drivers/misc/ibmasm/ibmasmfs.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IBM ASM Service Processor Device Driver
   4  *
   5  * Copyright (C) IBM Corporation, 2004
   6  *
   7  * Author: Max Asböck <amax@us.ibm.com>
   8  */
   9
  10 /*
  11  * Parts of this code are based on an article by Jonathan Corbet
  12  * that appeared in Linux Weekly News.
  13  */
  14
  15
  16 /*
  17  * The IBMASM file virtual filesystem. It creates the following hierarchy
  18  * dynamically when mounted from user space:
  19  *
  20  *    /ibmasm
  21  *    |-- 0
  22  *    |   |-- command
  23  *    |   |-- event
  24  *    |   |-- reverse_heartbeat
  25  *    |   `-- remote_video
  26  *    |       |-- depth
  27  *    |       |-- height
  28  *    |       `-- width
  29  *    .
  30  *    .
  31  *    .
  32  *    `-- n
  33  *        |-- command
  34  *        |-- event
  35  *        |-- reverse_heartbeat
  36  *        `-- remote_video
  37  *            |-- depth
  38  *            |-- height
  39  *            `-- width
  40  *
  41  * For each service processor the following files are created:
  42  *
  43  * command: execute dot commands
  44  *      write: execute a dot command on the service processor
  45  *      read: return the result of a previously executed dot command
  46  *
  47  * events: listen for service processor events
  48  *      read: sleep (interruptible) until an event occurs
  49  *      write: wakeup sleeping event listener
  50  *
  51  * reverse_heartbeat: send a heartbeat to the service processor
  52  *      read: sleep (interruptible) until the reverse heartbeat fails
  53  *      write: wakeup sleeping heartbeat listener
  54  *
  55  * remote_video/width
  56  * remote_video/height
  57  * remote_video/width: control remote display settings
  58  *      write: set value
  59  *      read: read value
  60  */
  61
  62 #include <linux/fs.h>
  63 #include <linux/pagemap.h>
  64 #include <linux/slab.h>
  65 #include <linux/uaccess.h>
  66 #include <asm/io.h>
  67 #include "ibmasm.h"
  68 #include "remote.h"
  69 #include "dot_command.h"
  70
  71 #define IBMASMFS_MAGIC 0x66726f67
  72
  73 static LIST_HEAD(service_processors);
  74
  75 static struct inode *ibmasmfs_make_inode(struct super_block *sb, int mode);
  76 static void ibmasmfs_create_files (struct super_block *sb);
  77 static int ibmasmfs_fill_super (struct super_block *sb, void *data, int silent);
  78
  79
  80 static struct dentry *ibmasmfs_mount(struct file_system_type *fst,
  81                         int flags, const char *name, void *data)
  82 {
  83         return mount_single(fst, flags, data, ibmasmfs_fill_super);
  84 }
  85
  86 static const struct super_operations ibmasmfs_s_ops = {
  87         .statfs         = simple_statfs,
  88         .drop_inode     = generic_delete_inode,
  89 };
  90
  91 static const struct file_operations *ibmasmfs_dir_ops = &simple_dir_operations;
  92
  93 static struct file_system_type ibmasmfs_type = {
  94         .owner          = THIS_MODULE,
  95         .name           = "ibmasmfs",
  96         .mount          = ibmasmfs_mount,
  97         .kill_sb        = kill_litter_super,
  98 };
  99 MODULE_ALIAS_FS("ibmasmfs");
 100
 101 static int ibmasmfs_fill_super (struct super_block *sb, void *data, int silent)
 102 {
 103         struct inode *root;
 104
 105         sb->s_blocksize = PAGE_SIZE;
 106         sb->s_blocksize_bits = PAGE_SHIFT;
 107         sb->s_magic = IBMASMFS_MAGIC;
 108         sb->s_op = &ibmasmfs_s_ops;
 109         sb->s_time_gran = 1;
 110
 111         root = ibmasmfs_make_inode (sb, S_IFDIR | 0500);
 112         if (!root)
 113                 return -ENOMEM;
 114
 115         root->i_op = &simple_dir_inode_operations;
 116         root->i_fop = ibmasmfs_dir_ops;
 117
 118         sb->s_root = d_make_root(root);
 119         if (!sb->s_root)
 120                 return -ENOMEM;
 121
 122         ibmasmfs_create_files(sb);
 123         return 0;
 124 }
 125
