1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Altera TSE SGDMA and MSGDMA Linux driver
3  * Copyright (C) 2014 Altera Corporation. All rights reserved
4  */
5 
6 #include <linux/list.h>
7 #include "altera_utils.h"
8 #include "altera_tse.h"
9 #include "altera_sgdmahw.h"
10 #include "altera_sgdma.h"
11 
12 static void sgdma_setup_descrip(struct sgdma_descrip __iomem *desc,
13 				struct sgdma_descrip __iomem *ndesc,
14 				dma_addr_t ndesc_phys,
15 				dma_addr_t raddr,
16 				dma_addr_t waddr,
17 				u16 length,
18 				int generate_eop,
19 				int rfixed,
20 				int wfixed);
21 
22 static int sgdma_async_write(struct altera_tse_private *priv,
23 			      struct sgdma_descrip __iomem *desc);
24 
25 static int sgdma_async_read(struct altera_tse_private *priv);
26 
27 static dma_addr_t
28 sgdma_txphysaddr(struct altera_tse_private *priv,
29 		 struct sgdma_descrip __iomem *desc);
30 
31 static dma_addr_t
32 sgdma_rxphysaddr(struct altera_tse_private *priv,
33 		 struct sgdma_descrip __iomem *desc);
34 
35 static int sgdma_txbusy(struct altera_tse_private *priv);
36 
37 static int sgdma_rxbusy(struct altera_tse_private *priv);
38 
39 static void
40 queue_tx(struct altera_tse_private *priv, struct tse_buffer *buffer);
41 
42 static void
43 queue_rx(struct altera_tse_private *priv, struct tse_buffer *buffer);
44 
45 static struct tse_buffer *
46 dequeue_tx(struct altera_tse_private *priv);
47 
48 static struct tse_buffer *
49 dequeue_rx(struct altera_tse_private *priv);
50 
51 static struct tse_buffer *
52 queue_rx_peekhead(struct altera_tse_private *priv);
53 
sgdma_initialize(struct altera_tse_private * priv)54 int sgdma_initialize(struct altera_tse_private *priv)
55 {
56 	priv->txctrlreg = SGDMA_CTRLREG_ILASTD |
57 		      SGDMA_CTRLREG_INTEN;
58 
59 	priv->rxctrlreg = SGDMA_CTRLREG_IDESCRIP |
60 		      SGDMA_CTRLREG_INTEN |
61 		      SGDMA_CTRLREG_ILASTD;
62 
63 	INIT_LIST_HEAD(&priv->txlisthd);
64 	INIT_LIST_HEAD(&priv->rxlisthd);
65 
66 	priv->rxdescphys = (dma_addr_t) 0;
67 	priv->txdescphys = (dma_addr_t) 0;
68 
69 	priv->rxdescphys = dma_map_single(priv->device,
70 					  (void __force *)priv->rx_dma_desc,
71 					  priv->rxdescmem, DMA_BIDIRECTIONAL);
72 
73 	if (dma_mapping_error(priv->device, priv->rxdescphys)) {
74 		sgdma_uninitialize(priv);
75 		netdev_err(priv->dev, "error mapping rx descriptor memory\n");
76 		return -EINVAL;
77 	}
78 
79 	priv->txdescphys = dma_map_single(priv->device,
80 					  (void __force *)priv->tx_dma_desc,
81 					  priv->txdescmem, DMA_TO_DEVICE);
82 
83 	if (dma_mapping_error(priv->device, priv->txdescphys)) {
84 		sgdma_uninitialize(priv);
85 		netdev_err(priv->dev, "error mapping tx descriptor memory\n");
86 		return -EINVAL;
87 	}
88 
89 	/* Initialize descriptor memory to all 0's, sync memory to cache */
90 	memset_io(priv->tx_dma_desc, 0, priv->txdescmem);
91 	memset_io(priv->rx_dma_desc, 0, priv->rxdescmem);
92 
93 	dma_sync_single_for_device(priv->device, priv->txdescphys,
94 				   priv->txdescmem, DMA_TO_DEVICE);
95 
96 	dma_sync_single_for_device(priv->device, priv->rxdescphys,
97 				   priv->rxdescmem, DMA_TO_DEVICE);
98 
99 	return 0;
100 }
101 
sgdma_uninitialize(struct altera_tse_private * priv)102 void sgdma_uninitialize(struct altera_tse_private *priv)
103 {
104 	if (priv->rxdescphys)
105 		dma_unmap_single(priv->device, priv->rxdescphys,
106 				 priv->rxdescmem, DMA_BIDIRECTIONAL);
107 
108 	if (priv->txdescphys)
109 		dma_unmap_single(priv->device, priv->txdescphys,
110 				 priv->txdescmem, DMA_TO_DEVICE);
111 }
112 
113 /* This function resets the SGDMA controller and clears the
114  * descriptor memory used for transmits and receives.
