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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>
Rob Herring5af50732013-09-17 14:28:33 -050035#include <linux/of_irq.h>
Timur Tabidcd83aa2011-07-08 19:06:12 -050036#include <linux/platform_device.h>
37#include <linux/cdev.h>
38#include <linux/console.h>
39#include <linux/tty.h>
40#include <linux/tty_flip.h>
41#include <linux/circ_buf.h>
42#include <asm/udbg.h>
43
44/* The size of the transmit circular buffer. This must be a power of two. */
45#define BUF_SIZE 2048
46
47/* Per-byte channel private data */
48struct ehv_bc_data {
49 struct device *dev;
50 struct tty_port port;
51 uint32_t handle;
52 unsigned int rx_irq;
53 unsigned int tx_irq;
54
55 spinlock_t lock; /* lock for transmit buffer */
56 unsigned char buf[BUF_SIZE]; /* transmit circular buffer */
57 unsigned int head; /* circular buffer head */
58 unsigned int tail; /* circular buffer tail */
59
60 int tx_irq_enabled; /* true == TX interrupt is enabled */
61};
62
63/* Array of byte channel objects */
64static struct ehv_bc_data *bcs;
65
66/* Byte channel handle for stdout (and stdin), taken from device tree */
67static unsigned int stdout_bc;
68
69/* Virtual IRQ for the byte channel handle for stdin, taken from device tree */
70static unsigned int stdout_irq;
71
72/**************************** SUPPORT FUNCTIONS ****************************/
73
74/*
75 * Enable the transmit interrupt
76 *
77 * Unlike a serial device, byte channels have no mechanism for disabling their
78 * own receive or transmit interrupts. To emulate that feature, we toggle
79 * the IRQ in the kernel.
80 *
81 * We cannot just blindly call enable_irq() or disable_irq(), because these
82 * calls are reference counted. This means that we cannot call enable_irq()
83 * if interrupts are already enabled. This can happen in two situations:
84 *
85 * 1. The tty layer makes two back-to-back calls to ehv_bc_tty_write()
86 * 2. A transmit interrupt occurs while executing ehv_bc_tx_dequeue()
87 *
88 * To work around this, we keep a flag to tell us if the IRQ is enabled or not.
89 */
90static void enable_tx_interrupt(struct ehv_bc_data *bc)
91{
92 if (!bc->tx_irq_enabled) {
93 enable_irq(bc->tx_irq);
94 bc->tx_irq_enabled = 1;
95 }
96}
97
98static void disable_tx_interrupt(struct ehv_bc_data *bc)
99{
100 if (bc->tx_irq_enabled) {
101 disable_irq_nosync(bc->tx_irq);
102 bc->tx_irq_enabled = 0;
103 }
104}
105
106/*
107 * find the byte channel handle to use for the console
108 *
109 * The byte channel to be used for the console is specified via a "stdout"
110 * property in the /chosen node.
Timur Tabidcd83aa2011-07-08 19:06:12 -0500111 */
112static int find_console_handle(void)
113{
Grant Likelya752ee52014-03-28 08:12:18 -0700114 struct device_node *np = of_stdout;
Timur Tabidcd83aa2011-07-08 19:06:12 -0500115 const char *sprop = NULL;
116 const uint32_t *iprop;
117
Timur Tabidcd83aa2011-07-08 19:06:12 -0500118 /* We don't care what the aliased node is actually called. We only
119 * care if it's compatible with "epapr,hv-byte-channel", because that
Grant Likelya752ee52014-03-28 08:12:18 -0700120 * indicates that it's a byte channel node.
Timur Tabidcd83aa2011-07-08 19:06:12 -0500121 */
Grant Likelya752ee52014-03-28 08:12:18 -0700122 if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))
Timur Tabidcd83aa2011-07-08 19:06:12 -0500123 return 0;
Timur Tabidcd83aa2011-07-08 19:06:12 -0500124
125 stdout_irq = irq_of_parse_and_map(np, 0);
126 if (stdout_irq == NO_IRQ) {
Grant Likelya752ee52014-03-28 08:12:18 -0700127 pr_err("ehv-bc: no 'interrupts' property in %s node\n", np->full_name);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500128 return 0;
129 }
130
131 /*
132 * The 'hv-handle' property contains the handle for this byte channel.
