1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
4  *
5  * Driver for the ARC EMAC 10100 (hardware revision 5)
6  *
7  * Contributors:
8  *		Amit Bhor
9  *		Sameer Dhavale
10  *		Vineet Gupta
11  */
12 
13 #include <linux/crc32.h>
14 #include <linux/etherdevice.h>
15 #include <linux/interrupt.h>
16 #include <linux/io.h>
17 #include <linux/module.h>
18 #include <linux/of_address.h>
19 #include <linux/of_irq.h>
20 #include <linux/of_mdio.h>
21 #include <linux/of_net.h>
22 #include <linux/of_platform.h>
23 
24 #include "emac.h"
25 
26 static void arc_emac_restart(struct net_device *ndev);
27 
28 /**
29  * arc_emac_tx_avail - Return the number of available slots in the tx ring.
30  * @priv: Pointer to ARC EMAC private data structure.
31  *
32  * returns: the number of slots available for transmission in tx the ring.
33  */
34 static inline int arc_emac_tx_avail(struct arc_emac_priv *priv)
35 {
36 	return (priv->txbd_dirty + TX_BD_NUM - priv->txbd_curr - 1) % TX_BD_NUM;
37 }
38 
39 /**
40  * arc_emac_adjust_link - Adjust the PHY link duplex.
41  * @ndev:	Pointer to the net_device structure.
42  *
43  * This function is called to change the duplex setting after auto negotiation
44  * is done by the PHY.
45  */
46 static void arc_emac_adjust_link(struct net_device *ndev)
47 {
48 	struct arc_emac_priv *priv = netdev_priv(ndev);
49 	struct phy_device *phy_dev = ndev->phydev;
50 	unsigned int reg, state_changed = 0;
51 
52 	if (priv->link != phy_dev->link) {
53 		priv->link = phy_dev->link;
54 		state_changed = 1;
55 	}
56 
57 	if (priv->speed != phy_dev->speed) {
58 		priv->speed = phy_dev->speed;
59 		state_changed = 1;
60 		if (priv->set_mac_speed)
61 			priv->set_mac_speed(priv, priv->speed);
62 	}
63 
64 	if (priv->duplex != phy_dev->duplex) {
65 		reg = arc_reg_get(priv, R_CTRL);
66 
67 		if (phy_dev->duplex == DUPLEX_FULL)
68 			reg |= ENFL_MASK;
69 		else
70 			reg &= ~ENFL_MASK;
71 
72 		arc_reg_set(priv, R_CTRL, reg);
73 		priv->duplex = phy_dev->duplex;
74 		state_changed = 1;
75 	}
76 
77 	if (state_changed)
78 		phy_print_status(phy_dev);
79 }
80 
81 /**
82  * arc_emac_get_drvinfo - Get EMAC driver information.
83  * @ndev:	Pointer to net_device structure.
84  * @info:	Pointer to ethtool_drvinfo structure.
85  *
86  * This implements ethtool command for getting the driver information.
87  * Issue "ethtool -i ethX" under linux prompt to execute this function.
88  */
89 static void arc_emac_get_drvinfo(struct net_device *ndev,
90 				 struct ethtool_drvinfo *info)
91 {
92 	struct arc_emac_priv *priv = netdev_priv(ndev);
93 
94 	strlcpy(info->driver, priv->drv_name, sizeof(info->driver));
95 }
96 
97 static const struct ethtool_ops arc_emac_ethtool_ops = {
98 	.get_drvinfo	= arc_emac_get_drvinfo,
99 	.get_link	= ethtool_op_get_link,
100 	.get_link_ksettings = phy_ethtool_get_link_ksettings,
101 	.set_link_ksettings = phy_ethtool_set_link_ksettings,
102 };
103 
104 #define FIRST_OR_LAST_MASK	(FIRST_MASK | LAST_MASK)
105 
106 /**
107  * arc_emac_tx_clean - clears processed by EMAC Tx BDs.
108  * @ndev:	Pointer to the network device.
