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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 = resource_size(&res);
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>");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* IBM POWER Barrier Synchronization Register Driver
3 *
4 * Copyright IBM Corporation 2008
5 *
6 * Author: Sonny Rao <sonnyrao@us.ibm.com>
7 */
8
9#include <linux/kernel.h>
10#include <linux/of.h>
11#include <linux/of_address.h>
12#include <linux/of_device.h>
13#include <linux/of_platform.h>
14#include <linux/fs.h>
15#include <linux/module.h>
16#include <linux/cdev.h>
17#include <linux/list.h>
18#include <linux/mm.h>
19#include <linux/slab.h>
20#include <asm/pgtable.h>
21#include <asm/io.h>
22
23/*
24 This driver exposes a special register which can be used for fast
25 synchronization across a large SMP machine. The hardware is exposed
26 as an array of bytes where each process will write to one of the bytes to
27 indicate it has finished the current stage and this update is broadcast to
28 all processors without having to bounce a cacheline between them. In
29 POWER5 and POWER6 there is one of these registers per SMP, but it is
30 presented in two forms; first, it is given as a whole and then as a number
31 of smaller registers which alias to parts of the single whole register.
32 This can potentially allow multiple groups of processes to each have their
33 own private synchronization device.
34
35 Note that this hardware *must* be written to using *only* single byte writes.
36 It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
37 this region is treated as cache-inhibited processes should also use a
38 full sync before and after writing to the BSR to ensure all stores and
39 the BSR update have made it to all chips in the system
40*/
41
42/* This is arbitrary number, up to Power6 it's been 17 or fewer */
43#define BSR_MAX_DEVS (32)
44
45struct bsr_dev {
46 u64 bsr_addr; /* Real address */
47 u64 bsr_len; /* length of mem region we can map */
48 unsigned bsr_bytes; /* size of the BSR reg itself */
49 unsigned bsr_stride; /* interval at which BSR repeats in the page */
50 unsigned bsr_type; /* maps to enum below */
51 unsigned bsr_num; /* bsr id number for its type */
52 int bsr_minor;
53
54 struct list_head bsr_list;
55
56 dev_t bsr_dev;
57 struct cdev bsr_cdev;
58 struct device *bsr_device;
59 char bsr_name[32];
60
61};
62
63static unsigned total_bsr_devs;
64static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
65static struct class *bsr_class;
66static int bsr_major;
67
68enum {
69 BSR_8 = 0,
70 BSR_16 = 1,
71 BSR_64 = 2,
72 BSR_128 = 3,
73 BSR_4096 = 4,
74 BSR_UNKNOWN = 5,
75 BSR_MAX = 6,
76};
77
78static unsigned bsr_types[BSR_MAX];
79
80static ssize_t
81bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf)
82{
83 struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
84 return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
85}
86static DEVICE_ATTR_RO(bsr_size);
87
88static ssize_t
89bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf)
90{
91 struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
92 return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
93}
94static DEVICE_ATTR_RO(bsr_stride);
95
96static ssize_t
97bsr_length_show(struct device *dev, struct device_attribute *attr, char *buf)
98{
99 struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
100 return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
101}
102static DEVICE_ATTR_RO(bsr_length);
103
104static struct attribute *bsr_dev_attrs[] = {
105 &dev_attr_bsr_size.attr,
106 &dev_attr_bsr_stride.attr,
107 &dev_attr_bsr_length.attr,
108 NULL,
109};
110ATTRIBUTE_GROUPS(bsr_dev);
111
112static int bsr_mmap(struct file *filp, struct vm_area_struct *vma)
113{
114 unsigned long size = vma->vm_end - vma->vm_start;
115 struct bsr_dev *dev = filp->private_data;
116 int ret;
117
118 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
119
120 /* check for the case of a small BSR device and map one 4k page for it*/
121 if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE)
122 ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12,
123 vma->vm_page_prot);
124 else if (size <= dev->bsr_len)
125 ret = io_remap_pfn_range(vma, vma->vm_start,
126 dev->bsr_addr >> PAGE_SHIFT,
127 size, vma->vm_page_prot);
128 else
129 return -EINVAL;
130
131 if (ret)
132 return -EAGAIN;
133
134 return 0;
135}
136
137static int bsr_open(struct inode *inode, struct file *filp)
138{
139 struct cdev *cdev = inode->i_cdev;
140 struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);
141
142 filp->private_data = dev;
143 return 0;
144}
145
