xref: /linux/arch/xtensa/platforms/iss/simdisk.c (revision 2697b79a469b68e3ad3640f55284359c1396278d) 
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 <linux/uaccess.h>
21 #include <platform/simcall.h>
22 
23 #define SIMDISK_MAJOR 240
24 #define SIMDISK_MINORS 1
25 #define MAX_SIMDISK_COUNT 10
26 
27 struct simdisk {
28 	const char *filename;
29 	spinlock_t lock;
30 	struct gendisk *gd;
31 	struct proc_dir_entry *procfile;
32 	int users;
33 	unsigned long size;
34 	int fd;
35 };
36 
37 
38 static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
39 module_param(simdisk_count, int, S_IRUGO);
40 MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
41 
42 static int n_files;
43 static const char *filename[MAX_SIMDISK_COUNT] = {
44 #ifdef CONFIG_SIMDISK0_FILENAME
45 	CONFIG_SIMDISK0_FILENAME,
46 #ifdef CONFIG_SIMDISK1_FILENAME
47 	CONFIG_SIMDISK1_FILENAME,
48 #endif
49 #endif
50 };
51 
52 static int simdisk_param_set_filename(const char *val,
53 		const struct kernel_param *kp)
54 {
55 	if (n_files < ARRAY_SIZE(filename))
56 		filename[n_files++] = val;
57 	else
58 		return -EINVAL;
59 	return 0;
60 }
61 
62 static const struct kernel_param_ops simdisk_param_ops_filename = {
63 	.set = simdisk_param_set_filename,
64 };
65 module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
66 MODULE_PARM_DESC(filename, "Backing storage filename.");
67 
68 static int simdisk_major = SIMDISK_MAJOR;
69 
70 static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
71 		unsigned long nsect, char *buffer, int write)
72 {
73 	unsigned long offset = sector << SECTOR_SHIFT;
74 	unsigned long nbytes = nsect << SECTOR_SHIFT;
75 
76 	if (offset > dev->size || dev->size - offset < nbytes) {
77 		pr_notice("Beyond-end %s (%ld %ld)\n",
78 				write ? "write" : "read", offset, nbytes);
79 		return;
80 	}
81 
82 	spin_lock(&dev->lock);
83 	while (nbytes > 0) {
84 		unsigned long io;
85 
86 		simc_lseek(dev->fd, offset, SEEK_SET);
87 		READ_ONCE(*buffer);
88 		if (write)
89 			io = simc_write(dev->fd, buffer, nbytes);
90 		else
91 			io = simc_read(dev->fd, buffer, nbytes);
92 		if (io == -1) {
93 			pr_err("SIMDISK: IO error %d\n", errno);
94 			break;
95 		}
96 		buffer += io;
97 		offset += io;
98 		nbytes -= io;
99 	}
100 	spin_unlock(&dev->lock);
101 }
102 
103 static void simdisk_submit_bio(struct bio *bio)
104 {
105 	struct simdisk *dev = bio->bi_bdev->bd_disk->private_data;
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 = bvec_kmap_local(&bvec);
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 		kunmap_local(buffer);
118 	}
119 
120 	bio_endio(bio);
121 }
122 
123 static int simdisk_open(struct gendisk *disk, blk_mode_t mode)
124 {
125 	struct simdisk *dev = disk->private_data;
126 
127 	spin_lock(&dev->lock);
128 	++dev->users;
129 	spin_unlock(&dev->lock);
130 	return 0;
131 }
132 
133 static void simdisk_release(struct gendisk *disk)
134 {
135 	struct simdisk *dev = disk->private_data;
136 	spin_lock(&dev->lock);
137 	--dev->users;
138 	spin_unlock(&dev->lock);
139 }
140 
141 static const struct block_device_operations simdisk_ops = {
142 	.owner		= THIS_MODULE,
143 	.submit_bio	= simdisk_submit_bio,
144 	.open		= simdisk_open,
145 	.release	= simdisk_release,
146 };
147 
148 static struct simdisk *sddev;
149 static struct proc_dir_entry *simdisk_procdir;
150 
151 static int simdisk_attach(struct simdisk *dev, const char *filename)
152 {
153 	int err = 0;
154 
155 	filename = kstrdup(filename, GFP_KERNEL);
156 	if (filename == NULL)
157 		return -ENOMEM;
158 
159 	spin_lock(&dev->lock);
160 
161 	if (dev->fd != -1) {
162 		err = -EBUSY;
163 		goto out;
164 	}
165 	dev->fd = simc_open(filename, O_RDWR, 0);
166 	if (dev->fd == -1) {
167 		pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
168 		err = -ENODEV;
169 		goto out;
170 	}
171 	dev->size = simc_lseek(dev->fd, 0, SEEK_END);
172 	set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
173 	dev->filename = filename;
174 	pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
175 out:
176 	if (err)
177 		kfree(filename);
178 	spin_unlock(&dev->lock);
179 
180 	return err;
181 }
182 
183 static int simdisk_detach(struct simdisk *dev)
184 {
185 	int err = 0;
186 
187 	spin_lock(&dev->lock);
188 
189 	if (dev->users != 0) {
190 		err = -EBUSY;
191 	} else if (dev->fd != -1) {
192 		if (simc_close(dev->fd)) {
