Root/drivers/tty/hvc/hvcs.c

1/*
2 * IBM eServer Hypervisor Virtual Console Server Device Driver
3 * Copyright (C) 2003, 2004 IBM Corp.
4 * Ryan S. Arnold (rsa@us.ibm.com)
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 *
20 * Author(s) : Ryan S. Arnold <rsa@us.ibm.com>
21 *
22 * This is the device driver for the IBM Hypervisor Virtual Console Server,
23 * "hvcs". The IBM hvcs provides a tty driver interface to allow Linux
24 * user space applications access to the system consoles of logically
25 * partitioned operating systems, e.g. Linux, running on the same partitioned
26 * Power5 ppc64 system. Physical hardware consoles per partition are not
27 * practical on this hardware so system consoles are accessed by this driver
28 * using inter-partition firmware interfaces to virtual terminal devices.
29 *
30 * A vty is known to the HMC as a "virtual serial server adapter". It is a
31 * virtual terminal device that is created by firmware upon partition creation
32 * to act as a partitioned OS's console device.
33 *
34 * Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
35 * Linux system upon their creation by the HMC or their exposure during boot.
36 * The non-user interactive backend of this driver is implemented as a vio
37 * device driver so that it can receive notification of vty-server lifetimes
38 * after it registers with the vio bus to handle vty-server probe and remove
39 * callbacks.
40 *
41 * Many vty-servers can be configured to connect to one vty, but a vty can
42 * only be actively connected to by a single vty-server, in any manner, at one
43 * time. If the HMC is currently hosting the console for a target Linux
44 * partition; attempts to open the tty device to the partition's console using
45 * the hvcs on any partition will return -EBUSY with every open attempt until
46 * the HMC frees the connection between its vty-server and the desired
47 * partition's vty device. Conversely, a vty-server may only be connected to
48 * a single vty at one time even though it may have several configured vty
49 * partner possibilities.
50 *
51 * Firmware does not provide notification of vty partner changes to this
52 * driver. This means that an HMC Super Admin may add or remove partner vtys
53 * from a vty-server's partner list but the changes will not be signaled to
54 * the vty-server. Firmware only notifies the driver when a vty-server is
55 * added or removed from the system. To compensate for this deficiency, this
56 * driver implements a sysfs update attribute which provides a method for
57 * rescanning partner information upon a user's request.
58 *
59 * Each vty-server, prior to being exposed to this driver is reference counted
60 * using the 2.6 Linux kernel kref construct.
61 *
62 * For direction on installation and usage of this driver please reference
63 * Documentation/powerpc/hvcs.txt.
64 */
65
66#include <linux/device.h>
67#include <linux/init.h>
68#include <linux/interrupt.h>
69#include <linux/kernel.h>
70#include <linux/kref.h>
71#include <linux/kthread.h>
72#include <linux/list.h>
73#include <linux/major.h>
74#include <linux/module.h>
75#include <linux/moduleparam.h>
76#include <linux/sched.h>
77#include <linux/slab.h>
78#include <linux/spinlock.h>
79#include <linux/stat.h>
80#include <linux/tty.h>
81#include <linux/tty_flip.h>
82#include <asm/hvconsole.h>
83#include <asm/hvcserver.h>
84#include <asm/uaccess.h>
85#include <asm/vio.h>
86
87/*
88 * 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
89 * Removed braces around single statements following conditionals. Removed '=
90 * 0' after static int declarations since these default to zero. Removed
91 * list_for_each_safe() and replaced with list_for_each_entry() in
92 * hvcs_get_by_index(). The 'safe' version is un-needed now that the driver is
93 * using spinlocks. Changed spin_lock_irqsave() to spin_lock() when locking
94 * hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
95 * handler. Initialized hvcs_structs_lock and hvcs_pi_lock to
96 * SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
97 * Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
98 * list traversals from a deletion. Removed '= NULL' from pointer declaration
99 * statements since they are initialized NULL by default. Removed wmb()
100 * instances from hvcs_try_write(). They probably aren't needed with locking in
101 * place. Added check and cleanup for hvcs_pi_buff = kmalloc() in
102 * hvcs_module_init(). Exposed hvcs_struct.index via a sysfs attribute so that
103 * the coupling between /dev/hvcs* and a vty-server can be automatically
104 * determined. Moved kobject_put() in hvcs_open outside of the
105 * spin_unlock_irqrestore().
106 *
107 * 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
108 * align with how the tty layer always assigns the lowest index available. This
109 * change resulted in a list of ints that denotes which indexes are available.
110 * Device additions and removals use the new hvcs_get_index() and
111 * hvcs_return_index() helper functions. The list is created with
112 * hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
113 * Without these fixes hotplug vty-server adapter support goes crazy with this
114 * driver if the user removes a vty-server adapter. Moved free_irq() outside of
115 * the hvcs_final_close() function in order to get it out of the spinlock.
116 * Rearranged hvcs_close(). Cleaned up some printks and did some housekeeping
117 * on the changelog. Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
118 * arch/powerepc/include/asm/hvcserver.h
119 *
120 * 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
121 * prevent possible lockup with realtime scheduling as similarly pointed out by
122 * akpm in hvc_console. Changed resulted in the removal of hvcs_final_close()
123 * to reorder cleanup operations and prevent discarding of pending data during
124 * an hvcs_close(). Removed spinlock protection of hvcs_struct data members in
125 * hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
126 */
127
128#define HVCS_DRIVER_VERSION "1.3.3"
129
130MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
131MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
132MODULE_LICENSE("GPL");
133MODULE_VERSION(HVCS_DRIVER_VERSION);
134
135/*
136 * Wait this long per iteration while trying to push buffered data to the
137 * hypervisor before allowing the tty to complete a close operation.
138 */
139#define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
140
141/*
142 * Since the Linux TTY code does not currently (2-04-2004) support dynamic
143 * addition of tty derived devices and we shouldn't allocate thousands of
144 * tty_device pointers when the number of vty-server & vty partner connections
145 * will most often be much lower than this, we'll arbitrarily allocate
146 * HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
147 * register the tty_driver. This can be overridden using an insmod parameter.
148 */
149#define HVCS_DEFAULT_SERVER_ADAPTERS 64
150
151/*
152 * The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
153 * nodes as a sanity check. Theoretically there can be over 1 Billion
154 * vty-server & vty partner connections.
155 */
156#define HVCS_MAX_SERVER_ADAPTERS 1024
157
158/*
159 * We let Linux assign us a major number and we start the minors at zero. There
160 * is no intuitive mapping between minor number and the target vty-server
161 * adapter except that each new vty-server adapter is always assigned to the
162 * smallest minor number available.
163 */
164#define HVCS_MINOR_START 0
165
166/*
167 * The hcall interface involves putting 8 chars into each of two registers.
