1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Xpram.c -- the S/390 expanded memory RAM-disk
4 *
5 * significant parts of this code are based on
6 * the sbull device driver presented in
7 * A. Rubini: Linux Device Drivers
8 *
9 * Author of XPRAM specific coding: Reinhard Buendgen
10 * buendgen@de.ibm.com
11 * Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
12 *
13 * External interfaces:
14 * Interfaces to linux kernel
15 * xpram_setup: read kernel parameters
16 * Device specific file operations
17 * xpram_iotcl
18 * xpram_open
19 *
20 * "ad-hoc" partitioning:
21 * the expanded memory can be partitioned among several devices
22 * (with different minors). The partitioning set up can be
23 * set by kernel or module parameters (int devs & int sizes[])
24 *
25 * Potential future improvements:
26 * generic hard disk support to replace ad-hoc partitioning
27 */
28
29 #define KMSG_COMPONENT "xpram"
30 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
31
32 #include <linux/module.h>
33 #include <linux/moduleparam.h>
34 #include <linux/ctype.h> /* isdigit, isxdigit */
35 #include <linux/errno.h>
36 #include <linux/init.h>
37 #include <linux/blkdev.h>
38 #include <linux/blkpg.h>
39 #include <linux/hdreg.h> /* HDIO_GETGEO */
40 #include <linux/device.h>
41 #include <linux/bio.h>
42 #include <linux/suspend.h>
43 #include <linux/platform_device.h>
44 #include <linux/gfp.h>
45 #include <linux/uaccess.h>
46
47 #define XPRAM_NAME "xpram"
48 #define XPRAM_DEVS 1 /* one partition */
49 #define XPRAM_MAX_DEVS 32 /* maximal number of devices (partitions) */
50
51 typedef struct {
52 unsigned int size; /* size of xpram segment in pages */
53 unsigned int offset; /* start page of xpram segment */
54 } xpram_device_t;
55
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;
62
63 /*
64 * Parameter parsing functions.
65 */
66 static int devs = XPRAM_DEVS;
67 static char *sizes[XPRAM_MAX_DEVS];
68
69 module_param(devs, int, 0);
70 module_param_array(sizes, charp, NULL, 0);
71
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");
80
81 /*
82 * Copy expanded memory page (4kB) into main memory
83 * Arguments
84 * page_addr: address of target page
85 * xpage_index: index of expandeded memory page
86 * Return value
87 * 0: if operation succeeds
88 * -EIO: if pgin failed
89 * -ENXIO: if xpram has vanished
90 */
xpram_page_in(unsigned long page_addr,unsigned int xpage_index)91 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
92 {
93 int cc = 2; /* return unused cc 2 if pgin traps */
94
95 asm volatile(
96 " .insn rre,0xb22e0000,%1,%2\n" /* pgin %1,%2 */
97 "0: ipm %0\n"
98 " srl %0,28\n"
99 "1:\n"
100 EX_TABLE(0b,1b)
101 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
102 if (cc == 3)
103 return -ENXIO;
104 if (cc == 2)
105 return -ENXIO;
106 if (cc == 1)
107 return -EIO;
108 return 0;
109 }
110
111 /*
112 * Copy a 4kB page of main memory to an expanded memory page
113 * Arguments
114 * page_addr: address of source page
115 * xpage_index: index of expandeded memory page
116 * Return value
117 * 0: if operation succeeds
118 * -EIO: if pgout failed
119 * -ENXIO: if xpram has vanished
120 */
xpram_page_out(unsigned long page_addr,unsigned int xpage_index)121 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
122 {
123 int cc = 2; /* return unused cc 2 if pgin traps */
124
125 asm volatile(
126 " .insn rre,0xb22f0000,%1,%2\n" /* pgout %1,%2 */
127 "0: ipm %0\n"
128 " srl %0,28\n"
129 "1:\n"
130 EX_TABLE(0b,1b)
131 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
132 if (cc == 3)
133 return -ENXIO;
134 if (cc == 2)
135 return -ENXIO;
136 if (cc == 1)
137 return -EIO;
138 return 0;
139 }
140
141 /*
142 * Check if xpram is available.
143 */
xpram_present(void)144 static int xpram_present(void)
145 {
146 unsigned long mem_page;
147 int rc;
148
149 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
150 if (!mem_page)
151 return -ENOMEM;
152 rc = xpram_page_in(mem_page, 0);
153 free_page(mem_page);
154 return rc ? -ENXIO : 0;
155 }
156
157 /*
158 * Return index of the last available xpram page.
159 */
xpram_highest_page_index(void)160 static unsigned long xpram_highest_page_index(void)
161 {
162 unsigned int page_index, add_bit;
163 unsigned long mem_page;
164
165 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
166 if (!mem_page)
167 return 0;
168
169 page_index = 0;
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;
174 add_bit >>= 1;
175 }
176
177 free_page (mem_page);
178
179 return page_index;
180 }
181
182 /*
183 * Block device make request function.
