1 /*
2 * Xpram.c -- the S/390 expanded memory RAM-disk
3 *
4 * significant parts of this code are based on
5 * the sbull device driver presented in
6 * A. Rubini: Linux Device Drivers
7 *
8 * Author of XPRAM specific coding: Reinhard Buendgen
9 * buendgen@de.ibm.com
10 * Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
11 *
12 * External interfaces:
13 * Interfaces to linux kernel
14 * xpram_setup: read kernel parameters
15 * Device specific file operations
16 * xpram_iotcl
17 * xpram_open
18 *
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[])
23 *
24 * Potential future improvements:
25 * generic hard disk support to replace ad-hoc partitioning
26 */
27
28 #define KMSG_COMPONENT "xpram"
29 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
30
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>
45
46 #define XPRAM_NAME "xpram"
47 #define XPRAM_DEVS 1 /* one partition */
48 #define XPRAM_MAX_DEVS 32 /* maximal number of devices (partitions) */
49
50 typedef struct {
51 unsigned int size; /* size of xpram segment in pages */
52 unsigned int offset; /* start page of xpram segment */
53 } xpram_device_t;
54
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;
61
62 /*
63 * Parameter parsing functions.
64 */
65 static int devs = XPRAM_DEVS;
66 static char *sizes[XPRAM_MAX_DEVS];
67
68 module_param(devs, int, 0);
69 module_param_array(sizes, charp, NULL, 0);
70
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");
79
80 /*
81 * Copy expanded memory page (4kB) into main memory
82 * Arguments
83 * page_addr: address of target page
84 * xpage_index: index of expandeded memory page
85 * Return value
86 * 0: if operation succeeds
87 * -EIO: if pgin failed
88 * -ENXIO: if xpram has vanished
89 */
xpram_page_in(unsigned long page_addr,unsigned int xpage_index)90 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
91 {
92 int cc = 2; /* return unused cc 2 if pgin traps */
93
94 asm volatile(
95 " .insn rre,0xb22e0000,%1,%2\n" /* pgin %1,%2 */
96 "0: ipm %0\n"
97 " srl %0,28\n"
98 "1:\n"
99 EX_TABLE(0b,1b)
100 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
101 if (cc == 3)
102 return -ENXIO;
103 if (cc == 2)
104 return -ENXIO;
105 if (cc == 1)
106 return -EIO;
107 return 0;
108 }
109
110 /*
111 * Copy a 4kB page of main memory to an expanded memory page
112 * Arguments
113 * page_addr: address of source page
114 * xpage_index: index of expandeded memory page
115 * Return value
116 * 0: if operation succeeds
117 * -EIO: if pgout failed
118 * -ENXIO: if xpram has vanished
119 */
xpram_page_out(unsigned long page_addr,unsigned int xpage_index)120 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
121 {
122 int cc = 2; /* return unused cc 2 if pgin traps */
123
124 asm volatile(
125 " .insn rre,0xb22f0000,%1,%2\n" /* pgout %1,%2 */
126 "0: ipm %0\n"
127 " srl %0,28\n"
128 "1:\n"
129 EX_TABLE(0b,1b)
130 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
131 if (cc == 3)
132 return -ENXIO;
133 if (cc == 2)
134 return -ENXIO;
135 if (cc == 1)
136 return -EIO;
137 return 0;
138 }
139
140 /*
141 * Check if xpram is available.
142 */
xpram_present(void)143 static int xpram_present(void)
144 {
145 unsigned long mem_page;
146 int rc;
147
148 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
149 if (!mem_page)
150 return -ENOMEM;
151 rc = xpram_page_in(mem_page, 0);
152 free_page(mem_page);
153 return rc ? -ENXIO : 0;
154 }
155
156 /*
157 * Return index of the last available xpram page.
158 */
xpram_highest_page_index(void)159 static unsigned long xpram_highest_page_index(void)
160 {
161 unsigned int page_index, add_bit;
162 unsigned long mem_page;
163
164 mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
165 if (!mem_page)
166 return 0;
167
168 page_index = 0;
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;
173 add_bit >>= 1;
174 }
175
176 free_page (mem_page);
177
178 return page_index;
179 }
180
181 /*
182 * Block device make request function.
