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
27struct 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
38static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
39module_param(simdisk_count, int, S_IRUGO);
40MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
41
42static int n_files;
43static 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
52static 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
62static const struct kernel_param_ops simdisk_param_ops_filename = {
63	.set = simdisk_param_set_filename,
64};
65module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
66MODULE_PARM_DESC(filename, "Backing storage filename.");
67
68static int simdisk_major = SIMDISK_MAJOR;
69
70static 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
103static 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
123static 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
133static 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
141static 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
148static struct simdisk *sddev;
149static struct proc_dir_entry *simdisk_procdir;
150
151static 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);
175out:
176	if (err)
177		kfree(filename);
178	spin_unlock(&dev->lock);
179
180	return err;
181}
182
183static 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
208static 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
230static 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;
252out_free:
253	kfree(tmp);
254	return err;
255}
256
257static 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
263static 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 = -ENOMEM;
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(NUMA_NO_NODE);
275	if (!dev->gd)
276		goto out;
277	dev->gd->major = simdisk_major;
278	dev->gd->first_minor = which;
279	dev->gd->minors = SIMDISK_MINORS;
280	dev->gd->fops = &simdisk_ops;
281	dev->gd->private_data = dev;
282	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
283	set_capacity(dev->gd, 0);
284	err = add_disk(dev->gd);
285	if (err)
286		goto out_cleanup_disk;
287
288	dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
289
290	return 0;
291
292out_cleanup_disk:
293	put_disk(dev->gd);
294out:
295	return err;
296}
297
298static int __init simdisk_init(void)
299{
300	int i;
301
302	if (register_blkdev(simdisk_major, "simdisk") < 0) {
303		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
304		return -EIO;
305	}
306	pr_info("SIMDISK: major: %d\n", simdisk_major);
307
308	if (n_files > simdisk_count)
309		simdisk_count = n_files;
310	if (simdisk_count > MAX_SIMDISK_COUNT)
311		simdisk_count = MAX_SIMDISK_COUNT;
312
313	sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
314	if (sddev == NULL)
315		goto out_unregister;
316
317	simdisk_procdir = proc_mkdir("simdisk", 0);
318	if (simdisk_procdir == NULL)
319		goto out_free_unregister;
320
321	for (i = 0; i < simdisk_count; ++i) {
322		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
323			if (filename[i] != NULL && filename[i][0] != 0 &&
324					(n_files == 0 || i < n_files))
325				simdisk_attach(sddev + i, filename[i]);
326		}
327	}
328
329	return 0;
330
331out_free_unregister:
332	kfree(sddev);
333out_unregister:
334	unregister_blkdev(simdisk_major, "simdisk");
335	return -ENOMEM;
336}
337module_init(simdisk_init);
338
339static void simdisk_teardown(struct simdisk *dev, int which,
340		struct proc_dir_entry *procdir)
341{
342	char tmp[2] = { '0' + which, 0 };
343
344	simdisk_detach(dev);
345	if (dev->gd) {
346		del_gendisk(dev->gd);
347		put_disk(dev->gd);
348	}
349	remove_proc_entry(tmp, procdir);
350}
351
352static void __exit simdisk_exit(void)
353{
354	int i;
355
356	for (i = 0; i < simdisk_count; ++i)
357		simdisk_teardown(sddev + i, i, simdisk_procdir);
358	remove_proc_entry("simdisk", 0);
359	kfree(sddev);
360	unregister_blkdev(simdisk_major, "simdisk");
361}
362module_exit(simdisk_exit);
363
364MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
365
366MODULE_LICENSE("GPL");
367