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dcd83aaf TT |
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 | ||
dcd83aaf TT |
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 | { | |
191c5cf1 | 285 | unsigned int handle = (uintptr_t)co->data; |
dcd83aaf TT |
286 | char s2[EV_BYTE_CHANNEL_MAX_BYTES]; |
287 | unsigned int i, j = 0; | |
288 | char c; | |
289 | ||
290 | for (i = 0; i < count; i++) { | |
291 | c = *s++; | |
292 | ||
293 | if (c == '\n') | |
294 | s2[j++] = '\r'; | |
295 | ||
296 | s2[j++] = c; | |
297 | if (j >= (EV_BYTE_CHANNEL_MAX_BYTES - 1)) { | |
298 | if (ehv_bc_console_byte_channel_send(handle, s2, j)) | |
299 | return; | |
300 | j = 0; | |
301 | } | |
302 | } | |
303 | ||
304 | if (j) | |
305 | ehv_bc_console_byte_channel_send(handle, s2, j); | |
306 | } | |
307 | ||
308 | /* | |
309 | * When /dev/console is opened, the kernel iterates the console list looking | |
310 | * for one with ->device and then calls that method. On success, it expects | |
311 | * the passed-in int* to contain the minor number to use. | |
312 | */ | |
313 | static struct tty_driver *ehv_bc_console_device(struct console *co, int *index) | |
314 | { | |
315 | *index = co->index; | |
316 | ||
317 | return ehv_bc_driver; | |
318 | } | |
319 | ||
320 | static struct console ehv_bc_console = { | |
321 | .name = "ttyEHV", | |
322 | .write = ehv_bc_console_write, | |
323 | .device = ehv_bc_console_device, | |
324 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
325 | }; | |
326 | ||
327 | /* | |
328 | * Console initialization | |
329 | * | |
330 | * This is the first function that is called after the device tree is | |
331 | * available, so here is where we determine the byte channel handle and IRQ for | |
332 | * stdout/stdin, even though that information is used by the tty and character | |
333 | * drivers. | |
334 | */ | |
335 | static int __init ehv_bc_console_init(void) | |
336 | { | |
337 | if (!find_console_handle()) { | |
338 | pr_debug("ehv-bc: stdout is not a byte channel\n"); | |
339 | return -ENODEV; | |
340 | } | |
341 | ||
342 | #ifdef CONFIG_PPC_EARLY_DEBUG_EHV_BC | |
343 | /* Print a friendly warning if the user chose the wrong byte channel | |
344 | * handle for udbg. | |
345 | */ | |
346 | if (stdout_bc != CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE) | |
347 | pr_warning("ehv-bc: udbg handle %u is not the stdout handle\n", | |
348 | CONFIG_PPC_EARLY_DEBUG_EHV_BC_HANDLE); | |
349 | #endif | |
350 | ||
191c5cf1 | 351 | ehv_bc_console.data = (void *)(uintptr_t)stdout_bc; |
dcd83aaf TT |
352 | |
353 | /* add_preferred_console() must be called before register_console(), | |
354 | otherwise it won't work. However, we don't want to enumerate all the | |
355 | byte channels here, either, since we only care about one. */ | |
356 | ||
357 | add_preferred_console(ehv_bc_console.name, ehv_bc_console.index, NULL); | |
358 | register_console(&ehv_bc_console); | |
359 | ||
360 | pr_info("ehv-bc: registered console driver for byte channel %u\n", | |
361 | stdout_bc); | |
362 | ||
363 | return 0; | |
364 | } | |
365 | console_initcall(ehv_bc_console_init); | |
366 | ||
367 | /******************************** TTY DRIVER ********************************/ | |
368 | ||
369 | /* | |
370 | * byte channel receive interupt handler | |
371 | * | |
372 | * This ISR is called whenever data is available on a byte channel. | |
373 | */ | |
374 | static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data) | |
375 | { | |
376 | struct ehv_bc_data *bc = data; | |
377 | struct tty_struct *ttys = tty_port_tty_get(&bc->port); | |
