821 lines · c
1// SPDX-License-Identifier: GPL-2.02/* ePAPR hypervisor byte channel device driver3 *4 * Copyright 2009-2011 Freescale Semiconductor, Inc.5 *6 * Author: Timur Tabi <timur@freescale.com>7 *8 * This driver support three distinct interfaces, all of which are related to9 * ePAPR hypervisor byte channels.10 *11 * 1) An early-console (udbg) driver. This provides early console output12 * through a byte channel. The byte channel handle must be specified in a13 * Kconfig option.14 *15 * 2) A normal console driver. Output is sent to the byte channel designated16 * for stdout in the device tree. The console driver is for handling kernel17 * printk calls.18 *19 * 3) A tty driver, which is used to handle user-space input and output. The20 * byte channel used for the console is designated as the default tty.21 */22 23#include <linux/init.h>24#include <linux/slab.h>25#include <linux/err.h>26#include <linux/interrupt.h>27#include <linux/fs.h>28#include <linux/poll.h>29#include <asm/epapr_hcalls.h>30#include <linux/of.h>31#include <linux/of_irq.h>32#include <linux/platform_device.h>33#include <linux/cdev.h>34#include <linux/console.h>35#include <linux/tty.h>36#include <linux/tty_flip.h>37#include <linux/circ_buf.h>38#include <asm/udbg.h>39 40/* The size of the transmit circular buffer. This must be a power of two. */41#define BUF_SIZE 204842 43/* Per-byte channel private data */44struct ehv_bc_data {45 struct device *dev;46 struct tty_port port;47 uint32_t handle;48 unsigned int rx_irq;49 unsigned int tx_irq;50 51 spinlock_t lock; /* lock for transmit buffer */52 u8 buf[BUF_SIZE]; /* transmit circular buffer */53 unsigned int head; /* circular buffer head */54 unsigned int tail; /* circular buffer tail */55 56 int tx_irq_enabled; /* true == TX interrupt is enabled */57};58 59/* Array of byte channel objects */60static struct ehv_bc_data *bcs;61 62/* Byte channel handle for stdout (and stdin), taken from device tree */63static unsigned int stdout_bc;64 65/* Virtual IRQ for the byte channel handle for stdin, taken from device tree */66static unsigned int stdout_irq;67 68/**************************** SUPPORT FUNCTIONS ****************************/69 70/*71 * Enable the transmit interrupt72 *73 * Unlike a serial device, byte channels have no mechanism for disabling their74 * own receive or transmit interrupts. To emulate that feature, we toggle75 * the IRQ in the kernel.76 *77 * We cannot just blindly call enable_irq() or disable_irq(), because these78 * calls are reference counted. This means that we cannot call enable_irq()79 * if interrupts are already enabled. This can happen in two situations:80 *81 * 1. The tty layer makes two back-to-back calls to ehv_bc_tty_write()82 * 2. A transmit interrupt occurs while executing ehv_bc_tx_dequeue()83 *84 * To work around this, we keep a flag to tell us if the IRQ is enabled or not.85 */86static void enable_tx_interrupt(struct ehv_bc_data *bc)87{88 if (!bc->tx_irq_enabled) {89 enable_irq(bc->tx_irq);90 bc->tx_irq_enabled = 1;91 }92}93 94static void disable_tx_interrupt(struct ehv_bc_data *bc)95{96 if (bc->tx_irq_enabled) {97 disable_irq_nosync(bc->tx_irq);98 bc->tx_irq_enabled = 0;99 }100}101 102/*103 * find the byte channel handle to use for the console104 *105 * The byte channel to be used for the console is specified via a "stdout"106 * property in the /chosen node.107 */108static int find_console_handle(void)109{110 struct device_node *np = of_stdout;111 const uint32_t *iprop;112 113 /* We don't care what the aliased node is actually called. We only114 * care if it's compatible with "epapr,hv-byte-channel", because that115 * indicates that it's a byte channel node.116 */117 if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))118 return 0;119 120 stdout_irq = irq_of_parse_and_map(np, 0);121 if (!stdout_irq) {122 pr_err("ehv-bc: no 'interrupts' property in %pOF node\n", np);123 return 0;124 }125 126 /*127 * The 