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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> | |
5a0e3ad6 | 30 | #include <linux/slab.h> |
04a85d12 | 31 | #include <asm/pgtable.h> |
fe9e8d53 SR |
32 | #include <asm/io.h> |
33 | ||
34 | /* | |
35 | This driver exposes a special register which can be used for fast | |
36 | synchronization across a large SMP machine. The hardware is exposed | |
37 | as an array of bytes where each process will write to one of the bytes to | |
38 | indicate it has finished the current stage and this update is broadcast to | |
39 | all processors without having to bounce a cacheline between them. In | |
40 | POWER5 and POWER6 there is one of these registers per SMP, but it is | |
41 | presented in two forms; first, it is given as a whole and then as a number | |
42 | of smaller registers which alias to parts of the single whole register. | |
43 | This can potentially allow multiple groups of processes to each have their | |
44 | own private synchronization device. | |
45 | ||
46 | Note that this hardware *must* be written to using *only* single byte writes. | |
47 | It may be read using 1, 2, 4, or 8 byte loads which must be aligned since | |
48 | this region is treated as cache-inhibited processes should also use a | |
49 | full sync before and after writing to the BSR to ensure all stores and | |
50 | the BSR update have made it to all chips in the system | |
51 | */ | |
52 | ||
53 | /* This is arbitrary number, up to Power6 it's been 17 or fewer */ | |
54 | #define BSR_MAX_DEVS (32) | |
55 | ||
56 | struct bsr_dev { | |
57 | u64 bsr_addr; /* Real address */ | |
58 | u64 bsr_len; /* length of mem region we can map */ | |
59 | unsigned bsr_bytes; /* size of the BSR reg itself */ | |
60 | unsigned bsr_stride; /* interval at which BSR repeats in the page */ | |
61 | unsigned bsr_type; /* maps to enum below */ | |
62 | unsigned bsr_num; /* bsr id number for its type */ | |
63 | int bsr_minor; | |
64 | ||
a0e2f9f4 SR |
65 | struct list_head bsr_list; |
66 | ||
fe9e8d53 SR |
67 | dev_t bsr_dev; |
68 | struct cdev bsr_cdev; | |
69 | struct device *bsr_device; | |
70 | char bsr_name[32]; | |
71 | ||
72 | }; | |
73 | ||
a0e2f9f4 SR |
74 | static unsigned total_bsr_devs; |
75 | static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); | |
fe9e8d53 SR |
76 | static struct class *bsr_class; |
77 | static int bsr_major; | |
78 | ||
79 | enum { | |
e4031d52 SR |
80 | BSR_8 = 0, |
81 | BSR_16 = 1, | |
82 | BSR_64 = 2, | |
83 | BSR_128 = 3, | |
84 | BSR_4096 = 4, | |
85 | BSR_UNKNOWN = 5, | |
86 | BSR_MAX = 6, | |
fe9e8d53 SR |
87 | }; |
88 | ||
89 | static unsigned bsr_types[BSR_MAX]; | |
90 | ||
91 | static ssize_t | |
92 | bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf) | |
93 | { | |
94 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
95 | return sprintf(buf, "%u\n", bsr_dev->bsr_bytes); | |
96 | } | |
97 | ||
98 | static ssize_t | |
99 | bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf) | |
100 | { | |
101 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
102 | return sprintf(buf, "%u\n", bsr_dev->bsr_stride); | |
103 | } | |
104 | ||
105 | static ssize_t | |
106 | bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf) | |
107 | { | |
108 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
1901515c | 109 | return sprintf(buf, "%llu\n", bsr_dev->bsr_len); |
fe9e8d53 SR |
110 | } |
111 | ||
112 | static struct device_attribute bsr_dev_attrs[] = { | |
113 | __ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL), | |
114 | __ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL), | |
115 | __ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL), | |
116 | __ATTR_NULL | |
117 | }; | |
118 | ||
119 | static int bsr_mmap(struct file *filp, struct vm_area_struct *vma) | |
