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#include <linux/module.h>
29#include <linux/moduleparam.h>
30#include <linux/ctype.h>  /* isdigit, isxdigit */
31#include <linux/errno.h>
32#include <linux/init.h>
33#include <linux/slab.h>
34#include <linux/blkdev.h>
35#include <linux/blkpg.h>
36#include <linux/hdreg.h>  /* HDIO_GETGEO */
37#include <linux/sysdev.h>
38#include <linux/bio.h>
39#include <asm/uaccess.h>
40
41#define XPRAM_NAME	"xpram"
42#define XPRAM_DEVS	1	/* one partition */
43#define XPRAM_MAX_DEVS	32	/* maximal number of devices (partitions) */
44
45#define PRINT_DEBUG(x...)	printk(KERN_DEBUG XPRAM_NAME " debug:" x)
46#define PRINT_INFO(x...)	printk(KERN_INFO XPRAM_NAME " info:" x)
47#define PRINT_WARN(x...)	printk(KERN_WARNING XPRAM_NAME " warning:" x)
48#define PRINT_ERR(x...)		printk(KERN_ERR XPRAM_NAME " error:" x)
49
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 unsigned int xpram_pages;
60static int xpram_devs;
61
62/*
63 * Parameter parsing functions.
64 */
65static int __initdata devs = XPRAM_DEVS;
66static char __initdata *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		PRINT_ERR("expanded storage lost!\n");
105		return -ENXIO;
106	}
107	if (cc == 1) {
108		PRINT_ERR("page in failed for page index %u.\n",
109			  xpage_index);
110		return -EIO;
111	}
112	return 0;
113}
114
115/*
116 * Copy a 4kB page of main memory to an expanded memory page
117 * Arguments
118 *           page_addr:    address of source page
119 *           xpage_index:  index of expandeded memory page
120 * Return value
121 *           0:            if operation succeeds
122 *           -EIO:         if pgout failed
123 *           -ENXIO:       if xpram has vanished
124 */
125static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
126{
127	int cc = 2;	/* return unused cc 2 if pgin traps */
128
129	asm volatile(
130		"	.insn	rre,0xb22f0000,%1,%2\n"  /* pgout %1,%2 */
131		"0:	ipm	%0\n"
132		"	srl	%0,28\n"
133		"1:\n"
134		EX_TABLE(0b,1b)
135		: "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
136	if (cc == 3)
137		return -ENXIO;
138	if (cc == 2) {
139		PRINT_ERR("expanded storage lost!\n");
140		return -ENXIO;
141	}
142	if (cc == 1) {
143		PRINT_ERR("page out failed for page index %u.\n",
144			  xpage_index);
145		return -EIO;
146	}
147	return 0;
148}
149
150/*
151 * Check if xpram is available.
152 */
153static int __init xpram_present(void)
154{
155	unsigned long mem_page;
156	int rc;
157
158	mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
159	if (!mem_page)
160		return -ENOMEM;
161	rc = xpram_page_in(mem_page, 0);
162	free_page(mem_page);
163	return rc ? -ENXIO : 0;
164}
165
166/*
167 * Return index of the last available xpram page.
168 */
169static unsigned long __init xpram_highest_page_index(void)
170{
171	unsigned int page_index, add_bit;
172	unsigned long mem_page;
173
174	mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
175	if (!mem_page)
176		return 0;
177
178	page_index = 0;
179	add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
180	while (add_bit > 0) {
181		if (xpram_page_in(mem_page, page_index | add_bit) == 0)
182			page_index |= add_bit;
183		add_bit >>= 1;
184	}
185
186	free_page (mem_page);
187
188	return page_index;
189}
190
191/*
192 * Block device make request function.
193 */
194static int xpram_make_request(request_queue_t *q, struct bio *bio)
195{
196	xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
197	struct bio_vec *bvec;
198	unsigned int index;
199	unsigned long page_addr;
200	unsigned long bytes;
201	int i;
202
203	if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
204		/* Request is not page-aligned. */
205		goto fail;
206	if ((bio->bi_size >> 12) > xdev->size)
207		/* Request size is no page-aligned. */
208		goto fail;
209	if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
210		goto fail;
211	index = (bio->bi_sector >> 3) + xdev->offset;
212	bio_for_each_segment(bvec, bio, i) {
213		page_addr = (unsigned long)
214			kmap(bvec->bv_page) + bvec->bv_offset;
215		bytes = bvec->bv_len;
216		if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
217			/* More paranoia. */
218			goto fail;
219		while (bytes > 0) {
220			if (bio_data_dir(bio) == READ) {
221				if (xpram_page_in(page_addr, index) != 0)
222					goto fail;
223			} else {
224				if (xpram_page_out(page_addr, index) != 0)
225					goto fail;
226			}
227			page_addr += 4096;
228			bytes -= 4096;
229			index++;
230		}
231	}
232	set_bit(BIO_UPTODATE, &bio->bi_flags);
233	bytes = bio->bi_size;
234	bio->bi_size = 0;
235	bio->bi_end_io(bio, bytes, 0);
236	return 0;
237fail:
238	bio_io_error(bio, bio->bi_size);
239	return 0;
240}
241
242static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
243{
244	unsigned long size;
245
246	/*
247	 * get geometry: we have to fake one...  trim the size to a
248	 * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
249	 * whatever cylinders. Tell also that data starts at sector. 4.
250	 */
251	size = (xpram_pages * 8) & ~0x3f;
252	geo->cylinders = size >> 6;
253	geo->heads = 4;
254	geo->sectors = 16;
255	geo->start = 4;
256	return 0;
257}
258
259static struct block_device_operations xpram_devops =
260{
261	.owner	= THIS_MODULE,
262	.getgeo	= xpram_getgeo,
263};
264
265/*
266 * Setup xpram_sizes array.
