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Timur Tabidcd83aa2011-07-08 19:06:12 -05001/* ePAPR hypervisor byte channel device driver
2 *
3 * Copyright 2009-2011 Freescale Semiconductor, Inc.
4 *
5 * Author: Timur Tabi <timur@freescale.com>
6 *
7 * This file is licensed under the terms of the GNU General Public License
8 * version 2. This program is licensed "as is" without any warranty of any
9 * kind, whether express or implied.
10 *
11 * This driver support three distinct interfaces, all of which are related to
12 * ePAPR hypervisor byte channels.
13 *
14 * 1) An early-console (udbg) driver. This provides early console output
15 * through a byte channel. The byte channel handle must be specified in a
16 * Kconfig option.
17 *
18 * 2) A normal console driver. Output is sent to the byte channel designated
19 * for stdout in the device tree. The console driver is for handling kernel
20 * printk calls.
21 *
22 * 3) A tty driver, which is used to handle user-space input and output. The
23 * byte channel used for the console is designated as the default tty.
24 */
25
26#include <linux/module.h>
27#include <linux/init.h>
28#include <linux/slab.h>
29#include <linux/err.h>
30#include <linux/interrupt.h>
31#include <linux/fs.h>
32#include <linux/poll.h>
33#include <asm/epapr_hcalls.h>
34#include <linux/of.h>
35#include <linux/platform_device.h>
36#include <linux/cdev.h>
37#include <linux/console.h>
38#include <linux/tty.h>
39#include <linux/tty_flip.h>
40#include <linux/circ_buf.h>
41#include <asm/udbg.h>
42
43/* The size of the transmit circular buffer. This must be a power of two. */
44#define BUF_SIZE 2048
45
46/* Per-byte channel private data */
47struct ehv_bc_data {
48 struct device *dev;
49 struct tty_port port;
50 uint32_t handle;
51 unsigned int rx_irq;
52 unsigned int tx_irq;
53
54 spinlock_t lock; /* lock for transmit buffer */
55 unsigned char buf[BUF_SIZE]; /* transmit circular buffer */
56 unsigned int head; /* circular buffer head */
57 unsigned int tail; /* circular buffer tail */
58
59 int tx_irq_enabled; /* true == TX interrupt is enabled */
60};
61
62/* Array of byte channel objects */
63static struct ehv_bc_data *bcs;
64
65/* Byte channel handle for stdout (and stdin), taken from device tree */
66static unsigned int stdout_bc;
67
68/* Virtual IRQ for the byte channel handle for stdin, taken from device tree */
69static unsigned int stdout_irq;
70
71/**************************** SUPPORT FUNCTIONS ****************************/
72
73/*
74 * Enable the transmit interrupt
75 *
76 * Unlike a serial device, byte channels have no mechanism for disabling their
77 * own receive or transmit interrupts. To emulate that feature, we toggle
78 * the IRQ in the kernel.
79 *
80 * We cannot just blindly call enable_irq() or disable_irq(), because these
81 * calls are reference counted. This means that we cannot call enable_irq()
82 * if interrupts are already enabled. This can happen in two situations:
83 *
84 * 1. The tty layer makes two back-to-back calls to ehv_bc_tty_write()
85 * 2. A transmit interrupt occurs while executing ehv_bc_tx_dequeue()
86 *
87 * To work around this, we keep a flag to tell us if the IRQ is enabled or not.
88 */
89static void enable_tx_interrupt(struct ehv_bc_data *bc)
90{
91 if (!bc->tx_irq_enabled) {
92 enable_irq(bc->tx_irq);
93 bc->tx_irq_enabled = 1;
94 }
95}
96
97static void disable_tx_interrupt(struct ehv_bc_data *bc)
98{
99 if (bc->tx_irq_enabled) {
100 disable_irq_nosync(bc->tx_irq);
101 bc->tx_irq_enabled = 0;
102 }
103}
104
105/*
106 * find the byte channel handle to use for the console
107 *
108 * The byte channel to be used for the console is specified via a "stdout"
109 * property in the /chosen node.
