1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * SPI-Engine SPI controller driver
4  * Copyright 2015 Analog Devices Inc.
5  *  Author: Lars-Peter Clausen <lars@metafoo.de>
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/interrupt.h>
10 #include <linux/io.h>
11 #include <linux/of.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/spi/spi.h>
15 
16 #define SPI_ENGINE_VERSION_MAJOR(x)	((x >> 16) & 0xff)
17 #define SPI_ENGINE_VERSION_MINOR(x)	((x >> 8) & 0xff)
18 #define SPI_ENGINE_VERSION_PATCH(x)	(x & 0xff)
19 
20 #define SPI_ENGINE_REG_VERSION			0x00
21 
22 #define SPI_ENGINE_REG_RESET			0x40
23 
24 #define SPI_ENGINE_REG_INT_ENABLE		0x80
25 #define SPI_ENGINE_REG_INT_PENDING		0x84
26 #define SPI_ENGINE_REG_INT_SOURCE		0x88
27 
28 #define SPI_ENGINE_REG_SYNC_ID			0xc0
29 
30 #define SPI_ENGINE_REG_CMD_FIFO_ROOM		0xd0
31 #define SPI_ENGINE_REG_SDO_FIFO_ROOM		0xd4
32 #define SPI_ENGINE_REG_SDI_FIFO_LEVEL		0xd8
33 
34 #define SPI_ENGINE_REG_CMD_FIFO			0xe0
35 #define SPI_ENGINE_REG_SDO_DATA_FIFO		0xe4
36 #define SPI_ENGINE_REG_SDI_DATA_FIFO		0xe8
37 #define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK	0xec
38 
39 #define SPI_ENGINE_INT_CMD_ALMOST_EMPTY		BIT(0)
40 #define SPI_ENGINE_INT_SDO_ALMOST_EMPTY		BIT(1)
41 #define SPI_ENGINE_INT_SDI_ALMOST_FULL		BIT(2)
42 #define SPI_ENGINE_INT_SYNC			BIT(3)
43 
44 #define SPI_ENGINE_CONFIG_CPHA			BIT(0)
45 #define SPI_ENGINE_CONFIG_CPOL			BIT(1)
46 #define SPI_ENGINE_CONFIG_3WIRE			BIT(2)
47 
48 #define SPI_ENGINE_INST_TRANSFER		0x0
49 #define SPI_ENGINE_INST_ASSERT			0x1
50 #define SPI_ENGINE_INST_WRITE			0x2
51 #define SPI_ENGINE_INST_MISC			0x3
52 
53 #define SPI_ENGINE_CMD_REG_CLK_DIV		0x0
54 #define SPI_ENGINE_CMD_REG_CONFIG		0x1
55 
56 #define SPI_ENGINE_MISC_SYNC			0x0
57 #define SPI_ENGINE_MISC_SLEEP			0x1
58 
59 #define SPI_ENGINE_TRANSFER_WRITE		0x1
60 #define SPI_ENGINE_TRANSFER_READ		0x2
61 
62 #define SPI_ENGINE_CMD(inst, arg1, arg2) \
63 	(((inst) << 12) | ((arg1) << 8) | (arg2))
64 
65 #define SPI_ENGINE_CMD_TRANSFER(flags, n) \
66 	SPI_ENGINE_CMD(SPI_ENGINE_INST_TRANSFER, (flags), (n))
67 #define SPI_ENGINE_CMD_ASSERT(delay, cs) \
68 	SPI_ENGINE_CMD(SPI_ENGINE_INST_ASSERT, (delay), (cs))
69 #define SPI_ENGINE_CMD_WRITE(reg, val) \
70 	SPI_ENGINE_CMD(SPI_ENGINE_INST_WRITE, (reg), (val))
71 #define SPI_ENGINE_CMD_SLEEP(delay) \
72 	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SLEEP, (delay))
73 #define SPI_ENGINE_CMD_SYNC(id) \
74 	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SYNC, (id))
75 
76 struct spi_engine_program {
77 	unsigned int length;
78 	uint16_t instructions[];
79 };
80 
81 struct spi_engine {
82 	struct clk *clk;
83 	struct clk *ref_clk;
84 
85 	spinlock_t lock;
86 
87 	void __iomem *base;
88 
89 	struct spi_message *msg;
90 	struct spi_engine_program *p;
91 	unsigned cmd_length;
92 	const uint16_t *cmd_buf;
93 
94 	struct spi_transfer *tx_xfer;
95 	unsigned int tx_length;
96 	const uint8_t *tx_buf;
97 
98 	struct spi_transfer *rx_xfer;
99 	unsigned int rx_length;
100 	uint8_t *rx_buf;
101 
102 	unsigned int sync_id;
103 	unsigned int completed_id;
104 
105 	unsigned int int_enable;
106 };
107 
108 static void spi_engine_program_add_cmd(struct spi_engine_program *p,
109 	bool dry, uint16_t cmd)
110 {
111 	if (!dry)
112 		p->instructions[p->length] = cmd;
113 	p->length++;
114 }
115 
116 static unsigned int spi_engine_get_config(struct spi_device *spi)
117 {
118 	unsigned int config = 0;
119 
120 	if (spi->mode & SPI_CPOL)
121 		config |= SPI_ENGINE_CONFIG_CPOL;
