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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> | |
5af50730 | 24 | #include <linux/of_address.h> |
fe9e8d53 SR |
25 | #include <linux/of_device.h> |
26 | #include <linux/of_platform.h> | |
22ae782f | 27 | #include <linux/fs.h> |
fe9e8d53 SR |
28 | #include <linux/module.h> |
29 | #include <linux/cdev.h> | |
30 | #include <linux/list.h> | |
31 | #include <linux/mm.h> | |
5a0e3ad6 | 32 | #include <linux/slab.h> |
04a85d12 | 33 | #include <asm/pgtable.h> |
fe9e8d53 SR |
34 | #include <asm/io.h> |
35 | ||
36 | /* | |
37 | This driver exposes a special register which can be used for fast | |
38 | synchronization across a large SMP machine. The hardware is exposed | |
39 | as an array of bytes where each process will write to one of the bytes to | |
40 | indicate it has finished the current stage and this update is broadcast to | |
41 | all processors without having to bounce a cacheline between them. In | |
42 | POWER5 and POWER6 there is one of these registers per SMP, but it is | |
43 | presented in two forms; first, it is given as a whole and then as a number | |
44 | of smaller registers which alias to parts of the single whole register. | |
45 | This can potentially allow multiple groups of processes to each have their | |
46 | own private synchronization device. | |
47 | ||
48 | Note that this hardware *must* be written to using *only* single byte writes. | |
49 | It may be read using 1, 2, 4, or 8 byte loads which must be aligned since | |
50 | this region is treated as cache-inhibited processes should also use a | |
51 | full sync before and after writing to the BSR to ensure all stores and | |
52 | the BSR update have made it to all chips in the system | |
53 | */ | |
54 | ||
55 | /* This is arbitrary number, up to Power6 it's been 17 or fewer */ | |
56 | #define BSR_MAX_DEVS (32) | |
57 | ||
58 | struct bsr_dev { | |
59 | u64 bsr_addr; /* Real address */ | |
60 | u64 bsr_len; /* length of mem region we can map */ | |
61 | unsigned bsr_bytes; /* size of the BSR reg itself */ | |
62 | unsigned bsr_stride; /* interval at which BSR repeats in the page */ | |
63 | unsigned bsr_type; /* maps to enum below */ | |
64 | unsigned bsr_num; /* bsr id number for its type */ | |
65 | int bsr_minor; | |
66 | ||
a0e2f9f4 SR |
67 | struct list_head bsr_list; |
68 | ||
fe9e8d53 SR |
69 | dev_t bsr_dev; |
70 | struct cdev bsr_cdev; | |
71 | struct device *bsr_device; | |
72 | char bsr_name[32]; | |
73 | ||
74 | }; | |
75 | ||
a0e2f9f4 SR |
76 | static unsigned total_bsr_devs; |
77 | static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); | |
fe9e8d53 SR |
78 | static struct class *bsr_class; |
79 | static int bsr_major; | |
80 | ||
81 | enum { | |
e4031d52 SR |
82 | BSR_8 = 0, |
83 | BSR_16 = 1, | |
84 | BSR_64 = 2, | |
85 | BSR_128 = 3, | |
86 | BSR_4096 = 4, | |
87 | BSR_UNKNOWN = 5, | |
88 | BSR_MAX = 6, | |
fe9e8d53 SR |
89 | }; |
90 | ||
91 | static unsigned bsr_types[BSR_MAX]; | |
92 | ||
93 | static ssize_t | |
94 | bsr_size_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, "%u\n", bsr_dev->bsr_bytes); | |
98 | } | |
62e13505 | 99 | static DEVICE_ATTR_RO(bsr_size); |
fe9e8d53 SR |
100 | |
101 | static ssize_t | |
102 | bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf) | |
103 | { | |
104 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
105 | return sprintf(buf, "%u\n", bsr_dev->bsr_stride); | |
106 | } | |
62e13505 | 107 | static DEVICE_ATTR_RO(bsr_stride); |
fe9e8d53 SR |
108 | |
109 | static ssize_t | |
62e13505 | 110 | bsr_length_show(struct device *dev, struct device_attribute *attr, char *buf) |
fe9e8d53 SR |
111 | { |
112 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
1901515c | 113 | return sprintf(buf, "%llu\n", bsr_dev->bsr_len); |
fe9e8d53 | 114 | } |
62e13505 | 115 | static DEVICE_ATTR_RO(bsr_length); |
fe9e8d53 | 116 | |
62e13505 GKH |
117 | static struct attribute *bsr_dev_attrs[] = { |
118 | &dev_attr_bsr_size.attr, | |
