1// SPDX-License-Identifier: GPL-2.0-only
2/* drivers/net/ethernet/micrel/ks8851.c
3 *
4 * Copyright 2009 Simtec Electronics
5 *	http://www.simtec.co.uk/
6 *	Ben Dooks <ben@simtec.co.uk>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/interrupt.h>
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/netdevice.h>
15#include <linux/etherdevice.h>
16#include <linux/ethtool.h>
17#include <linux/cache.h>
18#include <linux/crc32.h>
19#include <linux/mii.h>
20#include <linux/regulator/consumer.h>
21
22#include <linux/spi/spi.h>
23#include <linux/gpio.h>
24#include <linux/of_gpio.h>
25#include <linux/of_net.h>
26
27#include "ks8851.h"
28
29static int msg_enable;
30
31/**
32 * struct ks8851_net_spi - KS8851 SPI driver private data
33 * @lock: Lock to ensure that the device is not accessed when busy.
34 * @tx_work: Work queue for tx packets
35 * @ks8851: KS8851 driver common private data
36 * @spidev: The spi device we're bound to.
37 * @spi_msg1: pre-setup SPI transfer with one message, @spi_xfer1.
38 * @spi_msg2: pre-setup SPI transfer with two messages, @spi_xfer2.
39 * @spi_xfer1: @spi_msg1 SPI transfer structure
40 * @spi_xfer2: @spi_msg2 SPI transfer structure
41 *
42 * The @lock ensures that the chip is protected when certain operations are
43 * in progress. When the read or write packet transfer is in progress, most
44 * of the chip registers are not ccessible until the transfer is finished and
45 * the DMA has been de-asserted.
46 */
47struct ks8851_net_spi {
48	struct ks8851_net	ks8851;
49	struct mutex		lock;
50	struct work_struct	tx_work;
51	struct spi_device	*spidev;
52	struct spi_message	spi_msg1;
53	struct spi_message	spi_msg2;
54	struct spi_transfer	spi_xfer1;
55	struct spi_transfer	spi_xfer2[2];
56};
57
58#define to_ks8851_spi(ks) container_of((ks), struct ks8851_net_spi, ks8851)
59
60/* SPI frame opcodes */
61#define KS_SPIOP_RD	0x00
62#define KS_SPIOP_WR	0x40
63#define KS_SPIOP_RXFIFO	0x80
64#define KS_SPIOP_TXFIFO	0xC0
65
66/* shift for byte-enable data */
67#define BYTE_EN(_x)	((_x) << 2)
68
69/* turn register number and byte-enable mask into data for start of packet */
70#define MK_OP(_byteen, _reg)	\
71	(BYTE_EN(_byteen) | (_reg) << (8 + 2) | (_reg) >> 6)
72
73/**
74 * ks8851_lock_spi - register access lock
75 * @ks: The chip state
76 * @flags: Spinlock flags
77 *
78 * Claim chip register access lock
79 */
80static void ks8851_lock_spi(struct ks8851_net *ks, unsigned long *flags)
81{
82	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
83
84	mutex_lock(&kss->lock);
85}
86
87/**
88 * ks8851_unlock_spi - register access unlock
89 * @ks: The chip state
90 * @flags: Spinlock flags
91 *
92 * Release chip register access lock
93 */
94static void ks8851_unlock_spi(struct ks8851_net *ks, unsigned long *flags)
95{
96	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
97
98	mutex_unlock(&kss->lock);
99}
100
101/* SPI register read/write calls.
102 *
103 * All these calls issue SPI transactions to access the chip's registers. They
104 * all require that the necessary lock is held to prevent accesses when the
105 * chip is busy transferring packet data (RX/TX FIFO accesses).
106 */
107
108/**
109 * ks8851_wrreg16_spi - write 16bit register value to chip via SPI
110 * @ks: The chip state
111 * @reg: The register address
112 * @val: The value to write
113 *
114 * Issue a write to put the value @val into the register specified in @reg.