168 * We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
169 * by casting char[16] to long[2]. It would work without __ALIGNED__, but a
170 * little (tiny) bit slower because an unaligned load is slower than aligned
171 * load.
172 */
173#define __ALIGNED__ __attribute__((__aligned__(8)))
174
175/*
176 * How much data can firmware send with each hvc_put_chars()? Maybe this
177 * should be moved into an architecture specific area.
178 */
179#define HVCS_BUFF_LEN 16
180
181/*
182 * This is the maximum amount of data we'll let the user send us (hvcs_write) at
183 * once in a chunk as a sanity check.
184 */
185#define HVCS_MAX_FROM_USER 4096
186
187/*
188 * Be careful when adding flags to this line discipline. Don't add anything
189 * that will cause echoing or we'll go into recursive loop echoing chars back
190 * and forth with the console drivers.
191 */
192static struct ktermios hvcs_tty_termios = {
193    .c_iflag = IGNBRK | IGNPAR,
194    .c_oflag = OPOST,
195    .c_cflag = B38400 | CS8 | CREAD | HUPCL,
196    .c_cc = INIT_C_CC,
197    .c_ispeed = 38400,
198    .c_ospeed = 38400
199};
200
201/*
202 * This value is used to take the place of a command line parameter when the
203 * module is inserted. It starts as -1 and stays as such if the user doesn't
204 * specify a module insmod parameter. If they DO specify one then it is set to
205 * the value of the integer passed in.
206 */
207static int hvcs_parm_num_devs = -1;
208module_param(hvcs_parm_num_devs, int, 0);
209
210static const char hvcs_driver_name[] = "hvcs";
211static const char hvcs_device_node[] = "hvcs";
212static const char hvcs_driver_string[]
213    = "IBM hvcs (Hypervisor Virtual Console Server) Driver";
214
215/* Status of partner info rescan triggered via sysfs. */
216static int hvcs_rescan_status;
217
218static struct tty_driver *hvcs_tty_driver;
219
220/*
221 * In order to be somewhat sane this driver always associates the hvcs_struct
222 * index element with the numerically equal tty->index. This means that a
223 * hotplugged vty-server adapter will always map to the lowest index valued
224 * device node. If vty-servers were hotplug removed from the system and then
225 * new ones added the new vty-server may have the largest slot number of all
226 * the vty-server adapters in the partition but it may have the lowest dev node
227 * index of all the adapters due to the hole left by the hotplug removed
228 * adapter. There are a set of functions provided to get the lowest index for
229 * a new device as well as return the index to the list. This list is allocated
230 * with a number of elements equal to the number of device nodes requested when
231 * the module was inserted.
232 */
233static int *hvcs_index_list;
234
235/*
236 * How large is the list? This is kept for traversal since the list is
237 * dynamically created.
238 */
239static int hvcs_index_count;
240
241/*
242 * Used by the khvcsd to pick up I/O operations when the kernel_thread is
243 * already awake but potentially shifted to TASK_INTERRUPTIBLE state.
244 */
245static int hvcs_kicked;
246
247/*
248 * Use by the kthread construct for task operations like waking the sleeping
249 * thread and stopping the kthread.
250 */
251static struct task_struct *hvcs_task;
252
253/*
254 * We allocate this for the use of all of the hvcs_structs when they fetch
255 * partner info.
256 */
257static unsigned long *hvcs_pi_buff;
258
259/* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
260static DEFINE_SPINLOCK(hvcs_pi_lock);
261
262/* One vty-server per hvcs_struct */
263struct hvcs_struct {
264    struct tty_port port;
265    spinlock_t lock;
266
267    /*
268     * This index identifies this hvcs device as the complement to a
269     * specific tty index.
270     */
271    unsigned int index;
272
273    /*
274     * Used to tell the driver kernel_thread what operations need to take
275     * place upon this hvcs_struct instance.
276     */
277    int todo_mask;
278
279    /*
280     * This buffer is required so that when hvcs_write_room() reports that
281     * it can send HVCS_BUFF_LEN characters that it will buffer the full
282     * HVCS_BUFF_LEN characters if need be. This is essential for opost
283     * writes since they do not do high level buffering and expect to be
284     * able to send what the driver commits to sending buffering
285     * [e.g. tab to space conversions in n_tty.c opost()].
286     */
287    char buffer[HVCS_BUFF_LEN];
288    int chars_in_buffer;
289
290    /*
291     * Any variable below is valid before a tty is connected and
292     * stays valid after the tty is disconnected. These shouldn't be
293     * whacked until the kobject refcount reaches zero though some entries
294     * may be changed via sysfs initiatives.
295     */
296    int connected; /* is the vty-server currently connected to a vty? */
297    uint32_t p_unit_address; /* partner unit address */
298    uint32_t p_partition_ID; /* partner partition ID */
299    char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
300    struct list_head next; /* list management */
301    struct vio_dev *vdev;
302};
303
304static LIST_HEAD(hvcs_structs);
305static DEFINE_SPINLOCK(hvcs_structs_lock);
306static DEFINE_MUTEX(hvcs_init_mutex);
307
308static void hvcs_unthrottle(struct tty_struct *tty);
309static void hvcs_throttle(struct tty_struct *tty);
310static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
311
312static int hvcs_write(struct tty_struct *tty,
313        const unsigned char *buf, int count);
314static int hvcs_write_room(struct tty_struct *tty);
315static int hvcs_chars_in_buffer(struct tty_struct *tty);
316
317static int hvcs_has_pi(struct hvcs_struct *hvcsd);
318static void hvcs_set_pi(struct hvcs_partner_info *pi,
319        struct hvcs_struct *hvcsd);
320static int hvcs_get_pi(struct hvcs_struct *hvcsd);
321static int hvcs_rescan_devices_list(void);
322
323static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
324static void hvcs_partner_free(struct hvcs_struct *hvcsd);
325
326static int hvcs_enable_device(struct hvcs_struct *hvcsd,
327        uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
328
329static int hvcs_open(struct tty_struct *tty, struct file *filp);
330static void hvcs_close(struct tty_struct *tty, struct file *filp);
331static void hvcs_hangup(struct tty_struct * tty);
332
333static int hvcs_probe(struct vio_dev *dev,
334        const struct vio_device_id *id);
335static int hvcs_remove(struct vio_dev *dev);
336static int __init hvcs_module_init(void);
337static void __exit hvcs_module_exit(void);
338static int hvcs_initialize(void);
339
340#define HVCS_SCHED_READ 0x00000001
341#define HVCS_QUICK_READ 0x00000002
342#define HVCS_TRY_WRITE 0x00000004
343#define HVCS_READ_MASK (HVCS_SCHED_READ | HVCS_QUICK_READ)
344
345static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
346{
347    return dev_get_drvdata(&viod->dev);
348}
349/* The sysfs interface for the driver and devices */
350
351static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
352{
353    struct vio_dev *viod = to_vio_dev(dev);
354    struct hvcs_struct *hvcsd = from_vio_dev(viod);
355    unsigned long flags;
356    int retval;
357
358    spin_lock_irqsave(&hvcsd->lock, flags);
359    retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
360    spin_unlock_irqrestore(&hvcsd->lock, flags);
361    return retval;
362}
363static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
364
365static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
366{
367    struct vio_dev *viod = to_vio_dev(dev);
368    struct hvcs_struct *hvcsd = from_vio_dev(viod);
369    unsigned long flags;
370    int retval;
371
372    spin_lock_irqsave(&hvcsd->lock, flags);
373    retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
374    spin_unlock_irqrestore(&hvcsd->lock, flags);
375    return retval;
376}
377static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
378
379static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
380        size_t count)
381{
382    /*
383     * Don't need this feature at the present time because firmware doesn't
384     * yet support multiple partners.
