James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 1 | /* |
| 2 | * dashtty.c - tty driver for Dash channels interface. |
| 3 | * |
| 4 | * Copyright (C) 2007,2008,2012 Imagination Technologies |
| 5 | * |
| 6 | * This file is subject to the terms and conditions of the GNU General Public |
| 7 | * License. See the file COPYING in the main directory of this archive |
| 8 | * for more details. |
| 9 | * |
| 10 | */ |
| 11 | |
| 12 | #include <linux/atomic.h> |
| 13 | #include <linux/completion.h> |
| 14 | #include <linux/console.h> |
| 15 | #include <linux/delay.h> |
| 16 | #include <linux/export.h> |
| 17 | #include <linux/init.h> |
| 18 | #include <linux/kernel.h> |
| 19 | #include <linux/kthread.h> |
James Hogan | c3f43ee | 2014-09-12 23:15:22 +0100 | [diff] [blame] | 20 | #include <linux/moduleparam.h> |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 21 | #include <linux/mutex.h> |
| 22 | #include <linux/sched.h> |
| 23 | #include <linux/serial.h> |
| 24 | #include <linux/slab.h> |
| 25 | #include <linux/spinlock.h> |
| 26 | #include <linux/string.h> |
| 27 | #include <linux/timer.h> |
| 28 | #include <linux/tty.h> |
| 29 | #include <linux/tty_driver.h> |
| 30 | #include <linux/tty_flip.h> |
| 31 | #include <linux/uaccess.h> |
| 32 | |
| 33 | #include <asm/da.h> |
| 34 | |
| 35 | /* Channel error codes */ |
| 36 | #define CONAOK 0 |
| 37 | #define CONERR 1 |
| 38 | #define CONBAD 2 |
| 39 | #define CONPRM 3 |
| 40 | #define CONADR 4 |
| 41 | #define CONCNT 5 |
| 42 | #define CONCBF 6 |
| 43 | #define CONCBE 7 |
| 44 | #define CONBSY 8 |
| 45 | |
| 46 | /* Default channel for the console */ |
| 47 | #define CONSOLE_CHANNEL 1 |
| 48 | |
| 49 | #define NUM_TTY_CHANNELS 6 |
| 50 | |
| 51 | /* Auto allocate */ |
| 52 | #define DA_TTY_MAJOR 0 |
| 53 | |
| 54 | /* A speedy poll rate helps the userland debug process connection response. |
| 55 | * But, if you set it too high then no other userland processes get much |
| 56 | * of a look in. |
| 57 | */ |
| 58 | #define DA_TTY_POLL (HZ / 50) |
| 59 | |
| 60 | /* |
| 61 | * A short put delay improves latency but has a high throughput overhead |
| 62 | */ |
| 63 | #define DA_TTY_PUT_DELAY (HZ / 100) |
| 64 | |
| 65 | static atomic_t num_channels_need_poll = ATOMIC_INIT(0); |
| 66 | |
| 67 | static struct timer_list poll_timer; |
| 68 | |
| 69 | static struct tty_driver *channel_driver; |
| 70 | |
| 71 | static struct timer_list put_timer; |
| 72 | static struct task_struct *dashtty_thread; |
| 73 | |
James Hogan | c3f43ee | 2014-09-12 23:15:22 +0100 | [diff] [blame] | 74 | /* |
| 75 | * The console_poll parameter determines whether the console channel should be |
| 76 | * polled for input. |
| 77 | * By default the console channel isn't polled at all, in order to avoid the |
| 78 | * overhead, but that means it isn't possible to have a login on /dev/console. |
| 79 | */ |
| 80 | static bool console_poll; |
| 81 | module_param(console_poll, bool, S_IRUGO); |
| 82 | |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 83 | #define RX_BUF_SIZE 1024 |
| 84 | |
| 85 | enum { |
| 86 | INCHR = 1, |