 126 static struct inode *ibmasmfs_make_inode(struct super_block *sb, int mode)
 127 {
 128         struct inode *ret = new_inode(sb);
 129
 130         if (ret) {
 131                 ret->i_ino = get_next_ino();
 132                 ret->i_mode = mode;
 133                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 134         }
 135         return ret;
 136 }
 137
 138 static struct dentry *ibmasmfs_create_file(struct dentry *parent,
 139                         const char *name,
 140                         const struct file_operations *fops,
 141                         void *data,
 142                         int mode)
 143 {
 144         struct dentry *dentry;
 145         struct inode *inode;
 146
 147         dentry = d_alloc_name(parent, name);
 148         if (!dentry)
 149                 return NULL;
 150
 151         inode = ibmasmfs_make_inode(parent->d_sb, S_IFREG | mode);
 152         if (!inode) {
 153                 dput(dentry);
 154                 return NULL;
 155         }
 156
 157         inode->i_fop = fops;
 158         inode->i_private = data;
 159
 160         d_add(dentry, inode);
 161         return dentry;
 162 }
 163
 164 static struct dentry *ibmasmfs_create_dir(struct dentry *parent,
 165                                 const char *name)
 166 {
 167         struct dentry *dentry;
 168         struct inode *inode;
 169
 170         dentry = d_alloc_name(parent, name);
 171         if (!dentry)
 172                 return NULL;
 173
 174         inode = ibmasmfs_make_inode(parent->d_sb, S_IFDIR | 0500);
 175         if (!inode) {
 176                 dput(dentry);
 177                 return NULL;
 178         }
 179
 180         inode->i_op = &simple_dir_inode_operations;
 181         inode->i_fop = ibmasmfs_dir_ops;
 182
 183         d_add(dentry, inode);
 184         return dentry;
 185 }
 186
 187 int ibmasmfs_register(void)
 188 {
 189         return register_filesystem(&ibmasmfs_type);
 190 }
 191
 192 void ibmasmfs_unregister(void)
 193 {
 194         unregister_filesystem(&ibmasmfs_type);
 195 }
 196
 197 void ibmasmfs_add_sp(struct service_processor *sp)
 198 {
 199         list_add(&sp->node, &service_processors);
 200 }
 201
 202 /* struct to save state between command file operations */
 203 struct ibmasmfs_command_data {
 204         struct service_processor        *sp;
 205         struct command                  *command;
 206 };
 207
 208 /* struct to save state between event file operations */
 209 struct ibmasmfs_event_data {
 210         struct service_processor        *sp;
 211         struct event_reader             reader;
 212         int                             active;
 213 };
 214
 215 /* struct to save state between reverse heartbeat file operations */
 216 struct ibmasmfs_heartbeat_data {
 217         struct service_processor        *sp;
 218         struct reverse_heartbeat        heartbeat;
 219         int                             active;
 220 };
 221
 222 static int command_file_open(struct inode *inode, struct file *file)
 223 {
 224         struct ibmasmfs_command_data *command_data;
 225
 226         if (!inode->i_private)
 227                 return -ENODEV;
 228
 229         command_data = kmalloc(sizeof(struct ibmasmfs_command_data), GFP_KERNEL);
 230         if (!command_data)
 231                 return -ENOMEM;
 232
 233         command_data->command = NULL;
 234         command_data->sp = inode->i_private;
 235         file->private_data = command_data;
 236         return 0;
 237 }
 238
 239 static int command_file_close(struct inode *inode, struct file *file)
 240 {
 241         struct ibmasmfs_command_data *command_data = file->private_data;
 242
 243         if (command_data->command)
 244                 command_put(command_data->command);
 245
 246         kfree(command_data);
 247         return 0;
 248 }
 249
 250 static ssize_t command_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
 251 {
 252         struct ibmasmfs_command_data *command_data = file->private_data;
