Add linux-next specific files for 20110831
[linux-2.6/next.git] / drivers / tty / hvc / hvcs.c
blobe523773a548061c8f4a782f665b27a83c1ef71ac
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)
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.
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.
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
20 * Author(s) : Ryan S. Arnold <rsa@us.ibm.com>
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.
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.
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.
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.
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.
59 * Each vty-server, prior to being exposed to this driver is reference counted
60 * using the 2.6 Linux kernel kref construct.
62 * For direction on installation and usage of this driver please reference
63 * Documentation/powerpc/hvcs.txt.
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>
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().
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
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.
128 #define HVCS_DRIVER_VERSION "1.3.3"
130 MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
131 MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
132 MODULE_LICENSE("GPL");
133 MODULE_VERSION(HVCS_DRIVER_VERSION);
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.
139 #define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
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.
149 #define HVCS_DEFAULT_SERVER_ADAPTERS 64
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.
156 #define HVCS_MAX_SERVER_ADAPTERS 1024
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.
164 #define HVCS_MINOR_START 0
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.
173 #define __ALIGNED__ __attribute__((__aligned__(8)))
176 * How much data can firmware send with each hvc_put_chars()? Maybe this
177 * should be moved into an architecture specific area.
179 #define HVCS_BUFF_LEN 16
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.
185 #define HVCS_MAX_FROM_USER 4096
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.
192 static 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
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.
207 static int hvcs_parm_num_devs = -1;
208 module_param(hvcs_parm_num_devs, int, 0);
210 static const char hvcs_driver_name[] = "hvcs";
211 static const char hvcs_device_node[] = "hvcs";
212 static const char hvcs_driver_string[]
213 = "IBM hvcs (Hypervisor Virtual Console Server) Driver";
215 /* Status of partner info rescan triggered via sysfs. */
216 static int hvcs_rescan_status;
218 static struct tty_driver *hvcs_tty_driver;
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.
233 static int *hvcs_index_list;
236 * How large is the list? This is kept for traversal since the list is
237 * dynamically created.
239 static int hvcs_index_count;
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.
245 static int hvcs_kicked;
248 * Use by the kthread construct for task operations like waking the sleeping
249 * thread and stopping the kthread.
251 static struct task_struct *hvcs_task;
254 * We allocate this for the use of all of the hvcs_structs when they fetch
255 * partner info.
257 static unsigned long *hvcs_pi_buff;
259 /* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
260 static DEFINE_SPINLOCK(hvcs_pi_lock);
262 /* One vty-server per hvcs_struct */
263 struct hvcs_struct {
264 spinlock_t lock;
267 * This index identifies this hvcs device as the complement to a
268 * specific tty index.
270 unsigned int index;
272 struct tty_struct *tty;
273 int open_count;
276 * Used to tell the driver kernel_thread what operations need to take
277 * place upon this hvcs_struct instance.
279 int todo_mask;
282 * This buffer is required so that when hvcs_write_room() reports that
283 * it can send HVCS_BUFF_LEN characters that it will buffer the full
284 * HVCS_BUFF_LEN characters if need be. This is essential for opost
285 * writes since they do not do high level buffering and expect to be
286 * able to send what the driver commits to sending buffering
287 * [e.g. tab to space conversions in n_tty.c opost()].
289 char buffer[HVCS_BUFF_LEN];
290 int chars_in_buffer;
293 * Any variable below the kref is valid before a tty is connected and
294 * stays valid after the tty is disconnected. These shouldn't be
295 * whacked until the kobject refcount reaches zero though some entries
296 * may be changed via sysfs initiatives.
298 struct kref kref; /* ref count & hvcs_struct lifetime */
299 int connected; /* is the vty-server currently connected to a vty? */
300 uint32_t p_unit_address; /* partner unit address */
301 uint32_t p_partition_ID; /* partner partition ID */
302 char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
303 struct list_head next; /* list management */
304 struct vio_dev *vdev;
307 /* Required to back map a kref to its containing object */
308 #define from_kref(k) container_of(k, struct hvcs_struct, kref)
310 static LIST_HEAD(hvcs_structs);
311 static DEFINE_SPINLOCK(hvcs_structs_lock);
312 static DEFINE_MUTEX(hvcs_init_mutex);
314 static void hvcs_unthrottle(struct tty_struct *tty);
315 static void hvcs_throttle(struct tty_struct *tty);
316 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
318 static int hvcs_write(struct tty_struct *tty,
319 const unsigned char *buf, int count);
320 static int hvcs_write_room(struct tty_struct *tty);
321 static int hvcs_chars_in_buffer(struct tty_struct *tty);
323 static int hvcs_has_pi(struct hvcs_struct *hvcsd);
324 static void hvcs_set_pi(struct hvcs_partner_info *pi,
325 struct hvcs_struct *hvcsd);
326 static int hvcs_get_pi(struct hvcs_struct *hvcsd);
327 static int hvcs_rescan_devices_list(void);
329 static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
330 static void hvcs_partner_free(struct hvcs_struct *hvcsd);
332 static int hvcs_enable_device(struct hvcs_struct *hvcsd,
333 uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
335 static int hvcs_open(struct tty_struct *tty, struct file *filp);
