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 #define KMSG_COMPONENT "xpram"
29 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
31 #include <linux/module.h>
32 #include <linux/moduleparam.h>
33 #include <linux/ctype.h> /* isdigit, isxdigit */
34 #include <linux/errno.h>
35 #include <linux/init.h>
36 #include <linux/blkdev.h>
37 #include <linux/blkpg.h>
38 #include <linux/hdreg.h> /* HDIO_GETGEO */
39 #include <linux/device.h>
40 #include <linux/bio.h>
41 #include <linux/suspend.h>
42 #include <linux/platform_device.h>
43 #include <linux/gfp.h>
44 #include <asm/uaccess.h>
46 #define XPRAM_NAME "xpram"
47 #define XPRAM_DEVS 1 /* one partition */
48 #define XPRAM_MAX_DEVS 32 /* maximal number of devices (partitions) */
51 unsigned int size; /* size of xpram segment in pages */
52 unsigned int offset; /* start page of xpram segment */
55 static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
56 static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
57 static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
58 static struct request_queue *xpram_queues[XPRAM_MAX_DEVS];
59 static unsigned int xpram_pages;
60 static int xpram_devs;
63 * Parameter parsing functions.
65 static int devs = XPRAM_DEVS;
66 static char *sizes[XPRAM_MAX_DEVS];
68 module_param(devs, int, 0);
69 module_param_array(sizes, charp, NULL, 0);
71 MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
72 "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
73 MODULE_PARM_DESC(sizes, "list of device (partition) sizes " \
74 "the defaults are 0s \n" \
75 "All devices with size 0 equally partition the "
76 "remaining space on the expanded strorage not "
77 "claimed by explicit sizes\n");
78 MODULE_LICENSE("GPL");
81 * Copy expanded memory page (4kB) into main memory
83 * page_addr: address of target page
84 * xpage_index: index of expandeded memory page
86 * 0: if operation succeeds
87 * -EIO: if pgin failed
88 * -ENXIO: if xpram has vanished
90 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
92 int cc = 2; /* return unused cc 2 if pgin traps */
95 " .insn rre,0xb22e0000,%1,%2\n" /* pgin %1,%2 */
100 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
111 * Copy a 4kB page of main memory to an expanded memory page
113 * page_addr: address of source page
114 * xpage_index: index of expandeded memory page
116 * 0: if operation succeeds
117 * -EIO: if pgout failed
118 * -ENXIO: if xpram has vanished
120 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
122 int cc = 2; /* return unused cc 2 if pgin traps */
125 " .insn rre,0xb22f0000,%1,%2\n" /* pgout %1,%2 */
130 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
141 * Check if xpram is available.
143 static int xpram_present(void)
145 unsigned long mem_page;
148 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
151 rc = xpram_page_in(mem_page, 0);
153 return rc ? -ENXIO : 0;
157 * Return index of the last available xpram page.
159 static unsigned long xpram_highest_page_index(void)
161 unsigned int page_index, add_bit;
162 unsigned long mem_page;
164 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
169 add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
170 while (add_bit > 0) {
171 if (xpram_page_in(mem_page, page_index | add_bit) == 0)
172 page_index |= add_bit;
176 free_page (mem_page);
182 * Block device make request function.
184 static void xpram_make_request(struct request_queue *q, struct bio *bio)
186 xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
188 struct bvec_iter iter;
190 unsigned long page_addr;
193 blk_queue_split(q, &bio, q->bio_split);
195 if ((bio->bi_iter.bi_sector & 7) != 0 ||
196 (bio->bi_iter.bi_size & 4095) != 0)
197 /* Request is not page-aligned. */
199 if ((bio->bi_iter.bi_size >> 12) > xdev->size)
200 /* Request size is no page-aligned. */
202 if ((bio->bi_iter.bi_sector >> 3) > 0xffffffffU - xdev->offset)
204 index = (bio->bi_iter.bi_sector >> 3) + xdev->offset;
205 bio_for_each_segment(bvec, bio, iter) {
206 page_addr = (unsigned long)
207 kmap(bvec.bv_page) + bvec.bv_offset;
209 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
213 if (bio_data_dir(bio) == READ) {
214 if (xpram_page_in(page_addr, index) != 0)
217 if (xpram_page_out(page_addr, index) != 0)
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 const 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;
266 /* Check number of devices. */
267 if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
268 pr_err("%d is not a valid number of XPRAM devices\n",devs);
274 * Copy sizes array to xpram_sizes and align partition
275 * sizes to page boundary.
