1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) ????		Jochen Sch��uble <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
34struct phram_mtd_list {
35	struct mtd_info mtd;
36	struct list_head list;
37	bool cached;
38};
39
40static LIST_HEAD(phram_list);
41
42static 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
51static 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
59static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
60{
61	return 0;
62}
63
64static 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
74static 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
84static 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
100static 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
112static 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
124static 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
173out2:
174	phram_unmap(new);
175out1:
176	kfree(new);
177out0:
178	return ret;
179}
180
181static 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
214static 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
232static 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
247static 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 */
256static char phram_paramline[64 + 20 + 20 + 20];
257#endif
258
259static 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
330error:
331	kfree(name);
332	return ret;
333}
334
335static 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
367module_param_call(phram, phram_param_call, NULL, NULL, 0200);
368MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
369
370#ifdef CONFIG_OF
371static const struct of_device_id phram_of_match[] = {
372	{ .compatible = "phram" },
373	{}
374};
375MODULE_DEVICE_TABLE(of, phram_of_match);
376#endif
377
378static 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
391static void 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
400static struct platform_driver phram_driver = {
401	.probe		= phram_probe,
402	.remove_new	= phram_remove,
403	.driver		= {
404		.name		= "phram",
405		.of_match_table	= of_match_ptr(phram_of_match),
406	},
407};
408
409static int __init init_phram(void)
410{
411	int ret;
412
413	ret = platform_driver_register(&phram_driver);
414	if (ret)
415		return ret;
416
417#ifndef MODULE
418	if (phram_paramline[0])
419		ret = phram_setup(phram_paramline);
420	phram_init_called = 1;
421#endif
422
423	if (ret)
424		platform_driver_unregister(&phram_driver);
425
426	return ret;
427}
428
429static void __exit cleanup_phram(void)
430{
431	unregister_devices();
432	platform_driver_unregister(&phram_driver);
433}
434
435module_init(init_phram);
436module_exit(cleanup_phram);
437
438MODULE_LICENSE("GPL");
439MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
440MODULE_DESCRIPTION("MTD driver for physical RAM");
441