336 static void hvcs_close(struct tty_struct *tty, struct file *filp);
337 static void hvcs_hangup(struct tty_struct * tty);
339 static int __devinit hvcs_probe(struct vio_dev *dev,
340 const struct vio_device_id *id);
341 static int __devexit hvcs_remove(struct vio_dev *dev);
342 static int __init hvcs_module_init(void);
343 static void __exit hvcs_module_exit(void);
344 static int __devinit hvcs_initialize(void);
346 #define HVCS_SCHED_READ 0x00000001
347 #define HVCS_QUICK_READ 0x00000002
348 #define HVCS_TRY_WRITE 0x00000004
349 #define HVCS_READ_MASK (HVCS_SCHED_READ | HVCS_QUICK_READ)
351 static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
353 return dev_get_drvdata(&viod->dev);
355 /* The sysfs interface for the driver and devices */
357 static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
359 struct vio_dev *viod = to_vio_dev(dev);
360 struct hvcs_struct *hvcsd = from_vio_dev(viod);
361 unsigned long flags;
362 int retval;
364 spin_lock_irqsave(&hvcsd->lock, flags);
365 retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
366 spin_unlock_irqrestore(&hvcsd->lock, flags);
367 return retval;
369 static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
371 static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
373 struct vio_dev *viod = to_vio_dev(dev);
374 struct hvcs_struct *hvcsd = from_vio_dev(viod);
375 unsigned long flags;
376 int retval;
378 spin_lock_irqsave(&hvcsd->lock, flags);
379 retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
380 spin_unlock_irqrestore(&hvcsd->lock, flags);
381 return retval;
383 static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
385 static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
386 size_t count)
389 * Don't need this feature at the present time because firmware doesn't
390 * yet support multiple partners.
392 printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
393 return -EPERM;
396 static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
398 struct vio_dev *viod = to_vio_dev(dev);
399 struct hvcs_struct *hvcsd = from_vio_dev(viod);
400 unsigned long flags;
401 int retval;
403 spin_lock_irqsave(&hvcsd->lock, flags);
404 retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
405 spin_unlock_irqrestore(&hvcsd->lock, flags);
406 return retval;
409 static DEVICE_ATTR(current_vty,
410 S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
412 static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
413 size_t count)
415 struct vio_dev *viod = to_vio_dev(dev);
416 struct hvcs_struct *hvcsd = from_vio_dev(viod);
417 unsigned long flags;
419 /* writing a '0' to this sysfs entry will result in the disconnect. */
420 if (simple_strtol(buf, NULL, 0) != 0)
421 return -EINVAL;
423 spin_lock_irqsave(&hvcsd->lock, flags);
425 if (hvcsd->open_count > 0) {
426 spin_unlock_irqrestore(&hvcsd->lock, flags);
427 printk(KERN_INFO "HVCS: vterm state unchanged. "
428 "The hvcs device node is still in use.\n");
429 return -EPERM;
432 if (hvcsd->connected == 0) {
433 spin_unlock_irqrestore(&hvcsd->lock, flags);
434 printk(KERN_INFO "HVCS: vterm state unchanged. The"
435 " vty-server is not connected to a vty.\n");
436 return -EPERM;
439 hvcs_partner_free(hvcsd);
440 printk(KERN_INFO "HVCS: Closed vty-server@%X and"
441 " partner vty@%X:%d connection.\n",
442 hvcsd->vdev->unit_address,
443 hvcsd->p_unit_address,
444 (uint32_t)hvcsd->p_partition_ID);
446 spin_unlock_irqrestore(&hvcsd->lock, flags);
447 return count;
450 static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
452 struct vio_dev *viod = to_vio_dev(dev);
453 struct hvcs_struct *hvcsd = from_vio_dev(viod);
454 unsigned long flags;
455 int retval;
457 spin_lock_irqsave(&hvcsd->lock, flags);
458 retval = sprintf(buf, "%d\n", hvcsd->connected);
459 spin_unlock_irqrestore(&hvcsd->lock, flags);
460 return retval;
462 static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
463 hvcs_vterm_state_show, hvcs_vterm_state_store);
465 static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
467 struct vio_dev *viod = to_vio_dev(dev);
468 struct hvcs_struct *hvcsd = from_vio_dev(viod);
469 unsigned long flags;
470 int retval;
472 spin_lock_irqsave(&hvcsd->lock, flags);
473 retval = sprintf(buf, "%d\n", hvcsd->index);
474 spin_unlock_irqrestore(&hvcsd->lock, flags);
475 return retval;
478 static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
480 static struct attribute *hvcs_attrs[] = {
481 &dev_attr_partner_vtys.attr,
482 &dev_attr_partner_clcs.attr,
483 &dev_attr_current_vty.attr,
484 &dev_attr_vterm_state.attr,
485 &dev_attr_index.attr,
486 NULL,
489 static struct attribute_group hvcs_attr_group = {
490 .attrs = hvcs_attrs,
493 static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
495 /* A 1 means it is updating, a 0 means it is done updating */
496 return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
499 static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
500 size_t count)
502 if ((simple_strtol(buf, NULL, 0) != 1)
503 && (hvcs_rescan_status != 0))
504 return -EINVAL;
506 hvcs_rescan_status = 1;
507 printk(KERN_INFO "HVCS: rescanning partner info for all"
508 " vty-servers.\n");
509 hvcs_rescan_devices_list();
510 hvcs_rescan_status = 0;
511 return count;
514 static DRIVER_ATTR(rescan,
515 S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
517 static void hvcs_kick(void)
519 hvcs_kicked = 1;
520 wmb();
521 wake_up_process(hvcs_task);
524 static void hvcs_unthrottle(struct tty_struct *tty)
526 struct hvcs_struct *hvcsd = tty->driver_data;
527 unsigned long flags;
529 spin_lock_irqsave(&hvcsd->lock, flags);
530 hvcsd->todo_mask |= HVCS_SCHED_READ;
531 spin_unlock_irqrestore(&hvcsd->lock, flags);
532 hvcs_kick();
535 static void hvcs_throttle(struct tty_struct *tty)
537 struct hvcs_struct *hvcsd = tty->driver_data;
538 unsigned long flags;
540 spin_lock_irqsave(&hvcsd->lock, flags);
541 vio_disable_interrupts(hvcsd->vdev);
542 spin_unlock_irqrestore(&hvcsd->lock, flags);
546 * If the device is being removed we don't have to worry about this interrupt
547 * handler taking any further interrupts because they are disabled which means
548 * the hvcs_struct will always be valid in this handler.
