1 /************************************************************************
2 * Copyright 2003 Digi International (www.digi.com)
4 * Copyright (C) 2004 IBM Corporation. All rights reserved.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2, or (at your option)
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
13 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
14 * PURPOSE. See the GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 * Temple Place - Suite 330, Boston,
21 * Contact Information:
22 * Scott H Kilau <Scott_Kilau@digi.com>
23 * Ananda Venkatarman <mansarov@us.ibm.com>
25 * 01/19/06: changed jsm_input routine to use the dynamically allocated
26 * tty_buffer changes. Contributors: Scott Kilau and Ananda V.
27 ***********************************************************************/
28 #include <linux/tty.h>
29 #include <linux/tty_flip.h>
30 #include <linux/serial_reg.h>
31 #include <linux/delay.h> /* For udelay */
32 #include <linux/pci.h>
33 #include <linux/slab.h>
37 static DECLARE_BITMAP(linemap
, MAXLINES
);
39 static void jsm_carrier(struct jsm_channel
*ch
);
41 static inline int jsm_get_mstat(struct jsm_channel
*ch
)
46 jsm_dbg(IOCTL
, &ch
->ch_bd
->pci_dev
, "start\n");
48 mstat
= (ch
->ch_mostat
| ch
->ch_mistat
);
52 if (mstat
& UART_MCR_DTR
)
54 if (mstat
& UART_MCR_RTS
)
56 if (mstat
& UART_MSR_CTS
)
58 if (mstat
& UART_MSR_DSR
)
60 if (mstat
& UART_MSR_RI
)
62 if (mstat
& UART_MSR_DCD
)
65 jsm_dbg(IOCTL
, &ch
->ch_bd
->pci_dev
, "finish\n");
69 static unsigned int jsm_tty_tx_empty(struct uart_port
*port
)
75 * Return modem signals to ld.
77 static unsigned int jsm_tty_get_mctrl(struct uart_port
*port
)
80 struct jsm_channel
*channel
=
81 container_of(port
, struct jsm_channel
, uart_port
);
83 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "start\n");
85 result
= jsm_get_mstat(channel
);
90 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "finish\n");
96 * jsm_set_modem_info()
98 * Set modem signals, called by ld.
100 static void jsm_tty_set_mctrl(struct uart_port
*port
, unsigned int mctrl
)
102 struct jsm_channel
*channel
=
103 container_of(port
, struct jsm_channel
, uart_port
);
105 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "start\n");
107 if (mctrl
& TIOCM_RTS
)
108 channel
->ch_mostat
|= UART_MCR_RTS
;
110 channel
->ch_mostat
&= ~UART_MCR_RTS
;
112 if (mctrl
& TIOCM_DTR
)
113 channel
->ch_mostat
|= UART_MCR_DTR
;
115 channel
->ch_mostat
&= ~UART_MCR_DTR
;
117 channel
->ch_bd
->bd_ops
->assert_modem_signals(channel
);
119 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "finish\n");
126 * Take data from the user or kernel and send it out to the FEP.
127 * In here exists all the Transparent Print magic as well.
