xref: /openbmc/linux/drivers/spi/spi-bcm2835aux.c (revision d87c25e8)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Driver for Broadcom BCM2835 auxiliary SPI Controllers
4  *
5  * the driver does not rely on the native chipselects at all
6  * but only uses the gpio type chipselects
7  *
8  * Based on: spi-bcm2835.c
9  *
10  * Copyright (C) 2015 Martin Sperl
11  */
12 
13 #include <linux/clk.h>
14 #include <linux/completion.h>
15 #include <linux/debugfs.h>
16 #include <linux/delay.h>
17 #include <linux/err.h>
18 #include <linux/interrupt.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/of.h>
23 #include <linux/of_address.h>
24 #include <linux/of_device.h>
25 #include <linux/of_gpio.h>
26 #include <linux/of_irq.h>
27 #include <linux/regmap.h>
28 #include <linux/spi/spi.h>
29 #include <linux/spinlock.h>
30 
31 /* define polling limits */
32 static unsigned int polling_limit_us = 30;
33 module_param(polling_limit_us, uint, 0664);
34 MODULE_PARM_DESC(polling_limit_us,
35 		 "time in us to run a transfer in polling mode - if zero no polling is used\n");
36 
37 /*
38  * spi register defines
39  *
40  * note there is garbage in the "official" documentation,
41  * so some data is taken from the file:
42  *   brcm_usrlib/dag/vmcsx/vcinclude/bcm2708_chip/aux_io.h
43  * inside of:
44  *   http://www.broadcom.com/docs/support/videocore/Brcm_Android_ICS_Graphics_Stack.tar.gz
45  */
46 
47 /* SPI register offsets */
48 #define BCM2835_AUX_SPI_CNTL0	0x00
49 #define BCM2835_AUX_SPI_CNTL1	0x04
50 #define BCM2835_AUX_SPI_STAT	0x08
51 #define BCM2835_AUX_SPI_PEEK	0x0C
52 #define BCM2835_AUX_SPI_IO	0x20
53 #define BCM2835_AUX_SPI_TXHOLD	0x30
54 
55 /* Bitfields in CNTL0 */
56 #define BCM2835_AUX_SPI_CNTL0_SPEED	0xFFF00000
57 #define BCM2835_AUX_SPI_CNTL0_SPEED_MAX	0xFFF
58 #define BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT	20
59 #define BCM2835_AUX_SPI_CNTL0_CS	0x000E0000
60 #define BCM2835_AUX_SPI_CNTL0_POSTINPUT	0x00010000
61 #define BCM2835_AUX_SPI_CNTL0_VAR_CS	0x00008000
62 #define BCM2835_AUX_SPI_CNTL0_VAR_WIDTH	0x00004000
63 #define BCM2835_AUX_SPI_CNTL0_DOUTHOLD	0x00003000
64 #define BCM2835_AUX_SPI_CNTL0_ENABLE	0x00000800
65 #define BCM2835_AUX_SPI_CNTL0_IN_RISING	0x00000400
66 #define BCM2835_AUX_SPI_CNTL0_CLEARFIFO	0x00000200
67 #define BCM2835_AUX_SPI_CNTL0_OUT_RISING	0x00000100
68 #define BCM2835_AUX_SPI_CNTL0_CPOL	0x00000080
69 #define BCM2835_AUX_SPI_CNTL0_MSBF_OUT	0x00000040
70 #define BCM2835_AUX_SPI_CNTL0_SHIFTLEN	0x0000003F
71 
72 /* Bitfields in CNTL1 */
73 #define BCM2835_AUX_SPI_CNTL1_CSHIGH	0x00000700
74 #define BCM2835_AUX_SPI_CNTL1_TXEMPTY	0x00000080
75 #define BCM2835_AUX_SPI_CNTL1_IDLE	0x00000040
76 #define BCM2835_AUX_SPI_CNTL1_MSBF_IN	0x00000002
77 #define BCM2835_AUX_SPI_CNTL1_KEEP_IN	0x00000001
78 
79 /* Bitfields in STAT */
80 #define BCM2835_AUX_SPI_STAT_TX_LVL	0xFF000000
81 #define BCM2835_AUX_SPI_STAT_RX_LVL	0x00FF0000
82 #define BCM2835_AUX_SPI_STAT_TX_FULL	0x00000400
83 #define BCM2835_AUX_SPI_STAT_TX_EMPTY	0x00000200
84 #define BCM2835_AUX_SPI_STAT_RX_FULL	0x00000100
85 #define BCM2835_AUX_SPI_STAT_RX_EMPTY	0x00000080
86 #define BCM2835_AUX_SPI_STAT_BUSY	0x00000040
87 #define BCM2835_AUX_SPI_STAT_BITCOUNT	0x0000003F
88 
89 struct bcm2835aux_spi {
90 	void __iomem *regs;
91 	struct clk *clk;
92 	int irq;
93 	u32 cntl[2];
94 	const u8 *tx_buf;
95 	u8 *rx_buf;
96 	int tx_len;
97 	int rx_len;
98 	int pending;
99 
100 	u64 count_transfer_polling;
101 	u64 count_transfer_irq;
102 	u64 count_transfer_irq_after_poll;
103 
104 	struct dentry *debugfs_dir;
105 };
106 
107 #if defined(CONFIG_DEBUG_FS)
108 static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs,
109 				      const char *dname)
110 {
111 	char name[64];
112 	struct dentry *dir;
113 
114 	/* get full name */
115 	snprintf(name, sizeof(name), "spi-bcm2835aux-%s", dname);
116 
117 	/* the base directory */
118 	dir = debugfs_create_dir(name, NULL);
119 	bs->debugfs_dir = dir;
120 
121 	/* the counters */
122 	debugfs_create_u64("count_transfer_polling", 0444, dir,
123 			   &bs->count_transfer_polling);
124 	debugfs_create_u64("count_transfer_irq", 0444, dir,
125 			   &bs->count_transfer_irq);
126 	debugfs_create_u64("count_transfer_irq_after_poll", 0444, dir,
