1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Designware SPI core controller driver (refer pxa2xx_spi.c)
4 *
5 * Copyright (c) 2009, Intel Corporation.
6 */
7
8 #include <linux/dma-mapping.h>
9 #include <linux/interrupt.h>
10 #include <linux/module.h>
11 #include <linux/preempt.h>
12 #include <linux/highmem.h>
13 #include <linux/delay.h>
14 #include <linux/slab.h>
15 #include <linux/spi/spi.h>
16 #include <linux/spi/spi-mem.h>
17 #include <linux/string.h>
18 #include <linux/of.h>
19
20 #include "spi-dw.h"
21
22 #ifdef CONFIG_DEBUG_FS
23 #include <linux/debugfs.h>
24 #endif
25
26 /* Slave spi_device related */
27 struct chip_data {
28 u32 cr0;
29 u32 rx_sample_dly; /* RX sample delay */
30 };
31
32 #ifdef CONFIG_DEBUG_FS
33
34 #define DW_SPI_DBGFS_REG(_name, _off) \
35 { \
36 .name = _name, \
37 .offset = _off, \
38 }
39
40 static const struct debugfs_reg32 dw_spi_dbgfs_regs[] = {
41 DW_SPI_DBGFS_REG("CTRLR0", DW_SPI_CTRLR0),
42 DW_SPI_DBGFS_REG("CTRLR1", DW_SPI_CTRLR1),
43 DW_SPI_DBGFS_REG("SSIENR", DW_SPI_SSIENR),
44 DW_SPI_DBGFS_REG("SER", DW_SPI_SER),
45 DW_SPI_DBGFS_REG("BAUDR", DW_SPI_BAUDR),
46 DW_SPI_DBGFS_REG("TXFTLR", DW_SPI_TXFTLR),
47 DW_SPI_DBGFS_REG("RXFTLR", DW_SPI_RXFTLR),
48 DW_SPI_DBGFS_REG("TXFLR", DW_SPI_TXFLR),
49 DW_SPI_DBGFS_REG("RXFLR", DW_SPI_RXFLR),
50 DW_SPI_DBGFS_REG("SR", DW_SPI_SR),
51 DW_SPI_DBGFS_REG("IMR", DW_SPI_IMR),
52 DW_SPI_DBGFS_REG("ISR", DW_SPI_ISR),
53 DW_SPI_DBGFS_REG("DMACR", DW_SPI_DMACR),
54 DW_SPI_DBGFS_REG("DMATDLR", DW_SPI_DMATDLR),
55 DW_SPI_DBGFS_REG("DMARDLR", DW_SPI_DMARDLR),
56 DW_SPI_DBGFS_REG("RX_SAMPLE_DLY", DW_SPI_RX_SAMPLE_DLY),
57 };
58
dw_spi_debugfs_init(struct dw_spi * dws)59 static int dw_spi_debugfs_init(struct dw_spi *dws)
60 {
61 char name[32];
62
63 snprintf(name, 32, "dw_spi%d", dws->master->bus_num);
64 dws->debugfs = debugfs_create_dir(name, NULL);
65 if (!dws->debugfs)
66 return -ENOMEM;
67
68 dws->regset.regs = dw_spi_dbgfs_regs;
69 dws->regset.nregs = ARRAY_SIZE(dw_spi_dbgfs_regs);
70 dws->regset.base = dws->regs;
71 debugfs_create_regset32("registers", 0400, dws->debugfs, &dws->regset);
72
73 return 0;
74 }
75
dw_spi_debugfs_remove(struct dw_spi * dws)76 static void dw_spi_debugfs_remove(struct dw_spi *dws)
77 {
78 debugfs_remove_recursive(dws->debugfs);
79 }
80
81 #else
dw_spi_debugfs_init(struct dw_spi * dws)82 static inline int dw_spi_debugfs_init(struct dw_spi *dws)
83 {
84 return 0;
85 }
86
dw_spi_debugfs_remove(struct dw_spi * dws)87 static inline void dw_spi_debugfs_remove(struct dw_spi *dws)
88 {
89 }
90 #endif /* CONFIG_DEBUG_FS */
91
dw_spi_set_cs(struct spi_device * spi,bool enable)92 void dw_spi_set_cs(struct spi_device *spi, bool enable)
93 {
94 struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
95 bool cs_high = !!(spi->mode & SPI_CS_HIGH);
96
97 /*
98 * DW SPI controller demands any native CS being set in order to
99 * proceed with data transfer. So in order to activate the SPI
100 * communications we must set a corresponding bit in the Slave
101 * Enable register no matter whether the SPI core is configured to
102 * support active-high or active-low CS level.