133 */
134 iprop = of_get_property(np, "hv-handle", NULL);
135 if (!iprop) {
136 pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
137 np->name);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500138 return 0;
139 }
140 stdout_bc = be32_to_cpu(*iprop);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500141 return 1;
142}
143
144/*************************** EARLY CONSOLE DRIVER ***************************/
145
146#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
147
148/*
149 * send a byte to a byte channel, wait if necessary
150 *
151 * This function sends a byte to a byte channel, and it waits and
152 * retries if the byte channel is full. It returns if the character
153 * has been sent, or if some error has occurred.
154 *
155 */
156static void byte_channel_spin_send(const char data)
157{
158 int ret, count;
159
160 do {
161 count = 1;
162 ret = ev_byte_channel_send(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
163 &count, &data);
164 } while (ret == EV_EAGAIN);
165}
166
167/*
168 * The udbg subsystem calls this function to display a single character.
169 * We convert CR to a CR/LF.
170 */
171static void ehv_bc_udbg_putc(char c)
172{
173 if (c == '\n')
174 byte_channel_spin_send('\r');
175
176 byte_channel_spin_send(c);
177}
178
179/*
180 * early console initialization
181 *
182 * PowerPC kernels support an early printk console, also known as udbg.
183 * This function must be called via the ppc_md.init_early function pointer.
184 * At this point, the device tree has been unflattened, so we can obtain the
185 * byte channel handle for stdout.
186 *
187 * We only support displaying of characters (putc). We do not support
188 * keyboard input.
189 */
190void __init udbg_init_ehv_bc(void)
191{
192 unsigned int rx_count, tx_count;
193 unsigned int ret;
194
Timur Tabidcd83aa2011-07-08 19:06:12 -0500195 /* Verify the byte channel handle */
196 ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
197 &rx_count, &tx_count);
198 if (ret)
199 return;
200
201 udbg_putc = ehv_bc_udbg_putc;
202 register_early_udbg_console();
203
204 udbg_printf("ehv-bc: early console using byte channel handle %u\n",
205 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
206}
207
208#endif
209
210/****************************** CONSOLE DRIVER ******************************/
211
212static struct tty_driver *ehv_bc_driver;
213
214/*
215 * Byte channel console sending worker function.
216 *
217 * For consoles, if the output buffer is full, we should just spin until it
218 * clears.
219 */
220static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,
221 unsigned int count)
222{
223 unsigned int len;
224 int ret = 0;
225
226 while (count) {
227 len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);
228 do {
229 ret = ev_byte_channel_send(handle, &len, s);
230 } while (ret == EV_EAGAIN);
231 count -= len;
232 s += len;
233 }
234
235 return ret;
236}
237
238/*
239 * write a string to the console
240 *
241 * This function gets called to write a string from the kernel, typically from
242 * a printk(). This function spins until all data is written.
243 *
244 * We copy the data to a temporary buffer because we need to insert a \r in
245 * front of every \n. It's more efficient to copy the data to the buffer than
246 * it is to make multiple hcalls for each character or each newline.
247 */
248static void ehv_bc_console_write(struct console *co, const char *s,
249 unsigned int count)
250{
Timur Tabidcd83aa2011-07-08 19:06:12 -0500251 char s2[EV_BYTE_CHANNEL_MAX_BYTES];
252 unsigned int i, j = 0;
253 char c;
254
255 for (i = 0; i < count; i++) {
256 c = *s++;
257
258 if (c == '\n')
259 s2[j++] = '\r';
260
261 s2[j++] = c;
262 if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {
Timur Tabifd01a7a2011-09-22 20:33:13 -0500263 if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j))
Timur Tabidcd83aa2011-07-08 19:06:12 -0500264 return;
265 j = 0;
266 }
267 }
268
269 if (j)
Timur Tabifd01a7a2011-09-22 20:33:13 -0500270 ehv_bc_console_byte_channel_send(stdout_bc, s2, j);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500271}
272
273/*
274 * When /dev/console is opened, the kernel iterates the console list looking
275 * for one with ->device and then calls that method. On success, it expects
276 * the passed-in int* to contain the minor number to use.
277 */
278static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)
279{
280 *index = co->index;
281
282 return ehv_bc_driver;
283}
284
285static struct console ehv_bc_console = {
286 .name = "ttyEHV",
287 .write = ehv_bc_console_write,
288 .device = ehv_bc_console_device,
289 .flags = CON_PRINTBUFFER | CON_ENABLED,
290};
291
292/*
293 * Console initialization
294 *
295 * This is the first function that is called after the device tree is
296 * available, so here is where we determine the byte channel handle and IRQ for
297 * stdout/stdin, even though that information is used by the tty and character
298 * drivers.
