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android_kernel_xiaomi_sm8350/drivers/char/hvcs.c
Benjamin Herrenschmidt 187cfc439f hvc_console: Remove tty->low_latency on pseries backends 
The hvcs and hvsi backends both set tty->low_latency to one, along
with more or less scary comments regarding bugs or races that would
happen if not doing so.

However, they also both call tty_flip_buffer_push() in conexts where
it's illegal to do so since some recent tty changes (or at least it
may have been illegal always but it nows blows) when low_latency is
set (ie, hard interrupt or with spinlock held and irqs disabled).

This removes the setting for now to get them back to working condition,
we'll have to address the races described in the comments separately
if they are still an issue (some of this might have been fixed already).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-03-11 10:44:26 +11:00

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/*
* IBM eServer Hypervisor Virtual Console Server Device Driver
* Copyright (C) 2003, 2004 IBM Corp.
* Ryan S. Arnold (rsa@us.ibm.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author(s) : Ryan S. Arnold <rsa@us.ibm.com>
*
* This is the device driver for the IBM Hypervisor Virtual Console Server,
* "hvcs". The IBM hvcs provides a tty driver interface to allow Linux
* user space applications access to the system consoles of logically
* partitioned operating systems, e.g. Linux, running on the same partitioned
* Power5 ppc64 system. Physical hardware consoles per partition are not
* practical on this hardware so system consoles are accessed by this driver
* using inter-partition firmware interfaces to virtual terminal devices.
*
* A vty is known to the HMC as a "virtual serial server adapter". It is a
* virtual terminal device that is created by firmware upon partition creation
* to act as a partitioned OS's console device.
*
* Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
* Linux system upon their creation by the HMC or their exposure during boot.
* The non-user interactive backend of this driver is implemented as a vio
* device driver so that it can receive notification of vty-server lifetimes
* after it registers with the vio bus to handle vty-server probe and remove
* callbacks.
*
* Many vty-servers can be configured to connect to one vty, but a vty can
* only be actively connected to by a single vty-server, in any manner, at one
* time. If the HMC is currently hosting the console for a target Linux
* partition; attempts to open the tty device to the partition's console using
* the hvcs on any partition will return -EBUSY with every open attempt until
* the HMC frees the connection between its vty-server and the desired
* partition's vty device. Conversely, a vty-server may only be connected to
* a single vty at one time even though it may have several configured vty
* partner possibilities.
*
* Firmware does not provide notification of vty partner changes to this
* driver. This means that an HMC Super Admin may add or remove partner vtys
* from a vty-server's partner list but the changes will not be signaled to
* the vty-server. Firmware only notifies the driver when a vty-server is
* added or removed from the system. To compensate for this deficiency, this
* driver implements a sysfs update attribute which provides a method for
* rescanning partner information upon a user's request.
*
* Each vty-server, prior to being exposed to this driver is reference counted
* using the 2.6 Linux kernel kref construct.
*
* For direction on installation and usage of this driver please reference
* Documentation/powerpc/hvcs.txt.
*/
#include <linux/device.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/major.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <asm/hvconsole.h>
#include <asm/hvcserver.h>
#include <asm/uaccess.h>
#include <asm/vio.h>
/*
* 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
* Removed braces around single statements following conditionals. Removed '=
* 0' after static int declarations since these default to zero. Removed
* list_for_each_safe() and replaced with list_for_each_entry() in
* hvcs_get_by_index(). The 'safe' version is un-needed now that the driver is
* using spinlocks. Changed spin_lock_irqsave() to spin_lock() when locking
* hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
* handler. Initialized hvcs_structs_lock and hvcs_pi_lock to
* SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
* Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
* list traversals from a deletion. Removed '= NULL' from pointer declaration
* statements since they are initialized NULL by default. Removed wmb()
* instances from hvcs_try_write(). They probably aren't needed with locking in
* place. Added check and cleanup for hvcs_pi_buff = kmalloc() in
* hvcs_module_init(). Exposed hvcs_struct.index via a sysfs attribute so that
* the coupling between /dev/hvcs* and a vty-server can be automatically
* determined. Moved kobject_put() in hvcs_open outside of the
* spin_unlock_irqrestore().
*
* 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
* align with how the tty layer always assigns the lowest index available. This
* change resulted in a list of ints that denotes which indexes are available.
* Device additions and removals use the new hvcs_get_index() and
* hvcs_return_index() helper functions. The list is created with
* hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
* Without these fixes hotplug vty-server adapter support goes crazy with this
* driver if the user removes a vty-server adapter. Moved free_irq() outside of
* the hvcs_final_close() function in order to get it out of the spinlock.
* Rearranged hvcs_close(). Cleaned up some printks and did some housekeeping
* on the changelog. Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
* arch/powerepc/include/asm/hvcserver.h
*
* 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
* prevent possible lockup with realtime scheduling as similarily pointed out by
* akpm in hvc_console. Changed resulted in the removal of hvcs_final_close()
* to reorder cleanup operations and prevent discarding of pending data during
* an hvcs_close(). Removed spinlock protection of hvcs_struct data members in
* hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
*/
#define HVCS_DRIVER_VERSION "1.3.3"
MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(HVCS_DRIVER_VERSION);
/*
* Wait this long per iteration while trying to push buffered data to the
* hypervisor before allowing the tty to complete a close operation.