127 			   &bs->count_transfer_irq_after_poll);
128 }
129 
130 static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
131 {
132 	debugfs_remove_recursive(bs->debugfs_dir);
133 	bs->debugfs_dir = NULL;
134 }
135 #else
136 static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs,
137 				      const char *dname)
138 {
139 }
140 
141 static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
142 {
143 }
144 #endif /* CONFIG_DEBUG_FS */
145 
146 static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned int reg)
147 {
148 	return readl(bs->regs + reg);
149 }
150 
151 static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned int reg,
152 				 u32 val)
153 {
154 	writel(val, bs->regs + reg);
155 }
156 
157 static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs)
158 {
159 	u32 data;
160 	int count = min(bs->rx_len, 3);
161 
162 	data = bcm2835aux_rd(bs, BCM2835_AUX_SPI_IO);
163 	if (bs->rx_buf) {
164 		switch (count) {
165 		case 3:
166 			*bs->rx_buf++ = (data >> 16) & 0xff;
167 			fallthrough;
168 		case 2:
169 			*bs->rx_buf++ = (data >> 8) & 0xff;
170 			fallthrough;
171 		case 1:
172 			*bs->rx_buf++ = (data >> 0) & 0xff;
173 			/* fallthrough - no default */
174 		}
175 	}
176 	bs->rx_len -= count;
177 	bs->pending -= count;
178 }
179 
180 static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs)
181 {
182 	u32 data;
183 	u8 byte;
184 	int count;
185 	int i;
186 
187 	/* gather up to 3 bytes to write to the FIFO */
188 	count = min(bs->tx_len, 3);
189 	data = 0;
190 	for (i = 0; i < count; i++) {
191 		byte = bs->tx_buf ? *bs->tx_buf++ : 0;
192 		data |= byte << (8 * (2 - i));
193 	}
194 
195 	/* and set the variable bit-length */
196 	data |= (count * 8) << 24;
197 
198 	/* and decrement length */
199 	bs->tx_len -= count;
200 	bs->pending += count;
201 
202 	/* write to the correct TX-register */
203 	if (bs->tx_len)
204 		bcm2835aux_wr(bs, BCM2835_AUX_SPI_TXHOLD, data);
205 	else
206 		bcm2835aux_wr(bs, BCM2835_AUX_SPI_IO, data);
207 }
208 
209 static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
210 {
211 	/* disable spi clearing fifo and interrupts */
212 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, 0);
213 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0,
214 		      BCM2835_AUX_SPI_CNTL0_CLEARFIFO);
215 }
216 
217 static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs)
218 {
219 	u32 stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
220 
221 	/* check if we have data to read */
222 	for (; bs->rx_len && (stat & BCM2835_AUX_SPI_STAT_RX_LVL);
223 	     stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT))
224 		bcm2835aux_rd_fifo(bs);
225 
226 	/* check if we have data to write */
227 	while (bs->tx_len &&
228 	       (bs->pending < 12) &&
229 	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
230 		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
231 		bcm2835aux_wr_fifo(bs);
232 	}
233 }
234 
235 static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
236 {
237 	struct spi_master *master = dev_id;
238 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
239 
240 	/* IRQ may be shared, so return if our interrupts are disabled */
241 	if (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_CNTL1) &
242 	      (BCM2835_AUX_SPI_CNTL1_TXEMPTY | BCM2835_AUX_SPI_CNTL1_IDLE)))
243 		return IRQ_NONE;
244 
245 	/* do common fifo handling */
246 	bcm2835aux_spi_transfer_helper(bs);
247 
248 	if (!bs->tx_len) {
249 		/* disable tx fifo empty interrupt */
250 		bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
251 			BCM2835_AUX_SPI_CNTL1_IDLE);
252 	}
253 
254 	/* and if rx_len is 0 then disable interrupts and wake up completion */
255 	if (!bs->rx_len) {
256 		bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
257 		spi_finalize_current_transfer(master);
258 	}
259 
260 	return IRQ_HANDLED;
261 }
262 
263 static int __bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
264 					     struct spi_device *spi,
265 					     struct spi_transfer *tfr)
266 {
267 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
268 
269 	/* enable interrupts */
270 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