122 	if (spi->mode & SPI_CPHA)
123 		config |= SPI_ENGINE_CONFIG_CPHA;
124 	if (spi->mode & SPI_3WIRE)
125 		config |= SPI_ENGINE_CONFIG_3WIRE;
126 
127 	return config;
128 }
129 
130 static unsigned int spi_engine_get_clk_div(struct spi_engine *spi_engine,
131 	struct spi_device *spi, struct spi_transfer *xfer)
132 {
133 	unsigned int clk_div;
134 
135 	clk_div = DIV_ROUND_UP(clk_get_rate(spi_engine->ref_clk),
136 		xfer->speed_hz * 2);
137 	if (clk_div > 255)
138 		clk_div = 255;
139 	else if (clk_div > 0)
140 		clk_div -= 1;
141 
142 	return clk_div;
143 }
144 
145 static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
146 	struct spi_transfer *xfer)
147 {
148 	unsigned int len = xfer->len;
149 
150 	while (len) {
151 		unsigned int n = min(len, 256U);
152 		unsigned int flags = 0;
153 
154 		if (xfer->tx_buf)
155 			flags |= SPI_ENGINE_TRANSFER_WRITE;
156 		if (xfer->rx_buf)
157 			flags |= SPI_ENGINE_TRANSFER_READ;
158 
159 		spi_engine_program_add_cmd(p, dry,
160 			SPI_ENGINE_CMD_TRANSFER(flags, n - 1));
161 		len -= n;
162 	}
163 }
164 
165 static void spi_engine_gen_sleep(struct spi_engine_program *p, bool dry,
166 	struct spi_engine *spi_engine, unsigned int clk_div,
167 	struct spi_transfer *xfer)
168 {
169 	unsigned int spi_clk = clk_get_rate(spi_engine->ref_clk);
170 	unsigned int t;
171 	int delay;
172 
173 	delay = spi_delay_to_ns(&xfer->delay, xfer);
174 	if (delay < 0)
175 		return;
176 	delay /= 1000;
177 
178 	if (delay == 0)
179 		return;
180 
181 	t = DIV_ROUND_UP(delay * spi_clk, (clk_div + 1) * 2);
182 	while (t) {
183 		unsigned int n = min(t, 256U);
184 
185 		spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_SLEEP(n - 1));
186 		t -= n;
187 	}
188 }
189 
190 static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
191 		struct spi_device *spi, bool assert)
192 {
193 	unsigned int mask = 0xff;
194 
195 	if (assert)
196 		mask ^= BIT(spi->chip_select);
197 
198 	spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_ASSERT(1, mask));
199 }
200 
201 static int spi_engine_compile_message(struct spi_engine *spi_engine,
202 	struct spi_message *msg, bool dry, struct spi_engine_program *p)
203 {
204 	struct spi_device *spi = msg->spi;
205 	struct spi_transfer *xfer;
206 	int clk_div, new_clk_div;
207 	bool cs_change = true;
208 
209 	clk_div = -1;
210 
211 	spi_engine_program_add_cmd(p, dry,
212 		SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CONFIG,
213 			spi_engine_get_config(spi)));
214 
215 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
216 		new_clk_div = spi_engine_get_clk_div(spi_engine, spi, xfer);
217 		if (new_clk_div != clk_div) {
218 			clk_div = new_clk_div;
219 			spi_engine_program_add_cmd(p, dry,
220 				SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CLK_DIV,
221 					clk_div));
222 		}
223 
224 		if (cs_change)
225 			spi_engine_gen_cs(p, dry, spi, true);
226 
227 		spi_engine_gen_xfer(p, dry, xfer);
228 		spi_engine_gen_sleep(p, dry, spi_engine, clk_div, xfer);
229 
230 		cs_change = xfer->cs_change;
231 		if (list_is_last(&xfer->transfer_list, &msg->transfers))
232 			cs_change = !cs_change;
233 
234 		if (cs_change)
235 			spi_engine_gen_cs(p, dry, spi, false);
236 	}
237 
238 	return 0;
239 }
240 
241 static void spi_engine_xfer_next(struct spi_engine *spi_engine,
242 	struct spi_transfer **_xfer)
243 {
244 	struct spi_message *msg = spi_engine->msg;
245 	struct spi_transfer *xfer = *_xfer;
246 
247 	if (!xfer) {
248 		xfer = list_first_entry(&msg->transfers,
249 			struct spi_transfer, transfer_list);
