aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/tile-srom.c
blob: 7faeb1cde97d3e10a128326295b9570a3bfb9912 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
/*
 * Copyright 2011 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * SPI Flash ROM driver
 *
 * This source code is derived from code provided in "Linux Device
 * Drivers, Third Edition", by Jonathan Corbet, Alessandro Rubini, and
 * Greg Kroah-Hartman, published by O'Reilly Media, Inc.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/kernel.h>	/* printk() */
#include <linux/slab.h>		/* kmalloc() */
#include <linux/fs.h>		/* everything... */
#include <linux/errno.h>	/* error codes */
#include <linux/types.h>	/* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h>	/* O_ACCMODE */
#include <linux/aio.h>
#include <linux/pagemap.h>
#include <linux/hugetlb.h>
#include <linux/uaccess.h>
#include <linux/platform_device.h>
#include <hv/hypervisor.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <hv/drv_srom_intf.h>

/*
 * Size of our hypervisor I/O requests.  We break up large transfers
 * so that we don't spend large uninterrupted spans of time in the
 * hypervisor.  Erasing an SROM sector takes a significant fraction of
 * a second, so if we allowed the user to, say, do one I/O to write the
 * entire ROM, we'd get soft lockup timeouts, or worse.
 */
#define SROM_CHUNK_SIZE ((size_t)4096)

/*
 * When hypervisor is busy (e.g. erasing), poll the status periodically.
 */

/*
 * Interval to poll the state in msec
 */
#define SROM_WAIT_TRY_INTERVAL 20

/*
 * Maximum times to poll the state
 */
#define SROM_MAX_WAIT_TRY_TIMES 1000

struct srom_dev {
	int hv_devhdl;			/* Handle for hypervisor device */
	u32 total_size;			/* Size of this device */
	u32 sector_size;		/* Size of a sector */
	u32 page_size;			/* Size of a page */
	struct mutex lock;		/* Allow only one accessor at a time */
};

static int srom_major;			/* Dynamic major by default */
module_param(srom_major, int, 0);
MODULE_AUTHOR("Tilera Corporation");
MODULE_LICENSE("GPL");

static int srom_devs;			/* Number of SROM partitions */
static struct cdev srom_cdev;
static struct class *srom_class;
static struct srom_dev *srom_devices;

/*
 * Handle calling the hypervisor and managing EAGAIN/EBUSY.
 */

static ssize_t _srom_read(int hv_devhdl, void *buf,
			  loff_t off, size_t count)
{
	int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
	for (;;) {
		retval = hv_dev_pread(hv_devhdl, 0, (HV_VirtAddr)buf,
				      count, off);
		if (retval >= 0)
			return retval;
		if (retval == HV_EAGAIN)
			continue;
		if (retval == HV_EBUSY && --retries > 0) {
			msleep(SROM_WAIT_TRY_INTERVAL);
			continue;
		}
		pr_err("_srom_read: error %d\n", retval);
		return -EIO;
	}
}

static ssize_t _srom_write(int hv_devhdl, const void *buf,
			   loff_t off, size_t count)
{
	int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
	for (;;) {
		retval = hv_dev_pwrite(hv_devhdl, 0, (HV_VirtAddr)buf,
				       count, off);
		if (retval >= 0)
			return retval;
		if (retval == HV_EAGAIN)
			continue;
		if (retval == HV_EBUSY && --retries > 0) {
			msleep(SROM_WAIT_TRY_INTERVAL);
			continue;
		}
		pr_err("_srom_write: error %d\n", retval);
		return -EIO;
	}
}

/**
 * srom_open() - Device open routine.
 * @inode: Inode for this device.
 * @filp: File for this specific open of the device.
 *
 * Returns zero, or an error code.
 */
static int srom_open(struct inode *inode, struct file *filp)
{
	filp->private_data = &srom_devices[iminor(inode)];
	return 0;
}


/**
 * srom_release() - Device release routine.
 * @inode: Inode for this device.
 * @filp: File for this specific open of the device.
 *
 * Returns zero, or an error code.
 */
static int srom_release(struct inode *inode, struct file *filp)
{
	struct srom_dev *srom = filp->private_data;
	char dummy;