115  */
sgdma_reset(struct altera_tse_private * priv)116 void sgdma_reset(struct altera_tse_private *priv)
117 {
118 	/* Initialize descriptor memory to 0 */
119 	memset_io(priv->tx_dma_desc, 0, priv->txdescmem);
120 	memset_io(priv->rx_dma_desc, 0, priv->rxdescmem);
121 
122 	csrwr32(SGDMA_CTRLREG_RESET, priv->tx_dma_csr, sgdma_csroffs(control));
123 	csrwr32(0, priv->tx_dma_csr, sgdma_csroffs(control));
124 
125 	csrwr32(SGDMA_CTRLREG_RESET, priv->rx_dma_csr, sgdma_csroffs(control));
126 	csrwr32(0, priv->rx_dma_csr, sgdma_csroffs(control));
127 }
128 
129 /* For SGDMA, interrupts remain enabled after initially enabling,
130  * so no need to provide implementations for abstract enable
131  * and disable
132  */
133 
sgdma_enable_rxirq(struct altera_tse_private * priv)134 void sgdma_enable_rxirq(struct altera_tse_private *priv)
135 {
136 }
137 
sgdma_enable_txirq(struct altera_tse_private * priv)138 void sgdma_enable_txirq(struct altera_tse_private *priv)
139 {
140 }
141 
sgdma_disable_rxirq(struct altera_tse_private * priv)142 void sgdma_disable_rxirq(struct altera_tse_private *priv)
143 {
144 }
145 
sgdma_disable_txirq(struct altera_tse_private * priv)146 void sgdma_disable_txirq(struct altera_tse_private *priv)
147 {
148 }
149 
sgdma_clear_rxirq(struct altera_tse_private * priv)150 void sgdma_clear_rxirq(struct altera_tse_private *priv)
151 {
152 	tse_set_bit(priv->rx_dma_csr, sgdma_csroffs(control),
153 		    SGDMA_CTRLREG_CLRINT);
154 }
155 
sgdma_clear_txirq(struct altera_tse_private * priv)156 void sgdma_clear_txirq(struct altera_tse_private *priv)
157 {
158 	tse_set_bit(priv->tx_dma_csr, sgdma_csroffs(control),
159 		    SGDMA_CTRLREG_CLRINT);
160 }
161 
162 /* transmits buffer through SGDMA. Returns number of buffers
163  * transmitted, 0 if not possible.
