linux/drivers/tty/ehv_bytechan.c
Linus Torvalds e6b5be2be4 Driver core patches for 3.19-rc1
Here's the set of driver core patches for 3.19-rc1.
 
 They are dominated by the removal of the .owner field in platform
 drivers.  They touch a lot of files, but they are "simple" changes, just
 removing a line in a structure.
 
 Other than that, a few minor driver core and debugfs changes.  There are
 some ath9k patches coming in through this tree that have been acked by
 the wireless maintainers as they relied on the debugfs changes.
 
 Everything has been in linux-next for a while.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core update from Greg KH:
 "Here's the set of driver core patches for 3.19-rc1.

  They are dominated by the removal of the .owner field in platform
  drivers.  They touch a lot of files, but they are "simple" changes,
  just removing a line in a structure.

  Other than that, a few minor driver core and debugfs changes.  There
  are some ath9k patches coming in through this tree that have been
  acked by the wireless maintainers as they relied on the debugfs
  changes.

  Everything has been in linux-next for a while"

* tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits)
  Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries"
  fs: debugfs: add forward declaration for struct device type
  firmware class: Deletion of an unnecessary check before the function call "vunmap"
  firmware loader: fix hung task warning dump
  devcoredump: provide a one-way disable function
  device: Add dev_<level>_once variants
  ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries
  ath: use seq_file api for ath9k debugfs files
  debugfs: add helper function to create device related seq_file
  drivers/base: cacheinfo: remove noisy error boot message
  Revert "core: platform: add warning if driver has no owner"
  drivers: base: support cpu cache information interface to userspace via sysfs
  drivers: base: add cpu_device_create to support per-cpu devices
  topology: replace custom attribute macros with standard DEVICE_ATTR*
  cpumask: factor out show_cpumap into separate helper function
  driver core: Fix unbalanced device reference in drivers_probe
  driver core: fix race with userland in device_add()
  sysfs/kernfs: make read requests on pre-alloc files use the buffer.
  sysfs/kernfs: allow attributes to request write buffer be pre-allocated.
  fs: sysfs: return EGBIG on write if offset is larger than file size
  ...
2014-12-14 16:10:09 -08:00