183 */
xpram_make_request(struct request_queue * q,struct bio * bio)184 static blk_qc_t xpram_make_request(struct request_queue *q, struct bio *bio)
185 {
186 xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
187 struct bio_vec bvec;
188 struct bvec_iter iter;
189 unsigned int index;
190 unsigned long page_addr;
191 unsigned long bytes;
192
193 blk_queue_split(q, &bio, q->bio_split);
194
195 if ((bio->bi_iter.bi_sector & 7) != 0 ||
196 (bio->bi_iter.bi_size & 4095) != 0)
197 /* Request is not page-aligned. */
198 goto fail;
199 if ((bio->bi_iter.bi_size >> 12) > xdev->size)
200 /* Request size is no page-aligned. */
201 goto fail;
202 if ((bio->bi_iter.bi_sector >> 3) > 0xffffffffU - xdev->offset)
203 goto fail;
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;
208 bytes = bvec.bv_len;
209 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
210 /* More paranoia. */
211 goto fail;
212 while (bytes > 0) {
213 if (bio_data_dir(bio) == READ) {
214 if (xpram_page_in(page_addr, index) != 0)
215 goto fail;
216 } else {
217 if (xpram_page_out(page_addr, index) != 0)
218 goto fail;
219 }
220 page_addr += 4096;
221 bytes -= 4096;
222 index++;
223 }
224 }
225 bio_endio(bio);
226 return BLK_QC_T_NONE;
227 fail:
228 bio_io_error(bio);
229 return BLK_QC_T_NONE;
230 }
231
xpram_getgeo(struct block_device * bdev,struct hd_geometry * geo)232 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
233 {
234 unsigned long size;
235
236 /*
237 * get geometry: we have to fake one... trim the size to a
238 * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
239 * whatever cylinders. Tell also that data starts at sector. 4.
240 */
241 size = (xpram_pages * 8) & ~0x3f;
242 geo->cylinders = size >> 6;
243 geo->heads = 4;
244 geo->sectors = 16;
245 geo->start = 4;
246 return 0;
247 }
248
249 static const struct block_device_operations xpram_devops =
250 {
251 .owner = THIS_MODULE,
252 .getgeo = xpram_getgeo,
253 };
254
255 /*
256 * Setup xpram_sizes array.
257 */
xpram_setup_sizes(unsigned long pages)258 static int __init xpram_setup_sizes(unsigned long pages)
259 {
260 unsigned long mem_needed;
261 unsigned long mem_auto;
262 unsigned long long size;
263 char *sizes_end;
264 int mem_auto_no;
265 int i;
266
267 /* Check number of devices. */
268 if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
269 pr_err("%d is not a valid number of XPRAM devices\n",devs);
270 return -EINVAL;
271 }
272 xpram_devs = devs;
273
274 /*
275 * Copy sizes array to xpram_sizes and align partition
276 * sizes to page boundary.
277 */
278 mem_needed = 0;
279 mem_auto_no = 0;
280 for (i = 0; i < xpram_devs; i++) {
281 if (sizes[i]) {
282 size = simple_strtoull(sizes[i], &sizes_end, 0);
283 switch (*sizes_end) {
284 case 'g':
285 case 'G':
286 size <<= 20;
287 break;
288 case 'm':
289 case 'M':
290 size <<= 10;
291 }
292 xpram_sizes[i] = (size + 3) & -4UL;
293 }
294 if (xpram_sizes[i])
295 mem_needed += xpram_sizes[i];
296 else
297 mem_auto_no++;
298 }
299
300 pr_info(" number of devices (partitions): %d \n", xpram_devs);
301 for (i = 0; i < xpram_devs; i++) {
302 if (xpram_sizes[i])
303 pr_info(" size of partition %d: %u kB\n",
304 i, xpram_sizes[i]);
305 else
306 pr_info(" size of partition %d to be set "
307 "automatically\n",i);
308 }
309 pr_info(" memory needed (for sized partitions): %lu kB\n",
310 mem_needed);
311 pr_info(" partitions to be sized automatically: %d\n",
312 mem_auto_no);
313
314 if (mem_needed > pages * 4) {
315 pr_err("Not enough expanded memory available\n");
316 return -EINVAL;
317 }
318
319 /*
320 * partitioning:
321 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
322 * else: ; all partitions with zero xpram_sizes[i]
323 * partition equally the remaining space
324 */
325 if (mem_auto_no) {
326 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
327 pr_info(" automatically determined "
328 "partition size: %lu kB\n", mem_auto);
329 for (i = 0; i < xpram_devs; i++)
330 if (xpram_sizes[i] == 0)
331 xpram_sizes[i] = mem_auto;
332 }
333 return 0;
334 }
335
xpram_setup_blkdev(void)336 static int __init xpram_setup_blkdev(void)
337 {
338 unsigned long offset;
339 int i, rc = -ENOMEM;
340
341 for (i = 0; i < xpram_devs; i++) {
342 xpram_disks[i] = alloc_disk(1);
343 if (!xpram_disks[i])
344 goto out;
345 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
346 if (!xpram_queues[i]) {
347 put_disk(xpram_disks[i]);
348 goto out;
349 }
350 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, xpram_queues[i]);
351 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
352 blk_queue_make_request(xpram_queues[i], xpram_make_request);
353 blk_queue_logical_block_size(xpram_queues[i], 4096);
354 }
355
356 /*
357 * Register xpram major.
