xref: /openbmc/linux/drivers/ptp/ptp_pch.c (revision ce746d43)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * PTP 1588 clock using the EG20T PCH
4  *
5  * Copyright (C) 2010 OMICRON electronics GmbH
6  * Copyright (C) 2011-2012 LAPIS SEMICONDUCTOR Co., LTD.
7  *
8  * This code was derived from the IXP46X driver.
9  */
10 
11 #include <linux/device.h>
12 #include <linux/err.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/io.h>
16 #include <linux/irq.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/pci.h>
20 #include <linux/ptp_clock_kernel.h>
21 #include <linux/slab.h>
22 
23 #define STATION_ADDR_LEN	20
24 #define PCI_DEVICE_ID_PCH_1588	0x8819
25 #define IO_MEM_BAR 1
26 
27 #define DEFAULT_ADDEND 0xA0000000
28 #define TICKS_NS_SHIFT  5
29 #define N_EXT_TS	2
30 
31 enum pch_status {
32 	PCH_SUCCESS,
33 	PCH_INVALIDPARAM,
34 	PCH_NOTIMESTAMP,
35 	PCH_INTERRUPTMODEINUSE,
36 	PCH_FAILED,
37 	PCH_UNSUPPORTED,
38 };
39 /**
40  * struct pch_ts_regs - IEEE 1588 registers
41  */
42 struct pch_ts_regs {
43 	u32 control;
44 	u32 event;
45 	u32 addend;
46 	u32 accum;
47 	u32 test;
48 	u32 ts_compare;
49 	u32 rsystime_lo;
50 	u32 rsystime_hi;
51 	u32 systime_lo;
52 	u32 systime_hi;
53 	u32 trgt_lo;
54 	u32 trgt_hi;
55 	u32 asms_lo;
56 	u32 asms_hi;
57 	u32 amms_lo;
58 	u32 amms_hi;
59 	u32 ch_control;
60 	u32 ch_event;
61 	u32 tx_snap_lo;
62 	u32 tx_snap_hi;
63 	u32 rx_snap_lo;
64 	u32 rx_snap_hi;
65 	u32 src_uuid_lo;
66 	u32 src_uuid_hi;
67 	u32 can_status;
68 	u32 can_snap_lo;
69 	u32 can_snap_hi;
70 	u32 ts_sel;
71 	u32 ts_st[6];
72 	u32 reserve1[14];
73 	u32 stl_max_set_en;
74 	u32 stl_max_set;
75 	u32 reserve2[13];
76 	u32 srst;
77 };
78 
79 #define PCH_TSC_RESET		(1 << 0)
80 #define PCH_TSC_TTM_MASK	(1 << 1)
81 #define PCH_TSC_ASMS_MASK	(1 << 2)
82 #define PCH_TSC_AMMS_MASK	(1 << 3)
83 #define PCH_TSC_PPSM_MASK	(1 << 4)
84 #define PCH_TSE_TTIPEND		(1 << 1)
85 #define PCH_TSE_SNS		(1 << 2)
86 #define PCH_TSE_SNM		(1 << 3)
87 #define PCH_TSE_PPS		(1 << 4)
88 #define PCH_CC_MM		(1 << 0)
89 #define PCH_CC_TA		(1 << 1)
90 
91 #define PCH_CC_MODE_SHIFT	16
92 #define PCH_CC_MODE_MASK	0x001F0000
93 #define PCH_CC_VERSION		(1 << 31)
94 #define PCH_CE_TXS		(1 << 0)
95 #define PCH_CE_RXS		(1 << 1)
96 #define PCH_CE_OVR		(1 << 0)
97 #define PCH_CE_VAL		(1 << 1)
98 #define PCH_ECS_ETH		(1 << 0)
99 
100 #define PCH_ECS_CAN		(1 << 1)
101 #define PCH_STATION_BYTES	6
102 
103 #define PCH_IEEE1588_ETH	(1 << 0)
104 #define PCH_IEEE1588_CAN	(1 << 1)
105 /**
106  * struct pch_dev - Driver private data
107  */
108 struct pch_dev {
109 	struct pch_ts_regs __iomem *regs;
110 	struct ptp_clock *ptp_clock;
111 	struct ptp_clock_info caps;
112 	int exts0_enabled;
113 	int exts1_enabled;
114 
115 	u32 mem_base;
116 	u32 mem_size;
117 	u32 irq;
118 	struct pci_dev *pdev;
119 	spinlock_t register_lock;
120 };
121 
122 /**
123  * struct pch_params - 1588 module parameter
124  */
125 struct pch_params {
126 	u8 station[STATION_ADDR_LEN];
127 };
128 
129 /* structure to hold the module parameters */