839 lines
22 KiB
C

/* ePAPR hypervisor byte channel device driver
*
* Copyright 2009-2011 Freescale Semiconductor, Inc.
*
* Author: Timur Tabi <timur@freescale.com>
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program is licensed "as is" without any warranty of any
* kind, whether express or implied.
*
* This driver support three distinct interfaces, all of which are related to
* ePAPR hypervisor byte channels.
*
* 1) An early-console (udbg) driver. This provides early console output
* through a byte channel. The byte channel handle must be specified in a
* Kconfig option.
*
* 2) A normal console driver. Output is sent to the byte channel designated
* for stdout in the device tree. The console driver is for handling kernel
* printk calls.
*
* 3) A tty driver, which is used to handle user-space input and output. The
* byte channel used for the console is designated as the default tty.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <asm/epapr_hcalls.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/circ_buf.h>
#include <asm/udbg.h>
/* The size of the transmit circular buffer. This must be a power of two. */
#define BUF_SIZE 2048
/* Per-byte channel private data */
struct ehv_bc_data {
struct device *dev;
struct tty_port port;
uint32_t handle;
unsigned int rx_irq;
unsigned int tx_irq;
spinlock_t lock; /* lock for transmit buffer */
unsigned char buf[BUF_SIZE]; /* transmit circular buffer */
unsigned int head; /* circular buffer head */
unsigned int tail; /* circular buffer tail */
int tx_irq_enabled; /* true == TX interrupt is enabled */
};
/* Array of byte channel objects */
static struct ehv_bc_data *bcs;
/* Byte channel handle for stdout (and stdin), taken from device tree */
static unsigned int stdout_bc;
/* Virtual IRQ for the byte channel handle for stdin, taken from device tree */
static unsigned int stdout_irq;
/**************************** SUPPORT FUNCTIONS ****************************/
/*
* Enable the transmit interrupt
*
* Unlike a serial device, byte channels have no mechanism for disabling their
* own receive or transmit interrupts. To emulate that feature, we toggle
* the IRQ in the kernel.
*
* We cannot just blindly call enable_irq() or disable_irq(), because these
* calls are reference counted. This means that we cannot call enable_irq()
* if interrupts are already enabled. This can happen in two situations:
*
* 1. The tty layer makes two back-to-back calls to ehv_bc_tty_write()
* 2. A transmit interrupt occurs while executing ehv_bc_tx_dequeue()
*
* To work around this, we keep a flag to tell us if the IRQ is enabled or not.
*/
static void enable_tx_interrupt(struct ehv_bc_data *bc)
{
if (!bc->tx_irq_enabled) {
enable_irq(bc->tx_irq);
bc->tx_irq_enabled = 1;
}
}
static void disable_tx_interrupt(struct ehv_bc_data *bc)
{
if (bc->tx_irq_enabled) {
disable_irq_nosync(bc->tx_irq);
bc->tx_irq_enabled = 0;
}
}
/*
* find the byte channel handle to use for the console
*
* The byte channel to be used for the console is specified via a "stdout"
* property in the /chosen node.
*/
static int find_console_handle(void)
{
struct device_node *np = of_stdout;
const char *sprop = NULL;
const uint32_t *iprop;
/* We don't care what the aliased node is actually called. We only
* care if it's compatible with "epapr,hv-byte-channel", because that
* indicates that it's a byte channel node.
*/
if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))
return 0;
stdout_irq = irq_of_parse_and_map(np, 0);
if (stdout_irq == NO_IRQ) {
pr_err("ehv-bc: no 'interrupts' property in %s node\n", np->full_name);
return 0;
}
/*
* The 'hv-handle' property contains the handle for this byte channel.
*/
iprop = of_get_property(np, "hv-handle", NULL);
if (!iprop) {
pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
np->name);
return 0;
}
stdout_bc = be32_to_cpu(*iprop);
return 1;
}
/*************************** EARLY CONSOLE DRIVER ***************************/
#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
/*
* send a byte to a byte channel, wait if necessary
*
* This function sends a byte to a byte channel, and it waits and
* retries if the byte channel is full. It returns if the character
* has been sent, or if some error has occurred.
*
*/
static void byte_channel_spin_send(const char data)
{
int ret, count;
do {
count = 1;
ret = ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
&count, &data);
} while (ret == EV_EAGAIN);
}
/*
* The udbg subsystem calls this function to display a single character.
* We convert CR to a CR/LF.
*/
static void ehv_bc_udbg_putc(char c)
{
if (c == '\n')
byte_channel_spin_send('\r');
byte_channel_spin_send(c);
}
/*
* early console initialization
*
* PowerPC kernels support an early printk console, also known as udbg.
* This function must be called via the ppc_md.init_early function pointer.
* At this point, the device tree has been unflattened, so we can obtain the
* byte channel handle for stdout.
*
* We only support displaying of characters (putc). We do not support
* keyboard input.
*/
void __init udbg_init_ehv_bc(void)
{
unsigned int rx_count, tx_count;
unsigned int ret;
/* Verify the byte channel handle */
ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
&rx_count, &tx_count);
if (ret)
return;
udbg_putc = ehv_bc_udbg_putc;
register_early_udbg_console();
udbg_printf("ehv-bc: early console using byte channel handle %u\n",
CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
}
#endif
/****************************** CONSOLE DRIVER ******************************/
static struct tty_driver *ehv_bc_driver;
/*
* Byte channel console sending worker function.
*
* For consoles, if the output buffer is full, we should just spin until it
* clears.
*/
static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,
unsigned int count)
{
unsigned int len;
int ret = 0;
while (count) {
len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);
do {
ret = ev_byte_channel_send(handle, &len, s);
} while (ret == EV_EAGAIN);
count -= len;
s += len;
}
return ret;
}
/*
* write a string to the console
*
* This function gets called to write a string from the kernel, typically from
* a printk(). This function spins until all data is written.
*
* We copy the data to a temporary buffer because we need to insert a \r in
* front of every \n. It's more efficient to copy the data to the buffer than
* it is to make multiple hcalls for each character or each newline.
*/
static void ehv_bc_console_write(struct console *co, const char *s,
unsigned int count)
{
char s2[EV_BYTE_CHANNEL_MAX_BYTES];
unsigned int i, j = 0;
char c;
for (i = 0; i < count; i++) {
c = *s++;
if (c == '\n')
s2[j++] = '\r';
s2[j++] = c;
if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {
if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j))
return;
j = 0;
}
}
if (j)
ehv_bc_console_byte_channel_send(stdout_bc, s2, j);
}
/*
* When /dev/console is opened, the kernel iterates the console list looking
* for one with ->device and then calls that method. On success, it expects
* the passed-in int* to contain the minor number to use.
*/
static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)
{
*index = co->index;
return ehv_bc_driver;
}
static struct console ehv_bc_console = {
.name = "ttyEHV",
.write = ehv_bc_console_write,
.device = ehv_bc_console_device,
.flags = CON_PRINTBUFFER | CON_ENABLED,
};
/*
* Console initialization
*
* This is the first function that is called after the device tree is
* available, so here is where we determine the byte channel handle and IRQ for
* stdout/stdin, even though that information is used by the tty and character
* drivers.
*/
static int __init ehv_bc_console_init(void)
{
if (!find_console_handle()) {
pr_debug("ehv-bc: stdout is not a byte channel\n");
return -ENODEV;
}
#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
/* Print a friendly warning if the user chose the wrong byte channel
* handle for udbg.
*/
if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)
pr_warn("ehv-bc: udbg handle %u is not the stdout handle\n",
CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
#endif
/* add_preferred_console() must be called before register_console(),
otherwise it won't work. However, we don't want to enumerate all the
byte channels here, either, since we only care about one. */
add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);
register_console(&ehv_bc_console);
pr_info("ehv-bc: registered console driver for byte channel %u\n",
stdout_bc);
return 0;
}
console_initcall(ehv_bc_console_init);
/******************************** TTY DRIVER ********************************/
/*
* byte channel receive interupt handler
*
* This ISR is called whenever data is available on a byte channel.
*/
static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
{
struct ehv_bc_data *bc = data;
unsigned int rx_count, tx_count, len;
int count;
char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
int ret;
/* Find out how much data needs to be read, and then ask the TTY layer
* if it can handle that much. We want to ensure that every byte we
* read from the byte channel will be accepted by the TTY layer.
*/
ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);
count = tty_buffer_request_room(&bc->port, rx_count);
/* 'count' is the maximum amount of data the TTY layer can accept at
* this time. However, during testing, I was never able to get 'count'
* to be less than 'rx_count'. I'm not sure whether I'm calling it
* correctly.
*/
while (count > 0) {
len = min_t(unsigned int, count, sizeof(buffer));
/* Read some data from the byte channel. This function will
* never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.
*/
ev_byte_channel_receive(bc->handle, &len, buffer);
/* 'len' is now the amount of data that's been received. 'len'
* can't be zero, and most likely it's equal to one.
*/
/* Pass the received data to the tty layer. */
ret = tty_insert_flip_string(&bc->port, buffer, len);
/* 'ret' is the number of bytes that the TTY layer accepted.
* If it's not equal to 'len', then it means the buffer is
* full, which should never happen. If it does happen, we can
* exit gracefully, but we drop the last 'len - ret' characters
* that we read from the byte channel.
*/
if (ret != len)
break;
count -= len;
}
/* Tell the tty layer that we're done. */
tty_flip_buffer_push(&bc->port);
return IRQ_HANDLED;
}
/*
* dequeue the transmit buffer to the hypervisor
*
* This function, which can be called in interrupt context, dequeues as much
* data as possible from the transmit buffer to the byte channel.
*/
static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)
{
unsigned int count;
unsigned int len, ret;
unsigned long flags;
do {
spin_lock_irqsave(&bc->lock, flags);
