tile-srom.c revision dbcb4a1a3f16702918caa4d4ab7062965050a780 
1/*
2 * Copyright 2011 Tilera Corporation. All Rights Reserved.
3 *
4 *   This program is free software; you can redistribute it and/or
5 *   modify it under the terms of the GNU General Public License
6 *   as published by the Free Software Foundation, version 2.
7 *
8 *   This program is distributed in the hope that it will be useful, but
9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 *   NON INFRINGEMENT.  See the GNU General Public License for
12 *   more details.
13 *
14 * SPI Flash ROM driver
15 *
16 * This source code is derived from code provided in "Linux Device
17 * Drivers, Third Edition", by Jonathan Corbet, Alessandro Rubini, and
18 * Greg Kroah-Hartman, published by O'Reilly Media, Inc.
19 */
20
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/init.h>
24#include <linux/kernel.h>	/* printk() */
25#include <linux/slab.h>		/* kmalloc() */
26#include <linux/fs.h>		/* everything... */
27#include <linux/errno.h>	/* error codes */
28#include <linux/types.h>	/* size_t */
29#include <linux/proc_fs.h>
30#include <linux/fcntl.h>	/* O_ACCMODE */
31#include <linux/aio.h>
32#include <linux/pagemap.h>
33#include <linux/hugetlb.h>
34#include <linux/uaccess.h>
35#include <linux/platform_device.h>
36#include <hv/hypervisor.h>
37#include <linux/ioctl.h>
38#include <linux/cdev.h>
39#include <linux/delay.h>
40#include <hv/drv_srom_intf.h>
41
42/*
43 * Size of our hypervisor I/O requests.  We break up large transfers
44 * so that we don't spend large uninterrupted spans of time in the
45 * hypervisor.  Erasing an SROM sector takes a significant fraction of
46 * a second, so if we allowed the user to, say, do one I/O to write the
47 * entire ROM, we'd get soft lockup timeouts, or worse.
48 */
49#define SROM_CHUNK_SIZE ((size_t)4096)
50
51/*
52 * When hypervisor is busy (e.g. erasing), poll the status periodically.
53 */
54
55/*
56 * Interval to poll the state in msec
57 */
58#define SROM_WAIT_TRY_INTERVAL 20
59
60/*
61 * Maximum times to poll the state
62 */
63#define SROM_MAX_WAIT_TRY_TIMES 1000
64
65struct srom_dev {
66	int hv_devhdl;			/* Handle for hypervisor device */
67	u32 total_size;			/* Size of this device */
68	u32 sector_size;		/* Size of a sector */
69	u32 page_size;			/* Size of a page */
70	struct mutex lock;		/* Allow only one accessor at a time */
71};
72
73static int srom_major;			/* Dynamic major by default */
74module_param(srom_major, int, 0);
75MODULE_AUTHOR("Tilera Corporation");
76MODULE_LICENSE("GPL");
77
78static int srom_devs;			/* Number of SROM partitions */
79static struct cdev srom_cdev;
80static struct class *srom_class;
81static struct srom_dev *srom_devices;
82
83/*
84 * Handle calling the hypervisor and managing EAGAIN/EBUSY.
85 */
86
87static ssize_t _srom_read(int hv_devhdl, void *buf,
88			  loff_t off, size_t count)
89{
90	int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
91	for (;;) {
92		retval = hv_dev_pread(hv_devhdl, 0, (HV_VirtAddr)buf,
93				      count, off);
94		if (retval >= 0)
95			return retval;
96		if (retval == HV_EAGAIN)
97			continue;
98		if (retval == HV_EBUSY && --retries > 0) {
99			msleep(SROM_WAIT_TRY_INTERVAL);
100			continue;
101		}
102		pr_err("_srom_read: error %d\n", retval);
103		return -EIO;
104	}
105}
106
107static ssize_t _srom_write(int hv_devhdl, const void *buf,
108			   loff_t off, size_t count)
109{
110	int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
111	for (;;) {
112		retval = hv_dev_pwrite(hv_devhdl, 0, (HV_VirtAddr)buf,
113				       count, off);
114		if (retval >= 0)
115			return retval;
116		if (retval == HV_EAGAIN)
117			continue;
118		if (retval == HV_EBUSY && --retries > 0) {
119			msleep(SROM_WAIT_TRY_INTERVAL);
120			continue;
121		}
122		pr_err("_srom_write: error %d\n", retval);
123		return -EIO;
124	}
125}
126
127/**
128 * srom_open() - Device open routine.
129 * @inode: Inode for this device.
130 * @filp: File for this specific open of the device.
131 *
132 * Returns zero, or an error code.
133 */
134static int srom_open(struct inode *inode, struct file *filp)
135{
136	filp->private_data = &srom_devices[iminor(inode)];
137	return 0;
138}
139
140
141/**
142 * srom_release() - Device release routine.
143 * @inode: Inode for this device.
144 * @filp: File for this specific open of the device.
145 *
146 * Returns zero, or an error code.