130 static struct pch_params pch_param = {
131 	"00:00:00:00:00:00"
132 };
133 
134 /*
135  * Register access functions
136  */
137 static inline void pch_eth_enable_set(struct pch_dev *chip)
138 {
139 	u32 val;
140 	/* SET the eth_enable bit */
141 	val = ioread32(&chip->regs->ts_sel) | (PCH_ECS_ETH);
142 	iowrite32(val, (&chip->regs->ts_sel));
143 }
144 
145 static u64 pch_systime_read(struct pch_ts_regs __iomem *regs)
146 {
147 	u64 ns;
148 	u32 lo, hi;
149 
150 	lo = ioread32(&regs->systime_lo);
151 	hi = ioread32(&regs->systime_hi);
152 
153 	ns = ((u64) hi) << 32;
154 	ns |= lo;
155 	ns <<= TICKS_NS_SHIFT;
156 
157 	return ns;
158 }
159 
160 static void pch_systime_write(struct pch_ts_regs __iomem *regs, u64 ns)
161 {
162 	u32 hi, lo;
163 
164 	ns >>= TICKS_NS_SHIFT;
165 	hi = ns >> 32;
166 	lo = ns & 0xffffffff;
167 
168 	iowrite32(lo, &regs->systime_lo);
169 	iowrite32(hi, &regs->systime_hi);
170 }
171 
172 static inline void pch_block_reset(struct pch_dev *chip)
173 {
174 	u32 val;
175 	/* Reset Hardware Assist block */
176 	val = ioread32(&chip->regs->control) | PCH_TSC_RESET;
177 	iowrite32(val, (&chip->regs->control));
178 	val = val & ~PCH_TSC_RESET;
179 	iowrite32(val, (&chip->regs->control));
180 }
181 
182 u32 pch_ch_control_read(struct pci_dev *pdev)
183 {
184 	struct pch_dev *chip = pci_get_drvdata(pdev);
185 	u32 val;
186 
187 	val = ioread32(&chip->regs->ch_control);
188 
189 	return val;
190 }
191 EXPORT_SYMBOL(pch_ch_control_read);
192 
193 void pch_ch_control_write(struct pci_dev *pdev, u32 val)
194 {
195 	struct pch_dev *chip = pci_get_drvdata(pdev);
196 
197 	iowrite32(val, (&chip->regs->ch_control));
198 }
199 EXPORT_SYMBOL(pch_ch_control_write);
200 
201 u32 pch_ch_event_read(struct pci_dev *pdev)
202 {
203 	struct pch_dev *chip = pci_get_drvdata(pdev);
204 	u32 val;
205 
206 	val = ioread32(&chip->regs->ch_event);
207 
208 	return val;
209 }
210 EXPORT_SYMBOL(pch_ch_event_read);
211 
212 void pch_ch_event_write(struct pci_dev *pdev, u32 val)
213 {
214 	struct pch_dev *chip = pci_get_drvdata(pdev);
215 
216 	iowrite32(val, (&chip->regs->ch_event));
217 }
218 EXPORT_SYMBOL(pch_ch_event_write);
219 
220 u32 pch_src_uuid_lo_read(struct pci_dev *pdev)
221 {
222 	struct pch_dev *chip = pci_get_drvdata(pdev);
223 	u32 val;
224 
225 	val = ioread32(&chip->regs->src_uuid_lo);
226 
227 	return val;
228 }
229 EXPORT_SYMBOL(pch_src_uuid_lo_read);
230 
231 u32 pch_src_uuid_hi_read(struct pci_dev *pdev)
232 {
233 	struct pch_dev *chip = pci_get_drvdata(pdev);
234 	u32 val;
235 
236 	val = ioread32(&chip->regs->src_uuid_hi);
237 
238 	return val;
239 }
240 EXPORT_SYMBOL(pch_src_uuid_hi_read);
241 
242 u64 pch_rx_snap_read(struct pci_dev *pdev)
243 {
244 	struct pch_dev *chip = pci_get_drvdata(pdev);
245 	u64 ns;
246 	u32 lo, hi;
247 
248 	lo = ioread32(&chip->regs->rx_snap_lo);
249 	hi = ioread32(&chip->regs->rx_snap_hi);
250 
251 	ns = ((u64) hi) << 32;
252 	ns |= lo;
253 	ns <<= TICKS_NS_SHIFT;
254 
255 	return ns;
256 }
