drivers/char/ipmi/bt-bmc.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (c) 2015-2016, IBM Corporation.
   4  */
   5
   6 #include <linux/atomic.h>
   7 #include <linux/bt-bmc.h>
   8 #include <linux/errno.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/io.h>
  11 #include <linux/miscdevice.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/poll.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18
  19 /*
  20  * This is a BMC device used to communicate to the host
  21  */
  22 #define DEVICE_NAME     "ipmi-bt-host"
  23
  24 #define BT_IO_BASE      0xe4
  25 #define BT_IRQ          10
  26
  27 #define BT_CR0          0x0
  28 #define   BT_CR0_IO_BASE                16
  29 #define   BT_CR0_IRQ                    12
  30 #define   BT_CR0_EN_CLR_SLV_RDP         0x8
  31 #define   BT_CR0_EN_CLR_SLV_WRP         0x4
  32 #define   BT_CR0_ENABLE_IBT             0x1
  33 #define BT_CR1          0x4
  34 #define   BT_CR1_IRQ_H2B        0x01
  35 #define   BT_CR1_IRQ_HBUSY      0x40
  36 #define BT_CR2          0x8
  37 #define   BT_CR2_IRQ_H2B        0x01
  38 #define   BT_CR2_IRQ_HBUSY      0x40
  39 #define BT_CR3          0xc
  40 #define BT_CTRL         0x10
  41 #define   BT_CTRL_B_BUSY                0x80
  42 #define   BT_CTRL_H_BUSY                0x40
  43 #define   BT_CTRL_OEM0                  0x20
  44 #define   BT_CTRL_SMS_ATN               0x10
  45 #define   BT_CTRL_B2H_ATN               0x08
  46 #define   BT_CTRL_H2B_ATN               0x04
  47 #define   BT_CTRL_CLR_RD_PTR            0x02
  48 #define   BT_CTRL_CLR_WR_PTR            0x01
  49 #define BT_BMC2HOST     0x14
  50 #define BT_INTMASK      0x18
  51 #define   BT_INTMASK_B2H_IRQEN          0x01
  52 #define   BT_INTMASK_B2H_IRQ            0x02
  53 #define   BT_INTMASK_BMC_HWRST          0x80
  54
  55 #define BT_BMC_BUFFER_SIZE 256
  56
  57 struct bt_bmc {
  58         struct device           dev;
  59         struct miscdevice       miscdev;
  60         void __iomem            *base;
  61         int                     irq;
  62         wait_queue_head_t       queue;
  63         struct timer_list       poll_timer;
  64         struct mutex            mutex;
  65 };
  66
  67 static atomic_t open_count = ATOMIC_INIT(0);
  68
  69 static u8 bt_inb(struct bt_bmc *bt_bmc, int reg)
  70 {
  71         return readb(bt_bmc->base + reg);
  72 }
  73
  74 static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
  75 {
  76         writeb(data, bt_bmc->base + reg);
  77 }
  78
  79 static void clr_rd_ptr(struct bt_bmc *bt_bmc)
  80 {
  81         bt_outb(bt_bmc, BT_CTRL_CLR_RD_PTR, BT_CTRL);
  82 }
  83
  84 static void clr_wr_ptr(struct bt_bmc *bt_bmc)
  85 {
  86         bt_outb(bt_bmc, BT_CTRL_CLR_WR_PTR, BT_CTRL);
  87 }
  88
  89 static void clr_h2b_atn(struct bt_bmc *bt_bmc)
  90 {
  91         bt_outb(bt_bmc, BT_CTRL_H2B_ATN, BT_CTRL);
  92 }
  93
  94 static void set_b_busy(struct bt_bmc *bt_bmc)
  95 {
  96         if (!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY))
  97                 bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
  98 }
  99
 100 static void clr_b_busy(struct bt_bmc *bt_bmc)
 101 {
 102         if (bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY)
 103                 bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
 104 }
 105
 106 static void set_b2h_atn(struct bt_bmc *bt_bmc)
 107 {
 108         bt_outb(bt_bmc, BT_CTRL_B2H_ATN, BT_CTRL);
 109 }
 110
 111 static u8 bt_read(struct bt_bmc *bt_bmc)
 112 {
 113         return bt_inb(bt_bmc, BT_BMC2HOST);
 114 }
 115
 116 static ssize_t bt_readn(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
 117 {
 118         int i;
 119
 120         for (i = 0; i < n; i++)
 121                 buf[i] = bt_read(bt_bmc);
 122         return n;
 123 }
 124
 125 static void bt_write(struct bt_bmc *bt_bmc, u8 c)
 126 {
 127         bt_outb(bt_bmc, c, BT_BMC2HOST);
 128 }
 129
 130 static ssize_t bt_writen(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
