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authorTimur Tabi <timur@freescale.com>2011-07-08 20:06:12 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-08-23 13:32:56 -0400
commitdcd83aaff1c8cbd5b48c152b559e0af3ea1a7b65 (patch)
tree536ce3416fd908f0506899b371d86fb21171078c /drivers/tty/ehv_bytechan.c
parentfcb8ce5cfe30ca9ca5c9a79cdfe26d1993e65e0c (diff)
tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver
The ePAPR embedded hypervisor specification provides an API for "byte channels", which are serial-like virtual devices for sending and receiving streams of bytes. This driver provides Linux kernel support for byte channels via three distinct interfaces: 1) An early-console (udbg) driver. This provides early console output through a byte channel. The byte channel handle must be specified in a Kconfig option. 2) A normal console driver. Output is sent to the byte channel designated for stdout in the device tree. The console driver is for handling kernel printk calls. 3) A tty driver, which is used to handle user-space input and output. The byte channel used for the console is designated as the default tty. Signed-off-by: Timur Tabi <timur@freescale.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty/ehv_bytechan.c')
-rw-r--r--drivers/tty/ehv_bytechan.c888
1 files changed, 888 insertions, 0 deletions
diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c
new file mode 100644
index 000000000000..e67f70bbf0ac
--- /dev/null
+++ b/drivers/tty/ehv_bytechan.c
@@ -0,0 +1,888 @@
1/* 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
229 /* Check if we're running as a guest of a hypervisor */
230 if (!(mfmsr() & MSR_GS))
231 return;
232
233 /* Verify the byte channel handle */
234 ret = ev_byte_channel_poll(CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE,
235 &rx_count, &tx_count);
236 if (ret)
237 return;
238
239 udbg_putc = ehv_bc_udbg_putc;
240 register_early_udbg_console();
241
242 udbg_printf("ehv-bc: early console using byte channel handle %u\n",
243 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
244}
245
246#endif
247
248/****************************** CONSOLE DRIVER ******************************/
249
250static struct tty_driver *ehv_bc_driver;
251
252/*
253 * Byte channel console sending worker function.
254 *
255 * For consoles, if the output buffer is full, we should just spin until it
256 * clears.
257 */
258static int ehv_bc_console_byte_channel_send(unsigned int handle, const char *s,
259 unsigned int count)
260{
261 unsigned int len;
262 int ret = 0;
263
264 while (count) {
265 len = min_t(unsigned int, count, EV_BYTE_CHANNEL_MAX_BYTES);
266 do {
267 ret = ev_byte_channel_send(handle, &len, s);
268 } while (ret == EV_EAGAIN);
269 count -= len;
270 s += len;
271 }
272
273 return ret;
274}
275
276/*
277 * write a string to the console
278 *
279 * This function gets called to write a string from the kernel, typically from
280 * a printk(). This function spins until all data is written.
281 *
282 * We copy the data to a temporary buffer because we need to insert a \r in
283 * front of every \n. It's more efficient to copy the data to the buffer than
284 * it is to make multiple hcalls for each character or each newline.
285 */
286static void ehv_bc_console_write(struct console *co, const char *s,
287 unsigned int count)
288{
289 unsigned int handle = (unsigned int)co->data;
290 char s2[EV_BYTE_CHANNEL_MAX_BYTES];
291 unsigned int i, j = 0;
292 char c;
293
294 for (i = 0; i < count; i++) {
295 c = *s++;
296
297 if (c == '\n')
298 s2[j++] = '\r';
299
300 s2[j++] = c;
301 if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) {
302 if (ehv_bc_console_byte_channel_send(handle, s2, j))
303 return;
304 j = 0;
305 }
306 }
307
308 if (j)
309 ehv_bc_console_byte_channel_send(handle, s2, j);
310}
311
312/*
313 * When /dev/console is opened, the kernel iterates the console list looking
314 * for one with ->device and then calls that method. On success, it expects
315 * the passed-in int* to contain the minor number to use.