*/
#define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
/*
* Since the Linux TTY code does not currently (2-04-2004) support dynamic
* addition of tty derived devices and we shouldn't allocate thousands of
* tty_device pointers when the number of vty-server & vty partner connections
* will most often be much lower than this, we'll arbitrarily allocate
* HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
* register the tty_driver. This can be overridden using an insmod parameter.
*/
#define HVCS_DEFAULT_SERVER_ADAPTERS 64
/*
* The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
* nodes as a sanity check. Theoretically there can be over 1 Billion
* vty-server & vty partner connections.
*/
#define HVCS_MAX_SERVER_ADAPTERS 1024
/*
* We let Linux assign us a major number and we start the minors at zero. There
* is no intuitive mapping between minor number and the target vty-server
* adapter except that each new vty-server adapter is always assigned to the
* smallest minor number available.
*/
#define HVCS_MINOR_START 0
/*
* The hcall interface involves putting 8 chars into each of two registers.
* We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
* by casting char[16] to long[2]. It would work without __ALIGNED__, but a
* little (tiny) bit slower because an unaligned load is slower than aligned
* load.
*/
#define __ALIGNED__ __attribute__((__aligned__(8)))
/*
* How much data can firmware send with each hvc_put_chars()? Maybe this
* should be moved into an architecture specific area.
*/
#define HVCS_BUFF_LEN 16
/*
* This is the maximum amount of data we'll let the user send us (hvcs_write) at
* once in a chunk as a sanity check.
*/
#define HVCS_MAX_FROM_USER 4096
/*
* Be careful when adding flags to this line discipline. Don't add anything
* that will cause echoing or we'll go into recursive loop echoing chars back
* and forth with the console drivers.
*/
static struct ktermios hvcs_tty_termios = {
.c_iflag = IGNBRK | IGNPAR,
.c_oflag = OPOST,
.c_cflag = B38400 | CS8 | CREAD | HUPCL,
.c_cc = INIT_C_CC,
.c_ispeed = 38400,
.c_ospeed = 38400
};
/*
* This value is used to take the place of a command line parameter when the
* module is inserted. It starts as -1 and stays as such if the user doesn't
* specify a module insmod parameter. If they DO specify one then it is set to
* the value of the integer passed in.
*/
static int hvcs_parm_num_devs = -1;
module_param(hvcs_parm_num_devs, int, 0);
static const char hvcs_driver_name[] = "hvcs";
static const char hvcs_device_node[] = "hvcs";
static const char hvcs_driver_string[]
= "IBM hvcs (Hypervisor Virtual Console Server) Driver";
/* Status of partner info rescan triggered via sysfs. */
static int hvcs_rescan_status;
static struct tty_driver *hvcs_tty_driver;
/*
* In order to be somewhat sane this driver always associates the hvcs_struct
* index element with the numerically equal tty->index. This means that a
* hotplugged vty-server adapter will always map to the lowest index valued
* device node. If vty-servers were hotplug removed from the system and then
* new ones added the new vty-server may have the largest slot number of all
* the vty-server adapters in the partition but it may have the lowest dev node
* index of all the adapters due to the hole left by the hotplug removed
* adapter. There are a set of functions provided to get the lowest index for
* a new device as well as return the index to the list. This list is allocated
* with a number of elements equal to the number of device nodes requested when
* the module was inserted.
*/
static int *hvcs_index_list;
/*
* How large is the list? This is kept for traversal since the list is
* dynamically created.
*/
static int hvcs_index_count;
/*
* Used by the khvcsd to pick up I/O operations when the kernel_thread is
* already awake but potentially shifted to TASK_INTERRUPTIBLE state.
*/
static int hvcs_kicked;
/*
* Use by the kthread construct for task operations like waking the sleeping
* thread and stopping the kthread.
*/
static struct task_struct *hvcs_task;
/*
* We allocate this for the use of all of the hvcs_structs when they fetch
* partner info.
*/
static unsigned long *hvcs_pi_buff;
/* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
static DEFINE_SPINLOCK(hvcs_pi_lock);
/* One vty-server per hvcs_struct */
struct hvcs_struct {
spinlock_t lock;
/*
* This index identifies this hvcs device as the complement to a
* specific tty index.
*/
unsigned int index;
struct tty_struct *tty;
int open_count;
/*
* Used to tell the driver kernel_thread what operations need to take
* place upon this hvcs_struct instance.
*/
int todo_mask;
/*
* This buffer is required so that when hvcs_write_room() reports that
* it can send HVCS_BUFF_LEN characters that it will buffer the full
* HVCS_BUFF_LEN characters if need be. This is essential for opost
* writes since they do not do high level buffering and expect to be
* able to send what the driver commits to sending buffering
* [e.g. tab to space conversions in n_tty.c opost()].
*/
char buffer[HVCS_BUFF_LEN];
int chars_in_buffer;
/*
* Any variable below the kref is valid before a tty is connected and
* stays valid after the tty is disconnected. These shouldn't be
* whacked until the koject refcount reaches zero though some entries
* may be changed via sysfs initiatives.