257 EXPORT_SYMBOL(pch_rx_snap_read);
258 
259 u64 pch_tx_snap_read(struct pci_dev *pdev)
260 {
261 	struct pch_dev *chip = pci_get_drvdata(pdev);
262 	u64 ns;
263 	u32 lo, hi;
264 
265 	lo = ioread32(&chip->regs->tx_snap_lo);
266 	hi = ioread32(&chip->regs->tx_snap_hi);
267 
268 	ns = ((u64) hi) << 32;
269 	ns |= lo;
270 	ns <<= TICKS_NS_SHIFT;
271 
272 	return ns;
273 }
274 EXPORT_SYMBOL(pch_tx_snap_read);
275 
276 /* This function enables all 64 bits in system time registers [high & low].
277 This is a work-around for non continuous value in the SystemTime Register*/
278 static void pch_set_system_time_count(struct pch_dev *chip)
279 {
280 	iowrite32(0x01, &chip->regs->stl_max_set_en);
281 	iowrite32(0xFFFFFFFF, &chip->regs->stl_max_set);
282 	iowrite32(0x00, &chip->regs->stl_max_set_en);
283 }
284 
285 static void pch_reset(struct pch_dev *chip)
286 {
287 	/* Reset Hardware Assist */
288 	pch_block_reset(chip);
289 
290 	/* enable all 32 bits in system time registers */
291 	pch_set_system_time_count(chip);
292 }
293 
294 /**
295  * pch_set_station_address() - This API sets the station address used by
296  *				    IEEE 1588 hardware when looking at PTP
297  *				    traffic on the  ethernet interface
298  * @addr:	dress which contain the column separated address to be used.
299  */
300 int pch_set_station_address(u8 *addr, struct pci_dev *pdev)
301 {
302 	s32 i;
303 	struct pch_dev *chip = pci_get_drvdata(pdev);
304 
305 	/* Verify the parameter */
306 	if ((chip->regs == NULL) || addr == (u8 *)NULL) {
307 		dev_err(&pdev->dev,
308 			"invalid params returning PCH_INVALIDPARAM\n");
309 		return PCH_INVALIDPARAM;
310 	}
311 	/* For all station address bytes */
312 	for (i = 0; i < PCH_STATION_BYTES; i++) {
313 		u32 val;
314 		s32 tmp;
315 
316 		tmp = hex_to_bin(addr[i * 3]);
317 		if (tmp < 0) {
318 			dev_err(&pdev->dev,
319 				"invalid params returning PCH_INVALIDPARAM\n");
320 			return PCH_INVALIDPARAM;
321 		}
322 		val = tmp * 16;
323 		tmp = hex_to_bin(addr[(i * 3) + 1]);
324 		if (tmp < 0) {
325 			dev_err(&pdev->dev,
326 				"invalid params returning PCH_INVALIDPARAM\n");
327 			return PCH_INVALIDPARAM;
328 		}
329 		val += tmp;
330 		/* Expects ':' separated addresses */
331 		if ((i < 5) && (addr[(i * 3) + 2] != ':')) {
332 			dev_err(&pdev->dev,
333 				"invalid params returning PCH_INVALIDPARAM\n");
334 			return PCH_INVALIDPARAM;
335 		}
336 
337 		/* Ideally we should set the address only after validating
338 							 entire string */
339 		dev_dbg(&pdev->dev, "invoking pch_station_set\n");
340 		iowrite32(val, &chip->regs->ts_st[i]);
341 	}
342 	return 0;
343 }
344 EXPORT_SYMBOL(pch_set_station_address);
345 
346 /*
347  * Interrupt service routine
348  */
349 static irqreturn_t isr(int irq, void *priv)
350 {
351 	struct pch_dev *pch_dev = priv;
352 	struct pch_ts_regs __iomem *regs = pch_dev->regs;
353 	struct ptp_clock_event event;
354 	u32 ack = 0, lo, hi, val;
355 
356 	val = ioread32(&regs->event);
357 
358 	if (val & PCH_TSE_SNS) {
