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xpram.c
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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  * [email protected]
10  * Rewrite for 2.5: Martin Schwidefsky <[email protected]>
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  */
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  */
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  */
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  */
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  */
184 static void 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  unsigned int index;
189  unsigned long page_addr;
190  unsigned long bytes;
191  int i;
192 
193  if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
194  /* Request is not page-aligned. */
195  goto fail;
196  if ((bio->bi_size >> 12) > xdev->size)
197  /* Request size is no page-aligned. */
198  goto fail;
199  if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
200  goto fail;
201  index = (bio->bi_sector >> 3) + xdev->offset;
202  bio_for_each_segment(bvec, bio, i) {
203  page_addr = (unsigned long)
204  kmap(bvec->bv_page) + bvec->bv_offset;
205  bytes = bvec->bv_len;
206  if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
207  /* More paranoia. */
208  goto fail;
209  while (bytes > 0) {
210  if (bio_data_dir(bio) == READ) {
211  if (xpram_page_in(page_addr, index) != 0)
212  goto fail;
213  } else {
214  if (xpram_page_out(page_addr, index) != 0)
215  goto fail;
216  }
217  page_addr += 4096;
218  bytes -= 4096;
219  index++;
220  }
221  }
222  set_bit(BIO_UPTODATE, &bio->bi_flags);
223  bio_endio(bio, 0);
224  return;
225 fail:
226  bio_io_error(bio);
227 }
228 
229 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
230 {
231  unsigned long size;
232 
233  /*
234  * get geometry: we have to fake one... trim the size to a
235  * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
236  * whatever cylinders. Tell also that data starts at sector. 4.
237  */
238  size = (xpram_pages * 8) & ~0x3f;
239  geo->cylinders = size >> 6;
240  geo->heads = 4;
241  geo->sectors = 16;
242  geo->start = 4;
243  return 0;
244 }
245 
246 static const struct block_device_operations xpram_devops =
247 {
248  .owner = THIS_MODULE,
249  .getgeo = xpram_getgeo,
250 };
251 
252 /*
253  * Setup xpram_sizes array.
254  */
255 static int __init xpram_setup_sizes(unsigned long pages)
256 {
257  unsigned long mem_needed;
258  unsigned long mem_auto;
259  unsigned long long size;
260  int mem_auto_no;
261  int i;
262 
263  /* Check number of devices. */
264  if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
265  pr_err("%d is not a valid number of XPRAM devices\n",devs);
266  return -EINVAL;
267  }
268  xpram_devs = devs;
269 
270  /*
271  * Copy sizes array to xpram_sizes and align partition
272  * sizes to page boundary.
273  */
274  mem_needed = 0;
275  mem_auto_no = 0;
276  for (i = 0; i < xpram_devs; i++) {
277  if (sizes[i]) {
278  size = simple_strtoull(sizes[i], &sizes[i], 0);
279  switch (sizes[i][0]) {
280  case 'g':
281  case 'G':
282  size <<= 20;
283  break;
284  case 'm':
285  case 'M':
286  size <<= 10;
287  }
288  xpram_sizes[i] = (size + 3) & -4UL;
289  }
290  if (xpram_sizes[i])
291  mem_needed += xpram_sizes[i];
292  else
293  mem_auto_no++;
294  }
295 
296  pr_info(" number of devices (partitions): %d \n", xpram_devs);
297  for (i = 0; i < xpram_devs; i++) {
298  if (xpram_sizes[i])
299  pr_info(" size of partition %d: %u kB\n",
300  i, xpram_sizes[i]);
301  else
302  pr_info(" size of partition %d to be set "
303  "automatically\n",i);
304  }
305  pr_info(" memory needed (for sized partitions): %lu kB\n",
306  mem_needed);
307  pr_info(" partitions to be sized automatically: %d\n",
308  mem_auto_no);
309 
310  if (mem_needed > pages * 4) {
311  pr_err("Not enough expanded memory available\n");
312  return -EINVAL;
313  }
314 
315  /*
316  * partitioning:
317  * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
318  * else: ; all partitions with zero xpram_sizes[i]
319  * partition equally the remaining space
320  */
321  if (mem_auto_no) {
322  mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
323  pr_info(" automatically determined "
324  "partition size: %lu kB\n", mem_auto);
325  for (i = 0; i < xpram_devs; i++)
326  if (xpram_sizes[i] == 0)
327  xpram_sizes[i] = mem_auto;
328  }
329  return 0;
330 }
331 
332 static int __init xpram_setup_blkdev(void)
333 {
334  unsigned long offset;
335  int i, rc = -ENOMEM;
336 
337  for (i = 0; i < xpram_devs; i++) {
338  xpram_disks[i] = alloc_disk(1);
339  if (!xpram_disks[i])
340  goto out;
341  xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
342  if (!xpram_queues[i]) {
343  put_disk(xpram_disks[i]);
344  goto out;
345  }
346  blk_queue_make_request(xpram_queues[i], xpram_make_request);
347  blk_queue_logical_block_size(xpram_queues[i], 4096);
348  }
349 
350  /*
351  * Register xpram major.
