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/drivers/char/bsr.c

https://bitbucket.org/ndreys/linux-sunxi
C | 356 lines | 254 code | 60 blank | 42 comment | 25 complexity | 12bfa48039098aadb949a28c278120d5 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/* IBM POWER Barrier Synchronization Register Driver
  2 *
  3 * Copyright IBM Corporation 2008
  4 *
  5 * Author: Sonny Rao <sonnyrao@us.ibm.com>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License as published by
  9 * the Free Software Foundation; either version 2 of the License, or
 10 * (at your option) any later version.
 11 *
 12 * This program is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15 * GNU General Public License for more details.
 16 *
 17 * You should have received a copy of the GNU General Public License
 18 * along with this program; if not, write to the Free Software
 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 20 */
 21
 22#include <linux/kernel.h>
 23#include <linux/of.h>
 24#include <linux/of_device.h>
 25#include <linux/of_platform.h>
 26#include <linux/fs.h>
 27#include <linux/module.h>
 28#include <linux/cdev.h>
 29#include <linux/list.h>
 30#include <linux/mm.h>
 31#include <linux/slab.h>
 32#include <asm/pgtable.h>
 33#include <asm/io.h>
 34
 35/*
 36 This driver exposes a special register which can be used for fast
 37 synchronization across a large SMP machine.  The hardware is exposed
 38 as an array of bytes where each process will write to one of the bytes to
 39 indicate it has finished the current stage and this update is broadcast to
 40 all processors without having to bounce a cacheline between them. In
 41 POWER5 and POWER6 there is one of these registers per SMP,  but it is
 42 presented in two forms; first, it is given as a whole and then as a number
 43 of smaller registers which alias to parts of the single whole register.
 44 This can potentially allow multiple groups of processes to each have their
 45 own private synchronization device.
 46
 47 Note that this hardware *must* be written to using *only* single byte writes.
 48 It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
 49 this region is treated as cache-inhibited  processes should also use a
 50 full sync before and after writing to the BSR to ensure all stores and
 51 the BSR update have made it to all chips in the system
 52*/
 53
 54/* This is arbitrary number, up to Power6 it's been 17 or fewer  */
 55#define BSR_MAX_DEVS (32)
 56
 57struct bsr_dev {
 58	u64      bsr_addr;     /* Real address */
 59	u64      bsr_len;      /* length of mem region we can map */
 60	unsigned bsr_bytes;    /* size of the BSR reg itself */
 61	unsigned bsr_stride;   /* interval at which BSR repeats in the page */
 62	unsigned bsr_type;     /* maps to enum below */
 63	unsigned bsr_num;      /* bsr id number for its type */
 64	int      bsr_minor;
 65
 66	struct list_head bsr_list;
 67
 68	dev_t    bsr_dev;
 69	struct cdev bsr_cdev;
 70	struct device *bsr_device;
 71	char     bsr_name[32];
 72
 73};
 74
 75static unsigned total_bsr_devs;
 76static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
 77static struct class *bsr_class;
 78static int bsr_major;
 79
 80enum {
 81	BSR_8    = 0,
 82	BSR_16   = 1,
 83	BSR_64   = 2,
 84	BSR_128  = 3,
 85	BSR_4096 = 4,
 86	BSR_UNKNOWN = 5,
 87	BSR_MAX  = 6,
 88};
 89
 90static unsigned bsr_types[BSR_MAX];
 91
 92static ssize_t
 93bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf)
 94{
 95	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
 96	return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
 97}
 98
 99static ssize_t
100bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf)
101{
102	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
103	return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
104}
105
106static ssize_t
107bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf)
108{
109	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
110	return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
111}
112
113static struct device_attribute bsr_dev_attrs[] = {
114	__ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL),
115	__ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL),
116	__ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL),
117	__ATTR_NULL
118};
119
120static int bsr_mmap(struct file *filp, struct vm_area_struct *vma)
121{
122	unsigned long size   = vma->vm_end - vma->vm_start;
123	struct bsr_dev *dev = filp->private_data;
124	int ret;
125
126	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
127
128	/* check for the case of a small BSR device and map one 4k page for it*/
129	if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE)
130		ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12,
131				   vma->vm_page_prot);
132	else if (size <= dev->bsr_len)
133		ret = io_remap_pfn_range(vma, vma->vm_start,
134					 dev->bsr_addr >> PAGE_SHIFT,
135					 size, vma->vm_page_prot);
136	else
137		return -EINVAL;
138
139	if (ret)
140		return -EAGAIN;
141
142	return 0;
143}
144
