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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for Cirrus Logic EP93xx SPI controller.
4 *
5 * Copyright (C) 2010-2011 Mika Westerberg
6 *
7 * Explicit FIFO handling code was inspired by amba-pl022 driver.
8 *
9 * Chip select support using other than built-in GPIOs by H. Hartley Sweeten.
10 *
11 * For more information about the SPI controller see documentation on Cirrus
12 * Logic web site:
13 * https://www.cirrus.com/en/pubs/manual/EP93xx_Users_Guide_UM1.pdf
14 */
15
16#include <linux/io.h>
17#include <linux/clk.h>
18#include <linux/err.h>
19#include <linux/delay.h>
20#include <linux/device.h>
21#include <linux/dmaengine.h>
22#include <linux/bitops.h>
23#include <linux/interrupt.h>
24#include <linux/module.h>
25#include <linux/platform_device.h>
26#include <linux/sched.h>
27#include <linux/scatterlist.h>
28#include <linux/spi/spi.h>
29
30#include <linux/platform_data/dma-ep93xx.h>
31#include <linux/platform_data/spi-ep93xx.h>
32
33#define SSPCR0 0x0000
34#define SSPCR0_SPO BIT(6)
35#define SSPCR0_SPH BIT(7)
36#define SSPCR0_SCR_SHIFT 8
37
38#define SSPCR1 0x0004
39#define SSPCR1_RIE BIT(0)
40#define SSPCR1_TIE BIT(1)
41#define SSPCR1_RORIE BIT(2)
42#define SSPCR1_LBM BIT(3)
43#define SSPCR1_SSE BIT(4)
44#define SSPCR1_MS BIT(5)
45#define SSPCR1_SOD BIT(6)
46
47#define SSPDR 0x0008
48
49#define SSPSR 0x000c
50#define SSPSR_TFE BIT(0)
51#define SSPSR_TNF BIT(1)
52#define SSPSR_RNE BIT(2)
53#define SSPSR_RFF BIT(3)
54#define SSPSR_BSY BIT(4)
55#define SSPCPSR 0x0010
56
57#define SSPIIR 0x0014
58#define SSPIIR_RIS BIT(0)
59#define SSPIIR_TIS BIT(1)
60#define SSPIIR_RORIS BIT(2)
61#define SSPICR SSPIIR
62
63/* timeout in milliseconds */
64#define SPI_TIMEOUT 5
65/* maximum depth of RX/TX FIFO */
66#define SPI_FIFO_SIZE 8
67
68/**
69 * struct ep93xx_spi - EP93xx SPI controller structure
70 * @clk: clock for the controller
71 * @mmio: pointer to ioremap()'d registers
72 * @sspdr_phys: physical address of the SSPDR register
73 * @tx: current byte in transfer to transmit
74 * @rx: current byte in transfer to receive
75 * @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one
76 * frame decreases this level and sending one frame increases it.
77 * @dma_rx: RX DMA channel
78 * @dma_tx: TX DMA channel
79 * @dma_rx_data: RX parameters passed to the DMA engine
80 * @dma_tx_data: TX parameters passed to the DMA engine
81 * @rx_sgt: sg table for RX transfers
82 * @tx_sgt: sg table for TX transfers
83 * @zeropage: dummy page used as RX buffer when only TX buffer is passed in by
84 * the client
85 */
86struct ep93xx_spi {
87 struct clk *clk;
88 void __iomem *mmio;
89 unsigned long sspdr_phys;
90 size_t tx;
91 size_t rx;
92 size_t fifo_level;
93 struct dma_chan *dma_rx;
94 struct dma_chan *dma_tx;
95 struct ep93xx_dma_data dma_rx_data;
96 struct ep93xx_dma_data dma_tx_data;
97 struct sg_table rx_sgt;
98 struct sg_table tx_sgt;
99 void *zeropage;
100};
101
102/* converts bits per word to CR0.DSS value */
103#define bits_per_word_to_dss(bpw) ((bpw) - 1)
104
105/**
106 * ep93xx_spi_calc_divisors() - calculates SPI clock divisors
107 * @host: SPI host
108 * @rate: desired SPI output clock rate
109 * @div_cpsr: pointer to return the cpsr (pre-scaler) divider
110 * @div_scr: pointer to return the scr divider
111 */
112static int ep93xx_spi_calc_divisors(struct spi_controller *host,
113 u32 rate, u8 *div_cpsr, u8 *div_scr)
114{
115 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
116 unsigned long spi_clk_rate = clk_get_rate(espi->clk);
117 int cpsr, scr;
118
119 /*
120 * Make sure that max value is between values supported by the
121 * controller.
122 */
123 rate = clamp(rate, host->min_speed_hz, host->max_speed_hz);
124
125 /*
126 * Calculate divisors so that we can get speed according the
127 * following formula:
128 * rate = spi_clock_rate / (cpsr * (1 + scr))
129 *
130 * cpsr must be even number and starts from 2, scr can be any number
131 * between 0 and 255.
132 */
133 for (cpsr = 2; cpsr <= 254; cpsr += 2) {
134 for (scr = 0; scr <= 255; scr++) {
135 if ((spi_clk_rate / (cpsr * (scr + 1))) <= rate) {
136 *div_scr = (u8)scr;
137 *div_cpsr = (u8)cpsr;
138 return 0;
139 }
140 }
141 }
142
143 return -EINVAL;
144}
145
146static int ep93xx_spi_chip_setup(struct spi_controller *host,
147 struct spi_device *spi,
148 struct spi_transfer *xfer)
149{
150 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
151 u8 dss = bits_per_word_to_dss(xfer->bits_per_word);
152 u8 div_cpsr = 0;
153 u8 div_scr = 0;
154 u16 cr0;
155 int err;
156
157 err = ep93xx_spi_calc_divisors(host, xfer->speed_hz,
158 &div_cpsr, &div_scr);
159 if (err)
160 return err;
161
162 cr0 = div_scr << SSPCR0_SCR_SHIFT;
163 if (spi->mode & SPI_CPOL)
164 cr0 |= SSPCR0_SPO;
165 if (spi->mode & SPI_CPHA)
166 cr0 |= SSPCR0_SPH;
167 cr0 |= dss;
168
169 dev_dbg(&host->dev, "setup: mode %d, cpsr %d, scr %d, dss %d\n",
170 spi->mode, div_cpsr, div_scr, dss);
171 dev_dbg(&host->dev, "setup: cr0 %#x\n", cr0);
172
173 writel(div_cpsr, espi->mmio + SSPCPSR);
174 writel(cr0, espi->mmio + SSPCR0);
175
176 return 0;
177}
178
179static void ep93xx_do_write(struct spi_controller *host)
180{
181 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
182 struct spi_transfer *xfer = host->cur_msg->state;
183 u32 val = 0;
184
185 if (xfer->bits_per_word > 8) {
186 if (xfer->tx_buf)
187 val = ((u16 *)xfer->tx_buf)[espi->tx];
188 espi->tx += 2;
189 } else {
190 if (xfer->tx_buf)
191 val = ((u8 *)xfer->tx_buf)[espi->tx];
192 espi->tx += 1;
193 }
194 writel(val, espi->mmio + SSPDR);
195}
196
197static void ep93xx_do_read(struct spi_controller *host)
198{
199 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
200 struct spi_transfer *xfer = host->cur_msg->state;
201 u32 val;
202
203 val = readl(espi->mmio + SSPDR);
204 if (xfer->bits_per_word > 8) {
205 if (xfer->rx_buf)
206 ((u16 *)xfer->rx_buf)[espi->rx] = val;
207 espi->rx += 2;
208 } else {
209 if (xfer->rx_buf)
210 ((u8 *)xfer->rx_buf)[espi->rx] = val;
211 espi->rx += 1;
212 }
213}
214
215/**
216 * ep93xx_spi_read_write() - perform next RX/TX transfer
217 * @host: SPI host
218 *
219 * This function transfers next bytes (or half-words) to/from RX/TX FIFOs. If
220 * called several times, the whole transfer will be completed. Returns
221 * %-EINPROGRESS when current transfer was not yet completed otherwise %0.