184 */
xpram_make_request(struct request_queue * q,struct bio * bio)185 static blk_qc_t xpram_make_request(struct request_queue *q, struct bio *bio)
186 {
187 xpram_device_t *xdev = bio->bi_disk->private_data;
188 struct bio_vec bvec;
189 struct bvec_iter iter;
190 unsigned int index;
191 unsigned long page_addr;
192 unsigned long bytes;
193
194 blk_queue_split(q, &bio);
195
196 if ((bio->bi_iter.bi_sector & 7) != 0 ||
197 (bio->bi_iter.bi_size & 4095) != 0)
198 /* Request is not page-aligned. */
199 goto fail;
200 if ((bio->bi_iter.bi_size >> 12) > xdev->size)
201 /* Request size is no page-aligned. */
202 goto fail;
203 if ((bio->bi_iter.bi_sector >> 3) > 0xffffffffU - xdev->offset)
204 goto fail;
205 index = (bio->bi_iter.bi_sector >> 3) + xdev->offset;
206 bio_for_each_segment(bvec, bio, iter) {
207 page_addr = (unsigned long)
208 kmap(bvec.bv_page) + bvec.bv_offset;
209 bytes = bvec.bv_len;
210 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
211 /* More paranoia. */
212 goto fail;
213 while (bytes > 0) {
214 if (bio_data_dir(bio) == READ) {
215 if (xpram_page_in(page_addr, index) != 0)
216 goto fail;
217 } else {
218 if (xpram_page_out(page_addr, index) != 0)
219 goto fail;
220 }
221 page_addr += 4096;
222 bytes -= 4096;
223 index++;
224 }
225 }
226 bio_endio(bio);
227 return BLK_QC_T_NONE;
228 fail:
229 bio_io_error(bio);
230 return BLK_QC_T_NONE;
231 }
232
xpram_getgeo(struct block_device * bdev,struct hd_geometry * geo)233 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
234 {
235 unsigned long size;
236
237 /*
238 * get geometry: we have to fake one... trim the size to a
239 * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
240 * whatever cylinders. Tell also that data starts at sector. 4.
241 */
242 size = (xpram_pages * 8) & ~0x3f;
243 geo->cylinders = size >> 6;
244 geo->heads = 4;
245 geo->sectors = 16;
246 geo->start = 4;
247 return 0;
248 }
249
250 static const struct block_device_operations xpram_devops =
251 {
252 .owner = THIS_MODULE,
253 .getgeo = xpram_getgeo,
254 };
255
256 /*
257 * Setup xpram_sizes array.
258 */
xpram_setup_sizes(unsigned long pages)259 static int __init xpram_setup_sizes(unsigned long pages)
260 {
261 unsigned long mem_needed;
262 unsigned long mem_auto;
263 unsigned long long size;
264 char *sizes_end;
265 int mem_auto_no;
266 int i;
267
268 /* Check number of devices. */
269 if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
270 pr_err("%d is not a valid number of XPRAM devices\n",devs);
271 return -EINVAL;
272 }
273 xpram_devs = devs;
274
275 /*
276 * Copy sizes array to xpram_sizes and align partition
277 * sizes to page boundary.
278 */
279 mem_needed = 0;
280 mem_auto_no = 0;
281 for (i = 0; i < xpram_devs; i++) {
282 if (sizes[i]) {
283 size = simple_strtoull(sizes[i], &sizes_end, 0);
284 switch (*sizes_end) {
285 case 'g':
286 case 'G':
287 size <<= 20;
288 break;
289 case 'm':
290 case 'M':
291 size <<= 10;
292 }
293 xpram_sizes[i] = (size + 3) & -4UL;
294 }
295 if (xpram_sizes[i])
296 mem_needed += xpram_sizes[i];
297 else
298 mem_auto_no++;
299 }
300
301 pr_info(" number of devices (partitions): %d \n", xpram_devs);
302 for (i = 0; i < xpram_devs; i++) {
303 if (xpram_sizes[i])
304 pr_info(" size of partition %d: %u kB\n",
305 i, xpram_sizes[i]);
306 else
307 pr_info(" size of partition %d to be set "
308 "automatically\n",i);
309 }
310 pr_info(" memory needed (for sized partitions): %lu kB\n",
311 mem_needed);
312 pr_info(" partitions to be sized automatically: %d\n",
313 mem_auto_no);
314
315 if (mem_needed > pages * 4) {
316 pr_err("Not enough expanded memory available\n");
317 return -EINVAL;
318 }
319
320 /*
321 * partitioning:
322 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
323 * else: ; all partitions with zero xpram_sizes[i]
324 * partition equally the remaining space
325 */
326 if (mem_auto_no) {
327 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
328 pr_info(" automatically determined "
329 "partition size: %lu kB\n", mem_auto);
330 for (i = 0; i < xpram_devs; i++)
331 if (xpram_sizes[i] == 0)
332 xpram_sizes[i] = mem_auto;
333 }
334 return 0;
335 }
336
xpram_setup_blkdev(void)337 static int __init xpram_setup_blkdev(void)
338 {
339 unsigned long offset;
340 int i, rc = -ENOMEM;
341
342 for (i = 0; i < xpram_devs; i++) {
343 xpram_disks[i] = alloc_disk(1);
344 if (!xpram_disks[i])
345 goto out;
346 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
347 if (!xpram_queues[i]) {
348 put_disk(xpram_disks[i]);
349 goto out;
350 }
351 blk_queue_flag_set(QUEUE_FLAG_NONROT, xpram_queues[i]);
352 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
353 blk_queue_make_request(xpram_queues[i], xpram_make_request);
354 blk_queue_logical_block_size(xpram_queues[i], 4096);
355 }
356
357 /*
358 * Register xpram major.
