1 /*******************************************************************************
2  * Filename:  target_core_rd.c
3  *
4  * This file contains the Storage Engine <-> Ramdisk transport
5  * specific functions.
6  *
7  * Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
8  * Copyright (c) 2005, 2006, 2007 SBE, Inc.
9  * Copyright (c) 2007-2010 Rising Tide Systems
10  * Copyright (c) 2008-2010 Linux-iSCSI.org
11  *
12  * Nicholas A. Bellinger <nab@kernel.org>
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License as published by
16  * the Free Software Foundation; either version 2 of the License, or
17  * (at your option) any later version.
18  *
19  * This program is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22  * GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with this program; if not, write to the Free Software
26  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27  *
28  ******************************************************************************/
29 
30 #include <linux/string.h>
31 #include <linux/parser.h>
32 #include <linux/timer.h>
33 #include <linux/blkdev.h>
34 #include <linux/slab.h>
35 #include <linux/spinlock.h>
36 #include <scsi/scsi.h>
37 #include <scsi/scsi_host.h>
38 
39 #include <target/target_core_base.h>
40 #include <target/target_core_backend.h>
41 
42 #include "target_core_rd.h"
43 
44 static inline struct rd_dev *RD_DEV(struct se_device *dev)
45 {
46 	return container_of(dev, struct rd_dev, dev);
47 }
48 
49 /*	rd_attach_hba(): (Part of se_subsystem_api_t template)
50  *
51  *
52  */
53 static int rd_attach_hba(struct se_hba *hba, u32 host_id)
54 {
55 	struct rd_host *rd_host;
56 
57 	rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL);
58 	if (!rd_host) {
59 		pr_err("Unable to allocate memory for struct rd_host\n");
60 		return -ENOMEM;
61 	}
62 
63 	rd_host->rd_host_id = host_id;
64 
65 	hba->hba_ptr = rd_host;
66 
67 	pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
68 		" Generic Target Core Stack %s\n", hba->hba_id,
69 		RD_HBA_VERSION, TARGET_CORE_MOD_VERSION);
70 
71 	return 0;
72 }
73 
74 static void rd_detach_hba(struct se_hba *hba)
75 {
76 	struct rd_host *rd_host = hba->hba_ptr;
77 
78 	pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
79 		" Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);
80 
81 	kfree(rd_host);
82 	hba->hba_ptr = NULL;
83 }
84 
85 /*	rd_release_device_space():
86  *
87  *
88  */
89 static void rd_release_device_space(struct rd_dev *rd_dev)
90 {
91 	u32 i, j, page_count = 0, sg_per_table;
92 	struct rd_dev_sg_table *sg_table;
93 	struct page *pg;
94 	struct scatterlist *sg;
95 
96 	if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
97 		return;
98 
99 	sg_table = rd_dev->sg_table_array;
100 
101 	for (i = 0; i < rd_dev->sg_table_count; i++) {
102 		sg = sg_table[i].sg_table;
103 		sg_per_table = sg_table[i].rd_sg_count;
104 
105 		for (j = 0; j < sg_per_table; j++) {
106 			pg = sg_page(&sg[j]);
107 			if (pg) {
108 				__free_page(pg);
109 				page_count++;
110 			}
111 		}
112 
113 		kfree(sg);
114 	}
115 
116 	pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
117 		" Device ID: %u, pages %u in %u tables total bytes %lu\n",
118 		rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
119 		rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
120 
121 	kfree(sg_table);
122 	rd_dev->sg_table_array = NULL;
123 	rd_dev->sg_table_count = 0;
124 }
125 
126 
127 /*	rd_build_device_space():
128  *
129  *
130  */
131 static int rd_build_device_space(struct rd_dev *rd_dev)
132 {
133 	u32 i = 0, j, page_offset = 0, sg_per_table, sg_tables, total_sg_needed;
134 	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
135 				sizeof(struct scatterlist));
136 	struct rd_dev_sg_table *sg_table;
137 	struct page *pg;
138 	struct scatterlist *sg;
139 
140 	if (rd_dev->rd_page_count <= 0) {
141 		pr_err("Illegal page count: %u for Ramdisk device\n",
142 			rd_dev->rd_page_count);
143 		return -EINVAL;
144 	}
145 	total_sg_needed = rd_dev->rd_page_count;
146 
147 	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
148 
149 	sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
150 	if (!sg_table) {
151 		pr_err("Unable to allocate memory for Ramdisk"
152 			" scatterlist tables\n");
153 		return -ENOMEM;
154 	}
155 
156 	rd_dev->sg_table_array = sg_table;
157 	rd_dev->sg_table_count = sg_tables;
158 
159 	while (total_sg_needed) {
160 		sg_per_table = (total_sg_needed > max_sg_per_table) ?