109  */
110 static void arc_emac_tx_clean(struct net_device *ndev)
111 {
112 	struct arc_emac_priv *priv = netdev_priv(ndev);
113 	struct net_device_stats *stats = &ndev->stats;
114 	unsigned int i;
115 
116 	for (i = 0; i < TX_BD_NUM; i++) {
117 		unsigned int *txbd_dirty = &priv->txbd_dirty;
118 		struct arc_emac_bd *txbd = &priv->txbd[*txbd_dirty];
119 		struct buffer_state *tx_buff = &priv->tx_buff[*txbd_dirty];
120 		struct sk_buff *skb = tx_buff->skb;
121 		unsigned int info = le32_to_cpu(txbd->info);
122 
123 		if ((info & FOR_EMAC) || !txbd->data || !skb)
124 			break;
125 
126 		if (unlikely(info & (DROP | DEFR | LTCL | UFLO))) {
127 			stats->tx_errors++;
128 			stats->tx_dropped++;
129 
130 			if (info & DEFR)
131 				stats->tx_carrier_errors++;
132 
133 			if (info & LTCL)
134 				stats->collisions++;
135 
136 			if (info & UFLO)
137 				stats->tx_fifo_errors++;
138 		} else if (likely(info & FIRST_OR_LAST_MASK)) {
139 			stats->tx_packets++;
140 			stats->tx_bytes += skb->len;
141 		}
142 
143 		dma_unmap_single(&ndev->dev, dma_unmap_addr(tx_buff, addr),
144 				 dma_unmap_len(tx_buff, len), DMA_TO_DEVICE);
145 
146 		/* return the sk_buff to system */
147 		dev_consume_skb_irq(skb);
148 
149 		txbd->data = 0;
150 		txbd->info = 0;
151 		tx_buff->skb = NULL;
152 
153 		*txbd_dirty = (*txbd_dirty + 1) % TX_BD_NUM;
154 	}
155 
156 	/* Ensure that txbd_dirty is visible to tx() before checking
157 	 * for queue stopped.
158 	 */
159 	smp_mb();
160 
161 	if (netif_queue_stopped(ndev) && arc_emac_tx_avail(priv))
162 		netif_wake_queue(ndev);
163 }
164 
165 /**
166  * arc_emac_rx - processing of Rx packets.
167  * @ndev:	Pointer to the network device.
168  * @budget:	How many BDs to process on 1 call.
169  *
170  * returns:	Number of processed BDs
171  *
172  * Iterate through Rx BDs and deliver received packages to upper layer.
173  */
174 static int arc_emac_rx(struct net_device *ndev, int budget)
175 {
176 	struct arc_emac_priv *priv = netdev_priv(ndev);
177 	unsigned int work_done;
178 
179 	for (work_done = 0; work_done < budget; work_done++) {
180 		unsigned int *last_rx_bd = &priv->last_rx_bd;
181 		struct net_device_stats *stats = &ndev->stats;
182 		struct buffer_state *rx_buff = &priv->rx_buff[*last_rx_bd];
183 		struct arc_emac_bd *rxbd = &priv->rxbd[*last_rx_bd];
184 		unsigned int pktlen, info = le32_to_cpu(rxbd->info);
185 		struct sk_buff *skb;
186 		dma_addr_t addr;
187 
188 		if (unlikely((info & OWN_MASK) == FOR_EMAC))
189 			break;
190 
191 		/* Make a note that we saw a packet at this BD.
192 		 * So next time, driver starts from this + 1
193 		 */
194 		*last_rx_bd = (*last_rx_bd + 1) % RX_BD_NUM;
195 
196 		if (unlikely((info & FIRST_OR_LAST_MASK) !=
197 			     FIRST_OR_LAST_MASK)) {
198 			/* We pre-allocate buffers of MTU size so incoming
199 			 * packets won't be split/chained.
200 			 */
201 			if (net_ratelimit())
202 				netdev_err(ndev, "incomplete packet received\n");
203 
204 			/* Return ownership to EMAC */
205 			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
206 			stats->rx_errors++;
207 			stats->rx_length_errors++;
208 			continue;
209 		}
210 
211 		/* Prepare the BD for next cycle. netif_receive_skb()
212 		 * only if new skb was allocated and mapped to avoid holes
213 		 * in the RX fifo.
214 		 */
215 		skb = netdev_alloc_skb_ip_align(ndev, EMAC_BUFFER_SIZE);
216 		if (unlikely(!skb)) {
217 			if (net_ratelimit())
218 				netdev_err(ndev, "cannot allocate skb\n");
219 			/* Return ownership to EMAC */
220 			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
221 			stats->rx_errors++;
222 			stats->rx_dropped++;
223 			continue;
224 		}
225 
226 		addr = dma_map_single(&ndev->dev, (void *)skb->data,
227 				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
228 		if (dma_mapping_error(&ndev->dev, addr)) {
229 			if (net_ratelimit())
230 				netdev_err(ndev, "cannot map dma buffer\n");
231 			dev_kfree_skb(skb);
232 			/* Return ownership to EMAC */
233 			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
234 			stats->rx_errors++;
235 			stats->rx_dropped++;
236 			continue;
237 		}
238 
239 		/* unmap previosly mapped skb */
240 		dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
241 				 dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
242 
243 		pktlen = info & LEN_MASK;
244 		stats->rx_packets++;
245 		stats->rx_bytes += pktlen;
246 		skb_put(rx_buff->skb, pktlen);
247 		rx_buff->skb->dev = ndev;
248 		rx_buff->skb->protocol = eth_type_trans(rx_buff->skb, ndev);
249 
250 		netif_receive_skb(rx_buff->skb);
251 
252 		rx_buff->skb = skb;
253 		dma_unmap_addr_set(rx_buff, addr, addr);
254 		dma_unmap_len_set(rx_buff, len, EMAC_BUFFER_SIZE);
255 
256 		rxbd->data = cpu_to_le32(addr);
257 
258 		/* Make sure pointer to data buffer is set */
259 		wmb();
260 
261 		/* Return ownership to EMAC */
262 		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
263 	}
264 
265 	return work_done;
266 }
267 
268 /**
269  * arc_emac_rx_miss_handle - handle R_MISS register
270  * @ndev:	Pointer to the net_device structure.