'hv-handle' property contains the handle for this byte channel.128 */129 iprop = of_get_property(np, "hv-handle", NULL);130 if (!iprop) {131 pr_err("ehv-bc: no 'hv-handle' property in %pOFn node\n",132 np);133 return 0;134 }135 stdout_bc = be32_to_cpu(*iprop);136 return 1;137}138 139static unsigned int local_ev_byte_channel_send(unsigned int handle,140 unsigned int *count,141 const u8 *p)142{143 u8 buffer[EV_BYTE_CHANNEL_MAX_BYTES];144 unsigned int c = *count;145 146 /*147 * ev_byte_channel_send() expects at least EV_BYTE_CHANNEL_MAX_BYTES148 * (16 B) in the buffer. Fake it using a local buffer if needed.149 */150 if (c < sizeof(buffer)) {151 memcpy_and_pad(buffer, sizeof(buffer), p, c, 0);152 p = buffer;153 }154 return ev_byte_channel_send(handle, count, p);155}156 157/*************************** EARLY CONSOLE DRIVER ***************************/158 159#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC160 161/*162 * send a byte to a byte channel, wait if necessary163 *164 * This function sends a byte to a byte channel, and it waits and165 * retries if the byte channel is full. It returns if the character166 * has been sent, or if some error has occurred.167 *168 */169static void byte_channel_spin_send(const u8 data)170{171 int ret, count;172 173 do {174 count = 1;175 ret = local_ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,176 &count, &data);177 } while (ret == EV_EAGAIN);178}179 180/*181 * The udbg subsystem calls this function to display a single character.182 * We convert CR to a CR/LF.183 */184static void ehv_bc_udbg_putc(char c)185{186 if (c == '\n')187 byte_channel_spin_send('\r');188 189 byte_channel_spin_send(c);190}191 192/*193 * early console initialization194 *195 * PowerPC kernels support an early printk console, also known as udbg.196 * This function must be called via the ppc_md.init_early function pointer.197 * At this point, the device tree has been unflattened, so we can obtain the198 * byte channel handle for stdout.199 *200 * We only support displaying of characters (putc). We do not support201 * keyboard input.202 */203void __init udbg_init_ehv_bc(void)204{205 unsigned int rx_count, tx_count;206 unsigned int ret;207 208 /* Verify the byte channel handle */209 ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,210 &rx_count, &tx_count);211 if (ret)212 return;213 214 udbg_putc = ehv_bc_udbg_putc;215 register_early_udbg_console();216 217 udbg_printf("ehv-bc: early console using byte channel handle %u\n",218 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);219}220 221#endif222 223/****************************** CONSOLE DRIVER ******************************/224 225static struct tty_driver *ehv_bc_driver;226 227/*228 * Byte channel console sending worker function.229 *230 * For consoles, if the output buffer is full, we should just spin until it231 * clears.232 */233static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,234 unsigned int count)235{236 unsigned int len;237 int ret = 0;238 239 while (count) {240 len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);241 do {242 ret = local_ev_byte_channel_send(handle, &len, s);243 } while (ret == EV_EAGAIN);244 count -= len;245 s += len;246 }247 248 return ret;249}250 251/*252 * write a string to the console253 *254 * This function gets called to write a string from the kernel, typically from255 * a printk(). This function spins until all data is written.256 *257 * We copy the data to a temporary buffer because we need to insert a \r in258 * front of every \n. It's more efficient to copy the data to the buffer than259 * it is to make multiple hcalls for each character or each newline.260 */261static void ehv_bc_console_write(struct console *co, const char *s,262 unsigned int count)263{264 char s2[EV_BYTE_CHANNEL_MAX_BYTES];265 unsigned int i, j = 0;266 char c;267 268 for (i = 0; i < count; i++) {269 c = *s++;270 271 if (c == '\n')272 s2[j++] = '\r';273 274 s2[j++] = c;275 