316 */
317static struct tty_driver *ehv_bc_console_device(struct console *co, int *index)
318{
319 *index = co->index;
320
321 return ehv_bc_driver;
322}
323
324static struct console ehv_bc_console = {
325 .name = "ttyEHV",
326 .write = ehv_bc_console_write,
327 .device = ehv_bc_console_device,
328 .flags = CON_PRINTBUFFER | CON_ENABLED,
329};
330
331/*
332 * Console initialization
333 *
334 * This is the first function that is called after the device tree is
335 * available, so here is where we determine the byte channel handle and IRQ for
336 * stdout/stdin, even though that information is used by the tty and character
337 * drivers.
338 */
339static int __init ehv_bc_console_init(void)
340{
341 if (!find_console_handle()) {
342 pr_debug("ehv-bc: stdout is not a byte channel\n");
343 return -ENODEV;
344 }
345
346#ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC
347 /* Print a friendly warning if the user chose the wrong byte channel
348 * handle for udbg.
349 */
350 if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE)
351 pr_warning("ehv-bc: udbg handle %u is not the stdout handle\n",
352 CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE);
353#endif
354
355 ehv_bc_console.data = (void *)stdout_bc;
356
357 /* add_preferred_console() must be called before register_console(),
358 otherwise it won't work. However, we don't want to enumerate all the
359 byte channels here, either, since we only care about one. */
360
361 add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL);
362 register_console(&ehv_bc_console);
363
364 pr_info("ehv-bc: registered console driver for byte channel %u\n",
365 stdout_bc);
366
367 return 0;
368}
369console_initcall(ehv_bc_console_init);
370
371/******************************** TTY DRIVER ********************************/
372
373/*
374 * byte channel receive interupt handler
375 *
376 * This ISR is called whenever data is available on a byte channel.
377 */
378static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
379{
380 struct ehv_bc_data *bc = data;
381 struct tty_struct *ttys = tty_port_tty_get(&bc->port);
382 unsigned int rx_count, tx_count, len;
383 int count;
384 char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
385 int ret;
386
387 /* ttys could be NULL during a hangup */
388 if (!ttys)
389 return IRQ_HANDLED;
390
391 /* Find out how much data needs to be read, and then ask the TTY layer
392 * if it can handle that much. We want to ensure that every byte we
393 * read from the byte channel will be accepted by the TTY layer.
394 */
395 ev_byte_channel_poll(bc->handle, &rx_count, &tx_count);
396 count = tty_buffer_request_room(ttys, rx_count);
397
398 /* 'count' is the maximum amount of data the TTY layer can accept at
399 * this time. However, during testing, I was never able to get 'count'
400 * to be less than 'rx_count'. I'm not sure whether I'm calling it
401 * correctly.
402 */
403
404 while (count > 0) {
405 len = min_t(unsigned int, count, sizeof(buffer));
406
407 /* Read some data from the byte channel. This function will
408 * never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes.
409 */
410 ev_byte_channel_receive(bc->handle, &len, buffer);
411
412 /* 'len' is now the amount of data that's been received. 'len'
413 * can't be zero, and most likely it's equal to one.
414 */
415
416 /* Pass the received data to the tty layer. */
417 ret = tty_insert_flip_string(ttys, buffer, len);
418
419 /* 'ret' is the number of bytes that the TTY layer accepted.
420 * If it's not equal to 'len', then it means the buffer is
421 * full, which should never happen. If it does happen, we can
422 * exit gracefully, but we drop the last 'len - ret' characters
423 * that we read from the byte channel.
424 */
425 if (ret != len)
426 break;
427
428 count -= len;
429 }
430
431 /* Tell the tty layer that we're done. */
432 tty_flip_buffer_push(ttys);
433
434 tty_kref_put(ttys);
435
436 return IRQ_HANDLED;
437}
438
439/*
440 * dequeue the transmit buffer to the hypervisor
441 *
442 * This function, which can be called in interrupt context, dequeues as much
443 * data as possible from the transmit buffer to the byte channel.
444 */
445static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc)
446{
447 unsigned int count;
448 unsigned int len, ret;
449 unsigned long flags;
450
451 do {
452 spin_lock_irqsave(&bc->lock, flags);
453 len = min_t(unsigned int,
454 CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
455 EV_BYTE_CHANNEL_MAX_BYTES);
456
457 ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail);
458
459 /* 'len' is valid only if the return code is 0 or EV_EAGAIN */
460 if (!ret || (ret == EV_EAGAIN))
461 bc->tail = (bc->tail + len) & (BUF_SIZE - 1);
462
463 count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE);
464 spin_unlock_irqrestore(&bc->lock, flags);
465 } while (count && !ret);
466
467 spin_lock_irqsave(&bc->lock, flags);
468 if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE))
469 /*
470 * If we haven't emptied the buffer, then enable the TX IRQ.