 131 {
 132         int i;
 133
 134         for (i = 0; i < n; i++)
 135                 bt_write(bt_bmc, buf[i]);
 136         return n;
 137 }
 138
 139 static void set_sms_atn(struct bt_bmc *bt_bmc)
 140 {
 141         bt_outb(bt_bmc, BT_CTRL_SMS_ATN, BT_CTRL);
 142 }
 143
 144 static struct bt_bmc *file_bt_bmc(struct file *file)
 145 {
 146         return container_of(file->private_data, struct bt_bmc, miscdev);
 147 }
 148
 149 static int bt_bmc_open(struct inode *inode, struct file *file)
 150 {
 151         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 152
 153         if (atomic_inc_return(&open_count) == 1) {
 154                 clr_b_busy(bt_bmc);
 155                 return 0;
 156         }
 157
 158         atomic_dec(&open_count);
 159         return -EBUSY;
 160 }
 161
 162 /*
 163  * The BT (Block Transfer) interface means that entire messages are
 164  * buffered by the host before a notification is sent to the BMC that
 165  * there is data to be read. The first byte is the length and the
 166  * message data follows. The read operation just tries to capture the
 167  * whole before returning it to userspace.
 168  *
 169  * BT Message format :
 170  *
 171  *    Byte 1  Byte 2     Byte 3  Byte 4  Byte 5:N
 172  *    Length  NetFn/LUN  Seq     Cmd     Data
 173  *
 174  */
 175 static ssize_t bt_bmc_read(struct file *file, char __user *buf,
 176                            size_t count, loff_t *ppos)
 177 {
 178         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 179         u8 len;
 180         int len_byte = 1;
 181         u8 kbuffer[BT_BMC_BUFFER_SIZE];
 182         ssize_t ret = 0;
 183         ssize_t nread;
 184
 185         WARN_ON(*ppos);
 186
 187         if (wait_event_interruptible(bt_bmc->queue,
 188                                      bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))
 189                 return -ERESTARTSYS;
 190
 191         mutex_lock(&bt_bmc->mutex);
 192
 193         if (unlikely(!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))) {
 194                 ret = -EIO;
 195                 goto out_unlock;
 196         }
 197
 198         set_b_busy(bt_bmc);
 199         clr_h2b_atn(bt_bmc);
 200         clr_rd_ptr(bt_bmc);
 201
 202         /*
 203          * The BT frames start with the message length, which does not
 204          * include the length byte.
 205          */
 206         kbuffer[0] = bt_read(bt_bmc);
 207         len = kbuffer[0];
 208
 209         /* We pass the length back to userspace as well */
 210         if (len + 1 > count)
 211                 len = count - 1;
 212
 213         while (len) {
 214                 nread = min_t(ssize_t, len, sizeof(kbuffer) - len_byte);
 215
 216                 bt_readn(bt_bmc, kbuffer + len_byte, nread);
 217
 218                 if (copy_to_user(buf, kbuffer, nread + len_byte)) {
 219                         ret = -EFAULT;
 220                         break;
 221                 }
 222                 len -= nread;
 223                 buf += nread + len_byte;
 224                 ret += nread + len_byte;
 225                 len_byte = 0;
 226         }
 227
 228         clr_b_busy(bt_bmc);
 229
 230 out_unlock:
 231         mutex_unlock(&bt_bmc->mutex);
 232         return ret;
 233 }
 234
 235 /*
 236  * BT Message response format :
 237  *
 238  *    Byte 1  Byte 2     Byte 3  Byte 4  Byte 5  Byte 6:N
 239  *    Length  NetFn/LUN  Seq     Cmd     Code    Data
 240  */
 241 static ssize_t bt_bmc_write(struct file *file, const char __user *buf,
 242                             size_t count, loff_t *ppos)
 243 {
 244         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 245         u8 kbuffer[BT_BMC_BUFFER_SIZE];
 246         ssize_t ret = 0;
 247         ssize_t nwritten;
 248
 249         /*
 250          * send a minimum response size
 251          */
 252         if (count < 5)
 253                 return -EINVAL;
 254
 255         WARN_ON(*ppos);
