linux/drivers/mtd/devices/slram.c
Roy Franz cb9e20633d mtd: slram: use memremap() instead of ioremap()
Convert slram to use memremap() to map the memory it uses to back an MTD
device, as this is the proper interface for mapping memory. This change
enables normal memory to be used to back an MTD device on arm64, as arm64
prevents ioremap() being used on normal memory.

Signed-off-by: Roy Franz <roy.franz@cavium.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: David Daney <david.daney@cavium.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2017-11-13 21:39:16 +01:00

349 lines
8.7 KiB
C

/*======================================================================
This driver provides a method to access memory not used by the kernel
itself (i.e. if the kernel commandline mem=xxx is used). To actually
use slram at least mtdblock or mtdchar is required (for block or
character device access).
Usage:
if compiled as loadable module:
modprobe slram map=<name>,<start>,<end/offset>
if statically linked into the kernel use the following kernel cmd.line
slram=<name>,<start>,<end/offset>
<name>: name of the device that will be listed in /proc/mtd
<start>: start of the memory region, decimal or hex (0xabcdef)
<end/offset>: end of the memory region. It's possible to use +0x1234
to specify the offset instead of the absolute address
NOTE:
With slram it's only possible to map a contiguous memory region. Therefore
if there's a device mapped somewhere in the region specified slram will
fail to load (see kernel log if modprobe fails).
-
Jochen Schaeuble <psionic@psionic.de>
======================================================================*/
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/mtd/mtd.h>
#define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */
#define SLRAM_BLK_SZ 0x4000
#define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
#define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
typedef struct slram_priv {
u_char *start;
u_char *end;
} slram_priv_t;
typedef struct slram_mtd_list {
struct mtd_info *mtdinfo;
struct slram_mtd_list *next;
} slram_mtd_list_t;
#ifdef MODULE
static char *map[SLRAM_MAX_DEVICES_PARAMS];
module_param_array(map, charp, NULL, 0);
MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
#else
static char *map;
#endif
static slram_mtd_list_t *slram_mtdlist = NULL;
static int slram_erase(struct mtd_info *, struct erase_info *);
static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
resource_size_t *);
static int slram_unpoint(struct mtd_info *, loff_t, size_t);
static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
slram_priv_t *priv = mtd->priv;
memset(priv->start + instr->addr, 0xff, instr->len);
/* This'll catch a few races. Free the thing before returning :)
* I don't feel at all ashamed. This kind of thing is possible anyway
* with flash, but unlikely.
*/
instr->state = MTD_ERASE_DONE;
mtd_erase_callback(instr);
return(0);
}
static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, void **virt, resource_size_t *phys)
{
slram_priv_t *priv = mtd->priv;
*virt = priv->start + from;
*retlen = len;
return(0);
}
static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
return 0;
}
static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, u_char *buf)
{
slram_priv_t *priv = mtd->priv;
memcpy(buf, priv->start + from, len);
*retlen = len;
return(0);
}
static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
slram_priv_t *priv = mtd->priv;
memcpy(priv->start + to, buf, len);
*retlen = len;
return(0);
}
/*====================================================================*/
static int register_device(char *name, unsigned long start, unsigned long length)
{
slram_mtd_list_t **curmtd;
curmtd = &slram_mtdlist;
while (*curmtd) {
curmtd = &(*curmtd)->next;
}
*curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
if (!(*curmtd)) {
E("slram: Cannot allocate new MTD device.\n");
return(-ENOMEM);
}
(*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
(*curmtd)->next = NULL;
if ((*curmtd)->mtdinfo) {
(*curmtd)->mtdinfo->priv =
kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
if (!(*curmtd)->mtdinfo->priv) {
kfree((*curmtd)->mtdinfo);
(*curmtd)->mtdinfo = NULL;
}
}