129 static void jsm_tty_write(struct uart_port
*port
)
131 struct jsm_channel
*channel
;
132 channel
= container_of(port
, struct jsm_channel
, uart_port
);
133 channel
->ch_bd
->bd_ops
->copy_data_from_queue_to_uart(channel
);
136 static void jsm_tty_start_tx(struct uart_port
*port
)
138 struct jsm_channel
*channel
=
139 container_of(port
, struct jsm_channel
, uart_port
);
141 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "start\n");
143 channel
->ch_flags
&= ~(CH_STOP
);
146 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "finish\n");
149 static void jsm_tty_stop_tx(struct uart_port
*port
)
151 struct jsm_channel
*channel
=
152 container_of(port
, struct jsm_channel
, uart_port
);
154 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "start\n");
156 channel
->ch_flags
|= (CH_STOP
);
158 jsm_dbg(IOCTL
, &channel
->ch_bd
->pci_dev
, "finish\n");
161 static void jsm_tty_send_xchar(struct uart_port
*port
, char ch
)
163 unsigned long lock_flags
;
164 struct jsm_channel
*channel
=
165 container_of(port
, struct jsm_channel
, uart_port
);
166 struct ktermios
*termios
;
168 spin_lock_irqsave(&port
->lock
, lock_flags
);
169 termios
= &port
->state
->port
.tty
->termios
;
170 if (ch
== termios
->c_cc
[VSTART
])
171 channel
->ch_bd
->bd_ops
->send_start_character(channel
);
173 if (ch
== termios
->c_cc
[VSTOP
])
174 channel
->ch_bd
->bd_ops
->send_stop_character(channel
);
175 spin_unlock_irqrestore(&port
->lock
, lock_flags
);
178 static void jsm_tty_stop_rx(struct uart_port
*port
)
180 struct jsm_channel
*channel
=
181 container_of(port
, struct jsm_channel
, uart_port
);
183 channel
->ch_bd
->bd_ops
->disable_receiver(channel
);
186 static void jsm_tty_break(struct uart_port
*port
, int break_state
)
188 unsigned long lock_flags
;
189 struct jsm_channel
*channel
=
190 container_of(port
, struct jsm_channel
, uart_port
);
192 spin_lock_irqsave(&port
->lock
, lock_flags
);
193 if (break_state
== -1)
194 channel
->ch_bd
->bd_ops
->send_break(channel
);
196 channel
->ch_bd
->bd_ops
->clear_break(channel
, 0);
198 spin_unlock_irqrestore(&port
->lock
, lock_flags
);
201 static int jsm_tty_open(struct uart_port
*port
)
203 struct jsm_board
*brd
;
204 struct jsm_channel
*channel
=
205 container_of(port
, struct jsm_channel
, uart_port
);
206 struct ktermios
*termios
;
208 /* Get board pointer from our array of majors we have allocated */
209 brd
= channel
->ch_bd
;
212 * Allocate channel buffers for read/write/error.
213 * Set flag, so we don't get trounced on.
215 channel
->ch_flags
|= (CH_OPENING
);
217 /* Drop locks, as malloc with GFP_KERNEL can sleep */
219 if (!channel
->ch_rqueue
) {
220 channel
->ch_rqueue
= kzalloc(RQUEUESIZE
, GFP_KERNEL
);
221 if (!channel
->ch_rqueue
) {
222 jsm_dbg(INIT
, &channel
->ch_bd
->pci_dev
,
223 "unable to allocate read queue buf\n");
227 if (!channel
->ch_equeue
) {
228 channel
->ch_equeue
= kzalloc(EQUEUESIZE
, GFP_KERNEL
);
229 if (!channel
->ch_equeue
) {
230 jsm_dbg(INIT
, &channel
->ch_bd
->pci_dev
,
231 "unable to allocate error queue buf\n");
236 channel
->ch_flags
&= ~(CH_OPENING
);
238 * Initialize if neither terminal is open.
240 jsm_dbg(OPEN
, &channel
->ch_bd
->pci_dev
,
241 "jsm_open: initializing channel in open...\n");
244 * Flush input queues.
246 channel
->ch_r_head
= channel
->ch_r_tail
= 0;
247 channel
->ch_e_head
= channel
->ch_e_tail
= 0;
249 brd
->bd_ops
->flush_uart_write(channel
);
250 brd
->bd_ops
->flush_uart_read(channel
);
252 channel
->ch_flags
= 0;
253 channel
->ch_cached_lsr
= 0;
254 channel
->ch_stops_sent
= 0;
256 termios
= &port