385     */
386    printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
387    return -EPERM;
388}
389
390static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
391{
392    struct vio_dev *viod = to_vio_dev(dev);
393    struct hvcs_struct *hvcsd = from_vio_dev(viod);
394    unsigned long flags;
395    int retval;
396
397    spin_lock_irqsave(&hvcsd->lock, flags);
398    retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
399    spin_unlock_irqrestore(&hvcsd->lock, flags);
400    return retval;
401}
402
403static DEVICE_ATTR(current_vty,
404    S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
405
406static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
407        size_t count)
408{
409    struct vio_dev *viod = to_vio_dev(dev);
410    struct hvcs_struct *hvcsd = from_vio_dev(viod);
411    unsigned long flags;
412
413    /* writing a '0' to this sysfs entry will result in the disconnect. */
414    if (simple_strtol(buf, NULL, 0) != 0)
415        return -EINVAL;
416
417    spin_lock_irqsave(&hvcsd->lock, flags);
418
419    if (hvcsd->port.count > 0) {
420        spin_unlock_irqrestore(&hvcsd->lock, flags);
421        printk(KERN_INFO "HVCS: vterm state unchanged. "
422                "The hvcs device node is still in use.\n");
423        return -EPERM;
424    }
425
426    if (hvcsd->connected == 0) {
427        spin_unlock_irqrestore(&hvcsd->lock, flags);
428        printk(KERN_INFO "HVCS: vterm state unchanged. The"
429                " vty-server is not connected to a vty.\n");
430        return -EPERM;
431    }
432
433    hvcs_partner_free(hvcsd);
434    printk(KERN_INFO "HVCS: Closed vty-server@%X and"
435            " partner vty@%X:%d connection.\n",
436            hvcsd->vdev->unit_address,
437            hvcsd->p_unit_address,
438            (uint32_t)hvcsd->p_partition_ID);
439
440    spin_unlock_irqrestore(&hvcsd->lock, flags);
441    return count;
442}
443
444static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
445{
446    struct vio_dev *viod = to_vio_dev(dev);
447    struct hvcs_struct *hvcsd = from_vio_dev(viod);
448    unsigned long flags;
449    int retval;
450
451    spin_lock_irqsave(&hvcsd->lock, flags);
452    retval = sprintf(buf, "%d\n", hvcsd->connected);
453    spin_unlock_irqrestore(&hvcsd->lock, flags);
454    return retval;
455}
456static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
457        hvcs_vterm_state_show, hvcs_vterm_state_store);
458
459static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
460{
461    struct vio_dev *viod = to_vio_dev(dev);
462    struct hvcs_struct *hvcsd = from_vio_dev(viod);
463    unsigned long flags;
464    int retval;
465
466    spin_lock_irqsave(&hvcsd->lock, flags);
467    retval = sprintf(buf, "%d\n", hvcsd->index);
468    spin_unlock_irqrestore(&hvcsd->lock, flags);
469    return retval;
470}
471
472static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
473
474static struct attribute *hvcs_attrs[] = {
475    &dev_attr_partner_vtys.attr,
476    &dev_attr_partner_clcs.attr,
477    &dev_attr_current_vty.attr,
478    &dev_attr_vterm_state.attr,
479    &dev_attr_index.attr,
480    NULL,
481};
482
483static struct attribute_group hvcs_attr_group = {
484    .attrs = hvcs_attrs,
485};
486
487static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
488{
489    /* A 1 means it is updating, a 0 means it is done updating */
490    return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
491}
492
493static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
494        size_t count)
495{
496    if ((simple_strtol(buf, NULL, 0) != 1)
497        && (hvcs_rescan_status != 0))
498        return -EINVAL;
499
500    hvcs_rescan_status = 1;
501    printk(KERN_INFO "HVCS: rescanning partner info for all"
502        " vty-servers.\n");
503    hvcs_rescan_devices_list();
504    hvcs_rescan_status = 0;
505    return count;
506}
507
508static DRIVER_ATTR(rescan,
509    S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
510
511static void hvcs_kick(void)
512{
513    hvcs_kicked = 1;
514    wmb();
515    wake_up_process(hvcs_task);
516}
517
518static void hvcs_unthrottle(struct tty_struct *tty)
519{
520    struct hvcs_struct *hvcsd = tty->driver_data;
521    unsigned long flags;
522
523    spin_lock_irqsave(&hvcsd->lock, flags);
524    hvcsd->todo_mask |= HVCS_SCHED_READ;
525    spin_unlock_irqrestore(&hvcsd->lock, flags);
526    hvcs_kick();
527}
528
529static void hvcs_throttle(struct tty_struct *tty)
530{
531    struct hvcs_struct *hvcsd = tty->driver_data;
532    unsigned long flags;
533
534    spin_lock_irqsave(&hvcsd->lock, flags);
535    vio_disable_interrupts(hvcsd->vdev);
536    spin_unlock_irqrestore(&hvcsd->lock, flags);
537}
538
539/*
540 * If the device is being removed we don't have to worry about this interrupt
541 * handler taking any further interrupts because they are disabled which means
542 * the hvcs_struct will always be valid in this handler.
543 */
544static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
545{
546    struct hvcs_struct *hvcsd = dev_instance;
547
548    spin_lock(&hvcsd->lock);
549    vio_disable_interrupts(hvcsd->vdev);
550    hvcsd->todo_mask |= HVCS_SCHED_READ;
551    spin_unlock(&hvcsd->lock);
552    hvcs_kick();
553
554    return IRQ_HANDLED;
555}
556
557/* This function must be called with the hvcsd->lock held */
558static void hvcs_try_write(struct hvcs_struct *hvcsd)
559{
560    uint32_t unit_address = hvcsd->vdev->unit_address;
561    struct tty_struct *tty = hvcsd->port.tty;
562    int sent;
563
564    if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
565        /* won't send partial writes */
566        sent = hvc_put_chars(unit_address,
567                &hvcsd->buffer[0],
568                hvcsd->chars_in_buffer );
569        if (sent > 0) {
570            hvcsd->chars_in_buffer = 0;
571            /* wmb(); */
572            hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
573            /* wmb(); */
574
575            /*
576             * We are still obligated to deliver the data to the
577             * hypervisor even if the tty has been closed because
578             * we committed to delivering it. But don't try to wake
579             * a non-existent tty.