len = min_t(unsigned int,
CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
EV_BYTE_CHANNEL_MAX_BYTES);
ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);
/* 'len' is valid only if the return code is 0 or EV_EAGAIN */
if (!ret || (ret == EV_EAGAIN))
bc->tail = (bc->tail + len) & (BUF_SIZE - 1);
count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);
spin_unlock_irqrestore(&bc->lock, flags);
} while (count && !ret);
spin_lock_irqsave(&bc->lock, flags);
if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))
/*
* If we haven't emptied the buffer, then enable the TX IRQ.
* We'll get an interrupt when there's more room in the
* hypervisor's output buffer.
*/
enable_tx_interrupt(bc);
else
disable_tx_interrupt(bc);
spin_unlock_irqrestore(&bc->lock, flags);
}
/*
* byte channel transmit interupt handler
*
* This ISR is called whenever space becomes available for transmitting
* characters on a byte channel.
*/
static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
{
struct ehv_bc_data *bc = data;
ehv_bc_tx_dequeue(bc);
tty_port_tty_wakeup(&bc->port);
return IRQ_HANDLED;
}
/*
* This function is called when the tty layer has data for us send. We store
* the data first in a circular buffer, and then dequeue as much of that data
* as possible.
*
* We don't need to worry about whether there is enough room in the buffer for
* all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty
* layer how much data it can safely send to us. We guarantee that
* ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
* too much data.
*/
static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s,
int count)
{
struct ehv_bc_data *bc = ttys->driver_data;
unsigned long flags;
unsigned int len;
unsigned int written = 0;
while (1) {
spin_lock_irqsave(&bc->lock, flags);
len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
if (count < len)
len = count;
if (len) {
memcpy(bc->buf + bc->head, s, len);
bc->head = (bc->head + len) & (BUF_SIZE - 1);
}
spin_unlock_irqrestore(&bc->lock, flags);
if (!len)
break;
s += len;
count -= len;
written += len;
}
ehv_bc_tx_dequeue(bc);
return written;
}
/*
* This function can be called multiple times for a given tty_struct, which is
* why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.
*
* The tty layer will still call this function even if the device was not
* registered (i.e. tty_register_device() was not called). This happens
* because tty_register_device() is optional and some legacy drivers don't
* use it. So we need to check for that.
*/
static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)
{
struct ehv_bc_data *bc = &bcs[ttys->index];
if (!bc->dev)
return -ENODEV;
return tty_port_open(&bc->port, ttys, filp);
}
/*
* Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will
* still call this function to close the tty device. So we can't assume that
* the tty port has been initialized.
*/
static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)
{
struct ehv_bc_data *bc = &bcs[ttys->index];
if (bc->dev)
tty_port_close(&bc->port, ttys, filp);
}
/*
* Return the amount of space in the output buffer
*
* This is actually a contract between the driver and the tty layer outlining
* how much write room the driver can guarantee will be sent OR BUFFERED. This
* driver MUST honor the return value.
*/
static int ehv_bc_tty_write_room(struct tty_struct *ttys)
{
struct ehv_bc_data *bc = ttys->driver_data;
unsigned long flags;
int count;
spin_lock_irqsave(&bc->lock, flags);
count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
spin_unlock_irqrestore(&bc->lock, flags);
return count;
}
/*
* Stop sending data to the tty layer
*
* This function is called when the tty layer's input buffers are getting full,
* so the driver should stop sending it data. The easiest way to do this is to
* disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being
* called.
*
* The hypervisor will continue to queue up any incoming data. If there is any
* data in the queue when the RX interrupt is enabled, we'll immediately get an
* RX interrupt.
*/
static void ehv_bc_tty_throttle(struct tty_struct *ttys)
{
struct ehv_bc_data *bc = ttys->driver_data;
disable_irq(bc->rx_irq);
}
/*
* Resume sending data to the tty layer
*
* This function is called after previously calling ehv_bc_tty_throttle(). The
* tty layer's input buffers now have more room, so the driver can resume
* sending it data.
*/
static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)
{
struct ehv_bc_data *bc = ttys->driver_data;
/* If there is any data in the queue when the RX interrupt is enabled,
* we'll immediately get an RX interrupt.
*/
enable_irq(bc->rx_irq);
}
static void ehv_bc_tty_hangup(struct tty_struct *ttys)
{
struct ehv_bc_data *bc = ttys->driver_data;
ehv_bc_tx_dequeue(bc);
tty_port_hangup(&bc->port);
}
/*
* TTY driver operations
*
* If we could ask the hypervisor how much data is still in the TX buffer, or
* at least how big the TX buffers are, then we could implement the
* .wait_until_sent and .chars_in_buffer functions.
*/
static const struct tty_operations ehv_bc_ops = {
.open = ehv_bc_tty_open,
.close = ehv_bc_tty_close,
.write = ehv_bc_tty_write,
.write_room = ehv_bc_tty_write_room,
.throttle = ehv_bc_tty_throttle,
.unthrottle = ehv_bc_tty_unthrottle,
.hangup = ehv_bc_tty_hangup,
};
/*
* initialize the TTY port
*
