1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Microchip PIC32 SPI controller driver.
4 *
5 * Purna Chandra Mandal <purna.mandal@microchip.com>
6 * Copyright (c) 2016, Microchip Technology Inc.
7 */
8
9 #include <linux/clk.h>
10 #include <linux/clkdev.h>
11 #include <linux/delay.h>
12 #include <linux/dmaengine.h>
13 #include <linux/dma-mapping.h>
14 #include <linux/highmem.h>
15 #include <linux/module.h>
16 #include <linux/io.h>
17 #include <linux/interrupt.h>
18 #include <linux/of.h>
19 #include <linux/of_irq.h>
20 #include <linux/of_gpio.h>
21 #include <linux/of_address.h>
22 #include <linux/platform_device.h>
23 #include <linux/spi/spi.h>
24
25 /* SPI controller registers */
26 struct pic32_spi_regs {
27 u32 ctrl;
28 u32 ctrl_clr;
29 u32 ctrl_set;
30 u32 ctrl_inv;
31 u32 status;
32 u32 status_clr;
33 u32 status_set;
34 u32 status_inv;
35 u32 buf;
36 u32 dontuse[3];
37 u32 baud;
38 u32 dontuse2[3];
39 u32 ctrl2;
40 u32 ctrl2_clr;
41 u32 ctrl2_set;
42 u32 ctrl2_inv;
43 };
44
45 /* Bit fields of SPI Control Register */
46 #define CTRL_RX_INT_SHIFT 0 /* Rx interrupt generation */
47 #define RX_FIFO_EMPTY 0
48 #define RX_FIFO_NOT_EMPTY 1 /* not empty */
49 #define RX_FIFO_HALF_FULL 2 /* full by half or more */
50 #define RX_FIFO_FULL 3 /* completely full */
51
52 #define CTRL_TX_INT_SHIFT 2 /* TX interrupt generation */
53 #define TX_FIFO_ALL_EMPTY 0 /* completely empty */
54 #define TX_FIFO_EMPTY 1 /* empty */
55 #define TX_FIFO_HALF_EMPTY 2 /* empty by half or more */
56 #define TX_FIFO_NOT_FULL 3 /* atleast one empty */
57
58 #define CTRL_MSTEN BIT(5) /* enable master mode */
59 #define CTRL_CKP BIT(6) /* active low */
60 #define CTRL_CKE BIT(8) /* Tx on falling edge */
61 #define CTRL_SMP BIT(9) /* Rx at middle or end of tx */
62 #define CTRL_BPW_MASK 0x03 /* bits per word/sample */
63 #define CTRL_BPW_SHIFT 10
64 #define PIC32_BPW_8 0
65 #define PIC32_BPW_16 1
66 #define PIC32_BPW_32 2
67 #define CTRL_SIDL BIT(13) /* sleep when idle */
68 #define CTRL_ON BIT(15) /* enable macro */
69 #define CTRL_ENHBUF BIT(16) /* enable enhanced buffering */
70 #define CTRL_MCLKSEL BIT(23) /* select clock source */
71 #define CTRL_MSSEN BIT(28) /* macro driven /SS */
72 #define CTRL_FRMEN BIT(31) /* enable framing mode */
73
74 /* Bit fields of SPI Status Register */
75 #define STAT_RF_EMPTY BIT(5) /* RX Fifo empty */
76 #define STAT_RX_OV BIT(6) /* err, s/w needs to clear */
77 #define STAT_TX_UR BIT(8) /* UR in Framed SPI modes */
78 #define STAT_FRM_ERR BIT(12) /* Multiple Frame Sync pulse */
79 #define STAT_TF_LVL_MASK 0x1F
80 #define STAT_TF_LVL_SHIFT 16
81 #define STAT_RF_LVL_MASK 0x1F
82 #define STAT_RF_LVL_SHIFT 24
83
84 /* Bit fields of SPI Baud Register */
85 #define BAUD_MASK 0x1ff
86
87 /* Bit fields of SPI Control2 Register */
88 #define CTRL2_TX_UR_EN BIT(10) /* Enable int on Tx under-run */