271  */
272 static void arc_emac_rx_miss_handle(struct net_device *ndev)
273 {
274 	struct arc_emac_priv *priv = netdev_priv(ndev);
275 	struct net_device_stats *stats = &ndev->stats;
276 	unsigned int miss;
277 
278 	miss = arc_reg_get(priv, R_MISS);
279 	if (miss) {
280 		stats->rx_errors += miss;
281 		stats->rx_missed_errors += miss;
282 		priv->rx_missed_errors += miss;
283 	}
284 }
285 
286 /**
287  * arc_emac_rx_stall_check - check RX stall
288  * @ndev:	Pointer to the net_device structure.
289  * @budget:	How many BDs requested to process on 1 call.
290  * @work_done:	How many BDs processed
291  *
292  * Under certain conditions EMAC stop reception of incoming packets and
293  * continuously increment R_MISS register instead of saving data into
294  * provided buffer. This function detect that condition and restart
295  * EMAC.
296  */
297 static void arc_emac_rx_stall_check(struct net_device *ndev,
298 				    int budget, unsigned int work_done)
299 {
300 	struct arc_emac_priv *priv = netdev_priv(ndev);
301 	struct arc_emac_bd *rxbd;
302 
303 	if (work_done)
304 		priv->rx_missed_errors = 0;
305 
306 	if (priv->rx_missed_errors && budget) {
307 		rxbd = &priv->rxbd[priv->last_rx_bd];
308 		if (le32_to_cpu(rxbd->info) & FOR_EMAC) {
309 			arc_emac_restart(ndev);
310 			priv->rx_missed_errors = 0;
311 		}
312 	}
313 }
314 
315 /**
316  * arc_emac_poll - NAPI poll handler.
317  * @napi:	Pointer to napi_struct structure.
318  * @budget:	How many BDs to process on 1 call.
319  *
320  * returns:	Number of processed BDs
321  */
322 static int arc_emac_poll(struct napi_struct *napi, int budget)
323 {
324 	struct net_device *ndev = napi->dev;
325 	struct arc_emac_priv *priv = netdev_priv(ndev);
326 	unsigned int work_done;
327 
328 	arc_emac_tx_clean(ndev);
329 	arc_emac_rx_miss_handle(ndev);
330 
331 	work_done = arc_emac_rx(ndev, budget);
332 	if (work_done < budget) {
333 		napi_complete_done(napi, work_done);
334 		arc_reg_or(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);
335 	}
336 
337 	arc_emac_rx_stall_check(ndev, budget, work_done);
338 
339 	return work_done;
340 }
341 
342 /**
343  * arc_emac_intr - Global interrupt handler for EMAC.
344  * @irq:		irq number.
345  * @dev_instance:	device instance.
346  *
347  * returns: IRQ_HANDLED for all cases.
348  *
349  * ARC EMAC has only 1 interrupt line, and depending on bits raised in
350  * STATUS register we may tell what is a reason for interrupt to fire.
351  */
352 static irqreturn_t arc_emac_intr(int irq, void *dev_instance)
353 {
354 	struct net_device *ndev = dev_instance;
355 	struct arc_emac_priv *priv = netdev_priv(ndev);
356 	struct net_device_stats *stats = &ndev->stats;
357 	unsigned int status;
358 
359 	status = arc_reg_get(priv, R_STATUS);
360 	status &= ~MDIO_MASK;
361 
362 	/* Reset all flags except "MDIO complete" */
363 	arc_reg_set(priv, R_STATUS, status);
364 
365 	if (status & (RXINT_MASK | TXINT_MASK)) {
366 		if (likely(napi_schedule_prep(&priv->napi))) {
367 			arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);
368 			__napi_schedule(&priv->napi);
369 		}
370 	}
371 
372 	if (status & ERR_MASK) {
373 		/* MSER/RXCR/RXFR/RXFL interrupt fires on corresponding
374 		 * 8-bit error counter overrun.
