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/kernel.h> /* printk() */
24 #include <linux/slab.h> /* kmalloc() */
25 #include <linux/fs.h> /* everything... */
26 #include <linux/errno.h> /* error codes */
27 #include <linux/types.h> /* size_t */
28 #include <linux/proc_fs.h>
29 #include <linux/fcntl.h> /* O_ACCMODE */
30 #include <linux/aio.h>
31 #include <linux/pagemap.h>
32 #include <linux/hugetlb.h>
33 #include <linux/uaccess.h>
34 #include <linux/platform_device.h>
35 #include <hv/hypervisor.h>
36 #include <linux/ioctl.h>
37 #include <linux/cdev.h>
38 #include <linux/delay.h>
39 #include <hv/drv_srom_intf.h>
40
41 /*
42 * Size of our hypervisor I/O requests. We break up large transfers
43 * so that we don't spend large uninterrupted spans of time in the
44 * hypervisor. Erasing an SROM sector takes a significant fraction of
45 * a second, so if we allowed the user to, say, do one I/O to write the
46 * entire ROM, we'd get soft lockup timeouts, or worse.
47 */
48 #define SROM_CHUNK_SIZE ((size_t)4096)
49
50 /*
51 * When hypervisor is busy (e.g. erasing), poll the status periodically.
52 */
53
54 /*
55 * Interval to poll the state in msec
56 */
57 #define SROM_WAIT_TRY_INTERVAL 20
58
59 /*
60 * Maximum times to poll the state
61 */
62 #define SROM_MAX_WAIT_TRY_TIMES 1000
63
64 struct srom_dev {
65 int hv_devhdl; /* Handle for hypervisor device */
66 u32 total_size; /* Size of this device */
67 u32 sector_size; /* Size of a sector */
68 u32 page_size; /* Size of a page */
69 struct mutex lock; /* Allow only one accessor at a time */
70 };
71
72 static int srom_major; /* Dynamic major by default */
73 module_param(srom_major, int, 0);
74 MODULE_AUTHOR("Tilera Corporation");
75 MODULE_LICENSE("GPL");
76
77 static int srom_devs; /* Number of SROM partitions */
78 static struct cdev srom_cdev;
79 static struct platform_device *srom_parent;
80 static struct class *srom_class;
81 static struct srom_dev *srom_devices;
82
83 /*
84 * Handle calling the hypervisor and managing EAGAIN/EBUSY.
85 */
86
_srom_read(int hv_devhdl,void * buf,loff_t off,size_t count)87 static 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
_srom_write(int hv_devhdl,const void * buf,loff_t off,size_t count)107 static 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 */
srom_open(struct inode * inode,struct file * filp)134 static 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 */
srom_release(struct inode * inode,struct file * filp)148 static 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 */
srom_read(struct file * filp,char __user * buf,size_t count,loff_t * f_pos)174 static 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 (retval == 0)
199 retval = hv_retval;
200 break;
201 }
202
203 if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
204 retval = -EFAULT;
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 */
srom_write(struct file * filp,const char __user * buf,size_t count,loff_t * f_pos)229 static 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. */
srom_llseek(struct file * file,loff_t offset,int origin)276 loff_t srom_llseek(struct file *file, loff_t offset, int origin)
277 {
278 struct srom_dev *srom = file->private_data;
279 return fixed_size_llseek(file, offset, origin, srom->total_size);
280 }
281
total_size_show(struct device * dev,struct device_attribute * attr,char * buf)282 static ssize_t total_size_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 static DEVICE_ATTR_RO(total_size);
289
sector_size_show(struct device * dev,struct device_attribute * attr,char * buf)290 static ssize_t sector_size_show(struct device *dev,
291 struct device_attribute *attr, char *buf)
292 {
293 struct srom_dev *srom = dev_get_drvdata(dev);
294 return sprintf(buf, "%u\n", srom->sector_size);
295 }
296 static DEVICE_ATTR_RO(sector_size);
297
page_size_show(struct device * dev,struct device_attribute * attr,char * buf)298 static ssize_t page_size_show(struct device *dev,
299 struct device_attribute *attr, char *buf)
300 {
301 struct srom_dev *srom = dev_get_drvdata(dev);
302 return sprintf(buf, "%u\n", srom->page_size);
303 }
304 static DEVICE_ATTR_RO(page_size);
305
306 static struct attribute *srom_dev_attrs[] = {
307 &dev_attr_total_size.attr,
308 &dev_attr_sector_size.attr,
309 &dev_attr_page_size.attr,
310 NULL,
311 };
312 ATTRIBUTE_GROUPS(srom_dev);
313
srom_devnode(struct device * dev,umode_t * mode)314 static char *srom_devnode(struct device *dev, umode_t *mode)
315 {
316 *mode = S_IRUGO | S_IWUSR;
317 return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
318 }
319
320 /*
321 * The fops
322 */
323 static const struct file_operations srom_fops = {
324 .owner = THIS_MODULE,
325 .llseek = srom_llseek,
326 .read = srom_read,
327 .write = srom_write,
328 .open = srom_open,
329 .release = srom_release,
330 };
331
332 /**
333 * srom_setup_minor() - Initialize per-minor information.
