Linux 4.1.16
[linux/fpc-iii.git] / drivers / tty / hvc / hvcs.c
blob81ff7e1bfb1a82ac68dd33d760b84f7edff4e9b8
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 struct tty_port port;
265 spinlock_t lock;
268 * This index identifies this hvcs device as the complement to a
269 * specific tty index.
271 unsigned int index;
274 * Used to tell the driver kernel_thread what operations need to take
275 * place upon this hvcs_struct instance.
277 int todo_mask;
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()].
287 char buffer[HVCS_BUFF_LEN];
288 int chars_in_buffer;
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.
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;
304 static LIST_HEAD(hvcs_structs);
305 static DEFINE_SPINLOCK(hvcs_structs_lock);
306 static DEFINE_MUTEX(hvcs_init_mutex);
308 static void hvcs_unthrottle(struct tty_struct *tty);
309 static void hvcs_throttle(struct tty_struct *tty);
310 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
312 static int hvcs_write(struct tty_struct *tty,
313 const unsigned char *buf, int count);
314 static int hvcs_write_room(struct tty_struct *tty);
315 static int hvcs_chars_in_buffer(struct tty_struct *tty);
317 static int hvcs_has_pi(struct hvcs_struct *hvcsd);
318 static void hvcs_set_pi(struct hvcs_partner_info *pi,
319 struct hvcs_struct *hvcsd);
320 static int hvcs_get_pi(struct hvcs_struct *hvcsd);
321 static int hvcs_rescan_devices_list(void);
323 static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
324 static void hvcs_partner_free(struct hvcs_struct *hvcsd);
326 static int hvcs_enable_device(struct hvcs_struct *hvcsd,
327 uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
329 static int hvcs_open(struct tty_struct *tty, struct file *filp);
330 static void hvcs_close(struct tty_struct *tty, struct file *filp);
331 static void hvcs_hangup(struct tty_struct * tty);
333 static int hvcs_probe(struct vio_dev *dev,
334 const struct vio_device_id *id);
335 static int hvcs_remove(struct vio_dev *dev);
336 static int __init hvcs_module_init(void);
337 static void __exit hvcs_module_exit(void);
338 static int hvcs_initialize(void);
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)
345 static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
347 return dev_get_drvdata(&viod->dev);
349 /* The sysfs interface for the driver and devices */
351 static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
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;
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;
363 static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
365 static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
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;
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;
377 static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
379 static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
380 size_t count)
383 * Don't need this feature at the present time because firmware doesn't
384 * yet support multiple partners.
386 printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
387 return -EPERM;
390 static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
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;
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;
403 static DEVICE_ATTR(current_vty,
404 S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
406 static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
407 size_t count)
409 struct vio_dev *viod = to_vio_dev(dev);
410 struct hvcs_struct *hvcsd = from_vio_dev(viod);
411 unsigned long flags;
413 /* writing a '0' to this sysfs entry will result in the disconnect. */
414 if (simple_strtol(buf, NULL, 0) != 0)
415 return -EINVAL;
417 spin_lock_irqsave(&hvcsd->lock, flags);
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;
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;
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);
440 spin_unlock_irqrestore(&hvcsd->lock, flags);
441 return count;
444 static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
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;
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;
456 static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
457 hvcs_vterm_state_show, hvcs_vterm_state_store);
459 static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
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;
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;
472 static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
474 static 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,
483 static struct attribute_group hvcs_attr_group = {
484 .attrs = hvcs_attrs,
487 static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
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);
493 static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
494 size_t count)
496 if ((simple_strtol(buf, NULL, 0) != 1)
497 && (hvcs_rescan_status != 0))
498 return -EINVAL;
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;
508 static DRIVER_ATTR(rescan,
509 S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
511 static void hvcs_kick(void)
513 hvcs_kicked = 1;
514 wmb();
515 wake_up_process(hvcs_task);
518 static void hvcs_unthrottle(struct tty_struct *tty)
520 struct hvcs_struct *hvcsd = tty->driver_data;
521 unsigned long flags;
523 spin_lock_irqsave(&hvcsd->lock, flags);
524 hvcsd->todo_mask |= HVCS_SCHED_READ;
525 spin_unlock_irqrestore(&hvcsd->lock, flags);
526 hvcs_kick();
529 static void hvcs_throttle(struct tty_struct *tty)
531 struct hvcs_struct *hvcsd = tty->driver_data;
532 unsigned long flags;
534 spin_lock_irqsave(&hvcsd->lock, flags);
535 vio_disable_interrupts(hvcsd->vdev);
536 spin_unlock_irqrestore(&hvcsd->lock, flags);
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.