299 */
300static int __init ehv_bc_console_init(void)
301{
302 if (!find_console_handle()) {
303 pr_debug("ehv-bc: stdout is not a byte channel\n");
304 return -ENODEV;
305 }
306
307#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
308 /* Print a friendly warning if the user chose the wrong byte channel
309 * handle for udbg.
310 */
311 if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)
312 pr_warning("ehv-bc: udbg handle %u is not the stdout handle\n",
313 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
314#endif
315
Timur Tabidcd83aa2011-07-08 19:06:12 -0500316 /* add_preferred_console() must be called before register_console(),
317 otherwise it won't work. However, we don't want to enumerate all the
318 byte channels here, either, since we only care about one. */
319
320 add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);
321 register_console(&ehv_bc_console);
322
323 pr_info("ehv-bc: registered console driver for byte channel %u\n",
324 stdout_bc);
325
326 return 0;
327}
328console_initcall(ehv_bc_console_init);
329
330/******************************** TTY DRIVER ********************************/
331
332/*
333 * byte channel receive interupt handler
334 *
335 * This ISR is called whenever data is available on a byte channel.
336 */
337static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
338{
339 struct ehv_bc_data *bc = data;
Timur Tabidcd83aa2011-07-08 19:06:12 -0500340 unsigned int rx_count, tx_count, len;
341 int count;
342 char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
343 int ret;
344
Timur Tabidcd83aa2011-07-08 19:06:12 -0500345 /* Find out how much data needs to be read, and then ask the TTY layer
346 * if it can handle that much. We want to ensure that every byte we
347 * read from the byte channel will be accepted by the TTY layer.
348 */
349 ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);
Jiri Slaby227434f2013-01-03 15:53:01 +0100350 count = tty_buffer_request_room(&bc->port, rx_count);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500351
352 /* 'count' is the maximum amount of data the TTY layer can accept at
353 * this time. However, during testing, I was never able to get 'count'
354 * to be less than 'rx_count'. I'm not sure whether I'm calling it
355 * correctly.
356 */
357
358 while (count > 0) {
359 len = min_t(unsigned int, count, sizeof(buffer));
360
361 /* Read some data from the byte channel. This function will
362 * never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.
363 */
364 ev_byte_channel_receive(bc->handle, &len, buffer);
365
366 /* 'len' is now the amount of data that's been received. 'len'
367 * can't be zero, and most likely it's equal to one.
368 */
369
370 /* Pass the received data to the tty layer. */
Jiri Slaby05c7cd32013-01-03 15:53:04 +0100371 ret = tty_insert_flip_string(&bc->port, buffer, len);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500372
373 /* 'ret' is the number of bytes that the TTY layer accepted.
374 * If it's not equal to 'len', then it means the buffer is
375 * full, which should never happen. If it does happen, we can
376 * exit gracefully, but we drop the last 'len - ret' characters
377 * that we read from the byte channel.
378 */
379 if (ret != len)
380 break;
381
382 count -= len;
383 }
384
385 /* Tell the tty layer that we're done. */
Jiri Slaby2e124b42013-01-03 15:53:06 +0100386 tty_flip_buffer_push(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500387
388 return IRQ_HANDLED;
389}
390
391/*
392 * dequeue the transmit buffer to the hypervisor
393 *
394 * This function, which can be called in interrupt context, dequeues as much
395 * data as possible from the transmit buffer to the byte channel.
396 */
397static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)
398{
399 unsigned int count;
400 unsigned int len, ret;
401 unsigned long flags;
402
403 do {
404 spin_lock_irqsave(&bc->lock, flags);
405 len = min_t(unsigned int,
406 CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
407 EV_BYTE_CHANNEL_MAX_BYTES);
408
409 ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);
410
411 /* 'len' is valid only if the return code is 0 or EV_EAGAIN */
412 if (!ret || (ret == EV_EAGAIN))
413 bc->tail = (bc->tail + len) & (BUF_SIZE - 1);
414
415 count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);
416 spin_unlock_irqrestore(&bc->lock, flags);
417 } while (count && !ret);
418
419 spin_lock_irqsave(&bc->lock, flags);
420 if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))
421 /*
422 * If we haven't emptied the buffer, then enable the TX IRQ.
