xref: /linux/drivers/net/ethernet/ezchip/nps_enet.c (revision 8137a49e1567726eb10fcf55ad141ac19804ca6b)
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/of_address.h>
10 #include <linux/of_irq.h>
11 #include <linux/of_net.h>
12 #include <linux/of_platform.h>
13 #include "nps_enet.h"
14 
15 #define DRV_NAME			"nps_mgt_enet"
16 
17 static inline bool nps_enet_is_tx_pending(struct nps_enet_priv *priv)
18 {
19 	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
20 	u32 tx_ctrl_ct = (tx_ctrl_value & TX_CTL_CT_MASK) >> TX_CTL_CT_SHIFT;
21 
22 	return (!tx_ctrl_ct && priv->tx_skb);
23 }
24 
25 static void nps_enet_clean_rx_fifo(struct net_device *ndev, u32 frame_len)
26 {
27 	struct nps_enet_priv *priv = netdev_priv(ndev);
28 	u32 i, len = DIV_ROUND_UP(frame_len, sizeof(u32));
29 
30 	/* Empty Rx FIFO buffer by reading all words */
31 	for (i = 0; i < len; i++)
32 		nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
33 }
34 
35 static void nps_enet_read_rx_fifo(struct net_device *ndev,
36 				  unsigned char *dst, u32 length)
37 {
38 	struct nps_enet_priv *priv = netdev_priv(ndev);
39 	s32 i, last = length & (sizeof(u32) - 1);
40 	u32 *reg = (u32 *)dst, len = length / sizeof(u32);
41 	bool dst_is_aligned = IS_ALIGNED((unsigned long)dst, sizeof(u32));
42 
43 	/* In case dst is not aligned we need an intermediate buffer */
44 	if (dst_is_aligned) {
45 		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, reg, len);
46 		reg += len;
47 	} else { /* !dst_is_aligned */
48 		for (i = 0; i < len; i++, reg++) {
49 			u32 buf = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
50 
51 			put_unaligned_be32(buf, reg);
52 		}
53 	}
54 	/* copy last bytes (if any) */
55 	if (last) {
56 		u32 buf;
57 
58 		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, &buf, 1);
59 		memcpy((u8 *)reg, &buf, last);
60 	}
61 }
62 
63 static u32 nps_enet_rx_handler(struct net_device *ndev)
64 {
65 	u32 frame_len, err = 0;
66 	u32 work_done = 0;
67 	struct nps_enet_priv *priv = netdev_priv(ndev);
68 	struct sk_buff *skb;
69 	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
70 	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
71 	u32 rx_ctrl_er = (rx_ctrl_value & RX_CTL_ER_MASK) >> RX_CTL_ER_SHIFT;
72 	u32 rx_ctrl_crc = (rx_ctrl_value & RX_CTL_CRC_MASK) >> RX_CTL_CRC_SHIFT;
73 
74 	frame_len = (rx_ctrl_value & RX_CTL_NR_MASK) >> RX_CTL_NR_SHIFT;
75 
76 	/* Check if we got RX */
77 	if (!rx_ctrl_cr)
78 		return work_done;
79 
80 	/* If we got here there is a work for us */
81 	work_done++;
82 
83 	/* Check Rx error */
84 	if (rx_ctrl_er) {
85 		ndev->stats.rx_errors++;
86 		err = 1;
87 	}
88 
89 	/* Check Rx CRC error */
90 	if (rx_ctrl_crc) {
91 		ndev->stats.rx_crc_errors++;
92 		ndev->stats.rx_dropped++;
93 		err = 1;
94 	}
95 
96 	/* Check Frame length Min 64b */
97 	if (unlikely(frame_len < ETH_ZLEN)) {
98 		ndev->stats.rx_length_errors++;
99 		ndev->stats.rx_dropped++;
100 		err = 1;
101 	}
102 
103 	if (err)
104 		goto rx_irq_clean;
105 
106 	/* Skb allocation */
107 	skb = netdev_alloc_skb_ip_align(ndev, frame_len);
108 	if (unlikely(!skb)) {
109 		ndev->stats.rx_errors++;
110 		ndev->stats.rx_dropped++;
111 		goto rx_irq_clean;
112 	}
113 
114 	/* Copy frame from Rx fifo into the skb */
115 	nps_enet_read_rx_fifo(ndev, skb->data, frame_len);
116 