550 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
552 struct hvcs_struct *hvcsd = dev_instance;
554 spin_lock(&hvcsd->lock);
555 vio_disable_interrupts(hvcsd->vdev);
556 hvcsd->todo_mask |= HVCS_SCHED_READ;
557 spin_unlock(&hvcsd->lock);
558 hvcs_kick();
560 return IRQ_HANDLED;
563 /* This function must be called with the hvcsd->lock held */
564 static void hvcs_try_write(struct hvcs_struct *hvcsd)
566 uint32_t unit_address = hvcsd->vdev->unit_address;
567 struct tty_struct *tty = hvcsd->tty;
568 int sent;
570 if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
571 /* won't send partial writes */
572 sent = hvc_put_chars(unit_address,
573 &hvcsd->buffer[0],
574 hvcsd->chars_in_buffer );
575 if (sent > 0) {
576 hvcsd->chars_in_buffer = 0;
577 /* wmb(); */
578 hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
579 /* wmb(); */
582 * We are still obligated to deliver the data to the
583 * hypervisor even if the tty has been closed because
584 * we committed to delivering it. But don't try to wake
585 * a non-existent tty.
587 if (tty) {
588 tty_wakeup(tty);
594 static int hvcs_io(struct hvcs_struct *hvcsd)
596 uint32_t unit_address;
597 struct tty_struct *tty;
598 char buf[HVCS_BUFF_LEN] __ALIGNED__;
599 unsigned long flags;
600 int got = 0;
602 spin_lock_irqsave(&hvcsd->lock, flags);
604 unit_address = hvcsd->vdev->unit_address;
605 tty = hvcsd->tty;
607 hvcs_try_write(hvcsd);
609 if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
610 hvcsd->todo_mask &= ~(HVCS_READ_MASK);
611 goto bail;
612 } else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
613 goto bail;
615 /* remove the read masks */
616 hvcsd->todo_mask &= ~(HVCS_READ_MASK);
618 if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
619 got = hvc_get_chars(unit_address,
620 &buf[0],
621 HVCS_BUFF_LEN);
622 tty_insert_flip_string(tty, buf, got);
625 /* Give the TTY time to process the data we just sent. */
626 if (got)
627 hvcsd->todo_mask |= HVCS_QUICK_READ;
629 spin_unlock_irqrestore(&hvcsd->lock, flags);
630 /* This is synch because tty->low_latency == 1 */
631 if(got)
632 tty_flip_buffer_push(tty);
634 if (!got) {
635 /* Do this _after_ the flip_buffer_push */
636 spin_lock_irqsave(&hvcsd->lock, flags);
637 vio_enable_interrupts(hvcsd->vdev);
638 spin_unlock_irqrestore(&hvcsd->lock, flags);
641 return hvcsd->todo_mask;
643 bail:
644 spin_unlock_irqrestore(&hvcsd->lock, flags);
645 return hvcsd->todo_mask;
648 static int khvcsd(void *unused)
650 struct hvcs_struct *hvcsd;
651 int hvcs_todo_mask;
653 __set_current_state(TASK_RUNNING);
655 do {
656 hvcs_todo_mask = 0;
657 hvcs_kicked = 0;
658 wmb();
660 spin_lock(&hvcs_structs_lock);
661 list_for_each_entry(hvcsd, &hvcs_structs, next) {
662 hvcs_todo_mask |= hvcs_io(hvcsd);
664 spin_unlock(&hvcs_structs_lock);
667 * If any of the hvcs adapters want to try a write or quick read
668 * don't schedule(), yield a smidgen then execute the hvcs_io
669 * thread again for those that want the write.
