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 
29 static 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  */
47 struct 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  */
80 static 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  */
94 static 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  */
116 static 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  */
147 static 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->master->flags & SPI_MASTER_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->master->flags & SPI_MASTER_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  */
196 static 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  */
213 static 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  */
252 static 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  */
296 static 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  */
308 static 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  */
355 static 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  */
375 static 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 
405 static 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 
455 static void ks8851_remove_spi(struct spi_device *spi)
456 {
457 	ks8851_remove_common(&spi->dev);
458 }
459 
460 static const struct of_device_id ks8851_match_table[] = {
461 	{ .compatible = "micrel,ks8851" },
462 	{ }
463 };
464 MODULE_DEVICE_TABLE(of, ks8851_match_table);
465 
466 static 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 };
475 module_spi_driver(ks8851_driver);
476 
477 MODULE_DESCRIPTION("KS8851 Network driver");
478 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
479 MODULE_LICENSE("GPL");
480 
481 module_param_named(message, msg_enable, int, 0);
482 MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
483 MODULE_ALIAS("spi:ks8851");
484