xref: /linux/drivers/net/ethernet/ezchip/nps_enet.c (revision 7f71507851fc7764b36a3221839607d3a45c2025)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright(c) 2015 EZchip Technologies.
4  */
5 
6 #include <linux/module.h>
7 #include <linux/etherdevice.h>
8 #include <linux/interrupt.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/of_net.h>
11 #include <linux/platform_device.h>
12 #include "nps_enet.h"
13 
14 #define DRV_NAME			"nps_mgt_enet"
15 
16 static inline bool nps_enet_is_tx_pending(struct nps_enet_priv *priv)
17 {
18 	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
19 	u32 tx_ctrl_ct = (tx_ctrl_value & TX_CTL_CT_MASK) >> TX_CTL_CT_SHIFT;
20 
21 	return (!tx_ctrl_ct && priv->tx_skb);
22 }
23 
24 static void nps_enet_clean_rx_fifo(struct net_device *ndev, u32 frame_len)
25 {
26 	struct nps_enet_priv *priv = netdev_priv(ndev);
27 	u32 i, len = DIV_ROUND_UP(frame_len, sizeof(u32));
28 
29 	/* Empty Rx FIFO buffer by reading all words */
30 	for (i = 0; i < len; i++)
31 		nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
32 }
33 
34 static void nps_enet_read_rx_fifo(struct net_device *ndev,
35 				  unsigned char *dst, u32 length)
36 {
37 	struct nps_enet_priv *priv = netdev_priv(ndev);
38 	s32 i, last = length & (sizeof(u32) - 1);
39 	u32 *reg = (u32 *)dst, len = length / sizeof(u32);
40 	bool dst_is_aligned = IS_ALIGNED((unsigned long)dst, sizeof(u32));
41 
42 	/* In case dst is not aligned we need an intermediate buffer */
43 	if (dst_is_aligned) {
44 		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, reg, len);
45 		reg += len;
46 	} else { /* !dst_is_aligned */
47 		for (i = 0; i < len; i++, reg++) {
48 			u32 buf = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
49 
50 			put_unaligned_be32(buf, reg);
51 		}
52 	}
53 	/* copy last bytes (if any) */
54 	if (last) {
55 		u32 buf;
56 
57 		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, &buf, 1);
58 		memcpy((u8 *)reg, &buf, last);
59 	}
60 }
61 
62 static u32 nps_enet_rx_handler(struct net_device *ndev)
63 {
64 	u32 frame_len, err = 0;
65 	u32 work_done = 0;
66 	struct nps_enet_priv *priv = netdev_priv(ndev);
67 	struct sk_buff *skb;
68 	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
69 	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
70 	u32 rx_ctrl_er = (rx_ctrl_value & RX_CTL_ER_MASK) >> RX_CTL_ER_SHIFT;
71 	u32 rx_ctrl_crc = (rx_ctrl_value & RX_CTL_CRC_MASK) >> RX_CTL_CRC_SHIFT;
72 
73 	frame_len = (rx_ctrl_value & RX_CTL_NR_MASK) >> RX_CTL_NR_SHIFT;
74 
75 	/* Check if we got RX */
76 	if (!rx_ctrl_cr)
77 		return work_done;
78 
79 	/* If we got here there is a work for us */
80 	work_done++;
81 
82 	/* Check Rx error */
83 	if (rx_ctrl_er) {
84 		ndev->stats.rx_errors++;
85 		err = 1;
86 	}
87 
88 	/* Check Rx CRC error */
89 	if (rx_ctrl_crc) {
90 		ndev->stats.rx_crc_errors++;
91 		ndev->stats.rx_dropped++;
92 		err = 1;
93 	}
94 
95 	/* Check Frame length Min 64b */
96 	if (unlikely(frame_len < ETH_ZLEN)) {
97 		ndev->stats.rx_length_errors++;
98 		ndev->stats.rx_dropped++;
99 		err = 1;
100 	}
101 
102 	if (err)
103 		goto rx_irq_clean;
104 
105 	/* Skb allocation */
106 	skb = netdev_alloc_skb_ip_align(ndev, frame_len);
107 	if (unlikely(!skb)) {
108 		ndev->stats.rx_errors++;
109 		ndev->stats.rx_dropped++;
110 		goto rx_irq_clean;
111 	}
112 
113 	/* Copy frame from Rx fifo into the skb */