193 			pr_err("SIMDISK: error closing %s: %d\n",
194 					dev->filename, errno);
195 			err = -EIO;
196 		} else {
197 			pr_info("SIMDISK: %s detached from %s\n",
198 					dev->gd->disk_name, dev->filename);
199 			dev->fd = -1;
200 			kfree(dev->filename);
201 			dev->filename = NULL;
202 		}
203 	}
204 	spin_unlock(&dev->lock);
205 	return err;
206 }
207 
208 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
209 			size_t size, loff_t *ppos)
210 {
211 	struct simdisk *dev = pde_data(file_inode(file));
212 	const char *s = dev->filename;
213 	if (s) {
214 		ssize_t len = strlen(s);
215 		char *temp = kmalloc(len + 2, GFP_KERNEL);
216 
217 		if (!temp)
218 			return -ENOMEM;
219 
220 		len = scnprintf(temp, len + 2, "%s\n", s);
221 		len = simple_read_from_buffer(buf, size, ppos,
222 					      temp, len);
223 
224 		kfree(temp);
225 		return len;
226 	}
227 	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
228 }
229 
230 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
231 			size_t count, loff_t *ppos)
232 {
233 	char *tmp = memdup_user_nul(buf, count);
234 	struct simdisk *dev = pde_data(file_inode(file));
235 	int err;
236 
237 	if (IS_ERR(tmp))
238 		return PTR_ERR(tmp);
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 
247 	if (tmp[0])
248 		err = simdisk_attach(dev, tmp);
249 
250 	if (err == 0)
251 		err = count;
252 out_free:
253 	kfree(tmp);
254 	return err;
255 }
256 
257 static const struct proc_ops simdisk_proc_ops = {
258 	.proc_read	= proc_read_simdisk,
259 	.proc_write	= proc_write_simdisk,
260 	.proc_lseek	= default_llseek,
261 };
262 
263 static int __init simdisk_setup(struct simdisk *dev, int which,
264 		struct proc_dir_entry *procdir)
265 {
266 	char tmp[2] = { '0' + which, 0 };
267 	int err;
268 
269 	dev->fd = -1;
270 	dev->filename = NULL;
271 	spin_lock_init(&dev->lock);
272 	dev->users = 0;
273 
274 	dev->gd = blk_alloc_disk(NULL, NUMA_NO_NODE);
275 	if (IS_ERR(dev->gd)) {
276 		err = PTR_ERR(dev->gd);
277 		goto out;
278 	}
279 	dev->gd->major = simdisk_major;
280 	dev->gd->first_minor = which;
281 	dev->gd->minors = SIMDISK_MINORS;
282 	dev->gd->fops = &simdisk_ops;
283 	dev->gd->private_data = dev;
284 	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
285 	set_capacity(dev->gd, 0);
286 	err = add_disk(dev->gd);
287 	if (err)
288 		goto out_cleanup_disk;
289 
290 	dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
291 
292 	return 0;
293 
294 out_cleanup_disk:
295 	put_disk(dev->gd);
296 out:
297 	return err;
298 }
299 
300 static int __init simdisk_init(void)
301 {
302 	int i;
303 
304 	if (register_blkdev(simdisk_major, "simdisk") < 0) {
305 		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
306 		return -EIO;
307 	}
308 	pr_info("SIMDISK: major: %d\n", simdisk_major);
309 
310 	if (n_files > simdisk_count)
311 		simdisk_count = n_files;
312 	if (simdisk_count > MAX_SIMDISK_COUNT)
313 		simdisk_count = MAX_SIMDISK_COUNT;
314 
315 	sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
316 	if (sddev == NULL)
317 		goto out_unregister;
318 
319 	simdisk_procdir = proc_mkdir("simdisk", 0);
320 	if (simdisk_procdir == NULL)
321 		goto out_free_unregister;
322 
323 	for (i = 0; i < simdisk_count; ++i) {
324 		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
325 			if (filename[i] != NULL && filename[i][0] != 0 &&
326 					(n_files == 0 || i < n_files))
327 				simdisk_attach(sddev + i, filename[i]);
328 		}
329 	}
330 
331 	return 0;
332 
333 out_free_unregister:
334 	kfree(sddev);
335 out_unregister:
336 	unregister_blkdev(simdisk_major, "simdisk");
337 	return -ENOMEM;
338 }
339 module_init(simdisk_init);
340 
341 static void simdisk_teardown(struct simdisk *dev, int which,
342 		struct proc_dir_entry *procdir)
343 {
344 	char tmp[2] = { '0' + which, 0 };
345 
346 	simdisk_detach(dev);
347 	if (dev->gd) {
348 		del_gendisk(dev->gd);
349 		put_disk(dev->gd);
350 	}
351 	remove_proc_entry(tmp, procdir);
352 }
353 
354 static void __exit simdisk_exit(void)
355 {
356 	int i;
357 
358 	for (i = 0; i < simdisk_count; ++i)
359 		simdisk_teardown(sddev + i, i, simdisk_procdir);
360 	remove_proc_entry("simdisk", 0);
361 	kfree(sddev);
362 	unregister_blkdev(simdisk_major, "simdisk");
363 }
364 module_exit(simdisk_exit);
365 
366 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
367 
368 MODULE_LICENSE("GPL");
369