->state
->port
.tty
->termios
;
257 channel
->ch_c_cflag
= termios
->c_cflag
;
258 channel
->ch_c_iflag
= termios
->c_iflag
;
259 channel
->ch_c_oflag
= termios
->c_oflag
;
260 channel
->ch_c_lflag
= termios
->c_lflag
;
261 channel
->ch_startc
= termios
->c_cc
[VSTART
];
262 channel
->ch_stopc
= termios
->c_cc
[VSTOP
];
264 /* Tell UART to init itself */
265 brd
->bd_ops
->uart_init(channel
);
268 * Run param in case we changed anything
270 brd
->bd_ops
->param(channel
);
272 jsm_carrier(channel
);
274 channel
->ch_open_count
++;
276 jsm_dbg(OPEN
, &channel
->ch_bd
->pci_dev
, "finish\n");
280 static void jsm_tty_close(struct uart_port
*port
)
282 struct jsm_board
*bd
;
284 struct jsm_channel
*channel
=
285 container_of(port
, struct jsm_channel
, uart_port
);
287 jsm_dbg(CLOSE
, &channel
->ch_bd
->pci_dev
, "start\n");
290 ts
= &port
->state
->port
.tty
->termios
;
292 channel
->ch_flags
&= ~(CH_STOPI
);
294 channel
->ch_open_count
--;
297 * If we have HUPCL set, lower DTR and RTS
299 if (channel
->ch_c_cflag
& HUPCL
) {
300 jsm_dbg(CLOSE
, &channel
->ch_bd
->pci_dev
,
301 "Close. HUPCL set, dropping DTR/RTS\n");
304 channel
->ch_mostat
&= ~(UART_MCR_DTR
| UART_MCR_RTS
);
305 bd
->bd_ops
->assert_modem_signals(channel
);
308 /* Turn off UART interrupts for this port */
309 channel
->ch_bd
->bd_ops
->uart_off(channel
);
311 jsm_dbg(CLOSE
, &channel
->ch_bd
->pci_dev
, "finish\n");
314 static void jsm_tty_set_termios(struct uart_port
*port
,
315 struct ktermios
*termios
,
316 struct ktermios
*old_termios
)
318 unsigned long lock_flags
;
319 struct jsm_channel
*channel
=
320 container_of(port
, struct jsm_channel
, uart_port
);
322 spin_lock_irqsave(&port
->lock
, lock_flags
);
323 channel
->ch_c_cflag
= termios
->c_cflag
;
324 channel
->ch_c_iflag
= termios
->c_iflag
;
325 channel
->ch_c_oflag
= termios
->c_oflag
;
326 channel
->ch_c_lflag
= termios
->c_lflag
;
327 channel
->ch_startc
= termios
->c_cc
[VSTART
];
328 channel
->ch_stopc
= termios
->c_cc
[VSTOP
];
330 channel
->ch_bd
->bd_ops
->param(channel
);
331 jsm_carrier(channel
);
332 spin_unlock_irqrestore(&port
->lock
, lock_flags
);
335 static const char *jsm_tty_type(struct uart_port
*port
)
340 static void jsm_tty_release_port(struct uart_port
*port
)
344 static int jsm_tty_request_port(struct uart_port
*port
)
349 static void jsm_config_port(struct uart_port
*port
, int flags
)
351 port
->type
= PORT_JSM
;
354 static struct uart_ops jsm_ops
= {
355 .tx_empty
= jsm_tty_tx_empty
,
356 .set_mctrl
= jsm_tty_set_mctrl
,
357 .get_mctrl
= jsm_tty_get_mctrl
,
358 .stop_tx
= jsm_tty_stop_tx
,
359 .start_tx
= jsm_tty_start_tx
,
360 .send_xchar
= jsm_tty_send_xchar
,
361 .stop_rx
= jsm_tty_stop_rx
,
362 .break_ctl
= jsm_tty_break
,
363 .startup
= jsm_tty_open
,
364 .shutdown
= jsm_tty_close
,
365 .set_termios
= jsm_tty_set_termios
,
366 .type
= jsm_tty_type
,
367 .release_port
= jsm_tty_release_port
,
368 .request_port
= jsm_tty_request_port
,
369 .config_port
= jsm_config_port
,
375 * Init the tty subsystem. Called once per board after board has been
376 * downloaded and init'ed.
378 int jsm_tty_init(struct jsm_board
*brd
)
382 struct jsm_channel
*ch
;
387 jsm_dbg(INIT
, &brd
->pci_dev
, "start\n");
390 * Initialize board structure elements.
393 brd
->nasync
= brd
->maxports
;
396 * Allocate channel memory that might not have been allocated
397 * when the driver was first loaded.
399 for (i
= 0; i
< brd
->nasync
; i
++) {
400 if (!brd
->channels
[i
]) {
403 * Okay to malloc with GFP_KERNEL, we are not at
404 * interrupt context, and there are no locks held.
