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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,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200158 .llseek = noop_llseek,
Sonny Raofe9e8d52008-07-08 15:45:11 +1000159};
160
161static void bsr_cleanup_devs(void)
162{
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000163 struct bsr_dev *cur, *n;
164
165 list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
Sonny Raofe9e8d52008-07-08 15:45:11 +1000166 if (cur->bsr_device) {
167 cdev_del(&cur->bsr_cdev);
168 device_del(cur->bsr_device);
169 }
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000170 list_del(&cur->bsr_list);
171 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000172 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000173}
174
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000175static int bsr_add_node(struct device_node *bn)
Sonny Raofe9e8d52008-07-08 15:45:11 +1000176{
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000177 int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000178 const u32 *bsr_stride;
179 const u32 *bsr_bytes;
180 unsigned i;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000181 int ret = -ENODEV;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000182
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");
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000189 return ret;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000190 }
191
192 num_bsr_devs = bsr_bytes_len / sizeof(u32);
193
Sonny Raofe9e8d52008-07-08 15:45:11 +1000194 for (i = 0 ; i < num_bsr_devs; i++) {
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000195 struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
196 GFP_KERNEL);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000197 struct resource res;
198 int result;
199
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000200 if (!cur) {
201 printk(KERN_ERR "Unable to alloc bsr dev\n");
202 ret = -ENOMEM;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000203 goto out_err;
204 }
205
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000206 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;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000214 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];
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000218 cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000219
Sonny Rao04a85d12009-06-18 15:13:04 +0000220 /* 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
Sonny Raofe9e8d52008-07-08 15:45:11 +1000225 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;
Sonny Raoe4031d52009-06-18 15:14:36 +0000238 case 4096:
239 cur->bsr_type = BSR_4096;
240 break;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000241 default:
242 cur->bsr_type = BSR_UNKNOWN;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000243 }
244
245 cur->bsr_num = bsr_types[cur->bsr_type];
Sonny Raofe9e8d52008-07-08 15:45:11 +1000246 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);
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000251 if (result) {
252 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000253 goto out_err;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000254 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000255
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700256 cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
257 cur, cur->bsr_name);
Jani Nikula30c96ce52010-03-11 18:15:53 +0200258 if (IS_ERR(cur->bsr_device)) {
Sonny Raofe9e8d52008-07-08 15:45:11 +1000259 printk(KERN_ERR "device_create failed for %s\n",
260 cur->bsr_name);
261 cdev_del(&cur->bsr_cdev);
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000262 kfree(cur);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000263 goto out_err;
264 }
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000265
266 bsr_types[cur->bsr_type] = cur->bsr_num + 1;
267 list_add_tail(&cur->bsr_list, &bsr_devs);
Sonny Raofe9e8d52008-07-08 15:45:11 +1000268 }
269
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000270 total_bsr_devs += num_bsr_devs;
271
Sonny Raofe9e8d52008-07-08 15:45:11 +1000272 return 0;
273
274 out_err:
275
276 bsr_cleanup_devs();
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000277 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;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000293}
294
295static int __init bsr_init(void)
296{
297 struct device_node *np;
298 dev_t bsr_dev = MKDEV(bsr_major, 0);
299 int ret = -ENODEV;
300 int result;
301
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000302 np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
Sonny Raofe9e8d52008-07-08 15:45:11 +1000303 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
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000320 if ((ret = bsr_create_devs(np)) < 0) {
321 np = NULL;
Sonny Raofe9e8d52008-07-08 15:45:11 +1000322 goto out_err_3;
Sonny Raoa0e2f9f2008-11-09 14:15:11 +0000323 }
Sonny Raofe9e8d52008-07-08 15:45:11 +1000324
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>");