if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {276 if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j))277 return;278 j = 0;279 }280 }281 282 if (j)283 ehv_bc_console_byte_channel_send(stdout_bc, s2, j);284}285 286/*287 * When /dev/console is opened, the kernel iterates the console list looking288 * for one with ->device and then calls that method. On success, it expects289 * the passed-in int* to contain the minor number to use.290 */291static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)292{293 *index = co->index;294 295 return ehv_bc_driver;296}297 298static struct console ehv_bc_console = {299 .name = "ttyEHV",300 .write = ehv_bc_console_write,301 .device = ehv_bc_console_device,302 .flags = CON_PRINTBUFFER | CON_ENABLED,303};304 305/*306 * Console initialization307 *308 * This is the first function that is called after the device tree is309 * available, so here is where we determine the byte channel handle and IRQ for310 * stdout/stdin, even though that information is used by the tty and character311 * drivers.312 */313static int __init ehv_bc_console_init(void)314{315 if (!find_console_handle()) {316 pr_debug("ehv-bc: stdout is not a byte channel\n");317 return -ENODEV;318 }319 320#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC321 /* Print a friendly warning if the user chose the wrong byte channel322 * handle for udbg.323 */324 if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)325 pr_warn("ehv-bc: udbg handle %u is not the stdout handle\n",326 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);327#endif328 329 /* add_preferred_console() must be called before register_console(),330 otherwise it won't work. However, we don't want to enumerate all the331 byte channels here, either, since we only care about one. */332 333 add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);334 register_console(&ehv_bc_console);335 336 pr_info("ehv-bc: registered console driver for byte channel %u\n",337 stdout_bc);338 339 return 0;340}341console_initcall(ehv_bc_console_init);342 343/******************************** TTY DRIVER ********************************/344 345/*346 * byte channel receive interrupt handler347 *348 * This ISR is called whenever data is available on a byte channel.349 */350static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)351{352 struct ehv_bc_data *bc = data;353 unsigned int rx_count, tx_count, len;354 int count;355 char buffer[EV_BYTE_CHANNEL_MAX_BYTES];356 int ret;357 358 /* Find out how much data needs to be read, and then ask the TTY layer359 * if it can handle that much. We want to ensure that every byte we360 * read from the byte channel will be accepted by the TTY layer.361 */362 ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);363 count = tty_buffer_request_room(&bc->port, rx_count);364 365 /* 'count' is the maximum amount of data the TTY layer can accept at366 * this time. However, during testing, I was never able to get 'count'367 * to be less than 'rx_count'. I'm not sure whether I'm calling it368 * correctly.369 */370 371 while (count > 0) {372 len = min_t(unsigned int, count, sizeof(buffer));373 374 /* Read some data from the byte channel. This function will375 * never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.376 */377 ev_byte_channel_receive(bc->handle, &len, buffer);378 379 /* 'len' is now the amount of data that's been received. 