	/* Make sure we've flushed anything written to the ROM. */
	mutex_lock(&srom->lock);
	if (srom->hv_devhdl >= 0)
		_srom_write(srom->hv_devhdl, &dummy, SROM_FLUSH_OFF, 1);
	mutex_unlock(&srom->lock);

	filp->private_data = NULL;

	return 0;
}


/**
 * srom_read() - Read data from the device.
 * @filp: File for this specific open of the device.
 * @buf: User's data buffer.
 * @count: Number of bytes requested.
 * @f_pos: File position.
 *
 * Returns number of bytes read, or an error code.
 */
static ssize_t srom_read(struct file *filp, char __user *buf,
			 size_t count, loff_t *f_pos)
{
	int retval = 0;
	void *kernbuf;
	struct srom_dev *srom = filp->private_data;

	kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
	if (!kernbuf)
		return -ENOMEM;

	if (mutex_lock_interruptible(&srom->lock)) {
		retval = -ERESTARTSYS;
		kfree(kernbuf);
		return retval;
	}

	while (count) {
		int hv_retval;
		int bytes_this_pass = min(count, SROM_CHUNK_SIZE);

		hv_retval = _srom_read(srom->hv_devhdl, kernbuf,
				       *f_pos, bytes_this_pass);
		if (hv_retval <= 0) {
			if (retval == 0)
				retval = hv_retval;
			break;
		}

		if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
			retval = -EFAULT;
			break;
		}

		retval += hv_retval;
		*f_pos += hv_retval;
		buf += hv_retval;
		count -= hv_retval;
	}

	mutex_unlock(&srom->lock);
	kfree(kernbuf);

	return retval;
}

/**
 * srom_write() - Write data to the device.
 * @filp: File for this specific open of the device.
 * @buf: User's data buffer.
 * @count: Number of bytes requested.
 * @f_pos: File position.
 *
 * Returns number of bytes written, or an error code.
 */
static ssize_t srom_write(struct file *filp, const char __user *buf,
			  size_t count, loff_t *f_pos)
{
	int retval = 0;
	void *kernbuf;
	struct srom_dev *srom = filp->private_data;

	kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
	if (!kernbuf)
		return -ENOMEM;

	if (mutex_lock_interruptible(&srom->lock)) {
		retval = -ERESTARTSYS;
		kfree(kernbuf);
		return retval;
	}

	while (count) {
		int hv_retval;
		int bytes_this_pass = min(count, SROM_CHUNK_SIZE);

		if (copy_from_user(kernbuf, buf, bytes_this_pass) != 0) {
			retval = -EFAULT;
			break;
		}

		hv_retval = _srom_write(srom->hv_devhdl, kernbuf,
					*f_pos, bytes_this_pass);
		if (hv_retval <= 0) {
			if (retval == 0)
				retval = hv_retval;
			break;
		}

		retval += hv_retval;
		*f_pos += hv_retval;
		buf += hv_retval;
		count -= hv_retval;
	}

	mutex_unlock(&srom->lock);
	kfree(kernbuf);

	return retval;
}

/* Provide our own implementation so we can use srom->total_size. */
loff_t srom_llseek(struct file *file, loff_t offset, int origin)
{
	struct srom_dev *srom = file->private_data;
	return fixed_size_llseek(file, offset, origin, srom->total_size);
}

static ssize_t total_show(struct device *dev,
			  struct device_attribute *attr, char *buf)
{
	struct srom_dev *srom = dev_get_drvdata(dev);
	return sprintf(buf, "%u\n", srom->total_size);
}

static ssize_t sector_show(struct device *dev,
			   struct device_attribute *attr, char *buf)
{
	struct srom_dev *srom = dev_get_drvdata(dev);
	return sprintf(buf, "%u\n", srom->sector_size);
}

static ssize_t page_show(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	struct srom_dev *srom = dev_get_drvdata(dev);
	return sprintf(buf, "%u\n", srom->page_size);
}

static struct device_attribute srom_dev_attrs[] = {
	__ATTR(total_size, S_IRUGO, total_show, NULL),
	__ATTR(sector_size, S_IRUGO, sector_show, NULL),
	__ATTR(page_size, S_IRUGO, page_show, NULL),
	__ATTR_NULL
};

static char *srom_devnode(struct device *dev, umode_t *mode)
{
	*mode = S_IRUGO | S_IWUSR;
	return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
}