378 | unsigned int rx_count, tx_count, len; | |
379 | int count; | |
380 | char buffer[EV_BYTE_CHANNEL_MAX_BYTES]; | |
381 | int ret; | |
382 | ||
383 | /* ttys could be NULL during a hangup */ | |
384 | if (!ttys) | |
385 | return IRQ_HANDLED; | |
386 | ||
387 | /* Find out how much data needs to be read, and then ask the TTY layer | |
388 | * if it can handle that much. We want to ensure that every byte we | |
389 | * read from the byte channel will be accepted by the TTY layer. | |
390 | */ | |
391 | ev_byte_channel_poll(bc->handle, &rx_count, &tx_count); | |
392 | count = tty_buffer_request_room(ttys, rx_count); | |
393 | ||
394 | /* 'count' is the maximum amount of data the TTY layer can accept at | |
395 | * this time. However, during testing, I was never able to get 'count' | |
396 | * to be less than 'rx_count'. I'm not sure whether I'm calling it | |
397 | * correctly. | |
398 | */ | |
399 | ||
400 | while (count > 0) { | |
401 | len = min_t(unsigned int, count, sizeof(buffer)); | |
402 | ||
403 | /* Read some data from the byte channel. This function will | |
404 | * never return more than EV_BYTE_CHANNEL_MAX_BYTES bytes. | |
405 | */ | |
406 | ev_byte_channel_receive(bc->handle, &len, buffer); | |
407 | ||
408 | /* 'len' is now the amount of data that's been received. 'len' | |
409 | * can't be zero, and most likely it's equal to one. | |
410 | */ | |
411 | ||
412 | /* Pass the received data to the tty layer. */ | |
413 | ret = tty_insert_flip_string(ttys, buffer, len); | |
414 | ||
415 | /* 'ret' is the number of bytes that the TTY layer accepted. | |
416 | * If it's not equal to 'len', then it means the buffer is | |
417 | * full, which should never happen. If it does happen, we can | |
418 | * exit gracefully, but we drop the last 'len - ret' characters | |
419 | * that we read from the byte channel. | |
420 | */ | |
421 | if (ret != len) | |
422 | break; | |
423 | ||
424 | count -= len; | |
425 | } | |
426 | ||
427 | /* Tell the tty layer that we're done. */ | |
428 | tty_flip_buffer_push(ttys); | |
429 | ||
430 | tty_kref_put(ttys); | |
431 | ||
432 | return IRQ_HANDLED; | |
433 | } | |
434 | ||
435 | /* | |
436 | * dequeue the transmit buffer to the hypervisor | |
437 | * | |
438 | * This function, which can be called in interrupt context, dequeues as much | |
439 | * data as possible from the transmit buffer to the byte channel. | |
440 | */ | |
441 | static void ehv_bc_tx_dequeue(struct ehv_bc_data *bc) | |
442 | { | |
443 | unsigned int count; | |
444 | unsigned int len, ret; | |
445 | unsigned long flags; | |
446 | ||
447 | do { | |
448 | spin_lock_irqsave(&bc->lock, flags); | |
449 | len = min_t(unsigned int, | |
450 | CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE), | |
451 | EV_BYTE_CHANNEL_MAX_BYTES); | |
452 | ||
453 | ret = ev_byte_channel_send(bc->handle, &len, bc->buf + bc->tail); | |
454 | ||
455 | /* 'len' is valid only if the return code is 0 or EV_EAGAIN */ | |
456 | if (!ret || (ret == EV_EAGAIN)) | |
457 | bc->tail = (bc->tail + len) & (BUF_SIZE - 1); | |
458 | ||
459 | count = CIRC_CNT(bc->head, bc->tail, BUF_SIZE); | |
460 | spin_unlock_irqrestore(&bc->lock, flags); | |
461 | } while (count && !ret); | |
462 | ||
463 | spin_lock_irqsave(&bc->lock, flags); | |
464 | if (CIRC_CNT(bc->head, bc->tail, BUF_SIZE)) | |
465 | /* | |
466 | * If we haven't emptied the buffer, then enable the TX IRQ. | |
467 | * We'll get an interrupt when there's more room in the | |
468 | * hypervisor's output buffer. | |
469 | */ | |
470 | enable_tx_interrupt(bc); | |