359 		ack |= PCH_TSE_SNS;
360 		if (pch_dev->exts0_enabled) {
361 			hi = ioread32(&regs->asms_hi);
362 			lo = ioread32(&regs->asms_lo);
363 			event.type = PTP_CLOCK_EXTTS;
364 			event.index = 0;
365 			event.timestamp = ((u64) hi) << 32;
366 			event.timestamp |= lo;
367 			event.timestamp <<= TICKS_NS_SHIFT;
368 			ptp_clock_event(pch_dev->ptp_clock, &event);
369 		}
370 	}
371 
372 	if (val & PCH_TSE_SNM) {
373 		ack |= PCH_TSE_SNM;
374 		if (pch_dev->exts1_enabled) {
375 			hi = ioread32(&regs->amms_hi);
376 			lo = ioread32(&regs->amms_lo);
377 			event.type = PTP_CLOCK_EXTTS;
378 			event.index = 1;
379 			event.timestamp = ((u64) hi) << 32;
380 			event.timestamp |= lo;
381 			event.timestamp <<= TICKS_NS_SHIFT;
382 			ptp_clock_event(pch_dev->ptp_clock, &event);
383 		}
384 	}
385 
386 	if (val & PCH_TSE_TTIPEND)
387 		ack |= PCH_TSE_TTIPEND; /* this bit seems to be always set */
388 
389 	if (ack) {
390 		iowrite32(ack, &regs->event);
391 		return IRQ_HANDLED;
392 	} else
393 		return IRQ_NONE;
394 }
395 
396 /*
397  * PTP clock operations
398  */
399 
400 static int ptp_pch_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
401 {
402 	u64 adj;
403 	u32 diff, addend;
404 	int neg_adj = 0;
405 	struct pch_dev *pch_dev = container_of(ptp, struct pch_dev, caps);
406 	struct pch_ts_regs __iomem *regs = pch_dev->regs;
407 
408 	if (ppb < 0) {
409 		neg_adj = 1;
410 		ppb = -ppb;
411 	}
412 	addend = DEFAULT_ADDEND;
413 	adj = addend;
414 	adj *= ppb;
415 	diff = div_u64(adj, 1000000000ULL);
416 
417 	addend = neg_adj ? addend - diff : addend + diff;
418 
419 	iowrite32(addend, &regs->addend);
420 
421 	return 0;
422 }
423 
424 static int ptp_pch_adjtime(struct ptp_clock_info *ptp, s64 delta)
425 {
426 	s64 now;
427 	unsigned long flags;
428 	struct pch_dev *pch_dev = container_of(ptp, struct pch_dev, caps);
429 	struct pch_ts_regs __iomem *regs = pch_dev->regs;
430 
431 	spin_lock_irqsave(&pch_dev->register_lock, flags);
432 	now = pch_systime_read(regs);
433 	now += delta;
434 	pch_systime_write(regs, now);
435 	spin_unlock_irqrestore(&pch_dev->register_lock, flags);
436 
437 	return 0;
438 }
439 
440 static int ptp_pch_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
441 {
442 	u64 ns;
443 	unsigned long flags;
444 	struct pch_dev *pch_dev = container_of(ptp, struct pch_dev, caps);
445 	struct pch_ts_regs __iomem *regs = pch_dev->regs;
446 
447 	spin_lock_irqsave(&pch_dev->register_lock, flags);
448 	ns = pch_systime_read(regs);
449 	spin_unlock_irqrestore(&pch_dev->register_lock, flags);
450 
451 	*ts = ns_to_timespec64(ns);
452 	return 0;
453 }
454 
455 static int ptp_pch_settime(struct ptp_clock_info *ptp,
456 			   const struct timespec64 *ts)
457 {
458 	u64 ns;
459 	unsigned long flags;
460 	struct pch_dev *pch_dev = container_of(ptp, struct pch_dev, caps);
461 	struct pch_ts_regs __iomem *regs = pch_dev->regs;
462 
463 	ns = timespec64_to_ns(ts);
464 
465 	spin_lock_irqsave(&pch_dev->register_lock, flags);
466 	pch_systime_write(regs, ns);
