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 void simdisk_make_request(struct request_queue *q, struct bio *bio)
105 {
106 	struct simdisk *dev = q->queuedata;
107 	struct bio_vec bvec;
108 	struct bvec_iter iter;
109 	sector_t sector = bio->bi_iter.bi_sector;
110 
111 	bio_for_each_segment(bvec, bio, iter) {
112 		char *buffer = __bio_kmap_atomic(bio, iter);
113 		unsigned len = bvec.bv_len >> SECTOR_SHIFT;
114 
115 		simdisk_transfer(dev, sector, len, buffer,
116 				bio_data_dir(bio) == WRITE);
117 		sector += len;
118 		__bio_kunmap_atomic(buffer);
119 	}
120 
121 	bio_endio(bio);
122 }
123 
124 static int simdisk_open(struct block_device *bdev, fmode_t mode)
125 {
126 	struct simdisk *dev = bdev->bd_disk->private_data;
127 
128 	spin_lock(&dev->lock);
129 	if (!dev->users)
130 		check_disk_change(bdev);
131 	++dev->users;
132 	spin_unlock(&dev->lock);
133 	return 0;
134 }
135 
136 static void simdisk_release(struct gendisk *disk, fmode_t mode)
137 {
138 	struct simdisk *dev = disk->private_data;
139 	spin_lock(&dev->lock);
140 	--dev->users;
141 	spin_unlock(&dev->lock);
142 }
143 
144 static const struct block_device_operations simdisk_ops = {
145 	.owner		= THIS_MODULE,
146 	.open		= simdisk_open,
147 	.release	= simdisk_release,
148 };
149 
150 static struct simdisk *sddev;
151 static struct proc_dir_entry *simdisk_procdir;
152 
153 static int simdisk_attach(struct simdisk *dev, const char *filename)
154 {
155 	int err = 0;
156 
157 	filename = kstrdup(filename, GFP_KERNEL);
158 	if (filename == NULL)
159 		return -ENOMEM;
160 
161 	spin_lock(&dev->lock);
162 
163 	if (dev->fd != -1) {
164 		err = -EBUSY;
165 		goto out;
166 	}
167 	dev->fd = simc_open(filename, O_RDWR, 0);
168 	if (dev->fd == -1) {
169 		pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
170 		err = -ENODEV;
171 		goto out;
172 	}
173 	dev->size = simc_lseek(dev->fd, 0, SEEK_END);
174 	set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
175 	dev->filename = filename;
176 	pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
177 out:
178 	if (err)
179 		kfree(filename);
180 	spin_unlock(&dev->lock);
181 
182 	return err;
183 }
184 
185 static int simdisk_detach(struct simdisk *dev)
186 {
187 	int err = 0;
188 
189 	spin_lock(&dev->lock);
190 
191 	if (dev->users != 0) {
192 		err = -EBUSY;
193 	} else if (dev->fd != -1) {
194 		if (simc_close(dev->fd)) {
195 			pr_err("SIMDISK: error closing %s: %d\n",
196 					dev->filename, errno);
197 			err = -EIO;
198 		} else {
199 			pr_info("SIMDISK: %s detached from %s\n",
200 					dev->gd->disk_name, dev->filename);
201 			dev->fd = -1;
202 			kfree(dev->filename);
203 			dev->filename = NULL;
204 		}
205 	}
206 	spin_unlock(&dev->lock);
207 	return err;
208 }
209 
210 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
211 			size_t size, loff_t *ppos)
212 {
213 	struct simdisk *dev = PDE_DATA(file_inode(file));
214 	const char *s = dev->filename;
215 	if (s) {
216 		ssize_t n = simple_read_from_buffer(buf, size, ppos,
217 							s, strlen(s));
218 		if (n < 0)
219 			return n;
220 		buf += n;
221 		size -= n;
222 	}
223 	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
224 }
225 
226 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
227 			size_t count, loff_t *ppos)
228 {
229 	char *tmp = kmalloc(count + 1, GFP_KERNEL);
230 	struct simdisk *dev = PDE_DATA(file_inode(file));
231 	int err;
232 
233 	if (tmp == NULL)
234 		return -ENOMEM;
235 	if (copy_from_user(tmp, buf, count)) {
236 		err = -EFAULT;
237 		goto out_free;
238 	}
239 
240 	err = simdisk_detach(dev);
