1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) ???? Jochen Schäuble <psionic@psionic.de>
4 * Copyright (c) 2003-2004 Joern Engel <joern@wh.fh-wedel.de>
5 *
6 * Usage:
7 *
8 * one commend line parameter per device, each in the form:
9 * phram=<name>,<start>,<len>[,<erasesize>]
10 * <name> may be up to 63 characters.
11 * <start>, <len>, and <erasesize> can be octal, decimal or hexadecimal. If followed
12 * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
13 * gigabytes. <erasesize> is optional and defaults to PAGE_SIZE.
14 *
15 * Example:
16 * phram=swap,64Mi,128Mi phram=test,900Mi,1Mi,64Ki
17 */
18
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/io.h>
22 #include <linux/init.h>
23 #include <linux/kernel.h>
24 #include <linux/list.h>
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/slab.h>
28 #include <linux/mtd/mtd.h>
29 #include <asm/div64.h>
30
31 struct phram_mtd_list {
32 struct mtd_info mtd;
33 struct list_head list;
34 };
35
36 static LIST_HEAD(phram_list);
37
phram_erase(struct mtd_info * mtd,struct erase_info * instr)38 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
39 {
40 u_char *start = mtd->priv;
41
42 memset(start + instr->addr, 0xff, instr->len);
43
44 return 0;
45 }
46
phram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,void ** virt,resource_size_t * phys)47 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
48 size_t *retlen, void **virt, resource_size_t *phys)
49 {
50 *virt = mtd->priv + from;
51 *retlen = len;
52 return 0;
53 }
54
phram_unpoint(struct mtd_info * mtd,loff_t from,size_t len)55 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
56 {
57 return 0;
58 }
59
phram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)60 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
61 size_t *retlen, u_char *buf)
62 {
63 u_char *start = mtd->priv;
64
65 memcpy(buf, start + from, len);
66 *retlen = len;
67 return 0;
68 }
69
phram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)70 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
71 size_t *retlen, const u_char *buf)
72 {
73 u_char *start = mtd->priv;
74
75 memcpy(start + to, buf, len);
76 *retlen = len;
77 return 0;
78 }
79
unregister_devices(void)80 static void unregister_devices(void)
81 {
82 struct phram_mtd_list *this, *safe;
83
84 list_for_each_entry_safe(this, safe, &phram_list, list) {
85 mtd_device_unregister(&this->mtd);
86 iounmap(this->mtd.priv);
87 kfree(this->mtd.name);
88 kfree(this);
89 }
90 }
91
register_device(char * name,phys_addr_t start,size_t len,uint32_t erasesize)92 static int register_device(char *name, phys_addr_t start, size_t len, uint32_t erasesize)
93 {
94 struct phram_mtd_list *new;
95 int ret = -ENOMEM;
96
97 new = kzalloc(sizeof(*new), GFP_KERNEL);
98 if (!new)
99 goto out0;
100
101 ret = -EIO;
102 new->mtd.priv = ioremap(start, len);
103 if (!new->mtd.priv) {
104 pr_err("ioremap failed\n");
105 goto out1;
106 }
107
108
109 new->mtd.name = name;
110 new->mtd.size = len;
111 new->mtd.flags = MTD_CAP_RAM;
112 new->mtd._erase = phram_erase;
113 new->mtd._point = phram_point;
114 new->mtd._unpoint = phram_unpoint;
115 new->mtd._read = phram_read;
116 new->mtd._write = phram_write;
117 new->mtd.owner = THIS_MODULE;
118 new->mtd.type = MTD_RAM;
119 new->mtd.erasesize = erasesize;
120 new->mtd.writesize = 1;
121
122 ret = -EAGAIN;
123 if (mtd_device_register(&new->mtd, NULL, 0)) {
124 pr_err("Failed to register new device\n");
125 goto out2;
126 }
127
128 list_add_tail(&new->list, &phram_list);
129 return 0;
130
131 out2:
132 iounmap(new->mtd.priv);
133 out1:
134 kfree(new);
135 out0:
136 return ret;
137 }
138
parse_num64(uint64_t * num64,char * token)139 static int parse_num64(uint64_t *num64, char *token)
140 {
141 size_t len;
142 int shift = 0;
143 int ret;
144
145 len = strlen(token);
146 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
147 if (len > 2) {
148 if (token[len - 1] == 'i') {
149 switch (token[len - 2]) {
150 case 'G':
151 shift += 10;
152 fallthrough;
153 case 'M':
154 shift += 10;
155 fallthrough;
156 case 'k':
157 shift += 10;
158 token[len - 2] = 0;
159 break;
160 default:
161 return -EINVAL;
162 }
163 }
164 }
165
166 ret = kstrtou64(token, 0, num64);
167 *num64 <<= shift;
168
169 return ret;
170 }
171
parse_name(char ** pname,const char * token)172 static int parse_name(char **pname, const char *token)
173 {
174 size_t len;
175 char *name;
176
177 len = strlen(token) + 1;
178 if (len > 64)
179 return -ENOSPC;
180
181 name = kstrdup(token, GFP_KERNEL);
182 if (!name)
183 return -ENOMEM;
184
185 *pname = name;
186 return 0;
187 }
188
189
kill_final_newline(char * str)190 static inline void kill_final_newline(char *str)
191 {
192 char *newline = strrchr(str, '\n');
193
194 if (newline && !newline[1])
195 *newline = 0;
196 }
197
198
199 #define parse_err(fmt, args...) do { \
200 pr_err(fmt , ## args); \
201 return 1; \
202 } while (0)
203
204 #ifndef MODULE
205 static int phram_init_called;
206 /*
207 * This shall contain the module parameter if any. It is of the form:
208 * - phram=<device>,<address>,<size>[,<erasesize>] for module case
209 * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case
210 * We leave 64 bytes for the device name, 20 for the address , 20 for the
211 * size and 20 for the erasesize.