271 		BCM2835_AUX_SPI_CNTL1_TXEMPTY |
272 		BCM2835_AUX_SPI_CNTL1_IDLE);
273 
274 	/* and wait for finish... */
275 	return 1;
276 }
277 
278 static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
279 					   struct spi_device *spi,
280 					   struct spi_transfer *tfr)
281 {
282 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
283 
284 	/* update statistics */
285 	bs->count_transfer_irq++;
286 
287 	/* fill in registers and fifos before enabling interrupts */
288 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
289 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
290 
291 	/* fill in tx fifo with data before enabling interrupts */
292 	while ((bs->tx_len) &&
293 	       (bs->pending < 12) &&
294 	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
295 		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
296 		bcm2835aux_wr_fifo(bs);
297 	}
298 
299 	/* now run the interrupt mode */
300 	return __bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
301 }
302 
303 static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
304 					    struct spi_device *spi,
305 					struct spi_transfer *tfr)
306 {
307 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
308 	unsigned long timeout;
309 
310 	/* update statistics */
311 	bs->count_transfer_polling++;
312 
313 	/* configure spi */
314 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
315 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
316 
317 	/* set the timeout to at least 2 jiffies */
318 	timeout = jiffies + 2 + HZ * polling_limit_us / 1000000;
319 
320 	/* loop until finished the transfer */
321 	while (bs->rx_len) {
322 
323 		/* do common fifo handling */
324 		bcm2835aux_spi_transfer_helper(bs);
325 
326 		/* there is still data pending to read check the timeout */
327 		if (bs->rx_len && time_after(jiffies, timeout)) {
328 			dev_dbg_ratelimited(&spi->dev,
329 					    "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
330 					    jiffies - timeout,
331 					    bs->tx_len, bs->rx_len);
332 			/* forward to interrupt handler */
333 			bs->count_transfer_irq_after_poll++;
334 			return __bcm2835aux_spi_transfer_one_irq(master,
335 							       spi, tfr);
336 		}
337 	}
338 
339 	/* and return without waiting for completion */
340 	return 0;
341 }
342 
343 static int bcm2835aux_spi_transfer_one(struct spi_master *master,
344 				       struct spi_device *spi,
345 				       struct spi_transfer *tfr)
346 {
347 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
348 	unsigned long spi_hz, clk_hz, speed;
349 	unsigned long hz_per_byte, byte_limit;
350 
351 	/* calculate the registers to handle
352 	 *
353 	 * note that we use the variable data mode, which
354 	 * is not optimal for longer transfers as we waste registers
355 	 * resulting (potentially) in more interrupts when transferring
356 	 * more than 12 bytes
357 	 */
358 
359 	/* set clock */
360 	spi_hz = tfr->speed_hz;
361 	clk_hz = clk_get_rate(bs->clk);
362 
363 	if (spi_hz >= clk_hz / 2) {
364 		speed = 0;
365 	} else if (spi_hz) {
366 		speed = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
367 		if (speed >  BCM2835_AUX_SPI_CNTL0_SPEED_MAX)
368 			speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
369 	} else { /* the slowest we can go */
370 		speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
371 	}
372 	/* mask out old speed from previous spi_transfer */
373 	bs->cntl[0] &= ~(BCM2835_AUX_SPI_CNTL0_SPEED);
374 	/* set the new speed */
375 	bs->cntl[0] |= speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT;
376 
377 	tfr->effective_speed_hz = clk_hz / (2 * (speed + 1));
378 
379 	/* set transmit buffers and length */
380 	bs->tx_buf = tfr->tx_buf;
381 	bs->rx_buf = tfr->rx_buf;
382 	bs->tx_len = tfr->len;
383 	bs->rx_len = tfr->len;
384 	bs->pending = 0;
385 
386 	/* Calculate the estimated time in us the transfer runs.  Note that
387 	 * there are 2 idle clocks cycles after each chunk getting
388 	 * transferred - in our case the chunk size is 3 bytes, so we
389 	 * approximate this by 9 cycles/byte.  This is used to find the number
390 	 * of Hz per byte per polling limit.  E.g., we can transfer 1 byte in
391 	 * 30 µs per 300,000 Hz of bus clock.