358 */
359 rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
360 if (rc < 0)
361 goto out;
362
363 /*
364 * Setup device structures.
365 */
366 offset = 0;
367 for (i = 0; i < xpram_devs; i++) {
368 struct gendisk *disk = xpram_disks[i];
369
370 xpram_devices[i].size = xpram_sizes[i] / 4;
371 xpram_devices[i].offset = offset;
372 offset += xpram_devices[i].size;
373 disk->major = XPRAM_MAJOR;
374 disk->first_minor = i;
375 disk->fops = &xpram_devops;
376 disk->private_data = &xpram_devices[i];
377 disk->queue = xpram_queues[i];
378 sprintf(disk->disk_name, "slram%d", i);
379 set_capacity(disk, xpram_sizes[i] << 1);
380 add_disk(disk);
381 }
382
383 return 0;
384 out:
385 while (i--) {
386 blk_cleanup_queue(xpram_queues[i]);
387 put_disk(xpram_disks[i]);
388 }
389 return rc;
390 }
391
392 /*
393 * Resume failed: Print error message and call panic.
394 */
xpram_resume_error(const char * message)395 static void xpram_resume_error(const char *message)
396 {
397 pr_err("Resuming the system failed: %s\n", message);
398 panic("xpram resume error\n");
399 }
400
401 /*
402 * Check if xpram setup changed between suspend and resume.
403 */
xpram_restore(struct device * dev)404 static int xpram_restore(struct device *dev)
405 {
406 if (!xpram_pages)
407 return 0;
408 if (xpram_present() != 0)
409 xpram_resume_error("xpram disappeared");
410 if (xpram_pages != xpram_highest_page_index() + 1)
411 xpram_resume_error("Size of xpram changed");
412 return 0;
413 }
414
415 static const struct dev_pm_ops xpram_pm_ops = {
416 .restore = xpram_restore,
417 };
418
419 static struct platform_driver xpram_pdrv = {
420 .driver = {
421 .name = XPRAM_NAME,
422 .pm = &xpram_pm_ops,
423 },
424 };
425
426 static struct platform_device *xpram_pdev;
427
428 /*
429 * Finally, the init/exit functions.
430 */
xpram_exit(void)431 static void __exit xpram_exit(void)
432 {
433 int i;
434 for (i = 0; i < xpram_devs; i++) {
435 del_gendisk(xpram_disks[i]);
436 blk_cleanup_queue(xpram_queues[i]);
437 put_disk(xpram_disks[i]);
438 }
439 unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
440 platform_device_unregister(xpram_pdev);
441 platform_driver_unregister(&xpram_pdrv);
442 }
443
xpram_init(void)444 static int __init xpram_init(void)
445 {
446 int rc;
447
448 /* Find out size of expanded memory. */
449 if (xpram_present() != 0) {
450 pr_err("No expanded memory available\n");
451 return -ENODEV;
452 }
453 xpram_pages = xpram_highest_page_index() + 1;
454 pr_info(" %u pages expanded memory found (%lu KB).\n",
455 xpram_pages, (unsigned long) xpram_pages*4);
456 rc = xpram_setup_sizes(xpram_pages);
457 if (rc)
458 return rc;
459 rc = platform_driver_register(&xpram_pdrv);
460 if (rc)
461 return rc;
462 xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
463 if (IS_ERR(xpram_pdev)) {
464 rc = PTR_ERR(xpram_pdev);
465 goto fail_platform_driver_unregister;
466 }
467 rc = xpram_setup_blkdev();
468 if (rc)
469 goto fail_platform_device_unregister;
470 return 0;
471
472 fail_platform_device_unregister:
473 platform_device_unregister(xpram_pdev);
474 fail_platform_driver_unregister:
475 platform_driver_unregister(&xpram_pdrv);
476 return rc;
477 }
478
479 module_init(xpram_init);
480 module_exit(xpram_exit);
481