110 *
111 * For compatible with legacy device trees, we also look for a "stdout" alias.
112 */
113static int find_console_handle(void)
114{
115 struct device_node *np, *np2;
116 const char *sprop = NULL;
117 const uint32_t *iprop;
118
119 np = of_find_node_by_path("/chosen");
120 if (np)
121 sprop = of_get_property(np, "stdout-path", NULL);
122
123 if (!np || !sprop) {
124 of_node_put(np);
125 np = of_find_node_by_name(NULL, "aliases");
126 if (np)
127 sprop = of_get_property(np, "stdout", NULL);
128 }
129
130 if (!sprop) {
131 of_node_put(np);
132 return 0;
133 }
134
135 /* We don't care what the aliased node is actually called. We only
136 * care if it's compatible with "epapr,hv-byte-channel", because that
137 * indicates that it's a byte channel node. We use a temporary
138 * variable, 'np2', because we can't release 'np' until we're done with
139 * 'sprop'.
140 */
141 np2 = of_find_node_by_path(sprop);
142 of_node_put(np);
143 np = np2;
144 if (!np) {
145 pr_warning("ehv-bc: stdout node '%s' does not exist\n", sprop);
146 return 0;
147 }
148
149 /* Is it a byte channel? */
150 if (!of_device_is_compatible(np, "epapr,hv-byte-channel")) {
151 of_node_put(np);
152 return 0;
153 }
154
155 stdout_irq = irq_of_parse_and_map(np, 0);
156 if (stdout_irq == NO_IRQ) {
157 pr_err("ehv-bc: no 'interrupts' property in %s node\n", sprop);
158 of_node_put(np);
159 return 0;
160 }
161
162 /*
163 * The 'hv-handle' property contains the handle for this byte channel.
164 */
165 iprop = of_get_property(np, "hv-handle", NULL);
166 if (!iprop) {
167 pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
168 np->name);
169 of_node_put(np);
170 return 0;
171 }
172 stdout_bc = be32_to_cpu(*iprop);
173
174 of_node_put(np);
175 return 1;
176}
177
178/*************************** EARLY CONSOLE DRIVER ***************************/
179
180#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
181
182/*
183 * send a byte to a byte channel, wait if necessary
184 *
185 * This function sends a byte to a byte channel, and it waits and
186 * retries if the byte channel is full. It returns if the character
187 * has been sent, or if some error has occurred.
188 *
189 */
190static void byte_channel_spin_send(const char data)
191{
192 int ret, count;
193
194 do {
195 count = 1;
196 ret = ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
197 &count, &data);
198 } while (ret == EV_EAGAIN);
199}
200
201/*
202 * The udbg subsystem calls this function to display a single character.
203 * We convert CR to a CR/LF.
204 */
205static void ehv_bc_udbg_putc(char c)
206{
207 if (c == '\n')
208 byte_channel_spin_send('\r');
209
210 byte_channel_spin_send(c);
211}
212
213/*
214 * early console initialization
215 *
216 * PowerPC kernels support an early printk console, also known as udbg.
217 * This function must be called via the ppc_md.init_early function pointer.
218 * At this point, the device tree has been unflattened, so we can obtain the
219 * byte channel handle for stdout.
220 *
221 * We only support displaying of characters (putc). We do not support
222 * keyboard input.
223 */
224void __init udbg_init_ehv_bc(void)
225{
226 unsigned int rx_count, tx_count;
227 unsigned int ret;
228
Timur Tabidcd83aa2011-07-08 19:06:12 -0500229 /* Verify the byte channel handle */
230 ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
231 &rx_count, &tx_count);
232 if (ret)
233 return;
234
235 udbg_putc = ehv_bc_udbg_putc;
236 register_early_udbg_console();
237
238 udbg_printf("ehv-bc: early console using byte channel handle %u\n",
239 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
240}
241
242#endif
243
244/****************************** CONSOLE DRIVER ******************************/
245
246static struct tty_driver *ehv_bc_driver;
247
248/*
249 * Byte channel console sending worker function.