471 * We'll get an interrupt when there's more room in the
472 * hypervisor's output buffer.
473 */
474 enable_tx_interrupt(bc);
475 else
476 disable_tx_interrupt(bc);
477 spin_unlock_irqrestore(&bc->lock, flags);
478}
479
480/*
481 * byte channel transmit interupt handler
482 *
483 * This ISR is called whenever space becomes available for transmitting
484 * characters on a byte channel.
485 */
486static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
487{
488 struct ehv_bc_data *bc = data;
489 struct tty_struct *ttys = tty_port_tty_get(&bc->port);
490
491 ehv_bc_tx_dequeue(bc);
492 if (ttys) {
493 tty_wakeup(ttys);
494 tty_kref_put(ttys);
495 }
496
497 return IRQ_HANDLED;
498}
499
500/*
501 * This function is called when the tty layer has data for us send. We store
502 * the data first in a circular buffer, and then dequeue as much of that data
503 * as possible.
504 *
505 * We don't need to worry about whether there is enough room in the buffer for
506 * all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty
507 * layer how much data it can safely send to us. We guarantee that
508 * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
509 * too much data.
510 */
511static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s,
512 int count)
513{
514 struct ehv_bc_data *bc = ttys->driver_data;
515 unsigned long flags;
516 unsigned int len;
517 unsigned int written = 0;
518
519 while (1) {
520 spin_lock_irqsave(&bc->lock, flags);
521 len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
522 if (count < len)
523 len = count;
524 if (len) {
525 memcpy(bc->buf + bc->head, s, len);
526 bc->head = (bc->head + len) & (BUF_SIZE - 1);
527 }
528 spin_unlock_irqrestore(&bc->lock, flags);
529 if (!len)
530 break;
531
532 s += len;
533 count -= len;
534 written += len;
535 }
536
537 ehv_bc_tx_dequeue(bc);
538
539 return written;
540}
541
542/*
543 * This function can be called multiple times for a given tty_struct, which is
544 * why we initialize bc->ttys in ehv_bc_tty_port_activate() instead.
545 *
546 * The tty layer will still call this function even if the device was not
547 * registered (i.e. tty_register_device() was not called). This happens
548 * because tty_register_device() is optional and some legacy drivers don't
549 * use it. So we need to check for that.
550 */
551static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp)
552{
553 struct ehv_bc_data *bc = &bcs[ttys->index];
554
555 if (!bc->dev)
556 return -ENODEV;
557
558 return tty_port_open(&bc->port, ttys, filp);
559}
560
561/*
562 * Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will
563 * still call this function to close the tty device. So we can't assume that
564 * the tty port has been initialized.
565 */
566static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp)
567{
568 struct ehv_bc_data *bc = &bcs[ttys->index];
569
570 if (bc->dev)
571 tty_port_close(&bc->port, ttys, filp);
572}
573
574/*
575 * Return the amount of space in the output buffer
576 *
577 * This is actually a contract between the driver and the tty layer outlining
578 * how much write room the driver can guarantee will be sent OR BUFFERED. This
579 * driver MUST honor the return value.
580 */
581static int ehv_bc_tty_write_room(struct tty_struct *ttys)
582{
583 struct ehv_bc_data *bc = ttys->driver_data;
584 unsigned long flags;
585 int count;
586
587 spin_lock_irqsave(&bc->lock, flags);
588 count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
589 spin_unlock_irqrestore(&bc->lock, flags);
590
591 return count;
592}
593
594/*
595 * Stop sending data to the tty layer
596 *
597 * This function is called when the tty layer's input buffers are getting full,
598 * so the driver should stop sending it data. The easiest way to do this is to
599 * disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being
600 * called.
601 *
602 * The hypervisor will continue to queue up any incoming data. If there is any
603 * data in the queue when the RX interrupt is enabled, we'll immediately get an
604 * RX interrupt.