*/
struct kref kref; /* ref count & hvcs_struct lifetime */
int connected; /* is the vty-server currently connected to a vty? */
uint32_t p_unit_address; /* partner unit address */
uint32_t p_partition_ID; /* partner partition ID */
char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
struct list_head next; /* list management */
struct vio_dev *vdev;
};
/* Required to back map a kref to its containing object */
#define from_kref(k) container_of(k, struct hvcs_struct, kref)
static LIST_HEAD(hvcs_structs);
static DEFINE_SPINLOCK(hvcs_structs_lock);
static void hvcs_unthrottle(struct tty_struct *tty);
static void hvcs_throttle(struct tty_struct *tty);
static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
static int hvcs_write(struct tty_struct *tty,
const unsigned char *buf, int count);
static int hvcs_write_room(struct tty_struct *tty);
static int hvcs_chars_in_buffer(struct tty_struct *tty);
static int hvcs_has_pi(struct hvcs_struct *hvcsd);
static void hvcs_set_pi(struct hvcs_partner_info *pi,
struct hvcs_struct *hvcsd);
static int hvcs_get_pi(struct hvcs_struct *hvcsd);
static int hvcs_rescan_devices_list(void);
static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
static void hvcs_partner_free(struct hvcs_struct *hvcsd);
static int hvcs_enable_device(struct hvcs_struct *hvcsd,
uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
static int hvcs_open(struct tty_struct *tty, struct file *filp);
static void hvcs_close(struct tty_struct *tty, struct file *filp);
static void hvcs_hangup(struct tty_struct * tty);
static int __devinit hvcs_probe(struct vio_dev *dev,
const struct vio_device_id *id);
static int __devexit hvcs_remove(struct vio_dev *dev);
static int __init hvcs_module_init(void);
static void __exit hvcs_module_exit(void);
#define HVCS_SCHED_READ 0x00000001
#define HVCS_QUICK_READ 0x00000002
#define HVCS_TRY_WRITE 0x00000004
#define HVCS_READ_MASK (HVCS_SCHED_READ | HVCS_QUICK_READ)
static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
{
return viod->dev.driver_data;
}
/* The sysfs interface for the driver and devices */
static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
int retval;
spin_lock_irqsave(&hvcsd->lock, flags);
retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return retval;
}
static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
int retval;
spin_lock_irqsave(&hvcsd->lock, flags);
retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return retval;
}
static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
size_t count)
{
/*
* Don't need this feature at the present time because firmware doesn't
* yet support multiple partners.
*/
printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
return -EPERM;
}
static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
int retval;
spin_lock_irqsave(&hvcsd->lock, flags);
retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return retval;
}
static DEVICE_ATTR(current_vty,
S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
size_t count)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
/* writing a '0' to this sysfs entry will result in the disconnect. */
if (simple_strtol(buf, NULL, 0) != 0)
return -EINVAL;
spin_lock_irqsave(&hvcsd->lock, flags);
if (hvcsd->open_count > 0) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
printk(KERN_INFO "HVCS: vterm state unchanged. "
"The hvcs device node is still in use.\n");
return -EPERM;
}
if (hvcsd->connected == 0) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
printk(KERN_INFO "HVCS: vterm state unchanged. The"
" vty-server is not connected to a vty.\n");
return -EPERM;
}
hvcs_partner_free(hvcsd);
printk(KERN_INFO "HVCS: Closed vty-server@%X and"
" partner vty@%X:%d connection.\n",
hvcsd->vdev->unit_address,
hvcsd->p_unit_address,
(uint32_t)hvcsd->p_partition_ID);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return count;
}
static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
int retval;
spin_lock_irqsave(&hvcsd->lock, flags);
retval = sprintf(buf, "%d\n", hvcsd->connected);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return retval;
}
static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
hvcs_vterm_state_show, hvcs_vterm_state_store);
static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct vio_dev *viod = to_vio_dev(dev);
struct hvcs_struct *hvcsd = from_vio_dev(viod);
unsigned long flags;
int retval;
spin_lock_irqsave(&hvcsd->lock, flags);
retval = sprintf(buf, "%d\n", hvcsd->index);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return retval;
}
static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
static struct attribute *hvcs_attrs[] = {
&dev_attr_partner_vtys.attr,
&dev_attr_partner_clcs.attr,
&dev_attr_current_vty.attr,
&dev_attr_vterm_state.attr,
&dev_attr_index.attr,
NULL,
};
static struct attribute_group hvcs_attr_group = {
.attrs = hvcs_attrs,
};
static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
{
/* A 1 means it is updating, a 0 means it is done updating */
return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
}
static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
size_t count)
{
if ((simple_strtol(buf, NULL, 0) != 1)
&& (hvcs_rescan_status != 0))
return -EINVAL;
hvcs_rescan_status = 1;
printk(KERN_INFO "HVCS: rescanning partner info for all"
" vty-servers.\n");
hvcs_rescan_devices_list();
hvcs_rescan_status = 0;
return count;
}
static DRIVER_ATTR(rescan,
S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
static void hvcs_kick(void)
{
hvcs_kicked = 1;
wmb();
wake_up_process(hvcs_task);
}
static void hvcs_unthrottle(struct tty_struct *tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&hvcsd->lock, flags);
hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);
hvcs_kick();
}
static void hvcs_throttle(struct tty_struct *tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&hvcsd->lock, flags);
vio_disable_interrupts(hvcsd->vdev);
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
/*
* If the device is being removed we don't have to worry about this interrupt
* handler taking any further interrupts because they are disabled which means
* the hvcs_struct will always be valid in this handler.
