xref: /openbmc/linux/drivers/mtd/devices/slram.c (revision 545e4006) 
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 
57 typedef struct slram_priv {
58 	u_char *start;
59 	u_char *end;
60 } slram_priv_t;
61 
62 typedef struct slram_mtd_list {
63 	struct mtd_info *mtdinfo;
64 	struct slram_mtd_list *next;
65 } slram_mtd_list_t;
66 
67 #ifdef MODULE
68 static char *map[SLRAM_MAX_DEVICES_PARAMS];
69 
70 module_param_array(map, charp, NULL, 0);
71 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
72 #else
73 static char *map;
74 #endif
75 
76 static slram_mtd_list_t *slram_mtdlist = NULL;
77 
78 static int slram_erase(struct mtd_info *, struct erase_info *);
79 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
80 		resource_size_t *);
81 static void slram_unpoint(struct mtd_info *, loff_t, size_t);
82 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
83 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
84 
85 static 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 
107 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
108 		size_t *retlen, void **virt, resource_size_t *phys)
109 {
110 	slram_priv_t *priv = mtd->priv;
111 
112 	/* can we return a physical address with this driver? */
113 	if (phys)
114 		return -EINVAL;
115 
116 	if (from + len > mtd->size)
117 		return -EINVAL;
118 
119 	*virt = priv->start + from;
120 	*retlen = len;
121 	return(0);
122 }
123 
124 static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
125 {
126 }
127 
128 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
129 		size_t *retlen, u_char *buf)
130 {
131 	slram_priv_t *priv = mtd->priv;
132 
133 	if (from > mtd->size)
134 		return -EINVAL;
135 
136 	if (from + len > mtd->size)
137 		len = mtd->size - from;
138 
139 	memcpy(buf, priv->start + from, len);
140 
141 	*retlen = len;
142 	return(0);
143 }
144 
145 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
146 		size_t *retlen, const u_char *buf)
147 {
148 	slram_priv_t *priv = mtd->priv;
149 
150 	if (to + len > mtd->size)
151 		return -EINVAL;
152 
153 	memcpy(priv->start + to, buf, len);
154 
155 	*retlen = len;
156 	return(0);
157 }
158 
159 /*====================================================================*/
160 
161 static int register_device(char *name, unsigned long start, unsigned long length)
162 {
163 	slram_mtd_list_t **curmtd;
164 
165 	curmtd = &slram_mtdlist;
166 	while (*curmtd) {
167 		curmtd = &(*curmtd)->next;
168 	}
169 
170 	*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
171 	if (!(*curmtd)) {
172 		E("slram: Cannot allocate new MTD device.\n");
173 		return(-ENOMEM);
174 	}
175 	(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
176 	(*curmtd)->next = NULL;
177 
178 	if ((*curmtd)->mtdinfo)	{
179 		(*curmtd)->mtdinfo->priv =
180 			kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
181 
182 		if (!(*curmtd)->mtdinfo->priv) {
183 			kfree((*curmtd)->mtdinfo);
184 			(*curmtd)->mtdinfo = NULL;
185 		}
186 	}
187 
188 	if (!(*curmtd)->mtdinfo) {
189 		E("slram: Cannot allocate new MTD device.\n");
190 		return(-ENOMEM);
191 	}
192 
193 	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
194 				ioremap(start, length))) {
195 		E("slram: ioremap failed\n");
196 		return -EIO;
197 	}
198 	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
199 		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
200 
201 
202 	(*curmtd)->mtdinfo->name = name;
203 	(*curmtd)->mtdinfo->size = length;
204 	(*curmtd)->mtdinfo->flags = 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 	(*curmtd)->mtdinfo->writesize = 1;
214 
215 	if (add_mtd_device((*curmtd)->mtdinfo))	{
216 		E("slram: Failed to register new device\n");
217 		iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
218 		kfree((*curmtd)->mtdinfo->priv);
219 		kfree((*curmtd)->mtdinfo);
220 		return(-EAGAIN);
221 	}
222 	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