| 87 | OUTCHR, |
| 88 | RDBUF, |
| 89 | WRBUF, |
| 90 | RDSTAT |
| 91 | }; |
| 92 | |
| 93 | /** |
| 94 | * struct dashtty_port - Wrapper struct for dashtty tty_port. |
| 95 | * @port: TTY port data |
| 96 | * @rx_lock: Lock for rx_buf. |
| 97 | * This protects between the poll timer and user context. |
| 98 | * It's also held during read SWITCH operations. |
| 99 | * @rx_buf: Read buffer |
| 100 | * @xmit_lock: Lock for xmit_*, and port.xmit_buf. |
| 101 | * This protects between user context and kernel thread. |
| 102 | * It's also held during write SWITCH operations. |
| 103 | * @xmit_cnt: Size of xmit buffer contents |
| 104 | * @xmit_head: Head of xmit buffer where data is written |
| 105 | * @xmit_tail: Tail of xmit buffer where data is read |
| 106 | * @xmit_empty: Completion for xmit buffer being empty |
| 107 | */ |
| 108 | struct dashtty_port { |
| 109 | struct tty_port port; |
| 110 | spinlock_t rx_lock; |
| 111 | void *rx_buf; |
| 112 | struct mutex xmit_lock; |
| 113 | unsigned int xmit_cnt; |
| 114 | unsigned int xmit_head; |
| 115 | unsigned int xmit_tail; |
| 116 | struct completion xmit_empty; |
| 117 | }; |
| 118 | |
| 119 | static struct dashtty_port dashtty_ports[NUM_TTY_CHANNELS]; |
| 120 | |
| 121 | static atomic_t dashtty_xmit_cnt = ATOMIC_INIT(0); |
| 122 | static wait_queue_head_t dashtty_waitqueue; |
| 123 | |
| 124 | /* |
| 125 | * Low-level DA channel access routines |
| 126 | */ |
| 127 | static int chancall(int in_bios_function, int in_channel, |
| 128 | int in_arg2, void *in_arg3, |
| 129 | void *in_arg4) |
| 130 | { |
| 131 | register int bios_function asm("D1Ar1") = in_bios_function; |
| 132 | register int channel asm("D0Ar2") = in_channel; |
| 133 | register int arg2 asm("D1Ar3") = in_arg2; |
| 134 | register void *arg3 asm("D0Ar4") = in_arg3; |
| 135 | register void *arg4 asm("D1Ar5") = in_arg4; |
| 136 | register int bios_call asm("D0Ar6") = 3; |
| 137 | register int result asm("D0Re0"); |
| 138 | |
| 139 | asm volatile ( |
| 140 | "MSETL [A0StP++], %6,%4,%2\n\t" |
| 141 | "ADD A0StP, A0StP, #8\n\t" |
| 142 | "SWITCH #0x0C30208\n\t" |
| 143 | "GETD %0, [A0StP+#-8]\n\t" |
| 144 | "SUB A0StP, A0StP, #(4*6)+8\n\t" |
| 145 | : "=d" (result) /* outs */ |
| 146 | : "d" (bios_function), |
| 147 | "d" (channel), |
| 148 | "d" (arg2), |
| 149 | "d" (arg3), |
| 150 | "d" (arg4), |
| 151 | "d" (bios_call) /* ins */ |
| 152 | : "memory"); |
| 153 | |
| 154 | return result; |
| 155 | } |
| 156 | |
| 157 | /* |
| 158 | * Attempts to fetch count bytes from channel and returns actual count. |
| 159 | */ |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 160 | static int fetch_data(unsigned int channel) |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 161 | { |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 162 | struct dashtty_port *dport = &dashtty_ports[channel]; |
| 163 | int received = 0; |
| 164 | |
| 165 | spin_lock_bh(&dport->rx_lock); |
| 166 | /* check the port isn't being shut down */ |
| 167 | if (!dport->rx_buf) |
| 168 | goto unlock; |
| 169 | if (chancall(RDBUF, channel, RX_BUF_SIZE, |
| 170 | (void *)dport->rx_buf, &received) == CONAOK) { |