114 	nps_enet_read_rx_fifo(ndev, skb->data, frame_len);
115 
116 	skb_put(skb, frame_len);
117 	skb->protocol = eth_type_trans(skb, ndev);
118 	skb->ip_summed = CHECKSUM_UNNECESSARY;
119 
120 	ndev->stats.rx_packets++;
121 	ndev->stats.rx_bytes += frame_len;
122 	netif_receive_skb(skb);
123 
124 	goto rx_irq_frame_done;
125 
126 rx_irq_clean:
127 	/* Clean Rx fifo */
128 	nps_enet_clean_rx_fifo(ndev, frame_len);
129 
130 rx_irq_frame_done:
131 	/* Ack Rx ctrl register */
132 	nps_enet_reg_set(priv, NPS_ENET_REG_RX_CTL, 0);
133 
134 	return work_done;
135 }
136 
137 static void nps_enet_tx_handler(struct net_device *ndev)
138 {
139 	struct nps_enet_priv *priv = netdev_priv(ndev);
140 	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
141 	u32 tx_ctrl_et = (tx_ctrl_value & TX_CTL_ET_MASK) >> TX_CTL_ET_SHIFT;
142 	u32 tx_ctrl_nt = (tx_ctrl_value & TX_CTL_NT_MASK) >> TX_CTL_NT_SHIFT;
143 
144 	/* Check if we got TX */
145 	if (!nps_enet_is_tx_pending(priv))
146 		return;
147 
148 	/* Ack Tx ctrl register */
149 	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, 0);
150 
151 	/* Check Tx transmit error */
152 	if (unlikely(tx_ctrl_et)) {
153 		ndev->stats.tx_errors++;
154 	} else {
155 		ndev->stats.tx_packets++;
156 		ndev->stats.tx_bytes += tx_ctrl_nt;
157 	}
158 
159 	dev_kfree_skb(priv->tx_skb);
160 	priv->tx_skb = NULL;
161 
162 	if (netif_queue_stopped(ndev))
163 		netif_wake_queue(ndev);
164 }
165 
166 /**
167  * nps_enet_poll - NAPI poll handler.
168  * @napi:       Pointer to napi_struct structure.
169  * @budget:     How many frames to process on one call.
170  *
171  * returns:     Number of processed frames
172  */
173 static int nps_enet_poll(struct napi_struct *napi, int budget)
174 {
175 	struct net_device *ndev = napi->dev;
176 	struct nps_enet_priv *priv = netdev_priv(ndev);
177 	u32 work_done;
178 
179 	nps_enet_tx_handler(ndev);
180 	work_done = nps_enet_rx_handler(ndev);
181 	if ((work_done < budget) && napi_complete_done(napi, work_done)) {
182 		u32 buf_int_enable_value = 0;
183 
184 		/* set tx_done and rx_rdy bits */
185 		buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
186 		buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
187 
188 		nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
189 				 buf_int_enable_value);
190 
191 		/* in case we will get a tx interrupt while interrupts
192 		 * are masked, we will lose it since the tx is edge interrupt.
193 		 * specifically, while executing the code section above,
194 		 * between nps_enet_tx_handler and the interrupts enable, all
195 		 * tx requests will be stuck until we will get an rx interrupt.
196 		 * the two code lines below will solve this situation by
197 		 * re-adding ourselves to the poll list.
198 		 */
199 		if (nps_enet_is_tx_pending(priv)) {
200 			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
201 			napi_schedule(napi);
202 		}
203 	}
204 
205 	return work_done;
206 }
207 
208 /**
209  * nps_enet_irq_handler - Global interrupt handler for ENET.
210  * @irq:                irq number.
211  * @dev_instance:       device instance.
212  *
213  * returns: IRQ_HANDLED for all cases.
214  *
215  * EZchip ENET has 2 interrupt causes, and depending on bits raised in
216  * CTRL registers we may tell what is a reason for interrupt to fire up.
217  * We got one for RX and the other for TX (completion).
