// SPDX-License-Identifier: GPL-2.0+
/*
* IBM eServer Hypervisor Virtual Console Server Device Driver
* Copyright (C) 2003, 2004 IBM Corp.
* Ryan S. Arnold (rsa@us.ibm.com)
*
* 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.rst.
*/
#include <linux/device.h>
#include <linux/init.h>
#include <linux/completion.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/slab.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 <linux/uaccess.h>
#include <linux/termios_internal.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 similarly 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 const 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";
/* 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 {
struct tty_port port;
spinlock_t lock;
/*
* This index identifies this hvcs device as the complement to a
* specific tty index.
*/
unsigned int index;
/*
* 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 is valid before a tty is connected and
* stays valid after the tty is disconnected. These shouldn't be
* whacked until the kobject refcount reaches zero though some entries
* may be changed via sysfs initiatives.
*/
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;
struct completion *destroyed;
};
static LIST_HEAD(hvcs_structs);
static DEFINE_SPINLOCK(hvcs_structs_lock);
static DEFINE_MUTEX(hvcs_init_mutex);
static int hvcs_get_pi(struct hvcs_struct *hvcsd);
static int hvcs_rescan_devices_list(void);
static void hvcs_partner_free(struct hvcs_struct *hvcsd);
static int hvcs_initialize(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 dev_get_drvdata(&viod->dev);
}
/* 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->port.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_dev_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,
};
ATTRIBUTE_GROUPS(hvcs_dev);
static ssize_t 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 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_RW(rescan);
static struct attribute *hvcs_attrs[] = {
&driver_attr_rescan.attr,
NULL,
};
ATTRIBUTE_GROUPS(hvcs);
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->port.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 committed 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->port.tty;
hvcs_try_write(hvcsd);
if (!tty || tty_throttled(tty)) {
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(&hvcsd->port, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
got = hvc_get_chars(unit_address,
&buf[0],
HVCS_BUFF_LEN);
tty_insert_flip_string(&hvcsd->port, 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 -- FIXME :js: it is not! */
if (got)
tty_flip_buffer_push(&hvcsd->port);
else {
/* 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 const struct vio_device_id hvcs_driver_table[] = {
{"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;
}
static void hvcs_destruct_port(struct tty_port *p)
{
struct hvcs_struct *hvcsd = container_of(p, struct hvcs_struct, port);
struct vio_dev *vdev;
struct completion *comp;
unsigned long flags;
spin_lock(&hvcs_structs_lock);
spin_lock_irqsave(&hvcsd->lock, flags);
comp = hvcsd->destroyed;
/* 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;
hvcsd->destroyed = NULL;
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);
kfree(hvcsd);
if (comp)
complete(comp);
}
static const struct tty_port_operations hvcs_port_ops = {
.destruct = hvcs_destruct_port,
};
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 hvcs_probe(
struct vio_dev *dev,
const struct vio_device_id *id)
{
struct hvcs_struct *hvcsd;
int index, rc;
if (!dev || !id) {
printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
return -EPERM;
}
/* Make sure we are properly initialized */
rc = hvcs_initialize();
if (rc) {
pr_err("HVCS: Failed to initialize core driver.\n");
return rc;
}
/* 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;
tty_port_init(&hvcsd->port);
hvcsd->port.ops = &hvcs_port_ops;
spin_lock_init(&hvcsd->lock);
hvcsd->vdev = dev;
dev_set_drvdata(&dev->dev, 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);
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 void hvcs_remove(struct vio_dev *dev)
{
struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
DECLARE_COMPLETION_ONSTACK(comp);
unsigned long flags;
struct tty_struct *tty;
/* By this time the vty-server won't be getting any more interrupts */
spin_lock_irqsave(&hvcsd->lock, flags);
hvcsd->destroyed = ∁
tty = tty_port_tty_get(&hvcsd->port);
spin_unlock_irqrestore(&hvcsd->lock, flags);
/*
* The tty should always be valid at this time unless a
* simultaneous tty close already cleaned up the hvcs_struct.
*/
if (tty) {
tty_vhangup(tty);
tty_kref_put(tty);
}
tty_port_put(&hvcsd->port);
wait_for_completion(&comp);
printk(KERN_INFO "HVCS: vty-server@%X removed from the"
" vio bus.\n", dev->unit_address);
};
static struct vio_driver hvcs_vio_driver = {
.id_table = hvcs_driver_table,
.probe = hvcs_probe,
.remove = hvcs_remove,
.name = hvcs_driver_name,
.driver = {
.groups = hvcs_groups,
.dev_groups = hvcs_dev_groups,
},
};
/* Only called from hvcs_get_pi please */
static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
{
hvcsd->p_unit_address = pi->unit_address;
hvcsd->p_partition_ID = pi->partition_ID;
/* copy the null-term char too */
strscpy(hvcsd->p_location_code, pi->location_code,
sizeof(hvcsd->p_location_code));
}
/*
* 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.
*/
rc = request_irq(irq, &hvcs_handle_interrupt, 0, "ibmhvcs", hvcsd);
if (!rc) {
/*
* 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;
unsigned long flags;
spin_lock(&hvcs_structs_lock);
list_for_each_entry(hvcsd, &hvcs_structs, next) {
spin_lock_irqsave(&hvcsd->lock, flags);
if (hvcsd->index == index) {
tty_port_get(&hvcsd->port);
spin_unlock_irqrestore(&hvcsd->lock, flags);
spin_unlock(&hvcs_structs_lock);
return hvcsd;
}
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
spin_unlock(&hvcs_structs_lock);
return NULL;
}
static int hvcs_install(struct tty_driver *driver, struct tty_struct *tty)
{
struct hvcs_struct *hvcsd;
struct vio_dev *vdev;
unsigned long unit_address, flags;
unsigned int irq;
int retval;
/*
* Is there a vty-server that shares the same index?