406 brd
->channels
[i
] = kzalloc(sizeof(struct jsm_channel
), GFP_KERNEL
);
407 if (!brd
->channels
[i
]) {
408 jsm_dbg(CORE
, &brd
->pci_dev
,
409 "%s:%d Unable to allocate memory for channel struct\n",
415 ch
= brd
->channels
[0];
416 vaddr
= brd
->re_map_membase
;
418 /* Set up channel variables */
419 for (i
= 0; i
< brd
->nasync
; i
++, ch
= brd
->channels
[i
]) {
421 if (!brd
->channels
[i
])
424 spin_lock_init(&ch
->ch_lock
);
426 if (brd
->bd_uart_offset
== 0x200)
427 ch
->ch_neo_uart
= vaddr
+ (brd
->bd_uart_offset
* i
);
432 /* .25 second delay */
433 ch
->ch_close_delay
= 250;
435 init_waitqueue_head(&ch
->ch_flags_wait
);
438 jsm_dbg(INIT
, &brd
->pci_dev
, "finish\n");
442 int jsm_uart_port_init(struct jsm_board
*brd
)
446 struct jsm_channel
*ch
;
451 jsm_dbg(INIT
, &brd
->pci_dev
, "start\n");
454 * Initialize board structure elements.
457 brd
->nasync
= brd
->maxports
;
459 /* Set up channel variables */
460 for (i
= 0; i
< brd
->nasync
; i
++, ch
= brd
->channels
[i
]) {
462 if (!brd
->channels
[i
])
465 brd
->channels
[i
]->uart_port
.irq
= brd
->irq
;
466 brd
->channels
[i
]->uart_port
.uartclk
= 14745600;
467 brd
->channels
[i
]->uart_port
.type
= PORT_JSM
;
468 brd
->channels
[i
]->uart_port
.iotype
= UPIO_MEM
;
469 brd
->channels
[i
]->uart_port
.membase
= brd
->re_map_membase
;
470 brd
->channels
[i
]->uart_port
.fifosize
= 16;
471 brd
->channels
[i
]->uart_port
.ops
= &jsm_ops
;
472 line
= find_first_zero_bit(linemap
, MAXLINES
);
473 if (line
>= MAXLINES
) {
474 printk(KERN_INFO
"jsm: linemap is full, added device failed\n");
477 set_bit(line
, linemap
);
478 brd
->channels
[i
]->uart_port
.line
= line
;
479 rc
= uart_add_one_port (&jsm_uart_driver
, &brd
->channels
[i
]->uart_port
);
481 printk(KERN_INFO
"jsm: Port %d failed. Aborting...\n", i
);
485 printk(KERN_INFO
"jsm: Port %d added\n", i
);
488 jsm_dbg(INIT
, &brd
->pci_dev
, "finish\n");
492 int jsm_remove_uart_port(struct jsm_board
*brd
)
495 struct jsm_channel
*ch
;
500 jsm_dbg(INIT
, &brd
->pci_dev
, "start\n");
503 * Initialize board structure elements.
506 brd
->nasync
= brd
->maxports
;
508 /* Set up channel variables */
509 for (i
= 0; i
< brd
->nasync
; i
++) {
511 if (!brd
->channels
[i
])
514 ch
= brd
->channels
[i
];
516 clear_bit(ch
->uart_port
.line
, linemap
);
517 uart_remove_one_port(&jsm_uart_driver
, &brd
->channels
[i
]->uart_port
);
520 jsm_dbg(INIT
, &brd
->pci_dev
, "finish\n");
524 void jsm_input(struct jsm_channel
*ch
)
526 struct jsm_board
*bd
;
527 struct tty_struct
*tp
;
528 struct tty_port
*port
;
533 unsigned long lock_flags
;
539 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
, "start\n");
544 port
= &ch
->uart_port
.state
->port
;
551 spin_lock_irqsave(&ch
->ch_lock
, lock_flags
);
554 *Figure the number of characters in the buffer.
555 *Exit immediately if none.
560 head
= ch
->ch_r_head
& rmask
;
561 tail
= ch
->ch_r_tail
& rmask
;
563 data_len
= (head
- tail
) & rmask
;
565 spin_unlock_irqrestore(&ch
->ch_lock
, lock_flags
);
569 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
, "start\n");
572 *If the device is not open, or CREAD is off, flush
573 *input data and return immediately.
576 !(tp
->termios
.c_cflag
& CREAD
) ) {
578 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
579 "input. dropping %d bytes on port %d...\n",
580 data_len
, ch
->ch_portnum
);
581 ch
->ch_r_head
= tail
;
583 /* Force queue flow control to be released, if needed */
584 jsm_check_queue_flow_control(ch
);
586 spin_unlock_irqrestore(&ch
->ch_lock
, lock_flags
);
591 * If we are throttled, simply don't read any data.
