xref: /openbmc/linux/drivers/video/fbdev/omap/sossi.c (revision 40662333)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * OMAP1 Special OptimiSed Screen Interface support
4  *
5  * Copyright (C) 2004-2005 Nokia Corporation
6  * Author: Juha Yrjölä <juha.yrjola@nokia.com>
7  */
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/clk.h>
11 #include <linux/irq.h>
12 #include <linux/io.h>
13 #include <linux/interrupt.h>
14 
15 #include <linux/omap-dma.h>
16 #include <linux/soc/ti/omap1-io.h>
17 
18 #include "omapfb.h"
19 #include "lcd_dma.h"
20 #include "lcdc.h"
21 
22 #define MODULE_NAME		"omapfb-sossi"
23 
24 #define OMAP_SOSSI_BASE         0xfffbac00
25 #define SOSSI_ID_REG		0x00
26 #define SOSSI_INIT1_REG		0x04
27 #define SOSSI_INIT2_REG		0x08
28 #define SOSSI_INIT3_REG		0x0c
29 #define SOSSI_FIFO_REG		0x10
30 #define SOSSI_REOTABLE_REG	0x14
31 #define SOSSI_TEARING_REG	0x18
32 #define SOSSI_INIT1B_REG	0x1c
33 #define SOSSI_FIFOB_REG		0x20
34 
35 #define DMA_GSCR          0xfffedc04
36 #define DMA_LCD_CCR       0xfffee3c2
37 #define DMA_LCD_CTRL      0xfffee3c4
38 #define DMA_LCD_LCH_CTRL  0xfffee3ea
39 
40 #define CONF_SOSSI_RESET_R      (1 << 23)
41 
42 #define RD_ACCESS		0
43 #define WR_ACCESS		1
44 
45 #define SOSSI_MAX_XMIT_BYTES	(512 * 1024)
46 
47 static struct {
48 	void __iomem	*base;
49 	struct clk	*fck;
50 	unsigned long	fck_hz;
51 	spinlock_t	lock;
52 	int		bus_pick_count;
53 	int		bus_pick_width;
54 	int		tearsync_mode;
55 	int		tearsync_line;
56 	void		(*lcdc_callback)(void *data);
57 	void		*lcdc_callback_data;
58 	int		vsync_dma_pending;
59 	/* timing for read and write access */
60 	int		clk_div;
61 	u8		clk_tw0[2];
62 	u8		clk_tw1[2];
63 	/*
64 	 * if last_access is the same as current we don't have to change
65 	 * the timings
66 	 */
67 	int		last_access;
68 
69 	struct omapfb_device	*fbdev;
70 } sossi;
71 
72 static inline u32 sossi_read_reg(int reg)
73 {
74 	return readl(sossi.base + reg);
75 }
76 
77 static inline u16 sossi_read_reg16(int reg)
78 {
79 	return readw(sossi.base + reg);
80 }
81 
82 static inline u8 sossi_read_reg8(int reg)
83 {
84 	return readb(sossi.base + reg);
85 }
86 
87 static inline void sossi_write_reg(int reg, u32 value)
88 {
89 	writel(value, sossi.base + reg);
90 }
91 
92 static inline void sossi_write_reg16(int reg, u16 value)
93 {
94 	writew(value, sossi.base + reg);
95 }
96 
97 static inline void sossi_write_reg8(int reg, u8 value)
98 {
99 	writeb(value, sossi.base + reg);
100 }
101 
102 static void sossi_set_bits(int reg, u32 bits)
103 {
104 	sossi_write_reg(reg, sossi_read_reg(reg) | bits);
105 }
106 
107 static void sossi_clear_bits(int reg, u32 bits)
108 {
109 	sossi_write_reg(reg, sossi_read_reg(reg) & ~bits);
110 }
111 
112 #define HZ_TO_PS(x)	(1000000000 / (x / 1000))
113 
114 static u32 ps_to_sossi_ticks(u32 ps, int div)
115 {
116 	u32 clk_period = HZ_TO_PS(sossi.fck_hz) * div;
117 	return (clk_period + ps - 1) / clk_period;
118 }
119 
120 static int calc_rd_timings(struct extif_timings *t)
121 {
