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Chris Metcalfdbcb4a12011-06-10 13:07:48 -04001/*
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);
Chris Metcalf16418bb2012-03-30 19:03:04 -0400197 if (hv_retval <= 0) {
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400198 if (retval == 0)
199 retval = hv_retval;
200 break;
201 }
202
Chris Metcalf16418bb2012-03-30 19:03:04 -0400203 if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
204 retval = -EFAULT;
205 break;
206 }
207
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400208 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. */
Al Viro914961a2013-06-23 12:43:48 +0400276loff_t srom_llseek(struct file *file, loff_t offset, int origin)
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400277{
Al Viro914961a2013-06-23 12:43:48 +0400278 struct srom_dev *srom = file->private_data;
279 return fixed_size_llseek(file, offset, origin, srom->total_size);
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400280}
281
282static ssize_t total_show(struct device *dev,
283 struct device_attribute *attr, char *buf)
284{
285 struct srom_dev *srom = dev_get_drvdata(dev);
286 return sprintf(buf, "%u\n", srom->total_size);
287}
288
289static ssize_t sector_show(struct device *dev,
290 struct device_attribute *attr, char *buf)
291{
292 struct srom_dev *srom = dev_get_drvdata(dev);
293 return sprintf(buf, "%u\n", srom->sector_size);
294}
295
296static ssize_t page_show(struct device *dev,
297 struct device_attribute *attr, char *buf)
298{
299 struct srom_dev *srom = dev_get_drvdata(dev);
300 return sprintf(buf, "%u\n", srom->page_size);
301}
302
303static struct device_attribute srom_dev_attrs[] = {
304 __ATTR(total_size, S_IRUGO, total_show, NULL),
305 __ATTR(sector_size, S_IRUGO, sector_show, NULL),
306 __ATTR(page_size, S_IRUGO, page_show, NULL),
307 __ATTR_NULL
308};
309
Al Viro2c9ede52011-07-23 20:24:48 -0400310static char *srom_devnode(struct device *dev, umode_t *mode)
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400311{
312 *mode = S_IRUGO | S_IWUSR;
313 return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
314}
315
316/*
317 * The fops
318 */
319static const struct file_operations srom_fops = {
320 .owner = THIS_MODULE,
321 .llseek = srom_llseek,
322 .read = srom_read,
323 .write = srom_write,
324 .open = srom_open,
325 .release = srom_release,
326};
327
328/**
329 * srom_setup_minor() - Initialize per-minor information.
330 * @srom: Per-device SROM state.
331 * @index: Device to set up.
332 */
333static int srom_setup_minor(struct srom_dev *srom, int index)
334{
335 struct device *dev;
336 int devhdl = srom->hv_devhdl;
337
338 mutex_init(&srom->lock);
339
340 if (_srom_read(devhdl, &srom->total_size,
341 SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
342 return -EIO;
343 if (_srom_read(devhdl, &srom->sector_size,
344 SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
345 return -EIO;
346 if (_srom_read(devhdl, &srom->page_size,
347 SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
348 return -EIO;
349
350 dev = device_create(srom_class, &platform_bus,
351 MKDEV(srom_major, index), srom, "%d", index);
Alexandru Gheorghiu275b5d22013-03-16 16:19:51 +0200352 return PTR_RET(dev);
Chris Metcalfdbcb4a12011-06-10 13:07:48 -0400353}
354
355/** srom_init() - Initialize the driver's module. */
356static int srom_init(void)
357{
358 int result, i;
359 dev_t dev = MKDEV(srom_major, 0);
360
361 /*
362 * Start with a plausible number of partitions; the krealloc() call
363 * below will yield about log(srom_devs) additional allocations.
364 */
365 srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL);
366
367 /* Discover the number of srom partitions. */
368 for (i = 0; ; i++) {
369 int devhdl;
370 char buf[20];
371 struct srom_dev *new_srom_devices =
372 krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
373 GFP_KERNEL | __GFP_ZERO);
374 if (!new_srom_devices) {
375 result = -ENOMEM;
376 goto fail_mem;
377 }
378 srom_devices = new_srom_devices;
379 sprintf(buf, "srom/0/%d", i);
380 devhdl = hv_dev_open((HV_VirtAddr)buf, 0);
381 if (devhdl < 0) {
382 if (devhdl != HV_ENODEV)
383 pr_notice("srom/%d: hv_dev_open failed: %d.\n",
384 i, devhdl);
385 break;
386 }
387 srom_devices[i].hv_devhdl = devhdl;
388 }
389 srom_devs = i;
390
391 /* Bail out early if we have no partitions at all. */
392 if (srom_devs == 0) {
393 result = -ENODEV;
394 goto fail_mem;
395 }
396
397 /* Register our major, and accept a dynamic number. */
398 if (srom_major)
399 result = register_chrdev_region(dev, srom_devs, "srom");
400 else {
401 result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
402 srom_major = MAJOR(dev);
403 }
404 if (result < 0)
405 goto fail_mem;
406
407 /* Register a character device. */
408 cdev_init(&srom_cdev, &srom_fops);
409 srom_cdev.owner = THIS_MODULE;
410 srom_cdev.ops = &srom_fops;
411 result = cdev_add(&srom_cdev, dev, srom_devs);
412 if (result < 0)
413 goto fail_chrdev;
414
415 /* Create a sysfs class. */
416 srom_class = class_create(THIS_MODULE, "srom");
417 if (IS_ERR(srom_class)) {
418 result = PTR_ERR(srom_class);
419 goto fail_cdev;
420 }
421 srom_class->dev_attrs = srom_dev_attrs;
422 srom_class->devnode = srom_devnode;
423
424 /* Do per-partition initialization */
425 for (i = 0; i < srom_devs; i++) {
426 result = srom_setup_minor(srom_devices + i, i);
427 if (result < 0)
428 goto fail_class;
429 }
430
431 return 0;
432
433fail_class:
434 for (i = 0; i < srom_devs; i++)
435 device_destroy(srom_class, MKDEV(srom_major, i));
436 class_destroy(srom_class);
437fail_cdev:
438 cdev_del(&srom_cdev);
439fail_chrdev:
440 unregister_chrdev_region(dev, srom_devs);
441fail_mem:
442 kfree(srom_devices);
443 return result;
444}
445
446/** srom_cleanup() - Clean up the driver's module. */
447static void srom_cleanup(void)
448{
449 int i;
450 for (i = 0; i < srom_devs; i++)
451 device_destroy(srom_class, MKDEV(srom_major, i));
452 class_destroy(srom_class);
453 cdev_del(&srom_cdev);
454 unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
455 kfree(srom_devices);
456}
457
458module_init(srom_init);
459module_exit(srom_cleanup);