375 		 */
376 
377 		if (status & MSER_MASK) {
378 			stats->rx_missed_errors += 0x100;
379 			stats->rx_errors += 0x100;
380 			priv->rx_missed_errors += 0x100;
381 			napi_schedule(&priv->napi);
382 		}
383 
384 		if (status & RXCR_MASK) {
385 			stats->rx_crc_errors += 0x100;
386 			stats->rx_errors += 0x100;
387 		}
388 
389 		if (status & RXFR_MASK) {
390 			stats->rx_frame_errors += 0x100;
391 			stats->rx_errors += 0x100;
392 		}
393 
394 		if (status & RXFL_MASK) {
395 			stats->rx_over_errors += 0x100;
396 			stats->rx_errors += 0x100;
397 		}
398 	}
399 
400 	return IRQ_HANDLED;
401 }
402 
403 #ifdef CONFIG_NET_POLL_CONTROLLER
404 static void arc_emac_poll_controller(struct net_device *dev)
405 {
406 	disable_irq(dev->irq);
407 	arc_emac_intr(dev->irq, dev);
408 	enable_irq(dev->irq);
409 }
410 #endif
411 
412 /**
413  * arc_emac_open - Open the network device.
414  * @ndev:	Pointer to the network device.
415  *
416  * returns: 0, on success or non-zero error value on failure.
417  *
418  * This function sets the MAC address, requests and enables an IRQ
419  * for the EMAC device and starts the Tx queue.
420  * It also connects to the phy device.
421  */
422 static int arc_emac_open(struct net_device *ndev)
423 {
424 	struct arc_emac_priv *priv = netdev_priv(ndev);
425 	struct phy_device *phy_dev = ndev->phydev;
426 	int i;
427 
428 	phy_dev->autoneg = AUTONEG_ENABLE;
429 	phy_dev->speed = 0;
430 	phy_dev->duplex = 0;
431 	linkmode_and(phy_dev->advertising, phy_dev->advertising,
432 		     phy_dev->supported);
433 
434 	priv->last_rx_bd = 0;
435 
436 	/* Allocate and set buffers for Rx BD's */
437 	for (i = 0; i < RX_BD_NUM; i++) {
438 		dma_addr_t addr;
439 		unsigned int *last_rx_bd = &priv->last_rx_bd;
440 		struct arc_emac_bd *rxbd = &priv->rxbd[*last_rx_bd];
441 		struct buffer_state *rx_buff = &priv->rx_buff[*last_rx_bd];
442 
443 		rx_buff->skb = netdev_alloc_skb_ip_align(ndev,
444 							 EMAC_BUFFER_SIZE);
445 		if (unlikely(!rx_buff->skb))
446 			return -ENOMEM;
447 
448 		addr = dma_map_single(&ndev->dev, (void *)rx_buff->skb->data,
449 				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
450 		if (dma_mapping_error(&ndev->dev, addr)) {
451 			netdev_err(ndev, "cannot dma map\n");
452 			dev_kfree_skb(rx_buff->skb);
453 			return -ENOMEM;
454 		}
455 		dma_unmap_addr_set(rx_buff, addr, addr);
456 		dma_unmap_len_set(rx_buff, len, EMAC_BUFFER_SIZE);
457 
458 		rxbd->data = cpu_to_le32(addr);
459 
460 		/* Make sure pointer to data buffer is set */
461 		wmb();
462 
463 		/* Return ownership to EMAC */
464 		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
465 
466 		*last_rx_bd = (*last_rx_bd + 1) % RX_BD_NUM;
467 	}
468 
469 	priv->txbd_curr = 0;
470 	priv->txbd_dirty = 0;
471 
472 	/* Clean Tx BD's */
473 	memset(priv->txbd, 0, TX_RING_SZ);
474 
475 	/* Initialize logical address filter */
476 	arc_reg_set(priv, R_LAFL, 0);
477 	arc_reg_set(priv, R_LAFH, 0);
478 
479 	/* Set BD ring pointers for device side */
480 	arc_reg_set(priv, R_RX_RING, (unsigned int)priv->rxbd_dma);
481 	arc_reg_set(priv, R_TX_RING, (unsigned int)priv->txbd_dma);
482 
483 	/* Enable interrupts */
484 	arc_reg_set(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
485 
486 	/* Set CONTROL */
487 	arc_reg_set(priv, R_CTRL,
488 		    (RX_BD_NUM << 24) |	/* RX BD table length */
489 		    (TX_BD_NUM << 16) |	/* TX BD table length */
490 		    TXRN_MASK | RXRN_MASK);
491 
492 	napi_enable(&priv->napi);
493 
494 	/* Enable EMAC */
495 	arc_reg_or(priv, R_CTRL, EN_MASK);
496 
497 	phy_start(ndev->phydev);
498 
499 	netif_start_queue(ndev);
500 
501 	return 0;
502 }
503 
504 /**
505  * arc_emac_set_rx_mode - Change the receive filtering mode.
506  * @ndev:	Pointer to the network device.
507  *
508  * This function enables/disables promiscuous or all-multicast mode
509  * and updates the multicast filtering list of the network device.