119 | &dev_attr_bsr_stride.attr, | |
120 | &dev_attr_bsr_length.attr, | |
121 | NULL, | |
fe9e8d53 | 122 | }; |
62e13505 | 123 | ATTRIBUTE_GROUPS(bsr_dev); |
fe9e8d53 SR |
124 | |
125 | static int bsr_mmap(struct file *filp, struct vm_area_struct *vma) | |
126 | { | |
127 | unsigned long size = vma->vm_end - vma->vm_start; | |
128 | struct bsr_dev *dev = filp->private_data; | |
04a85d12 | 129 | int ret; |
fe9e8d53 | 130 | |
fe9e8d53 SR |
131 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
132 | ||
04a85d12 SR |
133 | /* check for the case of a small BSR device and map one 4k page for it*/ |
134 | if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE) | |
135 | ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12, | |
136 | vma->vm_page_prot); | |
137 | else if (size <= dev->bsr_len) | |
138 | ret = io_remap_pfn_range(vma, vma->vm_start, | |
139 | dev->bsr_addr >> PAGE_SHIFT, | |
140 | size, vma->vm_page_prot); | |
141 | else | |
142 | return -EINVAL; | |
143 | ||
144 | if (ret) | |
fe9e8d53 SR |
145 | return -EAGAIN; |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
150 | static int bsr_open(struct inode * inode, struct file * filp) | |
151 | { | |
152 | struct cdev *cdev = inode->i_cdev; | |
153 | struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev); | |
154 | ||
155 | filp->private_data = dev; | |
156 | return 0; | |
157 | } | |
158 | ||
27157a70 | 159 | static const struct file_operations bsr_fops = { |
fe9e8d53 SR |
160 | .owner = THIS_MODULE, |
161 | .mmap = bsr_mmap, | |
162 | .open = bsr_open, | |
6038f373 | 163 | .llseek = noop_llseek, |
fe9e8d53 SR |
164 | }; |
165 | ||
166 | static void bsr_cleanup_devs(void) | |
167 | { | |
a0e2f9f4 SR |
168 | struct bsr_dev *cur, *n; |
169 | ||
170 | list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { | |
fe9e8d53 SR |
171 | if (cur->bsr_device) { |
172 | cdev_del(&cur->bsr_cdev); | |
173 | device_del(cur->bsr_device); | |
174 | } | |
a0e2f9f4 SR |
175 | list_del(&cur->bsr_list); |
176 | kfree(cur); | |
fe9e8d53 | 177 | } |
fe9e8d53 SR |
178 | } |
179 | ||
a0e2f9f4 | 180 | static int bsr_add_node(struct device_node *bn) |
fe9e8d53 | 181 | { |
a0e2f9f4 | 182 | int bsr_stride_len, bsr_bytes_len, num_bsr_devs; |
fe9e8d53 SR |
183 | const u32 *bsr_stride; |
184 | const u32 *bsr_bytes; | |
185 | unsigned i; | |
a0e2f9f4 | 186 | int ret = -ENODEV; |
fe9e8d53 SR |
187 | |
188 | bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len); | |
189 | bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len); | |
190 | ||
191 | if (!bsr_stride || !bsr_bytes || | |
192 | (bsr_stride_len != bsr_bytes_len)) { | |
193 | printk(KERN_ERR "bsr of-node has missing/incorrect property\n"); | |
a0e2f9f4 | 194 | return ret; |
fe9e8d53 SR |
195 | } |
196 | ||
197 | num_bsr_devs = bsr_bytes_len / sizeof(u32); | |
198 | ||
fe9e8d53 | 199 | for (i = 0 ; i < num_bsr_devs; i++) { |
a0e2f9f4 SR |
200 | struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), |
201 | GFP_KERNEL); | |
fe9e8d53 SR |
202 | struct resource res; |
203 | int result; | |
204 | ||
a0e2f9f4 SR |
205 | if (!cur) { |
206 | printk(KERN_ERR "Unable to alloc bsr dev\n"); | |
207 | ret = -ENOMEM; | |
208 | goto out_err; | |
209 | } | |
210 | ||
fe9e8d53 SR |
211 | result = of_address_to_resource(bn, i, &res); |
212 | if (result < 0) { | |
a0e2f9f4 SR |
213 | printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); |
214 | kfree(cur); | |
215 | continue; | |
fe9e8d53 SR |
216 | } |
217 | ||
a0e2f9f4 | 218 | cur->bsr_minor = i + total_bsr_devs; |
fe9e8d53 | 219 | cur->bsr_addr = res.start; |
28f65c11 | 220 | cur->bsr_len = resource_size(&res); |
fe9e8d53 SR |
221 | cur->bsr_bytes = bsr_bytes[i]; |
222 | cur->bsr_stride = bsr_stride[i]; | |
a0e2f9f4 | 223 | cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); |
fe9e8d53 | 224 | |
04a85d12 SR |
225 | /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */ |
226 | /* we can only map 4k of it, so only advertise the 4k in sysfs */ | |
227 | if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE) | |
