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1a59d1b8 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
fe9e8d53 SR |
2 | /* IBM POWER Barrier Synchronization Register Driver |
3 | * | |
4 | * Copyright IBM Corporation 2008 | |
5 | * | |
6 | * Author: Sonny Rao <sonnyrao@us.ibm.com> | |
fe9e8d53 SR |
7 | */ |
8 | ||
9 | #include <linux/kernel.h> | |
10 | #include <linux/of.h> | |
5af50730 | 11 | #include <linux/of_address.h> |
fe9e8d53 SR |
12 | #include <linux/of_device.h> |
13 | #include <linux/of_platform.h> | |
22ae782f | 14 | #include <linux/fs.h> |
fe9e8d53 SR |
15 | #include <linux/module.h> |
16 | #include <linux/cdev.h> | |
17 | #include <linux/list.h> | |
18 | #include <linux/mm.h> | |
5a0e3ad6 | 19 | #include <linux/slab.h> |
04a85d12 | 20 | #include <asm/pgtable.h> |
fe9e8d53 SR |
21 | #include <asm/io.h> |
22 | ||
23 | /* | |
24 | This driver exposes a special register which can be used for fast | |
25 | synchronization across a large SMP machine. The hardware is exposed | |
26 | as an array of bytes where each process will write to one of the bytes to | |
27 | indicate it has finished the current stage and this update is broadcast to | |
28 | all processors without having to bounce a cacheline between them. In | |
29 | POWER5 and POWER6 there is one of these registers per SMP, but it is | |
30 | presented in two forms; first, it is given as a whole and then as a number | |
31 | of smaller registers which alias to parts of the single whole register. | |
32 | This can potentially allow multiple groups of processes to each have their | |
33 | own private synchronization device. | |
34 | ||
35 | Note that this hardware *must* be written to using *only* single byte writes. | |
36 | It may be read using 1, 2, 4, or 8 byte loads which must be aligned since | |
37 | this region is treated as cache-inhibited processes should also use a | |
38 | full sync before and after writing to the BSR to ensure all stores and | |
39 | the BSR update have made it to all chips in the system | |
40 | */ | |
41 | ||
42 | /* This is arbitrary number, up to Power6 it's been 17 or fewer */ | |
43 | #define BSR_MAX_DEVS (32) | |
44 | ||
45 | struct bsr_dev { | |
46 | u64 bsr_addr; /* Real address */ | |
47 | u64 bsr_len; /* length of mem region we can map */ | |
48 | unsigned bsr_bytes; /* size of the BSR reg itself */ | |
49 | unsigned bsr_stride; /* interval at which BSR repeats in the page */ | |
50 | unsigned bsr_type; /* maps to enum below */ | |
51 | unsigned bsr_num; /* bsr id number for its type */ | |
52 | int bsr_minor; | |
53 | ||
a0e2f9f4 SR |
54 | struct list_head bsr_list; |
55 | ||
fe9e8d53 SR |
56 | dev_t bsr_dev; |
57 | struct cdev bsr_cdev; | |
58 | struct device *bsr_device; | |
59 | char bsr_name[32]; | |
60 | ||
61 | }; | |
62 | ||
a0e2f9f4 SR |
63 | static unsigned total_bsr_devs; |
64 | static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); | |
fe9e8d53 SR |
65 | static struct class *bsr_class; |
66 | static int bsr_major; | |
67 | ||
68 | enum { | |
e4031d52 SR |
69 | BSR_8 = 0, |
70 | BSR_16 = 1, | |
71 | BSR_64 = 2, | |