510  */
511 static void arc_emac_set_rx_mode(struct net_device *ndev)
512 {
513 	struct arc_emac_priv *priv = netdev_priv(ndev);
514 
515 	if (ndev->flags & IFF_PROMISC) {
516 		arc_reg_or(priv, R_CTRL, PROM_MASK);
517 	} else {
518 		arc_reg_clr(priv, R_CTRL, PROM_MASK);
519 
520 		if (ndev->flags & IFF_ALLMULTI) {
521 			arc_reg_set(priv, R_LAFL, ~0);
522 			arc_reg_set(priv, R_LAFH, ~0);
523 		} else if (ndev->flags & IFF_MULTICAST) {
524 			struct netdev_hw_addr *ha;
525 			unsigned int filter[2] = { 0, 0 };
526 			int bit;
527 
528 			netdev_for_each_mc_addr(ha, ndev) {
529 				bit = ether_crc_le(ETH_ALEN, ha->addr) >> 26;
530 				filter[bit >> 5] |= 1 << (bit & 31);
531 			}
532 
533 			arc_reg_set(priv, R_LAFL, filter[0]);
534 			arc_reg_set(priv, R_LAFH, filter[1]);
535 		} else {
536 			arc_reg_set(priv, R_LAFL, 0);
537 			arc_reg_set(priv, R_LAFH, 0);
538 		}
539 	}
540 }
541 
542 /**
543  * arc_free_tx_queue - free skb from tx queue
544  * @ndev:	Pointer to the network device.
545  *
546  * This function must be called while EMAC disable
547  */
548 static void arc_free_tx_queue(struct net_device *ndev)
549 {
550 	struct arc_emac_priv *priv = netdev_priv(ndev);
551 	unsigned int i;
552 
553 	for (i = 0; i < TX_BD_NUM; i++) {
554 		struct arc_emac_bd *txbd = &priv->txbd[i];
555 		struct buffer_state *tx_buff = &priv->tx_buff[i];
556 
557 		if (tx_buff->skb) {
558 			dma_unmap_single(&ndev->dev,
559 					 dma_unmap_addr(tx_buff, addr),
560 					 dma_unmap_len(tx_buff, len),
561 					 DMA_TO_DEVICE);
562 
563 			/* return the sk_buff to system */
564 			dev_kfree_skb_irq(tx_buff->skb);
565 		}
566 
567 		txbd->info = 0;
568 		txbd->data = 0;
569 		tx_buff->skb = NULL;
570 	}
571 }
572 
573 /**
574  * arc_free_rx_queue - free skb from rx queue
575  * @ndev:	Pointer to the network device.
576  *
577  * This function must be called while EMAC disable
578  */
579 static void arc_free_rx_queue(struct net_device *ndev)
580 {
581 	struct arc_emac_priv *priv = netdev_priv(ndev);
582 	unsigned int i;
583 
584 	for (i = 0; i < RX_BD_NUM; i++) {
585 		struct arc_emac_bd *rxbd = &priv->rxbd[i];
586 		struct buffer_state *rx_buff = &priv->rx_buff[i];
587 
588 		if (rx_buff->skb) {
589 			dma_unmap_single(&ndev->dev,
590 					 dma_unmap_addr(rx_buff, addr),
591 					 dma_unmap_len(rx_buff, len),
592 					 DMA_FROM_DEVICE);
593 
594 			/* return the sk_buff to system */
595 			dev_kfree_skb_irq(rx_buff->skb);
596 		}
597 
598 		rxbd->info = 0;
599 		rxbd->data = 0;
600 		rx_buff->skb = NULL;
601 	}
602 }
603 
604 /**
605  * arc_emac_stop - Close the network device.
606  * @ndev:	Pointer to the network device.
607  *
608  * This function stops the Tx queue, disables interrupts and frees the IRQ for
609  * the EMAC device.
610  * It also disconnects the PHY device associated with the EMAC device.
611  */
612 static int arc_emac_stop(struct net_device *ndev)
613 {
614 	struct arc_emac_priv *priv = netdev_priv(ndev);
615 
616 	napi_disable(&priv->napi);
617 	netif_stop_queue(ndev);
618 
619 	phy_stop(ndev->phydev);
620 
621 	/* Disable interrupts */
622 	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
623 
624 	/* Disable EMAC */
625 	arc_reg_clr(priv, R_CTRL, EN_MASK);
626 
627 	/* Return the sk_buff to system */
628 	arc_free_tx_queue(ndev);
629 	arc_free_rx_queue(ndev);
630 
631 	return 0;
632 }
633 
634 /**
635  * arc_emac_stats - Get system network statistics.
636  * @ndev:	Pointer to net_device structure.
637  *
638  * Returns the address of the device statistics structure.
639  * Statistics are updated in interrupt handler.