392 	 */
393 	hz_per_byte = polling_limit_us ? (9 * 1000000) / polling_limit_us : 0;
394 	byte_limit = hz_per_byte ? tfr->effective_speed_hz / hz_per_byte : 1;
395 
396 	/* run in polling mode for short transfers */
397 	if (tfr->len < byte_limit)
398 		return bcm2835aux_spi_transfer_one_poll(master, spi, tfr);
399 
400 	/* run in interrupt mode for all others */
401 	return bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
402 }
403 
404 static int bcm2835aux_spi_prepare_message(struct spi_master *master,
405 					  struct spi_message *msg)
406 {
407 	struct spi_device *spi = msg->spi;
408 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
409 
410 	bs->cntl[0] = BCM2835_AUX_SPI_CNTL0_ENABLE |
411 		      BCM2835_AUX_SPI_CNTL0_VAR_WIDTH |
412 		      BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
413 	bs->cntl[1] = BCM2835_AUX_SPI_CNTL1_MSBF_IN;
414 
415 	/* handle all the modes */
416 	if (spi->mode & SPI_CPOL) {
417 		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPOL;
418 		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_OUT_RISING;
419 	} else {
420 		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_IN_RISING;
421 	}
422 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
423 	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
424 
425 	return 0;
426 }
427 
428 static int bcm2835aux_spi_unprepare_message(struct spi_master *master,
429 					    struct spi_message *msg)
430 {
431 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
432 
433 	bcm2835aux_spi_reset_hw(bs);
434 
435 	return 0;
436 }
437 
438 static void bcm2835aux_spi_handle_err(struct spi_master *master,
439 				      struct spi_message *msg)
440 {
441 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
442 
443 	bcm2835aux_spi_reset_hw(bs);
444 }
445 
446 static int bcm2835aux_spi_setup(struct spi_device *spi)
447 {
448 	int ret;
449 
450 	/* sanity check for native cs */
451 	if (spi->mode & SPI_NO_CS)
452 		return 0;
453 	if (gpio_is_valid(spi->cs_gpio)) {
454 		/* with gpio-cs set the GPIO to the correct level
455 		 * and as output (in case the dt has the gpio not configured
456 		 * as output but native cs)
457 		 */
458 		ret = gpio_direction_output(spi->cs_gpio,
459 					    (spi->mode & SPI_CS_HIGH) ? 0 : 1);
460 		if (ret)
461 			dev_err(&spi->dev,
462 				"could not set gpio %i as output: %i\n",
463 				spi->cs_gpio, ret);
464 
465 		return ret;
466 	}
467 
468 	/* for dt-backwards compatibility: only support native on CS0
469 	 * known things not supported with broken native CS:
470 	 * * multiple chip-selects: cs0-cs2 are all
471 	 *     simultaniously asserted whenever there is a transfer
472 	 *     this even includes SPI_NO_CS
473 	 * * SPI_CS_HIGH: cs are always asserted low
474 	 * * cs_change: cs is deasserted after each spi_transfer
475 	 * * cs_delay_usec: cs is always deasserted one SCK cycle
476 	 *     after the last transfer
477 	 * probably more...
478 	 */
479 	dev_warn(&spi->dev,
480 		 "Native CS is not supported - please configure cs-gpio in device-tree\n");
481 
482 	if (spi->chip_select == 0)
483 		return 0;
484 
485 	dev_warn(&spi->dev, "Native CS is not working for cs > 0\n");
486 
487 	return -EINVAL;
488 }
489 
490 static int bcm2835aux_spi_probe(struct platform_device *pdev)
491 {
492 	struct spi_master *master;
493 	struct bcm2835aux_spi *bs;
494 	unsigned long clk_hz;
495 	int err;
496 
497 	master = devm_spi_alloc_master(&pdev->dev, sizeof(*bs));
498 	if (!master)
499 		return -ENOMEM;
500 
501 	platform_set_drvdata(pdev, master);
502 	master->mode_bits = (SPI_CPOL | SPI_CS_HIGH | SPI_NO_CS);
503 	master->bits_per_word_mask = SPI_BPW_MASK(8);
504 	/* even though the driver never officially supported native CS
505 	 * allow a single native CS for legacy DT support purposes when
506 	 * no cs-gpio is configured.
