gpio: rcar: Fix runtime PM imbalance on error
[linux/fpc-iii.git] / drivers / spi / spi-bcm2835aux.c
bloba2162ff56a121f1a5072d9c87251c8986cb80521
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Driver for Broadcom BCM2835 auxiliary SPI Controllers
5 * the driver does not rely on the native chipselects at all
6 * but only uses the gpio type chipselects
8 * Based on: spi-bcm2835.c
10 * Copyright (C) 2015 Martin Sperl
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>
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");
38 * spi register defines
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
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
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
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
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
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;
100 u64 count_transfer_polling;
101 u64 count_transfer_irq;
102 u64 count_transfer_irq_after_poll;
104 struct dentry *debugfs_dir;
107 #if defined(CONFIG_DEBUG_FS)
108 static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs,
109 const char *dname)
111 char name[64];
112 struct dentry *dir;
114 /* get full name */
115 snprintf(name, sizeof(name), "spi-bcm2835aux-%s", dname);
117 /* the base directory */
118 dir = debugfs_create_dir(name, NULL);
119 bs->debugfs_dir = dir;
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);
130 static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
132 debugfs_remove_recursive(bs->debugfs_dir);
133 bs->debugfs_dir = NULL;
135 #else
136 static void bcm2835aux_debugfs_create(struct bcm2835aux_spi *bs,
137 const char *dname)
141 static void bcm2835aux_debugfs_remove(struct bcm2835aux_spi *bs)
144 #endif /* CONFIG_DEBUG_FS */
146 static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg)
148 return readl(bs->regs + reg);
151 static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned reg,
152 u32 val)
154 writel(val, bs->regs + reg);
157 static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs)
159 u32 data;
160 int count = min(bs->rx_len, 3);
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 */
176 bs->rx_len -= count;
177 bs->pending -= count;
180 static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs)
182 u32 data;
183 u8 byte;
184 int count;
185 int i;
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));
195 /* and set the variable bit-length */
196 data |= (count * 8) << 24;
198 /* and decrement length */
199 bs->tx_len -= count;
200 bs->pending += count;
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);
209 static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
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);
217 static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs)
219 u32 stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
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);
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);
235 static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
237 struct spi_master *master = dev_id;
238 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
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;
245 /* do common fifo handling */
246 bcm2835aux_spi_transfer_helper(bs);
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);
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 complete(&master->xfer_completion);
260 return IRQ_HANDLED;
263 static int __bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
264 struct spi_device *spi,
265 struct spi_transfer *tfr)
267 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
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);
274 /* and wait for finish... */
275 return 1;
278 static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
279 struct spi_device *spi,
280 struct spi_transfer *tfr)
282 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
284 /* update statistics */
285 bs->count_transfer_irq++;
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]);
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);
299 /* now run the interrupt mode */
300 return __bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
303 static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
304 struct spi_device *spi,
305 struct spi_transfer *tfr)
307 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
308 unsigned long timeout;
310 /* update statistics */
311 bs->count_transfer_polling++;
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]);
317 /* set the timeout to at least 2 jiffies */
318 timeout = jiffies + 2 + HZ * polling_limit_us / 1000000;
320 /* loop until finished the transfer */
321 while (bs->rx_len) {
323 /* do common fifo handling */
324 bcm2835aux_spi_transfer_helper(bs);
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);
339 /* and return without waiting for completion */
340 return 0;
343 static int bcm2835aux_spi_transfer_one(struct spi_master *master,
344 struct spi_device *spi,
345 struct spi_transfer *tfr)
347 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
348 unsigned long spi_hz, clk_hz, speed, spi_used_hz;
349 unsigned long hz_per_byte, byte_limit;
351 /* calculate the registers to handle
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
359 /* set clock */
360 spi_hz = tfr->speed_hz;
361 clk_hz = clk_get_rate(bs->clk);
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;
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;
377 spi_used_hz = clk_hz / (2 * (speed + 1));
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;
386 /* Calculate the estimated time in us the transfer runs. Note that
387 * there are 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.