580             */
581            if (tty) {
582                tty_wakeup(tty);
583            }
584        }
585    }
586}
587
588static int hvcs_io(struct hvcs_struct *hvcsd)
589{
590    uint32_t unit_address;
591    struct tty_struct *tty;
592    char buf[HVCS_BUFF_LEN] __ALIGNED__;
593    unsigned long flags;
594    int got = 0;
595
596    spin_lock_irqsave(&hvcsd->lock, flags);
597
598    unit_address = hvcsd->vdev->unit_address;
599    tty = hvcsd->port.tty;
600
601    hvcs_try_write(hvcsd);
602
603    if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
604        hvcsd->todo_mask &= ~(HVCS_READ_MASK);
605        goto bail;
606    } else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
607        goto bail;
608
609    /* remove the read masks */
610    hvcsd->todo_mask &= ~(HVCS_READ_MASK);
611
612    if (tty_buffer_request_room(&hvcsd->port, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
613        got = hvc_get_chars(unit_address,
614                &buf[0],
615                HVCS_BUFF_LEN);
616        tty_insert_flip_string(&hvcsd->port, buf, got);
617    }
618
619    /* Give the TTY time to process the data we just sent. */
620    if (got)
621        hvcsd->todo_mask |= HVCS_QUICK_READ;
622
623    spin_unlock_irqrestore(&hvcsd->lock, flags);
624    /* This is synch because tty->low_latency == 1 */
625    if(got)
626        tty_flip_buffer_push(&hvcsd->port);
627
628    if (!got) {
629        /* Do this _after_ the flip_buffer_push */
630        spin_lock_irqsave(&hvcsd->lock, flags);
631        vio_enable_interrupts(hvcsd->vdev);
632        spin_unlock_irqrestore(&hvcsd->lock, flags);
633    }
634
635    return hvcsd->todo_mask;
636
637 bail:
638    spin_unlock_irqrestore(&hvcsd->lock, flags);
639    return hvcsd->todo_mask;
640}
641
642static int khvcsd(void *unused)
643{
644    struct hvcs_struct *hvcsd;
645    int hvcs_todo_mask;
646
647    __set_current_state(TASK_RUNNING);
648
649    do {
650        hvcs_todo_mask = 0;
651        hvcs_kicked = 0;
652        wmb();
653
654        spin_lock(&hvcs_structs_lock);
655        list_for_each_entry(hvcsd, &hvcs_structs, next) {
656            hvcs_todo_mask |= hvcs_io(hvcsd);
657        }
658        spin_unlock(&hvcs_structs_lock);
659
660        /*
661         * If any of the hvcs adapters want to try a write or quick read
662         * don't schedule(), yield a smidgen then execute the hvcs_io
663         * thread again for those that want the write.
664         */
665         if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
666            yield();
667            continue;
668        }
669
670        set_current_state(TASK_INTERRUPTIBLE);
671        if (!hvcs_kicked)
672            schedule();
673        __set_current_state(TASK_RUNNING);
674    } while (!kthread_should_stop());
675
676    return 0;
677}
678
679static struct vio_device_id hvcs_driver_table[] = {
680    {"serial-server", "hvterm2"},
681    { "", "" }
682};
683MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
684
685static void hvcs_return_index(int index)
686{
687    /* Paranoia check */
688    if (!hvcs_index_list)
689        return;
690    if (index < 0 || index >= hvcs_index_count)
691        return;
692    if (hvcs_index_list[index] == -1)
693        return;
694    else
695        hvcs_index_list[index] = -1;
696}
697
698static void hvcs_destruct_port(struct tty_port *p)
699{
700    struct hvcs_struct *hvcsd = container_of(p, struct hvcs_struct, port);
701    struct vio_dev *vdev;
702    unsigned long flags;
703
704    spin_lock(&hvcs_structs_lock);
705    spin_lock_irqsave(&hvcsd->lock, flags);
706
707    /* the list_del poisons the pointers */
708    list_del(&(hvcsd->next));
709
710    if (hvcsd->connected == 1) {
711        hvcs_partner_free(hvcsd);
712        printk(KERN_INFO "HVCS: Closed vty-server@%X and"
713                " partner vty@%X:%d connection.\n",
714                hvcsd->vdev->unit_address,
715                hvcsd->p_unit_address,
716                (uint32_t)hvcsd->p_partition_ID);
717    }
718    printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
719            hvcsd->vdev->unit_address);
720
721    vdev = hvcsd->vdev;
722    hvcsd->vdev = NULL;
723
724    hvcsd->p_unit_address = 0;
725    hvcsd->p_partition_ID = 0;
726    hvcs_return_index(hvcsd->index);
727    memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
728
729    spin_unlock_irqrestore(&hvcsd->lock, flags);
730    spin_unlock(&hvcs_structs_lock);
731
732    sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
733
734    kfree(hvcsd);
735}
736
737static const struct tty_port_operations hvcs_port_ops = {
738    .destruct = hvcs_destruct_port,
739};
740
741static int hvcs_get_index(void)
742{
743    int i;
744    /* Paranoia check */
745    if (!hvcs_index_list) {
746        printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
747        return -EFAULT;
748    }
749    /* Find the numerically lowest first free index. */
750    for(i = 0; i < hvcs_index_count; i++) {
751        if (hvcs_index_list[i] == -1) {
752            hvcs_index_list[i] = 0;
753            return i;
754        }
755    }
756    return -1;
757}
758
759static int hvcs_probe(
760    struct vio_dev *dev,
761    const struct vio_device_id *id)
762{
763    struct hvcs_struct *hvcsd;
764    int index, rc;
765    int retval;
766
767    if (!dev || !id) {
768        printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
769        return -EPERM;
770    }
771
772    /* Make sure we are properly initialized */
773    rc = hvcs_initialize();
774    if (rc) {
775        pr_err("HVCS: Failed to initialize core driver.\n");
776        return rc;
777    }
778
779    /* early to avoid cleanup on failure */
780    index = hvcs_get_index();
781    if (index < 0) {
782        return -EFAULT;
783    }
784
785    hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
786    if (!hvcsd)
787        return -ENODEV;
788
789    tty_port_init(&hvcsd->port);
790    hvcsd->port.ops = &hvcs_port_ops;
791    spin_lock_init(&hvcsd->lock);
792
793    hvcsd->vdev = dev;
794    dev_set_drvdata(&dev->dev, hvcsd);
795
796    hvcsd->index = index;
797
798    /* hvcsd->index = ++hvcs_struct_count; */
799    hvcsd->chars_in_buffer = 0;
800    hvcsd->todo_mask = 0;
801    hvcsd->connected = 0;
802
803    /*
804     * This will populate the hvcs_struct's partner info fields for the
805     * first time.