218  */
219 static irqreturn_t nps_enet_irq_handler(s32 irq, void *dev_instance)
220 {
221 	struct net_device *ndev = dev_instance;
222 	struct nps_enet_priv *priv = netdev_priv(ndev);
223 	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
224 	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
225 
226 	if (nps_enet_is_tx_pending(priv) || rx_ctrl_cr)
227 		if (likely(napi_schedule_prep(&priv->napi))) {
228 			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
229 			__napi_schedule(&priv->napi);
230 		}
231 
232 	return IRQ_HANDLED;
233 }
234 
235 static void nps_enet_set_hw_mac_address(struct net_device *ndev)
236 {
237 	struct nps_enet_priv *priv = netdev_priv(ndev);
238 	u32 ge_mac_cfg_1_value = 0;
239 	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
240 
241 	/* set MAC address in HW */
242 	ge_mac_cfg_1_value |= ndev->dev_addr[0] << CFG_1_OCTET_0_SHIFT;
243 	ge_mac_cfg_1_value |= ndev->dev_addr[1] << CFG_1_OCTET_1_SHIFT;
244 	ge_mac_cfg_1_value |= ndev->dev_addr[2] << CFG_1_OCTET_2_SHIFT;
245 	ge_mac_cfg_1_value |= ndev->dev_addr[3] << CFG_1_OCTET_3_SHIFT;
246 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_4_MASK)
247 		 | ndev->dev_addr[4] << CFG_2_OCTET_4_SHIFT;
248 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_5_MASK)
249 		 | ndev->dev_addr[5] << CFG_2_OCTET_5_SHIFT;
250 
251 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_1,
252 			 ge_mac_cfg_1_value);
253 
254 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
255 			 *ge_mac_cfg_2_value);
256 }
257 
258 /**
259  * nps_enet_hw_reset - Reset the network device.
260  * @ndev:       Pointer to the network device.
261  *
262  * This function reset the PCS and TX fifo.
263  * The programming model is to set the relevant reset bits
264  * wait for some time for this to propagate and then unset
265  * the reset bits. This way we ensure that reset procedure
266  * is done successfully by device.
267  */
268 static void nps_enet_hw_reset(struct net_device *ndev)
269 {
270 	struct nps_enet_priv *priv = netdev_priv(ndev);
271 	u32 ge_rst_value = 0, phase_fifo_ctl_value = 0;
272 
273 	/* Pcs reset sequence*/
274 	ge_rst_value |= NPS_ENET_ENABLE << RST_GMAC_0_SHIFT;
275 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
276 	usleep_range(10, 20);
277 	ge_rst_value = 0;
278 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
279 
280 	/* Tx fifo reset sequence */
281 	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_RST_SHIFT;
282 	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_INIT_SHIFT;
283 	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
284 			 phase_fifo_ctl_value);
285 	usleep_range(10, 20);
286 	phase_fifo_ctl_value = 0;
287 	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
288 			 phase_fifo_ctl_value);
289 }
290 
291 static void nps_enet_hw_enable_control(struct net_device *ndev)
292 {
293 	struct nps_enet_priv *priv = netdev_priv(ndev);
294 	u32 ge_mac_cfg_0_value = 0, buf_int_enable_value = 0;
295 	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
296 	u32 *ge_mac_cfg_3_value = &priv->ge_mac_cfg_3_value;
297 	s32 max_frame_length;
298 
299 	/* Enable Rx and Tx statistics */
300 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_STAT_EN_MASK)
301 		 | NPS_ENET_GE_MAC_CFG_2_STAT_EN << CFG_2_STAT_EN_SHIFT;
302 
303 	/* Discard packets with different MAC address */
304 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
305 		 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
306 
307 	/* Discard multicast packets */
308 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
309 		 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
310 
311 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
312 			 *ge_mac_cfg_2_value);
313 
314 	/* Discard Packets bigger than max frame length */
315 	max_frame_length = ETH_HLEN + ndev->mtu + ETH_FCS_LEN;
316 	if (max_frame_length <= NPS_ENET_MAX_FRAME_LENGTH) {
317 		*ge_mac_cfg_3_value =
318 			 (*ge_mac_cfg_3_value & ~CFG_3_MAX_LEN_MASK)
319 			 | max_frame_length << CFG_3_MAX_LEN_SHIFT;