164  *
165  * tx_lock is held by the caller
166  */
sgdma_tx_buffer(struct altera_tse_private * priv,struct tse_buffer * buffer)167 int sgdma_tx_buffer(struct altera_tse_private *priv, struct tse_buffer *buffer)
168 {
169 	struct sgdma_descrip __iomem *descbase =
170 		(struct sgdma_descrip __iomem *)priv->tx_dma_desc;
171 
172 	struct sgdma_descrip __iomem *cdesc = &descbase[0];
173 	struct sgdma_descrip __iomem *ndesc = &descbase[1];
174 
175 	/* wait 'til the tx sgdma is ready for the next transmit request */
176 	if (sgdma_txbusy(priv))
177 		return 0;
178 
179 	sgdma_setup_descrip(cdesc,			/* current descriptor */
180 			    ndesc,			/* next descriptor */
181 			    sgdma_txphysaddr(priv, ndesc),
182 			    buffer->dma_addr,		/* address of packet to xmit */
183 			    0,				/* write addr 0 for tx dma */
184 			    buffer->len,		/* length of packet */
185 			    SGDMA_CONTROL_EOP,		/* Generate EOP */
186 			    0,				/* read fixed */
187 			    SGDMA_CONTROL_WR_FIXED);	/* Generate SOP */
188 
189 	sgdma_async_write(priv, cdesc);
190 
191 	/* enqueue the request to the pending transmit queue */
192 	queue_tx(priv, buffer);
193 
194 	return 1;
195 }
196 
197 
198 /* tx_lock held to protect access to queued tx list
199  */
sgdma_tx_completions(struct altera_tse_private * priv)200 u32 sgdma_tx_completions(struct altera_tse_private *priv)
201 {
202 	u32 ready = 0;
203 
204 	if (!sgdma_txbusy(priv) &&
205 	    ((csrrd8(priv->tx_dma_desc, sgdma_descroffs(control))
206 	     & SGDMA_CONTROL_HW_OWNED) == 0) &&
207 	    (dequeue_tx(priv))) {
208 		ready = 1;
209 	}
210 
211 	return ready;
212 }
213 
sgdma_start_rxdma(struct altera_tse_private * priv)214 void sgdma_start_rxdma(struct altera_tse_private *priv)
215 {
216 	sgdma_async_read(priv);
217 }
218 
sgdma_add_rx_desc(struct altera_tse_private * priv,struct tse_buffer * rxbuffer)219 void sgdma_add_rx_desc(struct altera_tse_private *priv,
220 		       struct tse_buffer *rxbuffer)
221 {
222 	queue_rx(priv, rxbuffer);
223 }
224 
225 /* status is returned on upper 16 bits,
226  * length is returned in lower 16 bits
227  */
sgdma_rx_status(struct altera_tse_private * priv)228 u32 sgdma_rx_status(struct altera_tse_private *priv)
229 {
230 	struct sgdma_descrip __iomem *base =
231 		(struct sgdma_descrip __iomem *)priv->rx_dma_desc;
232 	struct sgdma_descrip __iomem *desc = NULL;
233 	struct tse_buffer *rxbuffer = NULL;
234 	unsigned int rxstatus = 0;
235 
236 	u32 sts = csrrd32(priv->rx_dma_csr, sgdma_csroffs(status));
237 
238 	desc = &base[0];
239 	if (sts & SGDMA_STSREG_EOP) {
240 		unsigned int pktlength = 0;
241 		unsigned int pktstatus = 0;
242 		dma_sync_single_for_cpu(priv->device,
243 					priv->rxdescphys,
244 					SGDMA_DESC_LEN,
245 					DMA_FROM_DEVICE);
246 
247 		pktlength = csrrd16(desc, sgdma_descroffs(bytes_xferred));
248 		pktstatus = csrrd8(desc, sgdma_descroffs(status));
249 		rxstatus = pktstatus & ~SGDMA_STATUS_EOP;
250 		rxstatus = rxstatus << 16;
251 		rxstatus |= (pktlength & 0xffff);
252 
253 		if (rxstatus) {