671 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
672 yield();
673 continue;
676 set_current_state(TASK_INTERRUPTIBLE);
677 if (!hvcs_kicked)
678 schedule();
679 __set_current_state(TASK_RUNNING);
680 } while (!kthread_should_stop());
682 return 0;
685 static struct vio_device_id hvcs_driver_table[] __devinitdata= {
686 {"serial-server", "hvterm2"},
687 { "", "" }
689 MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
691 static void hvcs_return_index(int index)
693 /* Paranoia check */
694 if (!hvcs_index_list)
695 return;
696 if (index < 0 || index >= hvcs_index_count)
697 return;
698 if (hvcs_index_list[index] == -1)
699 return;
700 else
701 hvcs_index_list[index] = -1;
704 /* callback when the kref ref count reaches zero */
705 static void destroy_hvcs_struct(struct kref *kref)
707 struct hvcs_struct *hvcsd = from_kref(kref);
708 struct vio_dev *vdev;
709 unsigned long flags;
711 spin_lock(&hvcs_structs_lock);
712 spin_lock_irqsave(&hvcsd->lock, flags);
714 /* the list_del poisons the pointers */
715 list_del(&(hvcsd->next));
717 if (hvcsd->connected == 1) {
718 hvcs_partner_free(hvcsd);
719 printk(KERN_INFO "HVCS: Closed vty-server@%X and"
720 " partner vty@%X:%d connection.\n",
721 hvcsd->vdev->unit_address,
722 hvcsd->p_unit_address,
723 (uint32_t)hvcsd->p_partition_ID);
725 printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
726 hvcsd->vdev->unit_address);
728 vdev = hvcsd->vdev;
729 hvcsd->vdev = NULL;
731 hvcsd->p_unit_address = 0;
732 hvcsd->p_partition_ID = 0;
733 hvcs_return_index(hvcsd->index);
734 memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
736 spin_unlock_irqrestore(&hvcsd->lock, flags);
737 spin_unlock(&hvcs_structs_lock);
739 sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
741 kfree(hvcsd);
744 static int hvcs_get_index(void)
746 int i;
747 /* Paranoia check */
748 if (!hvcs_index_list) {
749 printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
750 return -EFAULT;
752 /* Find the numerically lowest first free index. */
753 for(i = 0; i < hvcs_index_count; i++) {
754 if (hvcs_index_list[i] == -1) {
755 hvcs_index_list[i] = 0;
756 return i;
759 return -1;
762 static int __devinit hvcs_probe(
763 struct vio_dev *dev,
764 const struct vio_device_id *id)
766 struct hvcs_struct *hvcsd;
767 int index, rc;
768 int retval;
770 if (!dev || !id) {
771 printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
772 return -EPERM;
775 /* Make sure we are properly initialized */
776 rc = hvcs_initialize();
777 if (rc) {
778 pr_err("HVCS: Failed to initialize core driver.\n");
779 return rc;
782 /* early to avoid cleanup on failure */
783 index = hvcs_get_index();
784 if (index < 0) {
785 return -EFAULT;
788 hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
789 if (!hvcsd)
790 return -ENODEV;
793 spin_lock_init(&hvcsd->lock);
794 /* Automatically incs the refcount the first time */
795 kref_init(&hvcsd->kref);
797 hvcsd->vdev = dev;
798 dev_set_drvdata(&dev->dev, hvcsd);
800 hvcsd->index = index;
802 /* hvcsd->index = ++hvcs_struct_count; */
803 hvcsd->chars_in_buffer = 0;
804 hvcsd->todo_mask = 0;
805 hvcsd->connected = 0;
808 * This will populate the hvcs_struct's partner info fields for the
809 * first time.
811 if (hvcs_get_pi(hvcsd)) {
812 printk(KERN_ERR "HVCS: Failed to fetch partner"
813 " info for vty-server@%X on device probe.\n",
814 hvcsd->vdev->unit_address);
818 * If a user app opens a tty that corresponds to this vty-server before
819 * the hvcs_struct has been added to the devices list then the user app
820 * will get -ENODEV.
822 spin_lock(&hvcs_structs_lock);
823 list_add_tail(&(hvcsd->next), &hvcs_structs);
824 spin_unlock(&hvcs_structs_lock);
826 retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
827 if (retval) {
828 printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
829 hvcsd->vdev->unit_address);
830 return retval;
833 printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
836 * DON'T enable interrupts here because there is no user to receive the
837 * data.
839 return 0;
842 static int __devexit hvcs_remove(struct vio_dev *dev)
844 struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
845 unsigned long flags;
846 struct tty_struct *tty;
848 if (!hvcsd)
849 return -ENODEV;
851 /* By this time the vty-server won't be getting any more interrupts */
853 spin_lock_irqsave(&hvcsd->lock, flags);
855 tty = hvcsd->tty;
857 spin_unlock_irqrestore(&hvcsd->lock, flags);
860 * Let the last holder of this object cause it to be removed, which
861 * would probably be tty_hangup below.
863 kref_put(&hvcsd->kref, destroy_hvcs_struct);
866 * The hangup is a scheduled function which will auto chain call
867 * hvcs_hangup. The tty should always be valid at this time unless a
868 * simultaneous tty close already cleaned up the hvcs_struct.
