENOMEM);
189	}
190
191	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
192				ioremap(start, length))) {
193		E("slram: ioremap failed\n");
194		return -EIO;
195	}
196	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
197		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
198
199
200	(*curmtd)->mtdinfo->name = name;
201	(*curmtd)->mtdinfo->size = length;
202	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
203        (*curmtd)->mtdinfo->erase = slram_erase;
204	(*curmtd)->mtdinfo->point = slram_point;
205	(*curmtd)->mtdinfo->unpoint = slram_unpoint;
206	(*curmtd)->mtdinfo->read = slram_read;
207	(*curmtd)->mtdinfo->write = slram_write;
208	(*curmtd)->mtdinfo->owner = THIS_MODULE;
209	(*curmtd)->mtdinfo->type = MTD_RAM;
210	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
211	(*curmtd)->mtdinfo->writesize = 1;
212
213	if (add_mtd_device((*curmtd)->mtdinfo))	{
214		E("slram: Failed to register new device\n");
215		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
216		kfree((*curmtd)->mtdinfo->priv);
217		kfree((*curmtd)->mtdinfo);
218		return(-EAGAIN);
219	}
220	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
221			(start / 1024), ((start + length) / 1024));
222	T("slram: Mapped from 0x%p to 0x%p\n",
223			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
224			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
225	return(0);
226}
227
228static void unregister_devices(void)
229{
230	slram_mtd_list_t *nextitem;
231
232	while (slram_mtdlist) {
233		nextitem = slram_mtdlist->next;
234		del_mtd_device(slram_mtdlist->mtdinfo);
235		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
236		kfree(slram_mtdlist->mtdinfo->priv);
237		kfree(slram_mtdlist->mtdinfo);
238		kfree(slram_mtdlist);
239		slram_mtdlist = nextitem;
240	}
241}
242
243static unsigned long handle_unit(unsigned long value, char *unit)
244{
245	if ((*unit == 'M') || (*unit == 'm')) {
246		return(value * 1024 * 1024);
247	} else if ((*unit == 'K') || (*unit == 'k')) {
248		return(value * 1024);
249	}
250	return(value);
251}
252
253static int parse_cmdline(char *devname, char *szstart, char *szlength)
254{
255	char *buffer;
256	unsigned long devstart;
257	unsigned long devlength;
258
259	if ((!devname) || (!szstart) || (!szlength)) {
260		unregister_devices();
261		return(-EINVAL);
262	}
263
264	devstart = simple_strtoul(szstart, &buffer, 0);
265	devstart = handle_unit(devstart, buffer);
266
267	if (*(szlength) != '+') {
268		devlength = simple_strtoul(szlength, &buffer, 0);
269		devlength = handle_unit(devlength, buffer) - devstart;
270		if (devlength < devstart)
271			goto err_out;
272
273		devlength -= devstart;
274	} else {
275		devlength = simple_strtoul(szlength + 1, &buffer, 0);
276		devlength = handle_unit(devlength, buffer);
277	}
278	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
279			devname, devstart, devlength);
280	if (devlength % SLRAM_BLK_SZ != 0)
281		goto err_out;
282
283	if ((devstart = register_device(devname, devstart, devlength))){
284		unregister_devices();
285		return((int)devstart);
286	}
287	return(0);
288
289err_out:
290	E("slram: Illegal length parameter.\n");
291	return(-EINVAL);
292}
293
294#ifndef MODULE
295
296static int __init mtd_slram_setup(char *str)
297{
298	map = str;
299	return(1);
300}
301
302__setup("slram=", mtd_slram_setup);
303
304#endif
305
306static int init_slram(void)
307{
308	char *devname;
309	int i;
310
311#ifndef MODULE
312	char *devstart;
313	char *devlength;
314
315	i = 0;
316
317	if (!map) {
318		E("slram: not enough parameters.\n");
319		return(-EINVAL);
320	}
321	while (map) {
322		devname = devstart = devlength = NULL;
323
324		if (!(devname = strsep(&map, ","))) {
325			E("slram: No devicename specified.\n");
326			break;
327		}
328		T("slram: devname = %s\n", devname);
329		if ((!map) || (!(devstart = strsep(&map, ",")))) {
330			E("slram: No devicestart specified.\n");
331		}
332		T("slram: devstart = %s\n", devstart);
333		if ((!map) || (!(devlength = strsep(&map, ",")))) {
334			E("slram: No devicelength / -end specified.\n");
335		}
336		T("slram: devlength = %s\n", devlength);
337		if (parse_cmdline(devname, devstart, devlength) != 0) {
338			return(-EINVAL);
339		}
340	}
341#else
342	int count;
343
344	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
345			count++) {
346	}
347
348	if ((count % 3 != 0) || (count == 0)) {
349		E("slram: not enough parameters.\n");
350		return(-EINVAL);
351	}
352	for (i = 0; i < (count / 3); i++) {
353		devname = map[i * 3];
354
355		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
356			return(-EINVAL);
357		}
358
359	}
360#endif /* !MODULE */
361
362	return(0);
363}
364
365static void __exit cleanup_slram(void)
366{
367	unregister_devices();
368}
369
370module_init(init_slram);
371module_exit(cleanup_slram);
372
373MODULE_LICENSE("GPL");
374MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
375MODULE_DESCRIPTION("MTD driver for uncached system RAM");
376