471 | else | |
472 | disable_tx_interrupt(bc); | |
473 | spin_unlock_irqrestore(&bc->lock, flags); | |
474 | } | |
475 | ||
476 | /* | |
477 | * byte channel transmit interupt handler | |
478 | * | |
479 | * This ISR is called whenever space becomes available for transmitting | |
480 | * characters on a byte channel. | |
481 | */ | |
482 | static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data) | |
483 | { | |
484 | struct ehv_bc_data *bc = data; | |
485 | struct tty_struct *ttys = tty_port_tty_get(&bc->port); | |
486 | ||
487 | ehv_bc_tx_dequeue(bc); | |
488 | if (ttys) { | |
489 | tty_wakeup(ttys); | |
490 | tty_kref_put(ttys); | |
491 | } | |
492 | ||
493 | return IRQ_HANDLED; | |
494 | } | |
495 | ||
496 | /* | |
497 | * This function is called when the tty layer has data for us send. We store | |
498 | * the data first in a circular buffer, and then dequeue as much of that data | |
499 | * as possible. | |
500 | * | |
501 | * We don't need to worry about whether there is enough room in the buffer for | |
502 | * all the data. The purpose of ehv_bc_tty_write_room() is to tell the tty | |
503 | * layer how much data it can safely send to us. We guarantee that | |
504 | * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us | |
505 | * too much data. | |
506 | */ | |
507 | static int ehv_bc_tty_write(struct tty_struct *ttys, const unsigned char *s, | |
508 | int count) | |
509 | { | |
510 | struct ehv_bc_data *bc = ttys->driver_data; | |
511 | unsigned long flags; | |
512 | unsigned int len; | |
513 | unsigned int written = 0; | |
514 | ||
515 | while (1) { | |
516 | spin_lock_irqsave(&bc->lock, flags); | |
517 | len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE); | |
518 | if (count < len) | |
519 | len = count; | |
520 | if (len) { | |
521 | memcpy(bc->buf + bc->head, s, len); | |
522 | bc->head = (bc->head + len) & (BUF_SIZE - 1); | |
523 | } | |
524 | spin_unlock_irqrestore(&bc->lock, flags); | |
525 | if (!len) | |
526 | break; | |
527 | ||
528 | s += len; | |
529 | count -= len; | |
530 | written += len; | |
531 | } | |
532 | ||
533 | ehv_bc_tx_dequeue(bc); | |
534 | ||
535 | return written; | |
536 | } | |
537 | ||
538 | /* | |
539 | * This function can be called multiple times for a given tty_struct, which is | |
540 | * why we initialize bc->ttys in ehv_bc_tty_port_activate() instead. | |
541 | * | |
542 | * The tty layer will still call this function even if the device was not | |
543 | * registered (i.e. tty_register_device() was not called). This happens | |
544 | * because tty_register_device() is optional and some legacy drivers don't | |
545 | * use it. So we need to check for that. | |
546 | */ | |
547 | static int ehv_bc_tty_open(struct tty_struct *ttys, struct file *filp) | |
548 | { | |
549 | struct ehv_bc_data *bc = &bcs[ttys->index]; | |
550 | ||
551 | if (!bc->dev) | |
552 | return -ENODEV; | |
553 | ||
554 | return tty_port_open(&bc->port, ttys, filp); | |
555 | } | |
556 | ||
557 | /* | |
558 | * Amazingly, if ehv_bc_tty_open() returns an error code, the tty layer will | |
559 | * still call this function to close the tty device. So we can't assume that | |
560 | * the tty port has been initialized. | |
561 | */ | |
562 | static void ehv_bc_tty_close(struct tty_struct *ttys, struct file *filp) | |
563 | { | |
564 | struct ehv_bc_data *bc = &bcs[ttys->index]; | |
565 | ||
566 | if (bc->dev) | |
567 | tty_port_close(&bc->port, ttys, filp); | |
568 | } | |
569 | ||
570 | /* | |
571 | * Return the amount of space in the output buffer | |
572 | * | |