146static const struct file_operations bsr_fops = {
147 .owner = THIS_MODULE,
148 .mmap = bsr_mmap,
149 .open = bsr_open,
150 .llseek = noop_llseek,
151};
152
153static void bsr_cleanup_devs(void)
154{
155 struct bsr_dev *cur, *n;
156
157 list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
158 if (cur->bsr_device) {
159 cdev_del(&cur->bsr_cdev);
160 device_del(cur->bsr_device);
161 }
162 list_del(&cur->bsr_list);
163 kfree(cur);
164 }
165}
166
167static int bsr_add_node(struct device_node *bn)
168{
169 int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
170 const u32 *bsr_stride;
171 const u32 *bsr_bytes;
172 unsigned i;
173 int ret = -ENODEV;
174
175 bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
176 bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
177
178 if (!bsr_stride || !bsr_bytes ||
179 (bsr_stride_len != bsr_bytes_len)) {
180 printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
181 return ret;
182 }
183
184 num_bsr_devs = bsr_bytes_len / sizeof(u32);
185
186 for (i = 0 ; i < num_bsr_devs; i++) {
187 struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
188 GFP_KERNEL);
189 struct resource res;
190 int result;
191
192 if (!cur) {
193 printk(KERN_ERR "Unable to alloc bsr dev\n");
194 ret = -ENOMEM;
195 goto out_err;
196 }
197
198 result = of_address_to_resource(bn, i, &res);
199 if (result < 0) {
200 printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
201 kfree(cur);
202 continue;
203 }
204
205 cur->bsr_minor = i + total_bsr_devs;
206 cur->bsr_addr = res.start;
207 cur->bsr_len = resource_size(&res);
208 cur->bsr_bytes = bsr_bytes[i];
209 cur->bsr_stride = bsr_stride[i];
210 cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
211
212 /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
213 /* we can only map 4k of it, so only advertise the 4k in sysfs */
214 if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
215 cur->bsr_len = 4096;
216
217 switch(cur->bsr_bytes) {
218 case 8:
219 cur->bsr_type = BSR_8;
220 break;
221 case 16:
222 cur->bsr_type = BSR_16;
223 break;
224 case 64:
225 cur->bsr_type = BSR_64;
226 break;
227 case 128:
228 cur->bsr_type = BSR_128;
229 break;
230 case 4096:
231 cur->bsr_type = BSR_4096;
232 break;
233 default:
234 cur->bsr_type = BSR_UNKNOWN;
235 }
236
237 cur->bsr_num = bsr_types[cur->bsr_type];
238 snprintf(cur->bsr_name, 32, "bsr%d_%d",
239 cur->bsr_bytes, cur->bsr_num);
240
241 cdev_init(&cur->bsr_cdev, &bsr_fops);
242 result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
243 if (result) {
244 kfree(cur);
245 goto out_err;
246 }
247
248 cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
249 cur, "%s", cur->bsr_name);
250 if (IS_ERR(cur->bsr_device)) {
251 printk(KERN_ERR "device_create failed for %s\n",
252 cur->bsr_name);
253 cdev_del(&cur->bsr_cdev);
254 kfree(cur);
255 goto out_err;
256 }
257
258 bsr_types[cur->bsr_type] = cur->bsr_num + 1;
259 list_add_tail(&cur->bsr_list, &bsr_devs);
260 }
261
262 total_bsr_devs += num_bsr_devs;
263
264 return 0;
265
266 out_err:
267
268 bsr_cleanup_devs();
269 return ret;
270}
271
272static int bsr_create_devs(struct device_node *bn)
273{
274 int ret;
275
276 while (bn) {
277 ret = bsr_add_node(bn);
278 if (ret) {
279 of_node_put(bn);
280 return ret;
281 }
282 bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
283 }
284 return 0;
285}
286
287static int __init bsr_init(void)
288{
289 struct device_node *np;
290 dev_t bsr_dev;
291 int ret = -ENODEV;
292
293 np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
294 if (!np)
295 goto out_err;
296
297 bsr_class = class_create(THIS_MODULE, "bsr");
298 if (IS_ERR(bsr_class)) {
299 printk(KERN_ERR "class_create() failed for bsr_class\n");
300 ret = PTR_ERR(bsr_class);
301 goto out_err_1;
302 }
303 bsr_class->dev_groups = bsr_dev_groups;
304
305 ret = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
306 bsr_major = MAJOR(bsr_dev);
307 if (ret < 0) {
308 printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
309 goto out_err_2;
310 }
311
312 ret = bsr_create_devs(np);
313 if (ret < 0) {
314 np = NULL;
315 goto out_err_3;
316 }
317
318 return 0;
319
320 out_err_3:
321 unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
322
323 out_err_2:
324 class_destroy(bsr_class);
325
326 out_err_1:
327 of_node_put(np);
328
329 out_err:
330
331 return ret;
332}
333
334static void __exit bsr_exit(void)
335{
336
337 bsr_cleanup_devs();
338
339 if (bsr_class)
340 class_destroy(bsr_class);
341
342 if (bsr_major)
343 unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
344}
345
346module_init(bsr_init);
347module_exit(bsr_exit);
348MODULE_LICENSE("GPL");
349MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");