117 	skb_put(skb, frame_len);
118 	skb->protocol = eth_type_trans(skb, ndev);
119 	skb->ip_summed = CHECKSUM_UNNECESSARY;
120 
121 	ndev->stats.rx_packets++;
122 	ndev->stats.rx_bytes += frame_len;
123 	netif_receive_skb(skb);
124 
125 	goto rx_irq_frame_done;
126 
127 rx_irq_clean:
128 	/* Clean Rx fifo */
129 	nps_enet_clean_rx_fifo(ndev, frame_len);
130 
131 rx_irq_frame_done:
132 	/* Ack Rx ctrl register */
133 	nps_enet_reg_set(priv, NPS_ENET_REG_RX_CTL, 0);
134 
135 	return work_done;
136 }
137 
138 static void nps_enet_tx_handler(struct net_device *ndev)
139 {
140 	struct nps_enet_priv *priv = netdev_priv(ndev);
141 	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
142 	u32 tx_ctrl_et = (tx_ctrl_value & TX_CTL_ET_MASK) >> TX_CTL_ET_SHIFT;
143 	u32 tx_ctrl_nt = (tx_ctrl_value & TX_CTL_NT_MASK) >> TX_CTL_NT_SHIFT;
144 
145 	/* Check if we got TX */
146 	if (!nps_enet_is_tx_pending(priv))
147 		return;
148 
149 	/* Ack Tx ctrl register */
150 	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, 0);
151 
152 	/* Check Tx transmit error */
153 	if (unlikely(tx_ctrl_et)) {
154 		ndev->stats.tx_errors++;
155 	} else {
156 		ndev->stats.tx_packets++;
157 		ndev->stats.tx_bytes += tx_ctrl_nt;
158 	}
159 
160 	dev_kfree_skb(priv->tx_skb);
161 	priv->tx_skb = NULL;
162 
163 	if (netif_queue_stopped(ndev))
164 		netif_wake_queue(ndev);
165 }
166 
167 /**
168  * nps_enet_poll - NAPI poll handler.
169  * @napi:       Pointer to napi_struct structure.
170  * @budget:     How many frames to process on one call.
171  *
172  * returns:     Number of processed frames
173  */
174 static int nps_enet_poll(struct napi_struct *napi, int budget)
175 {
176 	struct net_device *ndev = napi->dev;
177 	struct nps_enet_priv *priv = netdev_priv(ndev);
178 	u32 work_done;
179 
180 	nps_enet_tx_handler(ndev);
181 	work_done = nps_enet_rx_handler(ndev);
182 	if ((work_done < budget) && napi_complete_done(napi, work_done)) {
183 		u32 buf_int_enable_value = 0;
184 
185 		/* set tx_done and rx_rdy bits */
186 		buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
187 		buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
188 
189 		nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
190 				 buf_int_enable_value);
191 
192 		/* in case we will get a tx interrupt while interrupts
193 		 * are masked, we will lose it since the tx is edge interrupt.
194 		 * specifically, while executing the code section above,
195 		 * between nps_enet_tx_handler and the interrupts enable, all
196 		 * tx requests will be stuck until we will get an rx interrupt.
197 		 * the two code lines below will solve this situation by
198 		 * re-adding ourselves to the poll list.
199 		 */
200 		if (nps_enet_is_tx_pending(priv)) {
201 			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
202 			napi_reschedule(napi);
203 		}
204 	}
205 
206 	return work_done;
207 }
208 
209 /**
210  * nps_enet_irq_handler - Global interrupt handler for ENET.
211  * @irq:                irq number.
212  * @dev_instance:       device instance.
213  *
214  * returns: IRQ_HANDLED for all cases.
215  *
216  * EZchip ENET has 2 interrupt causes, and depending on bits raised in
217  * CTRL registers we may tell what is a reason for interrupt to fire up.
218  * We got one for RX and the other for TX (completion).
