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