605 */
606static void ehv_bc_tty_throttle(struct tty_struct *ttys)
607{
608 struct ehv_bc_data *bc = ttys->driver_data;
609
610 disable_irq(bc->rx_irq);
611}
612
613/*
614 * Resume sending data to the tty layer
615 *
616 * This function is called after previously calling ehv_bc_tty_throttle(). The
617 * tty layer's input buffers now have more room, so the driver can resume
618 * sending it data.
619 */
620static void ehv_bc_tty_unthrottle(struct tty_struct *ttys)
621{
622 struct ehv_bc_data *bc = ttys->driver_data;
623
624 /* If there is any data in the queue when the RX interrupt is enabled,
625 * we'll immediately get an RX interrupt.
626 */
627 enable_irq(bc->rx_irq);
628}
629
630static void ehv_bc_tty_hangup(struct tty_struct *ttys)
631{
632 struct ehv_bc_data *bc = ttys->driver_data;
633
634 ehv_bc_tx_dequeue(bc);
635 tty_port_hangup(&bc->port);
636}
637
638/*
639 * TTY driver operations
640 *
641 * If we could ask the hypervisor how much data is still in the TX buffer, or
642 * at least how big the TX buffers are, then we could implement the
643 * .wait_until_sent and .chars_in_buffer functions.
644 */
645static const struct tty_operations ehv_bc_ops = {
646 .open = ehv_bc_tty_open,
647 .close = ehv_bc_tty_close,
648 .write = ehv_bc_tty_write,
649 .write_room = ehv_bc_tty_write_room,
650 .throttle = ehv_bc_tty_throttle,
651 .unthrottle = ehv_bc_tty_unthrottle,
652 .hangup = ehv_bc_tty_hangup,
653};
654
655/*
656 * initialize the TTY port
657 *
658 * This function will only be called once, no matter how many times
659 * ehv_bc_tty_open() is called. That's why we register the ISR here, and also
660 * why we initialize tty_struct-related variables here.
661 */
662static int ehv_bc_tty_port_activate(struct tty_port *port,
663 struct tty_struct *ttys)
664{
665 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
666 int ret;
667
668 ttys->driver_data = bc;
669
670 ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc);
671 if (ret < 0) {
672 dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n",
673 bc->rx_irq, ret);
674 return ret;
675 }
676
677 /* request_irq also enables the IRQ */
678 bc->tx_irq_enabled = 1;
679
680 ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc);
681 if (ret < 0) {
682 dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n",
683 bc->tx_irq, ret);
684 free_irq(bc->rx_irq, bc);
685 return ret;
686 }
687
688 /* The TX IRQ is enabled only when we can't write all the data to the
689 * byte channel at once, so by default it's disabled.
690 */
691 disable_tx_interrupt(bc);
692
693 return 0;
694}
695
696static void ehv_bc_tty_port_shutdown(struct tty_port *port)
697{
698 struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port);
699
700 free_irq(bc->tx_irq, bc);
701 free_irq(bc->rx_irq, bc);
702}
703
704static const struct tty_port_operations ehv_bc_tty_port_ops = {
705 .activate = ehv_bc_tty_port_activate,
706 .shutdown = ehv_bc_tty_port_shutdown,
707};
708
709static int __devinit ehv_bc_tty_probe(struct platform_device *pdev)
710{
711 struct device_node *np = pdev->dev.of_node;
712 struct ehv_bc_data *bc;
713 const uint32_t *iprop;
714 unsigned int handle;
715 int ret;
716 static unsigned int index = 1;
717 unsigned int i;
718
719 iprop = of_get_property(np, "hv-handle", NULL);
720 if (!iprop) {
721 dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n",
722 np->name);
723 return -ENODEV;
724 }
725
726 /* We already told the console layer that the index for the console
727 * device is zero, so we need to make sure that we use that index when
728 * we probe the console byte channel node.