423 * We'll get an interrupt when there's more room in the
424 * hypervisor's output buffer.
425 */
426 enable_tx_interrupt(bc);
427 else
428 disable_tx_interrupt(bc);
429 spin_unlock_irqrestore(&bc->lock, flags);
430}
431
432/*
433 * byte channel transmit interupt handler
434 *
435 * This ISR is called whenever space becomes available for transmitting
436 * characters on a byte channel.
437 */
438static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
439{
440 struct ehv_bc_data *bc = data;
Timur Tabidcd83aa2011-07-08 19:06:12 -0500441
442 ehv_bc_tx_dequeue(bc);
Jiri Slaby6aad04f2013-03-07 13:12:29 +0100443 tty_port_tty_wakeup(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500444
445 return IRQ_HANDLED;
446}
447
448/*
449 * This function is called when the tty layer has data for us send. We store
450 * the data first in a circular buffer, and then dequeue as much of that data
451 * as possible.
452 *
453 * We don't need to worry about whether there is enough room in the buffer for
454 * all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty
455 * layer how much data it can safely send to us. We guarantee that
456 * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
457 * too much data.
458 */
459static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s,
460 int count)
461{
462 struct ehv_bc_data *bc = ttys->driver_data;
463 unsigned long flags;
464 unsigned int len;
465 unsigned int written = 0;
466
467 while (1) {
468 spin_lock_irqsave(&bc->lock, flags);
469 len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
470 if (count < len)
471 len = count;
472 if (len) {
473 memcpy(bc->buf + bc->head, s, len);
474 bc->head = (bc->head + len) & (BUF_SIZE - 1);
475 }
476 spin_unlock_irqrestore(&bc->lock, flags);
477 if (!len)
478 break;
479
480 s += len;
481 count -= len;
482 written += len;
483 }
484
485 ehv_bc_tx_dequeue(bc);
486
487 return written;
488}
489
490/*
491 * This function can be called multiple times for a given tty_struct, which is
492 * why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.
493 *
494 * The tty layer will still call this function even if the device was not
495 * registered (i.e. tty_register_device() was not called). This happens
496 * because tty_register_device() is optional and some legacy drivers don't
497 * use it. So we need to check for that.
498 */
499static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)
500{
501 struct ehv_bc_data *bc = &bcs[ttys->index];
502
503 if (!bc->dev)
504 return -ENODEV;
505
506 return tty_port_open(&bc->port, ttys, filp);
507}
508
509/*
510 * Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will
511 * still call this function to close the tty device. So we can't assume that
512 * the tty port has been initialized.
513 */
514static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)
515{
516 struct ehv_bc_data *bc = &bcs[ttys->index];
517
518 if (bc->dev)
519 tty_port_close(&bc->port, ttys, filp);
520}
521
522/*
523 * Return the amount of space in the output buffer
524 *
525 * This is actually a contract between the driver and the tty layer outlining
526 * how much write room the driver can guarantee will be sent OR BUFFERED. This
527 * driver MUST honor the return value.
528 */
529static int ehv_bc_tty_write_room(struct tty_struct *ttys)
530{
531 struct ehv_bc_data *bc = ttys->driver_data;
532 unsigned long flags;
533 int count;
534
535 spin_lock_irqsave(&bc->lock, flags);
536 count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
537 spin_unlock_irqrestore(&bc->lock, flags);
538
539 return count;
540}
541
542/*
543 * Stop sending data to the tty layer
544 *
545 * This function is called when the tty layer's input buffers are getting full,
546 * so the driver should stop sending it data. The easiest way to do this is to
547 * disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being
548 * called.
549 *
550 * The hypervisor will continue to queue up any incoming data. If there is any
551 * data in the queue when the RX interrupt is enabled, we'll immediately get an
552 * RX interrupt.
553 */
554static void ehv_bc_tty_throttle(struct tty_struct *ttys)
555{
556 struct ehv_bc_data *bc = ttys->driver_data;
557
558 disable_irq(bc->rx_irq);
559}
560
561/*
562 * Resume sending data to the tty layer
563 *
564 * This function is called after previously calling ehv_bc_tty_throttle(). The
565 * tty layer's input buffers now have more room, so the driver can resume
566 * sending it data.