120 | { | |
121 | unsigned long size = vma->vm_end - vma->vm_start; | |
122 | struct bsr_dev *dev = filp->private_data; | |
04a85d12 | 123 | int ret; |
fe9e8d53 | 124 | |
fe9e8d53 SR |
125 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
126 | ||
04a85d12 SR |
127 | /* check for the case of a small BSR device and map one 4k page for it*/ |
128 | if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE) | |
129 | ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12, | |
130 | vma->vm_page_prot); | |
131 | else if (size <= dev->bsr_len) | |
132 | ret = io_remap_pfn_range(vma, vma->vm_start, | |
133 | dev->bsr_addr >> PAGE_SHIFT, | |
134 | size, vma->vm_page_prot); | |
135 | else | |
136 | return -EINVAL; | |
137 | ||
138 | if (ret) | |
fe9e8d53 SR |
139 | return -EAGAIN; |
140 | ||
141 | return 0; | |
142 | } | |
143 | ||
144 | static int bsr_open(struct inode * inode, struct file * filp) | |
145 | { | |
146 | struct cdev *cdev = inode->i_cdev; | |
147 | struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev); | |
148 | ||
149 | filp->private_data = dev; | |
150 | return 0; | |
151 | } | |
152 | ||
27157a70 | 153 | static const struct file_operations bsr_fops = { |
fe9e8d53 SR |
154 | .owner = THIS_MODULE, |
155 | .mmap = bsr_mmap, | |
156 | .open = bsr_open, | |
157 | }; | |
158 | ||
159 | static void bsr_cleanup_devs(void) | |
160 | { | |
a0e2f9f4 SR |
161 | struct bsr_dev *cur, *n; |
162 | ||
163 | list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { | |
fe9e8d53 SR |
164 | if (cur->bsr_device) { |
165 | cdev_del(&cur->bsr_cdev); | |
166 | device_del(cur->bsr_device); | |
167 | } | |
a0e2f9f4 SR |
168 | list_del(&cur->bsr_list); |
169 | kfree(cur); | |
fe9e8d53 | 170 | } |
fe9e8d53 SR |
171 | } |
172 | ||
a0e2f9f4 | 173 | static int bsr_add_node(struct device_node *bn) |
fe9e8d53 | 174 | { |
a0e2f9f4 | 175 | int bsr_stride_len, bsr_bytes_len, num_bsr_devs; |
fe9e8d53 SR |
176 | const u32 *bsr_stride; |
177 | const u32 *bsr_bytes; | |
178 | unsigned i; | |
a0e2f9f4 | 179 | int ret = -ENODEV; |
fe9e8d53 SR |
180 | |
181 | bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len); | |
182 | bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len); | |
183 | ||
184 | if (!bsr_stride || !bsr_bytes || | |
185 | (bsr_stride_len != bsr_bytes_len)) { | |
186 | printk(KERN_ERR "bsr of-node has missing/incorrect property\n"); | |
a0e2f9f4 | 187 | return ret; |
fe9e8d53 SR |
188 | } |
189 | ||
190 | num_bsr_devs = bsr_bytes_len / sizeof(u32); | |
191 | ||
fe9e8d53 | 192 | for (i = 0 ; i < num_bsr_devs; i++) { |
a0e2f9f4 SR |
193 | struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), |
194 | GFP_KERNEL); | |
fe9e8d53 SR |
195 | struct resource res; |
196 | int result; | |
197 | ||
a0e2f9f4 SR |
198 | if (!cur) { |
199 | printk(KERN_ERR "Unable to alloc bsr dev\n"); | |
200 | ret = -ENOMEM; | |
201 | goto out_err; | |
202 | } | |
203 | ||
fe9e8d53 SR |
204 | result = of_address_to_resource(bn, i, &res); |
205 | if (result < 0) { | |
a0e2f9f4 SR |
206 | printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); |
207 | kfree(cur); | |
208 | continue; | |
fe9e8d53 SR |
209 | } |
210 | ||
a0e2f9f4 | 211 | cur->bsr_minor = i + total_bsr_devs; |
fe9e8d53 SR |
212 | cur->bsr_addr = res.start; |
213 | cur->bsr_len = res.end - res.start + 1; | |
214 | cur->bsr_bytes = bsr_bytes[i]; | |
215 | cur->bsr_stride = bsr_stride[i]; | |
a0e2f9f4 | 216 | cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); |
fe9e8d53 | 217 | |
04a85d12 SR |
218 | /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */ |
219 | /* we can only map 4k of it, so only advertise the 4k in sysfs */ | |
220 | if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE) | |
221 | cur->bsr_len = 4096; | |
222 | ||
fe9e8d53 SR |
223 | switch(cur->bsr_bytes) { |