222 *
223 * When this function is finished, RX FIFO should be empty and TX FIFO should be
224 * full.
225 */
226static int ep93xx_spi_read_write(struct spi_controller *host)
227{
228 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
229 struct spi_transfer *xfer = host->cur_msg->state;
230
231 /* read as long as RX FIFO has frames in it */
232 while ((readl(espi->mmio + SSPSR) & SSPSR_RNE)) {
233 ep93xx_do_read(host);
234 espi->fifo_level--;
235 }
236
237 /* write as long as TX FIFO has room */
238 while (espi->fifo_level < SPI_FIFO_SIZE && espi->tx < xfer->len) {
239 ep93xx_do_write(host);
240 espi->fifo_level++;
241 }
242
243 if (espi->rx == xfer->len)
244 return 0;
245
246 return -EINPROGRESS;
247}
248
249static enum dma_transfer_direction
250ep93xx_dma_data_to_trans_dir(enum dma_data_direction dir)
251{
252 switch (dir) {
253 case DMA_TO_DEVICE:
254 return DMA_MEM_TO_DEV;
255 case DMA_FROM_DEVICE:
256 return DMA_DEV_TO_MEM;
257 default:
258 return DMA_TRANS_NONE;
259 }
260}
261
262/**
263 * ep93xx_spi_dma_prepare() - prepares a DMA transfer
264 * @host: SPI host
265 * @dir: DMA transfer direction
266 *
267 * Function configures the DMA, maps the buffer and prepares the DMA
268 * descriptor. Returns a valid DMA descriptor in case of success and ERR_PTR
269 * in case of failure.
270 */
271static struct dma_async_tx_descriptor *
272ep93xx_spi_dma_prepare(struct spi_controller *host,
273 enum dma_data_direction dir)
274{
275 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
276 struct spi_transfer *xfer = host->cur_msg->state;
277 struct dma_async_tx_descriptor *txd;
278 enum dma_slave_buswidth buswidth;
279 struct dma_slave_config conf;
280 struct scatterlist *sg;
281 struct sg_table *sgt;
282 struct dma_chan *chan;
283 const void *buf, *pbuf;
284 size_t len = xfer->len;
285 int i, ret, nents;
286
287 if (xfer->bits_per_word > 8)
288 buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
289 else
290 buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
291
292 memset(&conf, 0, sizeof(conf));
293 conf.direction = ep93xx_dma_data_to_trans_dir(dir);
294
295 if (dir == DMA_FROM_DEVICE) {
296 chan = espi->dma_rx;
297 buf = xfer->rx_buf;
298 sgt = &espi->rx_sgt;
299
300 conf.src_addr = espi->sspdr_phys;
301 conf.src_addr_width = buswidth;
302 } else {
303 chan = espi->dma_tx;
304 buf = xfer->tx_buf;
305 sgt = &espi->tx_sgt;
306
307 conf.dst_addr = espi->sspdr_phys;
308 conf.dst_addr_width = buswidth;
309 }
310
311 ret = dmaengine_slave_config(chan, &conf);
312 if (ret)
313 return ERR_PTR(ret);
314
315 /*
316 * We need to split the transfer into PAGE_SIZE'd chunks. This is
317 * because we are using @espi->zeropage to provide a zero RX buffer
318 * for the TX transfers and we have only allocated one page for that.
319 *
320 * For performance reasons we allocate a new sg_table only when
321 * needed. Otherwise we will re-use the current one. Eventually the
322 * last sg_table is released in ep93xx_spi_release_dma().
323 */
324
325 nents = DIV_ROUND_UP(len, PAGE_SIZE);
326 if (nents != sgt->nents) {
327 sg_free_table(sgt);
328
329 ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
330 if (ret)
331 return ERR_PTR(ret);
332 }
333
334 pbuf = buf;
335 for_each_sg(sgt->sgl, sg, sgt->nents, i) {
336 size_t bytes = min_t(size_t, len, PAGE_SIZE);
337
338 if (buf) {
339 sg_set_page(sg, virt_to_page(pbuf), bytes,
340 offset_in_page(pbuf));
341 } else {
342 sg_set_page(sg, virt_to_page(espi->zeropage),
343 bytes, 0);
344 }
345
346 pbuf += bytes;
347 len -= bytes;
348 }
349
350 if (WARN_ON(len)) {
351 dev_warn(&host->dev, "len = %zu expected 0!\n", len);
352 return ERR_PTR(-EINVAL);
353 }
354
355 nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
356 if (!nents)
357 return ERR_PTR(-ENOMEM);
358
359 txd = dmaengine_prep_slave_sg(chan, sgt->sgl, nents, conf.direction,
360 DMA_CTRL_ACK);
361 if (!txd) {
362 dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
363 return ERR_PTR(-ENOMEM);
364 }
365 return txd;
366}
367
368/**
369 * ep93xx_spi_dma_finish() - finishes with a DMA transfer
370 * @host: SPI host
371 * @dir: DMA transfer direction
372 *
373 * Function finishes with the DMA transfer. After this, the DMA buffer is
374 * unmapped.
375 */
376static void ep93xx_spi_dma_finish(struct spi_controller *host,
377 enum dma_data_direction dir)
378{
379 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
380 struct dma_chan *chan;
381 struct sg_table *sgt;
382
383 if (dir == DMA_FROM_DEVICE) {
384 chan = espi->dma_rx;
385 sgt = &espi->rx_sgt;
386 } else {
387 chan = espi->dma_tx;
388 sgt = &espi->tx_sgt;
389 }
390
391 dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
392}
393
394static void ep93xx_spi_dma_callback(void *callback_param)
395{
396 struct spi_controller *host = callback_param;
397
398 ep93xx_spi_dma_finish(host, DMA_TO_DEVICE);
399 ep93xx_spi_dma_finish(host, DMA_FROM_DEVICE);
400
401 spi_finalize_current_transfer(host);
402}
403
404static int ep93xx_spi_dma_transfer(struct spi_controller *host)
405{
406 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
407 struct dma_async_tx_descriptor *rxd, *txd;
408
409 rxd = ep93xx_spi_dma_prepare(host, DMA_FROM_DEVICE);
410 if (IS_ERR(rxd)) {
411 dev_err(&host->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd));
412 return PTR_ERR(rxd);
413 }
414
415 txd = ep93xx_spi_dma_prepare(host, DMA_TO_DEVICE);
416 if (IS_ERR(txd)) {
417 ep93xx_spi_dma_finish(host, DMA_FROM_DEVICE);
418 dev_err(&host->dev, "DMA TX failed: %ld\n", PTR_ERR(txd));
419 return PTR_ERR(txd);
420 }
421
422 /* We are ready when RX is done */
423 rxd->callback = ep93xx_spi_dma_callback;
424 rxd->callback_param = host;
425
426 /* Now submit both descriptors and start DMA */
427 dmaengine_submit(rxd);
428 dmaengine_submit(txd);
429
430 dma_async_issue_pending(espi->dma_rx);
431 dma_async_issue_pending(espi->dma_tx);
432
433 /* signal that we need to wait for completion */
434 return 1;
435}
436
437static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id)
438{
439 struct spi_controller *host = dev_id;
440 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
441 u32 val;
442
443 /*
444 * If we got ROR (receive overrun) interrupt we know that something is
445 * wrong. Just abort the message.
