xref: /linux/arch/xtensa/platforms/iss/simdisk.c (revision e3966940559d52aa1800a008dcfeec218dd31f88) 
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/string_choices.h>
18 #include <linux/blkdev.h>
19 #include <linux/bio.h>
20 #include <linux/proc_fs.h>
21 #include <linux/uaccess.h>
22 #include <platform/simcall.h>
23 
24 #define SIMDISK_MAJOR 240
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 gendisk *gd;
32 	struct proc_dir_entry *procfile;
33 	int users;
34 	unsigned long size;
35 	int fd;
36 };
37 
38 
39 static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
40 module_param(simdisk_count, int, S_IRUGO);
41 MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
42 
43 static int n_files;
44 static const char *filename[MAX_SIMDISK_COUNT] = {
45 #ifdef CONFIG_SIMDISK0_FILENAME
46 	CONFIG_SIMDISK0_FILENAME,
47 #ifdef CONFIG_SIMDISK1_FILENAME
48 	CONFIG_SIMDISK1_FILENAME,
49 #endif
50 #endif
51 };
52 
53 static int simdisk_param_set_filename(const char *val,
54 		const struct kernel_param *kp)
55 {
56 	if (n_files < ARRAY_SIZE(filename))
57 		filename[n_files++] = val;
58 	else
59 		return -EINVAL;
60 	return 0;
61 }
62 
63 static const struct kernel_param_ops simdisk_param_ops_filename = {
64 	.set = simdisk_param_set_filename,
65 };
66 module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
67 MODULE_PARM_DESC(filename, "Backing storage filename.");
68 
69 static int simdisk_major = SIMDISK_MAJOR;
70 
71 static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
72 		unsigned long nsect, char *buffer, int write)
73 {
74 	unsigned long offset = sector << SECTOR_SHIFT;
75 	unsigned long nbytes = nsect << SECTOR_SHIFT;
76 
77 	if (offset > dev->size || dev->size - offset < nbytes) {
78 		pr_notice("Beyond-end %s (%ld %ld)\n",
79 				str_write_read(write), offset, nbytes);
80 		return;
81 	}
82 
83 	spin_lock(&dev->lock);
84 	while (nbytes > 0) {
85 		unsigned long io;
86 
87 		simc_lseek(dev->fd, offset, SEEK_SET);
88 		READ_ONCE(*buffer);
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_submit_bio(struct bio *bio)
105 {
106 	struct simdisk *dev = bio->bi_bdev->bd_disk->private_data;
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 = bvec_kmap_local(&bvec);
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 		kunmap_local(buffer);
119 	}
120 
121 	bio_endio(bio);
122 }
123 
124 static int simdisk_open(struct gendisk *disk, blk_mode_t mode)
125 {
126 	struct simdisk *dev = disk->private_data;
127 
128 	spin_lock(&dev->lock);
129 	++dev->users;
130 	spin_unlock(&dev->lock);
131 	return 0;
132 }
133 
134 static void simdisk_release(struct gendisk *disk)
135 {
136 	struct simdisk *dev = disk->private_data;
137 	spin_lock(&dev->lock);
138 	--dev->users;
139 	spin_unlock(&dev->lock);
140 }
141 
142 static const struct block_device_operations simdisk_ops = {
143 	.owner		= THIS_MODULE,
144 	.submit_bio	= simdisk_submit_bio,
145 	.open		= simdisk_open,
146 	.release	= simdisk_release,
147 };
148 
149 static struct simdisk *sddev;
150 static struct proc_dir_entry *simdisk_procdir;
151 
152 static int simdisk_attach(struct simdisk *dev, const char *filename)
153 {
154 	int err = 0;
155 
156 	filename = kstrdup(filename, GFP_KERNEL);
157 	if (filename == NULL)
158 		return -ENOMEM;
159 
160 	spin_lock(&dev->lock);
161 
162 	if (dev->fd != -1) {
163 		err = -EBUSY;
164 		goto out;
165 	}
166 	dev->fd = simc_open(filename, O_RDWR, 0);
167 	if (dev->fd == -1) {
168 		pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
169 		err = -ENODEV;
170 		goto out;
171 	}
172 	dev->size = simc_lseek(dev->fd, 0, SEEK_END);
173 	set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
174 	dev->filename = filename;
175 	pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
176 out:
177 	if (err)
178 		kfree(filename);
179 	spin_unlock(&dev->lock);
180 
181 	return err;
182 }
183 
184 static int simdisk_detach(struct simdisk *dev)
185 {
186 	int err = 0;
187 
188 	spin_lock(&dev->lock);
189 
190 	if (dev->users != 0) {
191 		err = -EBUSY;
192 	} else if (dev->fd != -1) {
193 		if (simc_close(dev->fd)) {
194 			pr_err("SIMDISK: error closing %s: %d\n",
195 					dev->filename, errno);
196 			err = -EIO;
197 		} else {
198 			pr_info("SIMDISK: %s detached from %s\n",
199 					dev->gd->disk_name, dev->filename);
200 			dev->fd = -1;
201 			kfree(dev->filename);
