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 contiguous memory region. Therefore
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 
55 typedef struct slram_priv {
56 	u_char *start;
57 	u_char *end;
58 } slram_priv_t;
59 
60 typedef struct slram_mtd_list {
61 	struct mtd_info *mtdinfo;
62 	struct slram_mtd_list *next;
63 } slram_mtd_list_t;
64 
65 #ifdef MODULE
66 static char *map[SLRAM_MAX_DEVICES_PARAMS];
67 
68 module_param_array(map, charp, NULL, 0);
69 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
70 #else
71 static char *map;
72 #endif
73 
74 static slram_mtd_list_t *slram_mtdlist = NULL;
75 
76 static int slram_erase(struct mtd_info *, struct erase_info *);
77 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
78 		resource_size_t *);
79 static void slram_unpoint(struct mtd_info *, loff_t, size_t);
80 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
81 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
82 
slram_erase(struct mtd_info * mtd,struct erase_info * instr)83 static 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 
slram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,void ** virt,resource_size_t * phys)105 static 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 
slram_unpoint(struct mtd_info * mtd,loff_t from,size_t len)122 static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
123 {
124 }
125 
slram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)126 static 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 
slram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)143 static 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 
register_device(char * name,unsigned long start,unsigned long length)159 static 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 
unregister_devices(void)228 static 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 
handle_unit(unsigned long value,char * unit)243 static 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 
parse_cmdline(char * devname,char * szstart,char * szlength)253 static 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 
289 err_out:
290 	E("slram: Illegal length parameter.\n");
291 	return(-EINVAL);
292 }
293 
294 #ifndef MODULE
295 
mtd_slram_setup(char * str)296 static 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 
init_slram(void)306 static int __init 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; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
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 
cleanup_slram(void)365 static void __exit cleanup_slram(void)
366 {
367 	unregister_devices();
368 }
369 
370 module_init(init_slram);
371 module_exit(cleanup_slram);
372 
373 MODULE_LICENSE("GPL");
374 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
375 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
376