224 | case 8: | |
225 | cur->bsr_type = BSR_8; | |
226 | break; | |
227 | case 16: | |
228 | cur->bsr_type = BSR_16; | |
229 | break; | |
230 | case 64: | |
231 | cur->bsr_type = BSR_64; | |
232 | break; | |
233 | case 128: | |
234 | cur->bsr_type = BSR_128; | |
235 | break; | |
e4031d52 SR |
236 | case 4096: |
237 | cur->bsr_type = BSR_4096; | |
238 | break; | |
fe9e8d53 SR |
239 | default: |
240 | cur->bsr_type = BSR_UNKNOWN; | |
fe9e8d53 SR |
241 | } |
242 | ||
243 | cur->bsr_num = bsr_types[cur->bsr_type]; | |
fe9e8d53 SR |
244 | snprintf(cur->bsr_name, 32, "bsr%d_%d", |
245 | cur->bsr_bytes, cur->bsr_num); | |
246 | ||
247 | cdev_init(&cur->bsr_cdev, &bsr_fops); | |
248 | result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1); | |
a0e2f9f4 SR |
249 | if (result) { |
250 | kfree(cur); | |
fe9e8d53 | 251 | goto out_err; |
a0e2f9f4 | 252 | } |
fe9e8d53 | 253 | |
03457cd4 GKH |
254 | cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, |
255 | cur, cur->bsr_name); | |
30c96ce5 | 256 | if (IS_ERR(cur->bsr_device)) { |
fe9e8d53 SR |
257 | printk(KERN_ERR "device_create failed for %s\n", |
258 | cur->bsr_name); | |
259 | cdev_del(&cur->bsr_cdev); | |
a0e2f9f4 | 260 | kfree(cur); |
fe9e8d53 SR |
261 | goto out_err; |
262 | } | |
a0e2f9f4 SR |
263 | |
264 | bsr_types[cur->bsr_type] = cur->bsr_num + 1; | |
265 | list_add_tail(&cur->bsr_list, &bsr_devs); | |
fe9e8d53 SR |
266 | } |
267 | ||
a0e2f9f4 SR |
268 | total_bsr_devs += num_bsr_devs; |
269 | ||
fe9e8d53 SR |
270 | return 0; |
271 | ||
272 | out_err: | |
273 | ||
274 | bsr_cleanup_devs(); | |
a0e2f9f4 SR |
275 | return ret; |
276 | } | |
277 | ||
278 | static int bsr_create_devs(struct device_node *bn) | |
279 | { | |
280 | int ret; | |
281 | ||
282 | while (bn) { | |
283 | ret = bsr_add_node(bn); | |
284 | if (ret) { | |
285 | of_node_put(bn); | |
286 | return ret; | |
287 | } | |
288 | bn = of_find_compatible_node(bn, NULL, "ibm,bsr"); | |
289 | } | |
290 | return 0; | |
fe9e8d53 SR |
291 | } |
292 | ||
293 | static int __init bsr_init(void) | |
294 | { | |
295 | struct device_node *np; | |
296 | dev_t bsr_dev = MKDEV(bsr_major, 0); | |
297 | int ret = -ENODEV; | |
298 | int result; | |
299 | ||
a0e2f9f4 | 300 | np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); |
fe9e8d53 SR |
301 | if (!np) |
302 | goto out_err; | |
303 | ||
304 | bsr_class = class_create(THIS_MODULE, "bsr"); | |
305 | if (IS_ERR(bsr_class)) { | |
306 | printk(KERN_ERR "class_create() failed for bsr_class\n"); | |
307 | goto out_err_1; | |
308 | } | |
309 | bsr_class->dev_attrs = bsr_dev_attrs; | |
310 | ||
311 | result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr"); | |
312 | bsr_major = MAJOR(bsr_dev); | |
313 | if (result < 0) { | |
314 | printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n"); | |
315 | goto out_err_2; | |
316 | } | |
317 | ||
a0e2f9f4 SR |
318 | if ((ret = bsr_create_devs(np)) < 0) { |
319 | np = NULL; | |
fe9e8d53 | 320 | goto out_err_3; |
a0e2f9f4 | 321 | } |
fe9e8d53 SR |
322 | |
323 | return 0; | |
324 | ||
325 | out_err_3: | |
326 | unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS); | |
327 | ||
328 | out_err_2: | |
329 | class_destroy(bsr_class); | |
330 | ||
331 | out_err_1: | |
332 | of_node_put(np); | |
333 | ||
334 | out_err: | |
335 | ||
336 | return ret; | |
337 | } | |
338 | ||
339 | static void __exit bsr_exit(void) | |
340 | { | |
341 | ||
342 | bsr_cleanup_devs(); | |
343 | ||
344 | if (bsr_class) | |
345 | class_destroy(bsr_class); | |
346 | ||
347 | if (bsr_major) | |
348 | unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS); | |
349 | } | |
350 | ||
351 | module_init(bsr_init); | |
352 | module_exit(bsr_exit); | |
353 | MODULE_LICENSE("GPL"); | |
354 | MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); |