drivers/char/ipmi/ssif_bmc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * The driver for BMC side of SSIF interface
   4  *
   5  * Copyright (c) 2022, Ampere Computing LLC
   6  *
   7  */
   8
   9 #include <linux/i2c.h>
  10 #include <linux/miscdevice.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/poll.h>
  15 #include <linux/sched.h>
  16 #include <linux/mutex.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/timer.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/ipmi_ssif_bmc.h>
  21
  22 #define DEVICE_NAME                             "ipmi-ssif-host"
  23
  24 #define GET_8BIT_ADDR(addr_7bit)                (((addr_7bit) << 1) & 0xff)
  25
  26 /* A standard SMBus Transaction is limited to 32 data bytes */
  27 #define MAX_PAYLOAD_PER_TRANSACTION             32
  28 /* Transaction includes the address, the command, the length and the PEC byte */
  29 #define MAX_TRANSACTION                         (MAX_PAYLOAD_PER_TRANSACTION + 4)
  30
  31 #define MAX_IPMI_DATA_PER_START_TRANSACTION     30
  32 #define MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION    31
  33
  34 #define SSIF_IPMI_SINGLEPART_WRITE              0x2
  35 #define SSIF_IPMI_SINGLEPART_READ               0x3
  36 #define SSIF_IPMI_MULTIPART_WRITE_START         0x6
  37 #define SSIF_IPMI_MULTIPART_WRITE_MIDDLE        0x7
  38 #define SSIF_IPMI_MULTIPART_WRITE_END           0x8
  39 #define SSIF_IPMI_MULTIPART_READ_START          0x3
  40 #define SSIF_IPMI_MULTIPART_READ_MIDDLE         0x9
  41
  42 /*
  43  * IPMI 2.0 Spec, section 12.7 SSIF Timing,
  44  * Request-to-Response Time is T6max(250ms) - T1max(20ms) - 3ms = 227ms
  45  * Recover ssif_bmc from busy state if it takes up to 500ms
  46  */
  47 #define RESPONSE_TIMEOUT                        500 /* ms */
  48
  49 struct ssif_part_buffer {
  50         u8 address;
  51         u8 smbus_cmd;
  52         u8 length;
  53         u8 payload[MAX_PAYLOAD_PER_TRANSACTION];
  54         u8 pec;
  55         u8 index;
  56 };
  57
  58 /*
  59  * SSIF internal states:
  60  *   SSIF_READY         0x00 : Ready state
  61  *   SSIF_START         0x01 : Start smbus transaction
  62  *   SSIF_SMBUS_CMD     0x02 : Received SMBus command
  63  *   SSIF_REQ_RECVING   0x03 : Receiving request
  64  *   SSIF_RES_SENDING   0x04 : Sending response
  65  *   SSIF_ABORTING      0x05 : Aborting state
  66  */
  67 enum ssif_state {
  68         SSIF_READY,
  69         SSIF_START,
  70         SSIF_SMBUS_CMD,
  71         SSIF_REQ_RECVING,
  72         SSIF_RES_SENDING,
  73         SSIF_ABORTING,
  74         SSIF_STATE_MAX
  75 };
  76
  77 struct ssif_bmc_ctx {
  78         struct i2c_client       *client;
  79         struct miscdevice       miscdev;
  80         int                     msg_idx;
  81         bool                    pec_support;
  82         /* ssif bmc spinlock */
  83         spinlock_t              lock;
  84         wait_queue_head_t       wait_queue;
  85         u8                      running;
  86         enum ssif_state         state;
  87         /* Timeout waiting for response */
  88         struct timer_list       response_timer;
  89         bool                    response_timer_inited;
  90         /* Flag to identify a Multi-part Read Transaction */
  91         bool                    is_singlepart_read;
  92         u8                      nbytes_processed;
  93         u8                      remain_len;
  94         u8                      recv_len;
  95         /* Block Number of a Multi-part Read Transaction */
  96         u8                      block_num;
  97         bool                    request_available;
  98         bool                    response_in_progress;
  99         bool                    busy;
 100         bool                    aborting;
 101         /* Buffer for SSIF Transaction part*/
 102         struct ssif_part_buffer part_buf;
 103         struct ipmi_ssif_msg    response;
 104         struct ipmi_ssif_msg    request;
 105 };
 106
 107 static inline struct ssif_bmc_ctx *to_ssif_bmc(struct file *file)
 108 {
 109         return container_of(file->private_data, struct ssif_bmc_ctx, miscdev);
 110 }
 111
 112 static const char *state_to_string(enum ssif_state state)
 113 {
 114         switch (state) {
 115         case SSIF_READY:
 116                 return "SSIF_READY";
 117         case SSIF_START:
 118                 return "SSIF_START";
 119         case SSIF_SMBUS_CMD:
 120                 return "SSIF_SMBUS_CMD";
 121         case SSIF_REQ_RECVING:
 122                 return "SSIF_REQ_RECVING";
 123         case SSIF_RES_SENDING:
 124                 return "SSIF_RES_SENDING";
 125         case SSIF_ABORTING:
 126                 return "SSIF_ABORTING";
 127         default:
 128                 return "SSIF_STATE_UNKNOWN";
 129         }
 130 }
 131
 132 /* Handle SSIF message that will be sent to user */
 133 static ssize_t ssif_bmc_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 134 {
 135         struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
 136         struct ipmi_ssif_msg msg;
 137         unsigned long flags;
 138         ssize_t ret;
 139
 140         spin_lock_irqsave(&ssif_bmc->lock, flags);
 141         while (!ssif_bmc->request_available) {
 142                 spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 143                 if (file->f_flags & O_NONBLOCK)
 144                         return -EAGAIN;
 145                 ret = wait_event_interruptible(ssif_bmc->wait_queue,
 146                                                ssif_bmc->request_available);
 147                 if (ret)
 148                         return ret;
 149                 spin_lock_irqsave(&ssif_bmc->lock, flags);
 150         }
 151
 152         if (count < min_t(ssize_t,
 153                           sizeof_field(struct ipmi_ssif_msg, len) + ssif_bmc->request.len,
 154                           sizeof(struct ipmi_ssif_msg))) {
 155                 spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 156                 ret = -EINVAL;
 157         } else {
 158                 count = min_t(ssize_t,
 159                               sizeof_field(struct ipmi_ssif_msg, len) + ssif_bmc->request.len,
 160                               sizeof(struct ipmi_ssif_msg));
 161                 memcpy(&msg, &ssif_bmc->request, count);
 162                 ssif_bmc->request_available = false;
 163                 spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 164
 165                 ret = copy_to_user(buf, &msg, count);
 166         }
 167
 168         return (ret < 0) ? ret : count;
 169 }
 170
 171 /* Handle SSIF message that is written by user */
 172 static ssize_t ssif_bmc_write(struct file *file, const char __user *buf, size_t count,
 173                               loff_t *ppos)
 174 {
 175         struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
 176         struct ipmi_ssif_msg msg;
 177         unsigned long flags;
 178         ssize_t ret;
 179
 180         if (count > sizeof(struct ipmi_ssif_msg))
 181                 return -EINVAL;
 182
 183         if (copy_from_user(&msg, buf, count))
 184                 return -EFAULT;
 185
 186         if (!msg.len || count < sizeof_field(struct ipmi_ssif_msg, len) + msg.len)
 187                 return -EINVAL;
 188
 189         spin_lock_irqsave(&ssif_bmc->lock, flags);
 190         while (ssif_bmc->response_in_progress) {
 191                 spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 192                 if (file->f_flags & O_NONBLOCK)
 193                         return -EAGAIN;
 194                 ret = wait_event_interruptible(ssif_bmc->wait_queue,
 195                                                !ssif_bmc->response_in_progress);
 196                 if (ret)
 197                         return ret;
 198                 spin_lock_irqsave(&ssif_bmc->lock, flags);
 199         }
 200
 201         /*
 202          * The write must complete before the response timeout fired, otherwise
 203          * the response is aborted and wait for next request
 204          * Return -EINVAL if the response is aborted
 205          */
 206         ret = (ssif_bmc->response_timer_inited) ? 0 : -EINVAL;
 207         if (ret)
 208                 goto exit;
 209
 210         del_timer(&ssif_bmc->response_timer);
 211         ssif_bmc->response_timer_inited = false;
 212
 213         memcpy(&ssif_bmc->response, &msg, count);
 214         ssif_bmc->is_singlepart_read = (msg.len <= MAX_PAYLOAD_PER_TRANSACTION);
 215
 216         ssif_bmc->response_in_progress = true;
 217
 218         /* ssif_bmc not busy */
 219         ssif_bmc->busy = false;
 220
 221         /* Clean old request buffer */
 222         memset(&ssif_bmc->request, 0, sizeof(struct ipmi_ssif_msg));
 223 exit:
 224         spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 225
 226         return (ret < 0) ? ret : count;
 227 }
 228
 229 static int ssif_bmc_open(struct inode *inode, struct file *file)
 230 {
 231         struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
 232         int ret = 0;
 233
 234         spin_lock_irq(&ssif_bmc->lock);
 235         if (!ssif_bmc->running)
 236                 ssif_bmc->running = 1;
 237         else
 238                 ret = -EBUSY;
 239         spin_unlock_irq(&ssif_bmc->lock);
 240
 241         return ret;
 242 }
 243
 244 static __poll_t ssif_bmc_poll(struct file *file, poll_table *wait)
 245 {
 246         struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
 247         __poll_t mask = 0;
 248
 249         poll_wait(file, &ssif_bmc->wait_queue, wait);
 250
 251         spin_lock_irq(&ssif_bmc->lock);
 252         /* The request is available, userspace application can get the request */
 253         if (ssif_bmc->request_available)
 254                 mask |= EPOLLIN;
 255
 256         spin_unlock_irq(&ssif_bmc->lock);
 257
 258         return mask;
 259 }
 260
 261 static int ssif_bmc_release(struct inode *inode, struct file *file)
 262 {
 263         struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
 264
 265         spin_lock_irq(&ssif_bmc->lock);
 266         ssif_bmc->running = 0;
 267         spin_unlock_irq(&ssif_bmc->lock);
 268
 269         return 0;
 270 }
 271
 272 /*
 273  * System calls to device interface for user apps
 274  */
 275 static const struct file_operations ssif_bmc_fops = {
 276         .owner          = THIS_MODULE,
 277         .open           = ssif_bmc_open,
 278         .read           = ssif_bmc_read,
 279         .write          = ssif_bmc_write,
 280         .release        = ssif_bmc_release,
 281         .poll           = ssif_bmc_poll,
 282 };
 283
 284 /* Called with ssif_bmc->lock held. */
 285 static void complete_response(struct ssif_bmc_ctx *ssif_bmc)
 286 {
 287         /* Invalidate response in buffer to denote it having been sent. */
 288         ssif_bmc->response.len = 0;
 289         ssif_bmc->response_in_progress = false;
 290         ssif_bmc->nbytes_processed = 0;
 291         ssif_bmc->remain_len = 0;
 292         ssif_bmc->busy = false;
 293         memset(&ssif_bmc->part_buf, 0, sizeof(struct ssif_part_buffer));
 294         wake_up_all(&ssif_bmc->wait_queue);
 295 }
 296
 297 static void response_timeout(struct timer_list *t)
 298 {
 299         struct ssif_bmc_ctx *ssif_bmc = from_timer(ssif_bmc, t, response_timer);
 300         unsigned long flags;
 301
 302         spin_lock_irqsave(&ssif_bmc->lock, flags);
 303
 304         /* Do nothing if the response is in progress */
 305         if (!ssif_bmc->response_in_progress) {
 306                 /* Recover ssif_bmc from busy */
 307                 ssif_bmc->busy = false;
 308                 ssif_bmc->response_timer_inited = false;
 309                 /* Set aborting flag */
 310                 ssif_bmc->aborting = true;
 311         }
 312
 313         spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 314 }
 315
 316 /* Called with ssif_bmc->lock held. */
 317 static void handle_request(struct ssif_bmc_ctx *ssif_bmc)
 318 {
 319         /* set ssif_bmc to busy waiting for response */
 320         ssif_bmc->busy = true;
 321         /* Request message is available to process */
 322         ssif_bmc->request_available = true;
 323         /* Clean old response buffer */
 324         memset(&ssif_bmc->response, 0, sizeof(struct ipmi_ssif_msg));
 325         /* This is the new READ request.*/
 326         wake_up_all(&ssif_bmc->wait_queue);
 327
 328         /* Armed timer to recover slave from busy state in case of no response */
 329         if (!ssif_bmc->response_timer_inited) {
 330                 timer_setup(&ssif_bmc->response_timer, response_timeout, 0);
 331                 ssif_bmc->response_timer_inited = true;
 332         }
 333         mod_timer(&ssif_bmc->response_timer, jiffies + msecs_to_jiffies(RESPONSE_TIMEOUT));
 334 }
 335
 336 static void calculate_response_part_pec(struct ssif_part_buffer *part)
 337 {
 338         u8 addr = part->address;
 339
 340         /* PEC - Start Read Address */
 341         part->pec = i2c_smbus_pec(0, &addr, 1);
 342         /* PEC - SSIF Command */
 343         part->pec = i2c_smbus_pec(part->pec, &part->smbus_cmd, 1);
 344         /* PEC - Restart Write Address */
 345         addr = addr | 0x01;
 346         part->pec = i2c_smbus_pec(part->pec, &addr, 1);
 347         part->pec = i2c_smbus_pec(part->pec, &part->length, 1);
 348         if (part->length)
 349                 part->pec = i2c_smbus_pec(part->pec, part->payload, part->length);
 350 }
 351
 352 static void set_singlepart_response_buffer(struct ssif_bmc_ctx *ssif_bmc)
 353 {
 354         struct ssif_part_buffer *part = &ssif_bmc->part_buf;
 355
 356         part->address = GET_8BIT_ADDR(ssif_bmc->client->addr);
 357         part->length = (u8)ssif_bmc->response.len;
 358
 359         /* Clear the rest to 0 */
 360         memset(part->payload + part->length, 0, MAX_PAYLOAD_PER_TRANSACTION - part->length);
 361         memcpy(&part->payload[0], &ssif_bmc->response.payload[0], part->length);
 362 }
 363
 364 static void set_multipart_response_buffer(struct ssif_bmc_ctx *ssif_bmc)
 365 {
 366         struct ssif_part_buffer *part = &ssif_bmc->part_buf;
 367         u8 part_len = 0;
 368
 369         part->address = GET_8BIT_ADDR(ssif_bmc->client->addr);
 370         switch (part->smbus_cmd) {
 371         case SSIF_IPMI_MULTIPART_READ_START:
 372                 /*
 373                  * Read Start length is 32 bytes.
 374                  * Read Start transfer first 30 bytes of IPMI response
 375                  * and 2 special code 0x00, 0x01.
 376                  */
 377                 ssif_bmc->nbytes_processed = 0;
 378                 ssif_bmc->block_num = 0;
 379                 part->length = MAX_PAYLOAD_PER_TRANSACTION;
 380                 part_len = MAX_IPMI_DATA_PER_START_TRANSACTION;
 381                 ssif_bmc->remain_len = ssif_bmc->response.len - part_len;
 382
 383                 part->payload[0] = 0x00; /* Start Flag */
 384                 part->payload[1] = 0x01; /* Start Flag */
 385
 386                 memcpy(&part->payload[2], &ssif_bmc->response.payload[0], part_len);
 387                 break;
 388
 389         case SSIF_IPMI_MULTIPART_READ_MIDDLE:
 390                 /*
 391                  * IPMI READ Middle or READ End messages can carry up to 31 bytes
 392                  * IPMI data plus block number byte.
 393                  */
 394                 if (ssif_bmc->remain_len <= MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION) {
 395                         /*
 396                          * This is READ End message
 397                          *  Return length is the remaining response data length
 398                          *  plus block number
 399                          *  Block number 0xFF is to indicate this is last message
 400                          *
 401                          */
 402                         /* Clean the buffer */
 403                         memset(&part->payload[0], 0, MAX_PAYLOAD_PER_TRANSACTION);
 404                         part->length = ssif_bmc->remain_len + 1;
 405                         part_len = ssif_bmc->remain_len;
 406                         ssif_bmc->block_num = 0xFF;
 407                         part->payload[0] = ssif_bmc->block_num;
 408                 } else {
 409                         /*
 410                          * This is READ Middle message
 411                          *  Response length is the maximum SMBUS transfer length
 412                          *  Block number byte is incremented
 413                          * Return length is maximum SMBUS transfer length
 414                          */
 415                         part->length = MAX_PAYLOAD_PER_TRANSACTION;
 416                         part_len = MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION;
 417                         part->payload[0] = ssif_bmc->block_num;
 418                         ssif_bmc->block_num++;
 419                 }
 420
 421                 ssif_bmc->remain_len -= part_len;
 422                 memcpy(&part->payload[1], ssif_bmc->response.payload + ssif_bmc->nbytes_processed,
 423                        part_len);
 424                 break;
 425
 426         default:
 427                 /* Do not expect to go to this case */
 428                 dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n",
 429                         __func__, part->smbus_cmd);
 430                 break;
 431         }
 432
 433         ssif_bmc->nbytes_processed += part_len;
 434 }
 435
 436 static bool supported_read_cmd(u8 cmd)
 437 {
 438         if (cmd == SSIF_IPMI_SINGLEPART_READ ||
 439             cmd == SSIF_IPMI_MULTIPART_READ_START ||
 440             cmd == SSIF_IPMI_MULTIPART_READ_MIDDLE)
 441                 return true;
 442
 443         return false;
 444 }
 445
 446 static bool supported_write_cmd(u8 cmd)
 447 {
 448         if (cmd == SSIF_IPMI_SINGLEPART_WRITE ||
 449             cmd == SSIF_IPMI_MULTIPART_WRITE_START ||
 450             cmd == SSIF_IPMI_MULTIPART_WRITE_MIDDLE ||
 451             cmd == SSIF_IPMI_MULTIPART_WRITE_END)
 452                 return true;
 453
 454         return false;
 455 }
 456
 457 /* Process the IPMI response that will be read by master */
 458 static void handle_read_processed(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 459 {
 460         struct ssif_part_buffer *part = &ssif_bmc->part_buf;
 461
 462         /* msg_idx start from 0 */
 463         if (part->index < part->length)
 464                 *val = part->payload[part->index];
 465         else if (part->index == part->length && ssif_bmc->pec_support)
 466                 *val = part->pec;
 467         else
 468                 *val = 0;
 469
 470         part->index++;
 471 }
 472
 473 static void handle_write_received(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 474 {
 475         /*
 476          * The msg_idx must be 1 when first enter SSIF_REQ_RECVING state
 477          * And it would never exceeded 36 bytes included the 32 bytes max payload +
 478          * the address + the command + the len and the PEC.
 479          */
 480         if (ssif_bmc->msg_idx < 1  || ssif_bmc->msg_idx > MAX_TRANSACTION)
 481                 return;
 482
 483         if (ssif_bmc->msg_idx == 1) {
 484                 ssif_bmc->part_buf.length = *val;
 485                 ssif_bmc->part_buf.index = 0;
 486         } else {
 487                 ssif_bmc->part_buf.payload[ssif_bmc->part_buf.index++] = *val;
 488         }
 489
 490         ssif_bmc->msg_idx++;
 491 }
 492
 493 static bool validate_request_part(struct ssif_bmc_ctx *ssif_bmc)
 494 {
 495         struct ssif_part_buffer *part = &ssif_bmc->part_buf;
 496         bool ret = true;
 497         u8 cpec;
 498         u8 addr;
 499
 500         if (part->index == part->length) {
 501                 /* PEC is not included */
 502                 ssif_bmc->pec_support = false;
 503                 ret = true;
 504                 goto exit;
 505         }
 506
 507         if (part->index != part->length + 1) {
 508                 ret = false;
 509                 goto exit;
 510         }
 511
 512         /* PEC is included */
 513         ssif_bmc->pec_support = true;
 514         part->pec = part->payload[part->length];
 515         addr = GET_8BIT_ADDR(ssif_bmc->client->addr);
 516         cpec = i2c_smbus_pec(0, &addr, 1);
 517         cpec = i2c_smbus_pec(cpec, &part->smbus_cmd, 1);
 518         cpec = i2c_smbus_pec(cpec, &part->length, 1);
 519         /*
 520          * As SMBus specification does not allow the length
 521          * (byte count) in the Write-Block protocol to be zero.
 522          * Therefore, it is illegal to have the last Middle
 523          * transaction in the sequence carry 32-byte and have
 524          * a length of ‘0’ in the End transaction.
 525          * But some users may try to use this way and we should
 526          * prevent ssif_bmc driver broken in this case.
 527          */
 528         if (part->length)
 529                 cpec = i2c_smbus_pec(cpec, part->payload, part->length);
 530
 531         if (cpec != part->pec)
 532                 ret = false;
 533
 534 exit:
 535         return ret;
 536 }
 537
 538 static void process_request_part(struct ssif_bmc_ctx *ssif_bmc)
 539 {
 540         struct ssif_part_buffer *part = &ssif_bmc->part_buf;
 541         unsigned int len;
 542
 543         switch (part->smbus_cmd) {
 544         case SSIF_IPMI_SINGLEPART_WRITE:
 545                 /* save the whole part to request*/
 546                 ssif_bmc->request.len = part->length;
 547                 memcpy(ssif_bmc->request.payload, part->payload, part->length);
 548
 549                 break;
 550         case SSIF_IPMI_MULTIPART_WRITE_START:
 551                 ssif_bmc->request.len = 0;
 552
 553                 fallthrough;
 554         case SSIF_IPMI_MULTIPART_WRITE_MIDDLE:
 555         case SSIF_IPMI_MULTIPART_WRITE_END:
 556                 len = ssif_bmc->request.len + part->length;
 557                 /* Do the bound check here, not allow the request len exceed 254 bytes */
 558                 if (len > IPMI_SSIF_PAYLOAD_MAX) {
 559                         dev_warn(&ssif_bmc->client->dev,
 560                                  "Warn: Request exceeded 254 bytes, aborting");
 561                         /* Request too long, aborting */
 562                         ssif_bmc->aborting =  true;
 563                 } else {
 564                         memcpy(ssif_bmc->request.payload + ssif_bmc->request.len,
 565                                part->payload, part->length);
 566                         ssif_bmc->request.len += part->length;
 567                 }
 568                 break;
 569         default:
 570                 /* Do not expect to go to this case */
 571                 dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n",
 572                         __func__, part->smbus_cmd);
 573                 break;
 574         }
 575 }
 576
 577 static void process_smbus_cmd(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 578 {
 579         /* SMBUS command can vary (single or multi-part) */
 580         ssif_bmc->part_buf.smbus_cmd = *val;
 581         ssif_bmc->msg_idx = 1;
 582         memset(&ssif_bmc->part_buf.payload[0], 0, MAX_PAYLOAD_PER_TRANSACTION);
 583
 584         if (*val == SSIF_IPMI_SINGLEPART_WRITE || *val == SSIF_IPMI_MULTIPART_WRITE_START) {
 585                 /*
 586                  * The response maybe not come in-time, causing host SSIF driver
 587                  * to timeout and resend a new request. In such case check for
 588                  * pending response and clear it
 589                  */
 590                 if (ssif_bmc->response_in_progress)
 591                         complete_response(ssif_bmc);
 592
 593                 /* This is new request, flip aborting flag if set */
 594                 if (ssif_bmc->aborting)
 595                         ssif_bmc->aborting = false;
 596         }
 597 }
 598
 599 static void on_read_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 600 {
 601         if (ssif_bmc->state == SSIF_READY ||
 602             ssif_bmc->state == SSIF_START ||
 603             ssif_bmc->state == SSIF_REQ_RECVING ||
 604             ssif_bmc->state == SSIF_RES_SENDING) {
 605                 dev_warn(&ssif_bmc->client->dev,
 606                          "Warn: %s unexpected READ REQUESTED in state=%s\n",
 607                          __func__, state_to_string(ssif_bmc->state));
 608                 ssif_bmc->state = SSIF_ABORTING;
 609                 *val = 0;
 610                 return;
 611
 612         } else if (ssif_bmc->state == SSIF_SMBUS_CMD) {
 613                 if (!supported_read_cmd(ssif_bmc->part_buf.smbus_cmd)) {
 614                         dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus read command=0x%x",
 615                                  ssif_bmc->part_buf.smbus_cmd);
 616                         ssif_bmc->aborting = true;
 617                 }
 618
 619                 if (ssif_bmc->aborting)
 620                         ssif_bmc->state = SSIF_ABORTING;
 621                 else
 622                         ssif_bmc->state = SSIF_RES_SENDING;
 623         }
 624
 625         ssif_bmc->msg_idx = 0;
 626
 627         /* Send 0 if there is nothing to send */
 628         if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) {
 629                 *val = 0;
 630                 return;
 631         }
 632
 633         if (ssif_bmc->is_singlepart_read)
 634                 set_singlepart_response_buffer(ssif_bmc);
 635         else
 636                 set_multipart_response_buffer(ssif_bmc);
 637
 638         calculate_response_part_pec(&ssif_bmc->part_buf);
 639         ssif_bmc->part_buf.index = 0;
 640         *val = ssif_bmc->part_buf.length;
 641 }
 642
 643 static void on_read_processed_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 644 {
 645         if (ssif_bmc->state == SSIF_READY ||
 646             ssif_bmc->state == SSIF_START ||
 647             ssif_bmc->state == SSIF_REQ_RECVING ||
 648             ssif_bmc->state == SSIF_SMBUS_CMD) {
 649                 dev_warn(&ssif_bmc->client->dev,
 650                          "Warn: %s unexpected READ PROCESSED in state=%s\n",
 651                          __func__, state_to_string(ssif_bmc->state));
 652                 ssif_bmc->state = SSIF_ABORTING;
 653                 *val = 0;
 654                 return;
 655         }
 656
 657         /* Send 0 if there is nothing to send */
 658         if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) {
 659                 *val = 0;
 660                 return;
 661         }
 662
 663         handle_read_processed(ssif_bmc, val);
 664 }
 665
 666 static void on_write_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 667 {
 668         if (ssif_bmc->state == SSIF_READY || ssif_bmc->state == SSIF_SMBUS_CMD) {
 669                 ssif_bmc->state = SSIF_START;
 670
 671         } else if (ssif_bmc->state == SSIF_START ||
 672                    ssif_bmc->state == SSIF_REQ_RECVING ||
 673                    ssif_bmc->state == SSIF_RES_SENDING) {
 674                 dev_warn(&ssif_bmc->client->dev,
 675                          "Warn: %s unexpected WRITE REQUEST in state=%s\n",
 676                          __func__, state_to_string(ssif_bmc->state));
 677                 ssif_bmc->state = SSIF_ABORTING;
 678                 return;
 679         }
 680
 681         ssif_bmc->msg_idx = 0;
 682         ssif_bmc->part_buf.address = *val;
 683 }
 684
 685 static void on_write_received_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 686 {
 687         if (ssif_bmc->state == SSIF_READY ||
 688             ssif_bmc->state == SSIF_RES_SENDING) {
 689                 dev_warn(&ssif_bmc->client->dev,
 690                          "Warn: %s unexpected WRITE RECEIVED in state=%s\n",
 691                          __func__, state_to_string(ssif_bmc->state));
 692                 ssif_bmc->state = SSIF_ABORTING;
 693
 694         } else if (ssif_bmc->state == SSIF_START) {
 695                 ssif_bmc->state = SSIF_SMBUS_CMD;
 696
 697         } else if (ssif_bmc->state == SSIF_SMBUS_CMD) {
 698                 if (!supported_write_cmd(ssif_bmc->part_buf.smbus_cmd)) {
 699                         dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus write command=0x%x",
 700                                  ssif_bmc->part_buf.smbus_cmd);
 701                         ssif_bmc->aborting = true;
 702                 }
 703
 704                 if (ssif_bmc->aborting)
 705                         ssif_bmc->state = SSIF_ABORTING;
 706                 else
 707                         ssif_bmc->state = SSIF_REQ_RECVING;
 708         }
 709
 710         /* This is response sending state */
 711         if (ssif_bmc->state == SSIF_REQ_RECVING)
 712                 handle_write_received(ssif_bmc, val);
 713         else if (ssif_bmc->state == SSIF_SMBUS_CMD)
 714                 process_smbus_cmd(ssif_bmc, val);
 715 }
 716
 717 static void on_stop_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
 718 {
 719         if (ssif_bmc->state == SSIF_READY ||
 720             ssif_bmc->state == SSIF_START ||
 721             ssif_bmc->state == SSIF_SMBUS_CMD ||
 722             ssif_bmc->state == SSIF_ABORTING) {
 723                 dev_warn(&ssif_bmc->client->dev,
 724                          "Warn: %s unexpected SLAVE STOP in state=%s\n",
 725                          __func__, state_to_string(ssif_bmc->state));
 726                 ssif_bmc->state = SSIF_READY;
 727
 728         } else if (ssif_bmc->state == SSIF_REQ_RECVING) {
 729                 if (validate_request_part(ssif_bmc)) {
 730                         process_request_part(ssif_bmc);
 731                         if (ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_SINGLEPART_WRITE ||
 732                             ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_MULTIPART_WRITE_END)
 733                                 handle_request(ssif_bmc);
 734                         ssif_bmc->state = SSIF_READY;
 735                 } else {
 736                         /*
 737                          * A BMC that receives an invalid request drop the data for the write
 738                          * transaction and any further transactions (read or write) until
 739                          * the next valid read or write Start transaction is received
 740                          */
 741                         dev_err(&ssif_bmc->client->dev, "Error: invalid pec\n");
 742                         ssif_bmc->aborting = true;
 743                 }
 744         } else if (ssif_bmc->state == SSIF_RES_SENDING) {
 745                 if (ssif_bmc->is_singlepart_read || ssif_bmc->block_num == 0xFF)
 746                         /* Invalidate response buffer to denote it is sent */
 747                         complete_response(ssif_bmc);
 748                 ssif_bmc->state = SSIF_READY;
 749         }
 750
 751         /* Reset message index */
 752         ssif_bmc->msg_idx = 0;
 753 }
 754
 755 /*
 756  * Callback function to handle I2C slave events
 757  */
 758 static int ssif_bmc_cb(struct i2c_client *client, enum i2c_slave_event event, u8 *val)
 759 {
 760         unsigned long flags;
 761         struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client);
 762         int ret = 0;
 763
 764         spin_lock_irqsave(&ssif_bmc->lock, flags);
 765
 766         switch (event) {
 767         case I2C_SLAVE_READ_REQUESTED:
 768                 on_read_requested_event(ssif_bmc, val);
 769                 break;
 770
 771         case I2C_SLAVE_WRITE_REQUESTED:
 772                 on_write_requested_event(ssif_bmc, val);
 773                 break;
 774
 775         case I2C_SLAVE_READ_PROCESSED:
 776                 on_read_processed_event(ssif_bmc, val);
 777                 break;
 778
 779         case I2C_SLAVE_WRITE_RECEIVED:
 780                 on_write_received_event(ssif_bmc, val);
 781                 break;
 782
 783         case I2C_SLAVE_STOP:
 784                 on_stop_event(ssif_bmc, val);
 785                 break;
 786
 787         default:
 788                 dev_warn(&ssif_bmc->client->dev, "Warn: Unknown i2c slave event\n");
 789                 break;
 790         }
 791
 792         if (!ssif_bmc->aborting && ssif_bmc->busy)
 793                 ret = -EBUSY;
 794
 795         spin_unlock_irqrestore(&ssif_bmc->lock, flags);
 796
 797         return ret;
 798 }
 799
 800 static int ssif_bmc_probe(struct i2c_client *client)
 801 {
 802         struct ssif_bmc_ctx *ssif_bmc;
 803         int ret;
 804
 805         ssif_bmc = devm_kzalloc(&client->dev, sizeof(*ssif_bmc), GFP_KERNEL);
 806         if (!ssif_bmc)
 807                 return -ENOMEM;
 808
 809         spin_lock_init(&ssif_bmc->lock);
 810
 811         init_waitqueue_head(&ssif_bmc->wait_queue);
 812         ssif_bmc->request_available = false;
 813         ssif_bmc->response_in_progress = false;
 814         ssif_bmc->busy = false;
 815         ssif_bmc->response_timer_inited = false;
 816
 817         /* Register misc device interface */
 818         ssif_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
 819         ssif_bmc->miscdev.name = DEVICE_NAME;
 820         ssif_bmc->miscdev.fops = &ssif_bmc_fops;
 821         ssif_bmc->miscdev.parent = &client->dev;
 822         ret = misc_register(&ssif_bmc->miscdev);
 823         if (ret)
 824                 return ret;
 825
 826         ssif_bmc->client = client;
 827         ssif_bmc->client->flags |= I2C_CLIENT_SLAVE;
 828
 829         /* Register I2C slave */
 830         i2c_set_clientdata(client, ssif_bmc);
 831         ret = i2c_slave_register(client, ssif_bmc_cb);
 832         if (ret)
 833                 misc_deregister(&ssif_bmc->miscdev);
 834
 835         return ret;
 836 }
 837
 838 static void ssif_bmc_remove(struct i2c_client *client)
 839 {
 840         struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client);
 841
 842         i2c_slave_unregister(client);
 843         misc_deregister(&ssif_bmc->miscdev);
 844 }
 845
 846 static const struct of_device_id ssif_bmc_match[] = {
 847         { .compatible = "ssif-bmc" },
 848         { },
 849 };
 850 MODULE_DEVICE_TABLE(of, ssif_bmc_match);
 851
 852 static const struct i2c_device_id ssif_bmc_id[] = {
 853         { DEVICE_NAME, 0 },
 854         { },
 855 };
 856 MODULE_DEVICE_TABLE(i2c, ssif_bmc_id);
 857
 858 static struct i2c_driver ssif_bmc_driver = {
 859         .driver         = {
 860                 .name           = DEVICE_NAME,
 861                 .of_match_table = ssif_bmc_match,
 862         },
 863         .probe          = ssif_bmc_probe,
 864         .remove         = ssif_bmc_remove,
 865         .id_table       = ssif_bmc_id,
 866 };
 867
 868 module_i2c_driver(ssif_bmc_driver);
 869
 870 MODULE_AUTHOR("Quan Nguyen <quan@os.amperecomputing.com>");
 871 MODULE_AUTHOR("Chuong Tran <chuong@os.amperecomputing.com>");
 872 MODULE_DESCRIPTION("Linux device driver of the BMC IPMI SSIF interface.");
 873 MODULE_LICENSE("GPL");