544 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
546 struct hvcs_struct *hvcsd = dev_instance;
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();
554 return IRQ_HANDLED;
557 /* This function must be called with the hvcsd->lock held */
558 static void hvcs_try_write(struct hvcs_struct *hvcsd)
560 uint32_t unit_address = hvcsd->vdev->unit_address;
561 struct tty_struct *tty = hvcsd->port.tty;
562 int sent;
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(); */
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.
581 if (tty) {
582 tty_wakeup(tty);
588 static int hvcs_io(struct hvcs_struct *hvcsd)
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;
596 spin_lock_irqsave(&hvcsd->lock, flags);
598 unit_address = hvcsd->vdev->unit_address;
599 tty = hvcsd->port.tty;
601 hvcs_try_write(hvcsd);
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;
609 /* remove the read masks */
610 hvcsd->todo_mask &= ~(HVCS_READ_MASK);
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);
619 /* Give the TTY time to process the data we just sent. */
620 if (got)
621 hvcsd->todo_mask |= HVCS_QUICK_READ;
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);
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);
635 return hvcsd->todo_mask;
637 bail:
638 spin_unlock_irqrestore(&hvcsd->lock, flags);
639 return hvcsd->todo_mask;
642 static int khvcsd(void *unused)
644 struct hvcs_struct *hvcsd;
645 int hvcs_todo_mask;
647 __set_current_state(TASK_RUNNING);
649 do {
650 hvcs_todo_mask = 0;
651 hvcs_kicked = 0;
652 wmb();
654 spin_lock(&hvcs_structs_lock);
655 list_for_each_entry(hvcsd, &hvcs_structs, next) {
656 hvcs_todo_mask |= hvcs_io(hvcsd);
658 spin_unlock(&hvcs_structs_lock);
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.
665 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
666 yield();
667 continue;
670 set_current_state(TASK_INTERRUPTIBLE);
671 if (!hvcs_kicked)
672 schedule();
673 __set_current_state(TASK_RUNNING);
674 } while (!kthread_should_stop());
676 return 0;
679 static struct vio_device_id hvcs_driver_table[] = {
680 {"serial-server", "hvterm2"},
681 { "", "" }
683 MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
685 static void hvcs_return_index(int index)
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;
698 static void hvcs_destruct_port(struct tty_port *p)
700 struct hvcs_struct *hvcsd = container_of(p, struct hvcs_struct, port);
701 struct vio_dev *vdev;
702 unsigned long flags;
704 spin_lock(&hvcs_structs_lock);
705 spin_lock_irqsave(&hvcsd->lock, flags);
707 /* the list_del poisons the pointers */
708 list_del(&(hvcsd->next));
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);
718 printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
719 hvcsd->vdev->unit_address);
721 vdev = hvcsd->vdev;
722 hvcsd->vdev = NULL;
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);
729 spin_unlock_irqrestore(&hvcsd->lock, flags);
730 spin_unlock(&hvcs_structs_lock);
732 sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
734 kfree(hvcsd);
737 static const struct tty_port_operations hvcs_port_ops = {
738 .destruct = hvcs_destruct_port,
741 static int hvcs_get_index(void)
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;
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;
756 return -1;
759 static int hvcs_probe(
760 struct vio_dev *dev,
761 const struct vio_device_id *id)
763 struct hvcs_struct *hvcsd;
764 int index, rc;
765 int retval;
767 if (!dev || !id) {
768 printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
769 return -EPERM;
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;
779 /* early to avoid cleanup on failure */
780 index = hvcs_get_index();
781 if (index < 0) {
782 return -EFAULT;
785 hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
786 if (!hvcsd)
787 return -ENODEV;
789 tty_port_init(&hvcsd->port);
790 hvcsd->port.ops = &hvcs_port_ops;
791 spin_lock_init(&hvcsd->lock);
793 hvcsd->vdev = dev;
794 dev_set_drvdata(&dev->dev, hvcsd);
796 hvcsd->index = index;
798 /* hvcsd->index = ++hvcs_struct_count; */
799 hvcsd->chars_in_buffer = 0;
800 hvcsd->todo_mask = 0;
801 hvcsd->connected = 0;
804 * This will populate the hvcs_struct's partner info fields for the
805 * first time.