72 | BSR_128 = 3, | |
73 | BSR_4096 = 4, | |
74 | BSR_UNKNOWN = 5, | |
75 | BSR_MAX = 6, | |
fe9e8d53 SR |
76 | }; |
77 | ||
78 | static unsigned bsr_types[BSR_MAX]; | |
79 | ||
80 | static ssize_t | |
81 | bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf) | |
82 | { | |
83 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
84 | return sprintf(buf, "%u\n", bsr_dev->bsr_bytes); | |
85 | } | |
62e13505 | 86 | static DEVICE_ATTR_RO(bsr_size); |
fe9e8d53 SR |
87 | |
88 | static ssize_t | |
89 | bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf) | |
90 | { | |
91 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
92 | return sprintf(buf, "%u\n", bsr_dev->bsr_stride); | |
93 | } | |
62e13505 | 94 | static DEVICE_ATTR_RO(bsr_stride); |
fe9e8d53 SR |
95 | |
96 | static ssize_t | |
62e13505 | 97 | bsr_length_show(struct device *dev, struct device_attribute *attr, char *buf) |
fe9e8d53 SR |
98 | { |
99 | struct bsr_dev *bsr_dev = dev_get_drvdata(dev); | |
1901515c | 100 | return sprintf(buf, "%llu\n", bsr_dev->bsr_len); |
fe9e8d53 | 101 | } |
62e13505 | 102 | static DEVICE_ATTR_RO(bsr_length); |
fe9e8d53 | 103 | |
62e13505 GKH |
104 | static struct attribute *bsr_dev_attrs[] = { |
105 | &dev_attr_bsr_size.attr, | |
106 | &dev_attr_bsr_stride.attr, | |
107 | &dev_attr_bsr_length.attr, | |
108 | NULL, | |
fe9e8d53 | 109 | }; |
62e13505 | 110 | ATTRIBUTE_GROUPS(bsr_dev); |
fe9e8d53 SR |
111 | |
112 | static int bsr_mmap(struct file *filp, struct vm_area_struct *vma) | |
113 | { | |
114 | unsigned long size = vma->vm_end - vma->vm_start; | |
115 | struct bsr_dev *dev = filp->private_data; | |
04a85d12 | 116 | int ret; |
fe9e8d53 | 117 | |
fe9e8d53 SR |
118 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
119 | ||
04a85d12 SR |
120 | /* check for the case of a small BSR device and map one 4k page for it*/ |
121 | if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE) | |
122 | ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12, | |
123 | vma->vm_page_prot); | |
124 | else if (size <= dev->bsr_len) | |
125 | ret = io_remap_pfn_range(vma, vma->vm_start, | |
126 | dev->bsr_addr >> PAGE_SHIFT, | |
127 | size, vma->vm_page_prot); | |
128 | else | |
129 | return -EINVAL; | |
130 | ||
131 | if (ret) | |
fe9e8d53 SR |
132 | return -EAGAIN; |
133 | ||
134 | return 0; | |
135 | } | |
136 | ||
687685a3 | 137 | static int bsr_open(struct inode *inode, struct file *filp) |
fe9e8d53 SR |
138 | { |
139 | struct cdev *cdev = inode->i_cdev; | |
140 | struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev); | |
141 | ||
142 | filp->private_data = dev; | |
143 | return 0; | |
144 | } | |
145 | ||
27157a70 | 146 | static const struct file_operations bsr_fops = { |
fe9e8d53 SR |
147 | .owner = THIS_MODULE, |
148 | .mmap = bsr_mmap, | |
149 | .open = bsr_open, | |
6038f373 | 150 | .llseek = noop_llseek, |
fe9e8d53 SR |
151 | }; |
152 | ||
153 | static void bsr_cleanup_devs(void) | |
154 | { | |
a0e2f9f4 SR |
155 | struct bsr_dev *cur, *n; |
156 | ||
157 | list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { | |
fe9e8d53 SR |
