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
50typedef 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
55static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
56static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
57static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
58static struct request_queue *xpram_queues[XPRAM_MAX_DEVS];
59static unsigned int xpram_pages;
60static int xpram_devs;
61
62/*
63 * Parameter parsing functions.
64 */
65static int devs = XPRAM_DEVS;
66static char *sizes[XPRAM_MAX_DEVS];
67
68module_param(devs, int, 0);
69module_param_array(sizes, charp, NULL, 0);
70
71MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
72		 "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
73MODULE_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");
78MODULE_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 */
90static 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 */
120static 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 */
143static 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 */
159static 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 */
184static 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;
227fail:
228	bio_io_error(bio);
229	return BLK_QC_T_NONE;
230}
231
232static 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
249static 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 */
258static 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
336static 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;
384out:
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 */
395static 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 */
404static 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
415static const struct dev_pm_ops xpram_pm_ops = {
416	.restore	= xpram_restore,
417};
418
419static struct platform_driver xpram_pdrv = {
420	.driver = {
421		.name	= XPRAM_NAME,
422		.pm	= &xpram_pm_ops,
423	},
424};
425
426static struct platform_device *xpram_pdev;
427
428/*
429 * Finally, the init/exit functions.
430 */
431static 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
444static 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
472fail_platform_device_unregister:
473	platform_device_unregister(xpram_pdev);
474fail_platform_driver_unregister:
475	platform_driver_unregister(&xpram_pdrv);
476	return rc;
477}
478
479module_init(xpram_init);
480module_exit(xpram_exit);
481