446 */
447 if (readl(espi->mmio + SSPIIR) & SSPIIR_RORIS) {
448 /* clear the overrun interrupt */
449 writel(0, espi->mmio + SSPICR);
450 dev_warn(&host->dev,
451 "receive overrun, aborting the message\n");
452 host->cur_msg->status = -EIO;
453 } else {
454 /*
455 * Interrupt is either RX (RIS) or TX (TIS). For both cases we
456 * simply execute next data transfer.
457 */
458 if (ep93xx_spi_read_write(host)) {
459 /*
460 * In normal case, there still is some processing left
461 * for current transfer. Let's wait for the next
462 * interrupt then.
463 */
464 return IRQ_HANDLED;
465 }
466 }
467
468 /*
469 * Current transfer is finished, either with error or with success. In
470 * any case we disable interrupts and notify the worker to handle
471 * any post-processing of the message.
472 */
473 val = readl(espi->mmio + SSPCR1);
474 val &= ~(SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
475 writel(val, espi->mmio + SSPCR1);
476
477 spi_finalize_current_transfer(host);
478
479 return IRQ_HANDLED;
480}
481
482static int ep93xx_spi_transfer_one(struct spi_controller *host,
483 struct spi_device *spi,
484 struct spi_transfer *xfer)
485{
486 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
487 u32 val;
488 int ret;
489
490 ret = ep93xx_spi_chip_setup(host, spi, xfer);
491 if (ret) {
492 dev_err(&host->dev, "failed to setup chip for transfer\n");
493 return ret;
494 }
495
496 host->cur_msg->state = xfer;
497 espi->rx = 0;
498 espi->tx = 0;
499
500 /*
501 * There is no point of setting up DMA for the transfers which will
502 * fit into the FIFO and can be transferred with a single interrupt.
503 * So in these cases we will be using PIO and don't bother for DMA.
504 */
505 if (espi->dma_rx && xfer->len > SPI_FIFO_SIZE)
506 return ep93xx_spi_dma_transfer(host);
507
508 /* Using PIO so prime the TX FIFO and enable interrupts */
509 ep93xx_spi_read_write(host);
510
511 val = readl(espi->mmio + SSPCR1);
512 val |= (SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
513 writel(val, espi->mmio + SSPCR1);
514
515 /* signal that we need to wait for completion */
516 return 1;
517}
518
519static int ep93xx_spi_prepare_message(struct spi_controller *host,
520 struct spi_message *msg)
521{
522 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
523 unsigned long timeout;
524
525 /*
526 * Just to be sure: flush any data from RX FIFO.
527 */
528 timeout = jiffies + msecs_to_jiffies(SPI_TIMEOUT);
529 while (readl(espi->mmio + SSPSR) & SSPSR_RNE) {
530 if (time_after(jiffies, timeout)) {
531 dev_warn(&host->dev,
532 "timeout while flushing RX FIFO\n");
533 return -ETIMEDOUT;
534 }
535 readl(espi->mmio + SSPDR);
536 }
537
538 /*
539 * We explicitly handle FIFO level. This way we don't have to check TX
540 * FIFO status using %SSPSR_TNF bit which may cause RX FIFO overruns.
541 */
542 espi->fifo_level = 0;
543
544 return 0;
545}
546
547static int ep93xx_spi_prepare_hardware(struct spi_controller *host)
548{
549 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
550 u32 val;
551 int ret;
552
553 ret = clk_prepare_enable(espi->clk);
554 if (ret)
555 return ret;
556
557 val = readl(espi->mmio + SSPCR1);
558 val |= SSPCR1_SSE;
559 writel(val, espi->mmio + SSPCR1);
560
561 return 0;
562}
563
564static int ep93xx_spi_unprepare_hardware(struct spi_controller *host)
565{
566 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
567 u32 val;
568
569 val = readl(espi->mmio + SSPCR1);
570 val &= ~SSPCR1_SSE;
571 writel(val, espi->mmio + SSPCR1);
572
573 clk_disable_unprepare(espi->clk);
574
575 return 0;
576}
577
578static bool ep93xx_spi_dma_filter(struct dma_chan *chan, void *filter_param)
579{
580 if (ep93xx_dma_chan_is_m2p(chan))
581 return false;
582
583 chan->private = filter_param;
584 return true;
585}
586
587static int ep93xx_spi_setup_dma(struct ep93xx_spi *espi)
588{
589 dma_cap_mask_t mask;
590 int ret;
591
592 espi->zeropage = (void *)get_zeroed_page(GFP_KERNEL);
593 if (!espi->zeropage)
594 return -ENOMEM;
595
596 dma_cap_zero(mask);
597 dma_cap_set(DMA_SLAVE, mask);
598
599 espi->dma_rx_data.port = EP93XX_DMA_SSP;
600 espi->dma_rx_data.direction = DMA_DEV_TO_MEM;
601 espi->dma_rx_data.name = "ep93xx-spi-rx";
602
603 espi->dma_rx = dma_request_channel(mask, ep93xx_spi_dma_filter,
604 &espi->dma_rx_data);
605 if (!espi->dma_rx) {
606 ret = -ENODEV;
607 goto fail_free_page;
608 }
609
610 espi->dma_tx_data.port = EP93XX_DMA_SSP;
611 espi->dma_tx_data.direction = DMA_MEM_TO_DEV;
612 espi->dma_tx_data.name = "ep93xx-spi-tx";
613
614 espi->dma_tx = dma_request_channel(mask, ep93xx_spi_dma_filter,
615 &espi->dma_tx_data);
616 if (!espi->dma_tx) {
617 ret = -ENODEV;
618 goto fail_release_rx;
619 }
620
621 return 0;
622
623fail_release_rx:
624 dma_release_channel(espi->dma_rx);
625 espi->dma_rx = NULL;
626fail_free_page:
627 free_page((unsigned long)espi->zeropage);
628
629 return ret;
630}
631
632static void ep93xx_spi_release_dma(struct ep93xx_spi *espi)
633{
634 if (espi->dma_rx) {
635 dma_release_channel(espi->dma_rx);
636 sg_free_table(&espi->rx_sgt);
637 }
638 if (espi->dma_tx) {
639 dma_release_channel(espi->dma_tx);
640 sg_free_table(&espi->tx_sgt);
641 }
642
643 if (espi->zeropage)
644 free_page((unsigned long)espi->zeropage);
645}
646
647static int ep93xx_spi_probe(struct platform_device *pdev)
648{
649 struct spi_controller *host;
650 struct ep93xx_spi_info *info;
651 struct ep93xx_spi *espi;
652 struct resource *res;
653 int irq;
654 int error;
655
656 info = dev_get_platdata(&pdev->dev);
657 if (!info) {
658 dev_err(&pdev->dev, "missing platform data\n");
659 return -EINVAL;
660 }
661
662 irq = platform_get_irq(pdev, 0);
663 if (irq < 0)
664 return irq;
665
666 host = spi_alloc_host(&pdev->dev, sizeof(*espi));
667 if (!host)
668 return -ENOMEM;
669
670 host->use_gpio_descriptors = true;
671 host->prepare_transfer_hardware = ep93xx_spi_prepare_hardware;
672 host->unprepare_transfer_hardware = ep93xx_spi_unprepare_hardware;
673 host->prepare_message = ep93xx_spi_prepare_message;
674 host->transfer_one = ep93xx_spi_transfer_one;
675 host->bus_num = pdev->id;
676 host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
677 host->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);
678 /*
679 * The SPI core will count the number of GPIO descriptors to figure
680 * out the number of chip selects available on the platform.