89 #define CTRL2_RX_OV_EN BIT(11) /* Enable int on Rx over-run */
90 #define CTRL2_FRM_ERR_EN BIT(12) /* Enable frame err int */
91
92 /* Minimum DMA transfer size */
93 #define PIC32_DMA_LEN_MIN 64
94
95 struct pic32_spi {
96 dma_addr_t dma_base;
97 struct pic32_spi_regs __iomem *regs;
98 int fault_irq;
99 int rx_irq;
100 int tx_irq;
101 u32 fifo_n_byte; /* FIFO depth in bytes */
102 struct clk *clk;
103 struct spi_master *master;
104 /* Current controller setting */
105 u32 speed_hz; /* spi-clk rate */
106 u32 mode;
107 u32 bits_per_word;
108 u32 fifo_n_elm; /* FIFO depth in words */
109 #define PIC32F_DMA_PREP 0 /* DMA chnls configured */
110 unsigned long flags;
111 /* Current transfer state */
112 struct completion xfer_done;
113 /* PIO transfer specific */
114 const void *tx;
115 const void *tx_end;
116 const void *rx;
117 const void *rx_end;
118 int len;
119 void (*rx_fifo)(struct pic32_spi *);
120 void (*tx_fifo)(struct pic32_spi *);
121 };
122
pic32_spi_enable(struct pic32_spi * pic32s)123 static inline void pic32_spi_enable(struct pic32_spi *pic32s)
124 {
125 writel(CTRL_ON | CTRL_SIDL, &pic32s->regs->ctrl_set);
126 }
127
pic32_spi_disable(struct pic32_spi * pic32s)128 static inline void pic32_spi_disable(struct pic32_spi *pic32s)
129 {
130 writel(CTRL_ON | CTRL_SIDL, &pic32s->regs->ctrl_clr);
131
132 /* avoid SPI registers read/write at immediate next CPU clock */
133 ndelay(20);
134 }
135
pic32_spi_set_clk_rate(struct pic32_spi * pic32s,u32 spi_ck)136 static void pic32_spi_set_clk_rate(struct pic32_spi *pic32s, u32 spi_ck)
137 {
138 u32 div;
139
140 /* div = (clk_in / 2 * spi_ck) - 1 */
141 div = DIV_ROUND_CLOSEST(clk_get_rate(pic32s->clk), 2 * spi_ck) - 1;
142
143 writel(div & BAUD_MASK, &pic32s->regs->baud);
144 }
145
pic32_rx_fifo_level(struct pic32_spi * pic32s)146 static inline u32 pic32_rx_fifo_level(struct pic32_spi *pic32s)
147 {
148 u32 sr = readl(&pic32s->regs->status);
149
150 return (sr >> STAT_RF_LVL_SHIFT) & STAT_RF_LVL_MASK;
151 }
152
pic32_tx_fifo_level(struct pic32_spi * pic32s)153 static inline u32 pic32_tx_fifo_level(struct pic32_spi *pic32s)
154 {
155 u32 sr = readl(&pic32s->regs->status);
156
157 return (sr >> STAT_TF_LVL_SHIFT) & STAT_TF_LVL_MASK;
158 }
159
160 /* Return the max entries we can fill into tx fifo */
pic32_tx_max(struct pic32_spi * pic32s,int n_bytes)161 static u32 pic32_tx_max(struct pic32_spi *pic32s, int n_bytes)
162 {
163 u32 tx_left, tx_room, rxtx_gap;
164
165 tx_left = (pic32s->tx_end - pic32s->tx) / n_bytes;
166 tx_room = pic32s->fifo_n_elm - pic32_tx_fifo_level(pic32s);
167
168 /*
169 * Another concern is about the tx/rx mismatch, we
170 * though to use (pic32s->fifo_n_byte - rxfl - txfl) as
171 * one maximum value for tx, but it doesn't cover the
172 * data which is out of tx/rx fifo and inside the
173 * shift registers. So a ctrl from sw point of
174 * view is taken.