806     */
807    if (hvcs_get_pi(hvcsd)) {
808        printk(KERN_ERR "HVCS: Failed to fetch partner"
809            " info for vty-server@%X on device probe.\n",
810            hvcsd->vdev->unit_address);
811    }
812
813    /*
814     * If a user app opens a tty that corresponds to this vty-server before
815     * the hvcs_struct has been added to the devices list then the user app
816     * will get -ENODEV.
817     */
818    spin_lock(&hvcs_structs_lock);
819    list_add_tail(&(hvcsd->next), &hvcs_structs);
820    spin_unlock(&hvcs_structs_lock);
821
822    retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
823    if (retval) {
824        printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
825               hvcsd->vdev->unit_address);
826        return retval;
827    }
828
829    printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
830
831    /*
832     * DON'T enable interrupts here because there is no user to receive the
833     * data.
834     */
835    return 0;
836}
837
838static int hvcs_remove(struct vio_dev *dev)
839{
840    struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
841    unsigned long flags;
842    struct tty_struct *tty;
843
844    if (!hvcsd)
845        return -ENODEV;
846
847    /* By this time the vty-server won't be getting any more interrupts */
848
849    spin_lock_irqsave(&hvcsd->lock, flags);
850
851    tty = hvcsd->port.tty;
852
853    spin_unlock_irqrestore(&hvcsd->lock, flags);
854
855    /*
856     * Let the last holder of this object cause it to be removed, which
857     * would probably be tty_hangup below.
858     */
859    tty_port_put(&hvcsd->port);
860
861    /*
862     * The hangup is a scheduled function which will auto chain call
863     * hvcs_hangup. The tty should always be valid at this time unless a
864     * simultaneous tty close already cleaned up the hvcs_struct.
865     */
866    if (tty)
867        tty_hangup(tty);
868
869    printk(KERN_INFO "HVCS: vty-server@%X removed from the"
870            " vio bus.\n", dev->unit_address);
871    return 0;
872};
873
874static struct vio_driver hvcs_vio_driver = {
875    .id_table = hvcs_driver_table,
876    .probe = hvcs_probe,
877    .remove = hvcs_remove,
878    .name = hvcs_driver_name,
879};
880
881/* Only called from hvcs_get_pi please */
882static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
883{
884    hvcsd->p_unit_address = pi->unit_address;
885    hvcsd->p_partition_ID = pi->partition_ID;
886
887    /* copy the null-term char too */
888    strlcpy(&hvcsd->p_location_code[0],
889            &pi->location_code[0], sizeof(hvcsd->p_location_code));
890}
891
892/*
893 * Traverse the list and add the partner info that is found to the hvcs_struct
894 * struct entry. NOTE: At this time I know that partner info will return a
895 * single entry but in the future there may be multiple partner info entries per
896 * vty-server and you'll want to zero out that list and reset it. If for some
897 * reason you have an old version of this driver but there IS more than one
898 * partner info then hvcsd->p_* will hold the last partner info data from the
899 * firmware query. A good way to update this code would be to replace the three
900 * partner info fields in hvcs_struct with a list of hvcs_partner_info
901 * instances.
902 *
903 * This function must be called with the hvcsd->lock held.
904 */
905static int hvcs_get_pi(struct hvcs_struct *hvcsd)
906{
907    struct hvcs_partner_info *pi;
908    uint32_t unit_address = hvcsd->vdev->unit_address;
909    struct list_head head;
910    int retval;
911
912    spin_lock(&hvcs_pi_lock);
913    if (!hvcs_pi_buff) {
914        spin_unlock(&hvcs_pi_lock);
915        return -EFAULT;
916    }
917    retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
918    spin_unlock(&hvcs_pi_lock);
919    if (retval) {
920        printk(KERN_ERR "HVCS: Failed to fetch partner"
921            " info for vty-server@%x.\n", unit_address);
922        return retval;
923    }
924
925    /* nixes the values if the partner vty went away */
926    hvcsd->p_unit_address = 0;
927    hvcsd->p_partition_ID = 0;
928
929    list_for_each_entry(pi, &head, node)
930        hvcs_set_pi(pi, hvcsd);
931
932    hvcs_free_partner_info(&head);
933    return 0;
934}
935
936/*
937 * This function is executed by the driver "rescan" sysfs entry. It shouldn't
938 * be executed elsewhere, in order to prevent deadlock issues.
939 */
940static int hvcs_rescan_devices_list(void)
941{
942    struct hvcs_struct *hvcsd;
943    unsigned long flags;
944
945    spin_lock(&hvcs_structs_lock);
946
947    list_for_each_entry(hvcsd, &hvcs_structs, next) {
948        spin_lock_irqsave(&hvcsd->lock, flags);
949        hvcs_get_pi(hvcsd);
950        spin_unlock_irqrestore(&hvcsd->lock, flags);
951    }
952
953    spin_unlock(&hvcs_structs_lock);
954
955    return 0;
956}
957
958/*
959 * Farm this off into its own function because it could be more complex once
960 * multiple partners support is added. This function should be called with
961 * the hvcsd->lock held.
962 */
963static int hvcs_has_pi(struct hvcs_struct *hvcsd)
964{
965    if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
966        return 0;
967    return 1;
968}
969
970/*
971 * NOTE: It is possible that the super admin removed a partner vty and then
972 * added a different vty as the new partner.
973 *
974 * This function must be called with the hvcsd->lock held.
975 */
976static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
977{
978    int retval;
979    unsigned int unit_address = hvcsd->vdev->unit_address;
980
981    /*
982     * If there wasn't any pi when the device was added it doesn't meant
983     * there isn't any now. This driver isn't notified when a new partner
984     * vty is added to a vty-server so we discover changes on our own.
985     * Please see comments in hvcs_register_connection() for justification
986     * of this bizarre code.
987     */
988    retval = hvcs_register_connection(unit_address,
989            hvcsd->p_partition_ID,
990            hvcsd->p_unit_address);
991    if (!retval) {
992        hvcsd->connected = 1;
993        return 0;
994    } else if (retval != -EINVAL)
995        return retval;
996
997    /*
998     * As per the spec re-get the pi and try again if -EINVAL after the
999     * first connection attempt.