393 hz_per_byte = polling_limit_us ? (9 * 1000000) / polling_limit_us : 0;
394 byte_limit = hz_per_byte ? spi_used_hz / hz_per_byte : 1;
396 /* run in polling mode for short transfers */
397 if (tfr->len < byte_limit)
398 return bcm2835aux_spi_transfer_one_poll(master, spi, tfr);
400 /* run in interrupt mode for all others */
401 return bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
404 static int bcm2835aux_spi_prepare_message(struct spi_master *master,
405 struct spi_message *msg)
407 struct spi_device *spi = msg->spi;
408 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
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;
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;
422 bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
423 bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
425 return 0;
428 static int bcm2835aux_spi_unprepare_message(struct spi_master *master,
429 struct spi_message *msg)
431 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
433 bcm2835aux_spi_reset_hw(bs);
435 return 0;
438 static void bcm2835aux_spi_handle_err(struct spi_master *master,
439 struct spi_message *msg)
441 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
443 bcm2835aux_spi_reset_hw(bs);
446 static int bcm2835aux_spi_setup(struct spi_device *spi)
448 int ret;
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)
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);
465 return ret;
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...
479 dev_warn(&spi->dev,
480 "Native CS is not supported - please configure cs-gpio in device-tree\n");
482 if (spi->chip_select == 0)
483 return 0;
485 dev_warn(&spi->dev, "Native CS is not working for cs > 0\n");
487 return -EINVAL;
490 static int bcm2835aux_spi_probe(struct platform_device *pdev)
492 struct spi_master *master;
493 struct bcm2835aux_spi *bs;
494 unsigned long clk_hz;
495 int err;
497 master = spi_alloc_master(&pdev->dev, sizeof(*bs));
498 if (!master)
499 return -ENOMEM;
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
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;
523 bs = spi_master_get_devdata(master);
525 /* the main area */
526 bs->regs = devm_platform_ioremap_resource(pdev, 0);
527 if (IS_ERR(bs->regs)) {
528 err = PTR_ERR(bs->regs);
529 goto out_master_put;
532 bs->clk = devm_clk_get(&pdev->dev, NULL);
533 if (IS_ERR(bs->clk)) {
534 err = PTR_ERR(bs->clk);
535 dev_err(&pdev->dev, "could not get clk: %d\n", err);
536 goto out_master_put;
539 bs->irq = platform_get_irq(pdev, 0);
540 if (bs->irq <= 0) {
541 err = bs->irq ? bs->irq : -ENODEV;
542 goto out_master_put;
545 /* this also enables the HW block */
546 err = clk_prepare_enable(bs->clk);
547 if (err) {
548 dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
549 goto out_master_put;
552 /* just checking if the clock returns a sane value */
553 clk_hz = clk_get_rate(bs->clk);
554 if (!clk_hz) {
555 dev_err(&pdev->dev, "clock returns 0 Hz\n");
556 err = -ENODEV;
557 goto out_clk_disable;
560 /* reset SPI-HW block */
561 bcm2835aux_spi_reset_hw(bs);
563 err = devm_request_irq(&pdev->dev, bs->irq,
564 bcm2835aux_spi_interrupt,
565 IRQF_SHARED,
566 dev_name(&pdev->dev), master);
567 if (err) {
568 dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
569 goto out_clk_disable;
572 err = devm_spi_register_master(&pdev->dev, master);
573 if (err) {
574 dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
575 goto out_clk_disable;
578 bcm2835aux_debugfs_create(bs, dev_name(&pdev->dev));
580 return 0;
582 out_clk_disable:
583 clk_disable_unprepare(bs->clk);
584 out_master_put:
585 spi_master_put(master);
586 return err;
589 static int bcm2835aux_spi_remove(struct platform_device *pdev)
591 struct spi_master *master = platform_get_drvdata(pdev);
592 struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
594 bcm2835aux_debugfs_remove(bs);
596 bcm2835aux_spi_reset_hw(bs);
598 /* disable the HW block by releasing the clock */
599 clk_disable_unprepare(bs->clk);
601 return 0;
604 static const struct of_device_id bcm2835aux_spi_match[] = {
605 { .compatible = "brcm,bcm2835-aux-spi", },
608 MODULE_DEVICE_TABLE(of, bcm2835aux_spi_match);
610 static struct platform_driver bcm2835aux_spi_driver = {
611 .driver = {
612 .name = "spi-bcm2835aux",
613 .of_match_table = bcm2835aux_spi_match,
615 .probe = bcm2835aux_spi_probe,
616 .remove = bcm2835aux_spi_remove,
618 module_platform_driver(bcm2835aux_spi_driver);
620 MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835 aux");
621 MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
622 MODULE_LICENSE("GPL");