 256
 257         /*
 258          * There's no interrupt for clearing bmc busy so we have to
 259          * poll
 260          */
 261         if (wait_event_interruptible(bt_bmc->queue,
 262                                      !(bt_inb(bt_bmc, BT_CTRL) &
 263                                        (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))))
 264                 return -ERESTARTSYS;
 265
 266         mutex_lock(&bt_bmc->mutex);
 267
 268         if (unlikely(bt_inb(bt_bmc, BT_CTRL) &
 269                      (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))) {
 270                 ret = -EIO;
 271                 goto out_unlock;
 272         }
 273
 274         clr_wr_ptr(bt_bmc);
 275
 276         while (count) {
 277                 nwritten = min_t(ssize_t, count, sizeof(kbuffer));
 278                 if (copy_from_user(&kbuffer, buf, nwritten)) {
 279                         ret = -EFAULT;
 280                         break;
 281                 }
 282
 283                 bt_writen(bt_bmc, kbuffer, nwritten);
 284
 285                 count -= nwritten;
 286                 buf += nwritten;
 287                 ret += nwritten;
 288         }
 289
 290         set_b2h_atn(bt_bmc);
 291
 292 out_unlock:
 293         mutex_unlock(&bt_bmc->mutex);
 294         return ret;
 295 }
 296
 297 static long bt_bmc_ioctl(struct file *file, unsigned int cmd,
 298                          unsigned long param)
 299 {
 300         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 301
 302         switch (cmd) {
 303         case BT_BMC_IOCTL_SMS_ATN:
 304                 set_sms_atn(bt_bmc);
 305                 return 0;
 306         }
 307         return -EINVAL;
 308 }
 309
 310 static int bt_bmc_release(struct inode *inode, struct file *file)
 311 {
 312         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 313
 314         atomic_dec(&open_count);
 315         set_b_busy(bt_bmc);
 316         return 0;
 317 }
 318
 319 static __poll_t bt_bmc_poll(struct file *file, poll_table *wait)
 320 {
 321         struct bt_bmc *bt_bmc = file_bt_bmc(file);
 322         __poll_t mask = 0;
 323         u8 ctrl;
 324
 325         poll_wait(file, &bt_bmc->queue, wait);
 326
 327         ctrl = bt_inb(bt_bmc, BT_CTRL);
 328
 329         if (ctrl & BT_CTRL_H2B_ATN)
 330                 mask |= EPOLLIN;
 331
 332         if (!(ctrl & (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN)))
 333                 mask |= EPOLLOUT;
 334
 335         return mask;
 336 }
 337
 338 static const struct file_operations bt_bmc_fops = {
 339         .owner          = THIS_MODULE,
 340         .open           = bt_bmc_open,
 341         .read           = bt_bmc_read,
 342         .write          = bt_bmc_write,
 343         .release        = bt_bmc_release,
 344         .poll           = bt_bmc_poll,
 345         .unlocked_ioctl = bt_bmc_ioctl,
 346 };
 347
 348 static void poll_timer(struct timer_list *t)
 349 {
 350         struct bt_bmc *bt_bmc = from_timer(bt_bmc, t, poll_timer);
 351
 352         bt_bmc->poll_timer.expires += msecs_to_jiffies(500);
 353         wake_up(&bt_bmc->queue);
 354         add_timer(&bt_bmc->poll_timer);
 355 }
 356
 357 static irqreturn_t bt_bmc_irq(int irq, void *arg)
 358 {
 359         struct bt_bmc *bt_bmc = arg;
 360         u32 reg;
 361
 362         reg = readl(bt_bmc->base + BT_CR2);
 363
 364         reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
 365         if (!reg)
 366                 return IRQ_NONE;
 367
 368         /* ack pending IRQs */
 369         writel(reg, bt_bmc->base + BT_CR2);
 370
 371         wake_up(&bt_bmc->queue);
 372         return IRQ_HANDLED;
 373 }
 374
 375 static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 376                              struct platform_device *pdev)
 377 {
 378         struct device *dev = &pdev->dev;
 379         int rc;
 380         u32 reg;
 381
 382         bt_bmc->irq = platform_get_irq_optional(pdev, 0);