158 | if (cur->bsr_device) { |
159 | cdev_del(&cur->bsr_cdev); | |
160 | device_del(cur->bsr_device); | |
161 | } | |
a0e2f9f4 SR |
162 | list_del(&cur->bsr_list); |
163 | kfree(cur); | |
fe9e8d53 | 164 | } |
fe9e8d53 SR |
165 | } |
166 | ||
a0e2f9f4 | 167 | static int bsr_add_node(struct device_node *bn) |
fe9e8d53 | 168 | { |
a0e2f9f4 | 169 | int bsr_stride_len, bsr_bytes_len, num_bsr_devs; |
fe9e8d53 SR |
170 | const u32 *bsr_stride; |
171 | const u32 *bsr_bytes; | |
172 | unsigned i; | |
a0e2f9f4 | 173 | int ret = -ENODEV; |
fe9e8d53 SR |
174 | |
175 | bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len); | |
176 | bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len); | |
177 | ||
178 | if (!bsr_stride || !bsr_bytes || | |
179 | (bsr_stride_len != bsr_bytes_len)) { | |
180 | printk(KERN_ERR "bsr of-node has missing/incorrect property\n"); | |
a0e2f9f4 | 181 | return ret; |
fe9e8d53 SR |
182 | } |
183 | ||
184 | num_bsr_devs = bsr_bytes_len / sizeof(u32); | |
185 | ||
fe9e8d53 | 186 | for (i = 0 ; i < num_bsr_devs; i++) { |
a0e2f9f4 SR |
187 | struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), |
188 | GFP_KERNEL); | |
fe9e8d53 SR |
189 | struct resource res; |
190 | int result; | |
191 | ||
a0e2f9f4 SR |
192 | if (!cur) { |
193 | printk(KERN_ERR "Unable to alloc bsr dev\n"); | |
194 | ret = -ENOMEM; | |
195 | goto out_err; | |
196 | } | |
197 | ||
fe9e8d53 SR |
198 | result = of_address_to_resource(bn, i, &res); |
199 | if (result < 0) { | |
a0e2f9f4 SR |
200 | printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); |
201 | kfree(cur); | |
202 | continue; | |
fe9e8d53 SR |
203 | } |
204 | ||
a0e2f9f4 | 205 | cur->bsr_minor = i + total_bsr_devs; |
fe9e8d53 | 206 | cur->bsr_addr = res.start; |
28f65c11 | 207 | cur->bsr_len = resource_size(&res); |
fe9e8d53 SR |
208 | cur->bsr_bytes = bsr_bytes[i]; |
209 | cur->bsr_stride = bsr_stride[i]; | |
a0e2f9f4 | 210 | cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); |
fe9e8d53 | 211 | |
04a85d12 SR |
212 | /* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */ |
213 | /* we can only map 4k of it, so only advertise the 4k in sysfs */ | |
214 | if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE) | |
215 | cur->bsr_len = 4096; | |
216 | ||
fe9e8d53 SR |
217 | switch(cur->bsr_bytes) { |
218 | case 8: | |
219 | cur->bsr_type = BSR_8; | |
220 | break; | |
221 | case 16: | |
222 | cur->bsr_type = BSR_16; | |
223 | break; | |
224 | case 64: | |
225 | cur->bsr_type = BSR_64; | |
226 | break; | |
227 | case 128: | |
228 | cur->bsr_type = BSR_128; | |
229 | break; | |
e4031d52 SR |
230 | case 4096: |
231 | cur->bsr_type = BSR_4096; | |
232 | break; | |
fe9e8d53 SR |
233 | default: |
234 | cur->bsr_type = BSR_UNKNOWN; | |
fe9e8d53 SR |
235 | } |
236 | ||
237 | cur->bsr_num = bsr_types[cur->bsr_type]; | |
fe9e8d53 SR |
238 | snprintf(cur->bsr_name, 32, "bsr%d_%d", |
239 | cur->bsr_bytes, cur->bsr_num); | |
240 | ||
241 | cdev_init(&cur->bsr_cdev, &bsr_fops); | |
242 | result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1); | |
a0e2f9f4 SR |
243 | if (result) { |
244 | kfree(cur); | |
