Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

Linux/drivers/tty/ehv_bytechan.c

  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/of_irq.h>
 36 #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 */
 48 struct 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 */
 64 static struct ehv_bc_data *bcs;
 65 
 66 /* Byte channel handle for stdout (and stdin), taken from device tree */
 67 static unsigned int stdout_bc;
 68 
 69 /* Virtual IRQ for the byte channel handle for stdin, taken from device tree */
 70 static 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  */
 90 static 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 
 98 static 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.
111  */
112 static int find_console_handle(void)
113 {
114         struct device_node *np = of_stdout;
115         const char *sprop = NULL;
116         const uint32_t *iprop;
117 
118         /* 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
120          * indicates that it's a byte channel node.
121          */
122         if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))
123                 return 0;
124 
125         stdout_irq = irq_of_parse_and_map(np, 0);
126         if (stdout_irq == NO_IRQ) {
127                 pr_err("ehv-bc: no 'interrupts' property in %s node\n", np->full_name);
128                 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);
138                 return 0;
139         }
140         stdout_bc = be32_to_cpu(*iprop);
141         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  */
156 static 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  */
171 static 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  */
190 void __init udbg_init_ehv_bc(void)
191 {
192         unsigned int rx_count, tx_count;
193         unsigned int ret;
194 
195         /* 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 
212 static 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  */
220 static 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  */
248 static void ehv_bc_console_write(struct console *co, const char *s,
249                                  unsigned int count)
250 {
251         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)) {
263                         if (ehv_bc_console_byte_channel_send(stdout_bc, s2, j))
264                                 return;
265                         j = 0;
266                 }
267         }
268 
269         if (j)
270                 ehv_bc_console_byte_channel_send(stdout_bc, s2, j);
271 }
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  */
278 static 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 
285 static 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  */
300 static 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 
316         /* 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 }
328 console_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  */
337 static irqreturn_t ehv_bc_tty_rx_isr(int irq, void *data)
338 {
339         struct ehv_bc_data *bc = data;
340         unsigned int rx_count, tx_count, len;
341         int count;
342         char buffer[EV_BYTE_CHANNEL_MAX_BYTES];
343         int ret;
344 
345         /* 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);
350         count = tty_buffer_request_room(&bc->port, rx_count);
351 
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. */
371                 ret = tty_insert_flip_string(&bc->port, buffer, len);
372 
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. */
386         tty_flip_buffer_push(&bc->port);
387 
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  */
397 static 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  */
438 static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
439 {
440         struct ehv_bc_data *bc = data;
441 
442         ehv_bc_tx_dequeue(bc);
443         tty_port_tty_wakeup(&bc->port);
444 
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  */
459 static 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  */
499 static 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  */
514 static 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  */
529 static 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  */
554 static 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  */
568 static 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 
578 static 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  */
593 static 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  */
610 static 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 
644 static 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 
652 static 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 
657 static int ehv_bc_tty_probe(struct platform_device *pdev)
658 {
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 
696         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);
701         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 
707         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 
714 error:
715         tty_port_destroy(&bc->port);
716         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 
723 static 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 
729         tty_port_destroy(&bc->port);
730         irq_dispose_mapping(bc->tx_irq);
731         irq_dispose_mapping(bc->rx_irq);
732 
733         return 0;
734 }
735 
736 static const struct of_device_id ehv_bc_tty_of_ids[] = {
737         { .compatible = "epapr,hv-byte-channel" },
738         {}
739 };
740 
741 static 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  */
756 static 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 
786         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 
809 error:
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  */
826 static void __exit ehv_bc_exit(void)
827 {
828         platform_driver_unregister(&ehv_bc_tty_driver);
829         tty_unregister_driver(ehv_bc_driver);
830         put_tty_driver(ehv_bc_driver);
831         kfree(bcs);
832 }
833 
834 module_init(ehv_bc_init);
835 module_exit(ehv_bc_exit);
836 
837 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
838 MODULE_DESCRIPTION("ePAPR hypervisor byte channel driver");
839 MODULE_LICENSE("GPL v2");
840 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us