'len'380 * can't be zero, and most likely it's equal to one.381 */382 383 /* Pass the received data to the tty layer. */384 ret = tty_insert_flip_string(&bc->port, buffer, len);385 386 /* 'ret' is the number of bytes that the TTY layer accepted.387 * If it's not equal to 'len', then it means the buffer is388 * full, which should never happen. If it does happen, we can389 * exit gracefully, but we drop the last 'len - ret' characters390 * that we read from the byte channel.391 */392 if (ret != len)393 break;394 395 count -= len;396 }397 398 /* Tell the tty layer that we're done. */399 tty_flip_buffer_push(&bc->port);400 401 return IRQ_HANDLED;402}403 404/*405 * dequeue the transmit buffer to the hypervisor406 *407 * This function, which can be called in interrupt context, dequeues as much408 * data as possible from the transmit buffer to the byte channel.409 */410static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)411{412 unsigned int count;413 unsigned int len, ret;414 unsigned long flags;415 416 do {417 spin_lock_irqsave(&bc->lock, flags);418 len = min_t(unsigned int,419 CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),420 EV_BYTE_CHANNEL_MAX_BYTES);421 422 ret = local_ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);423 424 /* 'len' is valid only if the return code is 0 or EV_EAGAIN */425 if (!ret || (ret == EV_EAGAIN))426 bc->tail = (bc->tail + len) & (BUF_SIZE - 1);427 428 count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);429 spin_unlock_irqrestore(&bc->lock, flags);430 } while (count && !ret);431 432 spin_lock_irqsave(&bc->lock, flags);433 if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))434 /*435 * If we haven't emptied the buffer, then enable the TX IRQ.436 * We'll get an interrupt when there's more room in the437 * hypervisor's output buffer.438 */439 enable_tx_interrupt(bc);440 else441 disable_tx_interrupt(bc);442 spin_unlock_irqrestore(&bc->lock, flags);443}444 445/*446 * byte channel transmit interrupt handler447 *448 * This ISR is called whenever space becomes available for transmitting449 * characters on a byte channel.450 */451static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)452{453 struct ehv_bc_data *bc = data;454 455 ehv_bc_tx_dequeue(bc);456 tty_port_tty_wakeup(&bc->port);457 458 return IRQ_HANDLED;459}460 461/*462 * This function is called when the tty layer has data for us send. We store463 * the data first in a circular buffer, and then dequeue as much of that data464 * as possible.465 *466 * We don't need to worry about whether there is enough room in the buffer for467 * all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty468 * layer how much data it can safely send to us. We guarantee that469 * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us470 * too much data.471 */472static ssize_t ehv_bc_tty_write(struct tty_struct *ttys, const u8 *s,473 size_t count)474{475 struct ehv_bc_data *bc = ttys->driver_data;476 unsigned long flags;477 size_t len, written = 0;478 479 while (1) {480 spin_lock_irqsave(&bc->lock, flags);481 len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);482 if (count < len)483 len = count;484 if (len) {485 memcpy(bc->buf + bc->head, s, len);486 bc->head = (bc->head + len) & (BUF_SIZE - 1);487 }488 spin_unlock_irqrestore(&bc->lock, flags);489 if (!len)490 break;491 492 s += len;493 count -= len;494 written += len;495 }496 497 ehv_bc_tx_dequeue(bc);498 499 return written;500}501 502/*503 * This function can be called multiple times for a given tty_struct, which is504 * why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.505 *506 * The tty layer will still call this function even if the device was not507 * registered (i.e. tty_register_device() was not called). This happens508 * because tty_register_device() is optional and some legacy drivers don't509 * use it. So we need to check for that.510 */511static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)512{513 struct ehv_bc_data *bc = &bcs[ttys->index];514 515 if (!bc->dev)516 return -ENODEV;517 518 return tty_port_open(&bc->port, ttys, filp);519}520 521/*522 * Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will523 * still call this function to close the tty device. So we can't assume that524 * the tty port has been initialized.525 */526static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)527{528 struct ehv_bc_data *bc = &bcs[ttys->index];529 530 if (bc->dev)531 tty_port_close(&bc->port, ttys, filp);532}533 534/*535 * Return the