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
51typedef 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
56static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
57static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
58static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
59static struct request_queue *xpram_queues[XPRAM_MAX_DEVS];
60static unsigned int xpram_pages;
61static int xpram_devs;
62
63/*
64 * Parameter parsing functions.
65 */
66static int devs = XPRAM_DEVS;
67static char *sizes[XPRAM_MAX_DEVS];
68
69module_param(devs, int, 0);
70module_param_array(sizes, charp, NULL, 0);
71
72MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
73		 "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
74MODULE_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");
79MODULE_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 */
91static 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 */
121static 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 */
144static 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 */
160static 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 */
185static blk_qc_t xpram_submit_bio(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(&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;
228fail:
229	bio_io_error(bio);
230	return BLK_QC_T_NONE;
231}
232
233static 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
250static const struct block_device_operations xpram_devops =
251{
252	.owner	= THIS_MODULE,
253	.submit_bio = xpram_submit_bio,
254	.getgeo	= xpram_getgeo,
255};
256
257/*
258 * Setup xpram_sizes array.
259 */
260static int __init xpram_setup_sizes(unsigned long pages)
261{
262	unsigned long mem_needed;
263	unsigned long mem_auto;
264	unsigned long long size;
265	char *sizes_end;
266	int mem_auto_no;
267	int i;
268
269	/* Check number of devices. */
270	if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
271		pr_err("%d is not a valid number of XPRAM devices\n",devs);
272		return -EINVAL;
273	}
274	xpram_devs = devs;
275
276	/*
277	 * Copy sizes array to xpram_sizes and align partition
278	 * sizes to page boundary.
279	 */
280	mem_needed = 0;
281	mem_auto_no = 0;
282	for (i = 0; i < xpram_devs; i++) {
283		if (sizes[i]) {
284			size = simple_strtoull(sizes[i], &sizes_end, 0);
285			switch (*sizes_end) {
286			case 'g':
287			case 'G':
288				size <<= 20;
289				break;
290			case 'm':
291			case 'M':
292				size <<= 10;
293			}
294			xpram_sizes[i] = (size + 3) & -4UL;
295		}
296		if (xpram_sizes[i])
297			mem_needed += xpram_sizes[i];
298		else
299			mem_auto_no++;
300	}
301
302	pr_info("  number of devices (partitions): %d \n", xpram_devs);
303	for (i = 0; i < xpram_devs; i++) {
304		if (xpram_sizes[i])
305			pr_info("  size of partition %d: %u kB\n",
306				i, xpram_sizes[i]);
307		else
308			pr_info("  size of partition %d to be set "
309				"automatically\n",i);
310	}
311	pr_info("  memory needed (for sized partitions): %lu kB\n",
312		mem_needed);
313	pr_info("  partitions to be sized automatically: %d\n",
314		mem_auto_no);
315
316	if (mem_needed > pages * 4) {
317		pr_err("Not enough expanded memory available\n");
318		return -EINVAL;
319	}
320
321	/*
322	 * partitioning:
323	 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
324	 * else:             ; all partitions with zero xpram_sizes[i]
325	 *                     partition equally the remaining space
326	 */
327	if (mem_auto_no) {
328		mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
329		pr_info("  automatically determined "
330			"partition size: %lu kB\n", mem_auto);
331		for (i = 0; i < xpram_devs; i++)
332			if (xpram_sizes[i] == 0)
333				xpram_sizes[i] = mem_auto;
334	}
335	return 0;
336}
337
338static int __init xpram_setup_blkdev(void)
339{
340	unsigned long offset;
341	int i, rc = -ENOMEM;
342
343	for (i = 0; i < xpram_devs; i++) {
344		xpram_disks[i] = alloc_disk(1);
345		if (!xpram_disks[i])
346			goto out;
347		xpram_queues[i] = blk_alloc_queue(NUMA_NO_NODE);
348		if (!xpram_queues[i]) {
349			put_disk(xpram_disks[i]);
350			goto out;
351		}
352		blk_queue_flag_set(QUEUE_FLAG_NONROT, xpram_queues[i]);
353		blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
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;
385out:
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 */
396static 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 */
405static 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
416static const struct dev_pm_ops xpram_pm_ops = {
417	.restore	= xpram_restore,
418};
419
420static struct platform_driver xpram_pdrv = {
421	.driver = {
422		.name	= XPRAM_NAME,
423		.pm	= &xpram_pm_ops,
424	},
425};
426
427static struct platform_device *xpram_pdev;
428
429/*
430 * Finally, the init/exit functions.
431 */
432static 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
445static 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
473fail_platform_device_unregister:
474	platform_device_unregister(xpram_pdev);
475fail_platform_driver_unregister:
476	platform_driver_unregister(&xpram_pdrv);
477	return rc;
478}
479
480module_init(xpram_init);
481module_exit(xpram_exit);
482