147 */
148static int srom_release(struct inode *inode, struct file *filp)
149{
150	struct srom_dev *srom = filp->private_data;
151	char dummy;
152
153	/* Make sure we've flushed anything written to the ROM. */
154	mutex_lock(&srom->lock);
155	if (srom->hv_devhdl >= 0)
156		_srom_write(srom->hv_devhdl, &dummy, SROM_FLUSH_OFF, 1);
157	mutex_unlock(&srom->lock);
158
159	filp->private_data = NULL;
160
161	return 0;
162}
163
164
165/**
166 * srom_read() - Read data from the device.
167 * @filp: File for this specific open of the device.
168 * @buf: User's data buffer.
169 * @count: Number of bytes requested.
170 * @f_pos: File position.
171 *
172 * Returns number of bytes read, or an error code.
173 */
174static ssize_t srom_read(struct file *filp, char __user *buf,
175			 size_t count, loff_t *f_pos)
176{
177	int retval = 0;
178	void *kernbuf;
179	struct srom_dev *srom = filp->private_data;
180
181	kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
182	if (!kernbuf)
183		return -ENOMEM;
184
185	if (mutex_lock_interruptible(&srom->lock)) {
186		retval = -ERESTARTSYS;
187		kfree(kernbuf);
188		return retval;
189	}
190
191	while (count) {
192		int hv_retval;
193		int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
194
195		hv_retval = _srom_read(srom->hv_devhdl, kernbuf,
196				       *f_pos, bytes_this_pass);
197		if (hv_retval > 0) {
198			if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
199				retval = -EFAULT;
200				break;
201			}
202		} else if (hv_retval <= 0) {
203			if (retval == 0)
204				retval = hv_retval;
205			break;
206		}
207
208		retval += hv_retval;
209		*f_pos += hv_retval;
210		buf += hv_retval;
211		count -= hv_retval;
212	}
213
214	mutex_unlock(&srom->lock);
215	kfree(kernbuf);
216
217	return retval;
218}
219
220/**
221 * srom_write() - Write data to the device.
222 * @filp: File for this specific open of the device.
223 * @buf: User's data buffer.
224 * @count: Number of bytes requested.
225 * @f_pos: File position.
226 *
227 * Returns number of bytes written, or an error code.
228 */
229static ssize_t srom_write(struct file *filp, const char __user *buf,
230			  size_t count, loff_t *f_pos)
231{
232	int retval = 0;
233	void *kernbuf;
234	struct srom_dev *srom = filp->private_data;
235
236	kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
237	if (!kernbuf)
238		return -ENOMEM;
239
240	if (mutex_lock_interruptible(&srom->lock)) {
241		retval = -ERESTARTSYS;
242		kfree(kernbuf);
243		return retval;
244	}
245
246	while (count) {
247		int hv_retval;
248		int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
249
250		if (copy_from_user(kernbuf, buf, bytes_this_pass) != 0) {
251			retval = -EFAULT;
252			break;
253		}
254
255		hv_retval = _srom_write(srom->hv_devhdl, kernbuf,
256					*f_pos, bytes_this_pass);
257		if (hv_retval <= 0) {
258			if (retval == 0)
259				retval = hv_retval;
260			break;
261		}
262
263		retval += hv_retval;
264		*f_pos += hv_retval;
265		buf += hv_retval;
266		count -= hv_retval;
267	}
268
269	mutex_unlock(&srom->lock);
270	kfree(kernbuf);
271
272	return retval;
273}
274
275/* Provide our own implementation so we can use srom->total_size. */
276loff_t srom_llseek(struct file *filp, loff_t offset, int origin)
277{
278	struct srom_dev *srom = filp->private_data;
279
280	if (mutex_lock_interruptible(&srom->lock))
281		return -ERESTARTSYS;
282
283	switch (origin) {
284	case SEEK_END:
285		offset += srom->total_size;
286		break;
287	case SEEK_CUR:
288		offset += filp->f_pos;
289		break;
290	}
291
292	if (offset < 0 || offset > srom->total_size) {
293		offset = -EINVAL;
294	} else {
295		filp->f_pos = offset;
296		filp->f_version = 0;
297	}
298
299	mutex_unlock(&srom->lock);
300
301	return offset;
302}
303
304static ssize_t total_show(struct device *dev,
305			  struct device_attribute *attr, char *buf)
306{
307	struct srom_dev *srom = dev_get_drvdata(dev);
308	return sprintf(buf, "%u\n", srom->total_size);
309}
310
311static ssize_t sector_show(struct device *dev,
312			   struct device_attribute *attr, char *buf)
313{
314	struct srom_dev *srom = dev_get_drvdata(dev);
315	return sprintf(buf, "%u\n", srom->sector_size);
316}
317
318static ssize_t page_show(struct device *dev,
319			 struct device_attribute *attr, char *buf)
320{
321	struct srom_dev *srom = dev_get_drvdata(dev);
322	return sprintf(buf, "%u\n", srom->page_size);
323}
324
325static struct device_attribute srom_dev_attrs[] = {
326	__ATTR(total_size, S_IRUGO, total_show, NULL),
327	__ATTR(sector_size, S_IRUGO, sector_show, NULL),
328	__ATTR(page_size, S_IRUGO, page_show, NULL),
329	__ATTR_NULL
330};
331
332static char *srom_devnode(struct device *dev, mode_t *mode)
333{
334	*mode = S_IRUGO | S_IWUSR;
335	return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
336}
337
338/*
339 * The fops
340 */
341static const struct file_operations srom_fops = {
342	.owner =     THIS_MODULE,
343	.llseek =    srom_llseek,
344	.read =	     srom_read,
345	.write =     srom_write,
346	.open =	     srom_open,
347	.release =   srom_release,
348};
349
350/**
351 * srom_setup_minor() - Initialize per-minor information.