573 | * This is actually a contract between the driver and the tty layer outlining | |
574 | * how much write room the driver can guarantee will be sent OR BUFFERED. This | |
575 | * driver MUST honor the return value. | |
576 | */ | |
577 | static int ehv_bc_tty_write_room(struct tty_struct *ttys) | |
578 | { | |
579 | struct ehv_bc_data *bc = ttys->driver_data; | |
580 | unsigned long flags; | |
581 | int count; | |
582 | ||
583 | spin_lock_irqsave(&bc->lock, flags); | |
584 | count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE); | |
585 | spin_unlock_irqrestore(&bc->lock, flags); | |
586 | ||
587 | return count; | |
588 | } | |
589 | ||
590 | /* | |
591 | * Stop sending data to the tty layer | |
592 | * | |
593 | * This function is called when the tty layer's input buffers are getting full, | |
594 | * so the driver should stop sending it data. The easiest way to do this is to | |
595 | * disable the RX IRQ, which will prevent ehv_bc_tty_rx_isr() from being | |
596 | * called. | |
597 | * | |
598 | * The hypervisor will continue to queue up any incoming data. If there is any | |
599 | * data in the queue when the RX interrupt is enabled, we'll immediately get an | |
600 | * RX interrupt. | |
601 | */ | |
602 | static void ehv_bc_tty_throttle(struct tty_struct *ttys) | |
603 | { | |
604 | struct ehv_bc_data *bc = ttys->driver_data; | |
605 | ||
606 | disable_irq(bc->rx_irq); | |
607 | } | |
608 | ||
609 | /* | |
610 | * Resume sending data to the tty layer | |
611 | * | |
612 | * This function is called after previously calling ehv_bc_tty_throttle(). The | |
613 | * tty layer's input buffers now have more room, so the driver can resume | |
614 | * sending it data. | |
615 | */ | |
616 | static void ehv_bc_tty_unthrottle(struct tty_struct *ttys) | |
617 | { | |
618 | struct ehv_bc_data *bc = ttys->driver_data; | |
619 | ||
620 | /* If there is any data in the queue when the RX interrupt is enabled, | |
621 | * we'll immediately get an RX interrupt. | |
622 | */ | |
623 | enable_irq(bc->rx_irq); | |
624 | } | |
625 | ||
626 | static void ehv_bc_tty_hangup(struct tty_struct *ttys) | |
627 | { | |
628 | struct ehv_bc_data *bc = ttys->driver_data; | |
629 | ||
630 | ehv_bc_tx_dequeue(bc); | |
631 | tty_port_hangup(&bc->port); | |
632 | } | |
633 | ||
634 | /* | |
635 | * TTY driver operations | |
636 | * | |
637 | * If we could ask the hypervisor how much data is still in the TX buffer, or | |
638 | * at least how big the TX buffers are, then we could implement the | |
639 | * .wait_until_sent and .chars_in_buffer functions. | |
640 | */ | |
641 | static const struct tty_operations ehv_bc_ops = { | |
642 | .open = ehv_bc_tty_open, | |
643 | .close = ehv_bc_tty_close, | |
644 | .write = ehv_bc_tty_write, | |
645 | .write_room = ehv_bc_tty_write_room, | |
646 | .throttle = ehv_bc_tty_throttle, | |
647 | .unthrottle = ehv_bc_tty_unthrottle, | |
648 | .hangup = ehv_bc_tty_hangup, | |
649 | }; | |
650 | ||
651 | /* | |
652 | * initialize the TTY port | |
653 | * | |
654 | * This function will only be called once, no matter how many times | |
655 | * ehv_bc_tty_open() is called. That's why we register the ISR here, and also | |
656 | * why we initialize tty_struct-related variables here. | |
657 | */ | |
658 | static int ehv_bc_tty_port_activate(struct tty_port *port, | |
659 | struct tty_struct *ttys) | |
660 | { | |
661 | struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port); | |
662 | int ret; | |
663 | ||
664 | ttys->driver_data = bc; | |
665 | ||
666 | ret = request_irq(bc->rx_irq, ehv_bc_tty_rx_isr, 0, "ehv-bc", bc); | |