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);
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.
818 spin_lock(&hvcs_structs_lock);
819 list_add_tail(&(hvcsd->next), &hvcs_structs);
820 spin_unlock(&hvcs_structs_lock);
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;
829 printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
832 * DON'T enable interrupts here because there is no user to receive the
833 * data.
835 return 0;
838 static int hvcs_remove(struct vio_dev *dev)
840 struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
841 unsigned long flags;
842 struct tty_struct *tty;
844 if (!hvcsd)
845 return -ENODEV;
847 /* By this time the vty-server won't be getting any more interrupts */
849 spin_lock_irqsave(&hvcsd->lock, flags);
851 tty = hvcsd->port.tty;
853 spin_unlock_irqrestore(&hvcsd->lock, flags);
856 * Let the last holder of this object cause it to be removed, which
857 * would probably be tty_hangup below.
859 tty_port_put(&hvcsd->port);
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.
866 if (tty)
867 tty_hangup(tty);
869 printk(KERN_INFO "HVCS: vty-server@%X removed from the"
870 " vio bus.\n", dev->unit_address);
871 return 0;
874 static 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,
881 /* Only called from hvcs_get_pi please */
882 static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
884 hvcsd->p_unit_address = pi->unit_address;
885 hvcsd->p_partition_ID = pi->partition_ID;
887 /* copy the null-term char too */
888 strlcpy(&hvcsd->p_location_code[0],
889 &pi->location_code[0], sizeof(hvcsd->p_location_code));
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.
903 * This function must be called with the hvcsd->lock held.
905 static int hvcs_get_pi(struct hvcs_struct *hvcsd)
907 struct hvcs_partner_info *pi;
908 uint32_t unit_address = hvcsd->vdev->unit_address;
909 struct list_head head;
910 int retval;
912 spin_lock(&hvcs_pi_lock);
913 if (!hvcs_pi_buff) {
914 spin_unlock(&hvcs_pi_lock);
915 return -EFAULT;
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;
925 /* nixes the values if the partner vty went away */
926 hvcsd->p_unit_address = 0;
927 hvcsd->p_partition_ID = 0;
929 list_for_each_entry(pi, &head, node)
930 hvcs_set_pi(pi, hvcsd);
932 hvcs_free_partner_info(&head);
933 return 0;
937 * This function is executed by the driver "rescan" sysfs entry. It shouldn't
938 * be executed elsewhere, in order to prevent deadlock issues.
940 static int hvcs_rescan_devices_list(void)
942 struct hvcs_struct *hvcsd;
943 unsigned long flags;
945 spin_lock(&hvcs_structs_lock);
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);
953 spin_unlock(&hvcs_structs_lock);
955 return 0;
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.
963 static int hvcs_has_pi(struct hvcs_struct *hvcsd)
965 if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
966 return 0;
967 return 1;
971 * NOTE: It is possible that the super admin removed a partner vty and then
972 * added a different vty as the new partner.