228 | cur->bsr_len = 4096; | |
229 | ||
fe9e8d53 SR |
230 | switch(cur->bsr_bytes) { |
231 | case 8: | |
232 | cur->bsr_type = BSR_8; | |
233 | break; | |
234 | case 16: | |
235 | cur->bsr_type = BSR_16; | |
236 | break; | |
237 | case 64: | |
238 | cur->bsr_type = BSR_64; | |
239 | break; | |
240 | case 128: | |
241 | cur->bsr_type = BSR_128; | |
242 | break; | |
e4031d52 SR |
243 | case 4096: |
244 | cur->bsr_type = BSR_4096; | |
245 | break; | |
fe9e8d53 SR |
246 | default: |
247 | cur->bsr_type = BSR_UNKNOWN; | |
fe9e8d53 SR |
248 | } |
249 | ||
250 | cur->bsr_num = bsr_types[cur->bsr_type]; | |
fe9e8d53 SR |
251 | snprintf(cur->bsr_name, 32, "bsr%d_%d", |
252 | cur->bsr_bytes, cur->bsr_num); | |
253 | ||
254 | cdev_init(&cur->bsr_cdev, &bsr_fops); | |
255 | result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1); | |
a0e2f9f4 SR |
256 | if (result) { |
257 | kfree(cur); | |
fe9e8d53 | 258 | goto out_err; |
a0e2f9f4 | 259 | } |
fe9e8d53 | 260 | |
03457cd4 GKH |
261 | cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, |
262 | cur, cur->bsr_name); | |
30c96ce5 | 263 | if (IS_ERR(cur->bsr_device)) { |
fe9e8d53 SR |
264 | printk(KERN_ERR "device_create failed for %s\n", |
265 | cur->bsr_name); | |
266 | cdev_del(&cur->bsr_cdev); | |
a0e2f9f4 | 267 | kfree(cur); |
fe9e8d53 SR |
268 | goto out_err; |
269 | } | |
a0e2f9f4 SR |
270 | |
271 | bsr_types[cur->bsr_type] = cur->bsr_num + 1; | |
272 | list_add_tail(&cur->bsr_list, &bsr_devs); | |
fe9e8d53 SR |
273 | } |
274 | ||
a0e2f9f4 SR |
275 | total_bsr_devs += num_bsr_devs; |
276 | ||
fe9e8d53 SR |
277 | return 0; |
278 | ||
279 | out_err: | |
280 | ||
281 | bsr_cleanup_devs(); | |
a0e2f9f4 SR |
282 | return ret; |
283 | } | |
284 | ||
285 | static int bsr_create_devs(struct device_node *bn) | |
286 | { | |
287 | int ret; | |
288 | ||
289 | while (bn) { | |
290 | ret = bsr_add_node(bn); | |
291 | if (ret) { | |
292 | of_node_put(bn); | |
293 | return ret; | |
294 | } | |
295 | bn = of_find_compatible_node(bn, NULL, "ibm,bsr"); | |
296 | } | |
297 | return 0; | |
fe9e8d53 SR |
298 | } |
299 | ||
300 | static int __init bsr_init(void) | |
301 | { | |
302 | struct device_node *np; | |
cce36444 | 303 | dev_t bsr_dev; |
fe9e8d53 | 304 | int ret = -ENODEV; |
fe9e8d53 | 305 | |
a0e2f9f4 | 306 | np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); |
fe9e8d53 SR |
307 | if (!np) |
308 | goto out_err; | |
309 | ||
310 | bsr_class = class_create(THIS_MODULE, "bsr"); | |
311 | if (IS_ERR(bsr_class)) { | |
312 | printk(KERN_ERR "class_create() failed for bsr_class\n"); | |
8397c76a | 313 | ret = PTR_ERR(bsr_class); |
fe9e8d53 SR |
314 | goto out_err_1; |
315 | } | |
62e13505 | 316 | bsr_class->dev_groups = bsr_dev_groups; |
fe9e8d53 | 317 | |
8397c76a | 318 | ret = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr"); |
fe9e8d53 | 319 | bsr_major = MAJOR(bsr_dev); |
8397c76a | 320 | if (ret < 0) { |
fe9e8d53 SR |
321 | printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n"); |
322 | goto out_err_2; | |
323 | } | |
324 | ||
a0e2f9f4 SR |
325 | if ((ret = bsr_create_devs(np)) < 0) { |
326 | np = NULL; | |
fe9e8d53 | 327 | goto out_err_3; |
a0e2f9f4 | 328 | } |
fe9e8d53 SR |
329 | |
330 | return 0; | |
331 | ||
332 | out_err_3: | |
333 | unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS); | |
334 | ||
335 | out_err_2: | |
336 | class_destroy(bsr_class); | |
337 | ||
338 | out_err_1: | |
339 | of_node_put(np); | |
340 | ||
341 | out_err: | |
342 | ||
343 | return ret; | |
344 | } | |
345 | ||
346 | static void __exit bsr_exit(void) | |
347 | { | |
348 | ||
349 | bsr_cleanup_devs(); | |
350 | ||
351 | if (bsr_class) | |
352 | class_destroy(bsr_class); | |
353 | ||
354 | if (bsr_major) | |
355 | unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS); | |
356 | } | |
357 | ||
358 | module_init(bsr_init); | |
359 | module_exit(bsr_exit); | |
360 | MODULE_LICENSE("GPL"); | |
361 | MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); |