250 *
251 * For consoles, if the output buffer is full, we should just spin until it
252 * clears.
253 */
254static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,
255 unsigned int count)
256{
257 unsigned int len;
258 int ret = 0;
259
260 while (count) {
261 len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);
262 do {
263 ret = ev_byte_channel_send(handle, &len, s);
264 } while (ret == EV_EAGAIN);
265 count -= len;
266 s += len;
267 }
268
269 return ret;
270}
271
272/*
273 * write a string to the console
274 *
275 * This function gets called to write a string from the kernel, typically from
276 * a printk(). This function spins until all data is written.
277 *
278 * We copy the data to a temporary buffer because we need to insert a \r in
279 * front of every \n. It's more efficient to copy the data to the buffer than
280 * it is to make multiple hcalls for each character or each newline.
281 */
282static void ehv_bc_console_write(struct console *co, const char *s,
283 unsigned int count)
284{
Timur Tabidcd83aa2011-07-08 19:06:12 -0500285 char s2[EV_BYTE_CHANNEL_MAX_BYTES];
286 unsigned int i, j = 0;
287 char c;
288
289 for (i = 0; i < count; i++) {
290 c = *s++;
291
292 if (c == '\n')
293 s2[j++] = '\r';
294
295 s2[j++] = c;
296 if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {
Timur Tabifd01a7a2011-09-22 20:33:13 -0500297 if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j))
Timur Tabidcd83aa2011-07-08 19:06:12 -0500298 return;
299 j = 0;
300 }
301 }
302
303 if (j)
Timur Tabifd01a7a2011-09-22 20:33:13 -0500304 ehv_bc_console_byte_channel_send(stdout_bc, s2, j);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500305}
306
307/*
308 * When /dev/console is opened, the kernel iterates the console list looking
309 * for one with ->device and then calls that method. On success, it expects
310 * the passed-in int* to contain the minor number to use.
311 */
312static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)
313{
314 *index = co->index;
315
316 return ehv_bc_driver;
317}
318
319static struct console ehv_bc_console = {
320 .name = "ttyEHV",
321 .write = ehv_bc_console_write,
322 .device = ehv_bc_console_device,
323 .flags = CON_PRINTBUFFER | CON_ENABLED,
324};
325
326/*
327 * Console initialization
328 *
329 * This is the first function that is called after the device tree is
330 * available, so here is where we determine the byte channel handle and IRQ for
331 * stdout/stdin, even though that information is used by the tty and character
332 * drivers.
333 */
334static int __init ehv_bc_console_init(void)
335{
336 if (!find_console_handle()) {
337 pr_debug("ehv-bc: stdout is not a byte channel\n");
338 return -ENODEV;
339 }
340
341#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
342 /* Print a friendly warning if the user chose the wrong byte channel
343 * handle for udbg.
344 */
345 if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)
346 pr_warning("ehv-bc: udbg handle %u is not the stdout handle\n",
347 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
348#endif
349
Timur Tabidcd83aa2011-07-08 19:06:12 -0500350 /* add_preferred_console() must be called before register_console(),
351 otherwise it won't work. However, we don't want to enumerate all the
352 byte channels here, either, since we only care about one. */
353
354 add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);
355 register_console(&ehv_bc_console);
356
357 pr_info("ehv-bc: registered console driver for byte channel %u\n",
358 stdout_bc);
359
360 return 0;
361}
362console_initcall(ehv_bc_console_init);
363
364/******************************** TTY DRIVER ********************************/
365
366/*
367 * byte channel receive interupt handler
368 *
369 * This ISR is called whenever data is available on a byte channel.
