v4.19.13 snapshot.
diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
new file mode 100644
index 0000000..cb4db1b
--- /dev/null
+++ b/drivers/tty/hvc/hvcs.c
@@ -0,0 +1,1602 @@
+// 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.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/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 <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";
+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 {
+ 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;
+};
+
+static LIST_HEAD(hvcs_structs);
+static DEFINE_SPINLOCK(hvcs_structs_lock);
+static DEFINE_MUTEX(hvcs_init_mutex);
+
+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 hvcs_probe(struct vio_dev *dev,
+ const struct vio_device_id *id);
+static int hvcs_remove(struct vio_dev *dev);
+static int __init hvcs_module_init(void);
+static void __exit hvcs_module_exit(void);
+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_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 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 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 because tty->low_latency == 1 */
+ if(got)
+ tty_flip_buffer_push(&hvcsd->port);
+
+ 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 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;
+ 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 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;
+ int retval;
+
+ 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);
+
+ 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 hvcs_remove(struct vio_dev *dev)
+{
+ struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
+ 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->port.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.
+ */
+ tty_port_put(&hvcsd->port);
+
+ /*
+ * 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,
+ .name = hvcs_driver_name,
+};
+
+/* 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 */
+ strlcpy(&hvcsd->p_location_code[0],
+ &pi->location_code[0], 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) {
+
+ 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);
+
+ /*
+ * 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);
+ 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;
+
+ tty_port_put(&hvcsd->port);
+}
+
+static void hvcs_hangup(struct tty_struct * tty)
+{
+ struct hvcs_struct *hvcsd = tty->driver_data;
+ unsigned long flags;
+ int temp_open_count;
+ int irq;
+
+ spin_lock_irqsave(&hvcsd->lock, flags);
+ /* Preserve this so that we know how many kref refs to put */
+ temp_open_count = hvcsd->port.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 */
+ tty->driver_data = NULL;
+ 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);
+
+ /*
+ * 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.
+ */
+ tty_port_put(&hvcsd->port);
+ }
+}
+
+/*
+ * 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 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(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 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 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 = alloc_tty_driver(num_ttys_to_alloc);
+ if (!hvcs_tty_driver) {
+ mutex_unlock(&hvcs_init_mutex);
+ return -ENOMEM;
+ }
+
+ 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;
+ 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 = (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:
+ put_tty_driver(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");
+
+ /* 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)
+ pr_warn("HVCS: Failed to create rescan file (err %d)\n", rc);
+
+ 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);
+
+ driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
+
+ 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);