175 */
176 rxtx_gap = ((pic32s->rx_end - pic32s->rx) -
177 (pic32s->tx_end - pic32s->tx)) / n_bytes;
178 return min3(tx_left, tx_room, (u32)(pic32s->fifo_n_elm - rxtx_gap));
179 }
180
181 /* Return the max entries we should read out of rx fifo */
pic32_rx_max(struct pic32_spi * pic32s,int n_bytes)182 static u32 pic32_rx_max(struct pic32_spi *pic32s, int n_bytes)
183 {
184 u32 rx_left = (pic32s->rx_end - pic32s->rx) / n_bytes;
185
186 return min_t(u32, rx_left, pic32_rx_fifo_level(pic32s));
187 }
188
189 #define BUILD_SPI_FIFO_RW(__name, __type, __bwl) \
190 static void pic32_spi_rx_##__name(struct pic32_spi *pic32s) \
191 { \
192 __type v; \
193 u32 mx = pic32_rx_max(pic32s, sizeof(__type)); \
194 for (; mx; mx--) { \
195 v = read##__bwl(&pic32s->regs->buf); \
196 if (pic32s->rx_end - pic32s->len) \
197 *(__type *)(pic32s->rx) = v; \
198 pic32s->rx += sizeof(__type); \
199 } \
200 } \
201 \
202 static void pic32_spi_tx_##__name(struct pic32_spi *pic32s) \
203 { \
204 __type v; \
205 u32 mx = pic32_tx_max(pic32s, sizeof(__type)); \
206 for (; mx ; mx--) { \
207 v = (__type)~0U; \
208 if (pic32s->tx_end - pic32s->len) \
209 v = *(__type *)(pic32s->tx); \
210 write##__bwl(v, &pic32s->regs->buf); \
211 pic32s->tx += sizeof(__type); \
212 } \
213 }
214
215 BUILD_SPI_FIFO_RW(byte, u8, b);
216 BUILD_SPI_FIFO_RW(word, u16, w);
217 BUILD_SPI_FIFO_RW(dword, u32, l);
218
pic32_err_stop(struct pic32_spi * pic32s,const char * msg)219 static void pic32_err_stop(struct pic32_spi *pic32s, const char *msg)
220 {
221 /* disable all interrupts */
222 disable_irq_nosync(pic32s->fault_irq);
223 disable_irq_nosync(pic32s->rx_irq);
224 disable_irq_nosync(pic32s->tx_irq);
225
226 /* Show err message and abort xfer with err */
227 dev_err(&pic32s->master->dev, "%s\n", msg);
228 if (pic32s->master->cur_msg)
229 pic32s->master->cur_msg->status = -EIO;
230 complete(&pic32s->xfer_done);
231 }
232
pic32_spi_fault_irq(int irq,void * dev_id)233 static irqreturn_t pic32_spi_fault_irq(int irq, void *dev_id)
234 {
235 struct pic32_spi *pic32s = dev_id;
236 u32 status;
237
238 status = readl(&pic32s->regs->status);
239
240 /* Error handling */
241 if (status & (STAT_RX_OV | STAT_TX_UR)) {
242 writel(STAT_RX_OV, &pic32s->regs->status_clr);
243 writel(STAT_TX_UR, &pic32s->regs->status_clr);
244 pic32_err_stop(pic32s, "err_irq: fifo ov/ur-run\n");
245 return IRQ_HANDLED;
246 }
247
248 if (status & STAT_FRM_ERR) {
249 pic32_err_stop(pic32s, "err_irq: frame error");
250 return IRQ_HANDLED;
251 }
252
253 if (!pic32s->master->cur_msg) {
254 pic32_err_stop(pic32s, "err_irq: no mesg");
255 return IRQ_NONE;
256 }
257
258 return IRQ_NONE;
259 }
260
pic32_spi_rx_irq(int irq,void * dev_id)261 static irqreturn_t pic32_spi_rx_irq(int irq, void *dev_id)
262 {
263 struct pic32_spi *pic32s = dev_id;
264
265 pic32s->rx_fifo(pic32s);
266
267 /* rx complete ? */
268 if (pic32s->rx_end == pic32s->rx) {
269 /* disable all interrupts */
270 disable_irq_nosync(pic32s->fault_irq);
271 disable_irq_nosync(pic32s->rx_irq);
272
273 /* complete current xfer */
274 complete(&pic32s->xfer_done);
275 }
276
277 return IRQ_HANDLED;
278 }
279
pic32_spi_tx_irq(int irq,void * dev_id)280 static irqreturn_t pic32_spi_tx_irq(int irq, void *dev_id)
281 {
282 struct pic32_spi *pic32s = dev_id;
283
284 pic32s->tx_fifo(pic32s);
285
286 /* tx complete? disable tx interrupt */
287 if (pic32s->tx_end == pic32s->tx)
288 disable_irq_nosync(pic32s->tx_irq);
289
290 return IRQ_HANDLED;
291 }
292