593 if (ch
->ch_flags
& CH_STOPI
) {
594 spin_unlock_irqrestore(&ch
->ch_lock
, lock_flags
);
595 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
596 "Port %d throttled, not reading any data. head: %x tail: %x\n",
597 ch
->ch_portnum
, head
, tail
);
601 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
, "start 2\n");
603 len
= tty_buffer_request_room(port
, data_len
);
607 * n now contains the most amount of data we can copy,
608 * bounded either by the flip buffer size or the amount
609 * of data the card actually has pending...
612 s
= ((head
>= tail
) ? head
: RQUEUESIZE
) - tail
;
619 * If conditions are such that ld needs to see all
620 * UART errors, we will have to walk each character
621 * and error byte and send them to the buffer one at
625 if (I_PARMRK(tp
) || I_BRKINT(tp
) || I_INPCK(tp
)) {
626 for (i
= 0; i
< s
; i
++) {
628 * Give the Linux ld the flags in the
631 if (*(ch
->ch_equeue
+tail
+i
) & UART_LSR_BI
)
632 tty_insert_flip_char(port
, *(ch
->ch_rqueue
+tail
+i
), TTY_BREAK
);
633 else if (*(ch
->ch_equeue
+tail
+i
) & UART_LSR_PE
)
634 tty_insert_flip_char(port
, *(ch
->ch_rqueue
+tail
+i
), TTY_PARITY
);
635 else if (*(ch
->ch_equeue
+tail
+i
) & UART_LSR_FE
)
636 tty_insert_flip_char(port
, *(ch
->ch_rqueue
+tail
+i
), TTY_FRAME
);
638 tty_insert_flip_char(port
, *(ch
->ch_rqueue
+tail
+i
), TTY_NORMAL
);
641 tty_insert_flip_string(port
, ch
->ch_rqueue
+ tail
, s
);
645 /* Flip queue if needed */
649 ch
->ch_r_tail
= tail
& rmask
;
650 ch
->ch_e_tail
= tail
& rmask
;
651 jsm_check_queue_flow_control(ch
);
652 spin_unlock_irqrestore(&ch
->ch_lock
, lock_flags
);
654 /* Tell the tty layer its okay to "eat" the data now */
655 tty_flip_buffer_push(port
);
657 jsm_dbg(IOCTL
, &ch
->ch_bd
->pci_dev
, "finish\n");
660 static void jsm_carrier(struct jsm_channel
*ch
)
662 struct jsm_board
*bd
;
664 int virt_carrier
= 0;
665 int phys_carrier
= 0;
667 jsm_dbg(CARR
, &ch
->ch_bd
->pci_dev
, "start\n");
676 if (ch
->ch_mistat
& UART_MSR_DCD
) {
677 jsm_dbg(CARR
, &ch
->ch_bd
->pci_dev
, "mistat: %x D_CD: %x\n",
678 ch
->ch_mistat
, ch
->ch_mistat
& UART_MSR_DCD
);
682 if (ch
->ch_c_cflag
& CLOCAL
)
685 jsm_dbg(CARR
, &ch
->ch_bd
->pci_dev
, "DCD: physical: %d virt: %d\n",
686 phys_carrier
, virt_carrier
);
689 * Test for a VIRTUAL carrier transition to HIGH.
691 if (((ch
->ch_flags
& CH_FCAR
) == 0) && (virt_carrier
== 1)) {
694 * When carrier rises, wake any threads waiting
695 * for carrier in the open routine.
698 jsm_dbg(CARR
, &ch
->ch_bd
->pci_dev
, "carrier: virt DCD rose\n");
700 if (waitqueue_active(&(ch
->ch_flags_wait
)))
701 wake_up_interruptible(&ch
->ch_flags_wait
);
705 * Test for a PHYSICAL carrier transition to HIGH.
707 if (((ch
->ch_flags
& CH_CD
) == 0) && (phys_carrier
== 1)) {
710 * When carrier rises, wake any threads waiting
711 * for carrier in the open routine.