250 	} else if (list_is_last(&xfer->transfer_list, &msg->transfers)) {
251 		xfer = NULL;
252 	} else {
253 		xfer = list_next_entry(xfer, transfer_list);
254 	}
255 
256 	*_xfer = xfer;
257 }
258 
259 static void spi_engine_tx_next(struct spi_engine *spi_engine)
260 {
261 	struct spi_transfer *xfer = spi_engine->tx_xfer;
262 
263 	do {
264 		spi_engine_xfer_next(spi_engine, &xfer);
265 	} while (xfer && !xfer->tx_buf);
266 
267 	spi_engine->tx_xfer = xfer;
268 	if (xfer) {
269 		spi_engine->tx_length = xfer->len;
270 		spi_engine->tx_buf = xfer->tx_buf;
271 	} else {
272 		spi_engine->tx_buf = NULL;
273 	}
274 }
275 
276 static void spi_engine_rx_next(struct spi_engine *spi_engine)
277 {
278 	struct spi_transfer *xfer = spi_engine->rx_xfer;
279 
280 	do {
281 		spi_engine_xfer_next(spi_engine, &xfer);
282 	} while (xfer && !xfer->rx_buf);
283 
284 	spi_engine->rx_xfer = xfer;
285 	if (xfer) {
286 		spi_engine->rx_length = xfer->len;
287 		spi_engine->rx_buf = xfer->rx_buf;
288 	} else {
289 		spi_engine->rx_buf = NULL;
290 	}
291 }
292 
293 static bool spi_engine_write_cmd_fifo(struct spi_engine *spi_engine)
294 {
295 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_CMD_FIFO;
296 	unsigned int n, m, i;
297 	const uint16_t *buf;
298 
299 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_CMD_FIFO_ROOM);
300 	while (n && spi_engine->cmd_length) {
301 		m = min(n, spi_engine->cmd_length);
302 		buf = spi_engine->cmd_buf;
303 		for (i = 0; i < m; i++)
304 			writel_relaxed(buf[i], addr);
305 		spi_engine->cmd_buf += m;
306 		spi_engine->cmd_length -= m;
307 		n -= m;
308 	}
309 
310 	return spi_engine->cmd_length != 0;
311 }
312 
313 static bool spi_engine_write_tx_fifo(struct spi_engine *spi_engine)
314 {
315 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDO_DATA_FIFO;
316 	unsigned int n, m, i;
317 	const uint8_t *buf;
318 
319 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDO_FIFO_ROOM);
320 	while (n && spi_engine->tx_length) {
321 		m = min(n, spi_engine->tx_length);
322 		buf = spi_engine->tx_buf;
323 		for (i = 0; i < m; i++)
324 			writel_relaxed(buf[i], addr);
325 		spi_engine->tx_buf += m;
326 		spi_engine->tx_length -= m;
327 		n -= m;
328 		if (spi_engine->tx_length == 0)
329 			spi_engine_tx_next(spi_engine);
330 	}
331 
332 	return spi_engine->tx_length != 0;
333 }
334 
335 static bool spi_engine_read_rx_fifo(struct spi_engine *spi_engine)
336 {
337 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDI_DATA_FIFO;
338 	unsigned int n, m, i;
339 	uint8_t *buf;
340 
341 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDI_FIFO_LEVEL);
342 	while (n && spi_engine->rx_length) {
343 		m = min(n, spi_engine->rx_length);
344 		buf = spi_engine->rx_buf;
345 		for (i = 0; i < m; i++)
346 			buf[i] = readl_relaxed(addr);
347 		spi_engine->rx_buf += m;
348 		spi_engine->rx_length -= m;
349 		n -= m;
350 		if (spi_engine->rx_length == 0)
351 			spi_engine_rx_next(spi_engine);
352 	}
353 
354 	return spi_engine->rx_length != 0;
355 }
356 
357 static irqreturn_t spi_engine_irq(int irq, void *devid)
358 {
359 	struct spi_master *master = devid;
360 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
361 	unsigned int disable_int = 0;
362 	unsigned int pending;
363 
364 	pending = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
365 
366 	if (pending & SPI_ENGINE_INT_SYNC) {
367 		writel_relaxed(SPI_ENGINE_INT_SYNC,
368 			spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
369 		spi_engine->completed_id = readl_relaxed(
