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