115 */
116static void ks8851_wrreg16_spi(struct ks8851_net *ks, unsigned int reg,
117			       unsigned int val)
118{
119	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
120	struct spi_transfer *xfer = &kss->spi_xfer1;
121	struct spi_message *msg = &kss->spi_msg1;
122	__le16 txb[2];
123	int ret;
124
125	txb[0] = cpu_to_le16(MK_OP(reg & 2 ? 0xC : 0x03, reg) | KS_SPIOP_WR);
126	txb[1] = cpu_to_le16(val);
127
128	xfer->tx_buf = txb;
129	xfer->rx_buf = NULL;
130	xfer->len = 4;
131
132	ret = spi_sync(kss->spidev, msg);
133	if (ret < 0)
134		netdev_err(ks->netdev, "spi_sync() failed\n");
135}
136
137/**
138 * ks8851_rdreg - issue read register command and return the data
139 * @ks: The device state
140 * @op: The register address and byte enables in message format.
141 * @rxb: The RX buffer to return the result into
142 * @rxl: The length of data expected.
143 *
144 * This is the low level read call that issues the necessary spi message(s)
145 * to read data from the register specified in @op.
146 */
147static void ks8851_rdreg(struct ks8851_net *ks, unsigned int op,
148			 u8 *rxb, unsigned int rxl)
149{
150	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
151	struct spi_transfer *xfer;
152	struct spi_message *msg;
153	__le16 *txb = (__le16 *)ks->txd;
154	u8 *trx = ks->rxd;
155	int ret;
156
157	txb[0] = cpu_to_le16(op | KS_SPIOP_RD);
158
159	if (kss->spidev->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {
160		msg = &kss->spi_msg2;
161		xfer = kss->spi_xfer2;
162
163		xfer->tx_buf = txb;
164		xfer->rx_buf = NULL;
165		xfer->len = 2;
166
167		xfer++;
168		xfer->tx_buf = NULL;
169		xfer->rx_buf = trx;
170		xfer->len = rxl;
171	} else {
172		msg = &kss->spi_msg1;
173		xfer = &kss->spi_xfer1;
174
175		xfer->tx_buf = txb;
176		xfer->rx_buf = trx;
177		xfer->len = rxl + 2;
178	}
179
180	ret = spi_sync(kss->spidev, msg);
181	if (ret < 0)
182		netdev_err(ks->netdev, "read: spi_sync() failed\n");
183	else if (kss->spidev->controller->flags & SPI_CONTROLLER_HALF_DUPLEX)
184		memcpy(rxb, trx, rxl);
185	else
186		memcpy(rxb, trx + 2, rxl);
187}
188
189/**
190 * ks8851_rdreg16_spi - read 16 bit register from device via SPI
191 * @ks: The chip information
192 * @reg: The register address
193 *
194 * Read a 16bit register from the chip, returning the result
195 */
196static unsigned int ks8851_rdreg16_spi(struct ks8851_net *ks, unsigned int reg)
197{
198	__le16 rx = 0;
199
200	ks8851_rdreg(ks, MK_OP(reg & 2 ? 0xC : 0x3, reg), (u8 *)&rx, 2);
201	return le16_to_cpu(rx);
202}
203
204/**
205 * ks8851_rdfifo_spi - read data from the receive fifo via SPI
206 * @ks: The device state.
207 * @buff: The buffer address
208 * @len: The length of the data to read
209 *
210 * Issue an RXQ FIFO read command and read the @len amount of data from
211 * the FIFO into the buffer specified by @buff.
212 */
213static void ks8851_rdfifo_spi(struct ks8851_net *ks, u8 *buff, unsigned int len)
214{
215	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
216	struct spi_transfer *xfer = kss->spi_xfer2;
217	struct spi_message *msg = &kss->spi_msg2;
218	u8 txb[1];
219	int ret;
220
221	netif_dbg(ks, rx_status, ks->netdev,
222		  "%s: %d@%p\n", __func__, len, buff);
223
224	/* set the operation we're issuing */
225	txb[0] = KS_SPIOP_RXFIFO;
226
227	xfer->tx_buf = txb;
228	xfer->rx_buf = NULL;
229	xfer->len = 1;
230
231	xfer++;
232	xfer->rx_buf = buff;
233	xfer->tx_buf = NULL;
234	xfer->len = len;
235
236	ret = spi_sync(kss->spidev, msg);
237	if (ret < 0)
238		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
239}
240
241/**
242 * ks8851_wrfifo_spi - write packet to TX FIFO via SPI
243 * @ks: The device state.
244 * @txp: The sk_buff to transmit.