370 */
371static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
372{
373 struct ehv_bc_data *bc = data;
Timur Tabidcd83aa2011-07-08 19:06:12 -0500374 unsigned int rx_count, tx_count, len;
375 int count;
376 char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
377 int ret;
378
Timur Tabidcd83aa2011-07-08 19:06:12 -0500379 /* Find out how much data needs to be read, and then ask the TTY layer
380 * if it can handle that much. We want to ensure that every byte we
381 * read from the byte channel will be accepted by the TTY layer.
382 */
383 ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);
Jiri Slaby227434f2013-01-03 15:53:01 +0100384 count = tty_buffer_request_room(&bc->port, rx_count);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500385
386 /* 'count' is the maximum amount of data the TTY layer can accept at
387 * this time. However, during testing, I was never able to get 'count'
388 * to be less than 'rx_count'. I'm not sure whether I'm calling it
389 * correctly.
390 */
391
392 while (count > 0) {
393 len = min_t(unsigned int, count, sizeof(buffer));
394
395 /* Read some data from the byte channel. This function will
396 * never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.
397 */
398 ev_byte_channel_receive(bc->handle, &len, buffer);
399
400 /* 'len' is now the amount of data that's been received. 'len'
401 * can't be zero, and most likely it's equal to one.
402 */
403
404 /* Pass the received data to the tty layer. */
Jiri Slaby05c7cd32013-01-03 15:53:04 +0100405 ret = tty_insert_flip_string(&bc->port, buffer, len);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500406
407 /* 'ret' is the number of bytes that the TTY layer accepted.
408 * If it's not equal to 'len', then it means the buffer is
409 * full, which should never happen. If it does happen, we can
410 * exit gracefully, but we drop the last 'len - ret' characters
411 * that we read from the byte channel.
412 */
413 if (ret != len)
414 break;
415
416 count -= len;
417 }
418
419 /* Tell the tty layer that we're done. */
Jiri Slaby2e124b42013-01-03 15:53:06 +0100420 tty_flip_buffer_push(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500421
422 return IRQ_HANDLED;
423}
424
425/*
426 * dequeue the transmit buffer to the hypervisor
427 *
428 * This function, which can be called in interrupt context, dequeues as much
429 * data as possible from the transmit buffer to the byte channel.
430 */
431static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)
432{
433 unsigned int count;
434 unsigned int len, ret;
435 unsigned long flags;
436
437 do {
438 spin_lock_irqsave(&bc->lock, flags);
439 len = min_t(unsigned int,
440 CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
441 EV_BYTE_CHANNEL_MAX_BYTES);
442
443 ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);
444
445 /* 'len' is valid only if the return code is 0 or EV_EAGAIN */
446 if (!ret || (ret == EV_EAGAIN))
447 bc->tail = (bc->tail + len) & (BUF_SIZE - 1);
448
449 count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);
450 spin_unlock_irqrestore(&bc->lock, flags);
451 } while (count && !ret);
452
453 spin_lock_irqsave(&bc->lock, flags);
454 if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))
455 /*
456 * If we haven't emptied the buffer, then enable the TX IRQ.
457 * We'll get an interrupt when there's more room in the
458 * hypervisor's output buffer.
459 */
460 enable_tx_interrupt(bc);
461 else
462 disable_tx_interrupt(bc);
463 spin_unlock_irqrestore(&bc->lock, flags);
464}
465
466/*
467 * byte channel transmit interupt handler
468 *
469 * This ISR is called whenever space becomes available for transmitting
470 * characters on a byte channel.
471 */
472static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
473{
474 struct ehv_bc_data *bc = data;
475 struct tty_struct *ttys = tty_port_tty_get(&bc->port);
476
477 ehv_bc_tx_dequeue(bc);
478 if (ttys) {
479 tty_wakeup(ttys);
480 tty_kref_put(ttys);
481 }
482
483 return IRQ_HANDLED;
484}
485
486/*
487 * This function is called when the tty layer has data for us send. We store
488 * the data first in a circular buffer, and then dequeue as much of that data
489 * as possible.