320 	}
321 
322 	/* Enable interrupts */
323 	buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
324 	buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
325 	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
326 			 buf_int_enable_value);
327 
328 	/* Write device MAC address to HW */
329 	nps_enet_set_hw_mac_address(ndev);
330 
331 	/* Rx and Tx HW features */
332 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_PAD_EN_SHIFT;
333 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_CRC_EN_SHIFT;
334 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_CRC_STRIP_SHIFT;
335 
336 	/* IFG configuration */
337 	ge_mac_cfg_0_value |=
338 		 NPS_ENET_GE_MAC_CFG_0_RX_IFG << CFG_0_RX_IFG_SHIFT;
339 	ge_mac_cfg_0_value |=
340 		 NPS_ENET_GE_MAC_CFG_0_TX_IFG << CFG_0_TX_IFG_SHIFT;
341 
342 	/* preamble configuration */
343 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_PR_CHECK_EN_SHIFT;
344 	ge_mac_cfg_0_value |=
345 		 NPS_ENET_GE_MAC_CFG_0_TX_PR_LEN << CFG_0_TX_PR_LEN_SHIFT;
346 
347 	/* enable flow control frames */
348 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_FC_EN_SHIFT;
349 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_FC_EN_SHIFT;
350 	ge_mac_cfg_0_value |=
351 		 NPS_ENET_GE_MAC_CFG_0_TX_FC_RETR << CFG_0_TX_FC_RETR_SHIFT;
352 	*ge_mac_cfg_3_value = (*ge_mac_cfg_3_value & ~CFG_3_CF_DROP_MASK)
353 		 | NPS_ENET_ENABLE << CFG_3_CF_DROP_SHIFT;
354 
355 	/* Enable Rx and Tx */
356 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_EN_SHIFT;
357 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_EN_SHIFT;
358 
359 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_3,
360 			 *ge_mac_cfg_3_value);
361 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0,
362 			 ge_mac_cfg_0_value);
363 }
364 
365 static void nps_enet_hw_disable_control(struct net_device *ndev)
366 {
367 	struct nps_enet_priv *priv = netdev_priv(ndev);
368 
369 	/* Disable interrupts */
370 	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
371 
372 	/* Disable Rx and Tx */
373 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0, 0);
374 }
375 
376 static void nps_enet_send_frame(struct net_device *ndev,
377 				struct sk_buff *skb)
378 {
379 	struct nps_enet_priv *priv = netdev_priv(ndev);
380 	u32 tx_ctrl_value = 0;
381 	short length = skb->len;
382 	u32 i, len = DIV_ROUND_UP(length, sizeof(u32));
383 	u32 *src = (void *)skb->data;
384 	bool src_is_aligned = IS_ALIGNED((unsigned long)src, sizeof(u32));
385 
386 	/* In case src is not aligned we need an intermediate buffer */
387 	if (src_is_aligned)
388 		iowrite32_rep(priv->regs_base + NPS_ENET_REG_TX_BUF, src, len);
389 	else /* !src_is_aligned */
390 		for (i = 0; i < len; i++, src++)
391 			nps_enet_reg_set(priv, NPS_ENET_REG_TX_BUF,
392 					 get_unaligned_be32(src));
393 
394 	/* Write the length of the Frame */
395 	tx_ctrl_value |= length << TX_CTL_NT_SHIFT;
396 
397 	tx_ctrl_value |= NPS_ENET_ENABLE << TX_CTL_CT_SHIFT;
398 	/* Send Frame */
399 	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, tx_ctrl_value);
400 }
401 
402 /**
403  * nps_enet_set_mac_address - Set the MAC address for this device.
404  * @ndev:       Pointer to net_device structure.
405  * @p:          6 byte Address to be written as MAC address.
406  *
407  * This function copies the HW address from the sockaddr structure to the
408  * net_device structure and updates the address in HW.
409  *
410  * returns:     -EBUSY if the net device is busy or 0 if the address is set
411  *              successfully.
412  */
413 static s32 nps_enet_set_mac_address(struct net_device *ndev, void *p)
414 {
415 	struct sockaddr *addr = p;
416 	s32 res;
417 
418 	if (netif_running(ndev))
419 		return -EBUSY;
420 
421 	res = eth_mac_addr(ndev, p);
422 	if (!res) {
423 		eth_hw_addr_set(ndev, addr->sa_data);
424 		nps_enet_set_hw_mac_address(ndev);
425 	}
426 
427 	return res;
428 }
429 
430 /**
431  * nps_enet_set_rx_mode - Change the receive filtering mode.
432  * @ndev:       Pointer to the network device.