*/
static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
{
struct hvcs_struct *hvcsd = dev_instance;
spin_lock(&hvcsd->lock);
vio_disable_interrupts(hvcsd->vdev);
hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock(&hvcsd->lock);
hvcs_kick();
return IRQ_HANDLED;
}
/* This function must be called with the hvcsd->lock held */
static void hvcs_try_write(struct hvcs_struct *hvcsd)
{
uint32_t unit_address = hvcsd->vdev->unit_address;
struct tty_struct *tty = hvcsd->tty;
int sent;
if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
/* won't send partial writes */
sent = hvc_put_chars(unit_address,
&hvcsd->buffer[0],
hvcsd->chars_in_buffer );
if (sent > 0) {
hvcsd->chars_in_buffer = 0;
/* wmb(); */
hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
/* wmb(); */
/*
* We are still obligated to deliver the data to the
* hypervisor even if the tty has been closed because
* we commited to delivering it. But don't try to wake
* a non-existent tty.
*/
if (tty) {
tty_wakeup(tty);
}
}
}
}
static int hvcs_io(struct hvcs_struct *hvcsd)
{
uint32_t unit_address;
struct tty_struct *tty;
char buf[HVCS_BUFF_LEN] __ALIGNED__;
unsigned long flags;
int got = 0;
spin_lock_irqsave(&hvcsd->lock, flags);
unit_address = hvcsd->vdev->unit_address;
tty = hvcsd->tty;
hvcs_try_write(hvcsd);
if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
hvcsd->todo_mask &= ~(HVCS_READ_MASK);
goto bail;
} else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
goto bail;
/* remove the read masks */
hvcsd->todo_mask &= ~(HVCS_READ_MASK);
if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
got = hvc_get_chars(unit_address,
&buf[0],
HVCS_BUFF_LEN);
tty_insert_flip_string(tty, buf, got);
}
/* Give the TTY time to process the data we just sent. */
if (got)
hvcsd->todo_mask |= HVCS_QUICK_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);
/* This is synch because tty->low_latency == 1 */
if(got)
tty_flip_buffer_push(tty);
if (!got) {
/* Do this _after_ the flip_buffer_push */
spin_lock_irqsave(&hvcsd->lock, flags);
vio_enable_interrupts(hvcsd->vdev);
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
return hvcsd->todo_mask;
bail:
spin_unlock_irqrestore(&hvcsd->lock, flags);
return hvcsd->todo_mask;
}
static int khvcsd(void *unused)
{
struct hvcs_struct *hvcsd;
int hvcs_todo_mask;
__set_current_state(TASK_RUNNING);
do {
hvcs_todo_mask = 0;
hvcs_kicked = 0;
wmb();
spin_lock(&hvcs_structs_lock);
list_for_each_entry(hvcsd, &hvcs_structs, next) {
hvcs_todo_mask |= hvcs_io(hvcsd);
}
spin_unlock(&hvcs_structs_lock);
/*
* If any of the hvcs adapters want to try a write or quick read
* don't schedule(), yield a smidgen then execute the hvcs_io
* thread again for those that want the write.
*/
if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
yield();
continue;
}
set_current_state(TASK_INTERRUPTIBLE);
if (!hvcs_kicked)
schedule();
__set_current_state(TASK_RUNNING);
} while (!kthread_should_stop());
return 0;
}
static struct vio_device_id hvcs_driver_table[] __devinitdata= {
{"serial-server", "hvterm2"},
{ "", "" }
};
MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
static void hvcs_return_index(int index)
{
/* Paranoia check */
if (!hvcs_index_list)
return;
if (index < 0 || index >= hvcs_index_count)
return;
if (hvcs_index_list[index] == -1)
return;
else
hvcs_index_list[index] = -1;
}
/* callback when the kref ref count reaches zero */
static void destroy_hvcs_struct(struct kref *kref)
{
struct hvcs_struct *hvcsd = from_kref(kref);
struct vio_dev *vdev;
unsigned long flags;
spin_lock(&hvcs_structs_lock);
spin_lock_irqsave(&hvcsd->lock, flags);
/* the list_del poisons the pointers */
list_del(&(hvcsd->next));
if (hvcsd->connected == 1) {
hvcs_partner_free(hvcsd);
printk(KERN_INFO "HVCS: Closed vty-server@%X and"
" partner vty@%X:%d connection.\n",
hvcsd->vdev->unit_address,
hvcsd->p_unit_address,
(uint32_t)hvcsd->p_partition_ID);
}
printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
hvcsd->vdev->unit_address);
vdev = hvcsd->vdev;
hvcsd->vdev = NULL;
hvcsd->p_unit_address = 0;
hvcsd->p_partition_ID = 0;
hvcs_return_index(hvcsd->index);
memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
spin_unlock_irqrestore(&hvcsd->lock, flags);
spin_unlock(&hvcs_structs_lock);
sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
kfree(hvcsd);
}
static int hvcs_get_index(void)
{
int i;
/* Paranoia check */
if (!hvcs_index_list) {
printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
return -EFAULT;
}
/* Find the numerically lowest first free index. */
for(i = 0; i < hvcs_index_count; i++) {
if (hvcs_index_list[i] == -1) {
hvcs_index_list[i] = 0;
return i;
}
}
return -1;
}
static int __devinit hvcs_probe(
struct vio_dev *dev,
const struct vio_device_id *id)
{
struct hvcs_struct *hvcsd;
int index;
int retval;
if (!dev || !id) {
printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
return -EPERM;
}
/* early to avoid cleanup on failure */
index = hvcs_get_index();
if (index < 0) {
return -EFAULT;
}
hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
if (!hvcsd)
return -ENODEV;
spin_lock_init(&hvcsd->lock);
/* Automatically incs the refcount the first time */
kref_init(&hvcsd->kref);
hvcsd->vdev = dev;
dev->dev.driver_data = hvcsd;
hvcsd->index = index;
/* hvcsd->index = ++hvcs_struct_count; */
hvcsd->chars_in_buffer = 0;
hvcsd->todo_mask = 0;
hvcsd->connected = 0;
/*
* This will populate the hvcs_struct's partner info fields for the
* first time.
