diff options
Diffstat (limited to 'drivers/mtd/devices/slram.c')
| -rw-r--r-- | drivers/mtd/devices/slram.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/drivers/mtd/devices/slram.c b/drivers/mtd/devices/slram.c new file mode 100644 index 000000000..aa38ecdff --- /dev/null +++ b/drivers/mtd/devices/slram.c @@ -0,0 +1,354 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*====================================================================== + + 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); + + 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; + slram_mtd_list_t *new_mtd; + struct mtd_info *mtdinfo; + slram_priv_t *priv; + int ret = -ENOMEM; + + curmtd = &slram_mtdlist; + while (*curmtd) { + curmtd = &(*curmtd)->next; + } + + new_mtd = kmalloc_obj(slram_mtd_list_t); + if (!new_mtd) { + E("slram: Cannot allocate new MTD device.\n"); + return(-ENOMEM); + } + new_mtd->next = NULL; + + mtdinfo = kzalloc_obj(struct mtd_info); + if (!mtdinfo) { + E("slram: Cannot allocate new MTD device.\n"); + goto err_free_list; + } + new_mtd->mtdinfo = mtdinfo; + + priv = kzalloc_obj(slram_priv_t); + if (!priv) { + E("slram: Cannot allocate new MTD device.\n"); + goto err_free_mtdinfo; + } + mtdinfo->priv = priv; + + priv->start = memremap(start, length, + MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC); + if (!priv->start) { + E("slram: memremap failed\n"); + ret = -EIO; + goto err_free_priv; + } + priv->end = priv->start + length; + + mtdinfo->name = name; + mtdinfo->size = length; + mtdinfo->flags = MTD_CAP_RAM; + mtdinfo->_erase = slram_erase; + mtdinfo->_point = slram_point; + mtdinfo->_unpoint = slram_unpoint; + mtdinfo->_read = slram_read; + mtdinfo->_write = slram_write; + mtdinfo->owner = THIS_MODULE; + mtdinfo->type = MTD_RAM; + mtdinfo->erasesize = SLRAM_BLK_SZ; + mtdinfo->writesize = 1; + + if (mtd_device_register(mtdinfo, NULL, 0)) { + E("slram: Failed to register new device\n"); + ret = -EAGAIN; + goto err_unmap; + } + *curmtd = new_mtd; + 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", priv->start, priv->end); + return 0; + +err_unmap: + memunmap(priv->start); +err_free_priv: + kfree(priv); +err_free_mtdinfo: + kfree(mtdinfo); +err_free_list: + kfree(new_mtd); + return ret; +} + +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"); + break; + } + T("slram: devstart = %s\n", devstart); + if ((!map) || (!(devlength = strsep(&map, ",")))) { + E("slram: No devicelength / -end specified.\n"); + break; + } + 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"); |