219  */
220 static irqreturn_t nps_enet_irq_handler(s32 irq, void *dev_instance)
221 {
222 	struct net_device *ndev = dev_instance;
223 	struct nps_enet_priv *priv = netdev_priv(ndev);
224 	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
225 	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
226 
227 	if (nps_enet_is_tx_pending(priv) || rx_ctrl_cr)
228 		if (likely(napi_schedule_prep(&priv->napi))) {
229 			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
230 			__napi_schedule(&priv->napi);
231 		}
232 
233 	return IRQ_HANDLED;
234 }
235 
236 static void nps_enet_set_hw_mac_address(struct net_device *ndev)
237 {
238 	struct nps_enet_priv *priv = netdev_priv(ndev);
239 	u32 ge_mac_cfg_1_value = 0;
240 	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
241 
242 	/* set MAC address in HW */
243 	ge_mac_cfg_1_value |= ndev->dev_addr[0] << CFG_1_OCTET_0_SHIFT;
244 	ge_mac_cfg_1_value |= ndev->dev_addr[1] << CFG_1_OCTET_1_SHIFT;
245 	ge_mac_cfg_1_value |= ndev->dev_addr[2] << CFG_1_OCTET_2_SHIFT;
246 	ge_mac_cfg_1_value |= ndev->dev_addr[3] << CFG_1_OCTET_3_SHIFT;
247 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_4_MASK)
248 		 | ndev->dev_addr[4] << CFG_2_OCTET_4_SHIFT;
249 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_5_MASK)
250 		 | ndev->dev_addr[5] << CFG_2_OCTET_5_SHIFT;
251 
252 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_1,
253 			 ge_mac_cfg_1_value);
254 
255 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
256 			 *ge_mac_cfg_2_value);
257 }
258 
259 /**
260  * nps_enet_hw_reset - Reset the network device.
261  * @ndev:       Pointer to the network device.
262  *
263  * This function reset the PCS and TX fifo.
264  * The programming model is to set the relevant reset bits
265  * wait for some time for this to propagate and then unset
266  * the reset bits. This way we ensure that reset procedure
267  * is done successfully by device.
268  */
269 static void nps_enet_hw_reset(struct net_device *ndev)
270 {
271 	struct nps_enet_priv *priv = netdev_priv(ndev);
272 	u32 ge_rst_value = 0, phase_fifo_ctl_value = 0;
273 
274 	/* Pcs reset sequence*/
275 	ge_rst_value |= NPS_ENET_ENABLE << RST_GMAC_0_SHIFT;
276 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
277 	usleep_range(10, 20);
278 	ge_rst_value = 0;
279 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
280 
281 	/* Tx fifo reset sequence */
282 	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_RST_SHIFT;
283 	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_INIT_SHIFT;
284 	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
285 			 phase_fifo_ctl_value);
286 	usleep_range(10, 20);
287 	phase_fifo_ctl_value = 0;
288 	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
289 			 phase_fifo_ctl_value);
290 }
291 
292 static void nps_enet_hw_enable_control(struct net_device *ndev)
293 {
294 	struct nps_enet_priv *priv = netdev_priv(ndev);
295 	u32 ge_mac_cfg_0_value = 0, buf_int_enable_value = 0;
296 	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
297 	u32 *ge_mac_cfg_3_value = &priv->ge_mac_cfg_3_value;
298 	s32 max_frame_length;
299 
300 	/* Enable Rx and Tx statistics */
301 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_STAT_EN_MASK)
302 		 | NPS_ENET_GE_MAC_CFG_2_STAT_EN << CFG_2_STAT_EN_SHIFT;
303 
304 	/* Discard packets with different MAC address */
305 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
306 		 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
307 
308 	/* Discard multicast packets */
309 	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
310 		 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
311 
312 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
313 			 *ge_mac_cfg_2_value);
314 
315 	/* Discard Packets bigger than max frame length */
316 	max_frame_length = ETH_HLEN + ndev->mtu + ETH_FCS_LEN;
317 	if (max_frame_length <= NPS_ENET_MAX_FRAME_LENGTH) {
318 		*ge_mac_cfg_3_value =
319 			 (*ge_mac_cfg_3_value & ~CFG_3_MAX_LEN_MASK)
320 			 | max_frame_length << CFG_3_MAX_LEN_SHIFT;