122 	u32 tw0, tw1;
123 	int reon, reoff, recyc, actim;
124 	int div = t->clk_div;
125 
126 	/*
127 	 * Make sure that after conversion it still holds that:
128 	 * reoff > reon, recyc >= reoff, actim > reon
129 	 */
130 	reon = ps_to_sossi_ticks(t->re_on_time, div);
131 	/* reon will be exactly one sossi tick */
132 	if (reon > 1)
133 		return -1;
134 
135 	reoff = ps_to_sossi_ticks(t->re_off_time, div);
136 
137 	if (reoff <= reon)
138 		reoff = reon + 1;
139 
140 	tw0 = reoff - reon;
141 	if (tw0 > 0x10)
142 		return -1;
143 
144 	recyc = ps_to_sossi_ticks(t->re_cycle_time, div);
145 	if (recyc <= reoff)
146 		recyc = reoff + 1;
147 
148 	tw1 = recyc - tw0;
149 	/* values less then 3 result in the SOSSI block resetting itself */
150 	if (tw1 < 3)
151 		tw1 = 3;
152 	if (tw1 > 0x40)
153 		return -1;
154 
155 	actim = ps_to_sossi_ticks(t->access_time, div);
156 	if (actim < reoff)
157 		actim++;
158 	/*
159 	 * access time (data hold time) will be exactly one sossi
160 	 * tick
161 	 */
162 	if (actim - reoff > 1)
163 		return -1;
164 
165 	t->tim[0] = tw0 - 1;
166 	t->tim[1] = tw1 - 1;
167 
168 	return 0;
169 }
170 
171 static int calc_wr_timings(struct extif_timings *t)
172 {
173 	u32 tw0, tw1;
174 	int weon, weoff, wecyc;
175 	int div = t->clk_div;
176 
177 	/*
178 	 * Make sure that after conversion it still holds that:
179 	 * weoff > weon, wecyc >= weoff
180 	 */
181 	weon = ps_to_sossi_ticks(t->we_on_time, div);
182 	/* weon will be exactly one sossi tick */
183 	if (weon > 1)
184 		return -1;
185 
186 	weoff = ps_to_sossi_ticks(t->we_off_time, div);
187 	if (weoff <= weon)
188 		weoff = weon + 1;
189 	tw0 = weoff - weon;
190 	if (tw0 > 0x10)
191 		return -1;
192 
193 	wecyc = ps_to_sossi_ticks(t->we_cycle_time, div);
194 	if (wecyc <= weoff)
195 		wecyc = weoff + 1;
196 
197 	tw1 = wecyc - tw0;
198 	/* values less then 3 result in the SOSSI block resetting itself */
199 	if (tw1 < 3)
200 		tw1 = 3;
201 	if (tw1 > 0x40)
202 		return -1;
203 
204 	t->tim[2] = tw0 - 1;
205 	t->tim[3] = tw1 - 1;
206 
207 	return 0;
208 }
209 
210 static void _set_timing(int div, int tw0, int tw1)
211 {
212 	u32 l;
213 
214 #ifdef VERBOSE
215 	dev_dbg(sossi.fbdev->dev, "Using TW0 = %d, TW1 = %d, div = %d\n",
216 		 tw0 + 1, tw1 + 1, div);
217 #endif
218 
219 	clk_set_rate(sossi.fck, sossi.fck_hz / div);
220 	clk_enable(sossi.fck);
221 	l = sossi_read_reg(SOSSI_INIT1_REG);
222 	l &= ~((0x0f << 20) | (0x3f << 24));
223 	l |= (tw0 << 20) | (tw1 << 24);
224 	sossi_write_reg(SOSSI_INIT1_REG, l);
225 	clk_disable(sossi.fck);
226 }
227 
228 static void _set_bits_per_cycle(int bus_pick_count, int bus_pick_width)
229 {
230 	u32 l;
231 
232 	l = sossi_read_reg(SOSSI_INIT3_REG);
233 	l &= ~0x3ff;
234 	l |= ((bus_pick_count - 1) << 5) | ((bus_pick_width - 1) & 0x1f);
235 	sossi_write_reg(SOSSI_INIT3_REG, l);
236 }
237 
238 static void _set_tearsync_mode(int mode, unsigned line)
239 {
240 	u32 l;
241 
242 	l = sossi_read_reg(SOSSI_TEARING_REG);
243 	l &= ~(((1 << 11) - 1) << 15);