pic32_spi_dma_rx_notify(void * data)293 static void pic32_spi_dma_rx_notify(void *data)
294 {
295 struct pic32_spi *pic32s = data;
296
297 complete(&pic32s->xfer_done);
298 }
299
pic32_spi_dma_transfer(struct pic32_spi * pic32s,struct spi_transfer * xfer)300 static int pic32_spi_dma_transfer(struct pic32_spi *pic32s,
301 struct spi_transfer *xfer)
302 {
303 struct spi_master *master = pic32s->master;
304 struct dma_async_tx_descriptor *desc_rx;
305 struct dma_async_tx_descriptor *desc_tx;
306 dma_cookie_t cookie;
307 int ret;
308
309 if (!master->dma_rx || !master->dma_tx)
310 return -ENODEV;
311
312 desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
313 xfer->rx_sg.sgl,
314 xfer->rx_sg.nents,
315 DMA_DEV_TO_MEM,
316 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
317 if (!desc_rx) {
318 ret = -EINVAL;
319 goto err_dma;
320 }
321
322 desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
323 xfer->tx_sg.sgl,
324 xfer->tx_sg.nents,
325 DMA_MEM_TO_DEV,
326 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
327 if (!desc_tx) {
328 ret = -EINVAL;
329 goto err_dma;
330 }
331
332 /* Put callback on the RX transfer, that should finish last */
333 desc_rx->callback = pic32_spi_dma_rx_notify;
334 desc_rx->callback_param = pic32s;
335
336 cookie = dmaengine_submit(desc_rx);
337 ret = dma_submit_error(cookie);
338 if (ret)
339 goto err_dma;
340
341 cookie = dmaengine_submit(desc_tx);
342 ret = dma_submit_error(cookie);
343 if (ret)
344 goto err_dma_tx;
345
346 dma_async_issue_pending(master->dma_rx);
347 dma_async_issue_pending(master->dma_tx);
348
349 return 0;
350
351 err_dma_tx:
352 dmaengine_terminate_all(master->dma_rx);
353 err_dma:
354 return ret;
355 }
356
pic32_spi_dma_config(struct pic32_spi * pic32s,u32 dma_width)357 static int pic32_spi_dma_config(struct pic32_spi *pic32s, u32 dma_width)
358 {
359 int buf_offset = offsetof(struct pic32_spi_regs, buf);
360 struct spi_master *master = pic32s->master;
361 struct dma_slave_config cfg;
362 int ret;
363
364 cfg.device_fc = true;
365 cfg.src_addr = pic32s->dma_base + buf_offset;
366 cfg.dst_addr = pic32s->dma_base + buf_offset;
367 cfg.src_maxburst = pic32s->fifo_n_elm / 2; /* fill one-half */
368 cfg.dst_maxburst = pic32s->fifo_n_elm / 2; /* drain one-half */
369 cfg.src_addr_width = dma_width;
370 cfg.dst_addr_width = dma_width;
371 /* tx channel */
372 cfg.slave_id = pic32s->tx_irq;
373 cfg.direction = DMA_MEM_TO_DEV;
374 ret = dmaengine_slave_config(master->dma_tx, &cfg);
375 if (ret) {
376 dev_err(&master->dev, "tx channel setup failed\n");
377 return ret;
378 }
379 /* rx channel */
380 cfg.slave_id = pic32s->rx_irq;
381 cfg.direction = DMA_DEV_TO_MEM;
382 ret = dmaengine_slave_config(master->dma_rx, &cfg);
383 if (ret)
384 dev_err(&master->dev, "rx channel setup failed\n");
385
386 return ret;
387 }
388
pic32_spi_set_word_size(struct pic32_spi * pic32s,u8 bits_per_word)389 static int pic32_spi_set_word_size(struct pic32_spi *pic32s, u8 bits_per_word)
390 {
391 enum dma_slave_buswidth dmawidth;
392 u32 buswidth, v;
393
394 switch (bits_per_word) {
395 case 8:
396 pic32s->rx_fifo = pic32_spi_rx_byte;
397 pic32s->tx_fifo = pic32_spi_tx_byte;
398 buswidth = PIC32_BPW_8;
399 dmawidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
400 break;
401 case 16:
402 pic32s->rx_fifo = pic32_spi_rx_word;
403 pic32s->tx_fifo = pic32_spi_tx_word;
404 buswidth = PIC32_BPW_16;
405 dmawidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
406 break;
407 case 32:
408 pic32s->rx_fifo = pic32_spi_rx_dword;
409 pic32s->tx_fifo = pic32_spi_tx_dword;
