1 /*
2  * arch/xtensa/platforms/iss/simdisk.c
3  *
4  * This file is subject to the terms and conditions of the GNU General Public
5  * License.  See the file "COPYING" in the main directory of this archive
6  * for more details.
7  *
8  * Copyright (C) 2001-2013 Tensilica Inc.
9  *   Authors	Victor Prupis
10  */
11 
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
17 #include <linux/blkdev.h>
18 #include <linux/bio.h>
19 #include <linux/proc_fs.h>
20 #include <asm/uaccess.h>
21 #include <platform/simcall.h>
22 
23 #define SIMDISK_MAJOR 240
24 #define SECTOR_SHIFT 9
25 #define SIMDISK_MINORS 1
26 #define MAX_SIMDISK_COUNT 10
27 
28 struct simdisk {
29 	const char *filename;
30 	spinlock_t lock;
31 	struct request_queue *queue;
32 	struct gendisk *gd;
33 	struct proc_dir_entry *procfile;
34 	int users;
35 	unsigned long size;
36 	int fd;
37 };
38 
39 
40 static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
41 module_param(simdisk_count, int, S_IRUGO);
42 MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
43 
44 static int n_files;
45 static const char *filename[MAX_SIMDISK_COUNT] = {
46 #ifdef CONFIG_SIMDISK0_FILENAME
47 	CONFIG_SIMDISK0_FILENAME,
48 #ifdef CONFIG_SIMDISK1_FILENAME
49 	CONFIG_SIMDISK1_FILENAME,
50 #endif
51 #endif
52 };
53 
54 static int simdisk_param_set_filename(const char *val,
55 		const struct kernel_param *kp)
56 {
57 	if (n_files < ARRAY_SIZE(filename))
58 		filename[n_files++] = val;
59 	else
60 		return -EINVAL;
61 	return 0;
62 }
63 
64 static const struct kernel_param_ops simdisk_param_ops_filename = {
65 	.set = simdisk_param_set_filename,
66 };
67 module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
68 MODULE_PARM_DESC(filename, "Backing storage filename.");
69 
70 static int simdisk_major = SIMDISK_MAJOR;
71 
72 static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
73 		unsigned long nsect, char *buffer, int write)
74 {
75 	unsigned long offset = sector << SECTOR_SHIFT;
76 	unsigned long nbytes = nsect << SECTOR_SHIFT;
77 
78 	if (offset > dev->size || dev->size - offset < nbytes) {
79 		pr_notice("Beyond-end %s (%ld %ld)\n",
80 				write ? "write" : "read", offset, nbytes);
81 		return;
82 	}
83 
84 	spin_lock(&dev->lock);
85 	while (nbytes > 0) {
86 		unsigned long io;
87 
88 		simc_lseek(dev->fd, offset, SEEK_SET);
89 		if (write)
90 			io = simc_write(dev->fd, buffer, nbytes);
91 		else
92 			io = simc_read(dev->fd, buffer, nbytes);
93 		if (io == -1) {
94 			pr_err("SIMDISK: IO error %d\n", errno);
95 			break;
96 		}
97 		buffer += io;
98 		offset += io;
99 		nbytes -= io;
100 	}
101 	spin_unlock(&dev->lock);
102 }
103 
104 static int simdisk_xfer_bio(struct simdisk *dev, struct bio *bio)
105 {
106 	struct bio_vec bvec;
107 	struct bvec_iter iter;
108 	sector_t sector = bio->bi_iter.bi_sector;
109 
110 	bio_for_each_segment(bvec, bio, iter) {
111 		char *buffer = __bio_kmap_atomic(bio, iter);
112 		unsigned len = bvec.bv_len >> SECTOR_SHIFT;
113 
114 		simdisk_transfer(dev, sector, len, buffer,
115 				bio_data_dir(bio) == WRITE);
116 		sector += len;
117 		__bio_kunmap_atomic(buffer);
118 	}
119 	return 0;
120 }
121 
122 static void simdisk_make_request(struct request_queue *q, struct bio *bio)
123 {
124 	struct simdisk *dev = q->queuedata;
125 	int status = simdisk_xfer_bio(dev, bio);