254 			csrwr8(0, desc, sgdma_descroffs(status));
255 
256 			rxbuffer = dequeue_rx(priv);
257 			if (rxbuffer == NULL)
258 				netdev_info(priv->dev,
259 					    "sgdma rx and rx queue empty!\n");
260 
261 			/* Clear control */
262 			csrwr32(0, priv->rx_dma_csr, sgdma_csroffs(control));
263 			/* clear status */
264 			csrwr32(0xf, priv->rx_dma_csr, sgdma_csroffs(status));
265 
266 			/* kick the rx sgdma after reaping this descriptor */
267 			sgdma_async_read(priv);
268 
269 		} else {
270 			/* If the SGDMA indicated an end of packet on recv,
271 			 * then it's expected that the rxstatus from the
272 			 * descriptor is non-zero - meaning a valid packet
273 			 * with a nonzero length, or an error has been
274 			 * indicated. if not, then all we can do is signal
275 			 * an error and return no packet received. Most likely
276 			 * there is a system design error, or an error in the
277 			 * underlying kernel (cache or cache management problem)
278 			 */
279 			netdev_err(priv->dev,
280 				   "SGDMA RX Error Info: %x, %x, %x\n",
281 				   sts, csrrd8(desc, sgdma_descroffs(status)),
282 				   rxstatus);
283 		}
284 	} else if (sts == 0) {
285 		sgdma_async_read(priv);
286 	}
287 
288 	return rxstatus;
289 }
290 
291 
292 /* Private functions */
sgdma_setup_descrip(struct sgdma_descrip __iomem * desc,struct sgdma_descrip __iomem * ndesc,dma_addr_t ndesc_phys,dma_addr_t raddr,dma_addr_t waddr,u16 length,int generate_eop,int rfixed,int wfixed)293 static void sgdma_setup_descrip(struct sgdma_descrip __iomem *desc,
294 				struct sgdma_descrip __iomem *ndesc,
295 				dma_addr_t ndesc_phys,
296 				dma_addr_t raddr,
297 				dma_addr_t waddr,
298 				u16 length,
299 				int generate_eop,
300 				int rfixed,
301 				int wfixed)
302 {
303 	/* Clear the next descriptor as not owned by hardware */
304 
305 	u32 ctrl = csrrd8(ndesc, sgdma_descroffs(control));
306 	ctrl &= ~SGDMA_CONTROL_HW_OWNED;
307 	csrwr8(ctrl, ndesc, sgdma_descroffs(control));
308 
309 	ctrl = SGDMA_CONTROL_HW_OWNED;
310 	ctrl |= generate_eop;
311 	ctrl |= rfixed;
312 	ctrl |= wfixed;
313 
314 	/* Channel is implicitly zero, initialized to 0 by default */
315 	csrwr32(lower_32_bits(raddr), desc, sgdma_descroffs(raddr));
316 	csrwr32(lower_32_bits(waddr), desc, sgdma_descroffs(waddr));
317 
318 	csrwr32(0, desc, sgdma_descroffs(pad1));
319 	csrwr32(0, desc, sgdma_descroffs(pad2));
320 	csrwr32(lower_32_bits(ndesc_phys), desc, sgdma_descroffs(next));
321 
322 	csrwr8(ctrl, desc, sgdma_descroffs(control));
323 	csrwr8(0, desc, sgdma_descroffs(status));
324 	csrwr8(0, desc, sgdma_descroffs(wburst));
325 	csrwr8(0, desc, sgdma_descroffs(rburst));
326 	csrwr16(length, desc, sgdma_descroffs(bytes));
327 	csrwr16(0, desc, sgdma_descroffs(bytes_xferred));
328 }
329 
330 /* If hardware is busy, don't restart async read.
331  * if status register is 0 - meaning initial state, restart async read,
332  * probably for the first time when populating a receive buffer.
333  * If read status indicate not busy and a status, restart the async
334  * DMA read.