267 */
268static int __init xpram_setup_sizes(unsigned long pages)
269{
270	unsigned long mem_needed;
271	unsigned long mem_auto;
272	unsigned long long size;
273	int mem_auto_no;
274	int i;
275
276	/* Check number of devices. */
277	if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
278		PRINT_ERR("invalid number %d of devices\n",devs);
279		return -EINVAL;
280	}
281	xpram_devs = devs;
282
283	/*
284	 * Copy sizes array to xpram_sizes and align partition
285	 * sizes to page boundary.
286	 */
287	mem_needed = 0;
288	mem_auto_no = 0;
289	for (i = 0; i < xpram_devs; i++) {
290		if (sizes[i]) {
291			size = simple_strtoull(sizes[i], &sizes[i], 0);
292			switch (sizes[i][0]) {
293			case 'g':
294			case 'G':
295				size <<= 20;
296				break;
297			case 'm':
298			case 'M':
299				size <<= 10;
300			}
301			xpram_sizes[i] = (size + 3) & -4UL;
302		}
303		if (xpram_sizes[i])
304			mem_needed += xpram_sizes[i];
305		else
306			mem_auto_no++;
307	}
308
309	PRINT_INFO("  number of devices (partitions): %d \n", xpram_devs);
310	for (i = 0; i < xpram_devs; i++) {
311		if (xpram_sizes[i])
312			PRINT_INFO("  size of partition %d: %u kB\n",
313				   i, xpram_sizes[i]);
314		else
315			PRINT_INFO("  size of partition %d to be set "
316				   "automatically\n",i);
317	}
318	PRINT_DEBUG("  memory needed (for sized partitions): %lu kB\n",
319		    mem_needed);
320	PRINT_DEBUG("  partitions to be sized automatically: %d\n",
321		    mem_auto_no);
322
323	if (mem_needed > pages * 4) {
324		PRINT_ERR("Not enough expanded memory available\n");
325		return -EINVAL;
326	}
327
328	/*
329	 * partitioning:
330	 * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
331	 * else:             ; all partitions with zero xpram_sizes[i]
332	 *                     partition equally the remaining space
333	 */
334	if (mem_auto_no) {
335		mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
336		PRINT_INFO("  automatically determined "
337			   "partition size: %lu kB\n", mem_auto);
338		for (i = 0; i < xpram_devs; i++)
339			if (xpram_sizes[i] == 0)
340				xpram_sizes[i] = mem_auto;
341	}
342	return 0;
343}
344
345static struct request_queue *xpram_queue;
346
347static int __init xpram_setup_blkdev(void)
348{
349	unsigned long offset;
350	int i, rc = -ENOMEM;
351
352	for (i = 0; i < xpram_devs; i++) {
353		struct gendisk *disk = alloc_disk(1);
354		if (!disk)
355			goto out;
356		xpram_disks[i] = disk;
357	}
358
359	/*
360	 * Register xpram major.
361	 */
362	rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
363	if (rc < 0)
364		goto out;
365
366	/*
367	 * Assign the other needed values: make request function, sizes and
368	 * hardsect size. All the minor devices feature the same value.
369	 */
370	xpram_queue = blk_alloc_queue(GFP_KERNEL);
371	if (!xpram_queue) {
372		rc = -ENOMEM;
373		goto out_unreg;
374	}
375	blk_queue_make_request(xpram_queue, xpram_make_request);
376	blk_queue_hardsect_size(xpram_queue, 4096);
377
378	/*
379	 * Setup device structures.
380	 */
381	offset = 0;
382	for (i = 0; i < xpram_devs; i++) {
383		struct gendisk *disk = xpram_disks[i];
384
385		xpram_devices[i].size = xpram_sizes[i] / 4;
386		xpram_devices[i].offset = offset;
387		offset += xpram_devices[i].size;
388		disk->major = XPRAM_MAJOR;
389		disk->first_minor = i;
390		disk->fops = &xpram_devops;
391		disk->private_data = &xpram_devices[i];
392		disk->queue = xpram_queue;
393		sprintf(disk->disk_name, "slram%d", i);
394		set_capacity(disk, xpram_sizes[i] << 1);
395		add_disk(disk);
396	}
397
398	return 0;
399out_unreg:
400	unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
401out:
402	while (i--)
403		put_disk(xpram_disks[i]);
404	return rc;
405}
406
407/*
408 * Finally, the init/exit functions.
409 */
410static void __exit xpram_exit(void)
411{
412	int i;
413	for (i = 0; i < xpram_devs; i++) {
414		del_gendisk(xpram_disks[i]);
415		put_disk(xpram_disks[i]);
416	}
417	unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
418	blk_cleanup_queue(xpram_queue);
419}
420
421static int __init xpram_init(void)
422{
423	int rc;
424
425	/* Find out size of expanded memory. */
426	if (xpram_present() != 0) {
427		PRINT_WARN("No expanded memory available\n");
428		return -ENODEV;
429	}
430	xpram_pages = xpram_highest_page_index() + 1;
431	PRINT_INFO("  %u pages expanded memory found (%lu KB).\n",
432		   xpram_pages, (unsigned long) xpram_pages*4);
433	rc = xpram_setup_sizes(xpram_pages);
434	if (rc)
435		return rc;
436	return xpram_setup_blkdev();
437}
438
439module_init(xpram_init);
440module_exit(xpram_exit);
441