244 	l |= line << 15;
245 	l &= ~(0x3 << 26);
246 	l |= mode << 26;
247 	sossi_write_reg(SOSSI_TEARING_REG, l);
248 	if (mode)
249 		sossi_set_bits(SOSSI_INIT2_REG, 1 << 6);	/* TE logic */
250 	else
251 		sossi_clear_bits(SOSSI_INIT2_REG, 1 << 6);
252 }
253 
254 static inline void set_timing(int access)
255 {
256 	if (access != sossi.last_access) {
257 		sossi.last_access = access;
258 		_set_timing(sossi.clk_div,
259 			    sossi.clk_tw0[access], sossi.clk_tw1[access]);
260 	}
261 }
262 
263 static void sossi_start_transfer(void)
264 {
265 	/* WE */
266 	sossi_clear_bits(SOSSI_INIT2_REG, 1 << 4);
267 	/* CS active low */
268 	sossi_clear_bits(SOSSI_INIT1_REG, 1 << 30);
269 }
270 
271 static void sossi_stop_transfer(void)
272 {
273 	/* WE */
274 	sossi_set_bits(SOSSI_INIT2_REG, 1 << 4);
275 	/* CS active low */
276 	sossi_set_bits(SOSSI_INIT1_REG, 1 << 30);
277 }
278 
279 static void wait_end_of_write(void)
280 {
281 	/* Before reading we must check if some writings are going on */
282 	while (!(sossi_read_reg(SOSSI_INIT2_REG) & (1 << 3)));
283 }
284 
285 static void send_data(const void *data, unsigned int len)
286 {
287 	while (len >= 4) {
288 		sossi_write_reg(SOSSI_FIFO_REG, *(const u32 *) data);
289 		len -= 4;
290 		data += 4;
291 	}
292 	while (len >= 2) {
293 		sossi_write_reg16(SOSSI_FIFO_REG, *(const u16 *) data);
294 		len -= 2;
295 		data += 2;
296 	}
297 	while (len) {
298 		sossi_write_reg8(SOSSI_FIFO_REG, *(const u8 *) data);
299 		len--;
300 		data++;
301 	}
302 }
303 
304 static void set_cycles(unsigned int len)
305 {
306 	unsigned long nr_cycles = len / (sossi.bus_pick_width / 8);
307 
308 	BUG_ON((nr_cycles - 1) & ~0x3ffff);
309 
310 	sossi_clear_bits(SOSSI_INIT1_REG, 0x3ffff);
311 	sossi_set_bits(SOSSI_INIT1_REG, (nr_cycles - 1) & 0x3ffff);
312 }
313 
314 static int sossi_convert_timings(struct extif_timings *t)
315 {
316 	int r = 0;
317 	int div = t->clk_div;
318 
319 	t->converted = 0;
320 
321 	if (div <= 0 || div > 8)
322 		return -1;
323 
324 	/* no CS on SOSSI, so ignore cson, csoff, cs_pulsewidth */
325 	if ((r = calc_rd_timings(t)) < 0)
326 		return r;
327 
328 	if ((r = calc_wr_timings(t)) < 0)
329 		return r;
330 
331 	t->tim[4] = div;
332 
333 	t->converted = 1;
334 
335 	return 0;
336 }
337 
338 static void sossi_set_timings(const struct extif_timings *t)
339 {
340 	BUG_ON(!t->converted);
341 
342 	sossi.clk_tw0[RD_ACCESS] = t->tim[0];
343 	sossi.clk_tw1[RD_ACCESS] = t->tim[1];
344 
345 	sossi.clk_tw0[WR_ACCESS] = t->tim[2];
346 	sossi.clk_tw1[WR_ACCESS] = t->tim[3];
347 
348 	sossi.clk_div = t->tim[4];
349 }
350 
351 static void sossi_get_clk_info(u32 *clk_period, u32 *max_clk_div)
352 {
353 	*clk_period = HZ_TO_PS(sossi.fck_hz);
354 	*max_clk_div = 8;
355 }
356 
357 static void sossi_set_bits_per_cycle(int bpc)
358 {
359 	int bus_pick_count, bus_pick_width;
360 
361 	/*
362 	 * We set explicitly the bus_pick_count as well, although
363 	 * with remapping/reordering disabled it will be calculated by HW
364 	 * as (32 / bus_pick_width).
