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fe9e8d53 SR |
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/module.h> | |
27 | #include <linux/cdev.h> | |
28 | #include <linux/list.h> | |
29 | #include <linux/mm.h> | |
04a85d12 | 30 | #include <asm/pgtable.h> |
fe9e8d53 SR |
31 | #include <asm/io.h> |
32 | ||
33 | /* | |
34 | This driver exposes a special register which can be used for fast | |
35 | synchronization across a large SMP machine. The hardware is exposed | |
36 | as an array of bytes where each process will write to one of the bytes to | |
37 | indicate it has finished the current stage and this update is broadcast to | |
38 | all processors without having to bounce a cacheline between them. In | |
39 | POWER5 and POWER6 there is one of these registers per SMP, but it is | |
40 | presented in two forms; first, it is given as a whole and then as a number | |
41 | of smaller registers which alias to parts of the single whole register. | |
42 | This can potentially allow multiple groups of processes to each have their | |
43 | own private synchronization device. | |
44 | ||
45 | Note that this hardware *must* be written to using *only* single byte writes. | |
46 | It may be read using 1, 2, 4, or 8 byte loads which must be aligned since | |
47 | this region is treated as cache-inhibited processes should also use a | |
48 | full sync before and after writing to the BSR to ensure all stores and | |
49 | the BSR update have made it to all chips in the system | |
50 | */ | |
51 | ||
52 | /* This is arbitrary number, up to Power6 it's been 17 or fewer */ | |
53 | #define BSR_MAX_DEVS (32) | |
54 | ||
55 | struct bsr_dev { | |
56 | u64 bsr_addr; /* Real address */ | |
57 | u64 bsr_len; /* length of mem region we can map */ | |
58 | unsigned bsr_bytes; /* size of the BSR reg itself */ | |
59 | unsigned bsr_stride; /* interval at which BSR repeats in the page */ | |
60 | unsigned bsr_type; /* maps to enum below */ | |
61 | unsigned bsr_num; /* bsr id number for its type */ | |
62 | int bsr_minor; | |
63 | ||
a0e2f9f4 SR |
64 | struct list_head bsr_list; |
65 | ||
fe9e8d53 SR |
66 | dev_t bsr_dev; |
67 | struct cdev bsr_cdev; | |
68 | struct device *bsr_device; | |
69 | char bsr_name[32]; | |
70 | ||
71 | }; | |
72 | ||
a0e2f9f4 SR |
73 | static unsigned total_bsr_devs; |
74 | static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); | |
fe9e8d53 SR |
75 | static struct class *bsr_class; |
76 | static int bsr_major; | |
77 | ||
78 | enum { | |
e4031d52 SR |
79 | BSR_8 = 0, |
80 | BSR_16 = 1, | |
81 | BSR_64 = 2, | |
82 | BSR_128 = 3, | |
83 | BSR_4096 = 4, | |
84 | BSR_UNKNOWN = 5, | |
85 | BSR_MAX = 6, | |
fe9e8d53 SR |
86 | }; |
87 | ||
88 | static unsigned bsr_types[BSR_MAX]; | |
89 | ||
90 | static ssize_t | |
91 | bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf) | |
92 | { | |
93 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
94 | return sprintf(buf, "%u\n", bsr_dev->bsr_bytes); | |
95 | } | |
96 | ||
97 | static ssize_t | |
98 | bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf) | |
99 | { | |
100 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
101 | return sprintf(buf, "%u\n", bsr_dev->bsr_stride); | |
102 | } | |
103 | ||
104 | static ssize_t | |
105 | bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf) | |
106 | { | |
107 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
1901515c | 108 | return sprintf(buf, "%llu\n", bsr_dev->bsr_len); |
fe9e8d53 SR |
109 | } |
110 | ||
111 | static struct device_attribute bsr_dev_attrs[] = { | |
112 | __ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL), | |
113 | __ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL), | |
114 | __ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL), | |
115 | __ATTR_NULL | |
116 | }; | |
117 | ||