/*
 * The fops
 */
static const struct file_operations srom_fops = {
	.owner =     THIS_MODULE,
	.llseek =    srom_llseek,
	.read =	     srom_read,
	.write =     srom_write,
	.open =	     srom_open,
	.release =   srom_release,
};

/**
 * srom_setup_minor() - Initialize per-minor information.
 * @srom: Per-device SROM state.
 * @index: Device to set up.
 */
static int srom_setup_minor(struct srom_dev *srom, int index)
{
	struct device *dev;
	int devhdl = srom->hv_devhdl;

	mutex_init(&srom->lock);

	if (_srom_read(devhdl, &srom->total_size,
		       SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
		return -EIO;
	if (_srom_read(devhdl, &srom->sector_size,
		       SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
		return -EIO;
	if (_srom_read(devhdl, &srom->page_size,
		       SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
		return -EIO;

	dev = device_create(srom_class, &platform_bus,
			    MKDEV(srom_major, index), srom, "%d", index);
	return PTR_RET(dev);
}

/** srom_init() - Initialize the driver's module. */
static int srom_init(void)
{
	int result, i;
	dev_t dev = MKDEV(srom_major, 0);

	/*
	 * Start with a plausible number of partitions; the krealloc() call
	 * below will yield about log(srom_devs) additional allocations.
	 */
	srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL);

	/* Discover the number of srom partitions. */
	for (i = 0; ; i++) {
		int devhdl;
		char buf[20];
		struct srom_dev *new_srom_devices =
			krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
				 GFP_KERNEL | __GFP_ZERO);
		if (!new_srom_devices) {
			result = -ENOMEM;
			goto fail_mem;
		}
		srom_devices = new_srom_devices;
		sprintf(buf, "srom/0/%d", i);
		devhdl = hv_dev_open((HV_VirtAddr)buf, 0);
		if (devhdl < 0) {
			if (devhdl != HV_ENODEV)
				pr_notice("srom/%d: hv_dev_open failed: %d.\n",
					  i, devhdl);
			break;
		}
		srom_devices[i].hv_devhdl = devhdl;
	}
	srom_devs = i;

	/* Bail out early if we have no partitions at all. */
	if (srom_devs == 0) {
		result = -ENODEV;
		goto fail_mem;
	}

	/* Register our major, and accept a dynamic number. */
	if (srom_major)
		result = register_chrdev_region(dev, srom_devs, "srom");
	else {
		result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
		srom_major = MAJOR(dev);
	}
	if (result < 0)
		goto fail_mem;

	/* Register a character device. */
	cdev_init(&srom_cdev, &srom_fops);
	srom_cdev.owner = THIS_MODULE;
	srom_cdev.ops = &srom_fops;
	result = cdev_add(&srom_cdev, dev, srom_devs);
	if (result < 0)
		goto fail_chrdev;

	/* Create a sysfs class. */
	srom_class = class_create(THIS_MODULE, "srom");
	if (IS_ERR(srom_class)) {
		result = PTR_ERR(srom_class);
		goto fail_cdev;
	}
	srom_class->dev_attrs = srom_dev_attrs;
	srom_class->devnode = srom_devnode;

	/* Do per-partition initialization */
	for (i = 0; i < srom_devs; i++) {
		result = srom_setup_minor(srom_devices + i, i);
		if (result < 0)
			goto fail_class;
	}

	return 0;

fail_class:
	for (i = 0; i < srom_devs; i++)
		device_destroy(srom_class, MKDEV(srom_major, i));
	class_destroy(srom_class);
fail_cdev:
	cdev_del(&srom_cdev);
fail_chrdev:
	unregister_chrdev_region(dev, srom_devs);
fail_mem:
	kfree(srom_devices);
	return result;
}

/** srom_cleanup() - Clean up the driver's module. */
static void srom_cleanup(void)
{
	int i;
	for (i = 0; i < srom_devs; i++)
		device_destroy(srom_class, MKDEV(srom_major, i));
	class_destroy(srom_class);
	cdev_del(&srom_cdev);
	unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
	kfree(srom_devices);
}

module_init(srom_init);
module_exit(srom_cleanup);