161 			max_sg_per_table : total_sg_needed;
162 
163 		sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
164 				GFP_KERNEL);
165 		if (!sg) {
166 			pr_err("Unable to allocate scatterlist array"
167 				" for struct rd_dev\n");
168 			return -ENOMEM;
169 		}
170 
171 		sg_init_table(sg, sg_per_table);
172 
173 		sg_table[i].sg_table = sg;
174 		sg_table[i].rd_sg_count = sg_per_table;
175 		sg_table[i].page_start_offset = page_offset;
176 		sg_table[i++].page_end_offset = (page_offset + sg_per_table)
177 						- 1;
178 
179 		for (j = 0; j < sg_per_table; j++) {
180 			pg = alloc_pages(GFP_KERNEL, 0);
181 			if (!pg) {
182 				pr_err("Unable to allocate scatterlist"
183 					" pages for struct rd_dev_sg_table\n");
184 				return -ENOMEM;
185 			}
186 			sg_assign_page(&sg[j], pg);
187 			sg[j].length = PAGE_SIZE;
188 		}
189 
190 		page_offset += sg_per_table;
191 		total_sg_needed -= sg_per_table;
192 	}
193 
194 	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
195 		" %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
196 		rd_dev->rd_dev_id, rd_dev->rd_page_count,
197 		rd_dev->sg_table_count);
198 
199 	return 0;
200 }
201 
202 static struct se_device *rd_alloc_device(struct se_hba *hba, const char *name)
203 {
204 	struct rd_dev *rd_dev;
205 	struct rd_host *rd_host = hba->hba_ptr;
206 
207 	rd_dev = kzalloc(sizeof(struct rd_dev), GFP_KERNEL);
208 	if (!rd_dev) {
209 		pr_err("Unable to allocate memory for struct rd_dev\n");
210 		return NULL;
211 	}
212 
213 	rd_dev->rd_host = rd_host;
214 
215 	return &rd_dev->dev;
216 }
217 
218 static int rd_configure_device(struct se_device *dev)
219 {
220 	struct rd_dev *rd_dev = RD_DEV(dev);
221 	struct rd_host *rd_host = dev->se_hba->hba_ptr;
222 	int ret;
223 
224 	if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
225 		pr_debug("Missing rd_pages= parameter\n");
226 		return -EINVAL;
227 	}
228 
229 	ret = rd_build_device_space(rd_dev);
230 	if (ret < 0)
231 		goto fail;
232 
233 	dev->dev_attrib.hw_block_size = RD_BLOCKSIZE;
234 	dev->dev_attrib.hw_max_sectors = UINT_MAX;
235 	dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
236 
237 	rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
238 
239 	pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
240 		" %u pages in %u tables, %lu total bytes\n",
241 		rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
242 		rd_dev->sg_table_count,
243 		(unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
244 
245 	return 0;
246 
247 fail:
248 	rd_release_device_space(rd_dev);
249 	return ret;
250 }
251 
252 static void rd_free_device(struct se_device *dev)
253 {
254 	struct rd_dev *rd_dev = RD_DEV(dev);
255 
256 	rd_release_device_space(rd_dev);
257 	kfree(rd_dev);
258 }
259 
260 static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
261 {
262 	u32 i;
263 	struct rd_dev_sg_table *sg_table;
264 
265 	for (i = 0; i < rd_dev->sg_table_count; i++) {
266 		sg_table = &rd_dev->sg_table_array[i];
267 		if ((sg_table->page_start_offset <= page) &&
268 		    (sg_table->page_end_offset >= page))
269 			return sg_table;
270 	}
271 
272 	pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
273 			page);
274 
275 	return NULL;
276 }
277 
278 static int rd_execute_rw(struct se_cmd *cmd)
279 {
280 	struct scatterlist *sgl = cmd->t_data_sg;
281 	u32 sgl_nents = cmd->t_data_nents;
282 	enum dma_data_direction data_direction = cmd->data_direction;
283 	struct se_device *se_dev = cmd->se_dev;
284 	struct rd_dev *dev = RD_DEV(se_dev);
285 	struct rd_dev_sg_table *table;
286 	struct scatterlist *rd_sg;
287 	struct sg_mapping_iter m;
288 	u32 rd_offset;
289 	u32 rd_size;
290 	u32 rd_page;
291 	u32 src_len;
292 	u64 tmp;
293 
294 	tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
295 	rd_offset = do_div(tmp, PAGE_SIZE);
296 	rd_page = tmp;
297 	rd_size = cmd->data_length;
298 
299 	table = rd_get_sg_table(dev, rd_page);
300 	if (!table)
301 		return -EINVAL;
302 
303 	rd_sg = &table->sg_table[rd_page - table->page_start_offset];
304 
305 	pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
306 			dev->rd_dev_id,
307 			data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
308 			cmd->t_task_lba, rd_size, rd_page, rd_offset);
309 
310 	src_len = PAGE_SIZE - rd_offset;
311 	sg_miter_start(&m, sgl, sgl_nents,
312 			data_direction == DMA_FROM_DEVICE ?