352  */
353  rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
354  if (rc < 0)
355  goto out;
356 
357  /*
358  * Setup device structures.
359  */
360  offset = 0;
361  for (i = 0; i < xpram_devs; i++) {
362  struct gendisk *disk = xpram_disks[i];
363 
364  xpram_devices[i].size = xpram_sizes[i] / 4;
365  xpram_devices[i].offset = offset;
366  offset += xpram_devices[i].size;
367  disk->major = XPRAM_MAJOR;
368  disk->first_minor = i;
369  disk->fops = &xpram_devops;
370  disk->private_data = &xpram_devices[i];
371  disk->queue = xpram_queues[i];
372  sprintf(disk->disk_name, "slram%d", i);
373  set_capacity(disk, xpram_sizes[i] << 1);
374  add_disk(disk);
375  }
376 
377  return 0;
378 out:
379  while (i--) {
380  blk_cleanup_queue(xpram_queues[i]);
381  put_disk(xpram_disks[i]);
382  }
383  return rc;
384 }
385 
386 /*
387  * Resume failed: Print error message and call panic.
388  */
389 static void xpram_resume_error(const char *message)
390 {
391  pr_err("Resuming the system failed: %s\n", message);
392  panic("xpram resume error\n");
393 }
394 
395 /*
396  * Check if xpram setup changed between suspend and resume.
397  */
398 static int xpram_restore(struct device *dev)
399 {
400  if (!xpram_pages)
401  return 0;
402  if (xpram_present() != 0)
403  xpram_resume_error("xpram disappeared");
404  if (xpram_pages != xpram_highest_page_index() + 1)
405  xpram_resume_error("Size of xpram changed");
406  return 0;
407 }
408 
409 static const struct dev_pm_ops xpram_pm_ops = {
410  .restore = xpram_restore,
411 };
412 
413 static struct platform_driver xpram_pdrv = {
414  .driver = {
415  .name = XPRAM_NAME,
416  .owner = THIS_MODULE,
417  .pm = &xpram_pm_ops,
418  },
419 };
420 
421 static struct platform_device *xpram_pdev;
422 
423 /*
424  * Finally, the init/exit functions.
425  */
426 static void __exit xpram_exit(void)
427 {
428  int i;
429  for (i = 0; i < xpram_devs; i++) {
430  del_gendisk(xpram_disks[i]);
431  blk_cleanup_queue(xpram_queues[i]);
432  put_disk(xpram_disks[i]);
433  }
434  unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
435  platform_device_unregister(xpram_pdev);
436  platform_driver_unregister(&xpram_pdrv);
437 }
438 
439 static int __init xpram_init(void)
440 {
441  int rc;
442 
443  /* Find out size of expanded memory. */
444  if (xpram_present() != 0) {
445  pr_err("No expanded memory available\n");
446  return -ENODEV;
447  }
448  xpram_pages = xpram_highest_page_index() + 1;
449  pr_info(" %u pages expanded memory found (%lu KB).\n",
450  xpram_pages, (unsigned long) xpram_pages*4);
451  rc = xpram_setup_sizes(xpram_pages);
452  if (rc)
453  return rc;
454  rc = platform_driver_register(&xpram_pdrv);
455  if (rc)
456  return rc;
457  xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
458  if (IS_ERR(xpram_pdev)) {
459  rc = PTR_ERR(xpram_pdev);
460  goto fail_platform_driver_unregister;
461  }
462  rc = xpram_setup_blkdev();
463  if (rc)
464  goto fail_platform_device_unregister;
465  return 0;
466 
467 fail_platform_device_unregister:
468  platform_device_unregister(xpram_pdev);
469 fail_platform_driver_unregister:
470  platform_driver_unregister(&xpram_pdrv);
471  return rc;
472 }
473 
474 module_init(xpram_init);
475 module_exit(xpram_exit);
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