410 buswidth = PIC32_BPW_32;
411 dmawidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
412 break;
413 default:
414 /* not supported */
415 return -EINVAL;
416 }
417
418 /* calculate maximum number of words fifos can hold */
419 pic32s->fifo_n_elm = DIV_ROUND_UP(pic32s->fifo_n_byte,
420 bits_per_word / 8);
421 /* set word size */
422 v = readl(&pic32s->regs->ctrl);
423 v &= ~(CTRL_BPW_MASK << CTRL_BPW_SHIFT);
424 v |= buswidth << CTRL_BPW_SHIFT;
425 writel(v, &pic32s->regs->ctrl);
426
427 /* re-configure dma width, if required */
428 if (test_bit(PIC32F_DMA_PREP, &pic32s->flags))
429 pic32_spi_dma_config(pic32s, dmawidth);
430
431 return 0;
432 }
433
pic32_spi_prepare_hardware(struct spi_master * master)434 static int pic32_spi_prepare_hardware(struct spi_master *master)
435 {
436 struct pic32_spi *pic32s = spi_master_get_devdata(master);
437
438 pic32_spi_enable(pic32s);
439
440 return 0;
441 }
442
pic32_spi_prepare_message(struct spi_master * master,struct spi_message * msg)443 static int pic32_spi_prepare_message(struct spi_master *master,
444 struct spi_message *msg)
445 {
446 struct pic32_spi *pic32s = spi_master_get_devdata(master);
447 struct spi_device *spi = msg->spi;
448 u32 val;
449
450 /* set device specific bits_per_word */
451 if (pic32s->bits_per_word != spi->bits_per_word) {
452 pic32_spi_set_word_size(pic32s, spi->bits_per_word);
453 pic32s->bits_per_word = spi->bits_per_word;
454 }
455
456 /* device specific speed change */
457 if (pic32s->speed_hz != spi->max_speed_hz) {
458 pic32_spi_set_clk_rate(pic32s, spi->max_speed_hz);
459 pic32s->speed_hz = spi->max_speed_hz;
460 }
461
462 /* device specific mode change */
463 if (pic32s->mode != spi->mode) {
464 val = readl(&pic32s->regs->ctrl);
465 /* active low */
466 if (spi->mode & SPI_CPOL)
467 val |= CTRL_CKP;
468 else
469 val &= ~CTRL_CKP;
470 /* tx on rising edge */
471 if (spi->mode & SPI_CPHA)
472 val &= ~CTRL_CKE;
473 else
474 val |= CTRL_CKE;
475
476 /* rx at end of tx */
477 val |= CTRL_SMP;
478 writel(val, &pic32s->regs->ctrl);
479 pic32s->mode = spi->mode;
480 }
481
482 return 0;
483 }
484
pic32_spi_can_dma(struct spi_master * master,struct spi_device * spi,struct spi_transfer * xfer)485 static bool pic32_spi_can_dma(struct spi_master *master,
486 struct spi_device *spi,
487 struct spi_transfer *xfer)
488 {
489 struct pic32_spi *pic32s = spi_master_get_devdata(master);
490
491 /* skip using DMA on small size transfer to avoid overhead.*/
492 return (xfer->len >= PIC32_DMA_LEN_MIN) &&
493 test_bit(PIC32F_DMA_PREP, &pic32s->flags);
494 }
495
pic32_spi_one_transfer(struct spi_master * master,struct spi_device * spi,struct spi_transfer * transfer)496 static int pic32_spi_one_transfer(struct spi_master *master,
497 struct spi_device *spi,
498 struct spi_transfer *transfer)
499 {
500 struct pic32_spi *pic32s;
501 bool dma_issued = false;
502 unsigned long timeout;
503 int ret;
504
505 pic32s = spi_master_get_devdata(master);
506
507 /* handle transfer specific word size change */
508 if (transfer->bits_per_word &&
509 (transfer->bits_per_word != pic32s->bits_per_word)) {
510 ret = pic32_spi_set_word_size(pic32s, transfer->bits_per_word);
511 if (ret)
512 return ret;
513 pic32s->bits_per_word = transfer->bits_per_word;
514 }
515
516 /* handle transfer specific speed change */
517 if (transfer->speed_hz && (transfer->speed_hz != pic32s->speed_hz)) {
518 pic32_spi_set_clk_rate(pic32s, transfer->speed_hz);
519 pic32s->speed_hz = transfer->speed_hz;
520 }
521