| 171 | if (received) { |
| 172 | int space; |
| 173 | unsigned char *cbuf; |
| 174 | |
| 175 | space = tty_prepare_flip_string(&dport->port, &cbuf, |
| 176 | received); |
| 177 | |
| 178 | if (space <= 0) |
| 179 | goto unlock; |
| 180 | |
| 181 | memcpy(cbuf, dport->rx_buf, space); |
| 182 | tty_flip_buffer_push(&dport->port); |
| 183 | } |
| 184 | } |
| 185 | unlock: |
| 186 | spin_unlock_bh(&dport->rx_lock); |
| 187 | |
| 188 | return received; |
| 189 | } |
| 190 | |
| 191 | /** |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 192 | * find_channel_to_poll() - Returns number of the next channel to poll. |
| 193 | * Returns: The number of the next channel to poll, or -1 if none need |
| 194 | * polling. |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 195 | */ |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 196 | static int find_channel_to_poll(void) |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 197 | { |
| 198 | static int last_polled_channel; |
| 199 | int last = last_polled_channel; |
| 200 | int chan; |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 201 | struct dashtty_port *dport; |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 202 | |
| 203 | for (chan = last + 1; ; ++chan) { |
| 204 | if (chan >= NUM_TTY_CHANNELS) |
| 205 | chan = 0; |
| 206 | |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 207 | dport = &dashtty_ports[chan]; |
| 208 | if (dport->rx_buf) { |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 209 | last_polled_channel = chan; |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 210 | return chan; |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 211 | } |
| 212 | |
| 213 | if (chan == last) |
| 214 | break; |
| 215 | } |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 216 | return -1; |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 217 | } |
| 218 | |
| 219 | /** |
| 220 | * put_channel_data() - Write out a block of channel data. |
| 221 | * @chan: DA channel number. |
| 222 | * |
| 223 | * Write a single block of data out to the debug adapter. If the circular buffer |
| 224 | * is wrapped then only the first block is written. |
| 225 | * |
| 226 | * Returns: 1 if the remote buffer was too full to accept data. |
| 227 | * 0 otherwise. |
| 228 | */ |
| 229 | static int put_channel_data(unsigned int chan) |
| 230 | { |
| 231 | struct dashtty_port *dport; |
| 232 | struct tty_struct *tty; |
| 233 | int number_written; |
| 234 | unsigned int count = 0; |
| 235 | |
| 236 | dport = &dashtty_ports[chan]; |
| 237 | mutex_lock(&dport->xmit_lock); |
| 238 | if (dport->xmit_cnt) { |
| 239 | count = min((unsigned int)(SERIAL_XMIT_SIZE - dport->xmit_tail), |
| 240 | dport->xmit_cnt); |
| 241 | chancall(WRBUF, chan, count, |
| 242 | dport->port.xmit_buf + dport->xmit_tail, |
| 243 | &number_written); |
| 244 | dport->xmit_cnt -= number_written; |
| 245 | if (!dport->xmit_cnt) { |
| 246 | /* reset pointers to avoid wraps */ |
| 247 | dport->xmit_head = 0; |
| 248 | dport->xmit_tail = 0; |
| 249 | complete(&dport->xmit_empty); |
| 250 | } else { |
