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
28struct 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
40static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
41module_param(simdisk_count, int, S_IRUGO);
42MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
43
44static int n_files;
45static 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
54static 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
64static const struct kernel_param_ops simdisk_param_ops_filename = {
65	.set = simdisk_param_set_filename,
66};
67module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
68MODULE_PARM_DESC(filename, "Backing storage filename.");
69
70static int simdisk_major = SIMDISK_MAJOR;
71
72static 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
104static 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
122static 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
130static 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
142static 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
150static const struct block_device_operations simdisk_ops = {
151	.owner		= THIS_MODULE,
152	.open		= simdisk_open,
153	.release	= simdisk_release,
154};
155
156static struct simdisk *sddev;
157static struct proc_dir_entry *simdisk_procdir;
158
159static 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);
183out:
184	if (err)
185		kfree(filename);
186	spin_unlock(&dev->lock);
187
188	return err;
189}
190
191static 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
216static 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
232static 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;
260out_free:
261	kfree(tmp);
262	return err;
263}
264
265static const struct file_operations fops = {
266	.read = proc_read_simdisk,
267	.write = proc_write_simdisk,
268	.llseek = default_llseek,
269};
270
271static 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
307out_alloc_disk:
308	blk_cleanup_queue(dev->queue);
309	dev->queue = NULL;
310out_alloc_queue:
311	simc_close(dev->fd);
312	return -EIO;
313}
314
315static 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
349out_free_unregister:
350	kfree(sddev);
351out_unregister:
352	unregister_blkdev(simdisk_major, "simdisk");
353	return -ENOMEM;
354}
355module_init(simdisk_init);
356
357static 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
370static 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}
380module_exit(simdisk_exit);
381
382MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
383
384MODULE_LICENSE("GPL");
385