118 | static int bsr_mmap(struct file *filp, struct vm_area_struct *vma) | |
119 | { | |
120 | unsigned long size = vma->vm_end - vma->vm_start; | |
121 | struct bsr_dev *dev = filp->private_data; | |
04a85d12 | 122 | int ret; |
fe9e8d53 | 123 | |
fe9e8d53 SR |
124 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
125 | ||
04a85d12 SR |
126 | /* check for the case of a small BSR device and map one 4k page for it*/ |
127 | if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE) | |
128 | ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12, | |
129 | vma->vm_page_prot); | |
130 | else if (size <= dev->bsr_len) | |
131 | ret = io_remap_pfn_range(vma, vma->vm_start, | |
132 | dev->bsr_addr >> PAGE_SHIFT, | |
133 | size, vma->vm_page_prot); | |
134 | else | |
135 | return -EINVAL; | |
136 | ||
137 | if (ret) | |
fe9e8d53 SR |
138 | return -EAGAIN; |
139 | ||
140 | return 0; | |
141 | } | |
142 | ||
143 | static int bsr_open(struct inode * inode, struct file * filp) | |
144 | { | |
145 | struct cdev *cdev = inode->i_cdev; | |
146 | struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev); | |
147 | ||
148 | filp->private_data = dev; | |
149 | return 0; | |
150 | } | |
151 | ||
27157a70 | 152 | static const struct file_operations bsr_fops = { |
fe9e8d53 SR |
153 | .owner = THIS_MODULE, |
154 | .mmap = bsr_mmap, | |
155 | .open = bsr_open, | |
156 | }; | |
157 | ||
158 | static void bsr_cleanup_devs(void) | |
159 | { | |
a0e2f9f4 SR |
160 | struct bsr_dev *cur, *n; |
161 | ||
162 | list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { | |
fe9e8d53 SR |
163 | if (cur->bsr_device) { |
164 | cdev_del(&cur->bsr_cdev); | |
165 | device_del(cur->bsr_device); | |
166 | } | |
a0e2f9f4 SR |
167 | list_del(&cur->bsr_list); |
168 | kfree(cur); | |
fe9e8d53 | 169 | } |
fe9e8d53 SR |
170 | } |
171 | ||
a0e2f9f4 | 172 | static int bsr_add_node(struct device_node *bn) |
fe9e8d53 | 173 | { |
a0e2f9f4 | 174 | int bsr_stride_len, bsr_bytes_len, num_bsr_devs; |
fe9e8d53 SR |
175 | const u32 *bsr_stride; |
176 | const u32 *bsr_bytes; | |
177 | unsigned i; | |
a0e2f9f4 | 178 | int ret = -ENODEV; |
fe9e8d53 SR |
179 | |
180 | bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len); | |
181 | bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len); | |
182 | ||
183 | if (!bsr_stride || !bsr_bytes || | |
184 | (bsr_stride_len != bsr_bytes_len)) { | |
185 | printk(KERN_ERR "bsr of-node has missing/incorrect property\n"); | |
a0e2f9f4 | 186 | return ret; |
fe9e8d53 SR |
187 | } |
188 | ||
189 | num_bsr_devs = bsr_bytes_len / sizeof(u32); | |
190 | ||
fe9e8d53 | 191 | for (i = 0 ; i < num_bsr_devs; i++) { |
a0e2f9f4 SR |
192 | struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), |
193 | GFP_KERNEL); | |
fe9e8d53 SR |
194 | struct resource res; |
195 | int result; | |
196 | ||
a0e2f9f4 SR |
197 | if (!cur) { |
198 | printk(KERN_ERR "Unable to alloc bsr dev\n"); | |
199 | ret = -ENOMEM; | |
200 | goto out_err; | |
201 | } | |
202 | ||
fe9e8d53 SR |
203 | result = of_address_to_resource(bn, i, &res); |
204 | if (result < 0) { | |
a0e2f9f4 SR |
205 | printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); |
206 | kfree(cur); | |
207 | continue; | |
fe9e8d53 SR |
208 | } |
209 | ||
a0e2f9f4 | 210 | cur->bsr_minor = i + total_bsr_devs; |
fe9e8d53 SR |
211 | cur->bsr_addr = res.start; |
212 | cur->bsr_len = res.end - res.start + 1; | |
213 | cur->bsr_bytes = bsr_bytes[i]; | |
214 | cur->bsr_stride = bsr_stride[i]; | |
a0e2f9f4 | 215 | cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); |
fe9e8d53 | 216 | |
04a85d12 SR |
217 | /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */ |
218 | /* we can only map 4k of it, so only advertise the 4k in sysfs */ | |
219 | if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE) | |
220 | cur->bsr_len = 4096; | |
221 | ||