*/
if (hvcs_get_pi(hvcsd)) {
printk(KERN_ERR "HVCS: Failed to fetch partner"
" info for vty-server@%X on device probe.\n",
hvcsd->vdev->unit_address);
}
/*
* If a user app opens a tty that corresponds to this vty-server before
* the hvcs_struct has been added to the devices list then the user app
* will get -ENODEV.
*/
spin_lock(&hvcs_structs_lock);
list_add_tail(&(hvcsd->next), &hvcs_structs);
spin_unlock(&hvcs_structs_lock);
retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
if (retval) {
printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
hvcsd->vdev->unit_address);
return retval;
}
printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
/*
* DON'T enable interrupts here because there is no user to receive the
* data.
*/
return 0;
}
static int __devexit hvcs_remove(struct vio_dev *dev)
{
struct hvcs_struct *hvcsd = dev->dev.driver_data;
unsigned long flags;
struct tty_struct *tty;
if (!hvcsd)
return -ENODEV;
/* By this time the vty-server won't be getting any more interrupts */
spin_lock_irqsave(&hvcsd->lock, flags);
tty = hvcsd->tty;
spin_unlock_irqrestore(&hvcsd->lock, flags);
/*
* Let the last holder of this object cause it to be removed, which
* would probably be tty_hangup below.
*/
kref_put(&hvcsd->kref, destroy_hvcs_struct);
/*
* The hangup is a scheduled function which will auto chain call
* hvcs_hangup. The tty should always be valid at this time unless a
* simultaneous tty close already cleaned up the hvcs_struct.
*/
if (tty)
tty_hangup(tty);
printk(KERN_INFO "HVCS: vty-server@%X removed from the"
" vio bus.\n", dev->unit_address);
return 0;
};
static struct vio_driver hvcs_vio_driver = {
.id_table = hvcs_driver_table,
.probe = hvcs_probe,
.remove = hvcs_remove,
.driver = {
.name = hvcs_driver_name,
.owner = THIS_MODULE,
}
};
/* Only called from hvcs_get_pi please */
static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
{
int clclength;
hvcsd->p_unit_address = pi->unit_address;
hvcsd->p_partition_ID = pi->partition_ID;
clclength = strlen(&pi->location_code[0]);
if (clclength > HVCS_CLC_LENGTH)
clclength = HVCS_CLC_LENGTH;
/* copy the null-term char too */
strncpy(&hvcsd->p_location_code[0],
&pi->location_code[0], clclength + 1);
}
/*
* Traverse the list and add the partner info that is found to the hvcs_struct
* struct entry. NOTE: At this time I know that partner info will return a
* single entry but in the future there may be multiple partner info entries per
* vty-server and you'll want to zero out that list and reset it. If for some
* reason you have an old version of this driver but there IS more than one
* partner info then hvcsd->p_* will hold the last partner info data from the
* firmware query. A good way to update this code would be to replace the three
* partner info fields in hvcs_struct with a list of hvcs_partner_info
* instances.
*
* This function must be called with the hvcsd->lock held.
*/
static int hvcs_get_pi(struct hvcs_struct *hvcsd)
{
struct hvcs_partner_info *pi;
uint32_t unit_address = hvcsd->vdev->unit_address;
struct list_head head;
int retval;
spin_lock(&hvcs_pi_lock);
if (!hvcs_pi_buff) {
spin_unlock(&hvcs_pi_lock);
return -EFAULT;
}
retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
spin_unlock(&hvcs_pi_lock);
if (retval) {
printk(KERN_ERR "HVCS: Failed to fetch partner"
" info for vty-server@%x.\n", unit_address);
return retval;
}
/* nixes the values if the partner vty went away */
hvcsd->p_unit_address = 0;
hvcsd->p_partition_ID = 0;
list_for_each_entry(pi, &head, node)
hvcs_set_pi(pi, hvcsd);
hvcs_free_partner_info(&head);
return 0;
}
/*
* This function is executed by the driver "rescan" sysfs entry. It shouldn't
* be executed elsewhere, in order to prevent deadlock issues.
*/
static int hvcs_rescan_devices_list(void)
{
struct hvcs_struct *hvcsd;
unsigned long flags;
spin_lock(&hvcs_structs_lock);
list_for_each_entry(hvcsd, &hvcs_structs, next) {
spin_lock_irqsave(&hvcsd->lock, flags);
hvcs_get_pi(hvcsd);
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
spin_unlock(&hvcs_structs_lock);
return 0;
}
/*
* Farm this off into its own function because it could be more complex once
* multiple partners support is added. This function should be called with
* the hvcsd->lock held.