522 reinit_completion(&pic32s->xfer_done);
523
524 /* transact by DMA mode */
525 if (transfer->rx_sg.nents && transfer->tx_sg.nents) {
526 ret = pic32_spi_dma_transfer(pic32s, transfer);
527 if (ret) {
528 dev_err(&spi->dev, "dma submit error\n");
529 return ret;
530 }
531
532 /* DMA issued */
533 dma_issued = true;
534 } else {
535 /* set current transfer information */
536 pic32s->tx = (const void *)transfer->tx_buf;
537 pic32s->rx = (const void *)transfer->rx_buf;
538 pic32s->tx_end = pic32s->tx + transfer->len;
539 pic32s->rx_end = pic32s->rx + transfer->len;
540 pic32s->len = transfer->len;
541
542 /* transact by interrupt driven PIO */
543 enable_irq(pic32s->fault_irq);
544 enable_irq(pic32s->rx_irq);
545 enable_irq(pic32s->tx_irq);
546 }
547
548 /* wait for completion */
549 timeout = wait_for_completion_timeout(&pic32s->xfer_done, 2 * HZ);
550 if (timeout == 0) {
551 dev_err(&spi->dev, "wait error/timedout\n");
552 if (dma_issued) {
553 dmaengine_terminate_all(master->dma_rx);
554 dmaengine_terminate_all(master->dma_tx);
555 }
556 ret = -ETIMEDOUT;
557 } else {
558 ret = 0;
559 }
560
561 return ret;
562 }
563
pic32_spi_unprepare_message(struct spi_master * master,struct spi_message * msg)564 static int pic32_spi_unprepare_message(struct spi_master *master,
565 struct spi_message *msg)
566 {
567 /* nothing to do */
568 return 0;
569 }
570
pic32_spi_unprepare_hardware(struct spi_master * master)571 static int pic32_spi_unprepare_hardware(struct spi_master *master)
572 {
573 struct pic32_spi *pic32s = spi_master_get_devdata(master);
574
575 pic32_spi_disable(pic32s);
576
577 return 0;
578 }
579
580 /* This may be called multiple times by same spi dev */
pic32_spi_setup(struct spi_device * spi)581 static int pic32_spi_setup(struct spi_device *spi)
582 {
583 if (!spi->max_speed_hz) {
584 dev_err(&spi->dev, "No max speed HZ parameter\n");
585 return -EINVAL;
586 }
587
588 /* PIC32 spi controller can drive /CS during transfer depending
589 * on tx fifo fill-level. /CS will stay asserted as long as TX
590 * fifo is non-empty, else will be deasserted indicating
591 * completion of the ongoing transfer. This might result into
592 * unreliable/erroneous SPI transactions.
593 * To avoid that we will always handle /CS by toggling GPIO.
594 */
595 if (!gpio_is_valid(spi->cs_gpio))
596 return -EINVAL;
597
598 gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
599
600 return 0;
601 }
602
pic32_spi_cleanup(struct spi_device * spi)603 static void pic32_spi_cleanup(struct spi_device *spi)
604 {
605 /* de-activate cs-gpio */
606 gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
607 }
608
pic32_spi_dma_prep(struct pic32_spi * pic32s,struct device * dev)609 static int pic32_spi_dma_prep(struct pic32_spi *pic32s, struct device *dev)
610 {
611 struct spi_master *master = pic32s->master;
612 int ret = 0;
613
614 master->dma_rx = dma_request_chan(dev, "spi-rx");
615 if (IS_ERR(master->dma_rx)) {
616 if (PTR_ERR(master->dma_rx) == -EPROBE_DEFER)
617 ret = -EPROBE_DEFER;
618 else
619 dev_warn(dev, "RX channel not found.\n");
620
621 master->dma_rx = NULL;
622 goto out_err;
623 }
624
625 master->dma_tx = dma_request_chan(dev, "spi-tx");
626 if (IS_ERR(master->dma_tx)) {
627 if (PTR_ERR(master->dma_tx) == -EPROBE_DEFER)
628 ret = -EPROBE_DEFER;
629 else
630 dev_warn(dev, "TX channel not found.\n");
631
632 master->dma_tx = NULL;
633 goto out_err;
634 }
635
636 if (pic32_spi_dma_config(pic32s, DMA_SLAVE_BUSWIDTH_1_BYTE))
637 goto out_err;
638
639 /* DMA chnls allocated and prepared */