| 251 | dport->xmit_tail += number_written; |
| 252 | if (dport->xmit_tail >= SERIAL_XMIT_SIZE) |
| 253 | dport->xmit_tail -= SERIAL_XMIT_SIZE; |
| 254 | } |
| 255 | atomic_sub(number_written, &dashtty_xmit_cnt); |
| 256 | } |
| 257 | mutex_unlock(&dport->xmit_lock); |
| 258 | |
| 259 | /* if we've made more data available, wake up tty */ |
| 260 | if (count && number_written) { |
| 261 | tty = tty_port_tty_get(&dport->port); |
| 262 | if (tty) { |
| 263 | tty_wakeup(tty); |
| 264 | tty_kref_put(tty); |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | /* did the write fail? */ |
| 269 | return count && !number_written; |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * put_data() - Kernel thread to write out blocks of channel data to DA. |
| 274 | * @arg: Unused. |
| 275 | * |
| 276 | * This kernel thread runs while @dashtty_xmit_cnt != 0, and loops over the |
| 277 | * channels to write out any buffered data. If any of the channels stall due to |
| 278 | * the remote buffer being full, a hold off happens to allow the debugger to |
| 279 | * drain the buffer. |
| 280 | */ |
| 281 | static int put_data(void *arg) |
| 282 | { |
| 283 | unsigned int chan, stall; |
| 284 | |
| 285 | __set_current_state(TASK_RUNNING); |
| 286 | while (!kthread_should_stop()) { |
| 287 | /* |
| 288 | * For each channel see if there's anything to transmit in the |
| 289 | * port's xmit_buf. |
| 290 | */ |
| 291 | stall = 0; |
| 292 | for (chan = 0; chan < NUM_TTY_CHANNELS; ++chan) |
| 293 | stall += put_channel_data(chan); |
| 294 | |
| 295 | /* |
| 296 | * If some of the buffers are full, hold off for a short while |
| 297 | * to allow them to empty. |
| 298 | */ |
| 299 | if (stall) |
| 300 | msleep(25); |
| 301 | |
| 302 | wait_event_interruptible(dashtty_waitqueue, |
| 303 | atomic_read(&dashtty_xmit_cnt)); |
| 304 | } |
| 305 | |
| 306 | return 0; |
| 307 | } |
| 308 | |
| 309 | /* |
| 310 | * This gets called every DA_TTY_POLL and polls the channels for data |
| 311 | */ |
| 312 | static void dashtty_timer(unsigned long ignored) |
| 313 | { |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 314 | int channel; |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 315 | |
| 316 | /* If there are no ports open do nothing and don't poll again. */ |
| 317 | if (!atomic_read(&num_channels_need_poll)) |
| 318 | return; |
| 319 | |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 320 | channel = find_channel_to_poll(); |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 321 | |
| 322 | /* Did we find a channel to poll? */ |
James Hogan | a8cd985 | 2013-02-06 14:45:02 +0000 | [diff] [blame] | 323 | if (channel >= 0) |
| 324 | fetch_data(channel); |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 325 | |
| 326 | mod_timer_pinned(&poll_timer, jiffies + DA_TTY_POLL); |
| 327 | } |
| 328 | |
| 329 | static void add_poll_timer(struct timer_list *poll_timer) |
| 330 | { |
| 331 | setup_timer(poll_timer, dashtty_timer, 0); |
| 332 | poll_timer->expires = jiffies + DA_TTY_POLL; |
| 333 | |
| 334 | /* |
| 335 | * Always attach the timer to the boot CPU. The DA channels are per-CPU |