103 */
104 if (cs_high == enable)
105 dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
106 else
107 dw_writel(dws, DW_SPI_SER, 0);
108 }
109 EXPORT_SYMBOL_GPL(dw_spi_set_cs);
110
111 /* Return the max entries we can fill into tx fifo */
tx_max(struct dw_spi * dws)112 static inline u32 tx_max(struct dw_spi *dws)
113 {
114 u32 tx_room, rxtx_gap;
115
116 tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);
117
118 /*
119 * Another concern is about the tx/rx mismatch, we
120 * though to use (dws->fifo_len - rxflr - txflr) as
121 * one maximum value for tx, but it doesn't cover the
122 * data which is out of tx/rx fifo and inside the
123 * shift registers. So a control from sw point of
124 * view is taken.
125 */
126 rxtx_gap = dws->fifo_len - (dws->rx_len - dws->tx_len);
127
128 return min3((u32)dws->tx_len, tx_room, rxtx_gap);
129 }
130
131 /* Return the max entries we should read out of rx fifo */
rx_max(struct dw_spi * dws)132 static inline u32 rx_max(struct dw_spi *dws)
133 {
134 return min_t(u32, dws->rx_len, dw_readl(dws, DW_SPI_RXFLR));
135 }
136
dw_writer(struct dw_spi * dws)137 static void dw_writer(struct dw_spi *dws)
138 {
139 u32 max = tx_max(dws);
140 u32 txw = 0;
141
142 while (max--) {
143 if (dws->tx) {
144 if (dws->n_bytes == 1)
145 txw = *(u8 *)(dws->tx);
146 else if (dws->n_bytes == 2)
147 txw = *(u16 *)(dws->tx);
148 else
149 txw = *(u32 *)(dws->tx);
150
151 dws->tx += dws->n_bytes;
152 }
153 dw_write_io_reg(dws, DW_SPI_DR, txw);
154 --dws->tx_len;
155 }
156 }
157
dw_reader(struct dw_spi * dws)158 static void dw_reader(struct dw_spi *dws)
159 {
160 u32 max = rx_max(dws);
161 u32 rxw;
162
163 while (max--) {
164 rxw = dw_read_io_reg(dws, DW_SPI_DR);
165 if (dws->rx) {
166 if (dws->n_bytes == 1)
167 *(u8 *)(dws->rx) = rxw;
168 else if (dws->n_bytes == 2)
169 *(u16 *)(dws->rx) = rxw;
170 else
171 *(u32 *)(dws->rx) = rxw;
172
173 dws->rx += dws->n_bytes;
174 }
175 --dws->rx_len;
176 }
177 }
178
dw_spi_check_status(struct dw_spi * dws,bool raw)179 int dw_spi_check_status(struct dw_spi *dws, bool raw)
180 {
181 u32 irq_status;
182 int ret = 0;
183
184 if (raw)
185 irq_status = dw_readl(dws, DW_SPI_RISR);
186 else
187 irq_status = dw_readl(dws, DW_SPI_ISR);
188
189 if (irq_status & SPI_INT_RXOI) {
190 dev_err(&dws->master->dev, "RX FIFO overflow detected\n");
191 ret = -EIO;
192 }
193
194 if (irq_status & SPI_INT_RXUI) {
195 dev_err(&dws->master->dev, "RX FIFO underflow detected\n");
196 ret = -EIO;
197 }
198
199 if (irq_status & SPI_INT_TXOI) {
200 dev_err(&dws->master->dev, "TX FIFO overflow detected\n");
201 ret = -EIO;
202 }
203
204 /* Generically handle the erroneous situation */
205 if (ret) {
206 spi_reset_chip(dws);
207 if (dws->master->cur_msg)
208 dws->master->cur_msg->status = ret;
209 }
210
211 return ret;
212 }
213 EXPORT_SYMBOL_GPL(dw_spi_check_status);
214
dw_spi_transfer_handler(struct dw_spi * dws)215 static irqreturn_t dw_spi_transfer_handler(struct dw_spi *dws)
216 {
217 u16 irq_status = dw_readl(dws, DW_SPI_ISR);
218
219 if (dw_spi_check_status(dws, false)) {
220 spi_finalize_current_transfer(dws->master);
221 return IRQ_HANDLED;
222 }
223
224 /*
225 * Read data from the Rx FIFO every time we've got a chance executing
226 * this method. If there is nothing left to receive, terminate the
227 * procedure. Otherwise adjust the Rx FIFO Threshold level if it's a
228 * final stage of the transfer. By doing so we'll get the next IRQ
229 * right when the leftover incoming data is received.