*/
static int hvcs_has_pi(struct hvcs_struct *hvcsd)
{
if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
return 0;
return 1;
}
/*
* NOTE: It is possible that the super admin removed a partner vty and then
* added a different vty as the new partner.
*
* This function must be called with the hvcsd->lock held.
*/
static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
{
int retval;
unsigned int unit_address = hvcsd->vdev->unit_address;
/*
* If there wasn't any pi when the device was added it doesn't meant
* there isn't any now. This driver isn't notified when a new partner
* vty is added to a vty-server so we discover changes on our own.
* Please see comments in hvcs_register_connection() for justification
* of this bizarre code.
*/
retval = hvcs_register_connection(unit_address,
hvcsd->p_partition_ID,
hvcsd->p_unit_address);
if (!retval) {
hvcsd->connected = 1;
return 0;
} else if (retval != -EINVAL)
return retval;
/*
* As per the spec re-get the pi and try again if -EINVAL after the
* first connection attempt.
*/
if (hvcs_get_pi(hvcsd))
return -ENOMEM;
if (!hvcs_has_pi(hvcsd))
return -ENODEV;
retval = hvcs_register_connection(unit_address,
hvcsd->p_partition_ID,
hvcsd->p_unit_address);
if (retval != -EINVAL) {
hvcsd->connected = 1;
return retval;
}
/*
* EBUSY is the most likely scenario though the vty could have been
* removed or there really could be an hcall error due to the parameter
* data but thanks to ambiguous firmware return codes we can't really
* tell.
*/
printk(KERN_INFO "HVCS: vty-server or partner"
" vty is busy. Try again later.\n");
return -EBUSY;
}
/* This function must be called with the hvcsd->lock held */
static void hvcs_partner_free(struct hvcs_struct *hvcsd)
{
int retval;
do {
retval = hvcs_free_connection(hvcsd->vdev->unit_address);
} while (retval == -EBUSY);
hvcsd->connected = 0;
}
/* This helper function must be called WITHOUT the hvcsd->lock held */
static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
unsigned int irq, struct vio_dev *vdev)
{
unsigned long flags;
int rc;
/*
* It is possible that the vty-server was removed between the time that
* the conn was registered and now.
*/
if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
IRQF_DISABLED, "ibmhvcs", hvcsd))) {
/*
* It is possible the vty-server was removed after the irq was
* requested but before we have time to enable interrupts.
*/
if (vio_enable_interrupts(vdev) == H_SUCCESS)
return 0;
else {
printk(KERN_ERR "HVCS: int enable failed for"
" vty-server@%X.\n", unit_address);
free_irq(irq, hvcsd);
}
} else
printk(KERN_ERR "HVCS: irq req failed for"
" vty-server@%X.\n", unit_address);
spin_lock_irqsave(&hvcsd->lock, flags);
hvcs_partner_free(hvcsd);
spin_unlock_irqrestore(&hvcsd->lock, flags);
return rc;
}
/*
* This always increments the kref ref count if the call is successful.
* Please remember to dec when you are done with the instance.
*
* NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
* calling this function or you will get deadlock.
*/
static struct hvcs_struct *hvcs_get_by_index(int index)
{
struct hvcs_struct *hvcsd = NULL;
unsigned long flags;
spin_lock(&hvcs_structs_lock);
/* We can immediately discard OOB requests */
if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
list_for_each_entry(hvcsd, &hvcs_structs, next) {
spin_lock_irqsave(&hvcsd->lock, flags);
if (hvcsd->index == index) {
kref_get(&hvcsd->kref);
spin_unlock_irqrestore(&hvcsd->lock, flags);
spin_unlock(&hvcs_structs_lock);
return hvcsd;
}
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
hvcsd = NULL;
}
spin_unlock(&hvcs_structs_lock);
return hvcsd;
}
/*
* This is invoked via the tty_open interface when a user app connects to the
* /dev node.
*/
static int hvcs_open(struct tty_struct *tty, struct file *filp)
{
struct hvcs_struct *hvcsd;
int rc, retval = 0;
unsigned long flags;
unsigned int irq;
struct vio_dev *vdev;
unsigned long unit_address;
if (tty->driver_data)
goto fast_open;
/*
* Is there a vty-server that shares the same index?
* This function increments the kref index.
*/
if (!(hvcsd = hvcs_get_by_index(tty->index))) {
printk(KERN_WARNING "HVCS: open failed, no device associated"
" with tty->index %d.\n", tty->index);
return -ENODEV;
}
spin_lock_irqsave(&hvcsd->lock, flags);
if (hvcsd->connected == 0)
if ((retval = hvcs_partner_connect(hvcsd)))
goto error_release;
hvcsd->open_count = 1;
hvcsd->tty = tty;
tty->driver_data = hvcsd;
memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
/*
* Save these in the spinlock for the enable operations that need them
* outside of the spinlock.
*/
irq = hvcsd->vdev->irq;
vdev = hvcsd->vdev;
unit_address = hvcsd->vdev->unit_address;
hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);
/*
* This must be done outside of the spinlock because it requests irqs
* and will grab the spinlock and free the connection if it fails.
