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