490 *
491 * We don't need to worry about whether there is enough room in the buffer for
492 * all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty
493 * layer how much data it can safely send to us. We guarantee that
494 * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
495 * too much data.
496 */
497static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s,
498 int count)
499{
500 struct ehv_bc_data *bc = ttys->driver_data;
501 unsigned long flags;
502 unsigned int len;
503 unsigned int written = 0;
504
505 while (1) {
506 spin_lock_irqsave(&bc->lock, flags);
507 len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
508 if (count < len)
509 len = count;
510 if (len) {
511 memcpy(bc->buf + bc->head, s, len);
512 bc->head = (bc->head + len) & (BUF_SIZE - 1);
513 }
514 spin_unlock_irqrestore(&bc->lock, flags);
515 if (!len)
516 break;
517
518 s += len;
519 count -= len;
520 written += len;
521 }
522
523 ehv_bc_tx_dequeue(bc);
524
525 return written;
526}
527
528/*
529 * This function can be called multiple times for a given tty_struct, which is
530 * why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.
531 *
532 * The tty layer will still call this function even if the device was not
533 * registered (i.e. tty_register_device() was not called). This happens
534 * because tty_register_device() is optional and some legacy drivers don't
535 * use it. So we need to check for that.
536 */
537static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)
538{
539 struct ehv_bc_data *bc = &bcs[ttys->index];
540
541 if (!bc->dev)
542 return -ENODEV;
543
544 return tty_port_open(&bc->port, ttys, filp);
545}
546
547/*
548 * Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will
549 * still call this function to close the tty device. So we can't assume that
550 * the tty port has been initialized.
551 */
552static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)
553{
554 struct ehv_bc_data *bc = &bcs[ttys->index];
555
556 if (bc->dev)
557 tty_port_close(&bc->port, ttys, filp);
558}
559
560/*
561 * Return the amount of space in the output buffer
562 *
563 * This is actually a contract between the driver and the tty layer outlining
564 * how much write room the driver can guarantee will be sent OR BUFFERED. This
565 * driver MUST honor the return value.
566 */
567static int ehv_bc_tty_write_room(struct tty_struct *ttys)
568{
569 struct ehv_bc_data *bc = ttys->driver_data;
570 unsigned long flags;
571 int count;
572
573 spin_lock_irqsave(&bc->lock, flags);
574 count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
575 spin_unlock_irqrestore(&bc->lock, flags);
576
577 return count;
578}
579
580/*
581 * Stop sending data to the tty layer
582 *
583 * This function is called when the tty layer's input buffers are getting full,
584 * so the driver should stop sending it data. The easiest way to do this is to
585 * disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being
586 * called.
587 *
588 * The hypervisor will continue to queue up any incoming data. If there is any
589 * data in the queue when the RX interrupt is enabled, we'll immediately get an
590 * RX interrupt.
591 */
592static void ehv_bc_tty_throttle(struct tty_struct *ttys)
593{
594 struct ehv_bc_data *bc = ttys->driver_data;
595
596 disable_irq(bc->rx_irq);
597}
598
599/*
600 * Resume sending data to the tty layer
601 *
602 * This function is called after previously calling ehv_bc_tty_throttle(). The
603 * tty layer's input buffers now have more room, so the driver can resume
604 * sending it data.
605 */
606static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)
607{
608 struct ehv_bc_data *bc = ttys->driver_data;
609
610 /* If there is any data in the queue when the RX interrupt is enabled,
611 * we'll immediately get an RX interrupt.
612 */
613 enable_irq(bc->rx_irq);
614}
615
616static void ehv_bc_tty_hangup(struct tty_struct *ttys)
617{
618 struct ehv_bc_data *bc = ttys->driver_data;
619
620 ehv_bc_tx_dequeue(bc);
621 tty_port_hangup(&bc->port);
622}
623
624/*
625 * TTY driver operations
626 *
627 * If we could ask the hypervisor how much data is still in the TX buffer, or
628 * at least how big the TX buffers are, then we could implement the
629 * .wait_until_sent and .chars_in_buffer functions.