974 * This function must be called with the hvcsd->lock held.
976 static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
978 int retval;
979 unsigned int unit_address = hvcsd->vdev->unit_address;
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.
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;
998 * As per the spec re-get the pi and try again if -EINVAL after the
999 * first connection attempt.
1001 if (hvcs_get_pi(hvcsd))
1002 return -ENOMEM;
1004 if (!hvcs_has_pi(hvcsd))
1005 return -ENODEV;
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;
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.
1021 printk(KERN_INFO "HVCS: vty-server or partner"
1022 " vty is busy. Try again later.\n");
1023 return -EBUSY;
1026 /* This function must be called with the hvcsd->lock held */
1027 static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1029 int retval;
1030 do {
1031 retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1032 } while (retval == -EBUSY);
1033 hvcsd->connected = 0;
1036 /* This helper function must be called WITHOUT the hvcsd->lock held */
1037 static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1038 unsigned int irq, struct vio_dev *vdev)
1040 unsigned long flags;
1041 int rc;
1044 * It is possible that the vty-server was removed between the time that
1045 * the conn was registered and now.
1047 if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
1048 0, "ibmhvcs", hvcsd))) {
1050 * It is possible the vty-server was removed after the irq was
1051 * requested but before we have time to enable interrupts.
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);
1060 } else
1061 printk(KERN_ERR "HVCS: irq req failed for"
1062 " vty-server@%X.\n", unit_address);
1064 spin_lock_irqsave(&hvcsd->lock, flags);
1065 hvcs_partner_free(hvcsd);
1066 spin_unlock_irqrestore(&hvcsd->lock, flags);
1068 return rc;
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.
1076 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1077 * calling this function or you will get deadlock.
1079 static struct hvcs_struct *hvcs_get_by_index(int index)
1081 struct hvcs_struct *hvcsd;
1082 unsigned long flags;
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;
1093 spin_unlock_irqrestore(&hvcsd->lock, flags);
1095 spin_unlock(&hvcs_structs_lock);
1097 return NULL;
1100 static int hvcs_install(struct tty_driver *driver, struct tty_struct *tty)
1102 struct hvcs_struct *hvcsd;
1103 struct vio_dev *vdev;
1104 unsigned long unit_address, flags;
1105 unsigned int irq;
1106 int retval;
1109 * Is there a vty-server that shares the same index?
1110 * This function increments the kref index.
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;
1119 spin_lock_irqsave(&hvcsd->lock, flags);
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;
1130 hvcsd->port.count = 0;
1131 hvcsd->port.tty = tty;
1132 tty->driver_data = hvcsd;
1134 memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1137 * Save these in the spinlock for the enable operations that need them
1138 * outside of the spinlock.
1140 irq = hvcsd->vdev->irq;
1141 vdev = hvcsd->vdev;
1142 unit_address = hvcsd->vdev->unit_address;
1144 hvcsd->todo_mask |= HVCS_SCHED_READ;
1145 spin_unlock_irqrestore(&hvcsd->lock, flags);
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.
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;
1157 retval = tty_port_install(&hvcsd->port, driver, tty);
1158 if (retval)
1159 goto err_irq;
1161 return 0;
1162 err_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);
1167 err_put:
1168 tty_port_put(&hvcsd->port);
1170 return retval;
1174 * This is invoked via the tty_open interface when a user app connects to the
1175 * /dev node.
1177 static int hvcs_open(struct tty_struct *tty, struct file *filp)
1179 struct hvcs_struct *hvcsd = tty->driver_data;
1180 unsigned long flags;
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);
1187 hvcs_kick();
1189 printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1190 hvcsd->vdev->unit_address );
1192 return 0;
1195 static void hvcs_close(struct tty_struct *tty, struct file *filp)
1197 struct hvcs_struct *hvcsd;
1198 unsigned long flags;
1199 int irq;
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.