1000     */
1001    if (hvcs_get_pi(hvcsd))
1002        return -ENOMEM;
1003
1004    if (!hvcs_has_pi(hvcsd))
1005        return -ENODEV;
1006
1007    retval = hvcs_register_connection(unit_address,
1008            hvcsd->p_partition_ID,
1009            hvcsd->p_unit_address);
1010    if (retval != -EINVAL) {
1011        hvcsd->connected = 1;
1012        return retval;
1013    }
1014
1015    /*
1016     * EBUSY is the most likely scenario though the vty could have been
1017     * removed or there really could be an hcall error due to the parameter
1018     * data but thanks to ambiguous firmware return codes we can't really
1019     * tell.
1020     */
1021    printk(KERN_INFO "HVCS: vty-server or partner"
1022            " vty is busy. Try again later.\n");
1023    return -EBUSY;
1024}
1025
1026/* This function must be called with the hvcsd->lock held */
1027static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1028{
1029    int retval;
1030    do {
1031        retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1032    } while (retval == -EBUSY);
1033    hvcsd->connected = 0;
1034}
1035
1036/* This helper function must be called WITHOUT the hvcsd->lock held */
1037static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1038        unsigned int irq, struct vio_dev *vdev)
1039{
1040    unsigned long flags;
1041    int rc;
1042
1043    /*
1044     * It is possible that the vty-server was removed between the time that
1045     * the conn was registered and now.
1046     */
1047    if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
1048                0, "ibmhvcs", hvcsd))) {
1049        /*
1050         * It is possible the vty-server was removed after the irq was
1051         * requested but before we have time to enable interrupts.
1052         */
1053        if (vio_enable_interrupts(vdev) == H_SUCCESS)
1054            return 0;
1055        else {
1056            printk(KERN_ERR "HVCS: int enable failed for"
1057                    " vty-server@%X.\n", unit_address);
1058            free_irq(irq, hvcsd);
1059        }
1060    } else
1061        printk(KERN_ERR "HVCS: irq req failed for"
1062                " vty-server@%X.\n", unit_address);
1063
1064    spin_lock_irqsave(&hvcsd->lock, flags);
1065    hvcs_partner_free(hvcsd);
1066    spin_unlock_irqrestore(&hvcsd->lock, flags);
1067
1068    return rc;
1069
1070}
1071
1072/*
1073 * This always increments the kref ref count if the call is successful.
1074 * Please remember to dec when you are done with the instance.
1075 *
1076 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1077 * calling this function or you will get deadlock.
1078 */
1079static struct hvcs_struct *hvcs_get_by_index(int index)
1080{
1081    struct hvcs_struct *hvcsd;
1082    unsigned long flags;
1083
1084    spin_lock(&hvcs_structs_lock);
1085    list_for_each_entry(hvcsd, &hvcs_structs, next) {
1086        spin_lock_irqsave(&hvcsd->lock, flags);
1087        if (hvcsd->index == index) {
1088            tty_port_get(&hvcsd->port);
1089            spin_unlock_irqrestore(&hvcsd->lock, flags);
1090            spin_unlock(&hvcs_structs_lock);
1091            return hvcsd;
1092        }
1093        spin_unlock_irqrestore(&hvcsd->lock, flags);
1094    }
1095    spin_unlock(&hvcs_structs_lock);
1096
1097    return NULL;
1098}
1099
1100static int hvcs_install(struct tty_driver *driver, struct tty_struct *tty)
1101{
1102    struct hvcs_struct *hvcsd;
1103    struct vio_dev *vdev;
1104    unsigned long unit_address, flags;
1105    unsigned int irq;
1106    int retval;
1107
1108    /*
1109     * Is there a vty-server that shares the same index?
1110     * This function increments the kref index.
1111     */
1112    hvcsd = hvcs_get_by_index(tty->index);
1113    if (!hvcsd) {
1114        printk(KERN_WARNING "HVCS: open failed, no device associated"
1115                " with tty->index %d.\n", tty->index);
1116        return -ENODEV;
1117    }
1118
1119    spin_lock_irqsave(&hvcsd->lock, flags);
1120
1121    if (hvcsd->connected == 0) {
1122        retval = hvcs_partner_connect(hvcsd);
1123        if (retval) {
1124            spin_unlock_irqrestore(&hvcsd->lock, flags);
1125            printk(KERN_WARNING "HVCS: partner connect failed.\n");
1126            goto err_put;
1127        }
1128    }
1129
1130    hvcsd->port.count = 0;
1131    hvcsd->port.tty = tty;
1132    tty->driver_data = hvcsd;
1133
1134    memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1135
1136    /*
1137     * Save these in the spinlock for the enable operations that need them
1138     * outside of the spinlock.
1139     */
1140    irq = hvcsd->vdev->irq;
1141    vdev = hvcsd->vdev;
1142    unit_address = hvcsd->vdev->unit_address;
1143
1144    hvcsd->todo_mask |= HVCS_SCHED_READ;
1145    spin_unlock_irqrestore(&hvcsd->lock, flags);
1146
1147    /*
1148     * This must be done outside of the spinlock because it requests irqs
1149     * and will grab the spinlock and free the connection if it fails.
1150     */
1151    retval = hvcs_enable_device(hvcsd, unit_address, irq, vdev);
1152    if (retval) {
1153        printk(KERN_WARNING "HVCS: enable device failed.\n");
1154        goto err_put;
1155    }
1156
1157    retval = tty_port_install(&hvcsd->port, driver, tty);
1158    if (retval)
1159        goto err_irq;
1160
1161    return 0;
1162err_irq:
1163    spin_lock_irqsave(&hvcsd->lock, flags);
1164    vio_disable_interrupts(hvcsd->vdev);
1165    spin_unlock_irqrestore(&hvcsd->lock, flags);
1166    free_irq(irq, hvcsd);
1167err_put:
1168    tty_port_put(&hvcsd->port);
1169
1170    return retval;
1171}
1172
1173/*
1174 * This is invoked via the tty_open interface when a user app connects to the
1175 * /dev node.
1176 */
1177static int hvcs_open(struct tty_struct *tty, struct file *filp)
1178{
1179    struct hvcs_struct *hvcsd = tty->driver_data;
1180    unsigned long flags;
1181
1182    spin_lock_irqsave(&hvcsd->lock, flags);
1183    hvcsd->port.count++;
1184    hvcsd->todo_mask |= HVCS_SCHED_READ;
1185    spin_unlock_irqrestore(&hvcsd->lock, flags);
1186
1187    hvcs_kick();
1188
1189    printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1190        hvcsd->vdev->unit_address );
1191
1192    return 0;
1193}
1194
1195static void hvcs_close(struct tty_struct *tty, struct file *filp)
1196{
1197    struct hvcs_struct *hvcsd;
1198    unsigned long flags;
1199    int irq;
1200
1201    /*
1202     * Is someone trying to close the file associated with this device after
1203     * we have hung up? If so tty->driver_data wouldn't be valid.