630 */
631static const struct tty_operations ehv_bc_ops = {
632 .open = ehv_bc_tty_open,
633 .close = ehv_bc_tty_close,
634 .write = ehv_bc_tty_write,
635 .write_room = ehv_bc_tty_write_room,
636 .throttle = ehv_bc_tty_throttle,
637 .unthrottle = ehv_bc_tty_unthrottle,
638 .hangup = ehv_bc_tty_hangup,
639};
640
641/*
642 * initialize the TTY port
643 *
644 * This function will only be called once, no matter how many times
645 * ehv_bc_tty_open() is called. That's why we register the ISR here, and also
646 * why we initialize tty_struct-related variables here.
647 */
648static int ehv_bc_tty_port_activate(struct tty_port *port,
649 struct tty_struct *ttys)
650{
651 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
652 int ret;
653
654 ttys->driver_data = bc;
655
656 ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);
657 if (ret < 0) {
658 dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",
659 bc->rx_irq, ret);
660 return ret;
661 }
662
663 /* request_irq also enables the IRQ */
664 bc->tx_irq_enabled = 1;
665
666 ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);
667 if (ret < 0) {
668 dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",
669 bc->tx_irq, ret);
670 free_irq(bc->rx_irq, bc);
671 return ret;
672 }
673
674 /* The TX IRQ is enabled only when we can't write all the data to the
675 * byte channel at once, so by default it's disabled.
676 */
677 disable_tx_interrupt(bc);
678
679 return 0;
680}
681
682static void ehv_bc_tty_port_shutdown(struct tty_port *port)
683{
684 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
685
686 free_irq(bc->tx_irq, bc);
687 free_irq(bc->rx_irq, bc);
688}
689
690static const struct tty_port_operations ehv_bc_tty_port_ops = {
691 .activate = ehv_bc_tty_port_activate,
692 .shutdown = ehv_bc_tty_port_shutdown,
693};
694
Bill Pemberton9671f092012-11-19 13:21:50 -0500695static int ehv_bc_tty_probe(struct platform_device *pdev)
Timur Tabidcd83aa2011-07-08 19:06:12 -0500696{
697 struct device_node *np = pdev->dev.of_node;
698 struct ehv_bc_data *bc;
699 const uint32_t *iprop;
700 unsigned int handle;
701 int ret;
702 static unsigned int index = 1;
703 unsigned int i;
704
705 iprop = of_get_property(np, "hv-handle", NULL);
706 if (!iprop) {
707 dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n",
708 np->name);
709 return -ENODEV;
710 }
711
712 /* We already told the console layer that the index for the console
713 * device is zero, so we need to make sure that we use that index when
714 * we probe the console byte channel node.