230 */
231 dw_reader(dws);
232 if (!dws->rx_len) {
233 spi_mask_intr(dws, 0xff);
234 spi_finalize_current_transfer(dws->master);
235 } else if (dws->rx_len <= dw_readl(dws, DW_SPI_RXFTLR)) {
236 dw_writel(dws, DW_SPI_RXFTLR, dws->rx_len - 1);
237 }
238
239 /*
240 * Send data out if Tx FIFO Empty IRQ is received. The IRQ will be
241 * disabled after the data transmission is finished so not to
242 * have the TXE IRQ flood at the final stage of the transfer.
243 */
244 if (irq_status & SPI_INT_TXEI) {
245 dw_writer(dws);
246 if (!dws->tx_len)
247 spi_mask_intr(dws, SPI_INT_TXEI);
248 }
249
250 return IRQ_HANDLED;
251 }
252
dw_spi_irq(int irq,void * dev_id)253 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
254 {
255 struct spi_controller *master = dev_id;
256 struct dw_spi *dws = spi_controller_get_devdata(master);
257 u16 irq_status = dw_readl(dws, DW_SPI_ISR) & 0x3f;
258
259 if (!irq_status)
260 return IRQ_NONE;
261
262 if (!master->cur_msg) {
263 spi_mask_intr(dws, 0xff);
264 return IRQ_HANDLED;
265 }
266
267 return dws->transfer_handler(dws);
268 }
269
dw_spi_prepare_cr0(struct dw_spi * dws,struct spi_device * spi)270 static u32 dw_spi_prepare_cr0(struct dw_spi *dws, struct spi_device *spi)
271 {
272 u32 cr0 = 0;
273
274 if (!(dws->caps & DW_SPI_CAP_DWC_SSI)) {
275 /* CTRLR0[ 5: 4] Frame Format */
276 cr0 |= SSI_MOTO_SPI << SPI_FRF_OFFSET;
277
278 /*
279 * SPI mode (SCPOL|SCPH)
280 * CTRLR0[ 6] Serial Clock Phase
281 * CTRLR0[ 7] Serial Clock Polarity
282 */
283 cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << SPI_SCOL_OFFSET;
284 cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << SPI_SCPH_OFFSET;
285
286 /* CTRLR0[11] Shift Register Loop */
287 cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << SPI_SRL_OFFSET;
288 } else {
289 /* CTRLR0[ 7: 6] Frame Format */
290 cr0 |= SSI_MOTO_SPI << DWC_SSI_CTRLR0_FRF_OFFSET;
291
292 /*
293 * SPI mode (SCPOL|SCPH)
294 * CTRLR0[ 8] Serial Clock Phase
295 * CTRLR0[ 9] Serial Clock Polarity
296 */
297 cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << DWC_SSI_CTRLR0_SCPOL_OFFSET;
298 cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << DWC_SSI_CTRLR0_SCPH_OFFSET;
299
300 /* CTRLR0[13] Shift Register Loop */
301 cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << DWC_SSI_CTRLR0_SRL_OFFSET;
302
303 if (dws->caps & DW_SPI_CAP_KEEMBAY_MST)
304 cr0 |= DWC_SSI_CTRLR0_KEEMBAY_MST;
305 }
306
307 return cr0;
308 }
309
dw_spi_update_config(struct dw_spi * dws,struct spi_device * spi,struct dw_spi_cfg * cfg)310 void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
311 struct dw_spi_cfg *cfg)
312 {
313 struct chip_data *chip = spi_get_ctldata(spi);
314 u32 cr0 = chip->cr0;
315 u32 speed_hz;
316 u16 clk_div;
317
318 /* CTRLR0[ 4/3: 0] or CTRLR0[ 20: 16] Data Frame Size */
319 cr0 |= (cfg->dfs - 1) << dws->dfs_offset;
320
321 if (!(dws->caps & DW_SPI_CAP_DWC_SSI))
322 /* CTRLR0[ 9:8] Transfer Mode */
323 cr0 |= cfg->tmode << SPI_TMOD_OFFSET;
324 else
325 /* CTRLR0[11:10] Transfer Mode */
326 cr0 |= cfg->tmode << DWC_SSI_CTRLR0_TMOD_OFFSET;
327
328 dw_writel(dws, DW_SPI_CTRLR0, cr0);
329
330 if (cfg->tmode == SPI_TMOD_EPROMREAD || cfg->tmode == SPI_TMOD_RO)
331 dw_writel(dws, DW_SPI_CTRLR1, cfg->ndf ? cfg->ndf - 1 : 0);
332
333 /* Note DW APB SSI clock divider doesn't support odd numbers */
334 clk_div = (DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1) & 0xfffe;
335 speed_hz = dws->max_freq / clk_div;
