xref: /openbmc/linux/drivers/mtd/devices/phram.c (revision 9401911f)
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 #include <linux/platform_device.h>
31 #include <linux/of_address.h>
32 #include <linux/of.h>
33 
34 struct phram_mtd_list {
35 	struct mtd_info mtd;
36 	struct list_head list;
37 	bool cached;
38 };
39 
40 static LIST_HEAD(phram_list);
41 
phram_erase(struct mtd_info * mtd,struct erase_info * instr)42 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
43 {
44 	u_char *start = mtd->priv;
45 
46 	memset(start + instr->addr, 0xff, instr->len);
47 
48 	return 0;
49 }
50 
phram_point(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,void ** virt,resource_size_t * phys)51 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
52 		size_t *retlen, void **virt, resource_size_t *phys)
53 {
54 	*virt = mtd->priv + from;
55 	*retlen = len;
56 	return 0;
57 }
58 
phram_unpoint(struct mtd_info * mtd,loff_t from,size_t len)59 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
60 {
61 	return 0;
62 }
63 
phram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)64 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
65 		size_t *retlen, u_char *buf)
66 {
67 	u_char *start = mtd->priv;
68 
69 	memcpy(buf, start + from, len);
70 	*retlen = len;
71 	return 0;
72 }
73 
phram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)74 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
75 		size_t *retlen, const u_char *buf)
76 {
77 	u_char *start = mtd->priv;
78 
79 	memcpy(start + to, buf, len);
80 	*retlen = len;
81 	return 0;
82 }
83 
phram_map(struct phram_mtd_list * phram,phys_addr_t start,size_t len)84 static int phram_map(struct phram_mtd_list *phram, phys_addr_t start, size_t len)
85 {
86 	void *addr = NULL;
87 
88 	if (phram->cached)
89 		addr = memremap(start, len, MEMREMAP_WB);
90 	else
91 		addr = (void __force *)ioremap(start, len);
92 	if (!addr)
93 		return -EIO;
94 
95 	phram->mtd.priv = addr;
96 
97 	return 0;
98 }
99 
phram_unmap(struct phram_mtd_list * phram)100 static void phram_unmap(struct phram_mtd_list *phram)
101 {
102 	void *addr = phram->mtd.priv;
103 
104 	if (phram->cached) {
105 		memunmap(addr);
106 		return;
107 	}
108 
109 	iounmap((void __iomem *)addr);
110 }
111 
unregister_devices(void)112 static void unregister_devices(void)
113 {
114 	struct phram_mtd_list *this, *safe;
115 
116 	list_for_each_entry_safe(this, safe, &phram_list, list) {
117 		mtd_device_unregister(&this->mtd);
118 		phram_unmap(this);
119 		kfree(this->mtd.name);
120 		kfree(this);
121 	}
122 }
123 
register_device(struct platform_device * pdev,const char * name,phys_addr_t start,size_t len,uint32_t erasesize)124 static int register_device(struct platform_device *pdev, const char *name,
125 			   phys_addr_t start, size_t len, uint32_t erasesize)
126 {
127 	struct device_node *np = pdev ? pdev->dev.of_node : NULL;
128 	bool cached = np ? !of_property_read_bool(np, "no-map") : false;
129 	struct phram_mtd_list *new;
130 	int ret = -ENOMEM;
131 
132 	new = kzalloc(sizeof(*new), GFP_KERNEL);
133 	if (!new)
134 		goto out0;
135 
136 	new->cached = cached;
137 
138 	ret = phram_map(new, start, len);
139 	if (ret) {
140 		pr_err("ioremap failed\n");
141 		goto out1;
142 	}
143 
144 
145 	new->mtd.name = name;
146 	new->mtd.size = len;
147 	new->mtd.flags = MTD_CAP_RAM;
148 	new->mtd._erase = phram_erase;
149 	new->mtd._point = phram_point;
150 	new->mtd._unpoint = phram_unpoint;
151 	new->mtd._read = phram_read;
152 	new->mtd._write = phram_write;
153 	new->mtd.owner = THIS_MODULE;