640 set_bit(PIC32F_DMA_PREP, &pic32s->flags);
641
642 return 0;
643
644 out_err:
645 if (master->dma_rx) {
646 dma_release_channel(master->dma_rx);
647 master->dma_rx = NULL;
648 }
649
650 if (master->dma_tx) {
651 dma_release_channel(master->dma_tx);
652 master->dma_tx = NULL;
653 }
654
655 return ret;
656 }
657
pic32_spi_dma_unprep(struct pic32_spi * pic32s)658 static void pic32_spi_dma_unprep(struct pic32_spi *pic32s)
659 {
660 if (!test_bit(PIC32F_DMA_PREP, &pic32s->flags))
661 return;
662
663 clear_bit(PIC32F_DMA_PREP, &pic32s->flags);
664 if (pic32s->master->dma_rx)
665 dma_release_channel(pic32s->master->dma_rx);
666
667 if (pic32s->master->dma_tx)
668 dma_release_channel(pic32s->master->dma_tx);
669 }
670
pic32_spi_hw_init(struct pic32_spi * pic32s)671 static void pic32_spi_hw_init(struct pic32_spi *pic32s)
672 {
673 u32 ctrl;
674
675 /* disable hardware */
676 pic32_spi_disable(pic32s);
677
678 ctrl = readl(&pic32s->regs->ctrl);
679 /* enable enhanced fifo of 128bit deep */
680 ctrl |= CTRL_ENHBUF;
681 pic32s->fifo_n_byte = 16;
682
683 /* disable framing mode */
684 ctrl &= ~CTRL_FRMEN;
685
686 /* enable master mode while disabled */
687 ctrl |= CTRL_MSTEN;
688
689 /* set tx fifo threshold interrupt */
690 ctrl &= ~(0x3 << CTRL_TX_INT_SHIFT);
691 ctrl |= (TX_FIFO_HALF_EMPTY << CTRL_TX_INT_SHIFT);
692
693 /* set rx fifo threshold interrupt */
694 ctrl &= ~(0x3 << CTRL_RX_INT_SHIFT);
695 ctrl |= (RX_FIFO_NOT_EMPTY << CTRL_RX_INT_SHIFT);
696
697 /* select clk source */
698 ctrl &= ~CTRL_MCLKSEL;
699
700 /* set manual /CS mode */
701 ctrl &= ~CTRL_MSSEN;
702
703 writel(ctrl, &pic32s->regs->ctrl);
704
705 /* enable error reporting */
706 ctrl = CTRL2_TX_UR_EN | CTRL2_RX_OV_EN | CTRL2_FRM_ERR_EN;
707 writel(ctrl, &pic32s->regs->ctrl2_set);
708 }
709
pic32_spi_hw_probe(struct platform_device * pdev,struct pic32_spi * pic32s)710 static int pic32_spi_hw_probe(struct platform_device *pdev,
711 struct pic32_spi *pic32s)
712 {
713 struct resource *mem;
714 int ret;
715
716 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
717 pic32s->regs = devm_ioremap_resource(&pdev->dev, mem);
718 if (IS_ERR(pic32s->regs))
719 return PTR_ERR(pic32s->regs);
720
721 pic32s->dma_base = mem->start;
722
723 /* get irq resources: err-irq, rx-irq, tx-irq */
724 pic32s->fault_irq = platform_get_irq_byname(pdev, "fault");
725 if (pic32s->fault_irq < 0)
726 return pic32s->fault_irq;
727
728 pic32s->rx_irq = platform_get_irq_byname(pdev, "rx");
729 if (pic32s->rx_irq < 0)
730 return pic32s->rx_irq;
731
732 pic32s->tx_irq = platform_get_irq_byname(pdev, "tx");
733 if (pic32s->tx_irq < 0)
734 return pic32s->tx_irq;
735
736 /* get clock */
737 pic32s->clk = devm_clk_get(&pdev->dev, "mck0");
738 if (IS_ERR(pic32s->clk)) {
739 dev_err(&pdev->dev, "clk not found\n");
740 ret = PTR_ERR(pic32s->clk);
741 goto err_unmap_mem;
742 }
743
744 ret = clk_prepare_enable(pic32s->clk);
745 if (ret)
746 goto err_unmap_mem;
747
748 pic32_spi_hw_init(pic32s);
749
750 return 0;
751
752 err_unmap_mem:
753 dev_err(&pdev->dev, "%s failed, err %d\n", __func__, ret);
754 return ret;
755 }
756
pic32_spi_probe(struct platform_device * pdev)757 static int pic32_spi_probe(struct platform_device *pdev)
758 {
759 struct spi_master *master;
760 struct pic32_spi *pic32s;
761 int ret;
762
763 master = spi_alloc_master(&pdev->dev, sizeof(*pic32s));
764 if (!master)
765 return -ENOMEM;
766
767 pic32s = spi_master_get_devdata(master);
768 pic32s->master = master;
769
770 ret = pic32_spi_hw_probe(pdev, pic32s);