365 	 */
366 	switch (bpc) {
367 	case 8:
368 		bus_pick_count = 4;
369 		bus_pick_width = 8;
370 		break;
371 	case 16:
372 		bus_pick_count = 2;
373 		bus_pick_width = 16;
374 		break;
375 	default:
376 		BUG();
377 		return;
378 	}
379 	sossi.bus_pick_width = bus_pick_width;
380 	sossi.bus_pick_count = bus_pick_count;
381 }
382 
383 static int sossi_setup_tearsync(unsigned pin_cnt,
384 				unsigned hs_pulse_time, unsigned vs_pulse_time,
385 				int hs_pol_inv, int vs_pol_inv, int div)
386 {
387 	int hs, vs;
388 	u32 l;
389 
390 	if (pin_cnt != 1 || div < 1 || div > 8)
391 		return -EINVAL;
392 
393 	hs = ps_to_sossi_ticks(hs_pulse_time, div);
394 	vs = ps_to_sossi_ticks(vs_pulse_time, div);
395 	if (vs < 8 || vs <= hs || vs >= (1 << 12))
396 		return -EDOM;
397 	vs /= 8;
398 	vs--;
399 	if (hs > 8)
400 		hs = 8;
401 	if (hs)
402 		hs--;
403 
404 	dev_dbg(sossi.fbdev->dev,
405 		"setup_tearsync: hs %d vs %d hs_inv %d vs_inv %d\n",
406 		hs, vs, hs_pol_inv, vs_pol_inv);
407 
408 	clk_enable(sossi.fck);
409 	l = sossi_read_reg(SOSSI_TEARING_REG);
410 	l &= ~((1 << 15) - 1);
411 	l |= vs << 3;
412 	l |= hs;
413 	if (hs_pol_inv)
414 		l |= 1 << 29;
415 	else
416 		l &= ~(1 << 29);
417 	if (vs_pol_inv)
418 		l |= 1 << 28;
419 	else
420 		l &= ~(1 << 28);
421 	sossi_write_reg(SOSSI_TEARING_REG, l);
422 	clk_disable(sossi.fck);
423 
424 	return 0;
425 }
426 
427 static int sossi_enable_tearsync(int enable, unsigned line)
428 {
429 	int mode;
430 
431 	dev_dbg(sossi.fbdev->dev, "tearsync %d line %d\n", enable, line);
432 	if (line >= 1 << 11)
433 		return -EINVAL;
434 	if (enable) {
435 		if (line)
436 			mode = 2;		/* HS or VS */
437 		else
438 			mode = 3;		/* VS only */
439 	} else
440 		mode = 0;
441 	sossi.tearsync_line = line;
442 	sossi.tearsync_mode = mode;
443 
444 	return 0;
445 }
446 
447 static void sossi_write_command(const void *data, unsigned int len)
448 {
449 	clk_enable(sossi.fck);
450 	set_timing(WR_ACCESS);
451 	_set_bits_per_cycle(sossi.bus_pick_count, sossi.bus_pick_width);
452 	/* CMD#/DATA */
453 	sossi_clear_bits(SOSSI_INIT1_REG, 1 << 18);
454 	set_cycles(len);
455 	sossi_start_transfer();
456 	send_data(data, len);
457 	sossi_stop_transfer();
458 	wait_end_of_write();
459 	clk_disable(sossi.fck);
460 }
461 
462 static void sossi_write_data(const void *data, unsigned int len)
463 {
464 	clk_enable(sossi.fck);
465 	set_timing(WR_ACCESS);
466 	_set_bits_per_cycle(sossi.bus_pick_count, sossi.bus_pick_width);
467 	/* CMD#/DATA */
468 	sossi_set_bits(SOSSI_INIT1_REG, 1 << 18);
469 	set_cycles(len);
470 	sossi_start_transfer();
471 	send_data(data, len);
472 	sossi_stop_transfer();
473 	wait_end_of_write();
474 	clk_disable(sossi.fck);
475 }
476 
477 static void sossi_transfer_area(int width, int height,
478 				void (callback)(void *data), void *data)
479 {
480 	BUG_ON(callback == NULL);
481 
482 	sossi.lcdc_callback = callback;
483 	sossi.lcdc_callback_data = data;
484 
485 	clk_enable(sossi.fck);
486 	set_timing(WR_ACCESS);
487 	_set_bits_per_cycle(sossi.bus_pick_count, sossi.bus_pick_width);
488 	_set_tearsync_mode(sossi.tearsync_mode, sossi.tearsync_line);
489 	/* CMD#/DATA */
490 	sossi_set_bits(SOSSI_INIT1_REG, 1 << 18);
491 	set_cycles(width * height * sossi.bus_pick_width / 8);
492 
493 	sossi_start_transfer();
494 	if (sossi.tearsync_mode) {
495 		/*
496 		 * Wait for the sync signal and start the transfer only
497 		 * then. We can't seem to be able to use HW sync DMA for
498 		 * this since LCD DMA shows huge latencies, as if it
499 		 * would ignore some of the DMA requests from SoSSI.