202 			dev->filename = NULL;
203 		}
204 	}
205 	spin_unlock(&dev->lock);
206 	return err;
207 }
208 
209 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
210 			size_t size, loff_t *ppos)
211 {
212 	struct simdisk *dev = pde_data(file_inode(file));
213 	const char *s = dev->filename;
214 	if (s) {
215 		ssize_t len = strlen(s);
216 		char *temp = kmalloc(len + 2, GFP_KERNEL);
217 
218 		if (!temp)
219 			return -ENOMEM;
220 
221 		len = scnprintf(temp, len + 2, "%s\n", s);
222 		len = simple_read_from_buffer(buf, size, ppos,
223 					      temp, len);
224 
225 		kfree(temp);
226 		return len;
227 	}
228 	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
229 }
230 
231 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
232 			size_t count, loff_t *ppos)
233 {
234 	char *tmp;
235 	struct simdisk *dev = pde_data(file_inode(file));
236 	int err;
237 
238 	if (count == 0 || count > PAGE_SIZE)
239 		return -EINVAL;
240 
241 	tmp = memdup_user_nul(buf, count);
242 	if (IS_ERR(tmp))
243 		return PTR_ERR(tmp);
244 
245 	err = simdisk_detach(dev);
246 	if (err != 0)
247 		goto out_free;
248 
249 	if (count > 0 && tmp[count - 1] == '\n')
250 		tmp[count - 1] = 0;
251 
252 	if (tmp[0])
253 		err = simdisk_attach(dev, tmp);
254 
255 	if (err == 0)
256 		err = count;
257 out_free:
258 	kfree(tmp);
259 	return err;
260 }
261 
262 static const struct proc_ops simdisk_proc_ops = {
263 	.proc_read	= proc_read_simdisk,
264 	.proc_write	= proc_write_simdisk,
265 	.proc_lseek	= default_llseek,
266 };
267 
268 static int __init simdisk_setup(struct simdisk *dev, int which,
269 		struct proc_dir_entry *procdir)
270 {
271 	struct queue_limits lim = {
272 		.features		= BLK_FEAT_ROTATIONAL,
273 	};
274 	char tmp[2] = { '0' + which, 0 };
275 	int err;
276 
277 	dev->fd = -1;
278 	dev->filename = NULL;
279 	spin_lock_init(&dev->lock);
280 	dev->users = 0;
281 
282 	dev->gd = blk_alloc_disk(&lim, NUMA_NO_NODE);
283 	if (IS_ERR(dev->gd)) {
284 		err = PTR_ERR(dev->gd);
285 		goto out;
286 	}
287 	dev->gd->major = simdisk_major;
288 	dev->gd->first_minor = which;
289 	dev->gd->minors = SIMDISK_MINORS;
290 	dev->gd->fops = &simdisk_ops;
291 	dev->gd->private_data = dev;
292 	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
293 	set_capacity(dev->gd, 0);
294 	err = add_disk(dev->gd);
295 	if (err)
296 		goto out_cleanup_disk;
297 
298 	dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
299 
300 	return 0;
301 
302 out_cleanup_disk:
303 	put_disk(dev->gd);
304 out:
305 	return err;
306 }
307 
308 static int __init simdisk_init(void)
309 {
310 	int i;
311 
312 	if (register_blkdev(simdisk_major, "simdisk") < 0) {
313 		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
314 		return -EIO;
315 	}
316 	pr_info("SIMDISK: major: %d\n", simdisk_major);
317 
318 	if (n_files > simdisk_count)
319 		simdisk_count = n_files;
320 	if (simdisk_count > MAX_SIMDISK_COUNT)
321 		simdisk_count = MAX_SIMDISK_COUNT;
322 
323 	sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
324 	if (sddev == NULL)
325 		goto out_unregister;
326 
327 	simdisk_procdir = proc_mkdir("simdisk", 0);
328 	if (simdisk_procdir == NULL)
329 		goto out_free_unregister;
330 
331 	for (i = 0; i < simdisk_count; ++i) {
332 		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
333 			if (filename[i] != NULL && filename[i][0] != 0 &&
334 					(n_files == 0 || i < n_files))
335 				simdisk_attach(sddev + i, filename[i]);
336 		}
337 	}
338 
339 	return 0;
340 
341 out_free_unregister:
342 	kfree(sddev);
343 out_unregister:
344 	unregister_blkdev(simdisk_major, "simdisk");
345 	return -ENOMEM;
346 }
347 module_init(simdisk_init);
348 
349 static void simdisk_teardown(struct simdisk *dev, int which,
350 		struct proc_dir_entry *procdir)
351 {
352 	char tmp[2] = { '0' + which, 0 };
353 
354 	simdisk_detach(dev);
355 	if (dev->gd) {
356 		del_gendisk(dev->gd);
357 		put_disk(dev->gd);
358 	}
359 	remove_proc_entry(tmp, procdir);
360 }
361 
362 static void __exit simdisk_exit(void)
363 {
364 	int i;
365 
366 	for (i = 0; i < simdisk_count; ++i)
367 		simdisk_teardown(sddev + i, i, simdisk_procdir);
368 	remove_proc_entry("simdisk", 0);
369 	kfree(sddev);
370 	unregister_blkdev(simdisk_major, "simdisk");
371 }
372 module_exit(simdisk_exit);
373 
374 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
375 
376 MODULE_LICENSE("GPL");
377