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Sonny Raofe9e8d52008-07-08 15:45:11 +10001/* 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>
Grant Likely22ae7822010-07-29 11:49:01 -060026#include <linux/fs.h>
Sonny Raofe9e8d52008-07-08 15:45:11 +100027#include <linux/module.h>
28#include <linux/cdev.h>
29#include <linux/list.h>
30#include <linux/mm.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090031#include <linux/slab.h>
Sonny Rao04a85d12009-06-18 15:13:04 +000032#include <asm/pgtable.h>
Sonny Raofe9e8d52008-07-08 15:45:11 +100033#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
Sonny Raoa0e2f9f2008-11-09 14:15:11 +000066 struct list_head bsr_list;
67
Sonny Raofe9e8d52008-07-08 15:45:11 +100068 dev_t bsr_dev;
69 struct cdev bsr_cdev;
70 struct device *bsr_device;
71 char bsr_name[32];
72
73};
74
Sonny Raoa0e2f9f2008-11-09 14:15:11 +000075static unsigned total_bsr_devs;
76static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
Sonny Raofe9e8d52008-07-08 15:45:11 +100077static struct class *bsr_class;
78static int bsr_major;
79
80enum {
Sonny Raoe4031d52009-06-18 15:14:36 +000081 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,
Sonny Raofe9e8d52008-07-08 15:45:11 +100088};
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);
Stephen Rothwell19015152009-01-06 14:28:48 +0000110 return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000111}
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;
Sonny Rao04a85d12009-06-18 15:13:04 +0000124 int ret;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000125
Sonny Raofe9e8d52008-07-08 15:45:11 +1000126 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
127
Sonny Rao04a85d12009-06-18 15:13:04 +0000128 /* 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)
Sonny Raofe9e8d52008-07-08 15:45:11 +1000140 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
Tobias Klauser27157a72009-02-09 22:01:08 +0100154static const struct file_operations bsr_fops = {
Sonny Raofe9e8d52008-07-08 15:45:11 +1000155 .owner = THIS_MODULE,
156 .mmap = bsr_mmap,
157 .open = bsr_open,
158};
159
160static void bsr_cleanup_devs(void)
161{
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000162 struct bsr_dev *cur, *n;
163
164 list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
Sonny Raofe9e8d52008-07-08 15:45:11 +1000165 if (cur->bsr_device) {
166 cdev_del(&cur->bsr_cdev);
167 device_del(cur->bsr_device);
168 }
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000169 list_del(&cur->bsr_list);
170 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000171 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000172}
173
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000174static int bsr_add_node(struct device_node *bn)
Sonny Raofe9e8d52008-07-08 15:45:11 +1000175{
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000176 int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000177 const u32 *bsr_stride;
178 const u32 *bsr_bytes;
179 unsigned i;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000180 int ret = -ENODEV;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000181
182 bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
183 bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
184
185 if (!bsr_stride || !bsr_bytes ||
186 (bsr_stride_len != bsr_bytes_len)) {
187 printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000188 return ret;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000189 }
190
191 num_bsr_devs = bsr_bytes_len / sizeof(u32);
192
Sonny Raofe9e8d52008-07-08 15:45:11 +1000193 for (i = 0 ; i < num_bsr_devs; i++) {
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000194 struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
195 GFP_KERNEL);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000196 struct resource res;
197 int result;
198
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000199 if (!cur) {
200 printk(KERN_ERR "Unable to alloc bsr dev\n");
201 ret = -ENOMEM;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000202 goto out_err;
203 }
204
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000205 result = of_address_to_resource(bn, i, &res);
206 if (result < 0) {
207 printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
208 kfree(cur);
209 continue;
210 }
211
212 cur->bsr_minor = i + total_bsr_devs;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000213 cur->bsr_addr = res.start;
214 cur->bsr_len = res.end - res.start + 1;