 383         if (bt_bmc->irq < 0)
 384                 return bt_bmc->irq;
 385
 386         rc = devm_request_irq(dev, bt_bmc->irq, bt_bmc_irq, IRQF_SHARED,
 387                               DEVICE_NAME, bt_bmc);
 388         if (rc < 0) {
 389                 dev_warn(dev, "Unable to request IRQ %d\n", bt_bmc->irq);
 390                 bt_bmc->irq = rc;
 391                 return rc;
 392         }
 393
 394         /*
 395          * Configure IRQs on the bmc clearing the H2B and HBUSY bits;
 396          * H2B will be asserted when the bmc has data for us; HBUSY
 397          * will be cleared (along with B2H) when we can write the next
 398          * message to the BT buffer
 399          */
 400         reg = readl(bt_bmc->base + BT_CR1);
 401         reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
 402         writel(reg, bt_bmc->base + BT_CR1);
 403
 404         return 0;
 405 }
 406
 407 static int bt_bmc_probe(struct platform_device *pdev)
 408 {
 409         struct bt_bmc *bt_bmc;
 410         struct device *dev;
 411         int rc;
 412
 413         dev = &pdev->dev;
 414         dev_info(dev, "Found bt bmc device\n");
 415
 416         bt_bmc = devm_kzalloc(dev, sizeof(*bt_bmc), GFP_KERNEL);
 417         if (!bt_bmc)
 418                 return -ENOMEM;
 419
 420         dev_set_drvdata(&pdev->dev, bt_bmc);
 421
 422         bt_bmc->base = devm_platform_ioremap_resource(pdev, 0);
 423         if (IS_ERR(bt_bmc->base))
 424                 return PTR_ERR(bt_bmc->base);
 425
 426         mutex_init(&bt_bmc->mutex);
 427         init_waitqueue_head(&bt_bmc->queue);
 428
 429         bt_bmc->miscdev.minor   = MISC_DYNAMIC_MINOR;
 430         bt_bmc->miscdev.name    = DEVICE_NAME;
 431         bt_bmc->miscdev.fops    = &bt_bmc_fops;
 432         bt_bmc->miscdev.parent = dev;
 433         rc = misc_register(&bt_bmc->miscdev);
 434         if (rc) {
 435                 dev_err(dev, "Unable to register misc device\n");
 436                 return rc;
 437         }
 438
 439         bt_bmc_config_irq(bt_bmc, pdev);
 440
 441         if (bt_bmc->irq >= 0) {
 442                 dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
 443         } else {
 444                 dev_info(dev, "No IRQ; using timer\n");
 445                 timer_setup(&bt_bmc->poll_timer, poll_timer, 0);
 446                 bt_bmc->poll_timer.expires = jiffies + msecs_to_jiffies(10);
 447                 add_timer(&bt_bmc->poll_timer);
 448         }
 449
 450         writel((BT_IO_BASE << BT_CR0_IO_BASE) |
 451                      (BT_IRQ << BT_CR0_IRQ) |
 452                      BT_CR0_EN_CLR_SLV_RDP |
 453                      BT_CR0_EN_CLR_SLV_WRP |
 454                      BT_CR0_ENABLE_IBT,
 455                 bt_bmc->base + BT_CR0);
 456
 457         clr_b_busy(bt_bmc);
 458
 459         return 0;
 460 }
 461
 462 static void bt_bmc_remove(struct platform_device *pdev)
 463 {
 464         struct bt_bmc *bt_bmc = dev_get_drvdata(&pdev->dev);
 465
 466         misc_deregister(&bt_bmc->miscdev);
 467         if (bt_bmc->irq < 0)
 468                 del_timer_sync(&bt_bmc->poll_timer);
 469 }
 470
 471 static const struct of_device_id bt_bmc_match[] = {
 472         { .compatible = "aspeed,ast2400-ibt-bmc" },
 473         { .compatible = "aspeed,ast2500-ibt-bmc" },
 474         { .compatible = "aspeed,ast2600-ibt-bmc" },
 475         { },
 476 };
 477
 478 static struct platform_driver bt_bmc_driver = {
 479         .driver = {
 480                 .name           = DEVICE_NAME,
 481                 .of_match_table = bt_bmc_match,
 482         },
 483         .probe = bt_bmc_probe,
 484         .remove_new = bt_bmc_remove,
 485 };
 486
 487 module_platform_driver(bt_bmc_driver);
 488
 489 MODULE_DEVICE_TABLE(of, bt_bmc_match);
 490 MODULE_LICENSE("GPL");
 491 MODULE_AUTHOR("Alistair Popple <alistair@popple.id.au>");
 492 MODULE_DESCRIPTION("Linux device interface to the IPMI BT interface");