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  1/*
  2 * Copyright(c) 2015 EZchip Technologies.
  3 *
  4 * This program is free software; you can redistribute it and/or modify it
  5 * under the terms and conditions of the GNU General Public License,
  6 * version 2, as published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope it will be useful, but WITHOUT
  9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 11 * more details.
 12 *
 13 * The full GNU General Public License is included in this distribution in
 14 * the file called "COPYING".
 15 */
 16
 17#include <linux/module.h>
 18#include <linux/etherdevice.h>
 19#include <linux/interrupt.h>
 20#include <linux/of_address.h>
 21#include <linux/of_irq.h>
 22#include <linux/of_net.h>
 23#include <linux/of_platform.h>
 24#include "nps_enet.h"
 25
 26#define DRV_NAME			"nps_mgt_enet"
 27
 28static inline bool nps_enet_is_tx_pending(struct nps_enet_priv *priv)
 29{
 30	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
 31	u32 tx_ctrl_ct = (tx_ctrl_value & TX_CTL_CT_MASK) >> TX_CTL_CT_SHIFT;
 32
 33	return (!tx_ctrl_ct && priv->tx_skb);
 34}
 35
 36static void nps_enet_clean_rx_fifo(struct net_device *ndev, u32 frame_len)
 37{
 38	struct nps_enet_priv *priv = netdev_priv(ndev);
 39	u32 i, len = DIV_ROUND_UP(frame_len, sizeof(u32));
 40
 41	/* Empty Rx FIFO buffer by reading all words */
 42	for (i = 0; i < len; i++)
 43		nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
 44}
 45
 46static void nps_enet_read_rx_fifo(struct net_device *ndev,
 47				  unsigned char *dst, u32 length)
 48{
 49	struct nps_enet_priv *priv = netdev_priv(ndev);
 50	s32 i, last = length & (sizeof(u32) - 1);
 51	u32 *reg = (u32 *)dst, len = length / sizeof(u32);
 52	bool dst_is_aligned = IS_ALIGNED((unsigned long)dst, sizeof(u32));
 53
 54	/* In case dst is not aligned we need an intermediate buffer */
 55	if (dst_is_aligned) {
 56		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, reg, len);
 57		reg += len;
 58	} else { /* !dst_is_aligned */
 59		for (i = 0; i < len; i++, reg++) {
 60			u32 buf = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
 61
 62			put_unaligned_be32(buf, reg);
 63		}
 64	}
 65	/* copy last bytes (if any) */
 66	if (last) {
 67		u32 buf;
 68
 69		ioread32_rep(priv->regs_base + NPS_ENET_REG_RX_BUF, &buf, 1);
 70		memcpy((u8 *)reg, &buf, last);
 71	}
 72}
 73
 74static u32 nps_enet_rx_handler(struct net_device *ndev)
 75{
 76	u32 frame_len, err = 0;
 77	u32 work_done = 0;
 78	struct nps_enet_priv *priv = netdev_priv(ndev);
 79	struct sk_buff *skb;
 80	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
 81	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
 82	u32 rx_ctrl_er = (rx_ctrl_value & RX_CTL_ER_MASK) >> RX_CTL_ER_SHIFT;
 83	u32 rx_ctrl_crc = (rx_ctrl_value & RX_CTL_CRC_MASK) >> RX_CTL_CRC_SHIFT;
 84
 85	frame_len = (rx_ctrl_value & RX_CTL_NR_MASK) >> RX_CTL_NR_SHIFT;
 86
 87	/* Check if we got RX */
 88	if (!rx_ctrl_cr)
 89		return work_done;
 90
 91	/* If we got here there is a work for us */
 92	work_done++;
 93
 94	/* Check Rx error */
 95	if (rx_ctrl_er) {
 96		ndev->stats.rx_errors++;
 97		err = 1;
 98	}
 99
100	/* Check Rx CRC error */
101	if (rx_ctrl_crc) {
102		ndev->stats.rx_crc_errors++;
103		ndev->stats.rx_dropped++;
104		err = 1;
105	}
106
107	/* Check Frame length Min 64b */
108	if (unlikely(frame_len < ETH_ZLEN)) {
109		ndev->stats.rx_length_errors++;
110		ndev->stats.rx_dropped++;
111		err = 1;
112	}
113
114	if (err)
115		goto rx_irq_clean;
116