640  */
641 static struct net_device_stats *arc_emac_stats(struct net_device *ndev)
642 {
643 	struct arc_emac_priv *priv = netdev_priv(ndev);
644 	struct net_device_stats *stats = &ndev->stats;
645 	unsigned long miss, rxerr;
646 	u8 rxcrc, rxfram, rxoflow;
647 
648 	rxerr = arc_reg_get(priv, R_RXERR);
649 	miss = arc_reg_get(priv, R_MISS);
650 
651 	rxcrc = rxerr;
652 	rxfram = rxerr >> 8;
653 	rxoflow = rxerr >> 16;
654 
655 	stats->rx_errors += miss;
656 	stats->rx_errors += rxcrc + rxfram + rxoflow;
657 
658 	stats->rx_over_errors += rxoflow;
659 	stats->rx_frame_errors += rxfram;
660 	stats->rx_crc_errors += rxcrc;
661 	stats->rx_missed_errors += miss;
662 
663 	return stats;
664 }
665 
666 /**
667  * arc_emac_tx - Starts the data transmission.
668  * @skb:	sk_buff pointer that contains data to be Transmitted.
669  * @ndev:	Pointer to net_device structure.
670  *
671  * returns: NETDEV_TX_OK, on success
672  *		NETDEV_TX_BUSY, if any of the descriptors are not free.
673  *
674  * This function is invoked from upper layers to initiate transmission.
675  */
676 static netdev_tx_t arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
677 {
678 	struct arc_emac_priv *priv = netdev_priv(ndev);
679 	unsigned int len, *txbd_curr = &priv->txbd_curr;
680 	struct net_device_stats *stats = &ndev->stats;
681 	__le32 *info = &priv->txbd[*txbd_curr].info;
682 	dma_addr_t addr;
683 
684 	if (skb_padto(skb, ETH_ZLEN))
685 		return NETDEV_TX_OK;
686 
687 	len = max_t(unsigned int, ETH_ZLEN, skb->len);
688 
689 	if (unlikely(!arc_emac_tx_avail(priv))) {
690 		netif_stop_queue(ndev);
691 		netdev_err(ndev, "BUG! Tx Ring full when queue awake!\n");
692 		return NETDEV_TX_BUSY;
693 	}
694 
695 	addr = dma_map_single(&ndev->dev, (void *)skb->data, len,
696 			      DMA_TO_DEVICE);
697 
698 	if (unlikely(dma_mapping_error(&ndev->dev, addr))) {
699 		stats->tx_dropped++;
700 		stats->tx_errors++;
701 		dev_kfree_skb_any(skb);
702 		return NETDEV_TX_OK;
703 	}
704 	dma_unmap_addr_set(&priv->tx_buff[*txbd_curr], addr, addr);
705 	dma_unmap_len_set(&priv->tx_buff[*txbd_curr], len, len);
706 
707 	priv->txbd[*txbd_curr].data = cpu_to_le32(addr);
708 
709 	/* Make sure pointer to data buffer is set */
710 	wmb();
711 
712 	skb_tx_timestamp(skb);
713 
714 	*info = cpu_to_le32(FOR_EMAC | FIRST_OR_LAST_MASK | len);
715 
716 	/* Make sure info word is set */
717 	wmb();
718 
719 	priv->tx_buff[*txbd_curr].skb = skb;
720 
721 	/* Increment index to point to the next BD */
722 	*txbd_curr = (*txbd_curr + 1) % TX_BD_NUM;
723 
724 	/* Ensure that tx_clean() sees the new txbd_curr before
725 	 * checking the queue status. This prevents an unneeded wake
726 	 * of the queue in tx_clean().
727 	 */
728 	smp_mb();
729 
730 	if (!arc_emac_tx_avail(priv)) {
731 		netif_stop_queue(ndev);
732 		/* Refresh tx_dirty */
733 		smp_mb();
734 		if (arc_emac_tx_avail(priv))
735 			netif_start_queue(ndev);
736 	}
737 
738 	arc_reg_set(priv, R_STATUS, TXPL_MASK);
739 
740 	return NETDEV_TX_OK;
741 }
742 
743 static void arc_emac_set_address_internal(struct net_device *ndev)
744 {
745 	struct arc_emac_priv *priv = netdev_priv(ndev);
746 	unsigned int addr_low, addr_hi;
747 
748 	addr_low = le32_to_cpu(*(__le32 *)&ndev->dev_addr[0]);
749 	addr_hi = le16_to_cpu(*(__le16 *)&ndev->dev_addr[4]);
750 
751 	arc_reg_set(priv, R_ADDRL, addr_low);
752 	arc_reg_set(priv, R_ADDRH, addr_hi);
753 }
754 
755 /**
756  * arc_emac_set_address - Set the MAC address for this device.
757  * @ndev:	Pointer to net_device structure.
758  * @p:		6 byte Address to be written as MAC address.
759  *
760  * This function copies the HW address from the sockaddr structure to the
761  * net_device structure and updates the address in HW.
762  *
763  * returns:	-EBUSY if the net device is busy or 0 if the address is set
764  *		successfully.
765  */
766 static int arc_emac_set_address(struct net_device *ndev, void *p)
767 {
768 	struct sockaddr *addr = p;
769 
770 	if (netif_running(ndev))
771 		return -EBUSY;
772 
773 	if (!is_valid_ether_addr(addr->sa_data))
774 		return -EADDRNOTAVAIL;
775 
776 	eth_hw_addr_set(ndev, addr->sa_data);
777 
778 	arc_emac_set_address_internal(ndev);
779 
780 	return 0;
781 }
782 
783 /**
784  * arc_emac_restart - Restart EMAC
785  * @ndev:	Pointer to net_device structure.