467 	spin_unlock_irqrestore(&pch_dev->register_lock, flags);
468 
469 	return 0;
470 }
471 
472 static int ptp_pch_enable(struct ptp_clock_info *ptp,
473 			  struct ptp_clock_request *rq, int on)
474 {
475 	struct pch_dev *pch_dev = container_of(ptp, struct pch_dev, caps);
476 
477 	switch (rq->type) {
478 	case PTP_CLK_REQ_EXTTS:
479 		switch (rq->extts.index) {
480 		case 0:
481 			pch_dev->exts0_enabled = on ? 1 : 0;
482 			break;
483 		case 1:
484 			pch_dev->exts1_enabled = on ? 1 : 0;
485 			break;
486 		default:
487 			return -EINVAL;
488 		}
489 		return 0;
490 	default:
491 		break;
492 	}
493 
494 	return -EOPNOTSUPP;
495 }
496 
497 static const struct ptp_clock_info ptp_pch_caps = {
498 	.owner		= THIS_MODULE,
499 	.name		= "PCH timer",
500 	.max_adj	= 50000000,
501 	.n_ext_ts	= N_EXT_TS,
502 	.n_pins		= 0,
503 	.pps		= 0,
504 	.adjfreq	= ptp_pch_adjfreq,
505 	.adjtime	= ptp_pch_adjtime,
506 	.gettime64	= ptp_pch_gettime,
507 	.settime64	= ptp_pch_settime,
508 	.enable		= ptp_pch_enable,
509 };
510 
511 #define pch_suspend NULL
512 #define pch_resume NULL
513 
514 static void pch_remove(struct pci_dev *pdev)
515 {
516 	struct pch_dev *chip = pci_get_drvdata(pdev);
517 
518 	ptp_clock_unregister(chip->ptp_clock);
519 	/* free the interrupt */
520 	if (pdev->irq != 0)
521 		free_irq(pdev->irq, chip);
522 
523 	/* unmap the virtual IO memory space */
524 	if (chip->regs != NULL) {
525 		iounmap(chip->regs);
526 		chip->regs = NULL;
527 	}
528 	/* release the reserved IO memory space */
529 	if (chip->mem_base != 0) {
530 		release_mem_region(chip->mem_base, chip->mem_size);
531 		chip->mem_base = 0;
532 	}
533 	pci_disable_device(pdev);
534 	kfree(chip);
535 	dev_info(&pdev->dev, "complete\n");
536 }
537 
538 static s32
539 pch_probe(struct pci_dev *pdev, const struct pci_device_id *id)
540 {
541 	s32 ret;
542 	unsigned long flags;
543 	struct pch_dev *chip;
544 
545 	chip = kzalloc(sizeof(struct pch_dev), GFP_KERNEL);
546 	if (chip == NULL)
547 		return -ENOMEM;
548 
549 	/* enable the 1588 pci device */
550 	ret = pci_enable_device(pdev);
551 	if (ret != 0) {
552 		dev_err(&pdev->dev, "could not enable the pci device\n");
553 		goto err_pci_en;
554 	}
555 
556 	chip->mem_base = pci_resource_start(pdev, IO_MEM_BAR);
557 	if (!chip->mem_base) {
558 		dev_err(&pdev->dev, "could not locate IO memory address\n");
559 		ret = -ENODEV;
560 		goto err_pci_start;
561 	}
562 
563 	/* retrieve the available length of the IO memory space */
564 	chip->mem_size = pci_resource_len(pdev, IO_MEM_BAR);
565 
566 	/* allocate the memory for the device registers */
567 	if (!request_mem_region(chip->mem_base, chip->mem_size, "1588_regs")) {
568 		dev_err(&pdev->dev,
569 			"could not allocate register memory space\n");
570 		ret = -EBUSY;
571 		goto err_req_mem_region;
572 	}
573 
574 	/* get the virtual address to the 1588 registers */
575 	chip->regs = ioremap(chip->mem_base, chip->mem_size);
576 
577 	if (!chip->regs) {
578 		dev_err(&pdev->dev, "Could not get virtual address\n");