681 */
682 host->num_chipselect = 0;
683
684 platform_set_drvdata(pdev, host);
685
686 espi = spi_controller_get_devdata(host);
687
688 espi->clk = devm_clk_get(&pdev->dev, NULL);
689 if (IS_ERR(espi->clk)) {
690 dev_err(&pdev->dev, "unable to get spi clock\n");
691 error = PTR_ERR(espi->clk);
692 goto fail_release_host;
693 }
694
695 /*
696 * Calculate maximum and minimum supported clock rates
697 * for the controller.
698 */
699 host->max_speed_hz = clk_get_rate(espi->clk) / 2;
700 host->min_speed_hz = clk_get_rate(espi->clk) / (254 * 256);
701
702 espi->mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
703 if (IS_ERR(espi->mmio)) {
704 error = PTR_ERR(espi->mmio);
705 goto fail_release_host;
706 }
707 espi->sspdr_phys = res->start + SSPDR;
708
709 error = devm_request_irq(&pdev->dev, irq, ep93xx_spi_interrupt,
710 0, "ep93xx-spi", host);
711 if (error) {
712 dev_err(&pdev->dev, "failed to request irq\n");
713 goto fail_release_host;
714 }
715
716 if (info->use_dma && ep93xx_spi_setup_dma(espi))
717 dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n");
718
719 /* make sure that the hardware is disabled */
720 writel(0, espi->mmio + SSPCR1);
721
722 error = devm_spi_register_controller(&pdev->dev, host);
723 if (error) {
724 dev_err(&pdev->dev, "failed to register SPI host\n");
725 goto fail_free_dma;
726 }
727
728 dev_info(&pdev->dev, "EP93xx SPI Controller at 0x%08lx irq %d\n",
729 (unsigned long)res->start, irq);
730
731 return 0;
732
733fail_free_dma:
734 ep93xx_spi_release_dma(espi);
735fail_release_host:
736 spi_controller_put(host);
737
738 return error;
739}
740
741static void ep93xx_spi_remove(struct platform_device *pdev)
742{
743 struct spi_controller *host = platform_get_drvdata(pdev);
744 struct ep93xx_spi *espi = spi_controller_get_devdata(host);
745
746 ep93xx_spi_release_dma(espi);
747}
748
749static struct platform_driver ep93xx_spi_driver = {
750 .driver = {
751 .name = "ep93xx-spi",
752 },
753 .probe = ep93xx_spi_probe,
754 .remove_new = ep93xx_spi_remove,
755};
756module_platform_driver(ep93xx_spi_driver);
757
758MODULE_DESCRIPTION("EP93xx SPI Controller driver");
759MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
760MODULE_LICENSE("GPL");
761MODULE_ALIAS("platform:ep93xx-spi");
1/*
2 * Driver for Cirrus Logic EP93xx SPI controller.
3 *
4 * Copyright (C) 2010-2011 Mika Westerberg
5 *
6 * Explicit FIFO handling code was inspired by amba-pl022 driver.
7 *
8 * Chip select support using other than built-in GPIOs by H. Hartley Sweeten.
9 *
10 * For more information about the SPI controller see documentation on Cirrus
11 * Logic web site:
12 * http://www.cirrus.com/en/pubs/manual/EP93xx_Users_Guide_UM1.pdf
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License version 2 as
16 * published by the Free Software Foundation.
17 */
18
19#include <linux/io.h>
20#include <linux/clk.h>
21#include <linux/err.h>
22#include <linux/delay.h>
23#include <linux/device.h>
24#include <linux/dmaengine.h>
25#include <linux/bitops.h>
26#include <linux/interrupt.h>
27#include <linux/module.h>
28#include <linux/platform_device.h>
29#include <linux/sched.h>
30#include <linux/scatterlist.h>
31#include <linux/spi/spi.h>
32
33#include <linux/platform_data/dma-ep93xx.h>
34#include <linux/platform_data/spi-ep93xx.h>
35
36#define SSPCR0 0x0000
37#define SSPCR0_MODE_SHIFT 6
38#define SSPCR0_SCR_SHIFT 8
39
40#define SSPCR1 0x0004
41#define SSPCR1_RIE BIT(0)
42#define SSPCR1_TIE BIT(1)
43#define SSPCR1_RORIE BIT(2)
44#define SSPCR1_LBM BIT(3)
45#define SSPCR1_SSE BIT(4)
46#define SSPCR1_MS BIT(5)
47#define SSPCR1_SOD BIT(6)
48
49#define SSPDR 0x0008
50
51#define SSPSR 0x000c
52#define SSPSR_TFE BIT(0)
53#define SSPSR_TNF BIT(1)
54#define SSPSR_RNE BIT(2)
55#define SSPSR_RFF BIT(3)
56#define SSPSR_BSY BIT(4)
57#define SSPCPSR 0x0010
58
59#define SSPIIR 0x0014
60#define SSPIIR_RIS BIT(0)
61#define SSPIIR_TIS BIT(1)
62#define SSPIIR_RORIS BIT(2)
63#define SSPICR SSPIIR
64
65/* timeout in milliseconds */
66#define SPI_TIMEOUT 5
67/* maximum depth of RX/TX FIFO */
68#define SPI_FIFO_SIZE 8
69
70/**
71 * struct ep93xx_spi - EP93xx SPI controller structure
72 * @pdev: pointer to platform device
73 * @clk: clock for the controller
74 * @regs_base: pointer to ioremap()'d registers
75 * @sspdr_phys: physical address of the SSPDR register
76 * @wait: wait here until given transfer is completed
77 * @current_msg: message that is currently processed (or %NULL if none)
78 * @tx: current byte in transfer to transmit
79 * @rx: current byte in transfer to receive
80 * @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one
81 * frame decreases this level and sending one frame increases it.