117	/* Skb allocation */
118	skb = netdev_alloc_skb_ip_align(ndev, frame_len);
119	if (unlikely(!skb)) {
120		ndev->stats.rx_errors++;
121		ndev->stats.rx_dropped++;
122		goto rx_irq_clean;
123	}
124
125	/* Copy frame from Rx fifo into the skb */
126	nps_enet_read_rx_fifo(ndev, skb->data, frame_len);
127
128	skb_put(skb, frame_len);
129	skb->protocol = eth_type_trans(skb, ndev);
130	skb->ip_summed = CHECKSUM_UNNECESSARY;
131
132	ndev->stats.rx_packets++;
133	ndev->stats.rx_bytes += frame_len;
134	netif_receive_skb(skb);
135
136	goto rx_irq_frame_done;
137
138rx_irq_clean:
139	/* Clean Rx fifo */
140	nps_enet_clean_rx_fifo(ndev, frame_len);
141
142rx_irq_frame_done:
143	/* Ack Rx ctrl register */
144	nps_enet_reg_set(priv, NPS_ENET_REG_RX_CTL, 0);
145
146	return work_done;
147}
148
149static void nps_enet_tx_handler(struct net_device *ndev)
150{
151	struct nps_enet_priv *priv = netdev_priv(ndev);
152	u32 tx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);
153	u32 tx_ctrl_et = (tx_ctrl_value & TX_CTL_ET_MASK) >> TX_CTL_ET_SHIFT;
154	u32 tx_ctrl_nt = (tx_ctrl_value & TX_CTL_NT_MASK) >> TX_CTL_NT_SHIFT;
155
156	/* Check if we got TX */
157	if (!nps_enet_is_tx_pending(priv))
158		return;
159
160	/* Ack Tx ctrl register */
161	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, 0);
162
163	/* Check Tx transmit error */
164	if (unlikely(tx_ctrl_et)) {
165		ndev->stats.tx_errors++;
166	} else {
167		ndev->stats.tx_packets++;
168		ndev->stats.tx_bytes += tx_ctrl_nt;
169	}
170
171	dev_kfree_skb(priv->tx_skb);
172	priv->tx_skb = NULL;
173
174	if (netif_queue_stopped(ndev))
175		netif_wake_queue(ndev);
176}
177
178/**
179 * nps_enet_poll - NAPI poll handler.
180 * @napi:       Pointer to napi_struct structure.
181 * @budget:     How many frames to process on one call.
182 *
183 * returns:     Number of processed frames
184 */
185static int nps_enet_poll(struct napi_struct *napi, int budget)
186{
187	struct net_device *ndev = napi->dev;
188	struct nps_enet_priv *priv = netdev_priv(ndev);
189	u32 work_done;
190
191	nps_enet_tx_handler(ndev);
192	work_done = nps_enet_rx_handler(ndev);
193	if ((work_done < budget) && napi_complete_done(napi, work_done)) {
194		u32 buf_int_enable_value = 0;
195
196		/* set tx_done and rx_rdy bits */
197		buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
198		buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
199
200		nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
201				 buf_int_enable_value);
202
203		/* in case we will get a tx interrupt while interrupts
204		 * are masked, we will lose it since the tx is edge interrupt.
205		 * specifically, while executing the code section above,
206		 * between nps_enet_tx_handler and the interrupts enable, all
207		 * tx requests will be stuck until we will get an rx interrupt.
208		 * the two code lines below will solve this situation by
209		 * re-adding ourselves to the poll list.
210		 */
211		if (nps_enet_is_tx_pending(priv)) {
212			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
213			napi_reschedule(napi);
214		}
215	}
216
217	return work_done;
218}
219
220/**
221 * nps_enet_irq_handler - Global interrupt handler for ENET.
222 * @irq:                irq number.
223 * @dev_instance:       device instance.
224 *
225 * returns: IRQ_HANDLED for all cases.
226 *
227 * EZchip ENET has 2 interrupt causes, and depending on bits raised in
228 * CTRL registers we may tell what is a reason for interrupt to fire up.
229 * We got one for RX and the other for TX (completion).
