1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) ???? Jochen Schäuble <psionic@psionic.de>
4 * Copyright (c) 2003-2004 Joern Engel <joern@wh.fh-wedel.de>
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
16 * phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
30 struct phram_mtd_list {
32 struct list_head list;
35 static LIST_HEAD(phram_list);
37 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
39 u_char *start = mtd->priv;
41 memset(start + instr->addr, 0xff, instr->len);
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)
49 *virt = mtd->priv + from;
54 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
59 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
60 size_t *retlen, u_char *buf)
62 u_char *start = mtd->priv;
64 memcpy(buf, start + from, len);
69 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
70 size_t *retlen, const u_char *buf)
72 u_char *start = mtd->priv;
74 memcpy(start + to, buf, len);
79 static void unregister_devices(void)
81 struct phram_mtd_list *this, *safe;
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);
91 static int register_device(char *name, phys_addr_t start, size_t len)
93 struct phram_mtd_list *new;
96 new = kzalloc(sizeof(*new), GFP_KERNEL);
101 new->mtd.priv = ioremap(start, len);
102 if (!new->mtd.priv) {
103 pr_err("ioremap failed\n");
108 new->mtd.name = name;
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;
122 if (mtd_device_register(&new->mtd, NULL, 0)) {
123 pr_err("Failed to register new device\n");
127 list_add_tail(&new->list, &phram_list);
131 iounmap(new->mtd.priv);
138 static int parse_num64(uint64_t *num64, char *token)
145 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
147 if (token[len - 1] == 'i') {
148 switch (token[len - 2]) {
165 ret = kstrtou64(token, 0, num64);
171 static int parse_name(char **pname, const char *token)
176 len = strlen(token) + 1;
180 name = kstrdup(token, GFP_KERNEL);
189 static inline void kill_final_newline(char *str)
191 char *newline = strrchr(str, '\n');
193 if (newline && !newline[1])
198 #define parse_err(fmt, args...) do { \
199 pr_err(fmt , ## args); \
204 static int phram_init_called;
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
211 * Example: phram.phram=rootfs,0xa0000000,512Mi
213 static char phram_paramline[64 + 20 + 20];
216 static int phram_setup(const char *val)
218 char buf[64 + 20 + 20], *str = buf;
225 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
226 parse_err("parameter too long\n");
229 kill_final_newline(str);
231 for (i = 0; i < 3; i++)
232 token[i] = strsep(&str, ",");
235 parse_err("too many arguments\n");
238 parse_err("not enough arguments\n");
240 ret = parse_name(&name, token[0]);
244 ret = parse_num64(&start, token[1]);
247 parse_err("illegal start address\n");
250 ret = parse_num64(&len, token[2]);
253 parse_err("illegal device length\n");
256 ret = register_device(name, start, len);
258 pr_info("%s device: %#llx at %#llx\n", name, len, start);
265 static int phram_param_call(const char *val, const struct kernel_param *kp)
268 return phram_setup(val);
271 * If more parameters are later passed in via
272 * /sys/module/phram/parameters/phram
273 * and init_phram() has already been called,
274 * we can parse the argument now.
277 if (phram_init_called)
278 return phram_setup(val);
281 * During early boot stage, we only save the parameters
282 * here. We must parse them later: if the param passed
283 * from kernel boot command line, phram_param_call() is
284 * called so early that it is not possible to resolve
285 * the device (even kmalloc() fails). Defer that work to
289 if (strlen(val) >= sizeof(phram_paramline))
291 strcpy(phram_paramline, val);
297 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
298 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
301 static int __init init_phram(void)
306 if (phram_paramline[0])
307 ret = phram_setup(phram_paramline);
308 phram_init_called = 1;
314 static void __exit cleanup_phram(void)
316 unregister_devices();
319 module_init(init_phram);
320 module_exit(cleanup_phram);
322 MODULE_LICENSE("GPL");
323 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
324 MODULE_DESCRIPTION("MTD driver for physical RAM");