82 * @dma_rx: RX DMA channel
83 * @dma_tx: TX DMA channel
84 * @dma_rx_data: RX parameters passed to the DMA engine
85 * @dma_tx_data: TX parameters passed to the DMA engine
86 * @rx_sgt: sg table for RX transfers
87 * @tx_sgt: sg table for TX transfers
88 * @zeropage: dummy page used as RX buffer when only TX buffer is passed in by
89 * the client
90 */
91struct ep93xx_spi {
92 const struct platform_device *pdev;
93 struct clk *clk;
94 void __iomem *regs_base;
95 unsigned long sspdr_phys;
96 struct completion wait;
97 struct spi_message *current_msg;
98 size_t tx;
99 size_t rx;
100 size_t fifo_level;
101 struct dma_chan *dma_rx;
102 struct dma_chan *dma_tx;
103 struct ep93xx_dma_data dma_rx_data;
104 struct ep93xx_dma_data dma_tx_data;
105 struct sg_table rx_sgt;
106 struct sg_table tx_sgt;
107 void *zeropage;
108};
109
110/**
111 * struct ep93xx_spi_chip - SPI device hardware settings
112 * @spi: back pointer to the SPI device
113 * @ops: private chip operations
114 */
115struct ep93xx_spi_chip {
116 const struct spi_device *spi;
117 struct ep93xx_spi_chip_ops *ops;
118};
119
120/* converts bits per word to CR0.DSS value */
121#define bits_per_word_to_dss(bpw) ((bpw) - 1)
122
123static void ep93xx_spi_write_u8(const struct ep93xx_spi *espi,
124 u16 reg, u8 value)
125{
126 writeb(value, espi->regs_base + reg);
127}
128
129static u8 ep93xx_spi_read_u8(const struct ep93xx_spi *spi, u16 reg)
130{
131 return readb(spi->regs_base + reg);
132}
133
134static void ep93xx_spi_write_u16(const struct ep93xx_spi *espi,
135 u16 reg, u16 value)
136{
137 writew(value, espi->regs_base + reg);
138}
139
140static u16 ep93xx_spi_read_u16(const struct ep93xx_spi *spi, u16 reg)
141{
142 return readw(spi->regs_base + reg);
143}
144
145static int ep93xx_spi_enable(const struct ep93xx_spi *espi)
146{
147 u8 regval;
148 int err;
149
150 err = clk_enable(espi->clk);
151 if (err)
152 return err;
153
154 regval = ep93xx_spi_read_u8(espi, SSPCR1);
155 regval |= SSPCR1_SSE;
156 ep93xx_spi_write_u8(espi, SSPCR1, regval);
157
158 return 0;
159}
160
161static void ep93xx_spi_disable(const struct ep93xx_spi *espi)
162{
163 u8 regval;
164
165 regval = ep93xx_spi_read_u8(espi, SSPCR1);
166 regval &= ~SSPCR1_SSE;
167 ep93xx_spi_write_u8(espi, SSPCR1, regval);
168
169 clk_disable(espi->clk);
170}
171
172static void ep93xx_spi_enable_interrupts(const struct ep93xx_spi *espi)
173{
174 u8 regval;
175
176 regval = ep93xx_spi_read_u8(espi, SSPCR1);
177 regval |= (SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
178 ep93xx_spi_write_u8(espi, SSPCR1, regval);
179}
180
181static void ep93xx_spi_disable_interrupts(const struct ep93xx_spi *espi)
182{
183 u8 regval;
184
185 regval = ep93xx_spi_read_u8(espi, SSPCR1);
186 regval &= ~(SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE);
187 ep93xx_spi_write_u8(espi, SSPCR1, regval);
188}
189
190/**
191 * ep93xx_spi_calc_divisors() - calculates SPI clock divisors
192 * @espi: ep93xx SPI controller struct
193 * @rate: desired SPI output clock rate
194 * @div_cpsr: pointer to return the cpsr (pre-scaler) divider
195 * @div_scr: pointer to return the scr divider
196 */
197static int ep93xx_spi_calc_divisors(const struct ep93xx_spi *espi,
198 u32 rate, u8 *div_cpsr, u8 *div_scr)
199{
200 struct spi_master *master = platform_get_drvdata(espi->pdev);
201 unsigned long spi_clk_rate = clk_get_rate(espi->clk);
202 int cpsr, scr;
203
204 /*
205 * Make sure that max value is between values supported by the
206 * controller. Note that minimum value is already checked in
207 * ep93xx_spi_transfer_one_message().
208 */
209 rate = clamp(rate, master->min_speed_hz, master->max_speed_hz);
210
211 /*
212 * Calculate divisors so that we can get speed according the
213 * following formula:
214 * rate = spi_clock_rate / (cpsr * (1 + scr))
215 *
216 * cpsr must be even number and starts from 2, scr can be any number
217 * between 0 and 255.
218 */
219 for (cpsr = 2; cpsr <= 254; cpsr += 2) {
220 for (scr = 0; scr <= 255; scr++) {
221 if ((spi_clk_rate / (cpsr * (scr + 1))) <= rate) {
222 *div_scr = (u8)scr;
223 *div_cpsr = (u8)cpsr;
224 return 0;
225 }
226 }
227 }
228
229 return -EINVAL;
230}
231
232static void ep93xx_spi_cs_control(struct spi_device *spi, bool control)
233{
234 struct ep93xx_spi_chip *chip = spi_get_ctldata(spi);
235 int value = (spi->mode & SPI_CS_HIGH) ? control : !control;
236
237 if (chip->ops && chip->ops->cs_control)
238 chip->ops->cs_control(spi, value);
239}
240
241/**
242 * ep93xx_spi_setup() - setup an SPI device
243 * @spi: SPI device to setup
244 *
245 * This function sets up SPI device mode, speed etc. Can be called multiple
246 * times for a single device. Returns %0 in case of success, negative error in
247 * case of failure. When this function returns success, the device is
248 * deselected.
249 */
250static int ep93xx_spi_setup(struct spi_device *spi)
251{
252 struct ep93xx_spi *espi = spi_master_get_devdata(spi->master);
253 struct ep93xx_spi_chip *chip;
254
255 chip = spi_get_ctldata(spi);
256 if (!chip) {
257 dev_dbg(&espi->pdev->dev, "initial setup for %s\n",
258 spi->modalias);
259
260 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
261 if (!chip)
262 return -ENOMEM;
263
264 chip->spi = spi;
265 chip->ops = spi->controller_data;
266
267 if (chip->ops && chip->ops->setup) {
268 int ret = chip->ops->setup(spi);
269
270 if (ret) {
271 kfree(chip);
272 return ret;
273 }
274 }
275
276 spi_set_ctldata(spi, chip);
277 }
278
279 ep93xx_spi_cs_control(spi, false);
280 return 0;
281}
282
283/**
284 * ep93xx_spi_cleanup() - cleans up master controller specific state
285 * @spi: SPI device to cleanup
286 *
287 * This function releases master controller specific state for given @spi
288 * device.