| 336 | * so all polling should be from a single CPU. |
| 337 | */ |
| 338 | add_timer_on(poll_timer, 0); |
| 339 | } |
| 340 | |
| 341 | static int dashtty_port_activate(struct tty_port *port, struct tty_struct *tty) |
| 342 | { |
| 343 | struct dashtty_port *dport = container_of(port, struct dashtty_port, |
| 344 | port); |
| 345 | void *rx_buf; |
| 346 | |
| 347 | /* Allocate the buffer we use for writing data */ |
| 348 | if (tty_port_alloc_xmit_buf(port) < 0) |
| 349 | goto err; |
| 350 | |
| 351 | /* Allocate the buffer we use for reading data */ |
| 352 | rx_buf = kzalloc(RX_BUF_SIZE, GFP_KERNEL); |
| 353 | if (!rx_buf) |
| 354 | goto err_free_xmit; |
| 355 | |
| 356 | spin_lock_bh(&dport->rx_lock); |
| 357 | dport->rx_buf = rx_buf; |
| 358 | spin_unlock_bh(&dport->rx_lock); |
| 359 | |
| 360 | /* |
| 361 | * Don't add the poll timer if we're opening a console. This |
| 362 | * avoids the overhead of polling the Dash but means it is not |
| 363 | * possible to have a login on /dev/console. |
| 364 | * |
| 365 | */ |
James Hogan | c3f43ee | 2014-09-12 23:15:22 +0100 | [diff] [blame] | 366 | if (console_poll || dport != &dashtty_ports[CONSOLE_CHANNEL]) |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 367 | if (atomic_inc_return(&num_channels_need_poll) == 1) |
| 368 | add_poll_timer(&poll_timer); |
| 369 | |
| 370 | return 0; |
| 371 | err_free_xmit: |
| 372 | tty_port_free_xmit_buf(port); |
| 373 | err: |
| 374 | return -ENOMEM; |
| 375 | } |
| 376 | |
| 377 | static void dashtty_port_shutdown(struct tty_port *port) |
| 378 | { |
| 379 | struct dashtty_port *dport = container_of(port, struct dashtty_port, |
| 380 | port); |
| 381 | void *rx_buf; |
| 382 | unsigned int count; |
| 383 | |
| 384 | /* stop reading */ |
James Hogan | c3f43ee | 2014-09-12 23:15:22 +0100 | [diff] [blame] | 385 | if (console_poll || dport != &dashtty_ports[CONSOLE_CHANNEL]) |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 386 | if (atomic_dec_and_test(&num_channels_need_poll)) |
| 387 | del_timer_sync(&poll_timer); |
| 388 | |
| 389 | mutex_lock(&dport->xmit_lock); |
| 390 | count = dport->xmit_cnt; |
| 391 | mutex_unlock(&dport->xmit_lock); |
| 392 | if (count) { |
| 393 | /* |
| 394 | * There's still data to write out, so wake and wait for the |
| 395 | * writer thread to drain the buffer. |
| 396 | */ |
| 397 | del_timer(&put_timer); |
| 398 | wake_up_interruptible(&dashtty_waitqueue); |
| 399 | wait_for_completion(&dport->xmit_empty); |
| 400 | } |
| 401 | |
| 402 | /* Null the read buffer (timer could still be running!) */ |
| 403 | spin_lock_bh(&dport->rx_lock); |
| 404 | rx_buf = dport->rx_buf; |
| 405 | dport->rx_buf = NULL; |
| 406 | spin_unlock_bh(&dport->rx_lock); |
| 407 | /* Free the read buffer */ |
| 408 | kfree(rx_buf); |
| 409 | |
| 410 | /* Free the write buffer */ |
| 411 | tty_port_free_xmit_buf(port); |
| 412 | } |
| 413 | |
| 414 | static const struct tty_port_operations dashtty_port_ops = { |
| 415 | .activate = dashtty_port_activate, |
| 416 | .shutdown = dashtty_port_shutdown, |
| 417 | }; |
| 418 | |