667 | if (ret < 0) { | |
668 | dev_err(bc->dev, "could not request rx irq %u (ret=%i)\n", | |
669 | bc->rx_irq, ret); | |
670 | return ret; | |
671 | } | |
672 | ||
673 | /* request_irq also enables the IRQ */ | |
674 | bc->tx_irq_enabled = 1; | |
675 | ||
676 | ret = request_irq(bc->tx_irq, ehv_bc_tty_tx_isr, 0, "ehv-bc", bc); | |
677 | if (ret < 0) { | |
678 | dev_err(bc->dev, "could not request tx irq %u (ret=%i)\n", | |
679 | bc->tx_irq, ret); | |
680 | free_irq(bc->rx_irq, bc); | |
681 | return ret; | |
682 | } | |
683 | ||
684 | /* The TX IRQ is enabled only when we can't write all the data to the | |
685 | * byte channel at once, so by default it's disabled. | |
686 | */ | |
687 | disable_tx_interrupt(bc); | |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
692 | static void ehv_bc_tty_port_shutdown(struct tty_port *port) | |
693 | { | |
694 | struct ehv_bc_data *bc = container_of(port, struct ehv_bc_data, port); | |
695 | ||
696 | free_irq(bc->tx_irq, bc); | |
697 | free_irq(bc->rx_irq, bc); | |
698 | } | |
699 | ||
700 | static const struct tty_port_operations ehv_bc_tty_port_ops = { | |
701 | .activate = ehv_bc_tty_port_activate, | |
702 | .shutdown = ehv_bc_tty_port_shutdown, | |
703 | }; | |
704 | ||
705 | static int __devinit ehv_bc_tty_probe(struct platform_device *pdev) | |
706 | { | |
707 | struct device_node *np = pdev->dev.of_node; | |
708 | struct ehv_bc_data *bc; | |
709 | const uint32_t *iprop; | |
710 | unsigned int handle; | |
711 | int ret; | |
712 | static unsigned int index = 1; | |
713 | unsigned int i; | |
714 | ||
715 | iprop = of_get_property(np, "hv-handle", NULL); | |
716 | if (!iprop) { | |
717 | dev_err(&pdev->dev, "no 'hv-handle' property in %s node\n", | |
718 | np->name); | |
719 | return -ENODEV; | |
720 | } | |
721 | ||
722 | /* We already told the console layer that the index for the console | |
723 | * device is zero, so we need to make sure that we use that index when | |
724 | * we probe the console byte channel node. | |
725 | */ | |
726 | handle = be32_to_cpu(*iprop); | |
727 | i = (handle == stdout_bc) ? 0 : index++; | |
728 | bc = &bcs[i]; | |
729 | ||
730 | bc->handle = handle; | |
731 | bc->head = 0; | |
732 | bc->tail = 0; | |
733 | spin_lock_init(&bc->lock); | |
734 | ||
735 | bc->rx_irq = irq_of_parse_and_map(np, 0); | |
736 | bc->tx_irq = irq_of_parse_and_map(np, 1); | |
737 | if ((bc->rx_irq == NO_IRQ) || (bc->tx_irq == NO_IRQ)) { | |
738 | dev_err(&pdev->dev, "no 'interrupts' property in %s node\n", | |
739 | np->name); | |
740 | ret = -ENODEV; | |
741 | goto error; | |
742 | } | |
743 | ||
744 | bc->dev = tty_register_device(ehv_bc_driver, i, &pdev->dev); | |
745 | if (IS_ERR(bc->dev)) { | |
746 | ret = PTR_ERR(bc->dev); | |
747 | dev_err(&pdev->dev, "could not register tty (ret=%i)\n", ret); | |
748 | goto error; | |
749 | } | |
750 | ||
751 | tty_port_init(&bc->port); | |
752 | bc->port.ops = &ehv_bc_tty_port_ops; | |
753 | ||
754 | dev_set_drvdata(&pdev->dev, bc); | |
755 | ||
756 | dev_info(&pdev->dev, "registered /dev/%s%u for byte channel %u\n", | |
757 | ehv_bc_driver->name, i, bc->handle); | |
758 | ||
759 | return 0; | |
760 | ||
761 | error: | |
762 | irq_dispose_mapping(bc->tx_irq); | |
763 | irq_dispose_mapping(bc->rx_irq); | |
764 | ||
765 | memset(bc, 0, sizeof(struct ehv_bc_data)); | |
766 | return ret; | |
767 | } | |
768 | ||
769 | static int ehv_bc_tty_remove(struct platform_device *pdev) | |
770 | { | |
771 | struct ehv_bc_data *bc = dev_get_drvdata(&pdev->dev); | |
772 | ||
773 | tty_unregister_device(ehv_bc_driver, bc - bcs); | |
