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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 */ |
47 | struct 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 */ |
63 | static struct ehv_bc_data *bcs; |
64 | |
65 | /* Byte channel handle for stdout (and stdin), taken from device tree */ |
66 | static unsigned int stdout_bc; |
67 | |
68 | /* Virtual IRQ for the byte channel handle for stdin, taken from device tree */ |
69 | static 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 | */ |
89 | static 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 | |
97 | static 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 | */ |
113 | static 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 | */ |
190 | static 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 | */ |
205 | static 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 | */ |
224 | void __init udbg_init_ehv_bc(void) |
225 | { |
226 | unsigned int rx_count, tx_count; |
227 | unsigned int ret; |
228 | |
229 | /* 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 | |
246 | static 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 | */ |
254 | static 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 | */ |
282 | static void ehv_bc_console_write(struct console *co, const char *s, |
283 | unsigned int count) |
284 | { |
285 | 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)) { |
297 | if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j)) |
298 | return; |
299 | j = 0; |
300 | } |
301 | } |
302 | |
303 | if (j) |
304 | ehv_bc_console_byte_channel_send(stdout_bc, s2, j); |
305 | } |
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 | */ |
312 | static 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 | |
319 | static 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 | */ |
334 | static 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 | |
350 | /* 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 | } |
362 | console_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 | */ |
371 | static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data) |
372 | { |
373 | struct ehv_bc_data *bc = data; |
374 | unsigned int rx_count, tx_count, len; |
375 | int count; |
376 | char buffer[EV_BYTE_CHANNEL_MAX_BYTES]; |
377 | int ret; |
378 | |
379 | /* 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); |
384 | count = tty_buffer_request_room(&bc->port, rx_count); |
385 | |
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. */ |
405 | ret = tty_insert_flip_string(&bc->port, buffer, len); |
406 | |
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. */ |
420 | tty_flip_buffer_push(&bc->port); |
421 | |
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 | */ |
431 | static 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 | */ |
472 | static 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 | */ |
497 | static 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 | */ |
537 | static 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 | */ |
552 | static 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 | */ |
567 | static 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 | */ |
592 | static 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 | */ |
606 | static 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 | |
616 | static 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 | */ |
631 | static 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 | */ |
648 | static 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 | |
682 | static 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 | |
690 | static 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 | |
695 | static int ehv_bc_tty_probe(struct platform_device *pdev) |
696 | { |
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 | |
734 | 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); |
739 | 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 | |
745 | 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 | |
752 | error: |
753 | tty_port_destroy(&bc->port); |
754 | 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 | |
761 | static 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 | |
767 | tty_port_destroy(&bc->port); |
768 | irq_dispose_mapping(bc->tx_irq); |
769 | irq_dispose_mapping(bc->rx_irq); |
770 | |
771 | return 0; |
772 | } |
773 | |
774 | static const struct of_device_id ehv_bc_tty_of_ids[] = { |
775 | { .compatible = "epapr,hv-byte-channel" }, |
776 | {} |
777 | }; |
778 | |
779 | static 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 | */ |
794 | static 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 | |
824 | 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 | |
847 | error: |
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 | */ |
864 | static 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 | |
871 | module_init(ehv_bc_init); |
872 | module_exit(ehv_bc_exit); |
873 | |
874 | MODULE_AUTHOR("Timur Tabi <timur@freescale.com>"); |
875 | MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver"); |
876 | MODULE_LICENSE("GPL v2"); |
877 |
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