714 jsm_dbg(CARR
, &ch
->ch_bd
->pci_dev
,
715 "carrier: physical DCD rose\n");
717 if (waitqueue_active(&(ch
->ch_flags_wait
)))
718 wake_up_interruptible(&ch
->ch_flags_wait
);
722 * Test for a PHYSICAL transition to low, so long as we aren't
723 * currently ignoring physical transitions (which is what "virtual
724 * carrier" indicates).
726 * The transition of the virtual carrier to low really doesn't
727 * matter... it really only means "ignore carrier state", not
728 * "make pretend that carrier is there".
730 if ((virt_carrier
== 0) && ((ch
->ch_flags
& CH_CD
) != 0)
731 && (phys_carrier
== 0)) {
733 * When carrier drops:
735 * Drop carrier on all open units.
737 * Flush queues, waking up any task waiting in the
740 * Send a hangup to the control terminal.
742 * Enable all select calls.
744 if (waitqueue_active(&(ch
->ch_flags_wait
)))
745 wake_up_interruptible(&ch
->ch_flags_wait
);
749 * Make sure that our cached values reflect the current reality.
751 if (virt_carrier
== 1)
752 ch
->ch_flags
|= CH_FCAR
;
754 ch
->ch_flags
&= ~CH_FCAR
;
756 if (phys_carrier
== 1)
757 ch
->ch_flags
|= CH_CD
;
759 ch
->ch_flags
&= ~CH_CD
;
763 void jsm_check_queue_flow_control(struct jsm_channel
*ch
)
765 struct board_ops
*bd_ops
= ch
->ch_bd
->bd_ops
;
768 /* Store how much space we have left in the queue */
769 if ((qleft
= ch
->ch_r_tail
- ch
->ch_r_head
- 1) < 0)
770 qleft
+= RQUEUEMASK
+ 1;
773 * Check to see if we should enforce flow control on our queue because
774 * the ld (or user) isn't reading data out of our queue fast enuf.
776 * NOTE: This is done based on what the current flow control of the
779 * 1) HWFLOW (RTS) - Turn off the UART's Receive interrupt.
780 * This will cause the UART's FIFO to back up, and force
781 * the RTS signal to be dropped.
782 * 2) SWFLOW (IXOFF) - Keep trying to send a stop character to
783 * the other side, in hopes it will stop sending data to us.
784 * 3) NONE - Nothing we can do. We will simply drop any extra data
785 * that gets sent into us when the queue fills up.
789 if (ch
->ch_c_cflag
& CRTSCTS
) {
790 if(!(ch
->ch_flags
& CH_RECEIVER_OFF
)) {
791 bd_ops
->disable_receiver(ch
);
792 ch
->ch_flags
|= (CH_RECEIVER_OFF
);
793 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
794 "Internal queue hit hilevel mark (%d)! Turning off interrupts\n",
799 else if (ch
->ch_c_iflag
& IXOFF
) {
800 if (ch
->ch_stops_sent
<= MAX_STOPS_SENT
) {
801 bd_ops
->send_stop_character(ch
);
803 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
804 "Sending stop char! Times sent: %x\n",
811 * Check to see if we should unenforce flow control because
812 * ld (or user) finally read enuf data out of our queue.
814 * NOTE: This is done based on what the current flow control of the
817 * 1) HWFLOW (RTS) - Turn back on the UART's Receive interrupt.
818 * This will cause the UART's FIFO to raise RTS back up,
819 * which will allow the other side to start sending data again.
820 * 2) SWFLOW (IXOFF) - Send a start character to
821 * the other side, so it will start sending data to us again.
822 * 3) NONE - Do nothing. Since we didn't do anything to turn off the
823 * other side, we don't need to do anything now.
825 if (qleft
> (RQUEUESIZE
/ 2)) {
827 if (ch
->ch_c_cflag
& CRTSCTS
) {
828 if (ch
->ch_flags
& CH_RECEIVER_OFF
) {
829 bd_ops
->enable_receiver(ch
);
830 ch
->ch_flags
&= ~(CH_RECEIVER_OFF
);
831 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
832 "Internal queue hit lowlevel mark (%d)! Turning on interrupts\n",
837 else if (ch
->ch_c_iflag
& IXOFF
&& ch
->ch_stops_sent
) {
838 ch
->ch_stops_sent
= 0;
839 bd_ops
->send_start_character(ch
);
840 jsm_dbg(READ
, &ch
->ch_bd
->pci_dev
,
841 "Sending start char!\n");