500 		 */
501 		unsigned long flags;
502 
503 		spin_lock_irqsave(&sossi.lock, flags);
504 		sossi.vsync_dma_pending++;
505 		spin_unlock_irqrestore(&sossi.lock, flags);
506 	} else
507 		/* Just start the transfer right away. */
508 		omap_enable_lcd_dma();
509 }
510 
511 static void sossi_dma_callback(void *data)
512 {
513 	omap_stop_lcd_dma();
514 	sossi_stop_transfer();
515 	clk_disable(sossi.fck);
516 	sossi.lcdc_callback(sossi.lcdc_callback_data);
517 }
518 
519 static void sossi_read_data(void *data, unsigned int len)
520 {
521 	clk_enable(sossi.fck);
522 	set_timing(RD_ACCESS);
523 	_set_bits_per_cycle(sossi.bus_pick_count, sossi.bus_pick_width);
524 	/* CMD#/DATA */
525 	sossi_set_bits(SOSSI_INIT1_REG, 1 << 18);
526 	set_cycles(len);
527 	sossi_start_transfer();
528 	while (len >= 4) {
529 		*(u32 *) data = sossi_read_reg(SOSSI_FIFO_REG);
530 		len -= 4;
531 		data += 4;
532 	}
533 	while (len >= 2) {
534 		*(u16 *) data = sossi_read_reg16(SOSSI_FIFO_REG);
535 		len -= 2;
536 		data += 2;
537 	}
538 	while (len) {
539 		*(u8 *) data = sossi_read_reg8(SOSSI_FIFO_REG);
540 		len--;
541 		data++;
542 	}
543 	sossi_stop_transfer();
544 	clk_disable(sossi.fck);
545 }
546 
547 static irqreturn_t sossi_match_irq(int irq, void *data)
548 {
549 	unsigned long flags;
550 
551 	spin_lock_irqsave(&sossi.lock, flags);
552 	if (sossi.vsync_dma_pending) {
553 		sossi.vsync_dma_pending--;
554 		omap_enable_lcd_dma();
555 	}
556 	spin_unlock_irqrestore(&sossi.lock, flags);
557 	return IRQ_HANDLED;
558 }
559 
560 static int sossi_init(struct omapfb_device *fbdev)
561 {
562 	u32 l, k;
563 	struct clk *fck;
564 	struct clk *dpll1out_ck;
565 	int r;
566 
567 	sossi.base = ioremap(OMAP_SOSSI_BASE, SZ_1K);
568 	if (!sossi.base) {
569 		dev_err(fbdev->dev, "can't ioremap SoSSI\n");
570 		return -ENOMEM;
571 	}
572 
573 	sossi.fbdev = fbdev;
574 	spin_lock_init(&sossi.lock);
575 
576 	dpll1out_ck = clk_get(fbdev->dev, "ck_dpll1out");
577 	if (IS_ERR(dpll1out_ck)) {
578 		dev_err(fbdev->dev, "can't get DPLL1OUT clock\n");
579 		return PTR_ERR(dpll1out_ck);
580 	}
581 	/*
582 	 * We need the parent clock rate, which we might divide further
583 	 * depending on the timing requirements of the controller. See
584 	 * _set_timings.