if (!(*curmtd)->mtdinfo) {
E("slram: Cannot allocate new MTD device.\n");
return(-ENOMEM);
}
if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
memremap(start, length,
MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) {
E("slram: memremap failed\n");
return -EIO;
}
((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
(*curmtd)->mtdinfo->name = name;
(*curmtd)->mtdinfo->size = length;
(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
(*curmtd)->mtdinfo->_erase = slram_erase;
(*curmtd)->mtdinfo->_point = slram_point;
(*curmtd)->mtdinfo->_unpoint = slram_unpoint;
(*curmtd)->mtdinfo->_read = slram_read;
(*curmtd)->mtdinfo->_write = slram_write;
(*curmtd)->mtdinfo->owner = THIS_MODULE;
(*curmtd)->mtdinfo->type = MTD_RAM;
(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
(*curmtd)->mtdinfo->writesize = 1;
if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0)) {
E("slram: Failed to register new device\n");
memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
kfree((*curmtd)->mtdinfo->priv);
kfree((*curmtd)->mtdinfo);
return(-EAGAIN);
}
T("slram: Registered device %s from %luKiB to %luKiB\n", name,
(start / 1024), ((start + length) / 1024));
T("slram: Mapped from 0x%p to 0x%p\n",
((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
return(0);
}
static void unregister_devices(void)
{
slram_mtd_list_t *nextitem;
while (slram_mtdlist) {
nextitem = slram_mtdlist->next;
mtd_device_unregister(slram_mtdlist->mtdinfo);
memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
kfree(slram_mtdlist->mtdinfo->priv);
kfree(slram_mtdlist->mtdinfo);
kfree(slram_mtdlist);
slram_mtdlist = nextitem;
}
}
static unsigned long handle_unit(unsigned long value, char *unit)
{
if ((*unit == 'M') || (*unit == 'm')) {
return(value * 1024 * 1024);
} else if ((*unit == 'K') || (*unit == 'k')) {
return(value * 1024);
}
return(value);
}
static int parse_cmdline(char *devname, char *szstart, char *szlength)
{
char *buffer;
unsigned long devstart;
unsigned long devlength;
if ((!devname) || (!szstart) || (!szlength)) {
unregister_devices();
return(-EINVAL);
}
devstart = simple_strtoul(szstart, &buffer, 0);
devstart = handle_unit(devstart, buffer);
if (*(szlength) != '+') {
devlength = simple_strtoul(szlength, &buffer, 0);
devlength = handle_unit(devlength, buffer);
if (devlength < devstart)
goto err_out;
devlength -= devstart;
} else {
devlength = simple_strtoul(szlength + 1, &buffer, 0);
devlength = handle_unit(devlength, buffer);
}
T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
devname, devstart, devlength);
if (devlength % SLRAM_BLK_SZ != 0)
goto err_out;
if ((devstart = register_device(devname, devstart, devlength))){
unregister_devices();
return((int)devstart);
}
return(0);
err_out:
E("slram: Illegal length parameter.\n");
return(-EINVAL);
}
#ifndef MODULE
static int __init mtd_slram_setup(char *str)
{
map = str;
return(1);
}
__setup("slram=", mtd_slram_setup);
#endif
static int __init init_slram(void)
{
char *devname;
#ifndef MODULE
char *devstart;
char *devlength;
if (!map) {
E("slram: not enough parameters.\n");
return(-EINVAL);
}
while (map) {
devname = devstart = devlength = NULL;
if (!(devname = strsep(&map, ","))) {
E("slram: No devicename specified.\n");
break;
}
T("slram: devname = %s\n", devname);
if ((!map) || (!(devstart = strsep(&map, ",")))) {
E("slram: No devicestart specified.\n");
}
T("slram: devstart = %s\n", devstart);
if ((!map) || (!(devlength = strsep(&map, ",")))) {
E("slram: No devicelength / -end specified.\n");
}
T("slram: devlength = %s\n", devlength);
if (parse_cmdline(devname, devstart, devlength) != 0) {
return(-EINVAL);
}
}
#else
int count;
int i;
for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
count++) {
}
if ((count % 3 != 0) || (count == 0)) {
E("slram: not enough parameters.\n");
return(-EINVAL);
}
for (i = 0; i < (count / 3); i++) {
devname = map[i * 3];
if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
return(-EINVAL);
}
}
#endif /* !MODULE */
return(0);
}
static void __exit cleanup_slram(void)
{
unregister_devices();
}
module_init(init_slram);
module_exit(cleanup_slram);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
MODULE_DESCRIPTION("MTD driver for uncached system RAM");