/*
* Xpram.c -- the S/390 expanded memory RAM-disk
*
* significant parts of this code are based on
* the sbull device driver presented in
* A. Rubini: Linux Device Drivers
*
* Author of XPRAM specific coding: Reinhard Buendgen
* buendgen@de.ibm.com
* Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
*
* External interfaces:
* Interfaces to linux kernel
* xpram_setup: read kernel parameters
* Device specific file operations
* xpram_iotcl
* xpram_open
*
* "ad-hoc" partitioning:
* the expanded memory can be partitioned among several devices
* (with different minors). The partitioning set up can be
* set by kernel or module parameters (int devs & int sizes[])
*
* Potential future improvements:
* generic hard disk support to replace ad-hoc partitioning
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ctype.h> /* isdigit, isxdigit */
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/hdreg.h> /* HDIO_GETGEO */
#include <linux/sysdev.h>
#include <linux/bio.h>
#include <asm/uaccess.h>
#define XPRAM_NAME "xpram"
#define XPRAM_DEVS 1 /* one partition */
#define XPRAM_MAX_DEVS 32 /* maximal number of devices (partitions) */
#define PRINT_DEBUG(x...) printk(KERN_DEBUG XPRAM_NAME " debug:" x)
#define PRINT_INFO(x...) printk(KERN_INFO XPRAM_NAME " info:" x)
#define PRINT_WARN(x...) printk(KERN_WARNING XPRAM_NAME " warning:" x)
#define PRINT_ERR(x...) printk(KERN_ERR XPRAM_NAME " error:" x)
typedef struct {
unsigned int size; /* size of xpram segment in pages */
unsigned int offset; /* start page of xpram segment */
} xpram_device_t;
static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
static unsigned int xpram_pages;
static int xpram_devs;
/*
* Parameter parsing functions.
*/
static int __initdata devs = XPRAM_DEVS;
static char __initdata *sizes[XPRAM_MAX_DEVS];
module_param(devs, int, 0);
module_param_array(sizes, charp, NULL, 0);
MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
"the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
MODULE_PARM_DESC(sizes, "list of device (partition) sizes " \
"the defaults are 0s \n" \
"All devices with size 0 equally partition the "
"remaining space on the expanded strorage not "
"claimed by explicit sizes\n");
MODULE_LICENSE("GPL");
/*
* Copy expanded memory page (4kB) into main memory
* Arguments
* page_addr: address of target page
* xpage_index: index of expandeded memory page
* Return value
* 0: if operation succeeds
* -EIO: if pgin failed
* -ENXIO: if xpram has vanished
*/
static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
{
int cc = 2; /* return unused cc 2 if pgin traps */
asm volatile(
" .insn rre,0xb22e0000,%1,%2\n" /* pgin %1,%2 */
"0: ipm %0\n"
" srl %0,28\n"
"1:\n"
EX_TABLE(0b,1b)
: "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
if (cc == 3)
return -ENXIO;
if (cc == 2)
return -ENXIO;
if (cc == 1)
return -EIO;
return 0;
}
/*
* Copy a 4kB page of main memory to an expanded memory page
* Arguments
* page_addr: address of source page
* xpage_index: index of expandeded memory page
* Return value
* 0: if operation succeeds
* -EIO: if pgout failed
* -ENXIO: if xpram has vanished
*/
static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
{
int cc = 2; /* return unused cc 2 if pgin traps */
asm volatile(
" .insn rre,0xb22f0000,%1,%2\n" /* pgout %1,%2 */
"0: ipm %0\n"
" srl %0,28\n"
"1:\n"
EX_TABLE(0b,1b)
: "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
if (cc == 3)
return -ENXIO;
if (cc == 2)
return -ENXIO;
if (cc == 1)
return -EIO;
return 0;
}
/*
* Check if xpram is available.
*/
static int __init xpram_present(void)
{
unsigned long mem_page;
int rc;
mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
if (!mem_page)
return -ENOMEM;
rc = xpram_page_in(mem_page, 0);
free_page(mem_page);
return rc ? -ENXIO : 0;
}
/*
* Return index of the last available xpram page.
*/
static unsigned long __init xpram_highest_page_index(void)
{
unsigned int page_index, add_bit;
unsigned long mem_page;
mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
if (!mem_page)
return 0;
page_index = 0;
add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
while (add_bit > 0) {
if (xpram_page_in(mem_page, page_index | add_bit) == 0)
page_index |= add_bit;
add_bit >>= 1;
}
free_page (mem_page);
return page_index;
}
/*
* Block device make request function.
*/
static int xpram_make_request(struct request_queue *q, struct bio *bio)
{
xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
struct bio_vec *bvec;
unsigned int index;
unsigned long page_addr;
unsigned long bytes;
int i;
if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
/* Request is not page-aligned. */
goto fail;
if ((bio->bi_size >> 12) > xdev->size)
/* Request size is no page-aligned. */
goto fail;
if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
goto fail;
index = (bio->bi_sector >> 3) + xdev->offset;
bio_for_each_segment(bvec, bio, i) {
page_addr = (unsigned long)
kmap(bvec->bv_page) + bvec->bv_offset;
bytes = bvec->bv_len;
if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
/* More paranoia. */
goto fail;
while (bytes > 0) {
if (bio_data_dir(bio) == READ) {
if (xpram_page_in(page_addr, index) != 0)
goto fail;
} else {
if (xpram_page_out(page_addr, index) != 0)
goto fail;
}
page_addr += 4096;
bytes -= 4096;
index++;
}
}
set_bit(BIO_UPTODATE, &bio->bi_flags);
bio_endio(bio, 0);
return 0;
fail:
bio_io_error(bio);
return 0;
}
static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
unsigned long size;
/*
* get geometry: we have to fake one... trim the size to a
* multiple of 64 (32k): tell we have 16 sectors, 4 heads,
* whatever cylinders. Tell also that data starts at sector. 4.