359 */
360 rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
361 if (rc < 0)
362 goto out;
363
364 /*
365 * Setup device structures.
366 */
367 offset = 0;
368 for (i = 0; i < xpram_devs; i++) {
369 struct gendisk *disk = xpram_disks[i];
370
371 xpram_devices[i].size = xpram_sizes[i] / 4;
372 xpram_devices[i].offset = offset;
373 offset += xpram_devices[i].size;
374 disk->major = XPRAM_MAJOR;
375 disk->first_minor = i;
376 disk->fops = &xpram_devops;
377 disk->private_data = &xpram_devices[i];
378 disk->queue = xpram_queues[i];
379 sprintf(disk->disk_name, "slram%d", i);
380 set_capacity(disk, xpram_sizes[i] << 1);
381 add_disk(disk);
382 }
383
384 return 0;
385 out:
386 while (i--) {
387 blk_cleanup_queue(xpram_queues[i]);
388 put_disk(xpram_disks[i]);
389 }
390 return rc;
391 }
392
393 /*
394 * Resume failed: Print error message and call panic.
395 */
xpram_resume_error(const char * message)396 static void xpram_resume_error(const char *message)
397 {
398 pr_err("Resuming the system failed: %s\n", message);
399 panic("xpram resume error\n");
400 }
401
402 /*
403 * Check if xpram setup changed between suspend and resume.
404 */
xpram_restore(struct device * dev)405 static int xpram_restore(struct device *dev)
406 {
407 if (!xpram_pages)
408 return 0;
409 if (xpram_present() != 0)
410 xpram_resume_error("xpram disappeared");
411 if (xpram_pages != xpram_highest_page_index() + 1)
412 xpram_resume_error("Size of xpram changed");
413 return 0;
414 }
415
416 static const struct dev_pm_ops xpram_pm_ops = {
417 .restore = xpram_restore,
418 };
419
420 static struct platform_driver xpram_pdrv = {
421 .driver = {
422 .name = XPRAM_NAME,
423 .pm = &xpram_pm_ops,
424 },
425 };
426
427 static struct platform_device *xpram_pdev;
428
429 /*
430 * Finally, the init/exit functions.
431 */
xpram_exit(void)432 static void __exit xpram_exit(void)
433 {
434 int i;
435 for (i = 0; i < xpram_devs; i++) {
436 del_gendisk(xpram_disks[i]);
437 blk_cleanup_queue(xpram_queues[i]);
438 put_disk(xpram_disks[i]);
439 }
440 unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
441 platform_device_unregister(xpram_pdev);
442 platform_driver_unregister(&xpram_pdrv);
443 }
444
xpram_init(void)445 static int __init xpram_init(void)
446 {
447 int rc;
448
449 /* Find out size of expanded memory. */
450 if (xpram_present() != 0) {
451 pr_err("No expanded memory available\n");
452 return -ENODEV;
453 }
454 xpram_pages = xpram_highest_page_index() + 1;
455 pr_info(" %u pages expanded memory found (%lu KB).\n",
456 xpram_pages, (unsigned long) xpram_pages*4);
457 rc = xpram_setup_sizes(xpram_pages);
458 if (rc)
459 return rc;
460 rc = platform_driver_register(&xpram_pdrv);
461 if (rc)
462 return rc;
463 xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
464 if (IS_ERR(xpram_pdev)) {
465 rc = PTR_ERR(xpram_pdev);
466 goto fail_platform_driver_unregister;
467 }
468 rc = xpram_setup_blkdev();
469 if (rc)
470 goto fail_platform_device_unregister;
471 return 0;
472
473 fail_platform_device_unregister:
474 platform_device_unregister(xpram_pdev);
475 fail_platform_driver_unregister:
476 platform_driver_unregister(&xpram_pdrv);
477 return rc;
478 }
479
480 module_init(xpram_init);
481 module_exit(xpram_exit);
482