* This function increments the kref index.
*/
hvcsd = hvcs_get_by_index(tty->index);
if (!hvcsd) {
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) {
retval = hvcs_partner_connect(hvcsd);
if (retval) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
printk(KERN_WARNING "HVCS: partner connect failed.\n");
goto err_put;
}
}
hvcsd->port.count = 0;
hvcsd->port.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.
*/
retval = hvcs_enable_device(hvcsd, unit_address, irq, vdev);
if (retval) {
printk(KERN_WARNING "HVCS: enable device failed.\n");
goto err_put;
}
retval = tty_port_install(&hvcsd->port, driver, tty);
if (retval)
goto err_irq;
return 0;
err_irq:
spin_lock_irqsave(&hvcsd->lock, flags);
vio_disable_interrupts(hvcsd->vdev);
spin_unlock_irqrestore(&hvcsd->lock, flags);
free_irq(irq, hvcsd);
err_put:
tty_port_put(&hvcsd->port);
return retval;
}
/*
* 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 = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&hvcsd->lock, flags);
hvcsd->port.count++;
hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);
hvcs_kick();
printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
hvcsd->vdev->unit_address );
return 0;
}
static void hvcs_close(struct tty_struct *tty, struct file *filp)
{
struct hvcs_struct *hvcsd;
unsigned long flags;
int 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->port.count == 0) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
return;
} else if (--hvcsd->port.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->port.tty = NULL;
irq = hvcsd->vdev->irq;
spin_unlock_irqrestore(&hvcsd->lock, flags);
tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
free_irq(irq, hvcsd);
return;
} else if (hvcsd->port.count < 0) {
printk(KERN_ERR "HVCS: vty-server@%X open_count: %d is mismanaged.\n",
hvcsd->vdev->unit_address, hvcsd->port.count);
}
spin_unlock_irqrestore(&hvcsd->lock, flags);
}
static void hvcs_cleanup(struct tty_struct * tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
/*
* 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;
tty_port_put(&hvcsd->port);
}
static void hvcs_hangup(struct tty_struct * tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned long flags;
int irq;
spin_lock_irqsave(&hvcsd->lock, flags);
/*
* 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;
hvcsd->port.tty = NULL;
hvcsd->port.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);
}
/*
* 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 ssize_t hvcs_write(struct tty_struct *tty, const u8 *buf, size_t count)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned int unit_address;
const unsigned char *charbuf;
unsigned long flags;
size_t total_sent = 0;
size_t 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 succeeded 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->port.count <= 0) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
return -ENODEV;
}
unit_address = hvcsd->vdev->unit_address;
while (count > 0) {
tosend = min_t(size_t, 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 guarantee 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 unsigned int hvcs_write_room(struct tty_struct *tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
if (!hvcsd || hvcsd->port.count <= 0)
return 0;
return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
}
static unsigned 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 = {
.install = hvcs_install,
.open = hvcs_open,
.close = hvcs_close,
.cleanup = hvcs_cleanup,
.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_array(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 hvcs_initialize(void)
{
int rc, num_ttys_to_alloc;
mutex_lock(&hvcs_init_mutex);
if (hvcs_task) {
mutex_unlock(&hvcs_init_mutex);
return 0;
}
/* 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 = tty_alloc_driver(num_ttys_to_alloc,
TTY_DRIVER_REAL_RAW);
if (IS_ERR(hvcs_tty_driver)) {
mutex_unlock(&hvcs_init_mutex);
return PTR_ERR(hvcs_tty_driver);
}
if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
rc = -ENOMEM;
goto index_fail;
}
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;
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 = (unsigned long *) __get_free_page(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.\n");
rc = -EIO;
goto kthread_fail;
}
mutex_unlock(&hvcs_init_mutex);
return 0;
kthread_fail:
free_page((unsigned long)hvcs_pi_buff);
buff_alloc_fail:
tty_unregister_driver(hvcs_tty_driver);
register_fail:
hvcs_free_index_list();
index_fail:
tty_driver_kref_put(hvcs_tty_driver);
hvcs_tty_driver = NULL;
mutex_unlock(&hvcs_init_mutex);
return rc;
}
static int __init hvcs_module_init(void)
{
int rc = vio_register_driver(&hvcs_vio_driver);
if (rc) {
printk(KERN_ERR "HVCS: can't register vio driver\n");
return rc;
}
pr_info("HVCS: Driver registered.\n");
return 0;
}
static void __exit hvcs_module_exit(void)
{
/*
* This driver receives hvcs_remove callbacks for each device upon
* module removal.
*/
vio_unregister_driver(&hvcs_vio_driver);
if (!hvcs_task)
return;
/*
* 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);
free_page((unsigned long)hvcs_pi_buff);
hvcs_pi_buff = NULL;
spin_unlock(&hvcs_pi_lock);
tty_unregister_driver(hvcs_tty_driver);
hvcs_free_index_list();
tty_driver_kref_put(hvcs_tty_driver);
printk(KERN_INFO "HVCS: driver module removed.\n");
}
module_init(hvcs_module_init);
module_exit(hvcs_module_exit);