585 	 */
586 	sossi.fck_hz = clk_get_rate(dpll1out_ck);
587 	clk_put(dpll1out_ck);
588 
589 	fck = clk_get(fbdev->dev, "ck_sossi");
590 	if (IS_ERR(fck)) {
591 		dev_err(fbdev->dev, "can't get SoSSI functional clock\n");
592 		return PTR_ERR(fck);
593 	}
594 	sossi.fck = fck;
595 
596 	/* Reset and enable the SoSSI module */
597 	l = omap_readl(MOD_CONF_CTRL_1);
598 	l |= CONF_SOSSI_RESET_R;
599 	omap_writel(l, MOD_CONF_CTRL_1);
600 	l &= ~CONF_SOSSI_RESET_R;
601 	omap_writel(l, MOD_CONF_CTRL_1);
602 
603 	clk_prepare_enable(sossi.fck);
604 	l = omap_readl(ARM_IDLECT2);
605 	l &= ~(1 << 8);			/* DMACK_REQ */
606 	omap_writel(l, ARM_IDLECT2);
607 
608 	l = sossi_read_reg(SOSSI_INIT2_REG);
609 	/* Enable and reset the SoSSI block */
610 	l |= (1 << 0) | (1 << 1);
611 	sossi_write_reg(SOSSI_INIT2_REG, l);
612 	/* Take SoSSI out of reset */
613 	l &= ~(1 << 1);
614 	sossi_write_reg(SOSSI_INIT2_REG, l);
615 
616 	sossi_write_reg(SOSSI_ID_REG, 0);
617 	l = sossi_read_reg(SOSSI_ID_REG);
618 	k = sossi_read_reg(SOSSI_ID_REG);
619 
620 	if (l != 0x55555555 || k != 0xaaaaaaaa) {
621 		dev_err(fbdev->dev,
622 			"invalid SoSSI sync pattern: %08x, %08x\n", l, k);
623 		r = -ENODEV;
624 		goto err;
625 	}
626 
627 	if ((r = omap_lcdc_set_dma_callback(sossi_dma_callback, NULL)) < 0) {
628 		dev_err(fbdev->dev, "can't get LCDC IRQ\n");
629 		r = -ENODEV;
630 		goto err;
631 	}
632 
633 	l = sossi_read_reg(SOSSI_ID_REG); /* Component code */
634 	l = sossi_read_reg(SOSSI_ID_REG);
635 	dev_info(fbdev->dev, "SoSSI version %d.%d initialized\n",
636 		l >> 16, l & 0xffff);
637 
638 	l = sossi_read_reg(SOSSI_INIT1_REG);
639 	l |= (1 << 19); /* DMA_MODE */
640 	l &= ~(1 << 31); /* REORDERING */
641 	sossi_write_reg(SOSSI_INIT1_REG, l);
642 
643 	if ((r = request_irq(fbdev->ext_irq, sossi_match_irq,
644 			     IRQ_TYPE_EDGE_FALLING,
645 	     "sossi_match", sossi.fbdev->dev)) < 0) {
646 		dev_err(sossi.fbdev->dev, "can't get SoSSI match IRQ\n");
647 		goto err;
648 	}
649 
650 	clk_disable(sossi.fck);
651 	return 0;
652 
653 err:
654 	clk_disable_unprepare(sossi.fck);
655 	clk_put(sossi.fck);
656 	return r;
657 }
658 
659 static void sossi_cleanup(void)
660 {
661 	omap_lcdc_free_dma_callback();
662 	clk_unprepare(sossi.fck);
663 	clk_put(sossi.fck);
664 	iounmap(sossi.base);
665 }
666 
667 struct lcd_ctrl_extif omap1_ext_if = {
668 	.init			= sossi_init,
669 	.cleanup		= sossi_cleanup,
670 	.get_clk_info		= sossi_get_clk_info,
671 	.convert_timings	= sossi_convert_timings,
672 	.set_timings		= sossi_set_timings,
673 	.set_bits_per_cycle	= sossi_set_bits_per_cycle,
674 	.setup_tearsync		= sossi_setup_tearsync,
675 	.enable_tearsync	= sossi_enable_tearsync,
676 	.write_command		= sossi_write_command,
677 	.read_data		= sossi_read_data,
678 	.write_data		= sossi_write_data,
679 	.transfer_area		= sossi_transfer_area,
680 
681 	.max_transmit_size	= SOSSI_MAX_XMIT_BYTES,
682 };
683 
684