579 		ret = -ENOMEM;
580 		goto err_ioremap;
581 	}
582 
583 	chip->caps = ptp_pch_caps;
584 	chip->ptp_clock = ptp_clock_register(&chip->caps, &pdev->dev);
585 	if (IS_ERR(chip->ptp_clock)) {
586 		ret = PTR_ERR(chip->ptp_clock);
587 		goto err_ptp_clock_reg;
588 	}
589 
590 	spin_lock_init(&chip->register_lock);
591 
592 	ret = request_irq(pdev->irq, &isr, IRQF_SHARED, KBUILD_MODNAME, chip);
593 	if (ret != 0) {
594 		dev_err(&pdev->dev, "failed to get irq %d\n", pdev->irq);
595 		goto err_req_irq;
596 	}
597 
598 	/* indicate success */
599 	chip->irq = pdev->irq;
600 	chip->pdev = pdev;
601 	pci_set_drvdata(pdev, chip);
602 
603 	spin_lock_irqsave(&chip->register_lock, flags);
604 	/* reset the ieee1588 h/w */
605 	pch_reset(chip);
606 
607 	iowrite32(DEFAULT_ADDEND, &chip->regs->addend);
608 	iowrite32(1, &chip->regs->trgt_lo);
609 	iowrite32(0, &chip->regs->trgt_hi);
610 	iowrite32(PCH_TSE_TTIPEND, &chip->regs->event);
611 
612 	pch_eth_enable_set(chip);
613 
614 	if (strcmp(pch_param.station, "00:00:00:00:00:00") != 0) {
615 		if (pch_set_station_address(pch_param.station, pdev) != 0) {
616 			dev_err(&pdev->dev,
617 			"Invalid station address parameter\n"
618 			"Module loaded but station address not set correctly\n"
619 			);
620 		}
621 	}
622 	spin_unlock_irqrestore(&chip->register_lock, flags);
623 	return 0;
624 
625 err_req_irq:
626 	ptp_clock_unregister(chip->ptp_clock);
627 err_ptp_clock_reg:
628 	iounmap(chip->regs);
629 	chip->regs = NULL;
630 
631 err_ioremap:
632 	release_mem_region(chip->mem_base, chip->mem_size);
633 
634 err_req_mem_region:
635 	chip->mem_base = 0;
636 
637 err_pci_start:
638 	pci_disable_device(pdev);
639 
640 err_pci_en:
641 	kfree(chip);
642 	dev_err(&pdev->dev, "probe failed(ret=0x%x)\n", ret);
643 
644 	return ret;
645 }
646 
647 static const struct pci_device_id pch_ieee1588_pcidev_id[] = {
648 	{
649 	  .vendor = PCI_VENDOR_ID_INTEL,
650 	  .device = PCI_DEVICE_ID_PCH_1588
651 	 },
652 	{0}
653 };
654 
655 static SIMPLE_DEV_PM_OPS(pch_pm_ops, pch_suspend, pch_resume);
656 
657 static struct pci_driver pch_driver = {
658 	.name = KBUILD_MODNAME,
659 	.id_table = pch_ieee1588_pcidev_id,
660 	.probe = pch_probe,
661 	.remove = pch_remove,
662 	.driver.pm = &pch_pm_ops,
663 };
664 
665 static void __exit ptp_pch_exit(void)
666 {
667 	pci_unregister_driver(&pch_driver);
668 }
669 
670 static s32 __init ptp_pch_init(void)
671 {
672 	s32 ret;
673 
674 	/* register the driver with the pci core */
675 	ret = pci_register_driver(&pch_driver);
676 
677 	return ret;
678 }
679 
680 module_init(ptp_pch_init);
681 module_exit(ptp_pch_exit);
682 
683 module_param_string(station,
684 		    pch_param.station, sizeof(pch_param.station), 0444);
685 MODULE_PARM_DESC(station,
686 	 "IEEE 1588 station address to use - colon separated hex values");
687 
688 MODULE_AUTHOR("LAPIS SEMICONDUCTOR, <tshimizu818@gmail.com>");
689 MODULE_DESCRIPTION("PTP clock using the EG20T timer");
690 MODULE_LICENSE("GPL");
691