313 				SG_MITER_TO_SG : SG_MITER_FROM_SG);
314 	while (rd_size) {
315 		u32 len;
316 		void *rd_addr;
317 
318 		sg_miter_next(&m);
319 		len = min((u32)m.length, src_len);
320 		m.consumed = len;
321 
322 		rd_addr = sg_virt(rd_sg) + rd_offset;
323 
324 		if (data_direction == DMA_FROM_DEVICE)
325 			memcpy(m.addr, rd_addr, len);
326 		else
327 			memcpy(rd_addr, m.addr, len);
328 
329 		rd_size -= len;
330 		if (!rd_size)
331 			continue;
332 
333 		src_len -= len;
334 		if (src_len) {
335 			rd_offset += len;
336 			continue;
337 		}
338 
339 		/* rd page completed, next one please */
340 		rd_page++;
341 		rd_offset = 0;
342 		src_len = PAGE_SIZE;
343 		if (rd_page <= table->page_end_offset) {
344 			rd_sg++;
345 			continue;
346 		}
347 
348 		table = rd_get_sg_table(dev, rd_page);
349 		if (!table) {
350 			sg_miter_stop(&m);
351 			return -EINVAL;
352 		}
353 
354 		/* since we increment, the first sg entry is correct */
355 		rd_sg = table->sg_table;
356 	}
357 	sg_miter_stop(&m);
358 
359 	target_complete_cmd(cmd, SAM_STAT_GOOD);
360 	return 0;
361 }
362 
363 enum {
364 	Opt_rd_pages, Opt_err
365 };
366 
367 static match_table_t tokens = {
368 	{Opt_rd_pages, "rd_pages=%d"},
369 	{Opt_err, NULL}
370 };
371 
372 static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
373 		const char *page, ssize_t count)
374 {
375 	struct rd_dev *rd_dev = RD_DEV(dev);
376 	char *orig, *ptr, *opts;
377 	substring_t args[MAX_OPT_ARGS];
378 	int ret = 0, arg, token;
379 
380 	opts = kstrdup(page, GFP_KERNEL);
381 	if (!opts)
382 		return -ENOMEM;
383 
384 	orig = opts;
385 
386 	while ((ptr = strsep(&opts, ",\n")) != NULL) {
387 		if (!*ptr)
388 			continue;
389 
390 		token = match_token(ptr, tokens, args);
391 		switch (token) {
392 		case Opt_rd_pages:
393 			match_int(args, &arg);
394 			rd_dev->rd_page_count = arg;
395 			pr_debug("RAMDISK: Referencing Page"
396 				" Count: %u\n", rd_dev->rd_page_count);
397 			rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
398 			break;
399 		default:
400 			break;
401 		}
402 	}
403 
404 	kfree(orig);
405 	return (!ret) ? count : ret;
406 }
407 
408 static ssize_t rd_show_configfs_dev_params(struct se_device *dev, char *b)
409 {
410 	struct rd_dev *rd_dev = RD_DEV(dev);
411 
412 	ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
413 			rd_dev->rd_dev_id);
414 	bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
415 			"  SG_table_count: %u\n", rd_dev->rd_page_count,
416 			PAGE_SIZE, rd_dev->sg_table_count);
417 	return bl;
418 }
419 
420 static sector_t rd_get_blocks(struct se_device *dev)
421 {
422 	struct rd_dev *rd_dev = RD_DEV(dev);
423 
424 	unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
425 			dev->dev_attrib.block_size) - 1;
426 
427 	return blocks_long;
428 }
429 
430 static struct sbc_ops rd_sbc_ops = {
431 	.execute_rw		= rd_execute_rw,
432 };
433 
434 static int rd_parse_cdb(struct se_cmd *cmd)
435 {
436 	return sbc_parse_cdb(cmd, &rd_sbc_ops);
437 }
438 
439 static struct se_subsystem_api rd_mcp_template = {
440 	.name			= "rd_mcp",
441 	.inquiry_prod		= "RAMDISK-MCP",
442 	.inquiry_rev		= RD_MCP_VERSION,
443 	.transport_type		= TRANSPORT_PLUGIN_VHBA_VDEV,
444 	.attach_hba		= rd_attach_hba,
445 	.detach_hba		= rd_detach_hba,
446 	.alloc_device		= rd_alloc_device,
447 	.configure_device	= rd_configure_device,
448 	.free_device		= rd_free_device,
449 	.parse_cdb		= rd_parse_cdb,
450 	.set_configfs_dev_params = rd_set_configfs_dev_params,
451 	.show_configfs_dev_params = rd_show_configfs_dev_params,
452 	.get_device_rev		= sbc_get_device_rev,
453 	.get_device_type	= sbc_get_device_type,
454 	.get_blocks		= rd_get_blocks,
455 };
456 
457 int __init rd_module_init(void)
458 {
459 	int ret;
460 
461 	ret = transport_subsystem_register(&rd_mcp_template);
462 	if (ret < 0) {
463 		return ret;
464 	}
465 
466 	return 0;
467 }
468 
469 void rd_module_exit(void)
470 {
471 	transport_subsystem_release(&rd_mcp_template);
472 }
473