fe9e8d53 SR |
222 | switch(cur->bsr_bytes) { |
223 | case 8: | |
224 | cur->bsr_type = BSR_8; | |
225 | break; | |
226 | case 16: | |
227 | cur->bsr_type = BSR_16; | |
228 | break; | |
229 | case 64: | |
230 | cur->bsr_type = BSR_64; | |
231 | break; | |
232 | case 128: | |
233 | cur->bsr_type = BSR_128; | |
234 | break; | |
e4031d52 SR |
235 | case 4096: |
236 | cur->bsr_type = BSR_4096; | |
237 | break; | |
fe9e8d53 SR |
238 | default: |
239 | cur->bsr_type = BSR_UNKNOWN; | |
fe9e8d53 SR |
240 | } |
241 | ||
242 | cur->bsr_num = bsr_types[cur->bsr_type]; | |
fe9e8d53 SR |
243 | snprintf(cur->bsr_name, 32, "bsr%d_%d", |
244 | cur->bsr_bytes, cur->bsr_num); | |
245 | ||
246 | cdev_init(&cur->bsr_cdev, &bsr_fops); | |
247 | result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1); | |
a0e2f9f4 SR |
248 | if (result) { |
249 | kfree(cur); | |
fe9e8d53 | 250 | goto out_err; |
a0e2f9f4 | 251 | } |
fe9e8d53 | 252 | |
03457cd4 GKH |
253 | cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, |
254 | cur, cur->bsr_name); | |
fe9e8d53 SR |
255 | if (!cur->bsr_device) { |
256 | printk(KERN_ERR "device_create failed for %s\n", | |
257 | cur->bsr_name); | |
258 | cdev_del(&cur->bsr_cdev); | |
a0e2f9f4 | 259 | kfree(cur); |
fe9e8d53 SR |
260 | goto out_err; |
261 | } | |
a0e2f9f4 SR |
262 | |
263 | bsr_types[cur->bsr_type] = cur->bsr_num + 1; | |
264 | list_add_tail(&cur->bsr_list, &bsr_devs); | |
fe9e8d53 SR |
265 | } |
266 | ||
a0e2f9f4 SR |
267 | total_bsr_devs += num_bsr_devs; |
268 | ||
fe9e8d53 SR |
269 | return 0; |
270 | ||
271 | out_err: | |
272 | ||
273 | bsr_cleanup_devs(); | |
a0e2f9f4 SR |
274 | return ret; |
275 | } | |
276 | ||
277 | static int bsr_create_devs(struct device_node *bn) | |
278 | { | |
279 | int ret; | |
280 | ||
281 | while (bn) { | |
282 | ret = bsr_add_node(bn); | |
283 | if (ret) { | |
284 | of_node_put(bn); | |
285 | return ret; | |
286 | } | |
287 | bn = of_find_compatible_node(bn, NULL, "ibm,bsr"); | |
288 | } | |
289 | return 0; | |
fe9e8d53 SR |
290 | } |
291 | ||
292 | static int __init bsr_init(void) | |
293 | { | |
294 | struct device_node *np; | |
295 | dev_t bsr_dev = MKDEV(bsr_major, 0); | |
296 | int ret = -ENODEV; | |
297 | int result; | |
298 | ||
a0e2f9f4 | 299 | np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); |
fe9e8d53 SR |
300 | if (!np) |
301 | goto out_err; | |
302 | ||
303 | bsr_class = class_create(THIS_MODULE, "bsr"); | |
304 | if (IS_ERR(bsr_class)) { | |
305 | printk(KERN_ERR "class_create() failed for bsr_class\n"); | |
306 | goto out_err_1; | |
307 | } | |
308 | bsr_class->dev_attrs = bsr_dev_attrs; | |
309 | ||
310 | result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr"); | |
311 | bsr_major = MAJOR(bsr_dev); | |
312 | if (result < 0) { | |
313 | printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n"); | |
314 | goto out_err_2; | |
315 | } | |
316 | ||
a0e2f9f4 SR |
317 | if ((ret = bsr_create_devs(np)) < 0) { |
318 | np = NULL; | |
fe9e8d53 | 319 | goto out_err_3; |
a0e2f9f4 | 320 | } |
fe9e8d53 SR |
321 | |
322 | return 0; | |
323 | ||
324 | out_err_3: | |
325 | unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS); | |
326 | ||
327 | out_err_2: | |
328 | class_destroy(bsr_class); | |
329 | ||
330 | out_err_1: | |
331 | of_node_put(np); | |
332 | ||
333 | out_err: | |
334 | ||
335 | return ret; | |
336 | } | |
337 | ||
338 | static void __exit bsr_exit(void) | |
339 | { | |
340 | ||
341 | bsr_cleanup_devs(); | |
342 | ||
343 | if (bsr_class) | |
344 | class_destroy(bsr_class); | |
345 | ||
346 | if (bsr_major) | |
347 | unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS); | |
348 | } | |
349 | ||
350 | module_init(bsr_init); | |
351 | module_exit(bsr_exit); | |
352 | MODULE_LICENSE("GPL"); | |
353 | MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); |