145static int bsr_open(struct inode * inode, struct file * filp)
146{
147	struct cdev *cdev = inode->i_cdev;
148	struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);
149
150	filp->private_data = dev;
151	return 0;
152}
153
154static const struct file_operations bsr_fops = {
155	.owner = THIS_MODULE,
156	.mmap  = bsr_mmap,
157	.open  = bsr_open,
158	.llseek = noop_llseek,
159};
160
161static void bsr_cleanup_devs(void)
162{
163	struct bsr_dev *cur, *n;
164
165	list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
166		if (cur->bsr_device) {
167			cdev_del(&cur->bsr_cdev);
168			device_del(cur->bsr_device);
169		}
170		list_del(&cur->bsr_list);
171		kfree(cur);
172	}
173}
174
175static int bsr_add_node(struct device_node *bn)
176{
177	int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
178	const u32 *bsr_stride;
179	const u32 *bsr_bytes;
180	unsigned i;
181	int ret = -ENODEV;
182
183	bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
184	bsr_bytes  = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
185
186	if (!bsr_stride || !bsr_bytes ||
187	    (bsr_stride_len != bsr_bytes_len)) {
188		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
189		return ret;
190	}
191
192	num_bsr_devs = bsr_bytes_len / sizeof(u32);
193
194	for (i = 0 ; i < num_bsr_devs; i++) {
195		struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
196					      GFP_KERNEL);
197		struct resource res;
198		int result;
199
200		if (!cur) {
201			printk(KERN_ERR "Unable to alloc bsr dev\n");
202			ret = -ENOMEM;
203			goto out_err;
204		}
205
206		result = of_address_to_resource(bn, i, &res);
207		if (result < 0) {
208			printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
209			kfree(cur);
210			continue;
211		}
212
213		cur->bsr_minor  = i + total_bsr_devs;
214		cur->bsr_addr   = res.start;
215		cur->bsr_len    = res.end - res.start + 1;
216		cur->bsr_bytes  = bsr_bytes[i];
217		cur->bsr_stride = bsr_stride[i];
218		cur->bsr_dev    = MKDEV(bsr_major, i + total_bsr_devs);
219
220		/* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
221		/* we can only map 4k of it, so only advertise the 4k in sysfs */
222		if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
223			cur->bsr_len = 4096;
224
225		switch(cur->bsr_bytes) {
226		case 8:
227			cur->bsr_type = BSR_8;
228			break;
229		case 16:
230			cur->bsr_type = BSR_16;
231			break;
232		case 64:
233			cur->bsr_type = BSR_64;
234			break;
235		case 128:
236			cur->bsr_type = BSR_128;
237			break;
238		case 4096:
239			cur->bsr_type = BSR_4096;
240			break;
241		default:
242			cur->bsr_type = BSR_UNKNOWN;
243		}
244
245		cur->bsr_num = bsr_types[cur->bsr_type];
246		snprintf(cur->bsr_name, 32, "bsr%d_%d",
247			 cur->bsr_bytes, cur->bsr_num);
248
249		cdev_init(&cur->bsr_cdev, &bsr_fops);
250		result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
251		if (result) {
252			kfree(cur);
253			goto out_err;
254		}
255
256		cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
257						cur, cur->bsr_name);
258		if (IS_ERR(cur->bsr_device)) {
259			printk(KERN_ERR "device_create failed for %s\n",
260			       cur->bsr_name);
261			cdev_del(&cur->bsr_cdev);
262			kfree(cur);
263			goto out_err;
264		}
265
266		bsr_types[cur->bsr_type] = cur->bsr_num + 1;
267		list_add_tail(&cur->bsr_list, &bsr_devs);
268	}
269
270	total_bsr_devs += num_bsr_devs;
271
272	return 0;
273
274 out_err:
275
276	bsr_cleanup_devs();
277	return ret;
278}
279
280static int bsr_create_devs(struct device_node *bn)
281{
282	int ret;
283
284	while (bn) {
285		ret = bsr_add_node(bn);
286		if (ret) {
287			of_node_put(bn);
288			return ret;
289		}
290		bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
291	}
292	return 0;
293}
294
295static int __init bsr_init(void)
296{
297	struct device_node *np;
298	dev_t bsr_dev;
299	int ret = -ENODEV;
300	int result;
301
302	np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
303	if (!np)
304		goto out_err;
305
306	bsr_class = class_create(THIS_MODULE, "bsr");
307	if (IS_ERR(bsr_class)) {
308		printk(KERN_ERR "class_create() failed for bsr_class\n");
309		goto out_err_1;
310	}
311	bsr_class->dev_attrs = bsr_dev_attrs;
312
313	result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
314	bsr_major = MAJOR(bsr_dev);
315	if (result < 0) {
316		printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
317		goto out_err_2;
318	}
319
320	if ((ret = bsr_create_devs(np)) < 0) {
321		np = NULL;
322		goto out_err_3;
323	}
324
325	return 0;
326
327 out_err_3:
328	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
329
330 out_err_2:
331	class_destroy(bsr_class);
332
333 out_err_1:
334	of_node_put(np);
335
336 out_err:
337
338	return ret;
339}
340
341static void __exit  bsr_exit(void)
342{
343
344	bsr_cleanup_devs();
345
346	if (bsr_class)
347		class_destroy(bsr_class);
348
349	if (bsr_major)
350		unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
351}
352
353module_init(bsr_init);
354module_exit(bsr_exit);
355MODULE_LICENSE("GPL");
356MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");