715 */
716 handle = be32_to_cpu(*iprop);
717 i = (handle == stdout_bc) ? 0 : index++;
718 bc = &bcs[i];
719
720 bc->handle = handle;
721 bc->head = 0;
722 bc->tail = 0;
723 spin_lock_init(&bc->lock);
724
725 bc->rx_irq = irq_of_parse_and_map(np, 0);
726 bc->tx_irq = irq_of_parse_and_map(np, 1);
727 if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) {
728 dev_err(&pdev->dev, "no 'interrupts' property in %s node\n",
729 np->name);
730 ret = -ENODEV;
731 goto error;
732 }
733
Jiri Slaby734cc172012-08-07 21:47:47 +0200734 tty_port_init(&bc->port);
735 bc->port.ops = &ehv_bc_tty_port_ops;
736
737 bc->dev = tty_port_register_device(&bc->port, ehv_bc_driver, i,
738 &pdev->dev);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500739 if (IS_ERR(bc->dev)) {
740 ret = PTR_ERR(bc->dev);
741 dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);
742 goto error;
743 }
744
Timur Tabidcd83aa2011-07-08 19:06:12 -0500745 dev_set_drvdata(&pdev->dev, bc);
746
747 dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",
748 ehv_bc_driver->name, i, bc->handle);
749
750 return 0;
751
752error:
Jiri Slaby191c5f12012-11-15 09:49:56 +0100753 tty_port_destroy(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500754 irq_dispose_mapping(bc->tx_irq);
755 irq_dispose_mapping(bc->rx_irq);
756
757 memset(bc, 0, sizeof(struct ehv_bc_data));
758 return ret;
759}
760
761static int ehv_bc_tty_remove(struct platform_device *pdev)
762{
763 struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev);
764
765 tty_unregister_device(ehv_bc_driver, bc - bcs);
766
Jiri Slaby191c5f12012-11-15 09:49:56 +0100767 tty_port_destroy(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500768 irq_dispose_mapping(bc->tx_irq);
769 irq_dispose_mapping(bc->rx_irq);
770
771 return 0;
772}
773
774static const struct of_device_id ehv_bc_tty_of_ids[] = {
775 { .compatible = "epapr,hv-byte-channel" },
776 {}
777};
778
779static struct platform_driver ehv_bc_tty_driver = {
780 .driver = {
781 .owner = THIS_MODULE,
782 .name = "ehv-bc",
783 .of_match_table = ehv_bc_tty_of_ids,
784 },
785 .probe = ehv_bc_tty_probe,
786 .remove = ehv_bc_tty_remove,
787};
788
789/**
790 * ehv_bc_init - ePAPR hypervisor byte channel driver initialization
791 *
792 * This function is called when this module is loaded.
793 */
794static int __init ehv_bc_init(void)
795{
796 struct device_node *np;
797 unsigned int count = 0; /* Number of elements in bcs[] */
798 int ret;
799
800 pr_info("ePAPR hypervisor byte channel driver\n");
801
802 /* Count the number of byte channels */
803 for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")
804 count++;
805
806 if (!count)
807 return -ENODEV;
808
809 /* The array index of an element in bcs[] is the same as the tty index
810 * for that element. If you know the address of an element in the
811 * array, then you can use pointer math (e.g. "bc - bcs") to get its
812 * tty index.
813 */
814 bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL);
815 if (!bcs)
816 return -ENOMEM;
817
818 ehv_bc_driver = alloc_tty_driver(count);
819 if (!ehv_bc_driver) {
820 ret = -ENOMEM;
821 goto error;
822 }
823
Timur Tabidcd83aa2011-07-08 19:06:12 -0500824 ehv_bc_driver->driver_name = "ehv-bc";
825 ehv_bc_driver->name = ehv_bc_console.name;
826 ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE;
827 ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE;
828 ehv_bc_driver->init_termios = tty_std_termios;
829 ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
830 tty_set_operations(ehv_bc_driver, &ehv_bc_ops);
831
832 ret = tty_register_driver(ehv_bc_driver);
833 if (ret) {
834 pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);
835 goto error;
836 }
837
838 ret = platform_driver_register(&ehv_bc_tty_driver);
839 if (ret) {
840 pr_err("ehv-bc: could not register platform driver (ret=%i)\n",
841 ret);
842 goto error;
843 }
844
845 return 0;
846
847error:
848 if (ehv_bc_driver) {
849 tty_unregister_driver(ehv_bc_driver);
850 put_tty_driver(ehv_bc_driver);
851 }
852
853 kfree(bcs);
854
855 return ret;
856}
857
858
859/**
860 * ehv_bc_exit - ePAPR hypervisor byte channel driver termination
861 *
862 * This function is called when this driver is unloaded.
863 */
864static void __exit ehv_bc_exit(void)
865{
866 tty_unregister_driver(ehv_bc_driver);
867 put_tty_driver(ehv_bc_driver);
868 kfree(bcs);
869}
870
871module_init(ehv_bc_init);
872module_exit(ehv_bc_exit);
873
874MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
875MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
876MODULE_LICENSE("GPL v2");