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