335  */
sgdma_async_read(struct altera_tse_private * priv)336 static int sgdma_async_read(struct altera_tse_private *priv)
337 {
338 	struct sgdma_descrip __iomem *descbase =
339 		(struct sgdma_descrip __iomem *)priv->rx_dma_desc;
340 
341 	struct sgdma_descrip __iomem *cdesc = &descbase[0];
342 	struct sgdma_descrip __iomem *ndesc = &descbase[1];
343 	struct tse_buffer *rxbuffer = NULL;
344 
345 	if (!sgdma_rxbusy(priv)) {
346 		rxbuffer = queue_rx_peekhead(priv);
347 		if (rxbuffer == NULL) {
348 			netdev_err(priv->dev, "no rx buffers available\n");
349 			return 0;
350 		}
351 
352 		sgdma_setup_descrip(cdesc,		/* current descriptor */
353 				    ndesc,		/* next descriptor */
354 				    sgdma_rxphysaddr(priv, ndesc),
355 				    0,			/* read addr 0 for rx dma */
356 				    rxbuffer->dma_addr, /* write addr for rx dma */
357 				    0,			/* read 'til EOP */
358 				    0,			/* EOP: NA for rx dma */
359 				    0,			/* read fixed: NA for rx dma */
360 				    0);			/* SOP: NA for rx DMA */
361 
362 		dma_sync_single_for_device(priv->device,
363 					   priv->rxdescphys,
364 					   SGDMA_DESC_LEN,
365 					   DMA_TO_DEVICE);
366 
367 		csrwr32(lower_32_bits(sgdma_rxphysaddr(priv, cdesc)),
368 			priv->rx_dma_csr,
369 			sgdma_csroffs(next_descrip));
370 
371 		csrwr32((priv->rxctrlreg | SGDMA_CTRLREG_START),
372 			priv->rx_dma_csr,
373 			sgdma_csroffs(control));
374 
375 		return 1;
376 	}
377 
378 	return 0;
379 }
380 
sgdma_async_write(struct altera_tse_private * priv,struct sgdma_descrip __iomem * desc)381 static int sgdma_async_write(struct altera_tse_private *priv,
382 			     struct sgdma_descrip __iomem *desc)
383 {
384 	if (sgdma_txbusy(priv))
385 		return 0;
386 
387 	/* clear control and status */
388 	csrwr32(0, priv->tx_dma_csr, sgdma_csroffs(control));
389 	csrwr32(0x1f, priv->tx_dma_csr, sgdma_csroffs(status));
390 
391 	dma_sync_single_for_device(priv->device, priv->txdescphys,
392 				   SGDMA_DESC_LEN, DMA_TO_DEVICE);
393 
394 	csrwr32(lower_32_bits(sgdma_txphysaddr(priv, desc)),
395 		priv->tx_dma_csr,
396 		sgdma_csroffs(next_descrip));
397 
398 	csrwr32((priv->txctrlreg | SGDMA_CTRLREG_START),
399 		priv->tx_dma_csr,
400 		sgdma_csroffs(control));
401 
402 	return 1;
403 }
404 
405 static dma_addr_t
sgdma_txphysaddr(struct altera_tse_private * priv,struct sgdma_descrip __iomem * desc)406 sgdma_txphysaddr(struct altera_tse_private *priv,
407 		 struct sgdma_descrip __iomem *desc)
408 {
409 	dma_addr_t paddr = priv->txdescmem_busaddr;
410 	uintptr_t offs = (uintptr_t)desc - (uintptr_t)priv->tx_dma_desc;
411 	return (dma_addr_t)((uintptr_t)paddr + offs);
412 }
413 
414 static dma_addr_t
sgdma_rxphysaddr(struct altera_tse_private * priv,struct sgdma_descrip __iomem * desc)415 sgdma_rxphysaddr(struct altera_tse_private *priv,
416 		 struct sgdma_descrip __iomem *desc)
417 {
418 	dma_addr_t paddr = priv->rxdescmem_busaddr;
419 	uintptr_t offs = (uintptr_t)desc - (uintptr_t)priv->rx_dma_desc;
420 	return (dma_addr_t)((uintptr_t)paddr + offs);
421 }
422 
423 #define list_remove_head(list, entry, type, member)			\
424 	do {								\
425 		entry = NULL;						\
426 		if (!list_empty(list)) {				\
427 			entry = list_entry((list)->next, type, member);	\
428 			list_del_init(&entry->member);			\
429 		}							\
430 	} while (0)
431 
432 #define list_peek_head(list, entry, type, member)			\
433 	do {								\
434 		entry = NULL;						\
435 		if (!list_empty(list)) {				\
436 			entry = list_entry((list)->next, type, member);	\
437 		}							\
438 	} while (0)
439 
440 /* adds a tse_buffer to the tail of a tx buffer list.