334 * @srom: Per-device SROM state.
335 * @index: Device to set up.
336 */
srom_setup_minor(struct srom_dev * srom,int index)337 static int srom_setup_minor(struct srom_dev *srom, int index)
338 {
339 struct device *dev;
340 int devhdl = srom->hv_devhdl;
341
342 mutex_init(&srom->lock);
343
344 if (_srom_read(devhdl, &srom->total_size,
345 SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
346 return -EIO;
347 if (_srom_read(devhdl, &srom->sector_size,
348 SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
349 return -EIO;
350 if (_srom_read(devhdl, &srom->page_size,
351 SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
352 return -EIO;
353
354 dev = device_create(srom_class, &srom_parent->dev,
355 MKDEV(srom_major, index), srom, "%d", index);
356 return PTR_ERR_OR_ZERO(dev);
357 }
358
359 /** srom_init() - Initialize the driver's module. */
srom_init(void)360 static int srom_init(void)
361 {
362 int result, i;
363 dev_t dev = MKDEV(srom_major, 0);
364
365 /*
366 * Start with a plausible number of partitions; the krealloc() call
367 * below will yield about log(srom_devs) additional allocations.
368 */
369 srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL);
370
371 /* Discover the number of srom partitions. */
372 for (i = 0; ; i++) {
373 int devhdl;
374 char buf[20];
375 struct srom_dev *new_srom_devices =
376 krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
377 GFP_KERNEL | __GFP_ZERO);
378 if (!new_srom_devices) {
379 result = -ENOMEM;
380 goto fail_mem;
381 }
382 srom_devices = new_srom_devices;
383 sprintf(buf, "srom/0/%d", i);
384 devhdl = hv_dev_open((HV_VirtAddr)buf, 0);
385 if (devhdl < 0) {
386 if (devhdl != HV_ENODEV)
387 pr_notice("srom/%d: hv_dev_open failed: %d.\n",
388 i, devhdl);
389 break;
390 }
391 srom_devices[i].hv_devhdl = devhdl;
392 }
393 srom_devs = i;
394
395 /* Bail out early if we have no partitions at all. */
396 if (srom_devs == 0) {
397 result = -ENODEV;
398 goto fail_mem;
399 }
400
401 /* Register our major, and accept a dynamic number. */
402 if (srom_major)
403 result = register_chrdev_region(dev, srom_devs, "srom");
404 else {
405 result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
406 srom_major = MAJOR(dev);
407 }
408 if (result < 0)
409 goto fail_mem;
410
411 /* Register a character device. */
412 cdev_init(&srom_cdev, &srom_fops);
413 srom_cdev.owner = THIS_MODULE;
414 srom_cdev.ops = &srom_fops;
415 result = cdev_add(&srom_cdev, dev, srom_devs);
416 if (result < 0)
417 goto fail_chrdev;
418
419 /* Create a parent device */
420 srom_parent = platform_device_register_simple("srom", -1, NULL, 0);
421 if (IS_ERR(srom_parent)) {
422 result = PTR_ERR(srom_parent);
423 goto fail_pdev;
424 }
425
426 /* Create a sysfs class. */
427 srom_class = class_create(THIS_MODULE, "srom");
428 if (IS_ERR(srom_class)) {
429 result = PTR_ERR(srom_class);
430 goto fail_cdev;
431 }
432 srom_class->dev_groups = srom_dev_groups;
433 srom_class->devnode = srom_devnode;
434
435 /* Do per-partition initialization */
436 for (i = 0; i < srom_devs; i++) {
437 result = srom_setup_minor(srom_devices + i, i);
438 if (result < 0)
439 goto fail_class;
440 }
441
442 return 0;
443
444 fail_class:
445 for (i = 0; i < srom_devs; i++)
446 device_destroy(srom_class, MKDEV(srom_major, i));
447 class_destroy(srom_class);
448 fail_cdev:
449 platform_device_unregister(srom_parent);
450 fail_pdev:
451 cdev_del(&srom_cdev);
452 fail_chrdev:
453 unregister_chrdev_region(dev, srom_devs);
454 fail_mem:
455 kfree(srom_devices);
456 return result;
457 }
458
459 /** srom_cleanup() - Clean up the driver's module. */
srom_cleanup(void)460 static void srom_cleanup(void)
461 {
462 int i;
463 for (i = 0; i < srom_devs; i++)
464 device_destroy(srom_class, MKDEV(srom_major, i));
465 class_destroy(srom_class);
466 cdev_del(&srom_cdev);
467 platform_device_unregister(srom_parent);
468 unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
469 kfree(srom_devices);
470 }
471
472 module_init(srom_init);
473 module_exit(srom_cleanup);
474