* This function will only be called once, no matter how many times
* ehv_bc_tty_open() is called. That's why we register the ISR here, and also
* why we initialize tty_struct-related variables here.
*/
static int ehv_bc_tty_port_activate(struct tty_port *port,
struct tty_struct *ttys)
{
struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
int ret;
ttys->driver_data = bc;
ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);
if (ret < 0) {
dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",
bc->rx_irq, ret);
return ret;
}
/* request_irq also enables the IRQ */
bc->tx_irq_enabled = 1;
ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);
if (ret < 0) {
dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",
bc->tx_irq, ret);
free_irq(bc->rx_irq, bc);
return ret;
}
/* The TX IRQ is enabled only when we can't write all the data to the
* byte channel at once, so by default it's disabled.
*/
disable_tx_interrupt(bc);
return 0;
}
static void ehv_bc_tty_port_shutdown(struct tty_port *port)
{
struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
free_irq(bc->tx_irq, bc);
free_irq(bc->rx_irq, bc);
}
static const struct tty_port_operations ehv_bc_tty_port_ops = {
.activate = ehv_bc_tty_port_activate,
.shutdown = ehv_bc_tty_port_shutdown,
};
static int ehv_bc_tty_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct ehv_bc_data *bc;
const uint32_t *iprop;
unsigned int handle;
int ret;
static unsigned int index = 1;
unsigned int i;
iprop = of_get_property(np, "hv-handle", NULL);
if (!iprop) {
dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n",
np->name);
return -ENODEV;
}
/* We already told the console layer that the index for the console
* device is zero, so we need to make sure that we use that index when
* we probe the console byte channel node.
*/
handle = be32_to_cpu(*iprop);
i = (handle == stdout_bc) ? 0 : index++;
bc = &bcs[i];
bc->handle = handle;
bc->head = 0;
bc->tail = 0;
spin_lock_init(&bc->lock);
bc->rx_irq = irq_of_parse_and_map(np, 0);
bc->tx_irq = irq_of_parse_and_map(np, 1);
if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) {
dev_err(&pdev->dev, "no 'interrupts' property in %s node\n",
np->name);
ret = -ENODEV;
goto error;
}
tty_port_init(&bc->port);
bc->port.ops = &ehv_bc_tty_port_ops;
bc->dev = tty_port_register_device(&bc->port, ehv_bc_driver, i,
&pdev->dev);
if (IS_ERR(bc->dev)) {
ret = PTR_ERR(bc->dev);
dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);
goto error;
}
dev_set_drvdata(&pdev->dev, bc);
dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",
ehv_bc_driver->name, i, bc->handle);
return 0;
error:
tty_port_destroy(&bc->port);
irq_dispose_mapping(bc->tx_irq);
irq_dispose_mapping(bc->rx_irq);
memset(bc, 0, sizeof(struct ehv_bc_data));
return ret;
}
static int ehv_bc_tty_remove(struct platform_device *pdev)
{
struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev);
tty_unregister_device(ehv_bc_driver, bc - bcs);
tty_port_destroy(&bc->port);
irq_dispose_mapping(bc->tx_irq);
irq_dispose_mapping(bc->rx_irq);
return 0;
}
static const struct of_device_id ehv_bc_tty_of_ids[] = {
{ .compatible = "epapr,hv-byte-channel" },
{}
};
static struct platform_driver ehv_bc_tty_driver = {
.driver = {
.name = "ehv-bc",
.of_match_table = ehv_bc_tty_of_ids,
},
.probe = ehv_bc_tty_probe,
.remove = ehv_bc_tty_remove,
};
/**
* ehv_bc_init - ePAPR hypervisor byte channel driver initialization
*
* This function is called when this module is loaded.
*/
static int __init ehv_bc_init(void)
{
struct device_node *np;
unsigned int count = 0; /* Number of elements in bcs[] */
int ret;
pr_info("ePAPR hypervisor byte channel driver\n");
/* Count the number of byte channels */
for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")
count++;
if (!count)
return -ENODEV;
/* The array index of an element in bcs[] is the same as the tty index
* for that element. If you know the address of an element in the
* array, then you can use pointer math (e.g. "bc - bcs") to get its
* tty index.
*/
bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL);
if (!bcs)
return -ENOMEM;
ehv_bc_driver = alloc_tty_driver(count);
if (!ehv_bc_driver) {
ret = -ENOMEM;
goto error;
}
ehv_bc_driver->driver_name = "ehv-bc";
ehv_bc_driver->name = ehv_bc_console.name;
ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE;
ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE;
ehv_bc_driver->init_termios = tty_std_termios;
ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
tty_set_operations(ehv_bc_driver, &ehv_bc_ops);
ret = tty_register_driver(ehv_bc_driver);
if (ret) {
pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);
goto error;
}
ret = platform_driver_register(&ehv_bc_tty_driver);
if (ret) {
pr_err("ehv-bc: could not register platform driver (ret=%i)\n",
ret);
goto error;
}
return 0;
error:
if (ehv_bc_driver) {
tty_unregister_driver(ehv_bc_driver);
put_tty_driver(ehv_bc_driver);
}
kfree(bcs);
return ret;
}
/**
* ehv_bc_exit - ePAPR hypervisor byte channel driver termination
*
* This function is called when this driver is unloaded.
*/
static void __exit ehv_bc_exit(void)
{
platform_driver_unregister(&ehv_bc_tty_driver);
tty_unregister_driver(ehv_bc_driver);
put_tty_driver(ehv_bc_driver);
kfree(bcs);
}
module_init(ehv_bc_init);
module_exit(ehv_bc_exit);
MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
MODULE_LICENSE("GPL v2");