870 if (tty)
871 tty_hangup(tty);
873 printk(KERN_INFO "HVCS: vty-server@%X removed from the"
874 " vio bus.\n", dev->unit_address);
875 return 0;
878 static struct vio_driver hvcs_vio_driver = {
879 .id_table = hvcs_driver_table,
880 .probe = hvcs_probe,
881 .remove = __devexit_p(hvcs_remove),
882 .driver = {
883 .name = hvcs_driver_name,
884 .owner = THIS_MODULE,
888 /* Only called from hvcs_get_pi please */
889 static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
891 int clclength;
893 hvcsd->p_unit_address = pi->unit_address;
894 hvcsd->p_partition_ID = pi->partition_ID;
895 clclength = strlen(&pi->location_code[0]);
896 if (clclength > HVCS_CLC_LENGTH)
897 clclength = HVCS_CLC_LENGTH;
899 /* copy the null-term char too */
900 strncpy(&hvcsd->p_location_code[0],
901 &pi->location_code[0], clclength + 1);
905 * Traverse the list and add the partner info that is found to the hvcs_struct
906 * struct entry. NOTE: At this time I know that partner info will return a
907 * single entry but in the future there may be multiple partner info entries per
908 * vty-server and you'll want to zero out that list and reset it. If for some
909 * reason you have an old version of this driver but there IS more than one
910 * partner info then hvcsd->p_* will hold the last partner info data from the
911 * firmware query. A good way to update this code would be to replace the three
912 * partner info fields in hvcs_struct with a list of hvcs_partner_info
913 * instances.
915 * This function must be called with the hvcsd->lock held.
917 static int hvcs_get_pi(struct hvcs_struct *hvcsd)
919 struct hvcs_partner_info *pi;
920 uint32_t unit_address = hvcsd->vdev->unit_address;
921 struct list_head head;
922 int retval;
924 spin_lock(&hvcs_pi_lock);
925 if (!hvcs_pi_buff) {
926 spin_unlock(&hvcs_pi_lock);
927 return -EFAULT;
929 retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
930 spin_unlock(&hvcs_pi_lock);
931 if (retval) {
932 printk(KERN_ERR "HVCS: Failed to fetch partner"
933 " info for vty-server@%x.\n", unit_address);
934 return retval;
937 /* nixes the values if the partner vty went away */
938 hvcsd->p_unit_address = 0;
939 hvcsd->p_partition_ID = 0;
941 list_for_each_entry(pi, &head, node)
942 hvcs_set_pi(pi, hvcsd);
944 hvcs_free_partner_info(&head);
945 return 0;
949 * This function is executed by the driver "rescan" sysfs entry. It shouldn't
950 * be executed elsewhere, in order to prevent deadlock issues.
952 static int hvcs_rescan_devices_list(void)
954 struct hvcs_struct *hvcsd;
955 unsigned long flags;
957 spin_lock(&hvcs_structs_lock);
959 list_for_each_entry(hvcsd, &hvcs_structs, next) {
960 spin_lock_irqsave(&hvcsd->lock, flags);
961 hvcs_get_pi(hvcsd);
962 spin_unlock_irqrestore(&hvcsd->lock, flags);
965 spin_unlock(&hvcs_structs_lock);
967 return 0;
971 * Farm this off into its own function because it could be more complex once
972 * multiple partners support is added. This function should be called with
973 * the hvcsd->lock held.
975 static int hvcs_has_pi(struct hvcs_struct *hvcsd)
977 if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
978 return 0;
979 return 1;
983 * NOTE: It is possible that the super admin removed a partner vty and then
984 * added a different vty as the new partner.
986 * This function must be called with the hvcsd->lock held.
988 static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
990 int retval;
991 unsigned int unit_address = hvcsd->vdev->unit_address;
994 * If there wasn't any pi when the device was added it doesn't meant
995 * there isn't any now. This driver isn't notified when a new partner
996 * vty is added to a vty-server so we discover changes on our own.
997 * Please see comments in hvcs_register_connection() for justification
998 * of this bizarre code.
1000 retval = hvcs_register_connection(unit_address,
1001 hvcsd->p_partition_ID,
1002 hvcsd->p_unit_address);
1003 if (!retval) {
1004 hvcsd->connected = 1;
1005 return 0;
1006 } else if (retval != -EINVAL)
1007 return retval;
1010 * As per the spec re-get the pi and try again if -EINVAL after the
1011 * first connection attempt.
1013 if (hvcs_get_pi(hvcsd))
1014 return -ENOMEM;
1016 if (!hvcs_has_pi(hvcsd))
1017 return -ENODEV;
1019 retval = hvcs_register_connection(unit_address,
1020 hvcsd->p_partition_ID,
1021 hvcsd->p_unit_address);
1022 if (retval != -EINVAL) {
1023 hvcsd->connected = 1;
1024 return retval;
1028 * EBUSY is the most likely scenario though the vty could have been
1029 * removed or there really could be an hcall error due to the parameter
1030 * data but thanks to ambiguous firmware return codes we can't really
1031 * tell.
1033 printk(KERN_INFO "HVCS: vty-server or partner"
1034 " vty is busy. Try again later.\n");
1035 return -EBUSY;
1038 /* This function must be called with the hvcsd->lock held */
1039 static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1041 int retval;
1042 do {
1043 retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1044 } while (retval == -EBUSY);
1045 hvcsd->connected = 0;
1048 /* This helper function must be called WITHOUT the hvcsd->lock held */
1049 static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1050 unsigned int irq, struct vio_dev *vdev)
1052 unsigned long flags;
1053 int rc;
1056 * It is possible that the vty-server was removed between the time that
1057 * the conn was registered and now.
