simdisk.c

  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
 28struct 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
 39static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
 40module_param(simdisk_count, int, S_IRUGO);
 41MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
 42
 43static int n_files;
 44static 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
 53static 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
 63static const struct kernel_param_ops simdisk_param_ops_filename = {
 64	.set = simdisk_param_set_filename,
 65};
 66module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
 67MODULE_PARM_DESC(filename, "Backing storage filename.");
 68
 69static int simdisk_major = SIMDISK_MAJOR;
 70
 71static 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
104static 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
124static 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
134static 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
142static 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
149static struct simdisk *sddev;
150static struct proc_dir_entry *simdisk_procdir;
151
152static 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);
176out:
177	if (err)
178		kfree(filename);
179	spin_unlock(&dev->lock);
180
181	return err;
182}
183
184static 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
209static 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
231static 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;
257out_free:
258	kfree(tmp);
259	return err;
260}
261
262static 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
268static 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
302out_cleanup_disk:
303	put_disk(dev->gd);
304out:
305	return err;
306}
307
308static 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
341out_free_unregister:
342	kfree(sddev);
343out_unregister:
344	unregister_blkdev(simdisk_major, "simdisk");
345	return -ENOMEM;
346}
347module_init(simdisk_init);
348
349static 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
362static 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}
372module_exit(simdisk_exit);
373
374MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
375
376MODULE_LICENSE("GPL");