*/
size = (xpram_pages * 8) & ~0x3f;
geo->cylinders = size >> 6;
geo->heads = 4;
geo->sectors = 16;
geo->start = 4;
return 0;
}
static struct block_device_operations xpram_devops =
{
.owner = THIS_MODULE,
.getgeo = xpram_getgeo,
};
/*
* Setup xpram_sizes array.
*/
static int __init xpram_setup_sizes(unsigned long pages)
{
unsigned long mem_needed;
unsigned long mem_auto;
unsigned long long size;
int mem_auto_no;
int i;
/* Check number of devices. */
if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
PRINT_ERR("invalid number %d of devices\n",devs);
return -EINVAL;
}
xpram_devs = devs;
/*
* Copy sizes array to xpram_sizes and align partition
* sizes to page boundary.
*/
mem_needed = 0;
mem_auto_no = 0;
for (i = 0; i < xpram_devs; i++) {
if (sizes[i]) {
size = simple_strtoull(sizes[i], &sizes[i], 0);
switch (sizes[i][0]) {
case 'g':
case 'G':
size <<= 20;
break;
case 'm':
case 'M':
size <<= 10;
}
xpram_sizes[i] = (size + 3) & -4UL;
}
if (xpram_sizes[i])
mem_needed += xpram_sizes[i];
else
mem_auto_no++;
}
PRINT_INFO(" number of devices (partitions): %d \n", xpram_devs);
for (i = 0; i < xpram_devs; i++) {
if (xpram_sizes[i])
PRINT_INFO(" size of partition %d: %u kB\n",
i, xpram_sizes[i]);
else
PRINT_INFO(" size of partition %d to be set "
"automatically\n",i);
}
PRINT_DEBUG(" memory needed (for sized partitions): %lu kB\n",
mem_needed);
PRINT_DEBUG(" partitions to be sized automatically: %d\n",
mem_auto_no);
if (mem_needed > pages * 4) {
PRINT_ERR("Not enough expanded memory available\n");
return -EINVAL;
}
/*
* partitioning:
* xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
* else: ; all partitions with zero xpram_sizes[i]
* partition equally the remaining space
*/
if (mem_auto_no) {
mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
PRINT_INFO(" automatically determined "
"partition size: %lu kB\n", mem_auto);
for (i = 0; i < xpram_devs; i++)
if (xpram_sizes[i] == 0)
xpram_sizes[i] = mem_auto;
}
return 0;
}
static struct request_queue *xpram_queue;
static int __init xpram_setup_blkdev(void)
{
unsigned long offset;
int i, rc = -ENOMEM;
for (i = 0; i < xpram_devs; i++) {
struct gendisk *disk = alloc_disk(1);
if (!disk)
goto out;
xpram_disks[i] = disk;
}
/*
* Register xpram major.
*/
rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
if (rc < 0)
goto out;
/*
* Assign the other needed values: make request function, sizes and
* hardsect size. All the minor devices feature the same value.
*/
xpram_queue = blk_alloc_queue(GFP_KERNEL);
if (!xpram_queue) {
rc = -ENOMEM;
goto out_unreg;
}
blk_queue_make_request(xpram_queue, xpram_make_request);
blk_queue_hardsect_size(xpram_queue, 4096);
/*
* Setup device structures.
*/
offset = 0;
for (i = 0; i < xpram_devs; i++) {
struct gendisk *disk = xpram_disks[i];
xpram_devices[i].size = xpram_sizes[i] / 4;
xpram_devices[i].offset = offset;
offset += xpram_devices[i].size;
disk->major = XPRAM_MAJOR;
disk->first_minor = i;
disk->fops = &xpram_devops;
disk->private_data = &xpram_devices[i];
disk->queue = xpram_queue;
sprintf(disk->disk_name, "slram%d", i);
set_capacity(disk, xpram_sizes[i] << 1);
add_disk(disk);
}
return 0;
out_unreg:
unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
out:
while (i--)
put_disk(xpram_disks[i]);
return rc;
}
/*
* Finally, the init/exit functions.
*/
static void __exit xpram_exit(void)
{
int i;
for (i = 0; i < xpram_devs; i++) {
del_gendisk(xpram_disks[i]);
put_disk(xpram_disks[i]);
}
unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
blk_cleanup_queue(xpram_queue);
}
static int __init xpram_init(void)
{
int rc;
/* Find out size of expanded memory. */
if (xpram_present() != 0) {
PRINT_WARN("No expanded memory available\n");
return -ENODEV;
}
xpram_pages = xpram_highest_page_index() + 1;
PRINT_INFO(" %u pages expanded memory found (%lu KB).\n",
xpram_pages, (unsigned long) xpram_pages*4);
rc = xpram_setup_sizes(xpram_pages);
if (rc)
return rc;
return xpram_setup_blkdev();
}
module_init(xpram_init);
module_exit(xpram_exit);