321 	}
322 
323 	/* Enable interrupts */
324 	buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
325 	buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
326 	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
327 			 buf_int_enable_value);
328 
329 	/* Write device MAC address to HW */
330 	nps_enet_set_hw_mac_address(ndev);
331 
332 	/* Rx and Tx HW features */
333 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_PAD_EN_SHIFT;
334 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_CRC_EN_SHIFT;
335 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_CRC_STRIP_SHIFT;
336 
337 	/* IFG configuration */
338 	ge_mac_cfg_0_value |=
339 		 NPS_ENET_GE_MAC_CFG_0_RX_IFG << CFG_0_RX_IFG_SHIFT;
340 	ge_mac_cfg_0_value |=
341 		 NPS_ENET_GE_MAC_CFG_0_TX_IFG << CFG_0_TX_IFG_SHIFT;
342 
343 	/* preamble configuration */
344 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_PR_CHECK_EN_SHIFT;
345 	ge_mac_cfg_0_value |=
346 		 NPS_ENET_GE_MAC_CFG_0_TX_PR_LEN << CFG_0_TX_PR_LEN_SHIFT;
347 
348 	/* enable flow control frames */
349 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_FC_EN_SHIFT;
350 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_FC_EN_SHIFT;
351 	ge_mac_cfg_0_value |=
352 		 NPS_ENET_GE_MAC_CFG_0_TX_FC_RETR << CFG_0_TX_FC_RETR_SHIFT;
353 	*ge_mac_cfg_3_value = (*ge_mac_cfg_3_value & ~CFG_3_CF_DROP_MASK)
354 		 | NPS_ENET_ENABLE << CFG_3_CF_DROP_SHIFT;
355 
356 	/* Enable Rx and Tx */
357 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_EN_SHIFT;
358 	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_EN_SHIFT;
359 
360 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_3,
361 			 *ge_mac_cfg_3_value);
362 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0,
363 			 ge_mac_cfg_0_value);
364 }
365 
366 static void nps_enet_hw_disable_control(struct net_device *ndev)
367 {
368 	struct nps_enet_priv *priv = netdev_priv(ndev);
369 
370 	/* Disable interrupts */
371 	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
372 
373 	/* Disable Rx and Tx */
374 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0, 0);
375 }
376 
377 static void nps_enet_send_frame(struct net_device *ndev,
378 				struct sk_buff *skb)
379 {
380 	struct nps_enet_priv *priv = netdev_priv(ndev);
381 	u32 tx_ctrl_value = 0;
382 	short length = skb->len;
383 	u32 i, len = DIV_ROUND_UP(length, sizeof(u32));
384 	u32 *src = (void *)skb->data;
385 	bool src_is_aligned = IS_ALIGNED((unsigned long)src, sizeof(u32));
386 
387 	/* In case src is not aligned we need an intermediate buffer */
388 	if (src_is_aligned)
389 		iowrite32_rep(priv->regs_base + NPS_ENET_REG_TX_BUF, src, len);
390 	else /* !src_is_aligned */
391 		for (i = 0; i < len; i++, src++)
392 			nps_enet_reg_set(priv, NPS_ENET_REG_TX_BUF,
393 					 get_unaligned_be32(src));
394 
395 	/* Write the length of the Frame */
396 	tx_ctrl_value |= length << TX_CTL_NT_SHIFT;
397 
398 	tx_ctrl_value |= NPS_ENET_ENABLE << TX_CTL_CT_SHIFT;
399 	/* Send Frame */
400 	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, tx_ctrl_value);
401 }
402 
403 /**
404  * nps_enet_set_mac_address - Set the MAC address for this device.
405  * @ndev:       Pointer to net_device structure.
406  * @p:          6 byte Address to be written as MAC address.
407  *
408  * This function copies the HW address from the sockaddr structure to the
409  * net_device structure and updates the address in HW.
410  *
411  * returns:     -EBUSY if the net device is busy or 0 if the address is set
412  *              successfully.
413  */
414 static s32 nps_enet_set_mac_address(struct net_device *ndev, void *p)
415 {
416 	struct sockaddr *addr = p;
417 	s32 res;
418 
419 	if (netif_running(ndev))
420 		return -EBUSY;
421 
422 	res = eth_mac_addr(ndev, p);
423 	if (!res) {
424 		ether_addr_copy(ndev->dev_addr, addr->sa_data);
425 		nps_enet_set_hw_mac_address(ndev);
426 	}
427 
428 	return res;
429 }
430 
431 /**
432  * nps_enet_set_rx_mode - Change the receive filtering mode.
433  * @ndev:       Pointer to the network device.