1059 if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
1060 IRQF_DISABLED, "ibmhvcs", hvcsd))) {
1062 * It is possible the vty-server was removed after the irq was
1063 * requested but before we have time to enable interrupts.
1065 if (vio_enable_interrupts(vdev) == H_SUCCESS)
1066 return 0;
1067 else {
1068 printk(KERN_ERR "HVCS: int enable failed for"
1069 " vty-server@%X.\n", unit_address);
1070 free_irq(irq, hvcsd);
1072 } else
1073 printk(KERN_ERR "HVCS: irq req failed for"
1074 " vty-server@%X.\n", unit_address);
1076 spin_lock_irqsave(&hvcsd->lock, flags);
1077 hvcs_partner_free(hvcsd);
1078 spin_unlock_irqrestore(&hvcsd->lock, flags);
1080 return rc;
1085 * This always increments the kref ref count if the call is successful.
1086 * Please remember to dec when you are done with the instance.
1088 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1089 * calling this function or you will get deadlock.
1091 static struct hvcs_struct *hvcs_get_by_index(int index)
1093 struct hvcs_struct *hvcsd = NULL;
1094 unsigned long flags;
1096 spin_lock(&hvcs_structs_lock);
1097 /* We can immediately discard OOB requests */
1098 if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
1099 list_for_each_entry(hvcsd, &hvcs_structs, next) {
1100 spin_lock_irqsave(&hvcsd->lock, flags);
1101 if (hvcsd->index == index) {
1102 kref_get(&hvcsd->kref);
1103 spin_unlock_irqrestore(&hvcsd->lock, flags);
1104 spin_unlock(&hvcs_structs_lock);
1105 return hvcsd;
1107 spin_unlock_irqrestore(&hvcsd->lock, flags);
1109 hvcsd = NULL;
1112 spin_unlock(&hvcs_structs_lock);
1113 return hvcsd;
1117 * This is invoked via the tty_open interface when a user app connects to the
1118 * /dev node.
1120 static int hvcs_open(struct tty_struct *tty, struct file *filp)
1122 struct hvcs_struct *hvcsd;
1123 int rc, retval = 0;
1124 unsigned long flags;
1125 unsigned int irq;
1126 struct vio_dev *vdev;
1127 unsigned long unit_address;
1129 if (tty->driver_data)
1130 goto fast_open;
1133 * Is there a vty-server that shares the same index?
1134 * This function increments the kref index.
1136 if (!(hvcsd = hvcs_get_by_index(tty->index))) {
1137 printk(KERN_WARNING "HVCS: open failed, no device associated"
1138 " with tty->index %d.\n", tty->index);
1139 return -ENODEV;
1142 spin_lock_irqsave(&hvcsd->lock, flags);
1144 if (hvcsd->connected == 0)
1145 if ((retval = hvcs_partner_connect(hvcsd)))
1146 goto error_release;
1148 hvcsd->open_count = 1;
1149 hvcsd->tty = tty;
1150 tty->driver_data = hvcsd;
1152 memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1155 * Save these in the spinlock for the enable operations that need them
1156 * outside of the spinlock.
1158 irq = hvcsd->vdev->irq;
1159 vdev = hvcsd->vdev;
1160 unit_address = hvcsd->vdev->unit_address;
1162 hvcsd->todo_mask |= HVCS_SCHED_READ;
1163 spin_unlock_irqrestore(&hvcsd->lock, flags);
1166 * This must be done outside of the spinlock because it requests irqs
1167 * and will grab the spinlock and free the connection if it fails.
1169 if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
1170 kref_put(&hvcsd->kref, destroy_hvcs_struct);
1171 printk(KERN_WARNING "HVCS: enable device failed.\n");
1172 return rc;
1175 goto open_success;
1177 fast_open:
1178 hvcsd = tty->driver_data;
1180 spin_lock_irqsave(&hvcsd->lock, flags);
1181 kref_get(&hvcsd->kref);
1182 hvcsd->open_count++;
1183 hvcsd->todo_mask |= HVCS_SCHED_READ;
1184 spin_unlock_irqrestore(&hvcsd->lock, flags);
1186 open_success:
1187 hvcs_kick();
1189 printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1190 hvcsd->vdev->unit_address );
1192 return 0;
1194 error_release:
1195 spin_unlock_irqrestore(&hvcsd->lock, flags);
1196 kref_put(&hvcsd->kref, destroy_hvcs_struct);
1198 printk(KERN_WARNING "HVCS: partner connect failed.\n");
1199 return retval;
1202 static void hvcs_close(struct tty_struct *tty, struct file *filp)
1204 struct hvcs_struct *hvcsd;
1205 unsigned long flags;
1206 int irq = NO_IRQ;
1209 * Is someone trying to close the file associated with this device after
1210 * we have hung up? If so tty->driver_data wouldn't be valid.