| 419 | static int dashtty_install(struct tty_driver *driver, struct tty_struct *tty) |
| 420 | { |
| 421 | return tty_port_install(&dashtty_ports[tty->index].port, driver, tty); |
| 422 | } |
| 423 | |
| 424 | static int dashtty_open(struct tty_struct *tty, struct file *filp) |
| 425 | { |
| 426 | return tty_port_open(tty->port, tty, filp); |
| 427 | } |
| 428 | |
| 429 | static void dashtty_close(struct tty_struct *tty, struct file *filp) |
| 430 | { |
| 431 | return tty_port_close(tty->port, tty, filp); |
| 432 | } |
| 433 | |
| 434 | static void dashtty_hangup(struct tty_struct *tty) |
| 435 | { |
| 436 | int channel; |
| 437 | struct dashtty_port *dport; |
| 438 | |
| 439 | channel = tty->index; |
| 440 | dport = &dashtty_ports[channel]; |
| 441 | |
| 442 | /* drop any data in the xmit buffer */ |
| 443 | mutex_lock(&dport->xmit_lock); |
| 444 | if (dport->xmit_cnt) { |
| 445 | atomic_sub(dport->xmit_cnt, &dashtty_xmit_cnt); |
| 446 | dport->xmit_cnt = 0; |
| 447 | dport->xmit_head = 0; |
| 448 | dport->xmit_tail = 0; |
| 449 | complete(&dport->xmit_empty); |
| 450 | } |
| 451 | mutex_unlock(&dport->xmit_lock); |
| 452 | |
| 453 | tty_port_hangup(tty->port); |
| 454 | } |
| 455 | |
| 456 | /** |
| 457 | * dashtty_put_timer() - Delayed wake up of kernel thread. |
| 458 | * @ignored: unused |
| 459 | * |
| 460 | * This timer function wakes up the kernel thread if any data exists in the |
| 461 | * buffers. It is used to delay the expensive writeout until the writer has |
| 462 | * stopped writing. |
| 463 | */ |
| 464 | static void dashtty_put_timer(unsigned long ignored) |
| 465 | { |
| 466 | if (atomic_read(&dashtty_xmit_cnt)) |
| 467 | wake_up_interruptible(&dashtty_waitqueue); |
| 468 | } |
| 469 | |
| 470 | static int dashtty_write(struct tty_struct *tty, const unsigned char *buf, |
| 471 | int total) |
| 472 | { |
| 473 | int channel, count, block; |
| 474 | struct dashtty_port *dport; |
| 475 | |
| 476 | /* Determine the channel */ |
| 477 | channel = tty->index; |
| 478 | dport = &dashtty_ports[channel]; |
| 479 | |
| 480 | /* |
| 481 | * Write to output buffer. |
| 482 | * |
| 483 | * The reason that we asynchronously write the buffer is because if we |
| 484 | * were to write the buffer synchronously then because DA channels are |
| 485 | * per-CPU the buffer would be written to the channel of whatever CPU |
| 486 | * we're running on. |
| 487 | * |
| 488 | * What we actually want to happen is have all input and output done on |
| 489 | * one CPU. |
| 490 | */ |
| 491 | mutex_lock(&dport->xmit_lock); |
| 492 | /* work out how many bytes we can write to the xmit buffer */ |
| 493 | total = min(total, (int)(SERIAL_XMIT_SIZE - dport->xmit_cnt)); |
| 494 | atomic_add(total, &dashtty_xmit_cnt); |
| 495 | dport->xmit_cnt += total; |
| 496 | /* write the actual bytes (may need splitting if it wraps) */ |
| 497 | for (count = total; count; count -= block) { |
| 498 | block = min(count, (int)(SERIAL_XMIT_SIZE - dport->xmit_head)); |
| 499 | memcpy(dport->port.xmit_buf + dport->xmit_head, buf, block); |
| 500 | dport->xmit_head += block; |
| 501 | if (dport->xmit_head >= SERIAL_XMIT_SIZE) |