771 if (ret)
772 goto err_master;
773
774 master->dev.of_node = pdev->dev.of_node;
775 master->mode_bits = SPI_MODE_3 | SPI_MODE_0 | SPI_CS_HIGH;
776 master->num_chipselect = 1; /* single chip-select */
777 master->max_speed_hz = clk_get_rate(pic32s->clk);
778 master->setup = pic32_spi_setup;
779 master->cleanup = pic32_spi_cleanup;
780 master->flags = SPI_MASTER_MUST_TX | SPI_MASTER_MUST_RX;
781 master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16) |
782 SPI_BPW_MASK(32);
783 master->transfer_one = pic32_spi_one_transfer;
784 master->prepare_message = pic32_spi_prepare_message;
785 master->unprepare_message = pic32_spi_unprepare_message;
786 master->prepare_transfer_hardware = pic32_spi_prepare_hardware;
787 master->unprepare_transfer_hardware = pic32_spi_unprepare_hardware;
788
789 /* optional DMA support */
790 ret = pic32_spi_dma_prep(pic32s, &pdev->dev);
791 if (ret)
792 goto err_bailout;
793
794 if (test_bit(PIC32F_DMA_PREP, &pic32s->flags))
795 master->can_dma = pic32_spi_can_dma;
796
797 init_completion(&pic32s->xfer_done);
798 pic32s->mode = -1;
799
800 /* install irq handlers (with irq-disabled) */
801 irq_set_status_flags(pic32s->fault_irq, IRQ_NOAUTOEN);
802 ret = devm_request_irq(&pdev->dev, pic32s->fault_irq,
803 pic32_spi_fault_irq, IRQF_NO_THREAD,
804 dev_name(&pdev->dev), pic32s);
805 if (ret < 0) {
806 dev_err(&pdev->dev, "request fault-irq %d\n", pic32s->rx_irq);
807 goto err_bailout;
808 }
809
810 /* receive interrupt handler */
811 irq_set_status_flags(pic32s->rx_irq, IRQ_NOAUTOEN);
812 ret = devm_request_irq(&pdev->dev, pic32s->rx_irq,
813 pic32_spi_rx_irq, IRQF_NO_THREAD,
814 dev_name(&pdev->dev), pic32s);
815 if (ret < 0) {
816 dev_err(&pdev->dev, "request rx-irq %d\n", pic32s->rx_irq);
817 goto err_bailout;
818 }
819
820 /* transmit interrupt handler */
821 irq_set_status_flags(pic32s->tx_irq, IRQ_NOAUTOEN);
822 ret = devm_request_irq(&pdev->dev, pic32s->tx_irq,
823 pic32_spi_tx_irq, IRQF_NO_THREAD,
824 dev_name(&pdev->dev), pic32s);
825 if (ret < 0) {
826 dev_err(&pdev->dev, "request tx-irq %d\n", pic32s->tx_irq);
827 goto err_bailout;
828 }
829
830 /* register master */
831 ret = devm_spi_register_master(&pdev->dev, master);
832 if (ret) {
833 dev_err(&master->dev, "failed registering spi master\n");
834 goto err_bailout;
835 }
836
837 platform_set_drvdata(pdev, pic32s);
838
839 return 0;
840
841 err_bailout:
842 pic32_spi_dma_unprep(pic32s);
843 clk_disable_unprepare(pic32s->clk);
844 err_master:
845 spi_master_put(master);
846 return ret;
847 }
848
pic32_spi_remove(struct platform_device * pdev)849 static int pic32_spi_remove(struct platform_device *pdev)
850 {
851 struct pic32_spi *pic32s;
852
853 pic32s = platform_get_drvdata(pdev);
854 pic32_spi_disable(pic32s);
855 clk_disable_unprepare(pic32s->clk);
856 pic32_spi_dma_unprep(pic32s);
857
858 return 0;
859 }
860
861 static const struct of_device_id pic32_spi_of_match[] = {
862 {.compatible = "microchip,pic32mzda-spi",},
863 {},
864 };
865 MODULE_DEVICE_TABLE(of, pic32_spi_of_match);
866
867 static struct platform_driver pic32_spi_driver = {
868 .driver = {
869 .name = "spi-pic32",
870 .of_match_table = of_match_ptr(pic32_spi_of_match),
871 },
872 .probe = pic32_spi_probe,
873 .remove = pic32_spi_remove,
874 };
875
876 module_platform_driver(pic32_spi_driver);
877
878 MODULE_AUTHOR("Purna Chandra Mandal <purna.mandal@microchip.com>");
879 MODULE_DESCRIPTION("Microchip SPI driver for PIC32 SPI controller.");
880 MODULE_LICENSE("GPL v2");
881