774 | ||
775 | irq_dispose_mapping(bc->tx_irq); | |
776 | irq_dispose_mapping(bc->rx_irq); | |
777 | ||
778 | return 0; | |
779 | } | |
780 | ||
781 | static const struct of_device_id ehv_bc_tty_of_ids[] = { | |
782 | { .compatible = "epapr,hv-byte-channel" }, | |
783 | {} | |
784 | }; | |
785 | ||
786 | static struct platform_driver ehv_bc_tty_driver = { | |
787 | .driver = { | |
788 | .owner = THIS_MODULE, | |
789 | .name = "ehv-bc", | |
790 | .of_match_table = ehv_bc_tty_of_ids, | |
791 | }, | |
792 | .probe = ehv_bc_tty_probe, | |
793 | .remove = ehv_bc_tty_remove, | |
794 | }; | |
795 | ||
796 | /** | |
797 | * ehv_bc_init - ePAPR hypervisor byte channel driver initialization | |
798 | * | |
799 | * This function is called when this module is loaded. | |
800 | */ | |
801 | static int __init ehv_bc_init(void) | |
802 | { | |
803 | struct device_node *np; | |
804 | unsigned int count = 0; /* Number of elements in bcs[] */ | |
805 | int ret; | |
806 | ||
807 | pr_info("ePAPR hypervisor byte channel driver\n"); | |
808 | ||
809 | /* Count the number of byte channels */ | |
810 | for_each_compatible_node(np, NULL, "epapr,hv-byte-channel") | |
811 | count++; | |
812 | ||
813 | if (!count) | |
814 | return -ENODEV; | |
815 | ||
816 | /* The array index of an element in bcs[] is the same as the tty index | |
817 | * for that element. If you know the address of an element in the | |
818 | * array, then you can use pointer math (e.g. "bc - bcs") to get its | |
819 | * tty index. | |
820 | */ | |
821 | bcs = kzalloc(count * sizeof(struct ehv_bc_data), GFP_KERNEL); | |
822 | if (!bcs) | |
823 | return -ENOMEM; | |
824 | ||
825 | ehv_bc_driver = alloc_tty_driver(count); | |
826 | if (!ehv_bc_driver) { | |
827 | ret = -ENOMEM; | |
828 | goto error; | |
829 | } | |
830 | ||
831 | ehv_bc_driver->owner = THIS_MODULE; | |
832 | ehv_bc_driver->driver_name = "ehv-bc"; | |
833 | ehv_bc_driver->name = ehv_bc_console.name; | |
834 | ehv_bc_driver->type = TTY_DRIVER_TYPE_CONSOLE; | |
835 | ehv_bc_driver->subtype = SYSTEM_TYPE_CONSOLE; | |
836 | ehv_bc_driver->init_termios = tty_std_termios; | |
837 | ehv_bc_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV; | |
838 | tty_set_operations(ehv_bc_driver, &ehv_bc_ops); | |
839 | ||
840 | ret = tty_register_driver(ehv_bc_driver); | |
841 | if (ret) { | |
842 | pr_err("ehv-bc: could not register tty driver (ret=%i)\n", ret); | |
843 | goto error; | |
844 | } | |
845 | ||
846 | ret = platform_driver_register(&ehv_bc_tty_driver); | |
847 | if (ret) { | |
848 | pr_err("ehv-bc: could not register platform driver (ret=%i)\n", | |
849 | ret); | |
850 | goto error; | |
851 | } | |
852 | ||
853 | return 0; | |
854 | ||
855 | error: | |
856 | if (ehv_bc_driver) { | |
857 | tty_unregister_driver(ehv_bc_driver); | |
858 | put_tty_driver(ehv_bc_driver); | |
859 | } | |
860 | ||
861 | kfree(bcs); | |
862 | ||
863 | return ret; | |
864 | } | |
865 | ||
866 | ||
867 | /** | |
868 | * ehv_bc_exit - ePAPR hypervisor byte channel driver termination | |
869 | * | |
870 | * This function is called when this driver is unloaded. | |
871 | */ | |
872 | static void __exit ehv_bc_exit(void) | |
873 | { | |
874 | tty_unregister_driver(ehv_bc_driver); | |
875 | put_tty_driver(ehv_bc_driver); | |
876 | kfree(bcs); | |
877 | } | |
878 | ||
879 | module_init(ehv_bc_init); | |
880 | module_exit(ehv_bc_exit); | |
881 | ||
882 | MODULE_AUTHOR("Timur Tabi <timur@freescale.com>"); | |
883 | MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver"); | |
884 | MODULE_LICENSE("GPL v2"); |