fe9e8d53 | 245 | goto out_err; |
a0e2f9f4 | 246 | } |
fe9e8d53 | 247 | |
03457cd4 | 248 | cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, |
4171ee9e | 249 | cur, "%s", cur->bsr_name); |
30c96ce5 | 250 | if (IS_ERR(cur->bsr_device)) { |
fe9e8d53 SR |
251 | printk(KERN_ERR "device_create failed for %s\n", |
252 | cur->bsr_name); | |
253 | cdev_del(&cur->bsr_cdev); | |
a0e2f9f4 | 254 | kfree(cur); |
fe9e8d53 SR |
255 | goto out_err; |
256 | } | |
a0e2f9f4 SR |
257 | |
258 | bsr_types[cur->bsr_type] = cur->bsr_num + 1; | |
259 | list_add_tail(&cur->bsr_list, &bsr_devs); | |
fe9e8d53 SR |
260 | } |
261 | ||
a0e2f9f4 SR |
262 | total_bsr_devs += num_bsr_devs; |
263 | ||
fe9e8d53 SR |
264 | return 0; |
265 | ||
266 | out_err: | |
267 | ||
268 | bsr_cleanup_devs(); | |
a0e2f9f4 SR |
269 | return ret; |
270 | } | |
271 | ||
272 | static int bsr_create_devs(struct device_node *bn) | |
273 | { | |
274 | int ret; | |
275 | ||
276 | while (bn) { | |
277 | ret = bsr_add_node(bn); | |
278 | if (ret) { | |
279 | of_node_put(bn); | |
280 | return ret; | |
281 | } | |
282 | bn = of_find_compatible_node(bn, NULL, "ibm,bsr"); | |
283 | } | |
284 | return 0; | |
fe9e8d53 SR |
285 | } |
286 | ||
287 | static int __init bsr_init(void) | |
288 | { | |
289 | struct device_node *np; | |
cce36444 | 290 | dev_t bsr_dev; |
fe9e8d53 | 291 | int ret = -ENODEV; |
fe9e8d53 | 292 | |
a0e2f9f4 | 293 | np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); |
fe9e8d53 SR |
294 | if (!np) |
295 | goto out_err; | |
296 | ||
297 | bsr_class = class_create(THIS_MODULE, "bsr"); | |
298 | if (IS_ERR(bsr_class)) { | |
299 | printk(KERN_ERR "class_create() failed for bsr_class\n"); | |
8397c76a | 300 | ret = PTR_ERR(bsr_class); |
fe9e8d53 SR |
301 | goto out_err_1; |
302 | } | |
62e13505 | 303 | bsr_class->dev_groups = bsr_dev_groups; |
fe9e8d53 | 304 | |
8397c76a | 305 | ret = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr"); |
fe9e8d53 | 306 | bsr_major = MAJOR(bsr_dev); |
8397c76a | 307 | if (ret < 0) { |
fe9e8d53 SR |
308 | printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n"); |
309 | goto out_err_2; | |
310 | } | |
311 | ||
7256d7f4 NKP |
312 | ret = bsr_create_devs(np); |
313 | if (ret < 0) { | |
a0e2f9f4 | 314 | np = NULL; |
fe9e8d53 | 315 | goto out_err_3; |
a0e2f9f4 | 316 | } |
fe9e8d53 SR |
317 | |
318 | return 0; | |
319 | ||
320 | out_err_3: | |
321 | unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS); | |
322 | ||
323 | out_err_2: | |
324 | class_destroy(bsr_class); | |
325 | ||
326 | out_err_1: | |
327 | of_node_put(np); | |
328 | ||
329 | out_err: | |
330 | ||
331 | return ret; | |
332 | } | |
333 | ||
334 | static void __exit bsr_exit(void) | |
335 | { | |
336 | ||
337 | bsr_cleanup_devs(); | |
338 | ||
339 | if (bsr_class) | |
340 | class_destroy(bsr_class); | |
341 | ||
342 | if (bsr_major) | |
343 | unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS); | |
344 | } | |
345 | ||
346 | module_init(bsr_init); | |
347 | module_exit(bsr_exit); | |
348 | MODULE_LICENSE("GPL"); | |
349 | MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); |