amount of space in the output buffer536 *537 * This is actually a contract between the driver and the tty layer outlining538 * how much write room the driver can guarantee will be sent OR BUFFERED. This539 * driver MUST honor the return value.540 */541static unsigned int ehv_bc_tty_write_room(struct tty_struct *ttys)542{543 struct ehv_bc_data *bc = ttys->driver_data;544 unsigned long flags;545 unsigned int count;546 547 spin_lock_irqsave(&bc->lock, flags);548 count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);549 spin_unlock_irqrestore(&bc->lock, flags);550 551 return count;552}553 554/*555 * Stop sending data to the tty layer556 *557 * This function is called when the tty layer's input buffers are getting full,558 * so the driver should stop sending it data. The easiest way to do this is to559 * disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being560 * called.561 *562 * The hypervisor will continue to queue up any incoming data. If there is any563 * data in the queue when the RX interrupt is enabled, we'll immediately get an564 * RX interrupt.565 */566static void ehv_bc_tty_throttle(struct tty_struct *ttys)567{568 struct ehv_bc_data *bc = ttys->driver_data;569 570 disable_irq(bc->rx_irq);571}572 573/*574 * Resume sending data to the tty layer575 *576 * This function is called after previously calling ehv_bc_tty_throttle(). The577 * tty layer's input buffers now have more room, so the driver can resume578 * sending it data.579 */580static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)581{582 struct ehv_bc_data *bc = ttys->driver_data;583 584 /* If there is any data in the queue when the RX interrupt is enabled,585 * we'll immediately get an RX interrupt.586 */587 enable_irq(bc->rx_irq);588}589 590static void ehv_bc_tty_hangup(struct tty_struct *ttys)591{592 struct ehv_bc_data *bc = ttys->driver_data;593 594 ehv_bc_tx_dequeue(bc);595 tty_port_hangup(&bc->port);596}597 598/*599 * TTY driver operations600 *601 * If we could ask the hypervisor how much data is still in the TX buffer, or602 * at least how big the TX buffers are, then we could implement the603 * .wait_until_sent and .chars_in_buffer functions.604 */605static const struct tty_operations ehv_bc_ops = {606 .open = ehv_bc_tty_open,607 .close = ehv_bc_tty_close,608 .write = ehv_bc_tty_write,609 .write_room = ehv_bc_tty_write_room,610 .throttle = ehv_bc_tty_throttle,611 .unthrottle = ehv_bc_tty_unthrottle,612 .hangup = ehv_bc_tty_hangup,613};614 615/*616 * initialize the TTY port617 *618 * This function will only be called once, no matter how many times619 * ehv_bc_tty_open() is called. That's why we register the ISR here, and also620 * why we initialize tty_struct-related variables here.621 */622static int ehv_bc_tty_port_activate(struct tty_port *port,623 struct tty_struct *ttys)624{625 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);626 int ret;627 628 ttys->driver_data = bc;629 630 ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);631 if (ret < 0) {632 dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",633 bc->rx_irq, ret);634 return ret;635 }636 637 /* request_irq also enables the IRQ */638 bc->tx_irq_enabled = 1;639 640 ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);641 if (ret < 0) {642 dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",643 bc->tx_irq, ret);644 free_irq(bc->rx_irq, bc);645 return ret;646 }647 648 /* The TX IRQ is enabled only when we can't write all the data to the649 * byte channel at once, so by default it's disabled.650 */651 disable_tx_interrupt(bc);652 653 return 0;654}655 656static void ehv_bc_tty_port_shutdown(struct tty_port *port)657{658 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);659 660 free_irq(bc->tx_irq, bc);661 free_irq(bc->rx_irq, bc);662}663 664static const struct tty_port_operations ehv_bc_tty_port_ops = {665 .activate = ehv_bc_tty_port_activate,666 .shutdown = ehv_bc_tty_port_shutdown,667};668 669static