507 	 * Known limitations for native cs are:
508 	 * * multiple chip-selects: cs0-cs2 are all simultaniously asserted
509 	 *     whenever there is a transfer -  this even includes SPI_NO_CS
510 	 * * SPI_CS_HIGH: is ignores - cs are always asserted low
511 	 * * cs_change: cs is deasserted after each spi_transfer
512 	 * * cs_delay_usec: cs is always deasserted one SCK cycle after
513 	 *     a spi_transfer
514 	 */
515 	master->num_chipselect = 1;
516 	master->setup = bcm2835aux_spi_setup;
517 	master->transfer_one = bcm2835aux_spi_transfer_one;
518 	master->handle_err = bcm2835aux_spi_handle_err;
519 	master->prepare_message = bcm2835aux_spi_prepare_message;
520 	master->unprepare_message = bcm2835aux_spi_unprepare_message;
521 	master->dev.of_node = pdev->dev.of_node;
522 
523 	bs = spi_master_get_devdata(master);
524 
525 	/* the main area */
526 	bs->regs = devm_platform_ioremap_resource(pdev, 0);
527 	if (IS_ERR(bs->regs))
528 		return PTR_ERR(bs->regs);
529 
530 	bs->clk = devm_clk_get(&pdev->dev, NULL);
531 	if (IS_ERR(bs->clk)) {
532 		err = PTR_ERR(bs->clk);
533 		dev_err(&pdev->dev, "could not get clk: %d\n", err);
534 		return err;
535 	}
536 
537 	bs->irq = platform_get_irq(pdev, 0);
538 	if (bs->irq <= 0)
539 		return bs->irq ? bs->irq : -ENODEV;
540 
541 	/* this also enables the HW block */
542 	err = clk_prepare_enable(bs->clk);
543 	if (err) {
544 		dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
545 		return err;
546 	}
547 
548 	/* just checking if the clock returns a sane value */
549 	clk_hz = clk_get_rate(bs->clk);
550 	if (!clk_hz) {
551 		dev_err(&pdev->dev, "clock returns 0 Hz\n");
552 		err = -ENODEV;
553 		goto out_clk_disable;
554 	}
555 
556 	/* reset SPI-HW block */
557 	bcm2835aux_spi_reset_hw(bs);
558 
559 	err = devm_request_irq(&pdev->dev, bs->irq,
560 			       bcm2835aux_spi_interrupt,
561 			       IRQF_SHARED,
562 			       dev_name(&pdev->dev), master);
563 	if (err) {
564 		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
565 		goto out_clk_disable;
566 	}
567 
568 	err = spi_register_master(master);
569 	if (err) {
570 		dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
571 		goto out_clk_disable;
572 	}
573 
574 	bcm2835aux_debugfs_create(bs, dev_name(&pdev->dev));
575 
576 	return 0;
577 
578 out_clk_disable:
579 	clk_disable_unprepare(bs->clk);
580 	return err;
581 }
582 
583 static int bcm2835aux_spi_remove(struct platform_device *pdev)
584 {
585 	struct spi_master *master = platform_get_drvdata(pdev);
586 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
587 
588 	bcm2835aux_debugfs_remove(bs);
589 
590 	spi_unregister_master(master);
591 
592 	bcm2835aux_spi_reset_hw(bs);
593 
594 	/* disable the HW block by releasing the clock */
595 	clk_disable_unprepare(bs->clk);
596 
597 	return 0;
598 }
599 
600 static const struct of_device_id bcm2835aux_spi_match[] = {
601 	{ .compatible = "brcm,bcm2835-aux-spi", },
602 	{}
603 };
604 MODULE_DEVICE_TABLE(of, bcm2835aux_spi_match);
605 
606 static struct platform_driver bcm2835aux_spi_driver = {
607 	.driver		= {
608 		.name		= "spi-bcm2835aux",
609 		.of_match_table	= bcm2835aux_spi_match,
610 	},
611 	.probe		= bcm2835aux_spi_probe,
612 	.remove		= bcm2835aux_spi_remove,
613 };
614 module_platform_driver(bcm2835aux_spi_driver);
615 
616 MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835 aux");
617 MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
618 MODULE_LICENSE("GPL");
619