1204     */
1205    if (tty_hung_up_p(filp))
1206        return;
1207
1208    /*
1209     * No driver_data means that this close was probably issued after a
1210     * failed hvcs_open by the tty layer's release_dev() api and we can just
1211     * exit cleanly.
1212     */
1213    if (!tty->driver_data)
1214        return;
1215
1216    hvcsd = tty->driver_data;
1217
1218    spin_lock_irqsave(&hvcsd->lock, flags);
1219    if (--hvcsd->port.count == 0) {
1220
1221        vio_disable_interrupts(hvcsd->vdev);
1222
1223        /*
1224         * NULL this early so that the kernel_thread doesn't try to
1225         * execute any operations on the TTY even though it is obligated
1226         * to deliver any pending I/O to the hypervisor.
1227         */
1228        hvcsd->port.tty = NULL;
1229
1230        irq = hvcsd->vdev->irq;
1231        spin_unlock_irqrestore(&hvcsd->lock, flags);
1232
1233        tty_wait_until_sent_from_close(tty, HVCS_CLOSE_WAIT);
1234
1235        /*
1236         * This line is important because it tells hvcs_open that this
1237         * device needs to be re-configured the next time hvcs_open is
1238         * called.
1239         */
1240        tty->driver_data = NULL;
1241
1242        free_irq(irq, hvcsd);
1243        return;
1244    } else if (hvcsd->port.count < 0) {
1245        printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
1246                " is missmanaged.\n",
1247        hvcsd->vdev->unit_address, hvcsd->port.count);
1248    }
1249
1250    spin_unlock_irqrestore(&hvcsd->lock, flags);
1251}
1252
1253static void hvcs_cleanup(struct tty_struct * tty)
1254{
1255    struct hvcs_struct *hvcsd = tty->driver_data;
1256
1257    tty_port_put(&hvcsd->port);
1258}
1259
1260static void hvcs_hangup(struct tty_struct * tty)
1261{
1262    struct hvcs_struct *hvcsd = tty->driver_data;
1263    unsigned long flags;
1264    int temp_open_count;
1265    int irq;
1266
1267    spin_lock_irqsave(&hvcsd->lock, flags);
1268    /* Preserve this so that we know how many kref refs to put */
1269    temp_open_count = hvcsd->port.count;
1270
1271    /*
1272     * Don't kref put inside the spinlock because the destruction
1273     * callback may use the spinlock and it may get called before the
1274     * spinlock has been released.
1275     */
1276    vio_disable_interrupts(hvcsd->vdev);
1277
1278    hvcsd->todo_mask = 0;
1279
1280    /* I don't think the tty needs the hvcs_struct pointer after a hangup */
1281    tty->driver_data = NULL;
1282    hvcsd->port.tty = NULL;
1283
1284    hvcsd->port.count = 0;
1285
1286    /* This will drop any buffered data on the floor which is OK in a hangup
1287     * scenario. */
1288    memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1289    hvcsd->chars_in_buffer = 0;
1290
1291    irq = hvcsd->vdev->irq;
1292
1293    spin_unlock_irqrestore(&hvcsd->lock, flags);
1294
1295    free_irq(irq, hvcsd);
1296
1297    /*
1298     * We need to kref_put() for every open_count we have since the
1299     * tty_hangup() function doesn't invoke a close per open connection on a
1300     * non-console device.
1301     */
1302    while(temp_open_count) {
1303        --temp_open_count;
1304        /*
1305         * The final put will trigger destruction of the hvcs_struct.
1306         * NOTE: If this hangup was signaled from user space then the
1307         * final put will never happen.
1308         */
1309        tty_port_put(&hvcsd->port);
1310    }
1311}
1312
1313/*
1314 * NOTE: This is almost always from_user since user level apps interact with the
1315 * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1316 * hvcs_remove (which removes the target device and executes tty_hangup()) that
1317 * tty_hangup will allow hvcs_write time to complete execution before it
1318 * terminates our device.
1319 */
1320static int hvcs_write(struct tty_struct *tty,
1321        const unsigned char *buf, int count)
1322{
1323    struct hvcs_struct *hvcsd = tty->driver_data;
1324    unsigned int unit_address;
1325    const unsigned char *charbuf;
1326    unsigned long flags;
1327    int total_sent = 0;
1328    int tosend = 0;
1329    int result = 0;
1330
1331    /*
1332     * If they don't check the return code off of their open they may
1333     * attempt this even if there is no connected device.
1334     */
1335    if (!hvcsd)
1336        return -ENODEV;
1337
1338    /* Reasonable size to prevent user level flooding */
1339    if (count > HVCS_MAX_FROM_USER) {
1340        printk(KERN_WARNING "HVCS write: count being truncated to"
1341                " HVCS_MAX_FROM_USER.\n");
1342        count = HVCS_MAX_FROM_USER;
1343    }
1344
1345    charbuf = buf;
1346
1347    spin_lock_irqsave(&hvcsd->lock, flags);
1348
1349    /*
1350     * Somehow an open succeeded but the device was removed or the
1351     * connection terminated between the vty-server and partner vty during
1352     * the middle of a write operation? This is a crummy place to do this
1353     * but we want to keep it all in the spinlock.
1354     */
1355    if (hvcsd->port.count <= 0) {
1356        spin_unlock_irqrestore(&hvcsd->lock, flags);
1357        return -ENODEV;
1358    }
1359
1360    unit_address = hvcsd->vdev->unit_address;
1361
1362    while (count > 0) {
1363        tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1364        /*
1365         * No more space, this probably means that the last call to
1366         * hvcs_write() didn't succeed and the buffer was filled up.
1367         */
1368        if (!tosend)
1369            break;
1370
1371        memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1372                &charbuf[total_sent],
1373                tosend);
1374
1375        hvcsd->chars_in_buffer += tosend;
1376
1377        result = 0;
1378
1379        /*
1380         * If this is true then we don't want to try writing to the
1381         * hypervisor because that is the kernel_threads job now. We'll
1382         * just add to the buffer.
1383         */
1384        if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1385            /* won't send partial writes */
1386            result = hvc_put_chars(unit_address,
1387                    &hvcsd->buffer[0],
1388                    hvcsd->chars_in_buffer);
1389
1390        /*
1391         * Since we know we have enough room in hvcsd->buffer for
1392         * tosend we record that it was sent regardless of whether the
1393         * hypervisor actually took it because we have it buffered.
1394         */
1395        total_sent+=tosend;
1396        count-=tosend;
1397        if (result == 0) {
1398            hvcsd->todo_mask |= HVCS_TRY_WRITE;
1399            hvcs_kick();
1400            break;
1401        }
1402
1403        hvcsd->chars_in_buffer = 0;
1404        /*
1405         * Test after the chars_in_buffer reset otherwise this could
1406         * deadlock our writes if hvc_put_chars fails.