567 */
568static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)
569{
570 struct ehv_bc_data *bc = ttys->driver_data;
571
572 /* If there is any data in the queue when the RX interrupt is enabled,
573 * we'll immediately get an RX interrupt.
574 */
575 enable_irq(bc->rx_irq);
576}
577
578static void ehv_bc_tty_hangup(struct tty_struct *ttys)
579{
580 struct ehv_bc_data *bc = ttys->driver_data;
581
582 ehv_bc_tx_dequeue(bc);
583 tty_port_hangup(&bc->port);
584}
585
586/*
587 * TTY driver operations
588 *
589 * If we could ask the hypervisor how much data is still in the TX buffer, or
590 * at least how big the TX buffers are, then we could implement the
591 * .wait_until_sent and .chars_in_buffer functions.
592 */
593static const struct tty_operations ehv_bc_ops = {
594 .open = ehv_bc_tty_open,
595 .close = ehv_bc_tty_close,
596 .write = ehv_bc_tty_write,
597 .write_room = ehv_bc_tty_write_room,
598 .throttle = ehv_bc_tty_throttle,
599 .unthrottle = ehv_bc_tty_unthrottle,
600 .hangup = ehv_bc_tty_hangup,
601};
602
603/*
604 * initialize the TTY port
605 *
606 * This function will only be called once, no matter how many times
607 * ehv_bc_tty_open() is called. That's why we register the ISR here, and also
608 * why we initialize tty_struct-related variables here.
609 */
610static int ehv_bc_tty_port_activate(struct tty_port *port,
611 struct tty_struct *ttys)
612{
613 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
614 int ret;
615
616 ttys->driver_data = bc;
617
618 ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);
619 if (ret < 0) {
620 dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",
621 bc->rx_irq, ret);
622 return ret;
623 }
624
625 /* request_irq also enables the IRQ */
626 bc->tx_irq_enabled = 1;
627
628 ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);
629 if (ret < 0) {
630 dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",
631 bc->tx_irq, ret);
632 free_irq(bc->rx_irq, bc);
633 return ret;
634 }
635
636 /* The TX IRQ is enabled only when we can't write all the data to the
637 * byte channel at once, so by default it's disabled.
638 */
639 disable_tx_interrupt(bc);
640
641 return 0;
642}
643
644static void ehv_bc_tty_port_shutdown(struct tty_port *port)
645{
646 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
647
648 free_irq(bc->tx_irq, bc);
649 free_irq(bc->rx_irq, bc);
650}
651
652static const struct tty_port_operations ehv_bc_tty_port_ops = {
653 .activate = ehv_bc_tty_port_activate,
654 .shutdown = ehv_bc_tty_port_shutdown,
655};
656
Bill Pemberton9671f092012-11-19 13:21:50 -0500657static int ehv_bc_tty_probe(struct platform_device *pdev)
Timur Tabidcd83aa2011-07-08 19:06:12 -0500658{
659 struct device_node *np = pdev->dev.of_node;
660 struct ehv_bc_data *bc;
661 const uint32_t *iprop;
662 unsigned int handle;
663 int ret;
664 static unsigned int index = 1;
665 unsigned int i;
666
667 iprop = of_get_property(np, "hv-handle", NULL);
668 if (!iprop) {
669 dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n",
670 np->name);
671 return -ENODEV;
672 }
673
674 /* We already told the console layer that the index for the console
675 * device is zero, so we need to make sure that we use that index when
676 * we probe the console byte channel node.