230 */
231static irqreturn_t nps_enet_irq_handler(s32 irq, void *dev_instance)
232{
233	struct net_device *ndev = dev_instance;
234	struct nps_enet_priv *priv = netdev_priv(ndev);
235	u32 rx_ctrl_value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
236	u32 rx_ctrl_cr = (rx_ctrl_value & RX_CTL_CR_MASK) >> RX_CTL_CR_SHIFT;
237
238	if (nps_enet_is_tx_pending(priv) || rx_ctrl_cr)
239		if (likely(napi_schedule_prep(&priv->napi))) {
240			nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
241			__napi_schedule(&priv->napi);
242		}
243
244	return IRQ_HANDLED;
245}
246
247static void nps_enet_set_hw_mac_address(struct net_device *ndev)
248{
249	struct nps_enet_priv *priv = netdev_priv(ndev);
250	u32 ge_mac_cfg_1_value = 0;
251	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
252
253	/* set MAC address in HW */
254	ge_mac_cfg_1_value |= ndev->dev_addr[0] << CFG_1_OCTET_0_SHIFT;
255	ge_mac_cfg_1_value |= ndev->dev_addr[1] << CFG_1_OCTET_1_SHIFT;
256	ge_mac_cfg_1_value |= ndev->dev_addr[2] << CFG_1_OCTET_2_SHIFT;
257	ge_mac_cfg_1_value |= ndev->dev_addr[3] << CFG_1_OCTET_3_SHIFT;
258	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_4_MASK)
259		 | ndev->dev_addr[4] << CFG_2_OCTET_4_SHIFT;
260	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_OCTET_5_MASK)
261		 | ndev->dev_addr[5] << CFG_2_OCTET_5_SHIFT;
262
263	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_1,
264			 ge_mac_cfg_1_value);
265
266	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
267			 *ge_mac_cfg_2_value);
268}
269
270/**
271 * nps_enet_hw_reset - Reset the network device.
272 * @ndev:       Pointer to the network device.
273 *
274 * This function reset the PCS and TX fifo.
275 * The programming model is to set the relevant reset bits
276 * wait for some time for this to propagate and then unset
277 * the reset bits. This way we ensure that reset procedure
278 * is done successfully by device.
279 */
280static void nps_enet_hw_reset(struct net_device *ndev)
281{
282	struct nps_enet_priv *priv = netdev_priv(ndev);
283	u32 ge_rst_value = 0, phase_fifo_ctl_value = 0;
284
285	/* Pcs reset sequence*/
286	ge_rst_value |= NPS_ENET_ENABLE << RST_GMAC_0_SHIFT;
287	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
288	usleep_range(10, 20);
289	ge_rst_value = 0;
290	nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst_value);
291
292	/* Tx fifo reset sequence */
293	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_RST_SHIFT;
294	phase_fifo_ctl_value |= NPS_ENET_ENABLE << PHASE_FIFO_CTL_INIT_SHIFT;
295	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
296			 phase_fifo_ctl_value);
297	usleep_range(10, 20);
298	phase_fifo_ctl_value = 0;
299	nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
300			 phase_fifo_ctl_value);
301}
302
303static void nps_enet_hw_enable_control(struct net_device *ndev)
304{
305	struct nps_enet_priv *priv = netdev_priv(ndev);
306	u32 ge_mac_cfg_0_value = 0, buf_int_enable_value = 0;
307	u32 *ge_mac_cfg_2_value = &priv->ge_mac_cfg_2_value;
308	u32 *ge_mac_cfg_3_value = &priv->ge_mac_cfg_3_value;
309	s32 max_frame_length;
310
311	/* Enable Rx and Tx statistics */
312	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_STAT_EN_MASK)
313		 | NPS_ENET_GE_MAC_CFG_2_STAT_EN << CFG_2_STAT_EN_SHIFT;
314
315	/* Discard packets with different MAC address */
316	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
317		 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
318
319	/* Discard multicast packets */
320	*ge_mac_cfg_2_value = (*ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
321		 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
322
323	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
324			 *ge_mac_cfg_2_value);
325
326	/* Discard Packets bigger than max frame length */
327	max_frame_length = ETH_HLEN + ndev->mtu + ETH_FCS_LEN;
328	if (max_frame_length <= NPS_ENET_MAX_FRAME_LENGTH) {
329		*ge_mac_cfg_3_value =
330			 (*ge_mac_cfg_3_value & ~CFG_3_MAX_LEN_MASK)