441  * assumes the caller is managing and holding a mutual exclusion
442  * primitive to avoid simultaneous pushes/pops to the list.
443  */
444 static void
queue_tx(struct altera_tse_private * priv,struct tse_buffer * buffer)445 queue_tx(struct altera_tse_private *priv, struct tse_buffer *buffer)
446 {
447 	list_add_tail(&buffer->lh, &priv->txlisthd);
448 }
449 
450 
451 /* adds a tse_buffer to the tail of a rx buffer list
452  * assumes the caller is managing and holding a mutual exclusion
453  * primitive to avoid simultaneous pushes/pops to the list.
454  */
455 static void
queue_rx(struct altera_tse_private * priv,struct tse_buffer * buffer)456 queue_rx(struct altera_tse_private *priv, struct tse_buffer *buffer)
457 {
458 	list_add_tail(&buffer->lh, &priv->rxlisthd);
459 }
460 
461 /* dequeues a tse_buffer from the transmit buffer list, otherwise
462  * returns NULL if empty.
463  * assumes the caller is managing and holding a mutual exclusion
464  * primitive to avoid simultaneous pushes/pops to the list.
465  */
466 static struct tse_buffer *
dequeue_tx(struct altera_tse_private * priv)467 dequeue_tx(struct altera_tse_private *priv)
468 {
469 	struct tse_buffer *buffer = NULL;
470 	list_remove_head(&priv->txlisthd, buffer, struct tse_buffer, lh);
471 	return buffer;
472 }
473 
474 /* dequeues a tse_buffer from the receive buffer list, otherwise
475  * returns NULL if empty
476  * assumes the caller is managing and holding a mutual exclusion
477  * primitive to avoid simultaneous pushes/pops to the list.
478  */
479 static struct tse_buffer *
dequeue_rx(struct altera_tse_private * priv)480 dequeue_rx(struct altera_tse_private *priv)
481 {
482 	struct tse_buffer *buffer = NULL;
483 	list_remove_head(&priv->rxlisthd, buffer, struct tse_buffer, lh);
484 	return buffer;
485 }
486 
487 /* dequeues a tse_buffer from the receive buffer list, otherwise
488  * returns NULL if empty
489  * assumes the caller is managing and holding a mutual exclusion
490  * primitive to avoid simultaneous pushes/pops to the list while the
491  * head is being examined.
492  */
493 static struct tse_buffer *
queue_rx_peekhead(struct altera_tse_private * priv)494 queue_rx_peekhead(struct altera_tse_private *priv)
495 {
496 	struct tse_buffer *buffer = NULL;
497 	list_peek_head(&priv->rxlisthd, buffer, struct tse_buffer, lh);
498 	return buffer;
499 }
500 
501 /* check and return rx sgdma status without polling
502  */
sgdma_rxbusy(struct altera_tse_private * priv)503 static int sgdma_rxbusy(struct altera_tse_private *priv)
504 {
505 	return csrrd32(priv->rx_dma_csr, sgdma_csroffs(status))
506 		       & SGDMA_STSREG_BUSY;
507 }
508 
509 /* waits for the tx sgdma to finish it's current operation, returns 0
510  * when it transitions to nonbusy, returns 1 if the operation times out
511  */
sgdma_txbusy(struct altera_tse_private * priv)512 static int sgdma_txbusy(struct altera_tse_private *priv)
513 {
514 	int delay = 0;
515 
516 	/* if DMA is busy, wait for current transaction to finish */
517 	while ((csrrd32(priv->tx_dma_csr, sgdma_csroffs(status))
518 		& SGDMA_STSREG_BUSY) && (delay++ < 100))
519 		udelay(1);
520 
521 	if (csrrd32(priv->tx_dma_csr, sgdma_csroffs(status))
522 	    & SGDMA_STSREG_BUSY) {
523 		netdev_err(priv->dev, "timeout waiting for tx dma\n");
524 		return 1;
525 	}
526 	return 0;
527 }
528