 253         struct command *cmd;
 254         int len;
 255         unsigned long flags;
 256
 257         if (*offset < 0)
 258                 return -EINVAL;
 259         if (count == 0 || count > IBMASM_CMD_MAX_BUFFER_SIZE)
 260                 return 0;
 261         if (*offset != 0)
 262                 return 0;
 263
 264         spin_lock_irqsave(&command_data->sp->lock, flags);
 265         cmd = command_data->command;
 266         if (cmd == NULL) {
 267                 spin_unlock_irqrestore(&command_data->sp->lock, flags);
 268                 return 0;
 269         }
 270         command_data->command = NULL;
 271         spin_unlock_irqrestore(&command_data->sp->lock, flags);
 272
 273         if (cmd->status != IBMASM_CMD_COMPLETE) {
 274                 command_put(cmd);
 275                 return -EIO;
 276         }
 277         len = min(count, cmd->buffer_size);
 278         if (copy_to_user(buf, cmd->buffer, len)) {
 279                 command_put(cmd);
 280                 return -EFAULT;
 281         }
 282         command_put(cmd);
 283
 284         return len;
 285 }
 286
 287 static ssize_t command_file_write(struct file *file, const char __user *ubuff, size_t count, loff_t *offset)
 288 {
 289         struct ibmasmfs_command_data *command_data = file->private_data;
 290         struct command *cmd;
 291         unsigned long flags;
 292
 293         if (*offset < 0)
 294                 return -EINVAL;
 295         if (count == 0 || count > IBMASM_CMD_MAX_BUFFER_SIZE)
 296                 return 0;
 297         if (*offset != 0)
 298                 return 0;
 299
 300         /* commands are executed sequentially, only one command at a time */
 301         if (command_data->command)
 302                 return -EAGAIN;
 303
 304         cmd = ibmasm_new_command(command_data->sp, count);
 305         if (!cmd)
 306                 return -ENOMEM;
 307
 308         if (copy_from_user(cmd->buffer, ubuff, count)) {
 309                 command_put(cmd);
 310                 return -EFAULT;
 311         }
 312
 313         spin_lock_irqsave(&command_data->sp->lock, flags);
 314         if (command_data->command) {
 315                 spin_unlock_irqrestore(&command_data->sp->lock, flags);
 316                 command_put(cmd);
 317                 return -EAGAIN;
 318         }
 319         command_data->command = cmd;
 320         spin_unlock_irqrestore(&command_data->sp->lock, flags);
 321
 322         ibmasm_exec_command(command_data->sp, cmd);
 323         ibmasm_wait_for_response(cmd, get_dot_command_timeout(cmd->buffer));
 324
 325         return count;
 326 }
 327
 328 static int event_file_open(struct inode *inode, struct file *file)
 329 {
 330         struct ibmasmfs_event_data *event_data;
 331         struct service_processor *sp;
 332
 333         if (!inode->i_private)
 334                 return -ENODEV;
 335
 336         sp = inode->i_private;
 337
 338         event_data = kmalloc(sizeof(struct ibmasmfs_event_data), GFP_KERNEL);
 339         if (!event_data)
 340                 return -ENOMEM;
 341
 342         ibmasm_event_reader_register(sp, &event_data->reader);
 343
 344         event_data->sp = sp;
 345         event_data->active = 0;
 346         file->private_data = event_data;
 347         return 0;
 348 }
 349
 350 static int event_file_close(struct inode *inode, struct file *file)
 351 {
 352         struct ibmasmfs_event_data *event_data = file->private_data;
 353
 354         ibmasm_event_reader_unregister(event_data->sp, &event_data->reader);
 355         kfree(event_data);
 356         return 0;
 357 }
 358
 359 static ssize_t event_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
 360 {
 361         struct ibmasmfs_event_data *event_data = file->private_data;
 362         struct event_reader *reader = &event_data->reader;
 363         struct service_processor *sp = event_data->sp;
 364         int ret;
 365         unsigned long flags;
 366