331			 | max_frame_length << CFG_3_MAX_LEN_SHIFT;
332	}
333
334	/* Enable interrupts */
335	buf_int_enable_value |= NPS_ENET_ENABLE << RX_RDY_SHIFT;
336	buf_int_enable_value |= NPS_ENET_ENABLE << TX_DONE_SHIFT;
337	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
338			 buf_int_enable_value);
339
340	/* Write device MAC address to HW */
341	nps_enet_set_hw_mac_address(ndev);
342
343	/* Rx and Tx HW features */
344	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_PAD_EN_SHIFT;
345	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_CRC_EN_SHIFT;
346	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_CRC_STRIP_SHIFT;
347
348	/* IFG configuration */
349	ge_mac_cfg_0_value |=
350		 NPS_ENET_GE_MAC_CFG_0_RX_IFG << CFG_0_RX_IFG_SHIFT;
351	ge_mac_cfg_0_value |=
352		 NPS_ENET_GE_MAC_CFG_0_TX_IFG << CFG_0_TX_IFG_SHIFT;
353
354	/* preamble configuration */
355	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_PR_CHECK_EN_SHIFT;
356	ge_mac_cfg_0_value |=
357		 NPS_ENET_GE_MAC_CFG_0_TX_PR_LEN << CFG_0_TX_PR_LEN_SHIFT;
358
359	/* enable flow control frames */
360	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_FC_EN_SHIFT;
361	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_FC_EN_SHIFT;
362	ge_mac_cfg_0_value |=
363		 NPS_ENET_GE_MAC_CFG_0_TX_FC_RETR << CFG_0_TX_FC_RETR_SHIFT;
364	*ge_mac_cfg_3_value = (*ge_mac_cfg_3_value & ~CFG_3_CF_DROP_MASK)
365		 | NPS_ENET_ENABLE << CFG_3_CF_DROP_SHIFT;
366
367	/* Enable Rx and Tx */
368	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_RX_EN_SHIFT;
369	ge_mac_cfg_0_value |= NPS_ENET_ENABLE << CFG_0_TX_EN_SHIFT;
370
371	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_3,
372			 *ge_mac_cfg_3_value);
373	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0,
374			 ge_mac_cfg_0_value);
375}
376
377static void nps_enet_hw_disable_control(struct net_device *ndev)
378{
379	struct nps_enet_priv *priv = netdev_priv(ndev);
380
381	/* Disable interrupts */
382	nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
383
384	/* Disable Rx and Tx */
385	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0, 0);
386}
387
388static void nps_enet_send_frame(struct net_device *ndev,
389				struct sk_buff *skb)
390{
391	struct nps_enet_priv *priv = netdev_priv(ndev);
392	u32 tx_ctrl_value = 0;
393	short length = skb->len;
394	u32 i, len = DIV_ROUND_UP(length, sizeof(u32));
395	u32 *src = (void *)skb->data;
396	bool src_is_aligned = IS_ALIGNED((unsigned long)src, sizeof(u32));
397
398	/* In case src is not aligned we need an intermediate buffer */
399	if (src_is_aligned)
400		iowrite32_rep(priv->regs_base + NPS_ENET_REG_TX_BUF, src, len);
401	else /* !src_is_aligned */
402		for (i = 0; i < len; i++, src++)
403			nps_enet_reg_set(priv, NPS_ENET_REG_TX_BUF,
404					 get_unaligned_be32(src));
405
406	/* Write the length of the Frame */
407	tx_ctrl_value |= length << TX_CTL_NT_SHIFT;
408
409	tx_ctrl_value |= NPS_ENET_ENABLE << TX_CTL_CT_SHIFT;
410	/* Send Frame */
411	nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, tx_ctrl_value);
412}
413
414/**
415 * nps_enet_set_mac_address - Set the MAC address for this device.
416 * @ndev:       Pointer to net_device structure.
417 * @p:          6 byte Address to be written as MAC address.
418 *
419 * This function copies the HW address from the sockaddr structure to the
420 * net_device structure and updates the address in HW.
421 *
422 * returns:     -EBUSY if the net device is busy or 0 if the address is set
423 *              successfully.
424 */
425static s32 nps_enet_set_mac_address(struct net_device *ndev, void *p)
426{
427	struct sockaddr *addr = p;
428	s32 res;
429
430	if (netif_running(ndev))
431		return -EBUSY;
432
433	res = eth_mac_addr(ndev, p);
434	if (!res) {
435		ether_addr_copy(ndev->dev_addr, addr->sa_data);
436		nps_enet_set_hw_mac_address(ndev);
437	}
438
439	return res;
440}
441
442/**
443 * nps_enet_set_rx_mode - Change the receive filtering mode.