729 */
730 handle = be32_to_cpu(*iprop);
731 i = (handle == stdout_bc) ? 0 : index++;
732 bc = &bcs[i];
733
734 bc->handle = handle;
735 bc->head = 0;
736 bc->tail = 0;
737 spin_lock_init(&bc->lock);
738
739 bc->rx_irq = irq_of_parse_and_map(np, 0);
740 bc->tx_irq = irq_of_parse_and_map(np, 1);
741 if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) {
742 dev_err(&pdev->dev, "no 'interrupts' property in %s node\n",
743 np->name);
744 ret = -ENODEV;
745 goto error;
746 }
747
748 bc->dev = tty_register_device(ehv_bc_driver, i, &pdev->dev);
749 if (IS_ERR(bc->dev)) {
750 ret = PTR_ERR(bc->dev);
751 dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret);
752 goto error;
753 }
754
755 tty_port_init(&bc->port);
756 bc->port.ops = &ehv_bc_tty_port_ops;
757
758 dev_set_drvdata(&pdev->dev, bc);
759
760 dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n",
761 ehv_bc_driver->name, i, bc->handle);
762
763 return 0;
764
765error:
766 irq_dispose_mapping(bc->tx_irq);
767 irq_dispose_mapping(bc->rx_irq);
768
769 memset(bc, 0, sizeof(struct ehv_bc_data));
770 return ret;
771}
772
773static int ehv_bc_tty_remove(struct platform_device *pdev)
774{
775 struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev);
776
777 tty_unregister_device(ehv_bc_driver, bc - bcs);
778
779 irq_dispose_mapping(bc->tx_irq);
780 irq_dispose_mapping(bc->rx_irq);
781
782 return 0;
783}
784
785static const struct of_device_id ehv_bc_tty_of_ids[] = {
786 { .compatible = "epapr,hv-byte-channel" },
787 {}
788};
789
790static struct platform_driver ehv_bc_tty_driver = {
791 .driver = {
792 .owner = THIS_MODULE,
793 .name = "ehv-bc",
794 .of_match_table = ehv_bc_tty_of_ids,
795 },
796 .probe = ehv_bc_tty_probe,
797 .remove = ehv_bc_tty_remove,
798};
799
800/**
801 * ehv_bc_init - ePAPR hypervisor byte channel driver initialization
802 *
803 * This function is called when this module is loaded.
804 */
805static int __init ehv_bc_init(void)
806{
807 struct device_node *np;
808 unsigned int count = 0; /* Number of elements in bcs[] */
809 int ret;
810
811 pr_info("ePAPR hypervisor byte channel driver\n");
812
813 /* Count the number of byte channels */
814 for_each_compatible_node(np, NULL, "epapr,hv-byte-channel")
815 count++;
816
817 if (!count)
818 return -ENODEV;
819
820 /* The array index of an element in bcs[] is the same as the tty index
821 * for that element. If you know the address of an element in the
822 * array, then you can use pointer math (e.g. "bc - bcs") to get its
823 * tty index.
824 */
825 bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL);
826 if (!bcs)
827 return -ENOMEM;
828
829 ehv_bc_driver = alloc_tty_driver(count);
830 if (!ehv_bc_driver) {
831 ret = -ENOMEM;
832 goto error;
833 }
834
835 ehv_bc_driver->owner = THIS_MODULE;
836 ehv_bc_driver->driver_name = "ehv-bc";
837 ehv_bc_driver->name = ehv_bc_console.name;
838 ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE;
839 ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE;
840 ehv_bc_driver->init_termios = tty_std_termios;
841 ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
842 tty_set_operations(ehv_bc_driver, &ehv_bc_ops);
843
844 ret = tty_register_driver(ehv_bc_driver);
845 if (ret) {
846 pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret);
847 goto error;
848 }
849
850 ret = platform_driver_register(&ehv_bc_tty_driver);
851 if (ret) {
852 pr_err("ehv-bc: could not register platform driver (ret=%i)\n",
853 ret);
854 goto error;
855 }
856
857 return 0;
858
859error:
860 if (ehv_bc_driver) {
861 tty_unregister_driver(ehv_bc_driver);
862 put_tty_driver(ehv_bc_driver);
863 }
864
865 kfree(bcs);
866
867 return ret;
868}
869
870
871/**
872 * ehv_bc_exit - ePAPR hypervisor byte channel driver termination
873 *
874 * This function is called when this driver is unloaded.
875 */
876static void __exit ehv_bc_exit(void)
877{
878 tty_unregister_driver(ehv_bc_driver);
879 put_tty_driver(ehv_bc_driver);
880 kfree(bcs);
881}
882
883module_init(ehv_bc_init);
884module_exit(ehv_bc_exit);
885
886MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
887MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
888MODULE_LICENSE("GPL v2");