*/
if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
kref_put(&hvcsd->kref, destroy_hvcs_struct);
printk(KERN_WARNING "HVCS: enable device failed.\n");
return rc;
}
goto open_success;
fast_open:
hvcsd = tty->driver_data;
spin_lock_irqsave(&hvcsd->lock, flags);
kref_get(&hvcsd->kref);
hvcsd->open_count++;
hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);
open_success:
hvcs_kick();
printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
hvcsd->vdev->unit_address );
return 0;
error_release:
spin_unlock_irqrestore(&hvcsd->lock, flags);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
printk(KERN_WARNING "HVCS: partner connect failed.\n");
return retval;
}
static void hvcs_close(struct tty_struct *tty, struct file *filp)
{
struct hvcs_struct *hvcsd;
unsigned long flags;
int irq = NO_IRQ;
/*
* Is someone trying to close the file associated with this device after
* we have hung up? If so tty->driver_data wouldn't be valid.
*/
if (tty_hung_up_p(filp))
return;
/*
* No driver_data means that this close was probably issued after a
* failed hvcs_open by the tty layer's release_dev() api and we can just
* exit cleanly.
*/
if (!tty->driver_data)
return;
hvcsd = tty->driver_data;
spin_lock_irqsave(&hvcsd->lock, flags);
if (--hvcsd->open_count == 0) {
vio_disable_interrupts(hvcsd->vdev);
/*
* NULL this early so that the kernel_thread doesn't try to
* execute any operations on the TTY even though it is obligated
* to deliver any pending I/O to the hypervisor.
*/
hvcsd->tty = NULL;
irq = hvcsd->vdev->irq;
spin_unlock_irqrestore(&hvcsd->lock, flags);
tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
/*
* This line is important because it tells hvcs_open that this
* device needs to be re-configured the next time hvcs_open is
* called.
*/
tty->driver_data = NULL;
free_irq(irq, hvcsd);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
return;
} else if (hvcsd->open_count < 0) {
printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
" is missmanaged.\n",
hvcsd->vdev->unit_address, hvcsd->open_count);
}
spin_unlock_irqrestore(&hvcsd->lock, flags);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
}
static void hvcs_hangup(struct tty_struct * tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned long flags;
int temp_open_count;
int irq = NO_IRQ;
spin_lock_irqsave(&hvcsd->lock, flags);
/* Preserve this so that we know how many kref refs to put */
temp_open_count = hvcsd->open_count;
/*
* Don't kref put inside the spinlock because the destruction
* callback may use the spinlock and it may get called before the
* spinlock has been released.
*/
vio_disable_interrupts(hvcsd->vdev);
hvcsd->todo_mask = 0;
/* I don't think the tty needs the hvcs_struct pointer after a hangup */
hvcsd->tty->driver_data = NULL;
hvcsd->tty = NULL;
hvcsd->open_count = 0;
/* This will drop any buffered data on the floor which is OK in a hangup
* scenario. */
memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
hvcsd->chars_in_buffer = 0;
irq = hvcsd->vdev->irq;
spin_unlock_irqrestore(&hvcsd->lock, flags);
free_irq(irq, hvcsd);
/*
* We need to kref_put() for every open_count we have since the
* tty_hangup() function doesn't invoke a close per open connection on a
* non-console device.
*/
while(temp_open_count) {
--temp_open_count;
/*
* The final put will trigger destruction of the hvcs_struct.
* NOTE: If this hangup was signaled from user space then the
* final put will never happen.
*/
kref_put(&hvcsd->kref, destroy_hvcs_struct);
}
}
/*
* NOTE: This is almost always from_user since user level apps interact with the
* /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
* hvcs_remove (which removes the target device and executes tty_hangup()) that
* tty_hangup will allow hvcs_write time to complete execution before it
* terminates our device.
*/
static int hvcs_write(struct tty_struct *tty,
const unsigned char *buf, int count)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned int unit_address;
const unsigned char *charbuf;
unsigned long flags;
int total_sent = 0;
int tosend = 0;
int result = 0;
/*
* If they don't check the return code off of their open they may
* attempt this even if there is no connected device.
*/
if (!hvcsd)
return -ENODEV;
/* Reasonable size to prevent user level flooding */
if (count > HVCS_MAX_FROM_USER) {
printk(KERN_WARNING "HVCS write: count being truncated to"
" HVCS_MAX_FROM_USER.\n");
count = HVCS_MAX_FROM_USER;
}
charbuf = buf;
spin_lock_irqsave(&hvcsd->lock, flags);
/*
* Somehow an open succedded but the device was removed or the
* connection terminated between the vty-server and partner vty during
* the middle of a write operation? This is a crummy place to do this
* but we want to keep it all in the spinlock.
*/
if (hvcsd->open_count <= 0) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
return -ENODEV;
}
unit_address = hvcsd->vdev->unit_address;
while (count > 0) {
tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
/*
* No more space, this probably means that the last call to
* hvcs_write() didn't succeed and the buffer was filled up.
*/
if (!tosend)
break;
memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
&charbuf[total_sent],
tosend);
hvcsd->chars_in_buffer += tosend;
result = 0;
/*
* If this is true then we don't want to try writing to the
* hypervisor because that is the kernel_threads job now. We'll
* just add to the buffer.
*/
if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
/* won't send partial writes */
result = hvc_put_chars(unit_address,
&hvcsd->buffer[0],
hvcsd->chars_in_buffer);
/*
* Since we know we have enough room in hvcsd->buffer for
* tosend we record that it was sent regardless of whether the
* hypervisor actually took it because we have it buffered.