434  *
435  * This function enables/disables promiscuous mode
436  */
437 static void nps_enet_set_rx_mode(struct net_device *ndev)
438 {
439 	struct nps_enet_priv *priv = netdev_priv(ndev);
440 	u32 ge_mac_cfg_2_value = priv->ge_mac_cfg_2_value;
441 
442 	if (ndev->flags & IFF_PROMISC) {
443 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
444 			 | NPS_ENET_DISABLE << CFG_2_DISK_DA_SHIFT;
445 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
446 			 | NPS_ENET_DISABLE << CFG_2_DISK_MC_SHIFT;
447 
448 	} else {
449 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
450 			 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
451 		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
452 			 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
453 	}
454 
455 	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2, ge_mac_cfg_2_value);
456 }
457 
458 /**
459  * nps_enet_open - Open the network device.
460  * @ndev:       Pointer to the network device.
461  *
462  * returns: 0, on success or non-zero error value on failure.
463  *
464  * This function sets the MAC address, requests and enables an IRQ
465  * for the ENET device and starts the Tx queue.
466  */
467 static s32 nps_enet_open(struct net_device *ndev)
468 {
469 	struct nps_enet_priv *priv = netdev_priv(ndev);
470 	s32 err;
471 
472 	/* Reset private variables */
473 	priv->tx_skb = NULL;
474 	priv->ge_mac_cfg_2_value = 0;
475 	priv->ge_mac_cfg_3_value = 0;
476 
477 	/* ge_mac_cfg_3 default values */
478 	priv->ge_mac_cfg_3_value |=
479 		 NPS_ENET_GE_MAC_CFG_3_RX_IFG_TH << CFG_3_RX_IFG_TH_SHIFT;
480 
481 	priv->ge_mac_cfg_3_value |=
482 		 NPS_ENET_GE_MAC_CFG_3_MAX_LEN << CFG_3_MAX_LEN_SHIFT;
483 
484 	/* Disable HW device */
485 	nps_enet_hw_disable_control(ndev);
486 
487 	/* irq Rx allocation */
488 	err = request_irq(priv->irq, nps_enet_irq_handler,
489 			  0, "enet-rx-tx", ndev);
490 	if (err)
491 		return err;
492 
493 	napi_enable(&priv->napi);
494 
495 	/* Enable HW device */
496 	nps_enet_hw_reset(ndev);
497 	nps_enet_hw_enable_control(ndev);
498 
499 	netif_start_queue(ndev);
500 
501 	return 0;
502 }
503 
504 /**
505  * nps_enet_stop - Close the network device.
506  * @ndev:       Pointer to the network device.
507  *
508  * This function stops the Tx queue, disables interrupts for the ENET device.
509  */
510 static s32 nps_enet_stop(struct net_device *ndev)
511 {
512 	struct nps_enet_priv *priv = netdev_priv(ndev);
513 
514 	napi_disable(&priv->napi);
515 	netif_stop_queue(ndev);
516 	nps_enet_hw_disable_control(ndev);
517 	free_irq(priv->irq, ndev);
518 
519 	return 0;
520 }
521 
522 /**
523  * nps_enet_start_xmit - Starts the data transmission.
524  * @skb:        sk_buff pointer that contains data to be Transmitted.
525  * @ndev:       Pointer to net_device structure.
526  *
527  * returns: NETDEV_TX_OK, on success
528  *              NETDEV_TX_BUSY, if any of the descriptors are not free.
529  *
530  * This function is invoked from upper layers to initiate transmission.
531  */
532 static netdev_tx_t nps_enet_start_xmit(struct sk_buff *skb,
533 				       struct net_device *ndev)
534 {
535 	struct nps_enet_priv *priv = netdev_priv(ndev);
536 
537 	/* This driver handles one frame at a time  */
538 	netif_stop_queue(ndev);
539 
540 	priv->tx_skb = skb;
541 
542 	/* make sure tx_skb is actually written to the memory
543 	 * before the HW is informed and the IRQ is fired.
