// SPDX-License-Identifier: GPL-2.0-only
/**
* Copyright (c) ???? Jochen Schäuble <psionic@psionic.de>
* Copyright (c) 2003-2004 Joern Engel <joern@wh.fh-wedel.de>
*
* Usage:
*
* one commend line parameter per device, each in the form:
* phram=<name>,<start>,<len>
* <name> may be up to 63 characters.
* <start> and <len> can be octal, decimal or hexadecimal. If followed
* by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
* gigabytes.
*
* Example:
* phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/io.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
struct phram_mtd_list {
struct mtd_info mtd;
struct list_head list;
};
static LIST_HEAD(phram_list);
static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
u_char *start = mtd->priv;
memset(start + instr->addr, 0xff, instr->len);
return 0;
}
static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, void **virt, resource_size_t *phys)
{
*virt = mtd->priv + from;
*retlen = len;
return 0;
}
static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
return 0;
}
static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, u_char *buf)
{
u_char *start = mtd->priv;
memcpy(buf, start + from, len);
*retlen = len;
return 0;
}
static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
u_char *start = mtd->priv;
memcpy(start + to, buf, len);
*retlen = len;
return 0;
}
static void unregister_devices(void)
{
struct phram_mtd_list *this, *safe;
list_for_each_entry_safe(this, safe, &phram_list, list) {
mtd_device_unregister(&this->mtd);
iounmap(this->mtd.priv);
kfree(this->mtd.name);
kfree(this);
}
}
static int register_device(char *name, phys_addr_t start, size_t len)
{
struct phram_mtd_list *new;
int ret = -ENOMEM;
new = kzalloc(sizeof(*new), GFP_KERNEL);
if (!new)
goto out0;
ret = -EIO;
new->mtd.priv = ioremap(start, len);
if (!new->mtd.priv) {
pr_err("ioremap failed\n");
goto out1;
}
new->mtd.name = name;
new->mtd.size = len;
new->mtd.flags = MTD_CAP_RAM;
new->mtd._erase = phram_erase;
new->mtd._point = phram_point;
new->mtd._unpoint = phram_unpoint;
new->mtd._read = phram_read;
new->mtd._write = phram_write;
new->mtd.owner = THIS_MODULE;
new->mtd.type = MTD_RAM;
new->mtd.erasesize = PAGE_SIZE;
new->mtd.writesize = 1;
ret = -EAGAIN;
if (mtd_device_register(&new->mtd, NULL, 0)) {
pr_err("Failed to register new device\n");
goto out2;
}
list_add_tail(&new->list, &phram_list);
return 0;
out2:
iounmap(new->mtd.priv);
out1:
kfree(new);
out0:
return ret;
}
static int parse_num64(uint64_t *num64, char *token)
{
size_t len;
int shift = 0;
int ret;
len = strlen(token);
/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
if (len > 2) {
if (token[len - 1] == 'i') {
switch (token[len - 2]) {
case 'G':
shift += 10;
/* fall through */
case 'M':
shift += 10;
/* fall through */
case 'k':
shift += 10;
token[len - 2] = 0;
break;
default:
return -EINVAL;
}
}
}
ret = kstrtou64(token, 0, num64);
*num64 <<= shift;
return ret;
}
static int parse_name(char **pname, const char *token)
{
size_t len;
char *name;
len = strlen(token) + 1;
if (len > 64)
return -ENOSPC;
name = kstrdup(token, GFP_KERNEL);
if (!name)
return -ENOMEM;
*pname = name;
return 0;
}
static inline void kill_final_newline(char *str)
{
char *newline = strrchr(str, '\n');
if (newline && !newline[1])
*newline = 0;
}
#define parse_err(fmt, args...) do { \
pr_err(fmt , ## args); \
return 1; \
} while (0)
#ifndef MODULE
static int phram_init_called;
/*
* This shall contain the module parameter if any. It is of the form:
* - phram=<device>,<address>,<size> for module case
* - phram.phram=<device>,<address>,<size> for built-in case
* We leave 64 bytes for the device name, 20 for the address and 20 for the
* size.
* Example: phram.phram=rootfs,0xa0000000,512Mi
*/
static char phram_paramline[64 + 20 + 20];
#endif
static int phram_setup(const char *val)
{
char buf[64 + 20 + 20], *str = buf;
char *token[3];
char *name;
uint64_t start;
uint64_t len;
int i, ret;
if (strnlen(val, sizeof(buf)) >= sizeof(buf))
parse_err("parameter too long\n");
strcpy(str, val);
kill_final_newline(str);
for (i = 0; i < 3; i++)
token[i] = strsep(&str, ",");
if (str)
parse_err("too many arguments\n");
if (!token[2])
parse_err("not enough arguments\n");
ret = parse_name(&name, token[0]);
if (ret)
return ret;
ret = parse_num64(&start, token[1]);
if (ret) {
kfree(name);
parse_err("illegal start address\n");
}
ret = parse_num64(&len, token[2]);
if (ret) {
kfree(name);
parse_err("illegal device length\n");
}
ret = register_device(name, start, len);
if (!ret)
pr_info("%s device: %#llx at %#llx\n", name, len, start);
else
kfree(name);
return ret;
}
static int phram_param_call(const char *val, const struct kernel_param *kp)
{
#ifdef MODULE
return phram_setup(val);
#else
/*
* If more parameters are later passed in via
* /sys/module/phram/parameters/phram
* and init_phram() has already been called,
* we can parse the argument now.
*/
if (phram_init_called)
return phram_setup(val);
/*
* During early boot stage, we only save the parameters
* here. We must parse them later: if the param passed
* from kernel boot command line, phram_param_call() is
* called so early that it is not possible to resolve
* the device (even kmalloc() fails). Defer that work to
* phram_setup().
*/
if (strlen(val) >= sizeof(phram_paramline))
return -ENOSPC;
strcpy(phram_paramline, val);
return 0;
#endif
}
module_param_call(phram, phram_param_call, NULL, NULL, 000);
MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
static int __init init_phram(void)
{
int ret = 0;
#ifndef MODULE
if (phram_paramline[0])
ret = phram_setup(phram_paramline);
phram_init_called = 1;
#endif
return ret;
}
static void __exit cleanup_phram(void)
{
unregister_devices();
}
module_init(init_phram);
module_exit(cleanup_phram);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
MODULE_DESCRIPTION("MTD driver for physical RAM");