126 	bio_endio(bio, status);
127 }
128 
129 
130 static int simdisk_open(struct block_device *bdev, fmode_t mode)
131 {
132 	struct simdisk *dev = bdev->bd_disk->private_data;
133 
134 	spin_lock(&dev->lock);
135 	if (!dev->users)
136 		check_disk_change(bdev);
137 	++dev->users;
138 	spin_unlock(&dev->lock);
139 	return 0;
140 }
141 
142 static void simdisk_release(struct gendisk *disk, fmode_t mode)
143 {
144 	struct simdisk *dev = disk->private_data;
145 	spin_lock(&dev->lock);
146 	--dev->users;
147 	spin_unlock(&dev->lock);
148 }
149 
150 static const struct block_device_operations simdisk_ops = {
151 	.owner		= THIS_MODULE,
152 	.open		= simdisk_open,
153 	.release	= simdisk_release,
154 };
155 
156 static struct simdisk *sddev;
157 static struct proc_dir_entry *simdisk_procdir;
158 
159 static int simdisk_attach(struct simdisk *dev, const char *filename)
160 {
161 	int err = 0;
162 
163 	filename = kstrdup(filename, GFP_KERNEL);
164 	if (filename == NULL)
165 		return -ENOMEM;
166 
167 	spin_lock(&dev->lock);
168 
169 	if (dev->fd != -1) {
170 		err = -EBUSY;
171 		goto out;
172 	}
173 	dev->fd = simc_open(filename, O_RDWR, 0);
174 	if (dev->fd == -1) {
175 		pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
176 		err = -ENODEV;
177 		goto out;
178 	}
179 	dev->size = simc_lseek(dev->fd, 0, SEEK_END);
180 	set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
181 	dev->filename = filename;
182 	pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
183 out:
184 	if (err)
185 		kfree(filename);
186 	spin_unlock(&dev->lock);
187 
188 	return err;
189 }
190 
191 static int simdisk_detach(struct simdisk *dev)
192 {
193 	int err = 0;
194 
195 	spin_lock(&dev->lock);
196 
197 	if (dev->users != 0) {
198 		err = -EBUSY;
199 	} else if (dev->fd != -1) {
200 		if (simc_close(dev->fd)) {
201 			pr_err("SIMDISK: error closing %s: %d\n",
202 					dev->filename, errno);
203 			err = -EIO;
204 		} else {
205 			pr_info("SIMDISK: %s detached from %s\n",
206 					dev->gd->disk_name, dev->filename);
207 			dev->fd = -1;
208 			kfree(dev->filename);
209 			dev->filename = NULL;
210 		}
211 	}
212 	spin_unlock(&dev->lock);
213 	return err;
214 }
215 
216 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
217 			size_t size, loff_t *ppos)
218 {
219 	struct simdisk *dev = PDE_DATA(file_inode(file));
220 	const char *s = dev->filename;
221 	if (s) {
222 		ssize_t n = simple_read_from_buffer(buf, size, ppos,
223 							s, strlen(s));
224 		if (n < 0)
225 			return n;
226 		buf += n;
227 		size -= n;
228 	}
229 	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
230 }
231 
232 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
233 			size_t count, loff_t *ppos)
234 {
235 	char *tmp = kmalloc(count + 1, GFP_KERNEL);
236 	struct simdisk *dev = PDE_DATA(file_inode(file));
237 	int err;
238 
239 	if (tmp == NULL)
240 		return -ENOMEM;
241 	if (copy_from_user(tmp, buf, count)) {
242 		err = -EFAULT;
243 		goto out_free;
244 	}
245 
246 	err = simdisk_detach(dev);
247 	if (err != 0)
248 		goto out_free;
249 
250 	if (count > 0 && tmp[count - 1] == '\n')
251 		tmp[count - 1] = 0;
252 	else
253 		tmp[count] = 0;
254 
255 	if (tmp[0])
256 		err = simdisk_attach(dev, tmp);
257 
258 	if (err == 0)
259 		err = count;
260 out_free:
