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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> | |
22ae782f | 26 | #include <linux/fs.h> |
fe9e8d53 SR |
27 | #include <linux/module.h> |
28 | #include <linux/cdev.h> | |
29 | #include <linux/list.h> | |
30 | #include <linux/mm.h> | |
5a0e3ad6 | 31 | #include <linux/slab.h> |
04a85d12 | 32 | #include <asm/pgtable.h> |
fe9e8d53 SR |
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 | ||
57 | struct 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 | ||
a0e2f9f4 SR |
66 | struct list_head bsr_list; |
67 | ||
fe9e8d53 SR |
68 | dev_t bsr_dev; |
69 | struct cdev bsr_cdev; | |
70 | struct device *bsr_device; | |
71 | char bsr_name[32]; | |
72 | ||
73 | }; | |
74 | ||
a0e2f9f4 SR |
75 | static unsigned total_bsr_devs; |
76 | static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); | |
fe9e8d53 SR |
77 | static struct class *bsr_class; |
78 | static int bsr_major; | |
79 | ||
80 | enum { | |
e4031d52 SR |
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, | |
fe9e8d53 SR |
88 | }; |
89 | ||
90 | static unsigned bsr_types[BSR_MAX]; | |
91 | ||
92 | static ssize_t | |
93 | bsr_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 | ||
99 | static ssize_t | |
100 | bsr_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 | ||
106 | static ssize_t | |
107 | bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf) | |
108 | { | |
109 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
1901515c | 110 | return sprintf(buf, "%llu\n", bsr_dev->bsr_len); |
fe9e8d53 SR |
111 | } |
112 | ||
113 | static 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 | ||
120 | static 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; | |
04a85d12 | 124 | int ret; |
fe9e8d53 | 125 | |
fe9e8d53 SR |
126 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
127 | ||
04a85d12 SR |
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) | |
fe9e8d53 SR |
140 | return -EAGAIN; |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
145 | static 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 | ||
27157a70 | 154 | static const struct file_operations bsr_fops = { |
fe9e8d53 SR |
155 | .owner = THIS_MODULE, |
156 | .mmap = bsr_mmap, | |
157 | .open = bsr_open, | |
158 | }; | |
159 | ||
160 | static void bsr_cleanup_devs(void) | |
161 | { | |
a0e2f9f4 SR |
162 | struct bsr_dev *cur, *n; |
163 | ||
164 | list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { | |
fe9e8d53 SR |
165 | if (cur->bsr_device) { |
166 | cdev_del(&cur->bsr_cdev); | |
167 | device_del(cur->bsr_device); | |
168 | } | |
a0e2f9f4 SR |
169 | list_del(&cur->bsr_list); |
170 | kfree(cur); | |
fe9e8d53 | 171 | } |
fe9e8d53 SR |
172 | } |
173 | ||
a0e2f9f4 | 174 | static int bsr_add_node(struct device_node *bn) |
fe9e8d53 | 175 | { |
a0e2f9f4 | 176 | int bsr_stride_len, bsr_bytes_len, num_bsr_devs; |
fe9e8d53 SR |
177 | const u32 *bsr_stride; |
178 | const u32 *bsr_bytes; | |
179 | unsigned i; | |
a0e2f9f4 | 180 | int ret = -ENODEV; |
fe9e8d53 SR |
181 | |
182 | bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len); | |
183 | bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len); | |
184 | ||
185 | if (!bsr_stride || !bsr_bytes || | |
186 | (bsr_stride_len != bsr_bytes_len)) { | |
187 | printk(KERN_ERR "bsr of-node has missing/incorrect property\n"); | |
a0e2f9f4 | 188 | return ret; |
fe9e8d53 SR |
189 | } |
190 | ||
191 | num_bsr_devs = bsr_bytes_len / sizeof(u32); | |
192 | ||
fe9e8d53 | 193 | for (i = 0 ; i < num_bsr_devs; i++) { |
a0e2f9f4 SR |
194 | struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), |
195 | GFP_KERNEL); | |
fe9e8d53 SR |
196 | struct resource res; |
197 | int result; | |
198 | ||
a0e2f9f4 SR |
199 | if (!cur) { |
200 | printk(KERN_ERR "Unable to alloc bsr dev\n"); | |
201 | ret = -ENOMEM; | |
202 | goto out_err; | |
203 | } | |
204 | ||
fe9e8d53 SR |
205 | result = of_address_to_resource(bn, i, &res); |
206 | if (result < 0) { | |
a0e2f9f4 SR |
207 | printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); |
208 | kfree(cur); | |
209 | continue; | |
fe9e8d53 SR |
210 | } |
211 | ||
a0e2f9f4 | 212 | cur->bsr_minor = i + total_bsr_devs; |
fe9e8d53 SR |
213 | cur->bsr_addr = res.start; |
214 | cur->bsr_len = res.end - res.start + 1; | |