int ehv_bc_tty_probe(struct platform_device *pdev)670{671 struct device_node *np = pdev->dev.of_node;672 struct ehv_bc_data *bc;673 const uint32_t *iprop;674 unsigned int handle;675 int ret;676 static unsigned int index = 1;677 unsigned int i;678 679 iprop = of_get_property(np, "hv-handle", NULL);680 if (!iprop) {681 dev_err(&pdev->dev, "no 'hv-handle' property in %pOFn node\n",682 np);683 return -ENODEV;684 }685 686 /* We already told the console layer that the index for the console687 * device is zero, so we need to make sure that we use that index when688 * we probe the console byte channel node.689 */690 handle = be32_to_cpu(*iprop);691 i = (handle == stdout_bc) ? 0 : index++;692 bc = &bcs[i];693 694 bc->handle = handle;695 bc->head = 0;696 bc->tail = 0;697 spin_lock_init(&bc->lock);698 699 bc->rx_irq = irq_of_parse_and_map(np, 0);700 bc->tx_irq = irq_of_parse_and_map(np, 1);701 if (!bc->rx_irq || !bc->tx_irq) {702 dev_err(&pdev->dev, "no 'interrupts' property in %pOFn node\n",703 np);704 ret = -ENODEV;705 goto error;706 }707 708 tty_port_init(&bc->port);709 bc->port.ops = &ehv_bc_tty_port_ops;710 711 bc->dev = tty_port_register_device(&bc->port, ehv_bc_driver, i,712 &pdev->dev);713 if (IS_ERR(bc->dev)) {714 ret = PTR_ERR(bc->dev);715 dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);716 goto error;717 }718 719 dev_set_drvdata(&pdev->dev, bc);720 721 dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",722 ehv_bc_driver->name, i, bc->handle);723 724 return 0;725 726error:727 tty_port_destroy(&bc->port);728 irq_dispose_mapping(bc->tx_irq);729 irq_dispose_mapping(bc->rx_irq);730 731 memset(bc, 0, sizeof(struct ehv_bc_data));732 return ret;733}734 735static const struct of_device_id ehv_bc_tty_of_ids[] = {736 { .compatible = "epapr,hv-byte-channel" },737 {}738};739 740static struct platform_driver ehv_bc_tty_driver = {741 .driver = {742 .name = "ehv-bc",743 .of_match_table = ehv_bc_tty_of_ids,744 .suppress_bind_attrs = true,745 },746 .probe = ehv_bc_tty_probe,747};748 749/**750 * ehv_bc_init - ePAPR hypervisor byte channel driver initialization751 *752 * This function is called when this driver is loaded.753 */754static int __init ehv_bc_init(void)755{756 struct tty_driver *driver;757 struct device_node *np;758 unsigned int count = 0; /* Number of elements in bcs[] */759 int ret;760 761 pr_info("ePAPR hypervisor byte channel driver\n");762 763 /* Count the number of byte channels */764 for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")765 count++;766 767 if (!count)768 return -ENODEV;769 770 /* The array index of an element in bcs[] is the same as the tty index771 * for that element. If you know the address of an element in the772 * array, then you can use pointer math (e.g. "bc - bcs") to get its773 * tty index.774 */775 bcs = kcalloc(count, sizeof(struct ehv_bc_data), GFP_KERNEL);776 if (!bcs)777 return -ENOMEM;778 779 driver = tty_alloc_driver(count, TTY_DRIVER_REAL_RAW |780 TTY_DRIVER_DYNAMIC_DEV);781 if (IS_ERR(driver)) {782 ret = PTR_ERR(driver);783 goto err_free_bcs;784 }785 786 driver->driver_name = "ehv-bc";787 driver->name = ehv_bc_console.name;788 driver->type = TTY_DRIVER_TYPE_CONSOLE;789 driver->subtype = SYSTEM_TYPE_CONSOLE;790 driver->init_termios = tty_std_termios;791 tty_set_operations(driver, &ehv_bc_ops);792 793 ret = tty_register_driver(driver);794 if (ret) {795 pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);796 goto err_tty_driver_kref_put;797 }798 799 ehv_bc_driver = driver;800 801 ret = platform_driver_register(&ehv_bc_tty_driver);802 if (ret) {803 pr_err("ehv-bc: could not register platform driver (ret=%i)\n",804 ret);805 goto err_deregister_tty_driver;806 }807 808 return 0;809 810err_deregister_tty_driver:811 ehv_bc_driver = NULL;812 tty_unregister_driver(driver);813err_tty_driver_kref_put:814 tty_driver_kref_put(driver);815err_free_bcs:816 kfree(bcs);817 818 return ret;819}820device_initcall(ehv_bc_init);821