245 * @irq: IRQ on completion of the packet.
246 *
247 * Send the @txp to the chip. This means creating the relevant packet header
248 * specifying the length of the packet and the other information the chip
249 * needs, such as IRQ on completion. Send the header and the packet data to
250 * the device.
251 */
252static void ks8851_wrfifo_spi(struct ks8851_net *ks, struct sk_buff *txp,
253			      bool irq)
254{
255	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
256	struct spi_transfer *xfer = kss->spi_xfer2;
257	struct spi_message *msg = &kss->spi_msg2;
258	unsigned int fid = 0;
259	int ret;
260
261	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
262		  __func__, txp, txp->len, txp->data, irq);
263
264	fid = ks->fid++;
265	fid &= TXFR_TXFID_MASK;
266
267	if (irq)
268		fid |= TXFR_TXIC;	/* irq on completion */
269
270	/* start header at txb[1] to align txw entries */
271	ks->txh.txb[1] = KS_SPIOP_TXFIFO;
272	ks->txh.txw[1] = cpu_to_le16(fid);
273	ks->txh.txw[2] = cpu_to_le16(txp->len);
274
275	xfer->tx_buf = &ks->txh.txb[1];
276	xfer->rx_buf = NULL;
277	xfer->len = 5;
278
279	xfer++;
280	xfer->tx_buf = txp->data;
281	xfer->rx_buf = NULL;
282	xfer->len = ALIGN(txp->len, 4);
283
284	ret = spi_sync(kss->spidev, msg);
285	if (ret < 0)
286		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
287}
288
289/**
290 * calc_txlen - calculate size of message to send packet
291 * @len: Length of data
292 *
293 * Returns the size of the TXFIFO message needed to send
294 * this packet.
295 */
296static unsigned int calc_txlen(unsigned int len)
297{
298	return ALIGN(len + 4, 4);
299}
300
301/**
302 * ks8851_tx_work - process tx packet(s)
303 * @work: The work strucutre what was scheduled.
304 *
305 * This is called when a number of packets have been scheduled for
306 * transmission and need to be sent to the device.
307 */
308static void ks8851_tx_work(struct work_struct *work)
309{
310	unsigned int dequeued_len = 0;
311	struct ks8851_net_spi *kss;
312	unsigned short tx_space;
313	struct ks8851_net *ks;
314	unsigned long flags;
315	struct sk_buff *txb;
316	bool last;
317
318	kss = container_of(work, struct ks8851_net_spi, tx_work);
319	ks = &kss->ks8851;
320	last = skb_queue_empty(&ks->txq);
321
322	ks8851_lock_spi(ks, &flags);
323
324	while (!last) {
325		txb = skb_dequeue(&ks->txq);
326		last = skb_queue_empty(&ks->txq);
327
328		if (txb) {
329			dequeued_len += calc_txlen(txb->len);
330
331			ks8851_wrreg16_spi(ks, KS_RXQCR,
332					   ks->rc_rxqcr | RXQCR_SDA);
333			ks8851_wrfifo_spi(ks, txb, last);
334			ks8851_wrreg16_spi(ks, KS_RXQCR, ks->rc_rxqcr);
335			ks8851_wrreg16_spi(ks, KS_TXQCR, TXQCR_METFE);
336
337			ks8851_done_tx(ks, txb);
338		}
339	}
340
341	tx_space = ks8851_rdreg16_spi(ks, KS_TXMIR);
342
343	spin_lock(&ks->statelock);
344	ks->queued_len -= dequeued_len;
345	ks->tx_space = tx_space;
346	spin_unlock(&ks->statelock);
347
348	ks8851_unlock_spi(ks, &flags);
349}
350
351/**
352 * ks8851_flush_tx_work_spi - flush outstanding TX work
353 * @ks: The device state
354 */
355static void ks8851_flush_tx_work_spi(struct ks8851_net *ks)
356{
357	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
358
359	flush_work(&kss->tx_work);
360}
361
362/**
363 * ks8851_start_xmit_spi - transmit packet using SPI
364 * @skb: The buffer to transmit
365 * @dev: The device used to transmit the packet.
366 *
367 * Called by the network layer to transmit the @skb. Queue the packet for
368 * the device and schedule the necessary work to transmit the packet when
369 * it is free.