786  *
787  * This function do hardware reset of EMAC in order to restore
788  * network packets reception.
789  */
790 static void arc_emac_restart(struct net_device *ndev)
791 {
792 	struct arc_emac_priv *priv = netdev_priv(ndev);
793 	struct net_device_stats *stats = &ndev->stats;
794 	int i;
795 
796 	if (net_ratelimit())
797 		netdev_warn(ndev, "restarting stalled EMAC\n");
798 
799 	netif_stop_queue(ndev);
800 
801 	/* Disable interrupts */
802 	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
803 
804 	/* Disable EMAC */
805 	arc_reg_clr(priv, R_CTRL, EN_MASK);
806 
807 	/* Return the sk_buff to system */
808 	arc_free_tx_queue(ndev);
809 
810 	/* Clean Tx BD's */
811 	priv->txbd_curr = 0;
812 	priv->txbd_dirty = 0;
813 	memset(priv->txbd, 0, TX_RING_SZ);
814 
815 	for (i = 0; i < RX_BD_NUM; i++) {
816 		struct arc_emac_bd *rxbd = &priv->rxbd[i];
817 		unsigned int info = le32_to_cpu(rxbd->info);
818 
819 		if (!(info & FOR_EMAC)) {
820 			stats->rx_errors++;
821 			stats->rx_dropped++;
822 		}
823 		/* Return ownership to EMAC */
824 		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
825 	}
826 	priv->last_rx_bd = 0;
827 
828 	/* Make sure info is visible to EMAC before enable */
829 	wmb();
830 
831 	/* Enable interrupts */
832 	arc_reg_set(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
833 
834 	/* Enable EMAC */
835 	arc_reg_or(priv, R_CTRL, EN_MASK);
836 
837 	netif_start_queue(ndev);
838 }
839 
840 static const struct net_device_ops arc_emac_netdev_ops = {
841 	.ndo_open		= arc_emac_open,
842 	.ndo_stop		= arc_emac_stop,
843 	.ndo_start_xmit		= arc_emac_tx,
844 	.ndo_set_mac_address	= arc_emac_set_address,
845 	.ndo_get_stats		= arc_emac_stats,
846 	.ndo_set_rx_mode	= arc_emac_set_rx_mode,
847 	.ndo_eth_ioctl		= phy_do_ioctl_running,
848 #ifdef CONFIG_NET_POLL_CONTROLLER
849 	.ndo_poll_controller	= arc_emac_poll_controller,
850 #endif
851 };
852 
853 int arc_emac_probe(struct net_device *ndev, int interface)
854 {
855 	struct device *dev = ndev->dev.parent;
856 	struct resource res_regs;
857 	struct device_node *phy_node;
858 	struct phy_device *phydev = NULL;
859 	struct arc_emac_priv *priv;
860 	unsigned int id, clock_frequency, irq;
861 	int err;
862 
863 	/* Get PHY from device tree */
864 	phy_node = of_parse_phandle(dev->of_node, "phy", 0);
865 	if (!phy_node) {
866 		dev_err(dev, "failed to retrieve phy description from device tree\n");
867 		return -ENODEV;
868 	}
869 
870 	/* Get EMAC registers base address from device tree */
871 	err = of_address_to_resource(dev->of_node, 0, &res_regs);
872 	if (err) {
873 		dev_err(dev, "failed to retrieve registers base from device tree\n");
874 		err = -ENODEV;
875 		goto out_put_node;
876 	}
877 
878 	/* Get IRQ from device tree */
879 	irq = irq_of_parse_and_map(dev->of_node, 0);
880 	if (!irq) {
881 		dev_err(dev, "failed to retrieve <irq> value from device tree\n");
882 		err = -ENODEV;
883 		goto out_put_node;
884 	}
885 
886 	ndev->netdev_ops = &arc_emac_netdev_ops;
887 	ndev->ethtool_ops = &arc_emac_ethtool_ops;
888 	ndev->watchdog_timeo = TX_TIMEOUT;
889 
890 	priv = netdev_priv(ndev);
891 	priv->dev = dev;
892 
893 	priv->regs = devm_ioremap_resource(dev, &res_regs);
894 	if (IS_ERR(priv->regs)) {
895 		err = PTR_ERR(priv->regs);
896 		goto out_put_node;
897 	}
898 
899 	dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs);
900 
901 	if (priv->clk) {
902 		err = clk_prepare_enable(priv->clk);
903 		if (err) {
904 			dev_err(dev, "failed to enable clock\n");
905 			goto out_put_node;
906 		}
907 