 367         if (*offset < 0)
 368                 return -EINVAL;
 369         if (count == 0 || count > IBMASM_EVENT_MAX_SIZE)
 370                 return 0;
 371         if (*offset != 0)
 372                 return 0;
 373
 374         spin_lock_irqsave(&sp->lock, flags);
 375         if (event_data->active) {
 376                 spin_unlock_irqrestore(&sp->lock, flags);
 377                 return -EBUSY;
 378         }
 379         event_data->active = 1;
 380         spin_unlock_irqrestore(&sp->lock, flags);
 381
 382         ret = ibmasm_get_next_event(sp, reader);
 383         if (ret <= 0)
 384                 goto out;
 385
 386         if (count < reader->data_size) {
 387                 ret = -EINVAL;
 388                 goto out;
 389         }
 390
 391         if (copy_to_user(buf, reader->data, reader->data_size)) {
 392                 ret = -EFAULT;
 393                 goto out;
 394         }
 395         ret = reader->data_size;
 396
 397 out:
 398         event_data->active = 0;
 399         return ret;
 400 }
 401
 402 static ssize_t event_file_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
 403 {
 404         struct ibmasmfs_event_data *event_data = file->private_data;
 405
 406         if (*offset < 0)
 407                 return -EINVAL;
 408         if (count != 1)
 409                 return 0;
 410         if (*offset != 0)
 411                 return 0;
 412
 413         ibmasm_cancel_next_event(&event_data->reader);
 414         return 0;
 415 }
 416
 417 static int r_heartbeat_file_open(struct inode *inode, struct file *file)
 418 {
 419         struct ibmasmfs_heartbeat_data *rhbeat;
 420
 421         if (!inode->i_private)
 422                 return -ENODEV;
 423
 424         rhbeat = kmalloc(sizeof(struct ibmasmfs_heartbeat_data), GFP_KERNEL);
 425         if (!rhbeat)
 426                 return -ENOMEM;
 427
 428         rhbeat->sp = inode->i_private;
 429         rhbeat->active = 0;
 430         ibmasm_init_reverse_heartbeat(rhbeat->sp, &rhbeat->heartbeat);
 431         file->private_data = rhbeat;
 432         return 0;
 433 }
 434
 435 static int r_heartbeat_file_close(struct inode *inode, struct file *file)
 436 {
 437         struct ibmasmfs_heartbeat_data *rhbeat = file->private_data;
 438
 439         kfree(rhbeat);
 440         return 0;
 441 }
 442
 443 static ssize_t r_heartbeat_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
 444 {
 445         struct ibmasmfs_heartbeat_data *rhbeat = file->private_data;
 446         unsigned long flags;
 447         int result;
 448
 449         if (*offset < 0)
 450                 return -EINVAL;
 451         if (count == 0 || count > 1024)
 452                 return 0;
 453         if (*offset != 0)
 454                 return 0;
 455
 456         /* allow only one reverse heartbeat per process */
 457         spin_lock_irqsave(&rhbeat->sp->lock, flags);
 458         if (rhbeat->active) {
 459                 spin_unlock_irqrestore(&rhbeat->sp->lock, flags);
 460                 return -EBUSY;
 461         }
 462         rhbeat->active = 1;
 463         spin_unlock_irqrestore(&rhbeat->sp->lock, flags);
 464
 465         result = ibmasm_start_reverse_heartbeat(rhbeat->sp, &rhbeat->heartbeat);
 466         rhbeat->active = 0;
 467
 468         return result;
 469 }
 470
 471 static ssize_t r_heartbeat_file_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
 472 {
 473         struct ibmasmfs_heartbeat_data *rhbeat = file->private_data;
 474
 475         if (*offset < 0)
 476                 return -EINVAL;
 477         if (count != 1)
 478                 return 0;
 479         if (*offset != 0)
 480                 return 0;
 481
 482         if (rhbeat->active)
 483                 ibmasm_stop_reverse_heartbeat(&rhbeat->heartbeat);
 484
 485         return 1;
 486 }
 487
 488 static int remote_settings_file_close(struct inode *inode, struct file *file)
 489 {
 490         return 0;
 491 }
 492
 493 static ssize_t remote_settings_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