261 	kfree(tmp);
262 	return err;
263 }
264 
265 static const struct file_operations fops = {
266 	.read = proc_read_simdisk,
267 	.write = proc_write_simdisk,
268 	.llseek = default_llseek,
269 };
270 
271 static int __init simdisk_setup(struct simdisk *dev, int which,
272 		struct proc_dir_entry *procdir)
273 {
274 	char tmp[2] = { '0' + which, 0 };
275 
276 	dev->fd = -1;
277 	dev->filename = NULL;
278 	spin_lock_init(&dev->lock);
279 	dev->users = 0;
280 
281 	dev->queue = blk_alloc_queue(GFP_KERNEL);
282 	if (dev->queue == NULL) {
283 		pr_err("blk_alloc_queue failed\n");
284 		goto out_alloc_queue;
285 	}
286 
287 	blk_queue_make_request(dev->queue, simdisk_make_request);
288 	dev->queue->queuedata = dev;
289 
290 	dev->gd = alloc_disk(SIMDISK_MINORS);
291 	if (dev->gd == NULL) {
292 		pr_err("alloc_disk failed\n");
293 		goto out_alloc_disk;
294 	}
295 	dev->gd->major = simdisk_major;
296 	dev->gd->first_minor = which;
297 	dev->gd->fops = &simdisk_ops;
298 	dev->gd->queue = dev->queue;
299 	dev->gd->private_data = dev;
300 	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
301 	set_capacity(dev->gd, 0);
302 	add_disk(dev->gd);
303 
304 	dev->procfile = proc_create_data(tmp, 0644, procdir, &fops, dev);
305 	return 0;
306 
307 out_alloc_disk:
308 	blk_cleanup_queue(dev->queue);
309 	dev->queue = NULL;
310 out_alloc_queue:
311 	simc_close(dev->fd);
312 	return -EIO;
313 }
314 
315 static int __init simdisk_init(void)
316 {
317 	int i;
318 
319 	if (register_blkdev(simdisk_major, "simdisk") < 0) {
320 		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
321 		return -EIO;
322 	}
323 	pr_info("SIMDISK: major: %d\n", simdisk_major);
324 
325 	if (n_files > simdisk_count)
326 		simdisk_count = n_files;
327 	if (simdisk_count > MAX_SIMDISK_COUNT)
328 		simdisk_count = MAX_SIMDISK_COUNT;
329 
330 	sddev = kmalloc(simdisk_count * sizeof(struct simdisk),
331 			GFP_KERNEL);
332 	if (sddev == NULL)
333 		goto out_unregister;
334 
335 	simdisk_procdir = proc_mkdir("simdisk", 0);
336 	if (simdisk_procdir == NULL)
337 		goto out_free_unregister;
338 
339 	for (i = 0; i < simdisk_count; ++i) {
340 		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
341 			if (filename[i] != NULL && filename[i][0] != 0 &&
342 					(n_files == 0 || i < n_files))
343 				simdisk_attach(sddev + i, filename[i]);
344 		}
345 	}
346 
347 	return 0;
348 
349 out_free_unregister:
350 	kfree(sddev);
351 out_unregister:
352 	unregister_blkdev(simdisk_major, "simdisk");
353 	return -ENOMEM;
354 }
355 module_init(simdisk_init);
356 
357 static void simdisk_teardown(struct simdisk *dev, int which,
358 		struct proc_dir_entry *procdir)
359 {
360 	char tmp[2] = { '0' + which, 0 };
361 
362 	simdisk_detach(dev);
363 	if (dev->gd)
364 		del_gendisk(dev->gd);
365 	if (dev->queue)
366 		blk_cleanup_queue(dev->queue);
367 	remove_proc_entry(tmp, procdir);
368 }
369 
370 static void __exit simdisk_exit(void)
371 {
372 	int i;
373 
374 	for (i = 0; i < simdisk_count; ++i)
375 		simdisk_teardown(sddev + i, i, simdisk_procdir);
376 	remove_proc_entry("simdisk", 0);
377 	kfree(sddev);
378 	unregister_blkdev(simdisk_major, "simdisk");
379 }
380 module_exit(simdisk_exit);
381 
382 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
383 
384 MODULE_LICENSE("GPL");
385