544 	 */
545 	wmb();
546 
547 	nps_enet_send_frame(ndev, skb);
548 
549 	return NETDEV_TX_OK;
550 }
551 
552 #ifdef CONFIG_NET_POLL_CONTROLLER
553 static void nps_enet_poll_controller(struct net_device *ndev)
554 {
555 	disable_irq(ndev->irq);
556 	nps_enet_irq_handler(ndev->irq, ndev);
557 	enable_irq(ndev->irq);
558 }
559 #endif
560 
561 static const struct net_device_ops nps_netdev_ops = {
562 	.ndo_open		= nps_enet_open,
563 	.ndo_stop		= nps_enet_stop,
564 	.ndo_start_xmit		= nps_enet_start_xmit,
565 	.ndo_set_mac_address	= nps_enet_set_mac_address,
566 	.ndo_set_rx_mode        = nps_enet_set_rx_mode,
567 #ifdef CONFIG_NET_POLL_CONTROLLER
568 	.ndo_poll_controller	= nps_enet_poll_controller,
569 #endif
570 };
571 
572 static s32 nps_enet_probe(struct platform_device *pdev)
573 {
574 	struct device *dev = &pdev->dev;
575 	struct net_device *ndev;
576 	struct nps_enet_priv *priv;
577 	s32 err = 0;
578 
579 	if (!dev->of_node)
580 		return -ENODEV;
581 
582 	ndev = alloc_etherdev(sizeof(struct nps_enet_priv));
583 	if (!ndev)
584 		return -ENOMEM;
585 
586 	platform_set_drvdata(pdev, ndev);
587 	SET_NETDEV_DEV(ndev, dev);
588 	priv = netdev_priv(ndev);
589 
590 	/* The EZ NET specific entries in the device structure. */
591 	ndev->netdev_ops = &nps_netdev_ops;
592 	ndev->watchdog_timeo = (400 * HZ / 1000);
593 	/* FIXME :: no multicast support yet */
594 	ndev->flags &= ~IFF_MULTICAST;
595 
596 	priv->regs_base = devm_platform_ioremap_resource(pdev, 0);
597 	if (IS_ERR(priv->regs_base)) {
598 		err = PTR_ERR(priv->regs_base);
599 		goto out_netdev;
600 	}
601 	dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs_base);
602 
603 	/* set kernel MAC address to dev */
604 	err = of_get_mac_address(dev->of_node, ndev->dev_addr);
605 	if (err)
606 		eth_hw_addr_random(ndev);
607 
608 	/* Get IRQ number */
609 	priv->irq = platform_get_irq(pdev, 0);
610 	if (priv->irq < 0) {
611 		dev_err(dev, "failed to retrieve <irq Rx-Tx> value from device tree\n");
612 		err = -ENODEV;
613 		goto out_netdev;
614 	}
615 
616 	netif_napi_add(ndev, &priv->napi, nps_enet_poll,
617 		       NPS_ENET_NAPI_POLL_WEIGHT);
618 
619 	/* Register the driver. Should be the last thing in probe */
620 	err = register_netdev(ndev);
621 	if (err) {
622 		dev_err(dev, "Failed to register ndev for %s, err = 0x%08x\n",
623 			ndev->name, (s32)err);
624 		goto out_netif_api;
625 	}
626 
627 	dev_info(dev, "(rx/tx=%d)\n", priv->irq);
628 	return 0;
629 
630 out_netif_api:
631 	netif_napi_del(&priv->napi);
632 out_netdev:
633 	free_netdev(ndev);
634 
635 	return err;
636 }
637 
638 static s32 nps_enet_remove(struct platform_device *pdev)
639 {
640 	struct net_device *ndev = platform_get_drvdata(pdev);
641 	struct nps_enet_priv *priv = netdev_priv(ndev);
642 
643 	unregister_netdev(ndev);
644 	netif_napi_del(&priv->napi);
645 	free_netdev(ndev);
646 
647 	return 0;
648 }
649 
650 static const struct of_device_id nps_enet_dt_ids[] = {
651 	{ .compatible = "ezchip,nps-mgt-enet" },
652 	{ /* Sentinel */ }
653 };
654 MODULE_DEVICE_TABLE(of, nps_enet_dt_ids);
655 
656 static struct platform_driver nps_enet_driver = {
657 	.probe = nps_enet_probe,
658 	.remove = nps_enet_remove,
659 	.driver = {
660 		.name = DRV_NAME,
661 		.of_match_table  = nps_enet_dt_ids,
662 	},
663 };
664 
665 module_platform_driver(nps_enet_driver);
666 
667 MODULE_AUTHOR("EZchip Semiconductor");
668 MODULE_LICENSE("GPL v2");
669