279 for (i = 0; i < xpram_devs; i++) {
281 size = simple_strtoull(sizes[i], &sizes_end, 0);
282 switch (*sizes_end) {
291 xpram_sizes[i] = (size + 3) & -4UL;
294 mem_needed += xpram_sizes[i];
299 pr_info(" number of devices (partitions): %d \n", xpram_devs);
300 for (i = 0; i < xpram_devs; i++) {
302 pr_info(" size of partition %d: %u kB\n",
305 pr_info(" size of partition %d to be set "
306 "automatically\n",i);
308 pr_info(" memory needed (for sized partitions): %lu kB\n",
310 pr_info(" partitions to be sized automatically: %d\n",
313 if (mem_needed > pages * 4) {
314 pr_err("Not enough expanded memory available\n");
320 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
321 * else: ; all partitions with zero xpram_sizes[i]
322 * partition equally the remaining space
325 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
326 pr_info(" automatically determined "
327 "partition size: %lu kB\n", mem_auto);
328 for (i = 0; i < xpram_devs; i++)
329 if (xpram_sizes[i] == 0)
330 xpram_sizes[i] = mem_auto;
335 static int __init xpram_setup_blkdev(void)
337 unsigned long offset;
340 for (i = 0; i < xpram_devs; i++) {
341 xpram_disks[i] = alloc_disk(1);
344 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
345 if (!xpram_queues[i]) {
346 put_disk(xpram_disks[i]);
349 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, xpram_queues[i]);
350 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
351 blk_queue_make_request(xpram_queues[i], xpram_make_request);
352 blk_queue_logical_block_size(xpram_queues[i], 4096);
356 * Register xpram major.
358 rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
363 * Setup device structures.
366 for (i = 0; i < xpram_devs; i++) {
367 struct gendisk *disk = xpram_disks[i];
369 xpram_devices[i].size = xpram_sizes[i] / 4;
370 xpram_devices[i].offset = offset;
371 offset += xpram_devices[i].size;
372 disk->major = XPRAM_MAJOR;
373 disk->first_minor = i;
374 disk->fops = &xpram_devops;
375 disk->private_data = &xpram_devices[i];
376 disk->queue = xpram_queues[i];
377 sprintf(disk->disk_name, "slram%d", i);
378 set_capacity(disk, xpram_sizes[i] << 1);
385 blk_cleanup_queue(xpram_queues[i]);
386 put_disk(xpram_disks[i]);
392 * Resume failed: Print error message and call panic.
394 static void xpram_resume_error(const char *message)
396 pr_err("Resuming the system failed: %s\n", message);
397 panic("xpram resume error\n");
401 * Check if xpram setup changed between suspend and resume.
403 static int xpram_restore(struct device *dev)
407 if (xpram_present() != 0)
408 xpram_resume_error("xpram disappeared");
409 if (xpram_pages != xpram_highest_page_index() + 1)
410 xpram_resume_error("Size of xpram changed");
414 static const struct dev_pm_ops xpram_pm_ops = {
415 .restore = xpram_restore,
418 static struct platform_driver xpram_pdrv = {
425 static struct platform_device *xpram_pdev;
428 * Finally, the init/exit functions.
430 static void __exit xpram_exit(void)
433 for (i = 0; i < xpram_devs; i++) {
434 del_gendisk(xpram_disks[i]);
435 blk_cleanup_queue(xpram_queues[i]);
436 put_disk(xpram_disks[i]);
438 unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
439 platform_device_unregister(xpram_pdev);
440 platform_driver_unregister(&xpram_pdrv);
443 static int __init xpram_init(void)
447 /* Find out size of expanded memory. */
448 if (xpram_present() != 0) {
449 pr_err("No expanded memory available\n");
452 xpram_pages = xpram_highest_page_index() + 1;
453 pr_info(" %u pages expanded memory found (%lu KB).\n",
454 xpram_pages, (unsigned long) xpram_pages*4);
455 rc = xpram_setup_sizes(xpram_pages);
458 rc = platform_driver_register(&xpram_pdrv);
461 xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
462 if (IS_ERR(xpram_pdev)) {
463 rc = PTR_ERR(xpram_pdev);
464 goto fail_platform_driver_unregister;
466 rc = xpram_setup_blkdev();
468 goto fail_platform_device_unregister;
471 fail_platform_device_unregister:
472 platform_device_unregister(xpram_pdev);
473 fail_platform_driver_unregister:
474 platform_driver_unregister(&xpram_pdrv);
478 module_init(xpram_init);
479 module_exit(xpram_exit);