1205 if (tty_hung_up_p(filp))
1206 return;
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.
1213 if (!tty->driver_data)
1214 return;
1216 hvcsd = tty->driver_data;
1218 spin_lock_irqsave(&hvcsd->lock, flags);
1219 if (--hvcsd->port.count == 0) {
1221 vio_disable_interrupts(hvcsd->vdev);
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.
1228 hvcsd->port.tty = NULL;
1230 irq = hvcsd->vdev->irq;
1231 spin_unlock_irqrestore(&hvcsd->lock, flags);
1233 tty_wait_until_sent_from_close(tty, HVCS_CLOSE_WAIT);
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.
1240 tty->driver_data = NULL;
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);
1250 spin_unlock_irqrestore(&hvcsd->lock, flags);
1253 static void hvcs_cleanup(struct tty_struct * tty)
1255 struct hvcs_struct *hvcsd = tty->driver_data;
1257 tty_port_put(&hvcsd->port);
1260 static void hvcs_hangup(struct tty_struct * tty)
1262 struct hvcs_struct *hvcsd = tty->driver_data;
1263 unsigned long flags;
1264 int temp_open_count;
1265 int irq;
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;
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.
1276 vio_disable_interrupts(hvcsd->vdev);
1278 hvcsd->todo_mask = 0;
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;
1284 hvcsd->port.count = 0;
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;
1291 irq = hvcsd->vdev->irq;
1293 spin_unlock_irqrestore(&hvcsd->lock, flags);
1295 free_irq(irq, hvcsd);
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.
1302 while(temp_open_count) {
1303 --temp_open_count;
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.
1309 tty_port_put(&hvcsd->port);
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.
1320 static int hvcs_write(struct tty_struct *tty,
1321 const unsigned char *buf, int count)
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;
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.
1335 if (!hvcsd)
1336 return -ENODEV;
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;
1345 charbuf = buf;
1347 spin_lock_irqsave(&hvcsd->lock, flags);
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.
1355 if (hvcsd->port.count <= 0) {
1356 spin_unlock_irqrestore(&hvcsd->lock, flags);
1357 return -ENODEV;
1360 unit_address = hvcsd->vdev->unit_address;
1362 while (count > 0) {
1363 tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1365 * No more space, this probably means that the last call to
1366 * hvcs_write() didn't succeed and the buffer was filled up.
1368 if (!tosend)
1369 break;
1371 memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1372 &charbuf[total_sent],
1373 tosend);
1375 hvcsd->chars_in_buffer += tosend;
1377 result = 0;
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.
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);
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.
1395 total_sent+=tosend;
1396 count-=tosend;
1397 if (result == 0) {
1398 hvcsd->todo_mask |= HVCS_TRY_WRITE;
1399 hvcs_kick();
1400 break;
1403 hvcsd->chars_in_buffer = 0;
1405 * Test after the chars_in_buffer reset otherwise this could
1406 * deadlock our writes if hvc_put_chars fails.
1408 if (result < 0)
1409 break;
1412 spin_unlock_irqrestore(&hvcsd->lock, flags);
1414 if (result == -1)
1415 return -EIO;
1416 else
1417 return total_sent;
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.
1425 static int hvcs_write_room(struct tty_struct *tty)
1427 struct hvcs_struct *hvcsd = tty->driver_data;
1429 if (!hvcsd || hvcsd->port.count <= 0)
1430 return 0;
1432 return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1435 static int hvcs_chars_in_buffer(struct tty_struct *tty)
1437 struct hvcs_struct *hvcsd = tty->driver_data;
1439 return hvcsd->chars_in_buffer;
1442 static 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,
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 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 mutex_unlock(&hvcs_init_mutex);
1496 return -ENOMEM;
1499 if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1500 rc = -ENOMEM;
1501 goto index_fail;
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 = (unsigned long *) __get_free_page(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 free_page((unsigned long)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("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 free_page((unsigned long)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);