241 	if (err != 0)
242 		goto out_free;
243 
244 	if (count > 0 && tmp[count - 1] == '\n')
245 		tmp[count - 1] = 0;
246 	else
247 		tmp[count] = 0;
248 
249 	if (tmp[0])
250 		err = simdisk_attach(dev, tmp);
251 
252 	if (err == 0)
253 		err = count;
254 out_free:
255 	kfree(tmp);
256 	return err;
257 }
258 
259 static const struct file_operations fops = {
260 	.read = proc_read_simdisk,
261 	.write = proc_write_simdisk,
262 	.llseek = default_llseek,
263 };
264 
265 static int __init simdisk_setup(struct simdisk *dev, int which,
266 		struct proc_dir_entry *procdir)
267 {
268 	char tmp[2] = { '0' + which, 0 };
269 
270 	dev->fd = -1;
271 	dev->filename = NULL;
272 	spin_lock_init(&dev->lock);
273 	dev->users = 0;
274 
275 	dev->queue = blk_alloc_queue(GFP_KERNEL);
276 	if (dev->queue == NULL) {
277 		pr_err("blk_alloc_queue failed\n");
278 		goto out_alloc_queue;
279 	}
280 
281 	blk_queue_make_request(dev->queue, simdisk_make_request);
282 	dev->queue->queuedata = dev;
283 
284 	dev->gd = alloc_disk(SIMDISK_MINORS);
285 	if (dev->gd == NULL) {
286 		pr_err("alloc_disk failed\n");
287 		goto out_alloc_disk;
288 	}
289 	dev->gd->major = simdisk_major;
290 	dev->gd->first_minor = which;
291 	dev->gd->fops = &simdisk_ops;
292 	dev->gd->queue = dev->queue;
293 	dev->gd->private_data = dev;
294 	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
295 	set_capacity(dev->gd, 0);
296 	add_disk(dev->gd);
297 
298 	dev->procfile = proc_create_data(tmp, 0644, procdir, &fops, dev);
299 	return 0;
300 
301 out_alloc_disk:
302 	blk_cleanup_queue(dev->queue);
303 	dev->queue = NULL;
304 out_alloc_queue:
305 	simc_close(dev->fd);
306 	return -EIO;
307 }
308 
309 static int __init simdisk_init(void)
310 {
311 	int i;
312 
313 	if (register_blkdev(simdisk_major, "simdisk") < 0) {
314 		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
315 		return -EIO;
316 	}
317 	pr_info("SIMDISK: major: %d\n", simdisk_major);
318 
319 	if (n_files > simdisk_count)
320 		simdisk_count = n_files;
321 	if (simdisk_count > MAX_SIMDISK_COUNT)
322 		simdisk_count = MAX_SIMDISK_COUNT;
323 
324 	sddev = kmalloc(simdisk_count * sizeof(struct simdisk),
325 			GFP_KERNEL);
326 	if (sddev == NULL)
327 		goto out_unregister;
328 
329 	simdisk_procdir = proc_mkdir("simdisk", 0);
330 	if (simdisk_procdir == NULL)
331 		goto out_free_unregister;
332 
333 	for (i = 0; i < simdisk_count; ++i) {
334 		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
335 			if (filename[i] != NULL && filename[i][0] != 0 &&
336 					(n_files == 0 || i < n_files))
337 				simdisk_attach(sddev + i, filename[i]);
338 		}
339 	}
340 
341 	return 0;
342 
343 out_free_unregister:
344 	kfree(sddev);
345 out_unregister:
346 	unregister_blkdev(simdisk_major, "simdisk");
347 	return -ENOMEM;
348 }
349 module_init(simdisk_init);
350 
351 static void simdisk_teardown(struct simdisk *dev, int which,
352 		struct proc_dir_entry *procdir)
353 {
354 	char tmp[2] = { '0' + which, 0 };
355 
356 	simdisk_detach(dev);
357 	if (dev->gd)
358 		del_gendisk(dev->gd);
359 	if (dev->queue)
360 		blk_cleanup_queue(dev->queue);
361 	remove_proc_entry(tmp, procdir);
362 }
363 
364 static void __exit simdisk_exit(void)
365 {
366 	int i;
367 
368 	for (i = 0; i < simdisk_count; ++i)
369 		simdisk_teardown(sddev + i, i, simdisk_procdir);
370 	remove_proc_entry("simdisk", 0);
371 	kfree(sddev);
372 	unregister_blkdev(simdisk_major, "simdisk");
373 }
374 module_exit(simdisk_exit);
375 
376 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
377 
378 MODULE_LICENSE("GPL");
379