| 502 | dport->xmit_head -= SERIAL_XMIT_SIZE; |
| 503 | buf += block; |
| 504 | } |
| 505 | count = dport->xmit_cnt; |
| 506 | /* xmit buffer no longer empty? */ |
| 507 | if (count) |
Wolfram Sang | 16735d0 | 2013-11-14 14:32:02 -0800 | [diff] [blame] | 508 | reinit_completion(&dport->xmit_empty); |
James Hogan | 8200e38 | 2013-02-06 14:45:01 +0000 | [diff] [blame] | 509 | mutex_unlock(&dport->xmit_lock); |
| 510 | |
| 511 | if (total) { |
| 512 | /* |
| 513 | * If the buffer is full, wake up the kthread, otherwise allow |
| 514 | * some more time for the buffer to fill up a bit before waking |
| 515 | * it. |
| 516 | */ |
| 517 | if (count == SERIAL_XMIT_SIZE) { |
| 518 | del_timer(&put_timer); |
| 519 | wake_up_interruptible(&dashtty_waitqueue); |
| 520 | } else { |
| 521 | mod_timer(&put_timer, jiffies + DA_TTY_PUT_DELAY); |
| 522 | } |
| 523 | } |
| 524 | return total; |
| 525 | } |
| 526 | |
| 527 | static int dashtty_write_room(struct tty_struct *tty) |
| 528 | { |
| 529 | struct dashtty_port *dport; |
| 530 | int channel; |
| 531 | int room; |
| 532 | |
| 533 | channel = tty->index; |
| 534 | dport = &dashtty_ports[channel]; |
| 535 | |
| 536 | /* report the space in the xmit buffer */ |
| 537 | mutex_lock(&dport->xmit_lock); |
| 538 | room = SERIAL_XMIT_SIZE - dport->xmit_cnt; |
| 539 | mutex_unlock(&dport->xmit_lock); |
| 540 | |
| 541 | return room; |
| 542 | } |
| 543 | |
| 544 | static int dashtty_chars_in_buffer(struct tty_struct *tty) |
| 545 | { |
| 546 | struct dashtty_port *dport; |
| 547 | int channel; |
| 548 | int chars; |
| 549 | |
| 550 | channel = tty->index; |
| 551 | dport = &dashtty_ports[channel]; |
| 552 | |
| 553 | /* report the number of bytes in the xmit buffer */ |
| 554 | mutex_lock(&dport->xmit_lock); |
| 555 | chars = dport->xmit_cnt; |
| 556 | mutex_unlock(&dport->xmit_lock); |
| 557 | |
| 558 | return chars; |
| 559 | } |
| 560 | |
| 561 | static const struct tty_operations dashtty_ops = { |
| 562 | .install = dashtty_install, |
| 563 | .open = dashtty_open, |
| 564 | .close = dashtty_close, |
| 565 | .hangup = dashtty_hangup, |
| 566 | .write = dashtty_write, |
| 567 | .write_room = dashtty_write_room, |
| 568 | .chars_in_buffer = dashtty_chars_in_buffer, |
| 569 | }; |
| 570 | |
| 571 | static int __init dashtty_init(void) |
| 572 | { |
| 573 | int ret; |
| 574 | int nport; |
| 575 | struct dashtty_port *dport; |
| 576 | |
| 577 | if (!metag_da_enabled()) |
| 578 | return -ENODEV; |
| 579 | |
| 580 | channel_driver = tty_alloc_driver(NUM_TTY_CHANNELS, |
| 581 | TTY_DRIVER_REAL_RAW); |
| 582 | if (IS_ERR(channel_driver)) |
| 583 | return PTR_ERR(channel_driver); |
| 584 | |
| 585 | channel_driver->driver_name = "metag_da"; |
| 586 | channel_driver->name = "ttyDA"; |
| 587 | channel_driver->major = DA_TTY_MAJOR; |
| 588 | channel_driver->minor_start = 0; |
| 589 | channel_driver->type = TTY_DRIVER_TYPE_SERIAL; |
| 590 | channel_driver->subtype = SERIAL_TYPE_NORMAL; |
| 591 | channel_driver->init_termios = tty_std_termios; |
| 592 | channel_driver->init_termios.c_cflag |= CLOCAL; |
| 593 | |