433  *
434  * This function enables/disables promiscuous mode
435  */
436 static void nps_enet_set_rx_mode(struct net_device *ndev)
437 {
438 	struct nps_enet_priv *priv = netdev_priv(ndev);
439 	u32 ge_mac_cfg_2_value = priv->ge_mac_cfg_2_value;
440 
441 	if (ndev->flags & IFF_PROMISC) {
442 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
443 			 | NPS_ENET_DISABLE << CFG_2_DISK_DA_SHIFT;
444 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
445 			 | NPS_ENET_DISABLE << CFG_2_DISK_MC_SHIFT;
446 
447 	} else {
448 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
449 			 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
450 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
451 			 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
452 	}
453 
454 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2, ge_mac_cfg_2_value);
455 }
456 
457 /**
458  * nps_enet_open - Open the network device.
459  * @ndev:       Pointer to the network device.
460  *
461  * returns: 0, on success or non-zero error value on failure.
462  *
463  * This function sets the MAC address, requests and enables an IRQ
464  * for the ENET device and starts the Tx queue.
465  */
466 static s32 nps_enet_open(struct net_device *ndev)
467 {
468 	struct nps_enet_priv *priv = netdev_priv(ndev);
469 	s32 err;
470 
471 	/* Reset private variables */
472 	priv->tx_skb = NULL;
473 	priv->ge_mac_cfg_2_value = 0;
474 	priv->ge_mac_cfg_3_value = 0;
475 
476 	/* ge_mac_cfg_3 default values */
477 	priv->ge_mac_cfg_3_value |=
478 		 NPS_ENET_GE_MAC_CFG_3_RX_IFG_TH << CFG_3_RX_IFG_TH_SHIFT;
479 
480 	priv->ge_mac_cfg_3_value |=
481 		 NPS_ENET_GE_MAC_CFG_3_MAX_LEN << CFG_3_MAX_LEN_SHIFT;
482 
483 	/* Disable HW device */
484 	nps_enet_hw_disable_control(ndev);
485 
486 	/* irq Rx allocation */
487 	err = request_irq(priv->irq, nps_enet_irq_handler,
488 			  0, "enet-rx-tx", ndev);
489 	if (err)
490 		return err;
491 
492 	napi_enable(&priv->napi);
493 
494 	/* Enable HW device */
495 	nps_enet_hw_reset(ndev);
496 	nps_enet_hw_enable_control(ndev);
497 
498 	netif_start_queue(ndev);
499 
500 	return 0;
501 }
502 
503 /**
504  * nps_enet_stop - Close the network device.
505  * @ndev:       Pointer to the network device.
506  *
507  * This function stops the Tx queue, disables interrupts for the ENET device.
508  */
509 static s32 nps_enet_stop(struct net_device *ndev)
510 {
511 	struct nps_enet_priv *priv = netdev_priv(ndev);
512 
513 	napi_disable(&priv->napi);
514 	netif_stop_queue(ndev);
515 	nps_enet_hw_disable_control(ndev);
516 	free_irq(priv->irq, ndev);
517 
518 	return 0;
519 }
520 
521 /**
522  * nps_enet_start_xmit - Starts the data transmission.
523  * @skb:        sk_buff pointer that contains data to be Transmitted.
524  * @ndev:       Pointer to net_device structure.
525  *
526  * returns: NETDEV_TX_OK, on success
527  *              NETDEV_TX_BUSY, if any of the descriptors are not free.
528  *
529  * This function is invoked from upper layers to initiate transmission.
530  */
531 static netdev_tx_t nps_enet_start_xmit(struct sk_buff *skb,
532 				       struct net_device *ndev)
533 {
534 	struct nps_enet_priv *priv = netdev_priv(ndev);
535 
536 	/* This driver handles one frame at a time  */
537 	netif_stop_queue(ndev);
538 
539 	priv->tx_skb = skb;
540 
541 	/* make sure tx_skb is actually written to the memory
542 	 * before the HW is informed and the IRQ is fired.
