2 * Xpram.c -- the S/390 expanded memory RAM-disk
4 * significant parts of this code are based on
5 * the sbull device driver presented in
6 * A. Rubini: Linux Device Drivers
8 * Author of XPRAM specific coding: Reinhard Buendgen
10 * Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
12 * External interfaces:
13 * Interfaces to linux kernel
14 * xpram_setup: read kernel parameters
15 * Device specific file operations
19 * "ad-hoc" partitioning:
20 * the expanded memory can be partitioned among several devices
21 * (with different minors). The partitioning set up can be
22 * set by kernel or module parameters (int devs & int sizes[])
24 * Potential future improvements:
25 * generic hard disk support to replace ad-hoc partitioning
28 #include <linux/module.h>
29 #include <linux/moduleparam.h>
30 #include <linux/ctype.h> /* isdigit, isxdigit */
31 #include <linux/errno.h>
32 #include <linux/init.h>
33 #include <linux/slab.h>
34 #include <linux/blkdev.h>
35 #include <linux/blkpg.h>
36 #include <linux/hdreg.h> /* HDIO_GETGEO */
37 #include <linux/sysdev.h>
38 #include <linux/bio.h>
39 #include <asm/uaccess.h>
41 #define XPRAM_NAME "xpram"
42 #define XPRAM_DEVS 1 /* one partition */
43 #define XPRAM_MAX_DEVS 32 /* maximal number of devices (partitions) */
45 #define PRINT_DEBUG(x...) printk(KERN_DEBUG XPRAM_NAME " debug:" x)
46 #define PRINT_INFO(x...) printk(KERN_INFO XPRAM_NAME " info:" x)
47 #define PRINT_WARN(x...) printk(KERN_WARNING XPRAM_NAME " warning:" x)
48 #define PRINT_ERR(x...) printk(KERN_ERR XPRAM_NAME " error:" x)
52 unsigned int size; /* size of xpram segment in pages */
53 unsigned int offset; /* start page of xpram segment */
56 static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
57 static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
58 static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
59 static struct request_queue *xpram_queues[XPRAM_MAX_DEVS];
60 static unsigned int xpram_pages;
61 static int xpram_devs;
64 * Parameter parsing functions.
66 static int __initdata devs = XPRAM_DEVS;
67 static char __initdata *sizes[XPRAM_MAX_DEVS];
69 module_param(devs, int, 0);
70 module_param_array(sizes, charp, NULL, 0);
72 MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
73 "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
74 MODULE_PARM_DESC(sizes, "list of device (partition) sizes " \
75 "the defaults are 0s \n" \
76 "All devices with size 0 equally partition the "
77 "remaining space on the expanded strorage not "
78 "claimed by explicit sizes\n");
79 MODULE_LICENSE("GPL");
82 * Copy expanded memory page (4kB) into main memory
84 * page_addr: address of target page
85 * xpage_index: index of expandeded memory page
87 * 0: if operation succeeds
88 * -EIO: if pgin failed
89 * -ENXIO: if xpram has vanished
91 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
93 int cc = 2; /* return unused cc 2 if pgin traps */
96 " .insn rre,0xb22e0000,%1,%2\n" /* pgin %1,%2 */
101 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
112 * Copy a 4kB page of main memory to an expanded memory page
114 * page_addr: address of source page
115 * xpage_index: index of expandeded memory page
117 * 0: if operation succeeds
118 * -EIO: if pgout failed
119 * -ENXIO: if xpram has vanished
121 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
123 int cc = 2; /* return unused cc 2 if pgin traps */
126 " .insn rre,0xb22f0000,%1,%2\n" /* pgout %1,%2 */
131 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
142 * Check if xpram is available.
144 static int __init xpram_present(void)
146 unsigned long mem_page;
149 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
152 rc = xpram_page_in(mem_page, 0);
154 return rc ? -ENXIO : 0;
158 * Return index of the last available xpram page.
160 static unsigned long __init xpram_highest_page_index(void)
162 unsigned int page_index, add_bit;
163 unsigned long mem_page;
165 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
170 add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
171 while (add_bit > 0) {
172 if (xpram_page_in(mem_page, page_index | add_bit) == 0)
173 page_index |= add_bit;
177 free_page (mem_page);
183 * Block device make request function.