| 594 | tty_set_operations(channel_driver, &dashtty_ops); |
| 595 | for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { |
| 596 | dport = &dashtty_ports[nport]; |
| 597 | tty_port_init(&dport->port); |
| 598 | dport->port.ops = &dashtty_port_ops; |
| 599 | spin_lock_init(&dport->rx_lock); |
| 600 | mutex_init(&dport->xmit_lock); |
| 601 | /* the xmit buffer starts empty, i.e. completely written */ |
| 602 | init_completion(&dport->xmit_empty); |
| 603 | complete(&dport->xmit_empty); |
| 604 | } |
| 605 | |
| 606 | setup_timer(&put_timer, dashtty_put_timer, 0); |
| 607 | |
| 608 | init_waitqueue_head(&dashtty_waitqueue); |
| 609 | dashtty_thread = kthread_create(put_data, NULL, "ttyDA"); |
| 610 | if (IS_ERR(dashtty_thread)) { |
| 611 | pr_err("Couldn't create dashtty thread\n"); |
| 612 | ret = PTR_ERR(dashtty_thread); |
| 613 | goto err_destroy_ports; |
| 614 | } |
| 615 | /* |
| 616 | * Bind the writer thread to the boot CPU so it can't migrate. |
| 617 | * DA channels are per-CPU and we want all channel I/O to be on a single |
| 618 | * predictable CPU. |
| 619 | */ |
| 620 | kthread_bind(dashtty_thread, 0); |
| 621 | wake_up_process(dashtty_thread); |
| 622 | |
| 623 | ret = tty_register_driver(channel_driver); |
| 624 | |
| 625 | if (ret < 0) { |
| 626 | pr_err("Couldn't install dashtty driver: err %d\n", |
| 627 | ret); |
| 628 | goto err_stop_kthread; |
| 629 | } |
| 630 | |
| 631 | return 0; |
| 632 | |
| 633 | err_stop_kthread: |
| 634 | kthread_stop(dashtty_thread); |
| 635 | err_destroy_ports: |
| 636 | for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { |
| 637 | dport = &dashtty_ports[nport]; |
| 638 | tty_port_destroy(&dport->port); |
| 639 | } |
| 640 | put_tty_driver(channel_driver); |
| 641 | return ret; |
| 642 | } |
| 643 | |
| 644 | static void dashtty_exit(void) |
| 645 | { |
| 646 | int nport; |
| 647 | struct dashtty_port *dport; |
| 648 | |
| 649 | del_timer_sync(&put_timer); |
| 650 | kthread_stop(dashtty_thread); |
| 651 | del_timer_sync(&poll_timer); |
| 652 | tty_unregister_driver(channel_driver); |
| 653 | for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { |
| 654 | dport = &dashtty_ports[nport]; |
| 655 | tty_port_destroy(&dport->port); |
| 656 | } |
| 657 | put_tty_driver(channel_driver); |
| 658 | } |
| 659 | |
| 660 | module_init(dashtty_init); |
| 661 | module_exit(dashtty_exit); |
| 662 | |
| 663 | #ifdef CONFIG_DA_CONSOLE |
| 664 | |
| 665 | static void dash_console_write(struct console *co, const char *s, |
| 666 | unsigned int count) |
| 667 | { |
| 668 | int actually_written; |
| 669 | |
| 670 | chancall(WRBUF, CONSOLE_CHANNEL, count, (void *)s, &actually_written); |
| 671 | } |
| 672 | |
| 673 | static struct tty_driver *dash_console_device(struct console *c, int *index) |
| 674 | { |
| 675 | *index = c->index; |
| 676 | return channel_driver; |
| 677 | } |
| 678 | |
| 679 | struct console dash_console = { |
| 680 | .name = "ttyDA", |
| 681 | .write = dash_console_write, |
| 682 | .device = dash_console_device, |
| 683 | .flags = CON_PRINTBUFFER, |
| 684 | .index = 1, |
| 685 | }; |
| 686 | |
| 687 | #endif |