352 * @srom: Per-device SROM state.
353 * @index: Device to set up.
354 */
355static int srom_setup_minor(struct srom_dev *srom, int index)
356{
357	struct device *dev;
358	int devhdl = srom->hv_devhdl;
359
360	mutex_init(&srom->lock);
361
362	if (_srom_read(devhdl, &srom->total_size,
363		       SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
364		return -EIO;
365	if (_srom_read(devhdl, &srom->sector_size,
366		       SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
367		return -EIO;
368	if (_srom_read(devhdl, &srom->page_size,
369		       SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
370		return -EIO;
371
372	dev = device_create(srom_class, &platform_bus,
373			    MKDEV(srom_major, index), srom, "%d", index);
374	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
375}
376
377/** srom_init() - Initialize the driver's module. */
378static int srom_init(void)
379{
380	int result, i;
381	dev_t dev = MKDEV(srom_major, 0);
382
383	/*
384	 * Start with a plausible number of partitions; the krealloc() call
385	 * below will yield about log(srom_devs) additional allocations.
386	 */
387	srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL);
388
389	/* Discover the number of srom partitions. */
390	for (i = 0; ; i++) {
391		int devhdl;
392		char buf[20];
393		struct srom_dev *new_srom_devices =
394			krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
395				 GFP_KERNEL | __GFP_ZERO);
396		if (!new_srom_devices) {
397			result = -ENOMEM;
398			goto fail_mem;
399		}
400		srom_devices = new_srom_devices;
401		sprintf(buf, "srom/0/%d", i);
402		devhdl = hv_dev_open((HV_VirtAddr)buf, 0);
403		if (devhdl < 0) {
404			if (devhdl != HV_ENODEV)
405				pr_notice("srom/%d: hv_dev_open failed: %d.\n",
406					  i, devhdl);
407			break;
408		}
409		srom_devices[i].hv_devhdl = devhdl;
410	}
411	srom_devs = i;
412
413	/* Bail out early if we have no partitions at all. */
414	if (srom_devs == 0) {
415		result = -ENODEV;
416		goto fail_mem;
417	}
418
419	/* Register our major, and accept a dynamic number. */
420	if (srom_major)
421		result = register_chrdev_region(dev, srom_devs, "srom");
422	else {
423		result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
424		srom_major = MAJOR(dev);
425	}
426	if (result < 0)
427		goto fail_mem;
428
429	/* Register a character device. */
430	cdev_init(&srom_cdev, &srom_fops);
431	srom_cdev.owner = THIS_MODULE;
432	srom_cdev.ops = &srom_fops;
433	result = cdev_add(&srom_cdev, dev, srom_devs);
434	if (result < 0)
435		goto fail_chrdev;
436
437	/* Create a sysfs class. */
438	srom_class = class_create(THIS_MODULE, "srom");
439	if (IS_ERR(srom_class)) {
440		result = PTR_ERR(srom_class);
441		goto fail_cdev;
442	}
443	srom_class->dev_attrs = srom_dev_attrs;
444	srom_class->devnode = srom_devnode;
445
446	/* Do per-partition initialization */
447	for (i = 0; i < srom_devs; i++) {
448		result = srom_setup_minor(srom_devices + i, i);
449		if (result < 0)
450			goto fail_class;
451	}
452
453	return 0;
454
455fail_class:
456	for (i = 0; i < srom_devs; i++)
457		device_destroy(srom_class, MKDEV(srom_major, i));
458	class_destroy(srom_class);
459fail_cdev:
460	cdev_del(&srom_cdev);
461fail_chrdev:
462	unregister_chrdev_region(dev, srom_devs);
463fail_mem:
464	kfree(srom_devices);
465	return result;
466}
467
468/** srom_cleanup() - Clean up the driver's module. */
469static void srom_cleanup(void)
470{
471	int i;
472	for (i = 0; i < srom_devs; i++)
473		device_destroy(srom_class, MKDEV(srom_major, i));
474	class_destroy(srom_class);
475	cdev_del(&srom_cdev);
476	unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
477	kfree(srom_devices);
478}
479
480module_init(srom_init);
481module_exit(srom_cleanup);
482