185 static int xpram_make_request(struct request_queue *q, struct bio *bio)
187 xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
188 struct bio_vec *bvec;
190 unsigned long page_addr;
194 if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
195 /* Request is not page-aligned. */
197 if ((bio->bi_size >> 12) > xdev->size)
198 /* Request size is no page-aligned. */
200 if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
202 index = (bio->bi_sector >> 3) + xdev->offset;
203 bio_for_each_segment(bvec, bio, i) {
204 page_addr = (unsigned long)
205 kmap(bvec->bv_page) + bvec->bv_offset;
206 bytes = bvec->bv_len;
207 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
211 if (bio_data_dir(bio) == READ) {
212 if (xpram_page_in(page_addr, index) != 0)
215 if (xpram_page_out(page_addr, index) != 0)
223 set_bit(BIO_UPTODATE, &bio->bi_flags);
231 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
236 * get geometry: we have to fake one... trim the size to a
237 * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
238 * whatever cylinders. Tell also that data starts at sector. 4.
240 size = (xpram_pages * 8) & ~0x3f;
241 geo->cylinders = size >> 6;
248 static struct block_device_operations xpram_devops =
250 .owner = THIS_MODULE,
251 .getgeo = xpram_getgeo,
255 * Setup xpram_sizes array.
257 static int __init xpram_setup_sizes(unsigned long pages)
259 unsigned long mem_needed;
260 unsigned long mem_auto;
261 unsigned long long size;
265 /* Check number of devices. */
266 if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
267 PRINT_ERR("invalid number %d of devices\n",devs);
273 * Copy sizes array to xpram_sizes and align partition
274 * sizes to page boundary.
278 for (i = 0; i < xpram_devs; i++) {
280 size = simple_strtoull(sizes[i], &sizes[i], 0);
281 switch (sizes[i][0]) {
290 xpram_sizes[i] = (size + 3) & -4UL;
293 mem_needed += xpram_sizes[i];
298 PRINT_INFO(" number of devices (partitions): %d \n", xpram_devs);
299 for (i = 0; i < xpram_devs; i++) {
301 PRINT_INFO(" size of partition %d: %u kB\n",
304 PRINT_INFO(" size of partition %d to be set "
305 "automatically\n",i);
307 PRINT_DEBUG(" memory needed (for sized partitions): %lu kB\n",
309 PRINT_DEBUG(" partitions to be sized automatically: %d\n",
312 if (mem_needed > pages * 4) {
313 PRINT_ERR("Not enough expanded memory available\n");
319 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
320 * else: ; all partitions with zero xpram_sizes[i]
321 * partition equally the remaining space
324 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
325 PRINT_INFO(" automatically determined "
326 "partition size: %lu kB\n", mem_auto);
327 for (i = 0; i < xpram_devs; i++)
328 if (xpram_sizes[i] == 0)
329 xpram_sizes[i] = mem_auto;
334 static int __init xpram_setup_blkdev(void)
336 unsigned long offset;
339 for (i = 0; i < xpram_devs; i++) {
340 xpram_disks[i] = alloc_disk(1);
343 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
344 if (!xpram_queues[i]) {
345 put_disk(xpram_disks[i]);
348 blk_queue_make_request(xpram_queues[i], xpram_make_request);
349 blk_queue_hardsect_size(xpram_queues[i], 4096);
353 * Register xpram major.
355 rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
360 * Setup device structures.
363 for (i = 0; i < xpram_devs; i++) {
364 struct gendisk *disk = xpram_disks[i];
366 xpram_devices[i].size = xpram_sizes[i] / 4;
367 xpram_devices[i].offset = offset;
368 offset += xpram_devices[i].size;
369 disk->major = XPRAM_MAJOR;
370 disk->first_minor = i;
371 disk->fops = &xpram_devops;
372 disk->private_data = &xpram_devices[i];
373 disk->queue = xpram_queues[i];
374 sprintf(disk->disk_name, "slram%d", i);
375 set_capacity(disk, xpram_sizes[i] << 1);
382 blk_cleanup_queue(xpram_queues[i]);
383 put_disk(xpram_disks[i]);
389 * Finally, the init/exit functions.
391 static void __exit xpram_exit(void)
394 for (i = 0; i < xpram_devs; i++) {
395 del_gendisk(xpram_disks[i]);
396 blk_cleanup_queue(xpram_queues[i]);
397 put_disk(xpram_disks[i]);
399 unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
402 static int __init xpram_init(void)
406 /* Find out size of expanded memory. */
407 if (xpram_present() != 0) {
408 PRINT_WARN("No expanded memory available\n");
411 xpram_pages = xpram_highest_page_index() + 1;
412 PRINT_INFO(" %u pages expanded memory found (%lu KB).\n",
413 xpram_pages, (unsigned long) xpram_pages*4);
414 rc = xpram_setup_sizes(xpram_pages);
417 return xpram_setup_blkdev();
420 module_init(xpram_init);
421 module_exit(xpram_exit);