444 * @ndev:       Pointer to the network device.
445 *
446 * This function enables/disables promiscuous mode
447 */
448static void nps_enet_set_rx_mode(struct net_device *ndev)
449{
450	struct nps_enet_priv *priv = netdev_priv(ndev);
451	u32 ge_mac_cfg_2_value = priv->ge_mac_cfg_2_value;
452
453	if (ndev->flags & IFF_PROMISC) {
454		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
455			 | NPS_ENET_DISABLE << CFG_2_DISK_DA_SHIFT;
456		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
457			 | NPS_ENET_DISABLE << CFG_2_DISK_MC_SHIFT;
458
459	} else {
460		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_DA_MASK)
461			 | NPS_ENET_ENABLE << CFG_2_DISK_DA_SHIFT;
462		ge_mac_cfg_2_value = (ge_mac_cfg_2_value & ~CFG_2_DISK_MC_MASK)
463			 | NPS_ENET_ENABLE << CFG_2_DISK_MC_SHIFT;
464	}
465
466	nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2, ge_mac_cfg_2_value);
467}
468
469/**
470 * nps_enet_open - Open the network device.
471 * @ndev:       Pointer to the network device.
472 *
473 * returns: 0, on success or non-zero error value on failure.
474 *
475 * This function sets the MAC address, requests and enables an IRQ
476 * for the ENET device and starts the Tx queue.
477 */
478static s32 nps_enet_open(struct net_device *ndev)
479{
480	struct nps_enet_priv *priv = netdev_priv(ndev);
481	s32 err;
482
483	/* Reset private variables */
484	priv->tx_skb = NULL;
485	priv->ge_mac_cfg_2_value = 0;
486	priv->ge_mac_cfg_3_value = 0;
487
488	/* ge_mac_cfg_3 default values */
489	priv->ge_mac_cfg_3_value |=
490		 NPS_ENET_GE_MAC_CFG_3_RX_IFG_TH << CFG_3_RX_IFG_TH_SHIFT;
491
492	priv->ge_mac_cfg_3_value |=
493		 NPS_ENET_GE_MAC_CFG_3_MAX_LEN << CFG_3_MAX_LEN_SHIFT;
494
495	/* Disable HW device */
496	nps_enet_hw_disable_control(ndev);
497
498	/* irq Rx allocation */
499	err = request_irq(priv->irq, nps_enet_irq_handler,
500			  0, "enet-rx-tx", ndev);
501	if (err)
502		return err;
503
504	napi_enable(&priv->napi);
505
506	/* Enable HW device */
507	nps_enet_hw_reset(ndev);
508	nps_enet_hw_enable_control(ndev);
509
510	netif_start_queue(ndev);
511
512	return 0;
513}
514
515/**
516 * nps_enet_stop - Close the network device.
517 * @ndev:       Pointer to the network device.
518 *
519 * This function stops the Tx queue, disables interrupts for the ENET device.
520 */
521static s32 nps_enet_stop(struct net_device *ndev)
522{
523	struct nps_enet_priv *priv = netdev_priv(ndev);
524
525	napi_disable(&priv->napi);
526	netif_stop_queue(ndev);
527	nps_enet_hw_disable_control(ndev);
528	free_irq(priv->irq, ndev);
529
530	return 0;
531}
532
533/**
534 * nps_enet_start_xmit - Starts the data transmission.
535 * @skb:        sk_buff pointer that contains data to be Transmitted.
536 * @ndev:       Pointer to net_device structure.
537 *
538 * returns: NETDEV_TX_OK, on success
539 *              NETDEV_TX_BUSY, if any of the descriptors are not free.
540 *
541 * This function is invoked from upper layers to initiate transmission.
542 */
543static netdev_tx_t nps_enet_start_xmit(struct sk_buff *skb,
544				       struct net_device *ndev)
545{
546	struct nps_enet_priv *priv = netdev_priv(ndev);
547
548	/* This driver handles one frame at a time  */
549	netif_stop_queue(ndev);
550
551	priv->tx_skb = skb;
552
553	/* make sure tx_skb is actually written to the memory
554	 * before the HW is informed and the IRQ is fired.