223 			(start / 1024), ((start + length) / 1024));
224 	T("slram: Mapped from 0x%p to 0x%p\n",
225 			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
226 			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
227 	return(0);
228 }
229 
230 static void unregister_devices(void)
231 {
232 	slram_mtd_list_t *nextitem;
233 
234 	while (slram_mtdlist) {
235 		nextitem = slram_mtdlist->next;
236 		del_mtd_device(slram_mtdlist->mtdinfo);
237 		iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
238 		kfree(slram_mtdlist->mtdinfo->priv);
239 		kfree(slram_mtdlist->mtdinfo);
240 		kfree(slram_mtdlist);
241 		slram_mtdlist = nextitem;
242 	}
243 }
244 
245 static unsigned long handle_unit(unsigned long value, char *unit)
246 {
247 	if ((*unit == 'M') || (*unit == 'm')) {
248 		return(value * 1024 * 1024);
249 	} else if ((*unit == 'K') || (*unit == 'k')) {
250 		return(value * 1024);
251 	}
252 	return(value);
253 }
254 
255 static int parse_cmdline(char *devname, char *szstart, char *szlength)
256 {
257 	char *buffer;
258 	unsigned long devstart;
259 	unsigned long devlength;
260 
261 	if ((!devname) || (!szstart) || (!szlength)) {
262 		unregister_devices();
263 		return(-EINVAL);
264 	}
265 
266 	devstart = simple_strtoul(szstart, &buffer, 0);
267 	devstart = handle_unit(devstart, buffer);
268 
269 	if (*(szlength) != '+') {
270 		devlength = simple_strtoul(szlength, &buffer, 0);
271 		devlength = handle_unit(devlength, buffer) - devstart;
272 	} else {
273 		devlength = simple_strtoul(szlength + 1, &buffer, 0);
274 		devlength = handle_unit(devlength, buffer);
275 	}
276 	T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
277 			devname, devstart, devlength);
278 	if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
279 		E("slram: Illegal start / length parameter.\n");
280 		return(-EINVAL);
281 	}
282 
283 	if ((devstart = register_device(devname, devstart, devlength))){
284 		unregister_devices();
285 		return((int)devstart);
286 	}
287 	return(0);
288 }
289 
290 #ifndef MODULE
291 
292 static int __init mtd_slram_setup(char *str)
293 {
294 	map = str;
295 	return(1);
296 }
297 
298 __setup("slram=", mtd_slram_setup);
299 
300 #endif
301 
302 static int init_slram(void)
303 {
304 	char *devname;
305 	int i;
306 
307 #ifndef MODULE
308 	char *devstart;
309 	char *devlength;
310 
311 	i = 0;
312 
313 	if (!map) {
314 		E("slram: not enough parameters.\n");
315 		return(-EINVAL);
316 	}
317 	while (map) {
318 		devname = devstart = devlength = NULL;
319 
320 		if (!(devname = strsep(&map, ","))) {
321 			E("slram: No devicename specified.\n");
322 			break;
323 		}
324 		T("slram: devname = %s\n", devname);
325 		if ((!map) || (!(devstart = strsep(&map, ",")))) {
326 			E("slram: No devicestart specified.\n");
327 		}
328 		T("slram: devstart = %s\n", devstart);
329 		if ((!map) || (!(devlength = strsep(&map, ",")))) {
330 			E("slram: No devicelength / -end specified.\n");
331 		}
332 		T("slram: devlength = %s\n", devlength);
333 		if (parse_cmdline(devname, devstart, devlength) != 0) {
334 			return(-EINVAL);
335 		}
336 	}
337 #else
338 	int count;
339 
340 	for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
341 			count++) {
342 	}
343 
344 	if ((count % 3 != 0) || (count == 0)) {
345 		E("slram: not enough parameters.\n");
346 		return(-EINVAL);
347 	}
348 	for (i = 0; i < (count / 3); i++) {
349 		devname = map[i * 3];
350 
351 		if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
352 			return(-EINVAL);
353 		}
354 
355 	}
356 #endif /* !MODULE */
357 
358 	return(0);
359 }
360 
361 static void __exit cleanup_slram(void)
362 {
363 	unregister_devices();
364 }
365 
366 module_init(init_slram);
367 module_exit(cleanup_slram);
368 
369 MODULE_LICENSE("GPL");
370 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
371 MODULE_DESCRIPTION("MTD driver for uncached system RAM");
372