289 */
290static void ep93xx_spi_cleanup(struct spi_device *spi)
291{
292 struct ep93xx_spi_chip *chip;
293
294 chip = spi_get_ctldata(spi);
295 if (chip) {
296 if (chip->ops && chip->ops->cleanup)
297 chip->ops->cleanup(spi);
298 spi_set_ctldata(spi, NULL);
299 kfree(chip);
300 }
301}
302
303/**
304 * ep93xx_spi_chip_setup() - configures hardware according to given @chip
305 * @espi: ep93xx SPI controller struct
306 * @chip: chip specific settings
307 * @speed_hz: transfer speed
308 * @bits_per_word: transfer bits_per_word
309 */
310static int ep93xx_spi_chip_setup(const struct ep93xx_spi *espi,
311 const struct ep93xx_spi_chip *chip,
312 u32 speed_hz, u8 bits_per_word)
313{
314 u8 dss = bits_per_word_to_dss(bits_per_word);
315 u8 div_cpsr = 0;
316 u8 div_scr = 0;
317 u16 cr0;
318 int err;
319
320 err = ep93xx_spi_calc_divisors(espi, speed_hz, &div_cpsr, &div_scr);
321 if (err)
322 return err;
323
324 cr0 = div_scr << SSPCR0_SCR_SHIFT;
325 cr0 |= (chip->spi->mode & (SPI_CPHA|SPI_CPOL)) << SSPCR0_MODE_SHIFT;
326 cr0 |= dss;
327
328 dev_dbg(&espi->pdev->dev, "setup: mode %d, cpsr %d, scr %d, dss %d\n",
329 chip->spi->mode, div_cpsr, div_scr, dss);
330 dev_dbg(&espi->pdev->dev, "setup: cr0 %#x\n", cr0);
331
332 ep93xx_spi_write_u8(espi, SSPCPSR, div_cpsr);
333 ep93xx_spi_write_u16(espi, SSPCR0, cr0);
334
335 return 0;
336}
337
338static void ep93xx_do_write(struct ep93xx_spi *espi, struct spi_transfer *t)
339{
340 if (t->bits_per_word > 8) {
341 u16 tx_val = 0;
342
343 if (t->tx_buf)
344 tx_val = ((u16 *)t->tx_buf)[espi->tx];
345 ep93xx_spi_write_u16(espi, SSPDR, tx_val);
346 espi->tx += sizeof(tx_val);
347 } else {
348 u8 tx_val = 0;
349
350 if (t->tx_buf)
351 tx_val = ((u8 *)t->tx_buf)[espi->tx];
352 ep93xx_spi_write_u8(espi, SSPDR, tx_val);
353 espi->tx += sizeof(tx_val);
354 }
355}
356
357static void ep93xx_do_read(struct ep93xx_spi *espi, struct spi_transfer *t)
358{
359 if (t->bits_per_word > 8) {
360 u16 rx_val;
361
362 rx_val = ep93xx_spi_read_u16(espi, SSPDR);
363 if (t->rx_buf)
364 ((u16 *)t->rx_buf)[espi->rx] = rx_val;
365 espi->rx += sizeof(rx_val);
366 } else {
367 u8 rx_val;
368
369 rx_val = ep93xx_spi_read_u8(espi, SSPDR);
370 if (t->rx_buf)
371 ((u8 *)t->rx_buf)[espi->rx] = rx_val;
372 espi->rx += sizeof(rx_val);
373 }
374}
375
376/**
377 * ep93xx_spi_read_write() - perform next RX/TX transfer
378 * @espi: ep93xx SPI controller struct
379 *
380 * This function transfers next bytes (or half-words) to/from RX/TX FIFOs. If
381 * called several times, the whole transfer will be completed. Returns
382 * %-EINPROGRESS when current transfer was not yet completed otherwise %0.
383 *
384 * When this function is finished, RX FIFO should be empty and TX FIFO should be
385 * full.
386 */
387static int ep93xx_spi_read_write(struct ep93xx_spi *espi)
388{
389 struct spi_message *msg = espi->current_msg;
390 struct spi_transfer *t = msg->state;
391
392 /* read as long as RX FIFO has frames in it */
393 while ((ep93xx_spi_read_u8(espi, SSPSR) & SSPSR_RNE)) {
394 ep93xx_do_read(espi, t);
395 espi->fifo_level--;
396 }
397
398 /* write as long as TX FIFO has room */
399 while (espi->fifo_level < SPI_FIFO_SIZE && espi->tx < t->len) {
400 ep93xx_do_write(espi, t);
401 espi->fifo_level++;
402 }
403
404 if (espi->rx == t->len)
405 return 0;
406
407 return -EINPROGRESS;
408}
409
410static void ep93xx_spi_pio_transfer(struct ep93xx_spi *espi)
411{
412 /*
413 * Now everything is set up for the current transfer. We prime the TX
414 * FIFO, enable interrupts, and wait for the transfer to complete.
415 */
416 if (ep93xx_spi_read_write(espi)) {
417 ep93xx_spi_enable_interrupts(espi);
418 wait_for_completion(&espi->wait);
419 }
420}
421
422/**
423 * ep93xx_spi_dma_prepare() - prepares a DMA transfer
424 * @espi: ep93xx SPI controller struct
425 * @dir: DMA transfer direction
426 *
427 * Function configures the DMA, maps the buffer and prepares the DMA
428 * descriptor. Returns a valid DMA descriptor in case of success and ERR_PTR
429 * in case of failure.
430 */
431static struct dma_async_tx_descriptor *
432ep93xx_spi_dma_prepare(struct ep93xx_spi *espi, enum dma_transfer_direction dir)
433{
434 struct spi_transfer *t = espi->current_msg->state;
435 struct dma_async_tx_descriptor *txd;
436 enum dma_slave_buswidth buswidth;
437 struct dma_slave_config conf;
438 struct scatterlist *sg;
439 struct sg_table *sgt;
440 struct dma_chan *chan;
441 const void *buf, *pbuf;
442 size_t len = t->len;
443 int i, ret, nents;
444
445 if (t->bits_per_word > 8)
446 buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
447 else
448 buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
449
450 memset(&conf, 0, sizeof(conf));
451 conf.direction = dir;
452
453 if (dir == DMA_DEV_TO_MEM) {
454 chan = espi->dma_rx;
455 buf = t->rx_buf;
456 sgt = &espi->rx_sgt;
457
458 conf.src_addr = espi->sspdr_phys;
459 conf.src_addr_width = buswidth;
460 } else {
461 chan = espi->dma_tx;
462 buf = t->tx_buf;
463 sgt = &espi->tx_sgt;
464
465 conf.dst_addr = espi->sspdr_phys;
466 conf.dst_addr_width = buswidth;
467 }
468
469 ret = dmaengine_slave_config(chan, &conf);
470 if (ret)
471 return ERR_PTR(ret);
472
473 /*
474 * We need to split the transfer into PAGE_SIZE'd chunks. This is
475 * because we are using @espi->zeropage to provide a zero RX buffer
476 * for the TX transfers and we have only allocated one page for that.
477 *
478 * For performance reasons we allocate a new sg_table only when
479 * needed. Otherwise we will re-use the current one. Eventually the
480 * last sg_table is released in ep93xx_spi_release_dma().
481 */
482
483 nents = DIV_ROUND_UP(len, PAGE_SIZE);
484 if (nents != sgt->nents) {
485 sg_free_table(sgt);
486
487 ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
488 if (ret)
489 return ERR_PTR(ret);
490 }
491
492 pbuf = buf;
493 for_each_sg(sgt->sgl, sg, sgt->nents, i) {
494 size_t bytes = min_t(size_t, len, PAGE_SIZE);
495
496 if (buf) {
497 sg_set_page(sg, virt_to_page(pbuf), bytes,
498 offset_in_page(pbuf));
499 } else {
500 sg_set_page(sg, virt_to_page(espi->zeropage),
501 bytes, 0);
502 }
503
504 pbuf += bytes;
505 len -= bytes;
506 }
507
508 if (WARN_ON(len)) {
509 dev_warn(&espi->pdev->dev, "len = %zu expected 0!\n", len);
510 return ERR_PTR(-EINVAL);
511 }
512
513 nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
514 if (!nents)
515 return ERR_PTR(-ENOMEM);
516
517 txd = dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir, DMA_CTRL_ACK);
518 if (!txd) {
519 dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
520 return ERR_PTR(-ENOMEM);
521 }
522 return txd;
523}
524
525/**
526 * ep93xx_spi_dma_finish() - finishes with a DMA transfer
527 * @espi: ep93xx SPI controller struct
528 * @dir: DMA transfer direction
529 *
530 * Function finishes with the DMA transfer. After this, the DMA buffer is
531 * unmapped.