555	 */
556	wmb();
557
558	nps_enet_send_frame(ndev, skb);
559
560	return NETDEV_TX_OK;
561}
562
563#ifdef CONFIG_NET_POLL_CONTROLLER
564static void nps_enet_poll_controller(struct net_device *ndev)
565{
566	disable_irq(ndev->irq);
567	nps_enet_irq_handler(ndev->irq, ndev);
568	enable_irq(ndev->irq);
569}
570#endif
571
572static const struct net_device_ops nps_netdev_ops = {
573	.ndo_open		= nps_enet_open,
574	.ndo_stop		= nps_enet_stop,
575	.ndo_start_xmit		= nps_enet_start_xmit,
576	.ndo_set_mac_address	= nps_enet_set_mac_address,
577	.ndo_set_rx_mode        = nps_enet_set_rx_mode,
578#ifdef CONFIG_NET_POLL_CONTROLLER
579	.ndo_poll_controller	= nps_enet_poll_controller,
580#endif
581};
582
583static s32 nps_enet_probe(struct platform_device *pdev)
584{
585	struct device *dev = &pdev->dev;
586	struct net_device *ndev;
587	struct nps_enet_priv *priv;
588	s32 err = 0;
589	const char *mac_addr;
590	struct resource *res_regs;
591
592	if (!dev->of_node)
593		return -ENODEV;
594
595	ndev = alloc_etherdev(sizeof(struct nps_enet_priv));
596	if (!ndev)
597		return -ENOMEM;
598
599	platform_set_drvdata(pdev, ndev);
600	SET_NETDEV_DEV(ndev, dev);
601	priv = netdev_priv(ndev);
602
603	/* The EZ NET specific entries in the device structure. */
604	ndev->netdev_ops = &nps_netdev_ops;
605	ndev->watchdog_timeo = (400 * HZ / 1000);
606	/* FIXME :: no multicast support yet */
607	ndev->flags &= ~IFF_MULTICAST;
608
609	res_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
610	priv->regs_base = devm_ioremap_resource(dev, res_regs);
611	if (IS_ERR(priv->regs_base)) {
612		err = PTR_ERR(priv->regs_base);
613		goto out_netdev;
614	}
615	dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs_base);
616
617	/* set kernel MAC address to dev */
618	mac_addr = of_get_mac_address(dev->of_node);
619	if (mac_addr)
620		ether_addr_copy(ndev->dev_addr, mac_addr);
621	else
622		eth_hw_addr_random(ndev);
623
624	/* Get IRQ number */
625	priv->irq = platform_get_irq(pdev, 0);
626	if (!priv->irq) {
627		dev_err(dev, "failed to retrieve <irq Rx-Tx> value from device tree\n");
628		err = -ENODEV;
629		goto out_netdev;
630	}
631
632	netif_napi_add(ndev, &priv->napi, nps_enet_poll,
633		       NPS_ENET_NAPI_POLL_WEIGHT);
634
635	/* Register the driver. Should be the last thing in probe */
636	err = register_netdev(ndev);
637	if (err) {
638		dev_err(dev, "Failed to register ndev for %s, err = 0x%08x\n",
639			ndev->name, (s32)err);
640		goto out_netif_api;
641	}
642
643	dev_info(dev, "(rx/tx=%d)\n", priv->irq);
644	return 0;
645
646out_netif_api:
647	netif_napi_del(&priv->napi);
648out_netdev:
649	if (err)
650		free_netdev(ndev);
651
652	return err;
653}
654
655static s32 nps_enet_remove(struct platform_device *pdev)
656{
657	struct net_device *ndev = platform_get_drvdata(pdev);
658	struct nps_enet_priv *priv = netdev_priv(ndev);
659
660	unregister_netdev(ndev);
661	free_netdev(ndev);
662	netif_napi_del(&priv->napi);
663
664	return 0;
665}
666
667static const struct of_device_id nps_enet_dt_ids[] = {
668	{ .compatible = "ezchip,nps-mgt-enet" },
669	{ /* Sentinel */ }
670};
671MODULE_DEVICE_TABLE(of, nps_enet_dt_ids);
672
673static struct platform_driver nps_enet_driver = {
674	.probe = nps_enet_probe,
675	.remove = nps_enet_remove,
676	.driver = {
677		.name = DRV_NAME,
678		.of_match_table  = nps_enet_dt_ids,
679	},
680};
681
682module_platform_driver(nps_enet_driver);
683
684MODULE_AUTHOR("EZchip Semiconductor");
685MODULE_LICENSE("GPL v2");