370 			spi_engine->base + SPI_ENGINE_REG_SYNC_ID);
371 	}
372 
373 	spin_lock(&spi_engine->lock);
374 
375 	if (pending & SPI_ENGINE_INT_CMD_ALMOST_EMPTY) {
376 		if (!spi_engine_write_cmd_fifo(spi_engine))
377 			disable_int |= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;
378 	}
379 
380 	if (pending & SPI_ENGINE_INT_SDO_ALMOST_EMPTY) {
381 		if (!spi_engine_write_tx_fifo(spi_engine))
382 			disable_int |= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;
383 	}
384 
385 	if (pending & (SPI_ENGINE_INT_SDI_ALMOST_FULL | SPI_ENGINE_INT_SYNC)) {
386 		if (!spi_engine_read_rx_fifo(spi_engine))
387 			disable_int |= SPI_ENGINE_INT_SDI_ALMOST_FULL;
388 	}
389 
390 	if (pending & SPI_ENGINE_INT_SYNC) {
391 		if (spi_engine->msg &&
392 		    spi_engine->completed_id == spi_engine->sync_id) {
393 			struct spi_message *msg = spi_engine->msg;
394 
395 			kfree(spi_engine->p);
396 			msg->status = 0;
397 			msg->actual_length = msg->frame_length;
398 			spi_engine->msg = NULL;
399 			spi_finalize_current_message(master);
400 			disable_int |= SPI_ENGINE_INT_SYNC;
401 		}
402 	}
403 
404 	if (disable_int) {
405 		spi_engine->int_enable &= ~disable_int;
406 		writel_relaxed(spi_engine->int_enable,
407 			spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
408 	}
409 
410 	spin_unlock(&spi_engine->lock);
411 
412 	return IRQ_HANDLED;
413 }
414 
415 static int spi_engine_transfer_one_message(struct spi_master *master,
416 	struct spi_message *msg)
417 {
418 	struct spi_engine_program p_dry, *p;
419 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
420 	unsigned int int_enable = 0;
421 	unsigned long flags;
422 	size_t size;
423 
424 	p_dry.length = 0;
425 	spi_engine_compile_message(spi_engine, msg, true, &p_dry);
426 
427 	size = sizeof(*p->instructions) * (p_dry.length + 1);
428 	p = kzalloc(sizeof(*p) + size, GFP_KERNEL);
429 	if (!p)
430 		return -ENOMEM;
431 	spi_engine_compile_message(spi_engine, msg, false, p);
432 
433 	spin_lock_irqsave(&spi_engine->lock, flags);
434 	spi_engine->sync_id = (spi_engine->sync_id + 1) & 0xff;
435 	spi_engine_program_add_cmd(p, false,
436 		SPI_ENGINE_CMD_SYNC(spi_engine->sync_id));
437 
438 	spi_engine->msg = msg;
439 	spi_engine->p = p;
440 
441 	spi_engine->cmd_buf = p->instructions;
442 	spi_engine->cmd_length = p->length;
443 	if (spi_engine_write_cmd_fifo(spi_engine))
444 		int_enable |= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;
445 
446 	spi_engine_tx_next(spi_engine);
447 	if (spi_engine_write_tx_fifo(spi_engine))
448 		int_enable |= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;
449 
450 	spi_engine_rx_next(spi_engine);
451 	if (spi_engine->rx_length != 0)
452 		int_enable |= SPI_ENGINE_INT_SDI_ALMOST_FULL;
453 
454 	int_enable |= SPI_ENGINE_INT_SYNC;
455 
456 	writel_relaxed(int_enable,
457 		spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
458 	spi_engine->int_enable = int_enable;
459 	spin_unlock_irqrestore(&spi_engine->lock, flags);
460 
461 	return 0;
462 }
463 
464 static int spi_engine_probe(struct platform_device *pdev)
465 {
466 	struct spi_engine *spi_engine;
467 	struct spi_master *master;
468 	unsigned int version;
469 	int irq;
470 	int ret;
471 
472 	irq = platform_get_irq(pdev, 0);
473 	if (irq <= 0)
474 		return -ENXIO;
475 
476 	spi_engine = devm_kzalloc(&pdev->dev, sizeof(*spi_engine), GFP_KERNEL);
477 	if (!spi_engine)
478 		return -ENOMEM;
479 
480 	master = spi_alloc_master(&pdev->dev, 0);
481 	if (!master)
482 		return -ENOMEM;
483 
484 	spi_master_set_devdata(master, spi_engine);