532 */
533static void ep93xx_spi_dma_finish(struct ep93xx_spi *espi,
534 enum dma_transfer_direction dir)
535{
536 struct dma_chan *chan;
537 struct sg_table *sgt;
538
539 if (dir == DMA_DEV_TO_MEM) {
540 chan = espi->dma_rx;
541 sgt = &espi->rx_sgt;
542 } else {
543 chan = espi->dma_tx;
544 sgt = &espi->tx_sgt;
545 }
546
547 dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
548}
549
550static void ep93xx_spi_dma_callback(void *callback_param)
551{
552 complete(callback_param);
553}
554
555static void ep93xx_spi_dma_transfer(struct ep93xx_spi *espi)
556{
557 struct spi_message *msg = espi->current_msg;
558 struct dma_async_tx_descriptor *rxd, *txd;
559
560 rxd = ep93xx_spi_dma_prepare(espi, DMA_DEV_TO_MEM);
561 if (IS_ERR(rxd)) {
562 dev_err(&espi->pdev->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd));
563 msg->status = PTR_ERR(rxd);
564 return;
565 }
566
567 txd = ep93xx_spi_dma_prepare(espi, DMA_MEM_TO_DEV);
568 if (IS_ERR(txd)) {
569 ep93xx_spi_dma_finish(espi, DMA_DEV_TO_MEM);
570 dev_err(&espi->pdev->dev, "DMA TX failed: %ld\n", PTR_ERR(rxd));
571 msg->status = PTR_ERR(txd);
572 return;
573 }
574
575 /* We are ready when RX is done */
576 rxd->callback = ep93xx_spi_dma_callback;
577 rxd->callback_param = &espi->wait;
578
579 /* Now submit both descriptors and wait while they finish */
580 dmaengine_submit(rxd);
581 dmaengine_submit(txd);
582
583 dma_async_issue_pending(espi->dma_rx);
584 dma_async_issue_pending(espi->dma_tx);
585
586 wait_for_completion(&espi->wait);
587
588 ep93xx_spi_dma_finish(espi, DMA_MEM_TO_DEV);
589 ep93xx_spi_dma_finish(espi, DMA_DEV_TO_MEM);
590}
591
592/**
593 * ep93xx_spi_process_transfer() - processes one SPI transfer
594 * @espi: ep93xx SPI controller struct
595 * @msg: current message
596 * @t: transfer to process
597 *
598 * This function processes one SPI transfer given in @t. Function waits until
599 * transfer is complete (may sleep) and updates @msg->status based on whether
600 * transfer was successfully processed or not.
601 */
602static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi,
603 struct spi_message *msg,
604 struct spi_transfer *t)
605{
606 struct ep93xx_spi_chip *chip = spi_get_ctldata(msg->spi);
607 int err;
608
609 msg->state = t;
610
611 err = ep93xx_spi_chip_setup(espi, chip, t->speed_hz, t->bits_per_word);
612 if (err) {
613 dev_err(&espi->pdev->dev,
614 "failed to setup chip for transfer\n");
615 msg->status = err;
616 return;
617 }
618
619 espi->rx = 0;
620 espi->tx = 0;
621
622 /*
623 * There is no point of setting up DMA for the transfers which will
624 * fit into the FIFO and can be transferred with a single interrupt.
625 * So in these cases we will be using PIO and don't bother for DMA.
626 */
627 if (espi->dma_rx && t->len > SPI_FIFO_SIZE)
628 ep93xx_spi_dma_transfer(espi);
629 else
630 ep93xx_spi_pio_transfer(espi);
631
632 /*
633 * In case of error during transmit, we bail out from processing
634 * the message.
635 */
636 if (msg->status)
637 return;
638
639 msg->actual_length += t->len;
640
641 /*
642 * After this transfer is finished, perform any possible
643 * post-transfer actions requested by the protocol driver.
644 */
645 if (t->delay_usecs) {
646 set_current_state(TASK_UNINTERRUPTIBLE);
647 schedule_timeout(usecs_to_jiffies(t->delay_usecs));
648 }
649 if (t->cs_change) {
650 if (!list_is_last(&t->transfer_list, &msg->transfers)) {
651 /*
652 * In case protocol driver is asking us to drop the
653 * chipselect briefly, we let the scheduler to handle
654 * any "delay" here.
655 */
656 ep93xx_spi_cs_control(msg->spi, false);
657 cond_resched();
658 ep93xx_spi_cs_control(msg->spi, true);
659 }
660 }
661}
662
663/*
664 * ep93xx_spi_process_message() - process one SPI message
665 * @espi: ep93xx SPI controller struct
666 * @msg: message to process
667 *
668 * This function processes a single SPI message. We go through all transfers in
669 * the message and pass them to ep93xx_spi_process_transfer(). Chipselect is
670 * asserted during the whole message (unless per transfer cs_change is set).
671 *
672 * @msg->status contains %0 in case of success or negative error code in case of
673 * failure.
674 */
675static void ep93xx_spi_process_message(struct ep93xx_spi *espi,
676 struct spi_message *msg)
677{
678 unsigned long timeout;
679 struct spi_transfer *t;
680 int err;
681
682 /*
683 * Enable the SPI controller and its clock.
684 */
685 err = ep93xx_spi_enable(espi);
686 if (err) {
687 dev_err(&espi->pdev->dev, "failed to enable SPI controller\n");
688 msg->status = err;
689 return;
690 }
691
692 /*
693 * Just to be sure: flush any data from RX FIFO.
694 */
695 timeout = jiffies + msecs_to_jiffies(SPI_TIMEOUT);
696 while (ep93xx_spi_read_u16(espi, SSPSR) & SSPSR_RNE) {
697 if (time_after(jiffies, timeout)) {
698 dev_warn(&espi->pdev->dev,
699 "timeout while flushing RX FIFO\n");
700 msg->status = -ETIMEDOUT;
701 return;
702 }
703 ep93xx_spi_read_u16(espi, SSPDR);
704 }
705
706 /*
707 * We explicitly handle FIFO level. This way we don't have to check TX
708 * FIFO status using %SSPSR_TNF bit which may cause RX FIFO overruns.
709 */
710 espi->fifo_level = 0;
711
712 /*
713 * Assert the chipselect.
714 */
715 ep93xx_spi_cs_control(msg->spi, true);
716
717 list_for_each_entry(t, &msg->transfers, transfer_list) {
718 ep93xx_spi_process_transfer(espi, msg, t);
719 if (msg->status)
720 break;
721 }
722
723 /*
724 * Now the whole message is transferred (or failed for some reason). We
725 * deselect the device and disable the SPI controller.
726 */
727 ep93xx_spi_cs_control(msg->spi, false);
728 ep93xx_spi_disable(espi);
729}
730
731static int ep93xx_spi_transfer_one_message(struct spi_master *master,
732 struct spi_message *msg)
733{
734 struct ep93xx_spi *espi = spi_master_get_devdata(master);
735
736 msg->state = NULL;
737 msg->status = 0;
738 msg->actual_length = 0;
739
740 espi->current_msg = msg;
741 ep93xx_spi_process_message(espi, msg);
742 espi->current_msg = NULL;
743
744 spi_finalize_current_message(master);
745
746 return 0;
747}
748
749static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id)
750{
751 struct ep93xx_spi *espi = dev_id;
752 u8 irq_status = ep93xx_spi_read_u8(espi, SSPIIR);
753
754 /*
755 * If we got ROR (receive overrun) interrupt we know that something is
756 * wrong. Just abort the message.