*/
total_sent+=tosend;
count-=tosend;
if (result == 0) {
hvcsd->todo_mask |= HVCS_TRY_WRITE;
hvcs_kick();
break;
}
hvcsd->chars_in_buffer = 0;
/*
* Test after the chars_in_buffer reset otherwise this could
* deadlock our writes if hvc_put_chars fails.
*/
if (result < 0)
break;
}
spin_unlock_irqrestore(&hvcsd->lock, flags);
if (result == -1)
return -EIO;
else
return total_sent;
}
/*
* This is really asking how much can we guarentee that we can send or that we
* absolutely WILL BUFFER if we can't send it. This driver MUST honor the
* return value, hence the reason for hvcs_struct buffering.
*/
static int hvcs_write_room(struct tty_struct *tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
if (!hvcsd || hvcsd->open_count <= 0)
return 0;
return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
}
static int hvcs_chars_in_buffer(struct tty_struct *tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
return hvcsd->chars_in_buffer;
}
static const struct tty_operations hvcs_ops = {
.open = hvcs_open,
.close = hvcs_close,
.hangup = hvcs_hangup,
.write = hvcs_write,
.write_room = hvcs_write_room,
.chars_in_buffer = hvcs_chars_in_buffer,
.unthrottle = hvcs_unthrottle,
.throttle = hvcs_throttle,
};
static int hvcs_alloc_index_list(int n)
{
int i;
hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
if (!hvcs_index_list)
return -ENOMEM;
hvcs_index_count = n;
for (i = 0; i < hvcs_index_count; i++)
hvcs_index_list[i] = -1;
return 0;
}
static void hvcs_free_index_list(void)
{
/* Paranoia check to be thorough. */
kfree(hvcs_index_list);
hvcs_index_list = NULL;
hvcs_index_count = 0;
}
static int __init hvcs_module_init(void)
{
int rc;
int num_ttys_to_alloc;
printk(KERN_INFO "Initializing %s\n", hvcs_driver_string);
/* Has the user specified an overload with an insmod param? */
if (hvcs_parm_num_devs <= 0 ||
(hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
} else
num_ttys_to_alloc = hvcs_parm_num_devs;
hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
if (!hvcs_tty_driver)
return -ENOMEM;
if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
rc = -ENOMEM;
goto index_fail;
}
hvcs_tty_driver->owner = THIS_MODULE;
hvcs_tty_driver->driver_name = hvcs_driver_name;
hvcs_tty_driver->name = hvcs_device_node;
/*
* We'll let the system assign us a major number, indicated by leaving
* it blank.
*/
hvcs_tty_driver->minor_start = HVCS_MINOR_START;
hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
/*
* We role our own so that we DONT ECHO. We can't echo because the
* device we are connecting to already echoes by default and this would
* throw us into a horrible recursive echo-echo-echo loop.
*/
hvcs_tty_driver->init_termios = hvcs_tty_termios;
hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
tty_set_operations(hvcs_tty_driver, &hvcs_ops);
/*
* The following call will result in sysfs entries that denote the
* dynamically assigned major and minor numbers for our devices.
*/
if (tty_register_driver(hvcs_tty_driver)) {
printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
rc = -EIO;
goto register_fail;
}
hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!hvcs_pi_buff) {
rc = -ENOMEM;
goto buff_alloc_fail;
}
hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
if (IS_ERR(hvcs_task)) {
printk(KERN_ERR "HVCS: khvcsd creation failed. Driver not loaded.\n");
rc = -EIO;
goto kthread_fail;
}
rc = vio_register_driver(&hvcs_vio_driver);
if (rc) {
printk(KERN_ERR "HVCS: can't register vio driver\n");
goto vio_fail;
}
/*
* This needs to be done AFTER the vio_register_driver() call or else
* the kobjects won't be initialized properly.
*/
rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
if (rc) {
printk(KERN_ERR "HVCS: sysfs attr create failed\n");
goto attr_fail;
}
printk(KERN_INFO "HVCS: driver module inserted.\n");
return 0;
attr_fail:
vio_unregister_driver(&hvcs_vio_driver);
vio_fail:
kthread_stop(hvcs_task);
kthread_fail:
kfree(hvcs_pi_buff);
buff_alloc_fail:
tty_unregister_driver(hvcs_tty_driver);
register_fail:
hvcs_free_index_list();
index_fail:
put_tty_driver(hvcs_tty_driver);
hvcs_tty_driver = NULL;
return rc;
}
static void __exit hvcs_module_exit(void)
{
/*
* This driver receives hvcs_remove callbacks for each device upon
* module removal.
*/
/*
* This synchronous operation will wake the khvcsd kthread if it is
* asleep and will return when khvcsd has terminated.
*/
kthread_stop(hvcs_task);
spin_lock(&hvcs_pi_lock);
kfree(hvcs_pi_buff);
hvcs_pi_buff = NULL;
spin_unlock(&hvcs_pi_lock);
driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
vio_unregister_driver(&hvcs_vio_driver);
tty_unregister_driver(hvcs_tty_driver);
hvcs_free_index_list();
put_tty_driver(hvcs_tty_driver);
printk(KERN_INFO "HVCS: driver module removed.\n");
}
module_init(hvcs_module_init);
module_exit(hvcs_module_exit);
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