370 *
371 * We do this to firstly avoid sleeping with the network device locked,
372 * and secondly so we can round up more than one packet to transmit which
373 * means we can try and avoid generating too many transmit done interrupts.
374 */
375static netdev_tx_t ks8851_start_xmit_spi(struct sk_buff *skb,
376					 struct net_device *dev)
377{
378	unsigned int needed = calc_txlen(skb->len);
379	struct ks8851_net *ks = netdev_priv(dev);
380	netdev_tx_t ret = NETDEV_TX_OK;
381	struct ks8851_net_spi *kss;
382
383	kss = to_ks8851_spi(ks);
384
385	netif_dbg(ks, tx_queued, ks->netdev,
386		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);
387
388	spin_lock(&ks->statelock);
389
390	if (ks->queued_len + needed > ks->tx_space) {
391		netif_stop_queue(dev);
392		ret = NETDEV_TX_BUSY;
393	} else {
394		ks->queued_len += needed;
395		skb_queue_tail(&ks->txq, skb);
396	}
397
398	spin_unlock(&ks->statelock);
399	if (ret == NETDEV_TX_OK)
400		schedule_work(&kss->tx_work);
401
402	return ret;
403}
404
405static int ks8851_probe_spi(struct spi_device *spi)
406{
407	struct device *dev = &spi->dev;
408	struct ks8851_net_spi *kss;
409	struct net_device *netdev;
410	struct ks8851_net *ks;
411
412	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_spi));
413	if (!netdev)
414		return -ENOMEM;
415
416	spi->bits_per_word = 8;
417
418	kss = netdev_priv(netdev);
419	ks = &kss->ks8851;
420
421	ks->lock = ks8851_lock_spi;
422	ks->unlock = ks8851_unlock_spi;
423	ks->rdreg16 = ks8851_rdreg16_spi;
424	ks->wrreg16 = ks8851_wrreg16_spi;
425	ks->rdfifo = ks8851_rdfifo_spi;
426	ks->wrfifo = ks8851_wrfifo_spi;
427	ks->start_xmit = ks8851_start_xmit_spi;
428	ks->flush_tx_work = ks8851_flush_tx_work_spi;
429
430#define STD_IRQ (IRQ_LCI |	/* Link Change */	\
431		 IRQ_TXI |	/* TX done */		\
432		 IRQ_RXI |	/* RX done */		\
433		 IRQ_SPIBEI |	/* SPI bus error */	\
434		 IRQ_TXPSI |	/* TX process stop */	\
435		 IRQ_RXPSI)	/* RX process stop */
436	ks->rc_ier = STD_IRQ;
437
438	kss->spidev = spi;
439	mutex_init(&kss->lock);
440	INIT_WORK(&kss->tx_work, ks8851_tx_work);
441
442	/* initialise pre-made spi transfer messages */
443	spi_message_init(&kss->spi_msg1);
444	spi_message_add_tail(&kss->spi_xfer1, &kss->spi_msg1);
445
446	spi_message_init(&kss->spi_msg2);
447	spi_message_add_tail(&kss->spi_xfer2[0], &kss->spi_msg2);
448	spi_message_add_tail(&kss->spi_xfer2[1], &kss->spi_msg2);
449
450	netdev->irq = spi->irq;
451
452	return ks8851_probe_common(netdev, dev, msg_enable);
453}
454
455static void ks8851_remove_spi(struct spi_device *spi)
456{
457	ks8851_remove_common(&spi->dev);
458}
459
460static const struct of_device_id ks8851_match_table[] = {
461	{ .compatible = "micrel,ks8851" },
462	{ }
463};
464MODULE_DEVICE_TABLE(of, ks8851_match_table);
465
466static struct spi_driver ks8851_driver = {
467	.driver = {
468		.name = "ks8851",
469		.of_match_table = ks8851_match_table,
470		.pm = &ks8851_pm_ops,
471	},
472	.probe = ks8851_probe_spi,
473	.remove = ks8851_remove_spi,
474};
475module_spi_driver(ks8851_driver);
476
477MODULE_DESCRIPTION("KS8851 Network driver");
478MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
479MODULE_LICENSE("GPL");
480
481module_param_named(message, msg_enable, int, 0);
482MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
483MODULE_ALIAS("spi:ks8851");
484