757 */
758 if (unlikely(irq_status & SSPIIR_RORIS)) {
759 /* clear the overrun interrupt */
760 ep93xx_spi_write_u8(espi, SSPICR, 0);
761 dev_warn(&espi->pdev->dev,
762 "receive overrun, aborting the message\n");
763 espi->current_msg->status = -EIO;
764 } else {
765 /*
766 * Interrupt is either RX (RIS) or TX (TIS). For both cases we
767 * simply execute next data transfer.
768 */
769 if (ep93xx_spi_read_write(espi)) {
770 /*
771 * In normal case, there still is some processing left
772 * for current transfer. Let's wait for the next
773 * interrupt then.
774 */
775 return IRQ_HANDLED;
776 }
777 }
778
779 /*
780 * Current transfer is finished, either with error or with success. In
781 * any case we disable interrupts and notify the worker to handle
782 * any post-processing of the message.
783 */
784 ep93xx_spi_disable_interrupts(espi);
785 complete(&espi->wait);
786 return IRQ_HANDLED;
787}
788
789static bool ep93xx_spi_dma_filter(struct dma_chan *chan, void *filter_param)
790{
791 if (ep93xx_dma_chan_is_m2p(chan))
792 return false;
793
794 chan->private = filter_param;
795 return true;
796}
797
798static int ep93xx_spi_setup_dma(struct ep93xx_spi *espi)
799{
800 dma_cap_mask_t mask;
801 int ret;
802
803 espi->zeropage = (void *)get_zeroed_page(GFP_KERNEL);
804 if (!espi->zeropage)
805 return -ENOMEM;
806
807 dma_cap_zero(mask);
808 dma_cap_set(DMA_SLAVE, mask);
809
810 espi->dma_rx_data.port = EP93XX_DMA_SSP;
811 espi->dma_rx_data.direction = DMA_DEV_TO_MEM;
812 espi->dma_rx_data.name = "ep93xx-spi-rx";
813
814 espi->dma_rx = dma_request_channel(mask, ep93xx_spi_dma_filter,
815 &espi->dma_rx_data);
816 if (!espi->dma_rx) {
817 ret = -ENODEV;
818 goto fail_free_page;
819 }
820
821 espi->dma_tx_data.port = EP93XX_DMA_SSP;
822 espi->dma_tx_data.direction = DMA_MEM_TO_DEV;
823 espi->dma_tx_data.name = "ep93xx-spi-tx";
824
825 espi->dma_tx = dma_request_channel(mask, ep93xx_spi_dma_filter,
826 &espi->dma_tx_data);
827 if (!espi->dma_tx) {
828 ret = -ENODEV;
829 goto fail_release_rx;
830 }
831
832 return 0;
833
834fail_release_rx:
835 dma_release_channel(espi->dma_rx);
836 espi->dma_rx = NULL;
837fail_free_page:
838 free_page((unsigned long)espi->zeropage);
839
840 return ret;
841}
842
843static void ep93xx_spi_release_dma(struct ep93xx_spi *espi)
844{
845 if (espi->dma_rx) {
846 dma_release_channel(espi->dma_rx);
847 sg_free_table(&espi->rx_sgt);
848 }
849 if (espi->dma_tx) {
850 dma_release_channel(espi->dma_tx);
851 sg_free_table(&espi->tx_sgt);
852 }
853
854 if (espi->zeropage)
855 free_page((unsigned long)espi->zeropage);
856}
857
858static int ep93xx_spi_probe(struct platform_device *pdev)
859{
860 struct spi_master *master;
861 struct ep93xx_spi_info *info;
862 struct ep93xx_spi *espi;
863 struct resource *res;
864 int irq;
865 int error;
866
867 info = dev_get_platdata(&pdev->dev);
868
869 irq = platform_get_irq(pdev, 0);
870 if (irq < 0) {
871 dev_err(&pdev->dev, "failed to get irq resources\n");
872 return -EBUSY;
873 }
874
875 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
876 if (!res) {
877 dev_err(&pdev->dev, "unable to get iomem resource\n");
878 return -ENODEV;
879 }
880
881 master = spi_alloc_master(&pdev->dev, sizeof(*espi));
882 if (!master)
883 return -ENOMEM;
884
885 master->setup = ep93xx_spi_setup;
886 master->transfer_one_message = ep93xx_spi_transfer_one_message;
887 master->cleanup = ep93xx_spi_cleanup;
888 master->bus_num = pdev->id;
889 master->num_chipselect = info->num_chipselect;
890 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
891 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);
892
893 platform_set_drvdata(pdev, master);
894
895 espi = spi_master_get_devdata(master);
896
897 espi->clk = devm_clk_get(&pdev->dev, NULL);
898 if (IS_ERR(espi->clk)) {
899 dev_err(&pdev->dev, "unable to get spi clock\n");
900 error = PTR_ERR(espi->clk);
901 goto fail_release_master;
902 }
903
904 init_completion(&espi->wait);
905
906 /*
907 * Calculate maximum and minimum supported clock rates
908 * for the controller.
909 */
910 master->max_speed_hz = clk_get_rate(espi->clk) / 2;
911 master->min_speed_hz = clk_get_rate(espi->clk) / (254 * 256);
912 espi->pdev = pdev;
913
914 espi->sspdr_phys = res->start + SSPDR;
915
916 espi->regs_base = devm_ioremap_resource(&pdev->dev, res);
917 if (IS_ERR(espi->regs_base)) {
918 error = PTR_ERR(espi->regs_base);
919 goto fail_release_master;
920 }
921
922 error = devm_request_irq(&pdev->dev, irq, ep93xx_spi_interrupt,
923 0, "ep93xx-spi", espi);
924 if (error) {
925 dev_err(&pdev->dev, "failed to request irq\n");
926 goto fail_release_master;
927 }
928
929 if (info->use_dma && ep93xx_spi_setup_dma(espi))
930 dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n");
931
932 /* make sure that the hardware is disabled */
933 ep93xx_spi_write_u8(espi, SSPCR1, 0);
934
935 error = devm_spi_register_master(&pdev->dev, master);
936 if (error) {
937 dev_err(&pdev->dev, "failed to register SPI master\n");
938 goto fail_free_dma;
939 }
940
941 dev_info(&pdev->dev, "EP93xx SPI Controller at 0x%08lx irq %d\n",
942 (unsigned long)res->start, irq);
943
944 return 0;
945
946fail_free_dma:
947 ep93xx_spi_release_dma(espi);
948fail_release_master:
949 spi_master_put(master);
950
951 return error;
952}
953
954static int ep93xx_spi_remove(struct platform_device *pdev)
955{
956 struct spi_master *master = platform_get_drvdata(pdev);
957 struct ep93xx_spi *espi = spi_master_get_devdata(master);
958
959 ep93xx_spi_release_dma(espi);
960
961 return 0;
962}
963
964static struct platform_driver ep93xx_spi_driver = {
965 .driver = {
966 .name = "ep93xx-spi",
967 },
968 .probe = ep93xx_spi_probe,
969 .remove = ep93xx_spi_remove,
970};
971module_platform_driver(ep93xx_spi_driver);
972
973MODULE_DESCRIPTION("EP93xx SPI Controller driver");
974MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
975MODULE_LICENSE("GPL");
976MODULE_ALIAS("platform:ep93xx-spi");