543 	 */
544 	wmb();
545 
546 	nps_enet_send_frame(ndev, skb);
547 
548 	return NETDEV_TX_OK;
549 }
550 
551 #ifdef CONFIG_NET_POLL_CONTROLLER
552 static void nps_enet_poll_controller(struct net_device *ndev)
553 {
554 	disable_irq(ndev->irq);
555 	nps_enet_irq_handler(ndev->irq, ndev);
556 	enable_irq(ndev->irq);
557 }
558 #endif
559 
560 static const struct net_device_ops nps_netdev_ops = {
561 	.ndo_open		= nps_enet_open,
562 	.ndo_stop		= nps_enet_stop,
563 	.ndo_start_xmit		= nps_enet_start_xmit,
564 	.ndo_set_mac_address	= nps_enet_set_mac_address,
565 	.ndo_set_rx_mode        = nps_enet_set_rx_mode,
566 #ifdef CONFIG_NET_POLL_CONTROLLER
567 	.ndo_poll_controller	= nps_enet_poll_controller,
568 #endif
569 };
570 
571 static s32 nps_enet_probe(struct platform_device *pdev)
572 {
573 	struct device *dev = &pdev->dev;
574 	struct net_device *ndev;
575 	struct nps_enet_priv *priv;
576 	s32 err = 0;
577 
578 	if (!dev->of_node)
579 		return -ENODEV;
580 
581 	ndev = alloc_etherdev(sizeof(struct nps_enet_priv));
582 	if (!ndev)
583 		return -ENOMEM;
584 
585 	platform_set_drvdata(pdev, ndev);
586 	SET_NETDEV_DEV(ndev, dev);
587 	priv = netdev_priv(ndev);
588 
589 	/* The EZ NET specific entries in the device structure. */
590 	ndev->netdev_ops = &nps_netdev_ops;
591 	ndev->watchdog_timeo = (400 * HZ / 1000);
592 	/* FIXME :: no multicast support yet */
593 	ndev->flags &= ~IFF_MULTICAST;
594 
595 	priv->regs_base = devm_platform_ioremap_resource(pdev, 0);
596 	if (IS_ERR(priv->regs_base)) {
597 		err = PTR_ERR(priv->regs_base);
598 		goto out_netdev;
599 	}
600 	dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs_base);
601 
602 	/* set kernel MAC address to dev */
603 	err = of_get_ethdev_address(dev->of_node, ndev);
604 	if (err)
605 		eth_hw_addr_random(ndev);
606 
607 	/* Get IRQ number */
608 	priv->irq = platform_get_irq(pdev, 0);
609 	if (priv->irq < 0) {
610 		err = -ENODEV;
611 		goto out_netdev;
612 	}
613 
614 	netif_napi_add_weight(ndev, &priv->napi, nps_enet_poll,
615 			      NPS_ENET_NAPI_POLL_WEIGHT);
616 
617 	/* Register the driver. Should be the last thing in probe */
618 	err = register_netdev(ndev);
619 	if (err) {
620 		dev_err(dev, "Failed to register ndev for %s, err = 0x%08x\n",
621 			ndev->name, (s32)err);
622 		goto out_netif_api;
623 	}
624 
625 	dev_info(dev, "(rx/tx=%d)\n", priv->irq);
626 	return 0;
627 
628 out_netif_api:
629 	netif_napi_del(&priv->napi);
630 out_netdev:
631 	free_netdev(ndev);
632 
633 	return err;
634 }
635 
636 static void nps_enet_remove(struct platform_device *pdev)
637 {
638 	struct net_device *ndev = platform_get_drvdata(pdev);
639 	struct nps_enet_priv *priv = netdev_priv(ndev);
640 
641 	unregister_netdev(ndev);
642 	netif_napi_del(&priv->napi);
643 	free_netdev(ndev);
644 }
645 
646 static const struct of_device_id nps_enet_dt_ids[] = {
647 	{ .compatible = "ezchip,nps-mgt-enet" },
648 	{ /* Sentinel */ }
649 };
650 MODULE_DEVICE_TABLE(of, nps_enet_dt_ids);
651 
652 static struct platform_driver nps_enet_driver = {
653 	.probe = nps_enet_probe,
654 	.remove = nps_enet_remove,
655 	.driver = {
656 		.name = DRV_NAME,
657 		.of_match_table  = nps_enet_dt_ids,
658 	},
659 };
660 
661 module_platform_driver(nps_enet_driver);
662 
663 MODULE_AUTHOR("EZchip Semiconductor");
664 MODULE_DESCRIPTION("EZchip NPS Ethernet driver");
665 MODULE_LICENSE("GPL v2");
666