--- /dev/null
+/*======================================================================
+
+ 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 <asm/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 <asm/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 =
+ ioremap(start, length))) {
+ E("slram: ioremap 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");
+ iounmap(((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);
+ iounmap(((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");
Code Review / kvmfornfv.git / blobdiff