1212 if (tty_hung_up_p(filp))
1213 return;
1216 * No driver_data means that this close was probably issued after a
1217 * failed hvcs_open by the tty layer's release_dev() api and we can just
1218 * exit cleanly.
1220 if (!tty->driver_data)
1221 return;
1223 hvcsd = tty->driver_data;
1225 spin_lock_irqsave(&hvcsd->lock, flags);
1226 if (--hvcsd->open_count == 0) {
1228 vio_disable_interrupts(hvcsd->vdev);
1231 * NULL this early so that the kernel_thread doesn't try to
1232 * execute any operations on the TTY even though it is obligated
1233 * to deliver any pending I/O to the hypervisor.
1235 hvcsd->tty = NULL;
1237 irq = hvcsd->vdev->irq;
1238 spin_unlock_irqrestore(&hvcsd->lock, flags);
1240 tty_wait_until_sent_from_close(tty, HVCS_CLOSE_WAIT);
1243 * This line is important because it tells hvcs_open that this
1244 * device needs to be re-configured the next time hvcs_open is
1245 * called.
1247 tty->driver_data = NULL;
1249 free_irq(irq, hvcsd);
1250 kref_put(&hvcsd->kref, destroy_hvcs_struct);
1251 return;
1252 } else if (hvcsd->open_count < 0) {
1253 printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
1254 " is missmanaged.\n",
1255 hvcsd->vdev->unit_address, hvcsd->open_count);
1258 spin_unlock_irqrestore(&hvcsd->lock, flags);
1259 kref_put(&hvcsd->kref, destroy_hvcs_struct);
1262 static void hvcs_hangup(struct tty_struct * tty)
1264 struct hvcs_struct *hvcsd = tty->driver_data;
1265 unsigned long flags;
1266 int temp_open_count;
1267 int irq = NO_IRQ;
1269 spin_lock_irqsave(&hvcsd->lock, flags);
1270 /* Preserve this so that we know how many kref refs to put */
1271 temp_open_count = hvcsd->open_count;
1274 * Don't kref put inside the spinlock because the destruction
1275 * callback may use the spinlock and it may get called before the
1276 * spinlock has been released.
1278 vio_disable_interrupts(hvcsd->vdev);
1280 hvcsd->todo_mask = 0;
1282 /* I don't think the tty needs the hvcs_struct pointer after a hangup */
1283 hvcsd->tty->driver_data = NULL;
1284 hvcsd->tty = NULL;
1286 hvcsd->open_count = 0;
1288 /* This will drop any buffered data on the floor which is OK in a hangup
1289 * scenario. */
1290 memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1291 hvcsd->chars_in_buffer = 0;
1293 irq = hvcsd->vdev->irq;
1295 spin_unlock_irqrestore(&hvcsd->lock, flags);
1297 free_irq(irq, hvcsd);
1300 * We need to kref_put() for every open_count we have since the
1301 * tty_hangup() function doesn't invoke a close per open connection on a
1302 * non-console device.
1304 while(temp_open_count) {
1305 --temp_open_count;
1307 * The final put will trigger destruction of the hvcs_struct.
1308 * NOTE: If this hangup was signaled from user space then the
1309 * final put will never happen.
1311 kref_put(&hvcsd->kref, destroy_hvcs_struct);
1316 * NOTE: This is almost always from_user since user level apps interact with the
1317 * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1318 * hvcs_remove (which removes the target device and executes tty_hangup()) that
1319 * tty_hangup will allow hvcs_write time to complete execution before it
1320 * terminates our device.
1322 static int hvcs_write(struct tty_struct *tty,
1323 const unsigned char *buf, int count)
1325 struct hvcs_struct *hvcsd = tty->driver_data;
1326 unsigned int unit_address;
1327 const unsigned char *charbuf;
1328 unsigned long flags;
1329 int total_sent = 0;
1330 int tosend = 0;
1331 int result = 0;
1334 * If they don't check the return code off of their open they may
1335 * attempt this even if there is no connected device.
1337 if (!hvcsd)
1338 return -ENODEV;
1340 /* Reasonable size to prevent user level flooding */
1341 if (count > HVCS_MAX_FROM_USER) {
1342 printk(KERN_WARNING "HVCS write: count being truncated to"
1343 " HVCS_MAX_FROM_USER.\n");
1344 count = HVCS_MAX_FROM_USER;
1347 charbuf = buf;
1349 spin_lock_irqsave(&hvcsd->lock, flags);
1352 * Somehow an open succeeded but the device was removed or the
1353 * connection terminated between the vty-server and partner vty during
1354 * the middle of a write operation? This is a crummy place to do this
1355 * but we want to keep it all in the spinlock.
1357 if (hvcsd->open_count <= 0) {
1358 spin_unlock_irqrestore(&hvcsd->lock, flags);
1359 return -ENODEV;
1362 unit_address = hvcsd->vdev->unit_address;
1364 while (count > 0) {
1365 tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1367 * No more space, this probably means that the last call to
1368 * hvcs_write() didn't succeed and the buffer was filled up.
1370 if (!tosend)
1371 break;
1373 memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1374 &charbuf[total_sent],
1375 tosend);
1377 hvcsd->chars_in_buffer += tosend;
1379 result = 0;
1382 * If this is true then we don't want to try writing to the
1383 * hypervisor because that is the kernel_threads job now. We'll
1384 * just add to the buffer.