212 * Example: phram.phram=rootfs,0xa0000000,512Mi,65536
213 */
214 static char phram_paramline[64 + 20 + 20 + 20];
215 #endif
216
phram_setup(const char * val)217 static int phram_setup(const char *val)
218 {
219 char buf[64 + 20 + 20 + 20], *str = buf;
220 char *token[4];
221 char *name;
222 uint64_t start;
223 uint64_t len;
224 uint64_t erasesize = PAGE_SIZE;
225 uint32_t rem;
226 int i, ret;
227
228 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
229 parse_err("parameter too long\n");
230
231 strcpy(str, val);
232 kill_final_newline(str);
233
234 for (i = 0; i < 4; i++)
235 token[i] = strsep(&str, ",");
236
237 if (str)
238 parse_err("too many arguments\n");
239
240 if (!token[2])
241 parse_err("not enough arguments\n");
242
243 ret = parse_name(&name, token[0]);
244 if (ret)
245 return ret;
246
247 ret = parse_num64(&start, token[1]);
248 if (ret) {
249 parse_err("illegal start address\n");
250 goto error;
251 }
252
253 ret = parse_num64(&len, token[2]);
254 if (ret) {
255 parse_err("illegal device length\n");
256 goto error;
257 }
258
259 if (token[3]) {
260 ret = parse_num64(&erasesize, token[3]);
261 if (ret) {
262 parse_err("illegal erasesize\n");
263 goto error;
264 }
265 }
266
267 if (erasesize)
268 div_u64_rem(len, (uint32_t)erasesize, &rem);
269
270 if (len == 0 || erasesize == 0 || erasesize > len
271 || erasesize > UINT_MAX || rem) {
272 parse_err("illegal erasesize or len\n");
273 ret = -EINVAL;
274 goto error;
275 }
276
277 ret = register_device(name, start, len, (uint32_t)erasesize);
278 if (ret)
279 goto error;
280
281 pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);
282 return 0;
283
284 error:
285 kfree(name);
286 return ret;
287 }
288
phram_param_call(const char * val,const struct kernel_param * kp)289 static int phram_param_call(const char *val, const struct kernel_param *kp)
290 {
291 #ifdef MODULE
292 return phram_setup(val);
293 #else
294 /*
295 * If more parameters are later passed in via
296 * /sys/module/phram/parameters/phram
297 * and init_phram() has already been called,
298 * we can parse the argument now.
299 */
300
301 if (phram_init_called)
302 return phram_setup(val);
303
304 /*
305 * During early boot stage, we only save the parameters
306 * here. We must parse them later: if the param passed
307 * from kernel boot command line, phram_param_call() is
308 * called so early that it is not possible to resolve
309 * the device (even kmalloc() fails). Defer that work to
310 * phram_setup().
311 */
312
313 if (strlen(val) >= sizeof(phram_paramline))
314 return -ENOSPC;
315 strcpy(phram_paramline, val);
316
317 return 0;
318 #endif
319 }
320
321 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
322 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
323
324
init_phram(void)325 static int __init init_phram(void)
326 {
327 int ret = 0;
328
329 #ifndef MODULE
330 if (phram_paramline[0])
331 ret = phram_setup(phram_paramline);
332 phram_init_called = 1;
333 #endif
334
335 return ret;
336 }
337
cleanup_phram(void)338 static void __exit cleanup_phram(void)
339 {
340 unregister_devices();
341 }
342
343 module_init(init_phram);
344 module_exit(cleanup_phram);
345
346 MODULE_LICENSE("GPL");
347 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
348 MODULE_DESCRIPTION("MTD driver for physical RAM");
349