336
337 if (dws->current_freq != speed_hz) {
338 spi_set_clk(dws, clk_div);
339 dws->current_freq = speed_hz;
340 }
341
342 /* Update RX sample delay if required */
343 if (dws->cur_rx_sample_dly != chip->rx_sample_dly) {
344 dw_writel(dws, DW_SPI_RX_SAMPLE_DLY, chip->rx_sample_dly);
345 dws->cur_rx_sample_dly = chip->rx_sample_dly;
346 }
347 }
348 EXPORT_SYMBOL_GPL(dw_spi_update_config);
349
dw_spi_irq_setup(struct dw_spi * dws)350 static void dw_spi_irq_setup(struct dw_spi *dws)
351 {
352 u16 level;
353 u8 imask;
354
355 /*
356 * Originally Tx and Rx data lengths match. Rx FIFO Threshold level
357 * will be adjusted at the final stage of the IRQ-based SPI transfer
358 * execution so not to lose the leftover of the incoming data.
359 */
360 level = min_t(u16, dws->fifo_len / 2, dws->tx_len);
361 dw_writel(dws, DW_SPI_TXFTLR, level);
362 dw_writel(dws, DW_SPI_RXFTLR, level - 1);
363
364 dws->transfer_handler = dw_spi_transfer_handler;
365
366 imask = SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI |
367 SPI_INT_RXFI;
368 spi_umask_intr(dws, imask);
369 }
370
371 /*
372 * The iterative procedure of the poll-based transfer is simple: write as much
373 * as possible to the Tx FIFO, wait until the pending to receive data is ready
374 * to be read, read it from the Rx FIFO and check whether the performed
375 * procedure has been successful.
376 *
377 * Note this method the same way as the IRQ-based transfer won't work well for
378 * the SPI devices connected to the controller with native CS due to the
379 * automatic CS assertion/de-assertion.
380 */
dw_spi_poll_transfer(struct dw_spi * dws,struct spi_transfer * transfer)381 static int dw_spi_poll_transfer(struct dw_spi *dws,
382 struct spi_transfer *transfer)
383 {
384 struct spi_delay delay;
385 u16 nbits;
386 int ret;
387
388 delay.unit = SPI_DELAY_UNIT_SCK;
389 nbits = dws->n_bytes * BITS_PER_BYTE;
390
391 do {
392 dw_writer(dws);
393
394 delay.value = nbits * (dws->rx_len - dws->tx_len);
395 spi_delay_exec(&delay, transfer);
396
397 dw_reader(dws);
398
399 ret = dw_spi_check_status(dws, true);
400 if (ret)
401 return ret;
402 } while (dws->rx_len);
403
404 return 0;
405 }
406
dw_spi_transfer_one(struct spi_controller * master,struct spi_device * spi,struct spi_transfer * transfer)407 static int dw_spi_transfer_one(struct spi_controller *master,
408 struct spi_device *spi, struct spi_transfer *transfer)
409 {
410 struct dw_spi *dws = spi_controller_get_devdata(master);
411 struct dw_spi_cfg cfg = {
412 .tmode = SPI_TMOD_TR,
413 .dfs = transfer->bits_per_word,
414 .freq = transfer->speed_hz,
415 };
416 int ret;
417
418 dws->dma_mapped = 0;
419 dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
420 dws->tx = (void *)transfer->tx_buf;
421 dws->tx_len = transfer->len / dws->n_bytes;
422 dws->rx = transfer->rx_buf;
423 dws->rx_len = dws->tx_len;
424
425 /* Ensure the data above is visible for all CPUs */
426 smp_mb();
427
428 spi_enable_chip(dws, 0);
429
430 dw_spi_update_config(dws, spi, &cfg);
431
432 transfer->effective_speed_hz = dws->current_freq;
433
434 /* Check if current transfer is a DMA transaction */
435 if (master->can_dma && master->can_dma(master, spi, transfer))
436 dws->dma_mapped = master->cur_msg_mapped;
437
438 /* For poll mode just disable all interrupts */
439 spi_mask_intr(dws, 0xff);
440
441 if (dws->dma_mapped) {
442 ret = dws->dma_ops->dma_setup(dws, transfer);
443 if (ret)
444 return ret;