215 | cur->bsr_bytes = bsr_bytes[i]; | |
216 | cur->bsr_stride = bsr_stride[i]; | |
a0e2f9f4 | 217 | cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); |
fe9e8d53 | 218 | |
04a85d12 SR |
219 | /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */ |
220 | /* we can only map 4k of it, so only advertise the 4k in sysfs */ | |
221 | if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE) | |
222 | cur->bsr_len = 4096; | |
223 | ||
fe9e8d53 SR |
224 | switch(cur->bsr_bytes) { |
225 | case 8: | |
226 | cur->bsr_type = BSR_8; | |
227 | break; | |
228 | case 16: | |
229 | cur->bsr_type = BSR_16; | |
230 | break; | |
231 | case 64: | |
232 | cur->bsr_type = BSR_64; | |
233 | break; | |
234 | case 128: | |
235 | cur->bsr_type = BSR_128; | |
236 | break; | |
e4031d52 SR |
237 | case 4096: |
238 | cur->bsr_type = BSR_4096; | |
239 | break; | |
fe9e8d53 SR |
240 | default: |
241 | cur->bsr_type = BSR_UNKNOWN; | |
fe9e8d53 SR |
242 | } |
243 | ||
244 | cur->bsr_num = bsr_types[cur->bsr_type]; | |
fe9e8d53 SR |
245 | snprintf(cur->bsr_name, 32, "bsr%d_%d", |
246 | cur->bsr_bytes, cur->bsr_num); | |
247 | ||
248 | cdev_init(&cur->bsr_cdev, &bsr_fops); | |
249 | result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1); | |
a0e2f9f4 SR |
250 | if (result) { |
251 | kfree(cur); | |
fe9e8d53 | 252 | goto out_err; |
a0e2f9f4 | 253 | } |
fe9e8d53 | 254 | |
03457cd4 GKH |
255 | cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, |
256 | cur, cur->bsr_name); | |
30c96ce5 | 257 | if (IS_ERR(cur->bsr_device)) { |
fe9e8d53 SR |
258 | printk(KERN_ERR "device_create failed for %s\n", |
259 | cur->bsr_name); | |
260 | cdev_del(&cur->bsr_cdev); | |
a0e2f9f4 | 261 | kfree(cur); |
fe9e8d53 SR |
262 | goto out_err; |
263 | } | |
a0e2f9f4 SR |
264 | |
265 | bsr_types[cur->bsr_type] = cur->bsr_num + 1; | |
266 | list_add_tail(&cur->bsr_list, &bsr_devs); | |
fe9e8d53 SR |
267 | } |
268 | ||
a0e2f9f4 SR |
269 | total_bsr_devs += num_bsr_devs; |
270 | ||
fe9e8d53 SR |
271 | return 0; |
272 | ||
273 | out_err: | |
274 | ||
275 | bsr_cleanup_devs(); | |
a0e2f9f4 SR |
276 | return ret; |
277 | } | |
278 | ||
279 | static int bsr_create_devs(struct device_node *bn) | |
280 | { | |
281 | int ret; | |
282 | ||
283 | while (bn) { | |
284 | ret = bsr_add_node(bn); | |
285 | if (ret) { | |
286 | of_node_put(bn); | |
287 | return ret; | |
288 | } | |
289 | bn = of_find_compatible_node(bn, NULL, "ibm,bsr"); | |
290 | } | |
291 | return 0; | |
fe9e8d53 SR |
292 | } |
293 | ||
294 | static int __init bsr_init(void) | |
295 | { | |
296 | struct device_node *np; | |
297 | dev_t bsr_dev = MKDEV(bsr_major, 0); | |
298 | int ret = -ENODEV; | |
299 | int result; | |
300 | ||
a0e2f9f4 | 301 | np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); |
fe9e8d53 SR |
302 | if (!np) |
303 | goto out_err; | |
304 | ||
305 | bsr_class = class_create(THIS_MODULE, "bsr"); | |
306 | if (IS_ERR(bsr_class)) { | |
307 | printk(KERN_ERR "class_create() failed for bsr_class\n"); | |
308 | goto out_err_1; | |
309 | } | |
310 | bsr_class->dev_attrs = bsr_dev_attrs; | |
311 | ||
312 | result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr"); | |
313 | bsr_major = MAJOR(bsr_dev); | |
314 | if (result < 0) { | |
315 | printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n"); | |
316 | goto out_err_2; | |
317 | } | |
318 | ||
a0e2f9f4 SR |
319 | if ((ret = bsr_create_devs(np)) < 0) { |
320 | np = NULL; | |
fe9e8d53 | 321 | goto out_err_3; |
a0e2f9f4 | 322 | } |
fe9e8d53 SR |
323 | |
324 | return 0; | |
325 | ||
326 | out_err_3: | |
327 | unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS); | |
328 | ||
329 | out_err_2: | |
330 | class_destroy(bsr_class); | |
331 | ||
332 | out_err_1: | |
333 | of_node_put(np); | |
334 | ||
335 | out_err: | |
336 | ||
337 | return ret; | |
338 | } | |
339 | ||
340 | static void __exit bsr_exit(void) | |
341 | { | |
342 | ||
343 | bsr_cleanup_devs(); | |
344 | ||
345 | if (bsr_class) | |
346 | class_destroy(bsr_class); | |
347 | ||
348 | if (bsr_major) | |
349 | unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS); | |
350 | } | |
351 | ||
352 | module_init(bsr_init); | |
353 | module_exit(bsr_exit); | |
354 | MODULE_LICENSE("GPL"); | |
355 | MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); |