677 */
678 handle = be32_to_cpu(*iprop);
679 i = (handle == stdout_bc) ? 0 : index++;
680 bc = &bcs[i];
681
682 bc->handle = handle;
683 bc->head = 0;
684 bc->tail = 0;
685 spin_lock_init(&bc->lock);
686
687 bc->rx_irq = irq_of_parse_and_map(np, 0);
688 bc->tx_irq = irq_of_parse_and_map(np, 1);
689 if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) {
690 dev_err(&pdev->dev, "no 'interrupts' property in %s node\n",
691 np->name);
692 ret = -ENODEV;
693 goto error;
694 }
695
Jiri Slaby734cc172012-08-07 21:47:47 +0200696 tty_port_init(&bc->port);
697 bc->port.ops = &ehv_bc_tty_port_ops;
698
699 bc->dev = tty_port_register_device(&bc->port, ehv_bc_driver, i,
700 &pdev->dev);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500701 if (IS_ERR(bc->dev)) {
702 ret = PTR_ERR(bc->dev);
703 dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);
704 goto error;
705 }
706
Timur Tabidcd83aa2011-07-08 19:06:12 -0500707 dev_set_drvdata(&pdev->dev, bc);
708
709 dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",
710 ehv_bc_driver->name, i, bc->handle);
711
712 return 0;
713
714error:
Jiri Slaby191c5f12012-11-15 09:49:56 +0100715 tty_port_destroy(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500716 irq_dispose_mapping(bc->tx_irq);
717 irq_dispose_mapping(bc->rx_irq);
718
719 memset(bc, 0, sizeof(struct ehv_bc_data));
720 return ret;
721}
722
723static int ehv_bc_tty_remove(struct platform_device *pdev)
724{
725 struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev);
726
727 tty_unregister_device(ehv_bc_driver, bc - bcs);
728
Jiri Slaby191c5f12012-11-15 09:49:56 +0100729 tty_port_destroy(&bc->port);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500730 irq_dispose_mapping(bc->tx_irq);
731 irq_dispose_mapping(bc->rx_irq);
732
733 return 0;
734}
735
736static const struct of_device_id ehv_bc_tty_of_ids[] = {
737 { .compatible = "epapr,hv-byte-channel" },
738 {}
739};
740
741static struct platform_driver ehv_bc_tty_driver = {
742 .driver = {
743 .owner = THIS_MODULE,
744 .name = "ehv-bc",
745 .of_match_table = ehv_bc_tty_of_ids,
746 },
747 .probe = ehv_bc_tty_probe,
748 .remove = ehv_bc_tty_remove,
749};
750
751/**
752 * ehv_bc_init - ePAPR hypervisor byte channel driver initialization
753 *
754 * This function is called when this module is loaded.
755 */
756static int __init ehv_bc_init(void)
757{
758 struct device_node *np;
759 unsigned int count = 0; /* Number of elements in bcs[] */
760 int ret;
761
762 pr_info("ePAPR hypervisor byte channel driver\n");
763
764 /* Count the number of byte channels */
765 for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")
766 count++;
767
768 if (!count)
769 return -ENODEV;
770
771 /* The array index of an element in bcs[] is the same as the tty index
772 * for that element. If you know the address of an element in the
773 * array, then you can use pointer math (e.g. "bc - bcs") to get its
774 * tty index.
775 */
776 bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL);
777 if (!bcs)
778 return -ENOMEM;
779
780 ehv_bc_driver = alloc_tty_driver(count);
781 if (!ehv_bc_driver) {
782 ret = -ENOMEM;
783 goto error;
784 }
785
Timur Tabidcd83aa2011-07-08 19:06:12 -0500786 ehv_bc_driver->driver_name = "ehv-bc";
787 ehv_bc_driver->name = ehv_bc_console.name;
788 ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE;
789 ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE;
790 ehv_bc_driver->init_termios = tty_std_termios;
791 ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
792 tty_set_operations(ehv_bc_driver, &ehv_bc_ops);
793
794 ret = tty_register_driver(ehv_bc_driver);
795 if (ret) {
796 pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);
797 goto error;
798 }
799
800 ret = platform_driver_register(&ehv_bc_tty_driver);
801 if (ret) {
802 pr_err("ehv-bc: could not register platform driver (ret=%i)\n",
803 ret);
804 goto error;
805 }
806
807 return 0;
808
809error:
810 if (ehv_bc_driver) {
811 tty_unregister_driver(ehv_bc_driver);
812 put_tty_driver(ehv_bc_driver);
813 }
814
815 kfree(bcs);
816
817 return ret;
818}
819
820
821/**
822 * ehv_bc_exit - ePAPR hypervisor byte channel driver termination
823 *
824 * This function is called when this driver is unloaded.
825 */
826static void __exit ehv_bc_exit(void)
827{
Wei Yongjundf957d22013-04-27 18:14:56 +0800828 platform_driver_unregister(&ehv_bc_tty_driver);
Timur Tabidcd83aa2011-07-08 19:06:12 -0500829 tty_unregister_driver(ehv_bc_driver);
830 put_tty_driver(ehv_bc_driver);
831 kfree(bcs);
832}
833
834module_init(ehv_bc_init);
835module_exit(ehv_bc_exit);
836
837MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
838MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
839MODULE_LICENSE("GPL v2");