 494 {
 495         void __iomem *address = (void __iomem *)file->private_data;
 496         int len = 0;
 497         unsigned int value;
 498         char lbuf[20];
 499
 500         value = readl(address);
 501         len = snprintf(lbuf, sizeof(lbuf), "%d\n", value);
 502
 503         return simple_read_from_buffer(buf, count, offset, lbuf, len);
 504 }
 505
 506 static ssize_t remote_settings_file_write(struct file *file, const char __user *ubuff, size_t count, loff_t *offset)
 507 {
 508         void __iomem *address = (void __iomem *)file->private_data;
 509         char *buff;
 510         unsigned int value;
 511
 512         if (*offset < 0)
 513                 return -EINVAL;
 514         if (count == 0 || count > 1024)
 515                 return 0;
 516         if (*offset != 0)
 517                 return 0;
 518
 519         buff = kzalloc (count + 1, GFP_KERNEL);
 520         if (!buff)
 521                 return -ENOMEM;
 522
 523
 524         if (copy_from_user(buff, ubuff, count)) {
 525                 kfree(buff);
 526                 return -EFAULT;
 527         }
 528
 529         value = simple_strtoul(buff, NULL, 10);
 530         writel(value, address);
 531         kfree(buff);
 532
 533         return count;
 534 }
 535
 536 static const struct file_operations command_fops = {
 537         .open =         command_file_open,
 538         .release =      command_file_close,
 539         .read =         command_file_read,
 540         .write =        command_file_write,
 541         .llseek =       generic_file_llseek,
 542 };
 543
 544 static const struct file_operations event_fops = {
 545         .open =         event_file_open,
 546         .release =      event_file_close,
 547         .read =         event_file_read,
 548         .write =        event_file_write,
 549         .llseek =       generic_file_llseek,
 550 };
 551
 552 static const struct file_operations r_heartbeat_fops = {
 553         .open =         r_heartbeat_file_open,
 554         .release =      r_heartbeat_file_close,
 555         .read =         r_heartbeat_file_read,
 556         .write =        r_heartbeat_file_write,
 557         .llseek =       generic_file_llseek,
 558 };
 559
 560 static const struct file_operations remote_settings_fops = {
 561         .open =         simple_open,
 562         .release =      remote_settings_file_close,
 563         .read =         remote_settings_file_read,
 564         .write =        remote_settings_file_write,
 565         .llseek =       generic_file_llseek,
 566 };
 567
 568
 569 static void ibmasmfs_create_files (struct super_block *sb)
 570 {
 571         struct list_head *entry;
 572         struct service_processor *sp;
 573
 574         list_for_each(entry, &service_processors) {
 575                 struct dentry *dir;
 576                 struct dentry *remote_dir;
 577                 sp = list_entry(entry, struct service_processor, node);
 578                 dir = ibmasmfs_create_dir(sb->s_root, sp->dirname);
 579                 if (!dir)
 580                         continue;
 581
 582                 ibmasmfs_create_file(dir, "command", &command_fops, sp, S_IRUSR|S_IWUSR);
 583                 ibmasmfs_create_file(dir, "event", &event_fops, sp, S_IRUSR|S_IWUSR);
 584                 ibmasmfs_create_file(dir, "reverse_heartbeat", &r_heartbeat_fops, sp, S_IRUSR|S_IWUSR);
 585
 586                 remote_dir = ibmasmfs_create_dir(dir, "remote_video");
 587                 if (!remote_dir)
 588                         continue;
 589
 590                 ibmasmfs_create_file(remote_dir, "width", &remote_settings_fops, (void *)display_width(sp), S_IRUSR|S_IWUSR);
 591                 ibmasmfs_create_file(remote_dir, "height", &remote_settings_fops, (void *)display_height(sp), S_IRUSR|S_IWUSR);
 592                 ibmasmfs_create_file(remote_dir, "depth", &remote_settings_fops, (void *)display_depth(sp), S_IRUSR|S_IWUSR);
 593         }
 594 }