215 cur->bsr_bytes = bsr_bytes[i];
216 cur->bsr_stride = bsr_stride[i];
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000217 cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000218
Sonny Rao04a85d12009-06-18 15:13:04 +0000219 /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
220 /* we can only map 4k of it, so only advertise the 4k in sysfs */
221 if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
222 cur->bsr_len = 4096;
223
Sonny Raofe9e8d52008-07-08 15:45:11 +1000224 switch(cur->bsr_bytes) {
225 case 8:
226 cur->bsr_type = BSR_8;
227 break;
228 case 16:
229 cur->bsr_type = BSR_16;
230 break;
231 case 64:
232 cur->bsr_type = BSR_64;
233 break;
234 case 128:
235 cur->bsr_type = BSR_128;
236 break;
Sonny Raoe4031d52009-06-18 15:14:36 +0000237 case 4096:
238 cur->bsr_type = BSR_4096;
239 break;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000240 default:
241 cur->bsr_type = BSR_UNKNOWN;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000242 }
243
244 cur->bsr_num = bsr_types[cur->bsr_type];
Sonny Raofe9e8d52008-07-08 15:45:11 +1000245 snprintf(cur->bsr_name, 32, "bsr%d_%d",
246 cur->bsr_bytes, cur->bsr_num);
247
248 cdev_init(&cur->bsr_cdev, &bsr_fops);
249 result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000250 if (result) {
251 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000252 goto out_err;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000253 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000254
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700255 cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
256 cur, cur->bsr_name);
Jani Nikula30c96ce52010-03-11 18:15:53 +0200257 if (IS_ERR(cur->bsr_device)) {
Sonny Raofe9e8d52008-07-08 15:45:11 +1000258 printk(KERN_ERR "device_create failed for %s\n",
259 cur->bsr_name);
260 cdev_del(&cur->bsr_cdev);
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000261 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000262 goto out_err;
263 }
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000264
265 bsr_types[cur->bsr_type] = cur->bsr_num + 1;
266 list_add_tail(&cur->bsr_list, &bsr_devs);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000267 }
268
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000269 total_bsr_devs += num_bsr_devs;
270
Sonny Raofe9e8d52008-07-08 15:45:11 +1000271 return 0;
272
273 out_err:
274
275 bsr_cleanup_devs();
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000276 return ret;
277}
278
279static int bsr_create_devs(struct device_node *bn)
280{
281 int ret;
282
283 while (bn) {
284 ret = bsr_add_node(bn);
285 if (ret) {
286 of_node_put(bn);
287 return ret;
288 }
289 bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
290 }
291 return 0;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000292}
293
294static int __init bsr_init(void)
295{
296 struct device_node *np;
297 dev_t bsr_dev = MKDEV(bsr_major, 0);
298 int ret = -ENODEV;
299 int result;
300
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000301 np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
Sonny Raofe9e8d52008-07-08 15:45:11 +1000302 if (!np)
303 goto out_err;
304
305 bsr_class = class_create(THIS_MODULE, "bsr");
306 if (IS_ERR(bsr_class)) {
307 printk(KERN_ERR "class_create() failed for bsr_class\n");
308 goto out_err_1;
309 }
310 bsr_class->dev_attrs = bsr_dev_attrs;
311
312 result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
313 bsr_major = MAJOR(bsr_dev);
314 if (result < 0) {
315 printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
316 goto out_err_2;
317 }
318
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000319 if ((ret = bsr_create_devs(np)) < 0) {
320 np = NULL;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000321 goto out_err_3;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000322 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000323
324 return 0;
325
326 out_err_3:
327 unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
328
329 out_err_2:
330 class_destroy(bsr_class);
331
332 out_err_1:
333 of_node_put(np);
334
335 out_err:
336
337 return ret;
338}
339
340static void __exit bsr_exit(void)
341{
342
343 bsr_cleanup_devs();
344
345 if (bsr_class)
346 class_destroy(bsr_class);
347
348 if (bsr_major)
349 unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
350}
351
352module_init(bsr_init);
353module_exit(bsr_exit);
354MODULE_LICENSE("GPL");
355MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");