908 		clock_frequency = clk_get_rate(priv->clk);
909 	} else {
910 		/* Get CPU clock frequency from device tree */
911 		if (of_property_read_u32(dev->of_node, "clock-frequency",
912 					 &clock_frequency)) {
913 			dev_err(dev, "failed to retrieve <clock-frequency> from device tree\n");
914 			err = -EINVAL;
915 			goto out_put_node;
916 		}
917 	}
918 
919 	id = arc_reg_get(priv, R_ID);
920 
921 	/* Check for EMAC revision 5 or 7, magic number */
922 	if (!(id == 0x0005fd02 || id == 0x0007fd02)) {
923 		dev_err(dev, "ARC EMAC not detected, id=0x%x\n", id);
924 		err = -ENODEV;
925 		goto out_clken;
926 	}
927 	dev_info(dev, "ARC EMAC detected with id: 0x%x\n", id);
928 
929 	/* Set poll rate so that it polls every 1 ms */
930 	arc_reg_set(priv, R_POLLRATE, clock_frequency / 1000000);
931 
932 	ndev->irq = irq;
933 	dev_info(dev, "IRQ is %d\n", ndev->irq);
934 
935 	/* Register interrupt handler for device */
936 	err = devm_request_irq(dev, ndev->irq, arc_emac_intr, 0,
937 			       ndev->name, ndev);
938 	if (err) {
939 		dev_err(dev, "could not allocate IRQ\n");
940 		goto out_clken;
941 	}
942 
943 	/* Get MAC address from device tree */
944 	err = of_get_ethdev_address(dev->of_node, ndev);
945 	if (err)
946 		eth_hw_addr_random(ndev);
947 
948 	arc_emac_set_address_internal(ndev);
949 	dev_info(dev, "MAC address is now %pM\n", ndev->dev_addr);
950 
951 	/* Do 1 allocation instead of 2 separate ones for Rx and Tx BD rings */
952 	priv->rxbd = dmam_alloc_coherent(dev, RX_RING_SZ + TX_RING_SZ,
953 					 &priv->rxbd_dma, GFP_KERNEL);
954 
955 	if (!priv->rxbd) {
956 		dev_err(dev, "failed to allocate data buffers\n");
957 		err = -ENOMEM;
958 		goto out_clken;
959 	}
960 
961 	priv->txbd = priv->rxbd + RX_BD_NUM;
962 
963 	priv->txbd_dma = priv->rxbd_dma + RX_RING_SZ;
964 	dev_dbg(dev, "EMAC Device addr: Rx Ring [0x%x], Tx Ring[%x]\n",
965 		(unsigned int)priv->rxbd_dma, (unsigned int)priv->txbd_dma);
966 
967 	err = arc_mdio_probe(priv);
968 	if (err) {
969 		dev_err(dev, "failed to probe MII bus\n");
970 		goto out_clken;
971 	}
972 
973 	phydev = of_phy_connect(ndev, phy_node, arc_emac_adjust_link, 0,
974 				interface);
975 	if (!phydev) {
976 		dev_err(dev, "of_phy_connect() failed\n");
977 		err = -ENODEV;
978 		goto out_mdio;
979 	}
980 
981 	dev_info(dev, "connected to %s phy with id 0x%x\n",
982 		 phydev->drv->name, phydev->phy_id);
983 
984 	netif_napi_add_weight(ndev, &priv->napi, arc_emac_poll,
985 			      ARC_EMAC_NAPI_WEIGHT);
986 
987 	err = register_netdev(ndev);
988 	if (err) {
989 		dev_err(dev, "failed to register network device\n");
990 		goto out_netif_api;
991 	}
992 
993 	of_node_put(phy_node);
994 	return 0;
995 
996 out_netif_api:
997 	netif_napi_del(&priv->napi);
998 	phy_disconnect(phydev);
999 out_mdio:
1000 	arc_mdio_remove(priv);
1001 out_clken:
1002 	if (priv->clk)
1003 		clk_disable_unprepare(priv->clk);
1004 out_put_node:
1005 	of_node_put(phy_node);
1006 
1007 	return err;
1008 }
1009 EXPORT_SYMBOL_GPL(arc_emac_probe);
1010 
1011 int arc_emac_remove(struct net_device *ndev)
1012 {
1013 	struct arc_emac_priv *priv = netdev_priv(ndev);
1014 
1015 	phy_disconnect(ndev->phydev);
1016 	arc_mdio_remove(priv);
1017 	unregister_netdev(ndev);
1018 	netif_napi_del(&priv->napi);
1019 
1020 	if (!IS_ERR(priv->clk))
1021 		clk_disable_unprepare(priv->clk);
1022 
1023 	return 0;
1024 }
1025 EXPORT_SYMBOL_GPL(arc_emac_remove);
1026 
1027 MODULE_AUTHOR("Alexey Brodkin <abrodkin@synopsys.com>");
1028 MODULE_DESCRIPTION("ARC EMAC driver");
1029 MODULE_LICENSE("GPL");
1030