485 
486 	spin_lock_init(&spi_engine->lock);
487 
488 	spi_engine->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
489 	if (IS_ERR(spi_engine->clk)) {
490 		ret = PTR_ERR(spi_engine->clk);
491 		goto err_put_master;
492 	}
493 
494 	spi_engine->ref_clk = devm_clk_get(&pdev->dev, "spi_clk");
495 	if (IS_ERR(spi_engine->ref_clk)) {
496 		ret = PTR_ERR(spi_engine->ref_clk);
497 		goto err_put_master;
498 	}
499 
500 	ret = clk_prepare_enable(spi_engine->clk);
501 	if (ret)
502 		goto err_put_master;
503 
504 	ret = clk_prepare_enable(spi_engine->ref_clk);
505 	if (ret)
506 		goto err_clk_disable;
507 
508 	spi_engine->base = devm_platform_ioremap_resource(pdev, 0);
509 	if (IS_ERR(spi_engine->base)) {
510 		ret = PTR_ERR(spi_engine->base);
511 		goto err_ref_clk_disable;
512 	}
513 
514 	version = readl(spi_engine->base + SPI_ENGINE_REG_VERSION);
515 	if (SPI_ENGINE_VERSION_MAJOR(version) != 1) {
516 		dev_err(&pdev->dev, "Unsupported peripheral version %u.%u.%c\n",
517 			SPI_ENGINE_VERSION_MAJOR(version),
518 			SPI_ENGINE_VERSION_MINOR(version),
519 			SPI_ENGINE_VERSION_PATCH(version));
520 		ret = -ENODEV;
521 		goto err_ref_clk_disable;
522 	}
523 
524 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_RESET);
525 	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
526 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
527 
528 	ret = request_irq(irq, spi_engine_irq, 0, pdev->name, master);
529 	if (ret)
530 		goto err_ref_clk_disable;
531 
532 	master->dev.of_node = pdev->dev.of_node;
533 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_3WIRE;
534 	master->bits_per_word_mask = SPI_BPW_MASK(8);
535 	master->max_speed_hz = clk_get_rate(spi_engine->ref_clk) / 2;
536 	master->transfer_one_message = spi_engine_transfer_one_message;
537 	master->num_chipselect = 8;
538 
539 	ret = spi_register_master(master);
540 	if (ret)
541 		goto err_free_irq;
542 
543 	platform_set_drvdata(pdev, master);
544 
545 	return 0;
546 err_free_irq:
547 	free_irq(irq, master);
548 err_ref_clk_disable:
549 	clk_disable_unprepare(spi_engine->ref_clk);
550 err_clk_disable:
551 	clk_disable_unprepare(spi_engine->clk);
552 err_put_master:
553 	spi_master_put(master);
554 	return ret;
555 }
556 
557 static int spi_engine_remove(struct platform_device *pdev)
558 {
559 	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
560 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
561 	int irq = platform_get_irq(pdev, 0);
562 
563 	spi_unregister_master(master);
564 
565 	free_irq(irq, master);
566 
567 	spi_master_put(master);
568 
569 	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
570 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
571 	writel_relaxed(0x01, spi_engine->base + SPI_ENGINE_REG_RESET);
572 
573 	clk_disable_unprepare(spi_engine->ref_clk);
574 	clk_disable_unprepare(spi_engine->clk);
575 
576 	return 0;
577 }
578 
579 static const struct of_device_id spi_engine_match_table[] = {
580 	{ .compatible = "adi,axi-spi-engine-1.00.a" },
581 	{ },
582 };
583 MODULE_DEVICE_TABLE(of, spi_engine_match_table);
584 
585 static struct platform_driver spi_engine_driver = {
586 	.probe = spi_engine_probe,
587 	.remove = spi_engine_remove,
588 	.driver = {
589 		.name = "spi-engine",
590 		.of_match_table = spi_engine_match_table,
591 	},
592 };
593 module_platform_driver(spi_engine_driver);
594 
595 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
596 MODULE_DESCRIPTION("Analog Devices SPI engine peripheral driver");
597 MODULE_LICENSE("GPL");
598