1407         */
1408        if (result < 0)
1409            break;
1410    }
1411
1412    spin_unlock_irqrestore(&hvcsd->lock, flags);
1413
1414    if (result == -1)
1415        return -EIO;
1416    else
1417        return total_sent;
1418}
1419
1420/*
1421 * This is really asking how much can we guarantee that we can send or that we
1422 * absolutely WILL BUFFER if we can't send it. This driver MUST honor the
1423 * return value, hence the reason for hvcs_struct buffering.
1424 */
1425static int hvcs_write_room(struct tty_struct *tty)
1426{
1427    struct hvcs_struct *hvcsd = tty->driver_data;
1428
1429    if (!hvcsd || hvcsd->port.count <= 0)
1430        return 0;
1431
1432    return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1433}
1434
1435static int hvcs_chars_in_buffer(struct tty_struct *tty)
1436{
1437    struct hvcs_struct *hvcsd = tty->driver_data;
1438
1439    return hvcsd->chars_in_buffer;
1440}
1441
1442static const struct tty_operations hvcs_ops = {
1443    .install = hvcs_install,
1444    .open = hvcs_open,
1445    .close = hvcs_close,
1446    .cleanup = hvcs_cleanup,
1447    .hangup = hvcs_hangup,
1448    .write = hvcs_write,
1449    .write_room = hvcs_write_room,
1450    .chars_in_buffer = hvcs_chars_in_buffer,
1451    .unthrottle = hvcs_unthrottle,
1452    .throttle = hvcs_throttle,
1453};
1454
1455static int hvcs_alloc_index_list(int n)
1456{
1457    int i;
1458
1459    hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
1460    if (!hvcs_index_list)
1461        return -ENOMEM;
1462    hvcs_index_count = n;
1463    for (i = 0; i < hvcs_index_count; i++)
1464        hvcs_index_list[i] = -1;
1465    return 0;
1466}
1467
1468static void hvcs_free_index_list(void)
1469{
1470    /* Paranoia check to be thorough. */
1471    kfree(hvcs_index_list);
1472    hvcs_index_list = NULL;
1473    hvcs_index_count = 0;
1474}
1475
1476static int hvcs_initialize(void)
1477{
1478    int rc, num_ttys_to_alloc;
1479
1480    mutex_lock(&hvcs_init_mutex);
1481    if (hvcs_task) {
1482        mutex_unlock(&hvcs_init_mutex);
1483        return 0;
1484    }
1485
1486    /* Has the user specified an overload with an insmod param? */
1487    if (hvcs_parm_num_devs <= 0 ||
1488        (hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
1489        num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
1490    } else
1491        num_ttys_to_alloc = hvcs_parm_num_devs;
1492
1493    hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
1494    if (!hvcs_tty_driver) {
1495        mutex_unlock(&hvcs_init_mutex);
1496        return -ENOMEM;
1497    }
1498
1499    if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1500        rc = -ENOMEM;
1501        goto index_fail;
1502    }
1503
1504    hvcs_tty_driver->driver_name = hvcs_driver_name;
1505    hvcs_tty_driver->name = hvcs_device_node;
1506
1507    /*
1508     * We'll let the system assign us a major number, indicated by leaving
1509     * it blank.
1510     */
1511
1512    hvcs_tty_driver->minor_start = HVCS_MINOR_START;
1513    hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1514
1515    /*
1516     * We role our own so that we DONT ECHO. We can't echo because the
1517     * device we are connecting to already echoes by default and this would
1518     * throw us into a horrible recursive echo-echo-echo loop.
1519     */
1520    hvcs_tty_driver->init_termios = hvcs_tty_termios;
1521    hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
1522
1523    tty_set_operations(hvcs_tty_driver, &hvcs_ops);
1524
1525    /*
1526     * The following call will result in sysfs entries that denote the
1527     * dynamically assigned major and minor numbers for our devices.
1528     */
1529    if (tty_register_driver(hvcs_tty_driver)) {
1530        printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
1531        rc = -EIO;
1532        goto register_fail;
1533    }
1534
1535    hvcs_pi_buff = (unsigned long *) __get_free_page(GFP_KERNEL);
1536    if (!hvcs_pi_buff) {
1537        rc = -ENOMEM;
1538        goto buff_alloc_fail;
1539    }
1540
1541    hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
1542    if (IS_ERR(hvcs_task)) {
1543        printk(KERN_ERR "HVCS: khvcsd creation failed.\n");
1544        rc = -EIO;
1545        goto kthread_fail;
1546    }
1547    mutex_unlock(&hvcs_init_mutex);
1548    return 0;
1549
1550kthread_fail:
1551    free_page((unsigned long)hvcs_pi_buff);
1552buff_alloc_fail:
1553    tty_unregister_driver(hvcs_tty_driver);
1554register_fail:
1555    hvcs_free_index_list();
1556index_fail:
1557    put_tty_driver(hvcs_tty_driver);
1558    hvcs_tty_driver = NULL;
1559    mutex_unlock(&hvcs_init_mutex);
1560    return rc;
1561}
1562
1563static int __init hvcs_module_init(void)
1564{
1565    int rc = vio_register_driver(&hvcs_vio_driver);
1566    if (rc) {
1567        printk(KERN_ERR "HVCS: can't register vio driver\n");
1568        return rc;
1569    }
1570
1571    pr_info("HVCS: Driver registered.\n");
1572
1573    /* This needs to be done AFTER the vio_register_driver() call or else
1574     * the kobjects won't be initialized properly.
1575     */
1576    rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
1577    if (rc)
1578        pr_warning(KERN_ERR "HVCS: Failed to create rescan file (err %d)\n", rc);
1579
1580    return 0;
1581}
1582
1583static void __exit hvcs_module_exit(void)
1584{
1585    /*
1586     * This driver receives hvcs_remove callbacks for each device upon
1587     * module removal.
1588     */
1589    vio_unregister_driver(&hvcs_vio_driver);
1590    if (!hvcs_task)
1591        return;
1592
1593    /*
1594     * This synchronous operation will wake the khvcsd kthread if it is
1595     * asleep and will return when khvcsd has terminated.
1596     */
1597    kthread_stop(hvcs_task);
1598
1599    spin_lock(&hvcs_pi_lock);
1600    free_page((unsigned long)hvcs_pi_buff);
1601    hvcs_pi_buff = NULL;
1602    spin_unlock(&hvcs_pi_lock);
1603
1604    driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
1605
1606    tty_unregister_driver(hvcs_tty_driver);
1607
1608    hvcs_free_index_list();
1609
1610    put_tty_driver(hvcs_tty_driver);
1611
1612    printk(KERN_INFO "HVCS: driver module removed.\n");
1613}
1614
1615module_init(hvcs_module_init);
1616module_exit(hvcs_module_exit);
1617

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