154 	new->mtd.type = MTD_RAM;
155 	new->mtd.erasesize = erasesize;
156 	new->mtd.writesize = 1;
157 
158 	mtd_set_of_node(&new->mtd, np);
159 
160 	ret = -EAGAIN;
161 	if (mtd_device_register(&new->mtd, NULL, 0)) {
162 		pr_err("Failed to register new device\n");
163 		goto out2;
164 	}
165 
166 	if (pdev)
167 		platform_set_drvdata(pdev, new);
168 	else
169 		list_add_tail(&new->list, &phram_list);
170 
171 	return 0;
172 
173 out2:
174 	phram_unmap(new);
175 out1:
176 	kfree(new);
177 out0:
178 	return ret;
179 }
180 
parse_num64(uint64_t * num64,char * token)181 static int parse_num64(uint64_t *num64, char *token)
182 {
183 	size_t len;
184 	int shift = 0;
185 	int ret;
186 
187 	len = strlen(token);
188 	/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
189 	if (len > 2) {
190 		if (token[len - 1] == 'i') {
191 			switch (token[len - 2]) {
192 			case 'G':
193 				shift += 10;
194 				fallthrough;
195 			case 'M':
196 				shift += 10;
197 				fallthrough;
198 			case 'k':
199 				shift += 10;
200 				token[len - 2] = 0;
201 				break;
202 			default:
203 				return -EINVAL;
204 			}
205 		}
206 	}
207 
208 	ret = kstrtou64(token, 0, num64);
209 	*num64 <<= shift;
210 
211 	return ret;
212 }
213 
parse_name(char ** pname,const char * token)214 static int parse_name(char **pname, const char *token)
215 {
216 	size_t len;
217 	char *name;
218 
219 	len = strlen(token) + 1;
220 	if (len > 64)
221 		return -ENOSPC;
222 
223 	name = kstrdup(token, GFP_KERNEL);
224 	if (!name)
225 		return -ENOMEM;
226 
227 	*pname = name;
228 	return 0;
229 }
230 
231 
kill_final_newline(char * str)232 static inline void kill_final_newline(char *str)
233 {
234 	char *newline = strrchr(str, '\n');
235 
236 	if (newline && !newline[1])
237 		*newline = 0;
238 }
239 
240 
241 #define parse_err(fmt, args...) do {	\
242 	pr_err(fmt , ## args);	\
243 	return 1;		\
244 } while (0)
245 
246 #ifndef MODULE
247 static int phram_init_called;
248 /*
249  * This shall contain the module parameter if any. It is of the form:
250  * - phram=<device>,<address>,<size>[,<erasesize>] for module case
251  * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case
252  * We leave 64 bytes for the device name, 20 for the address , 20 for the
253  * size and 20 for the erasesize.
254  * Example: phram.phram=rootfs,0xa0000000,512Mi,65536
255  */
256 static char phram_paramline[64 + 20 + 20 + 20];
257 #endif
258 
phram_setup(const char * val)259 static int phram_setup(const char *val)
260 {
261 	char buf[64 + 20 + 20 + 20], *str = buf;
262 	char *token[4];
263 	char *name;
264 	uint64_t start;
265 	uint64_t len;
266 	uint64_t erasesize = PAGE_SIZE;
267 	uint32_t rem;
268 	int i, ret;
269 
270 	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
271 		parse_err("parameter too long\n");
272 
273 	strcpy(str, val);
274 	kill_final_newline(str);
275 
276 	for (i = 0; i < 4; i++)
277 		token[i] = strsep(&str, ",");
278 
279 	if (str)
280 		parse_err("too many arguments\n");
281 
282 	if (!token[2])
283 		parse_err("not enough arguments\n");
284 
285 	ret = parse_name(&name, token[0]);
286 	if (ret)
287 		return ret;
288 
289 	ret = parse_num64(&start, token[1]);
290 	if (ret) {
291 		parse_err("illegal start address\n");
292 		goto error;
293 	}
294 
295 	ret = parse_num64(&len, token[2]);
296 	if (ret) {
297 		parse_err("illegal device length\n");
298 		goto error;
299 	}
300 
301 	if (token[3]) {
302 		ret = parse_num64(&erasesize, token[3]);
303 		if (ret) {
304 			parse_err("illegal erasesize\n");
305 			goto error;
306 		}
307 	}
308 
