Root/drivers/char/tile-srom.c

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 (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 */
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, umode_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

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive