drivers/char/ipmi/bt-bmc.c

   1 /*
   2  * Copyright (c) 2015-2016, IBM Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/atomic.h>
  11 #include <linux/bt-bmc.h>
  12 #include <linux/errno.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/io.h>
  15 #include <linux/mfd/syscon.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/poll.h>
  21 #include <linux/regmap.h>
  22 #include <linux/sched.h>
  23 #include <linux/timer.h>
  24
  25 /*
  26  * This is a BMC device used to communicate to the host
  27  */
  28 #define DEVICE_NAME     "ipmi-bt-host"
  29
  30 #define BT_IO_BASE      0xe4
  31 #define BT_IRQ          10
  32
  33 #define BT_CR0          0x0
  34 #define   BT_CR0_IO_BASE                16
  35 #define   BT_CR0_IRQ                    12
  36 #define   BT_CR0_EN_CLR_SLV_RDP         0x8
  37 #define   BT_CR0_EN_CLR_SLV_WRP         0x4
  38 #define   BT_CR0_ENABLE_IBT             0x1
  39 #define BT_CR1          0x4
  40 #define   BT_CR1_IRQ_H2B        0x01
  41 #define   BT_CR1_IRQ_HBUSY      0x40
  42 #define BT_CR2          0x8
  43 #define   BT_CR2_IRQ_H2B        0x01
  44 #define   BT_CR2_IRQ_HBUSY      0x40
  45 #define BT_CR3          0xc
  46 #define BT_CTRL         0x10
  47 #define   BT_CTRL_B_BUSY                0x80
  48 #define   BT_CTRL_H_BUSY                0x40
  49 #define   BT_CTRL_OEM0                  0x20
  50 #define   BT_CTRL_SMS_ATN               0x10
  51 #define   BT_CTRL_B2H_ATN               0x08
  52 #define   BT_CTRL_H2B_ATN               0x04
  53 #define   BT_CTRL_CLR_RD_PTR            0x02
  54 #define   BT_CTRL_CLR_WR_PTR            0x01
  55 #define BT_BMC2HOST     0x14
  56 #define BT_INTMASK      0x18
  57 #define   BT_INTMASK_B2H_IRQEN          0x01
  58 #define   BT_INTMASK_B2H_IRQ            0x02
  59 #define   BT_INTMASK_BMC_HWRST          0x80
  60
  61 #define BT_BMC_BUFFER_SIZE 256
  62
  63 struct bt_bmc {
  64         struct device           dev;
  65         struct miscdevice       miscdev;
  66         struct regmap           *map;
  67         int                     offset;
  68         int                     irq;
  69         wait_queue_head_t       queue;
  70         struct timer_list       poll_timer;
  71         struct mutex            mutex;
  72 };
  73
  74 static atomic_t open_count = ATOMIC_INIT(0);
  75
  76 static const struct regmap_config bt_regmap_cfg = {
  77         .reg_bits = 32,
  78         .val_bits = 32,
  79         .reg_stride = 4,
  80 };
  81
  82 static u8 bt_inb(struct bt_bmc *bt_bmc, int reg)
  83 {
  84         uint32_t val = 0;
  85         int rc;
  86
  87         rc = regmap_read(bt_bmc->map, bt_bmc->offset + reg, &val);
  88         WARN(rc != 0, "regmap_read() failed: %d\n", rc);
  89
  90         return rc == 0 ? (u8) val : 0;
  91 }
  92
  93 static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
  94 {
  95         int rc;
  96
  97         rc = regmap_write(bt_bmc->map, bt_bmc->offset + reg, data);
  98         WARN(rc != 0, "regmap_write() failed: %d\n", rc);
  99 }
 100
 101 static void clr_rd_ptr(struct bt_bmc *bt_bmc)
 102 {
 103         bt_outb(bt_bmc, BT_CTRL_CLR_RD_PTR, BT_CTRL);
 104 }
 105
 106 static void clr_wr_ptr(struct bt_bmc *bt_bmc)
 107 {
 108         bt_outb(bt_bmc, BT_CTRL_CLR_WR_PTR, BT_CTRL);
 109 }
 110
 111 static void clr_h2b_atn(struct bt_bmc *bt_bmc)
 112 {
 113         bt_outb(bt_bmc, BT_CTRL_H2B_ATN, BT_CTRL);
 114 }
 115
 116 static void set_b_busy(struct bt_bmc *bt_bmc)
 117 {
 118         if (!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY))
 119                 bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
 120 }
 121
 122 static void clr_b_busy(struct bt_bmc *bt_bmc)
 123 {
 124         if (bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY)
 125                 bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
 126 }
 127
 128 static void set_b2h_atn(struct bt_bmc *bt_bmc)
 129 {
 130         bt_outb(bt_bmc, BT_CTRL_B2H_ATN, BT_CTRL);
 131 }
 132
 133 static u8 bt_read(struct bt_bmc *bt_bmc)
 134 {
 135         return bt_inb(bt_bmc, BT_BMC2HOST);
 136 }
 137
 138 static ssize_t bt_readn(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
 139 {
 140         int i;
 141
 142         for (i = 0; i < n; i++)
 143                 buf[i] = bt_read(bt_bmc);
 144         return n;
 145 }
 146
 147 static void bt_write(struct bt_bmc *bt_bmc, u8 c)
 148 {
 149         bt_outb(bt_bmc, c, BT_BMC2HOST);
 150 }
 151
 152 static ssize_t bt_writen(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
 153 {
 154         int i;
 155
 156         for (i = 0; i < n; i++)
 157                 bt_write(bt_bmc, buf[i]);
 158         return n;
 159 }
 160
 161 static void set_sms_atn(struct bt_bmc *bt_bmc)
 162 {
 163         bt_outb(bt_bmc, BT_CTRL_SMS_ATN, BT_CTRL);
 164 }
 165
 166 static struct bt_bmc *file_bt_bmc(struct file *file)
 167 {
 168         return container_of(file->private_data, struct bt_bmc, miscdev);
 169 }
 170
 171 static int bt_bmc_open(struct inode *inode, struct file *file)
 172 {
 173         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 174
 175         if (atomic_inc_return(&open_count) == 1) {
 176                 clr_b_busy(bt_bmc);
 177                 return 0;
 178         }
 179
 180         atomic_dec(&open_count);
 181         return -EBUSY;
 182 }
 183
 184 /*
 185  * The BT (Block Transfer) interface means that entire messages are
 186  * buffered by the host before a notification is sent to the BMC that
 187  * there is data to be read. The first byte is the length and the
 188  * message data follows. The read operation just tries to capture the
 189  * whole before returning it to userspace.
 190  *
 191  * BT Message format :
 192  *
 193  *    Byte 1  Byte 2     Byte 3  Byte 4  Byte 5:N
 194  *    Length  NetFn/LUN  Seq     Cmd     Data
 195  *
 196  */
 197 static ssize_t bt_bmc_read(struct file *file, char __user *buf,
 198                            size_t count, loff_t *ppos)
 199 {
 200         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 201         u8 len;
 202         int len_byte = 1;
 203         u8 kbuffer[BT_BMC_BUFFER_SIZE];
 204         ssize_t ret = 0;
 205         ssize_t nread;
 206
 207         WARN_ON(*ppos);
 208
 209         if (wait_event_interruptible(bt_bmc->queue,
 210                                      bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))
 211                 return -ERESTARTSYS;
 212
 213         mutex_lock(&bt_bmc->mutex);
 214
 215         if (unlikely(!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))) {
 216                 ret = -EIO;
 217                 goto out_unlock;
 218         }
 219
 220         set_b_busy(bt_bmc);
 221         clr_h2b_atn(bt_bmc);
 222         clr_rd_ptr(bt_bmc);
 223
 224         /*
 225          * The BT frames start with the message length, which does not
 226          * include the length byte.
 227          */
 228         kbuffer[0] = bt_read(bt_bmc);
 229         len = kbuffer[0];
 230
 231         /* We pass the length back to userspace as well */
 232         if (len + 1 > count)
 233                 len = count - 1;
 234
 235         while (len) {
 236                 nread = min_t(ssize_t, len, sizeof(kbuffer) - len_byte);
 237
 238                 bt_readn(bt_bmc, kbuffer + len_byte, nread);
 239
 240                 if (copy_to_user(buf, kbuffer, nread + len_byte)) {
 241                         ret = -EFAULT;
 242                         break;
 243                 }
 244                 len -= nread;
 245                 buf += nread + len_byte;
 246                 ret += nread + len_byte;
 247                 len_byte = 0;
 248         }
 249
 250         clr_b_busy(bt_bmc);
 251
 252 out_unlock:
 253         mutex_unlock(&bt_bmc->mutex);
 254         return ret;
 255 }
 256
 257 /*
 258  * BT Message response format :
 259  *
 260  *    Byte 1  Byte 2     Byte 3  Byte 4  Byte 5  Byte 6:N
 261  *    Length  NetFn/LUN  Seq     Cmd     Code    Data
 262  */
 263 static ssize_t bt_bmc_write(struct file *file, const char __user *buf,
 264                             size_t count, loff_t *ppos)
 265 {
 266         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 267         u8 kbuffer[BT_BMC_BUFFER_SIZE];
 268         ssize_t ret = 0;
 269         ssize_t nwritten;
 270
 271         /*
 272          * send a minimum response size
 273          */
 274         if (count < 5)
 275                 return -EINVAL;
 276
 277         WARN_ON(*ppos);
 278
 279         /*
 280          * There's no interrupt for clearing bmc busy so we have to
 281          * poll
 282          */
 283         if (wait_event_interruptible(bt_bmc->queue,
 284                                      !(bt_inb(bt_bmc, BT_CTRL) &
 285                                        (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))))
 286                 return -ERESTARTSYS;
 287
 288         mutex_lock(&bt_bmc->mutex);
 289
 290         if (unlikely(bt_inb(bt_bmc, BT_CTRL) &
 291                      (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))) {
 292                 ret = -EIO;
 293                 goto out_unlock;
 294         }
 295
 296         clr_wr_ptr(bt_bmc);
 297
 298         while (count) {
 299                 nwritten = min_t(ssize_t, count, sizeof(kbuffer));
 300                 if (copy_from_user(&kbuffer, buf, nwritten)) {
 301                         ret = -EFAULT;
 302                         break;
 303                 }
 304
 305                 bt_writen(bt_bmc, kbuffer, nwritten);
 306
 307                 count -= nwritten;
 308                 buf += nwritten;
 309                 ret += nwritten;
 310         }
 311
 312         set_b2h_atn(bt_bmc);
 313
 314 out_unlock:
 315         mutex_unlock(&bt_bmc->mutex);
 316         return ret;
 317 }
 318
 319 static long bt_bmc_ioctl(struct file *file, unsigned int cmd,
 320                          unsigned long param)
 321 {
 322         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 323
 324         switch (cmd) {
 325         case BT_BMC_IOCTL_SMS_ATN:
 326                 set_sms_atn(bt_bmc);
 327                 return 0;
 328         }
 329         return -EINVAL;
 330 }
 331
 332 static int bt_bmc_release(struct inode *inode, struct file *file)
 333 {
 334         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 335
 336         atomic_dec(&open_count);
 337         set_b_busy(bt_bmc);
 338         return 0;
 339 }
 340
 341 static unsigned int bt_bmc_poll(struct file *file, poll_table *wait)
 342 {
 343         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 344         unsigned int mask = 0;
 345         u8 ctrl;
 346
 347         poll_wait(file, &bt_bmc->queue, wait);
 348
 349         ctrl = bt_inb(bt_bmc, BT_CTRL);
 350
 351         if (ctrl & BT_CTRL_H2B_ATN)
 352                 mask |= POLLIN;
 353
 354         if (!(ctrl & (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN)))
 355                 mask |= POLLOUT;
 356
 357         return mask;
 358 }
 359
 360 static const struct file_operations bt_bmc_fops = {
 361         .owner          = THIS_MODULE,
 362         .open           = bt_bmc_open,
 363         .read           = bt_bmc_read,
 364         .write          = bt_bmc_write,
 365         .release        = bt_bmc_release,
 366         .poll           = bt_bmc_poll,
 367         .unlocked_ioctl = bt_bmc_ioctl,
 368 };
 369
 370 static void poll_timer(struct timer_list *t)
 371 {
 372         struct bt_bmc *bt_bmc = from_timer(bt_bmc, t, poll_timer);
 373
 374         bt_bmc->poll_timer.expires += msecs_to_jiffies(500);
 375         wake_up(&bt_bmc->queue);
 376         add_timer(&bt_bmc->poll_timer);
 377 }
 378
 379 static irqreturn_t bt_bmc_irq(int irq, void *arg)
 380 {
 381         struct bt_bmc *bt_bmc = arg;
 382         u32 reg;
 383         int rc;
 384
 385         rc = regmap_read(bt_bmc->map, bt_bmc->offset + BT_CR2, &reg);
 386         if (rc)
 387                 return IRQ_NONE;
 388
 389         reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
 390         if (!reg)
 391                 return IRQ_NONE;
 392
 393         /* ack pending IRQs */
 394         regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR2, reg);
 395
 396         wake_up(&bt_bmc->queue);
 397         return IRQ_HANDLED;
 398 }
 399
 400 static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 401                              struct platform_device *pdev)
 402 {
 403         struct device *dev = &pdev->dev;
 404         int rc;
 405
 406         bt_bmc->irq = platform_get_irq(pdev, 0);
 407         if (!bt_bmc->irq)
 408                 return -ENODEV;
 409
 410         rc = devm_request_irq(dev, bt_bmc->irq, bt_bmc_irq, IRQF_SHARED,
 411                               DEVICE_NAME, bt_bmc);
 412         if (rc < 0) {
 413                 dev_warn(dev, "Unable to request IRQ %d\n", bt_bmc->irq);
 414                 bt_bmc->irq = 0;
 415                 return rc;
 416         }
 417
 418         /*
 419          * Configure IRQs on the bmc clearing the H2B and HBUSY bits;
 420          * H2B will be asserted when the bmc has data for us; HBUSY
 421          * will be cleared (along with B2H) when we can write the next
 422          * message to the BT buffer
 423          */
 424         rc = regmap_update_bits(bt_bmc->map, bt_bmc->offset + BT_CR1,
 425                                 (BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY),
 426                                 (BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY));
 427
 428         return rc;
 429 }
 430
 431 static int bt_bmc_probe(struct platform_device *pdev)
 432 {
 433         struct bt_bmc *bt_bmc;
 434         struct device *dev;
 435         int rc;
 436
 437         if (!pdev || !pdev->dev.of_node)
 438                 return -ENODEV;
 439
 440         dev = &pdev->dev;
 441         dev_info(dev, "Found bt bmc device\n");
 442
 443         bt_bmc = devm_kzalloc(dev, sizeof(*bt_bmc), GFP_KERNEL);
 444         if (!bt_bmc)
 445                 return -ENOMEM;
 446
 447         dev_set_drvdata(&pdev->dev, bt_bmc);
 448
 449         bt_bmc->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
 450         if (IS_ERR(bt_bmc->map)) {
 451                 struct resource *res;
 452                 void __iomem *base;
 453
 454                 /*
 455                  * Assume it's not the MFD-based devicetree description, in
 456                  * which case generate a regmap ourselves
 457                  */
 458                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 459                 base = devm_ioremap_resource(&pdev->dev, res);
 460                 if (IS_ERR(base))
 461                         return PTR_ERR(base);
 462
 463                 bt_bmc->map = devm_regmap_init_mmio(dev, base, &bt_regmap_cfg);
 464                 bt_bmc->offset = 0;
 465         } else {
 466                 rc = of_property_read_u32(dev->of_node, "reg", &bt_bmc->offset);
 467                 if (rc)
 468                         return rc;
 469         }
 470
 471         mutex_init(&bt_bmc->mutex);
 472         init_waitqueue_head(&bt_bmc->queue);
 473
 474         bt_bmc->miscdev.minor   = MISC_DYNAMIC_MINOR,
 475                 bt_bmc->miscdev.name    = DEVICE_NAME,
 476                 bt_bmc->miscdev.fops    = &bt_bmc_fops,
 477                 bt_bmc->miscdev.parent = dev;
 478         rc = misc_register(&bt_bmc->miscdev);
 479         if (rc) {
 480                 dev_err(dev, "Unable to register misc device\n");
 481                 return rc;
 482         }
 483
 484         bt_bmc_config_irq(bt_bmc, pdev);
 485
 486         if (bt_bmc->irq) {
 487                 dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
 488         } else {
 489                 dev_info(dev, "No IRQ; using timer\n");
 490                 timer_setup(&bt_bmc->poll_timer, poll_timer, 0);
 491                 bt_bmc->poll_timer.expires = jiffies + msecs_to_jiffies(10);
 492                 add_timer(&bt_bmc->poll_timer);
 493         }
 494
 495         regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR0,
 496                      (BT_IO_BASE << BT_CR0_IO_BASE) |
 497                      (BT_IRQ << BT_CR0_IRQ) |
 498                      BT_CR0_EN_CLR_SLV_RDP |
 499                      BT_CR0_EN_CLR_SLV_WRP |
 500                      BT_CR0_ENABLE_IBT);
 501
 502         clr_b_busy(bt_bmc);
 503
 504         return 0;
 505 }
 506
 507 static int bt_bmc_remove(struct platform_device *pdev)
 508 {
 509         struct bt_bmc *bt_bmc = dev_get_drvdata(&pdev->dev);
 510
 511         misc_deregister(&bt_bmc->miscdev);
 512         if (!bt_bmc->irq)
 513                 del_timer_sync(&bt_bmc->poll_timer);
 514         return 0;
 515 }
 516
 517 static const struct of_device_id bt_bmc_match[] = {
 518         { .compatible = "aspeed,ast2400-ibt-bmc" },
 519         { .compatible = "aspeed,ast2500-ibt-bmc" },
 520         { },
 521 };
 522
 523 static struct platform_driver bt_bmc_driver = {
 524         .driver = {
 525                 .name           = DEVICE_NAME,
 526                 .of_match_table = bt_bmc_match,
 527         },
 528         .probe = bt_bmc_probe,
 529         .remove = bt_bmc_remove,
 530 };
 531
 532 module_platform_driver(bt_bmc_driver);
 533
 534 MODULE_DEVICE_TABLE(of, bt_bmc_match);
 535 MODULE_LICENSE("GPL");
 536 MODULE_AUTHOR("Alistair Popple <alistair@popple.id.au>");
 537 MODULE_DESCRIPTION("Linux device interface to the IPMI BT interface");