1386 if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1387 /* won't send partial writes */
1388 result = hvc_put_chars(unit_address,
1389 &hvcsd->buffer[0],
1390 hvcsd->chars_in_buffer);
1393 * Since we know we have enough room in hvcsd->buffer for
1394 * tosend we record that it was sent regardless of whether the
1395 * hypervisor actually took it because we have it buffered.
1397 total_sent+=tosend;
1398 count-=tosend;
1399 if (result == 0) {
1400 hvcsd->todo_mask |= HVCS_TRY_WRITE;
1401 hvcs_kick();
1402 break;
1405 hvcsd->chars_in_buffer = 0;
1407 * Test after the chars_in_buffer reset otherwise this could
1408 * deadlock our writes if hvc_put_chars fails.
1410 if (result < 0)
1411 break;
1414 spin_unlock_irqrestore(&hvcsd->lock, flags);
1416 if (result == -1)
1417 return -EIO;
1418 else
1419 return total_sent;
1423 * This is really asking how much can we guarantee that we can send or that we
1424 * absolutely WILL BUFFER if we can't send it. This driver MUST honor the
1425 * return value, hence the reason for hvcs_struct buffering.
1427 static int hvcs_write_room(struct tty_struct *tty)
1429 struct hvcs_struct *hvcsd = tty->driver_data;
1431 if (!hvcsd || hvcsd->open_count <= 0)
1432 return 0;
1434 return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1437 static int hvcs_chars_in_buffer(struct tty_struct *tty)
1439 struct hvcs_struct *hvcsd = tty->driver_data;
1441 return hvcsd->chars_in_buffer;
1444 static const struct tty_operations hvcs_ops = {
1445 .open = hvcs_open,
1446 .close = hvcs_close,
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,
1455 static int hvcs_alloc_index_list(int n)
1457 int i;
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;
1468 static void hvcs_free_index_list(void)
1470 /* Paranoia check to be thorough. */
1471 kfree(hvcs_index_list);
1472 hvcs_index_list = NULL;
1473 hvcs_index_count = 0;
1476 static int __devinit hvcs_initialize(void)
1478 int rc, num_ttys_to_alloc;
1480 mutex_lock(&hvcs_init_mutex);
1481 if (hvcs_task) {
1482 mutex_unlock(&hvcs_init_mutex);
1483 return 0;
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;
1493 hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
1494 if (!hvcs_tty_driver)
1495 return -ENOMEM;
1497 if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1498 rc = -ENOMEM;
1499 goto index_fail;
1502 hvcs_tty_driver->owner = THIS_MODULE;
1504 hvcs_tty_driver->driver_name = hvcs_driver_name;
1505 hvcs_tty_driver->name = hvcs_device_node;
1508 * We'll let the system assign us a major number, indicated by leaving
1509 * it blank.
1512 hvcs_tty_driver->minor_start = HVCS_MINOR_START;
1513 hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
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.
1520 hvcs_tty_driver->init_termios = hvcs_tty_termios;
1521 hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
1523 tty_set_operations(hvcs_tty_driver, &hvcs_ops);
1526 * The following call will result in sysfs entries that denote the
1527 * dynamically assigned major and minor numbers for our devices.
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;
1535 hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
1536 if (!hvcs_pi_buff) {
1537 rc = -ENOMEM;
1538 goto buff_alloc_fail;
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;
1547 mutex_unlock(&hvcs_init_mutex);
1548 return 0;
1550 kthread_fail:
1551 kfree(hvcs_pi_buff);
1552 buff_alloc_fail:
1553 tty_unregister_driver(hvcs_tty_driver);
1554 register_fail:
1555 hvcs_free_index_list();
1556 index_fail:
1557 put_tty_driver(hvcs_tty_driver);
1558 hvcs_tty_driver = NULL;
1559 mutex_unlock(&hvcs_init_mutex);
1560 return rc;
1563 static int __init hvcs_module_init(void)
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;
1571 pr_info("HVCS: Driver registered.\n");
1573 /* This needs to be done AFTER the vio_register_driver() call or else
1574 * the kobjects won't be initialized properly.
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);
1580 return 0;
1583 static void __exit hvcs_module_exit(void)
1586 * This driver receives hvcs_remove callbacks for each device upon
1587 * module removal.
1589 vio_unregister_driver(&hvcs_vio_driver);
1590 if (!hvcs_task)
1591 return;
1594 * This synchronous operation will wake the khvcsd kthread if it is
1595 * asleep and will return when khvcsd has terminated.
1597 kthread_stop(hvcs_task);
1599 spin_lock(&hvcs_pi_lock);
1600 kfree(hvcs_pi_buff);
1601 hvcs_pi_buff = NULL;
1602 spin_unlock(&hvcs_pi_lock);
1604 driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
1606 tty_unregister_driver(hvcs_tty_driver);
1608 hvcs_free_index_list();
1610 put_tty_driver(hvcs_tty_driver);
1612 printk(KERN_INFO "HVCS: driver module removed.\n");
1615 module_init(hvcs_module_init);
1616 module_exit(hvcs_module_exit);