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/fs.h> 27#include <linux/module.h> 28#include <linux/cdev.h> 29#include <linux/list.h> 30#include <linux/mm.h> 31#include <linux/slab.h> 32#include <asm/pgtable.h> 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 57struct 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 66 struct list_head bsr_list; 67 68 dev_t bsr_dev; 69 struct cdev bsr_cdev; 70 struct device *bsr_device; 71 char bsr_name[32]; 72 73}; 74 75static unsigned total_bsr_devs; 76static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs); 77static struct class *bsr_class; 78static int bsr_major; 79 80enum { 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, 88}; 89 90static unsigned bsr_types[BSR_MAX]; 91 92static ssize_t 93bsr_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 99static ssize_t 100bsr_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 106static ssize_t 107bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf) 108{ 109 struct bsr_dev *bsr_dev = dev_get_drvdata(dev); 110 return sprintf(buf, "%llu\n", bsr_dev->bsr_len); 111} 112 113static 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 120static 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; 124 int ret; 125 126 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 127 128 /* 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) 140 return -EAGAIN; 141 142 return 0; 143} 144 145static 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 154static const struct file_operations bsr_fops = { 155 .owner = THIS_MODULE, 156 .mmap = bsr_mmap, 157 .open = bsr_open, 158}; 159 160static void bsr_cleanup_devs(void) 161{ 162 struct bsr_dev *cur, *n; 163 164 list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) { 165 if (cur->bsr_device) { 166 cdev_del(&cur->bsr_cdev); 167 device_del(cur->bsr_device); 168 } 169 list_del(&cur->bsr_list); 170 kfree(cur); 171 } 172} 173 174static int bsr_add_node(struct device_node *bn) 175{ 176 int bsr_stride_len, bsr_bytes_len, num_bsr_devs; 177 const u32 *bsr_stride; 178 const u32 *bsr_bytes; 179 unsigned i; 180 int ret = -ENODEV; 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"); 188 return ret; 189 } 190 191 num_bsr_devs = bsr_bytes_len / sizeof(u32); 192 193 for (i = 0 ; i < num_bsr_devs; i++) { 194 struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev), 195 GFP_KERNEL); 196 struct resource res; 197 int result; 198 199 if (!cur) { 200 printk(KERN_ERR "Unable to alloc bsr dev\n"); 201 ret = -ENOMEM; 202 goto out_err; 203 } 204 205 result = of_address_to_resource(bn, i, &res); 206 if (result < 0) { 207 printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n"); 208 kfree(cur); 209 continue; 210 } 211 212 cur->bsr_minor = i + total_bsr_devs; 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]; 217 cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs); 218 219 /* 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; 223 224 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; 237 case 4096: 238 cur->bsr_type = BSR_4096; 239 break; 240 default: 241 cur->bsr_type = BSR_UNKNOWN; 242 } 243 244 cur->bsr_num = bsr_types[cur->bsr_type]; 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); 250 if (result) { 251 kfree(cur); 252 goto out_err; 253 } 254 255 cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev, 256 cur, cur->bsr_name); 257 if (IS_ERR(cur->bsr_device)) { 258 printk(KERN_ERR "device_create failed for %s\n", 259 cur->bsr_name); 260 cdev_del(&cur->bsr_cdev); 261 kfree(cur); 262 goto out_err; 263 } 264 265 bsr_types[cur->bsr_type] = cur->bsr_num + 1; 266 list_add_tail(&cur->bsr_list, &bsr_devs); 267 } 268 269 total_bsr_devs += num_bsr_devs; 270 271 return 0; 272 273 out_err: 274 275 bsr_cleanup_devs(); 276 return ret; 277} 278 279static 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; 292} 293 294static 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; 300 301 np = of_find_compatible_node(NULL, NULL, "ibm,bsr"); 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 } 318 319 if ((ret = bsr_create_devs(np)) < 0) { 320 np = NULL; 321 goto out_err_3; 322 } 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 340static 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 352module_init(bsr_init); 353module_exit(bsr_exit); 354MODULE_LICENSE("GPL"); 355MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>"); 356