309 	if (len == 0 || erasesize == 0 || erasesize > len
310 	    || erasesize > UINT_MAX) {
311 		parse_err("illegal erasesize or len\n");
312 		ret = -EINVAL;
313 		goto error;
314 	}
315 
316 	div_u64_rem(len, (uint32_t)erasesize, &rem);
317 	if (rem) {
318 		parse_err("len is not multiple of erasesize\n");
319 		ret = -EINVAL;
320 		goto error;
321 	}
322 
323 	ret = register_device(NULL, name, start, len, (uint32_t)erasesize);
324 	if (ret)
325 		goto error;
326 
327 	pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);
328 	return 0;
329 
330 error:
331 	kfree(name);
332 	return ret;
333 }
334 
phram_param_call(const char * val,const struct kernel_param * kp)335 static int phram_param_call(const char *val, const struct kernel_param *kp)
336 {
337 #ifdef MODULE
338 	return phram_setup(val);
339 #else
340 	/*
341 	 * If more parameters are later passed in via
342 	 * /sys/module/phram/parameters/phram
343 	 * and init_phram() has already been called,
344 	 * we can parse the argument now.
345 	 */
346 
347 	if (phram_init_called)
348 		return phram_setup(val);
349 
350 	/*
351 	 * During early boot stage, we only save the parameters
352 	 * here. We must parse them later: if the param passed
353 	 * from kernel boot command line, phram_param_call() is
354 	 * called so early that it is not possible to resolve
355 	 * the device (even kmalloc() fails). Defer that work to
356 	 * phram_setup().
357 	 */
358 
359 	if (strlen(val) >= sizeof(phram_paramline))
360 		return -ENOSPC;
361 	strcpy(phram_paramline, val);
362 
363 	return 0;
364 #endif
365 }
366 
367 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
368 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
369 
370 #ifdef CONFIG_OF
371 static const struct of_device_id phram_of_match[] = {
372 	{ .compatible = "phram" },
373 	{}
374 };
375 MODULE_DEVICE_TABLE(of, phram_of_match);
376 #endif
377 
phram_probe(struct platform_device * pdev)378 static int phram_probe(struct platform_device *pdev)
379 {
380 	struct resource *res;
381 
382 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
383 	if (!res)
384 		return -ENOMEM;
385 
386 	/* mtd_set_of_node() reads name from "label" */
387 	return register_device(pdev, NULL, res->start, resource_size(res),
388 			       PAGE_SIZE);
389 }
390 
phram_remove(struct platform_device * pdev)391 static int phram_remove(struct platform_device *pdev)
392 {
393 	struct phram_mtd_list *phram = platform_get_drvdata(pdev);
394 
395 	mtd_device_unregister(&phram->mtd);
396 	phram_unmap(phram);
397 	kfree(phram);
398 
399 	return 0;
400 }
401 
402 static struct platform_driver phram_driver = {
403 	.probe		= phram_probe,
404 	.remove		= phram_remove,
405 	.driver		= {
406 		.name		= "phram",
407 		.of_match_table	= of_match_ptr(phram_of_match),
408 	},
409 };
410 
init_phram(void)411 static int __init init_phram(void)
412 {
413 	int ret;
414 
415 	ret = platform_driver_register(&phram_driver);
416 	if (ret)
417 		return ret;
418 
419 #ifndef MODULE
420 	if (phram_paramline[0])
421 		ret = phram_setup(phram_paramline);
422 	phram_init_called = 1;
423 #endif
424 
425 	if (ret)
426 		platform_driver_unregister(&phram_driver);
427 
428 	return ret;
429 }
430 
cleanup_phram(void)431 static void __exit cleanup_phram(void)
432 {
433 	unregister_devices();
434 	platform_driver_unregister(&phram_driver);
435 }
436 
437 module_init(init_phram);
438 module_exit(cleanup_phram);
439 
440 MODULE_LICENSE("GPL");
441 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
442 MODULE_DESCRIPTION("MTD driver for physical RAM");
443