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