445 }
446
447 spi_enable_chip(dws, 1);
448
449 if (dws->dma_mapped)
450 return dws->dma_ops->dma_transfer(dws, transfer);
451 else if (dws->irq == IRQ_NOTCONNECTED)
452 return dw_spi_poll_transfer(dws, transfer);
453
454 dw_spi_irq_setup(dws);
455
456 return 1;
457 }
458
dw_spi_handle_err(struct spi_controller * master,struct spi_message * msg)459 static void dw_spi_handle_err(struct spi_controller *master,
460 struct spi_message *msg)
461 {
462 struct dw_spi *dws = spi_controller_get_devdata(master);
463
464 if (dws->dma_mapped)
465 dws->dma_ops->dma_stop(dws);
466
467 spi_reset_chip(dws);
468 }
469
dw_spi_adjust_mem_op_size(struct spi_mem * mem,struct spi_mem_op * op)470 static int dw_spi_adjust_mem_op_size(struct spi_mem *mem, struct spi_mem_op *op)
471 {
472 if (op->data.dir == SPI_MEM_DATA_IN)
473 op->data.nbytes = clamp_val(op->data.nbytes, 0, SPI_NDF_MASK + 1);
474
475 return 0;
476 }
477
dw_spi_supports_mem_op(struct spi_mem * mem,const struct spi_mem_op * op)478 static bool dw_spi_supports_mem_op(struct spi_mem *mem,
479 const struct spi_mem_op *op)
480 {
481 if (op->data.buswidth > 1 || op->addr.buswidth > 1 ||
482 op->dummy.buswidth > 1 || op->cmd.buswidth > 1)
483 return false;
484
485 return spi_mem_default_supports_op(mem, op);
486 }
487
dw_spi_init_mem_buf(struct dw_spi * dws,const struct spi_mem_op * op)488 static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
489 {
490 unsigned int i, j, len;
491 u8 *out;
492
493 /*
494 * Calculate the total length of the EEPROM command transfer and
495 * either use the pre-allocated buffer or create a temporary one.
496 */
497 len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
498 if (op->data.dir == SPI_MEM_DATA_OUT)
499 len += op->data.nbytes;
500
501 if (len <= SPI_BUF_SIZE) {
502 out = dws->buf;
503 } else {
504 out = kzalloc(len, GFP_KERNEL);
505 if (!out)
506 return -ENOMEM;
507 }
508
509 /*
510 * Collect the operation code, address and dummy bytes into the single
511 * buffer. If it's a transfer with data to be sent, also copy it into the
512 * single buffer in order to speed the data transmission up.
513 */
514 for (i = 0; i < op->cmd.nbytes; ++i)
515 out[i] = SPI_GET_BYTE(op->cmd.opcode, op->cmd.nbytes - i - 1);
516 for (j = 0; j < op->addr.nbytes; ++i, ++j)
517 out[i] = SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j - 1);
518 for (j = 0; j < op->dummy.nbytes; ++i, ++j)
519 out[i] = 0x0;
520
521 if (op->data.dir == SPI_MEM_DATA_OUT)
522 memcpy(&out[i], op->data.buf.out, op->data.nbytes);
523
524 dws->n_bytes = 1;
525 dws->tx = out;
526 dws->tx_len = len;
527 if (op->data.dir == SPI_MEM_DATA_IN) {
528 dws->rx = op->data.buf.in;
529 dws->rx_len = op->data.nbytes;
530 } else {
531 dws->rx = NULL;
532 dws->rx_len = 0;
533 }
534
535 return 0;
536 }
537
dw_spi_free_mem_buf(struct dw_spi * dws)538 static void dw_spi_free_mem_buf(struct dw_spi *dws)
539 {
540 if (dws->tx != dws->buf)
541 kfree(dws->tx);
542 }
543
dw_spi_write_then_read(struct dw_spi * dws,struct spi_device * spi)544 static int dw_spi_write_then_read(struct dw_spi *dws, struct spi_device *spi)
545 {
546 u32 room, entries, sts;
547 unsigned int len;
548 u8 *buf;
549
550 /*
551 * At initial stage we just pre-fill the Tx FIFO in with no rush,
552 * since native CS hasn't been enabled yet and the automatic data
553 * transmission won't start til we do that.
554 */
555 len = min(dws->fifo_len, dws->tx_len);
556 buf = dws->tx;
557 while (len--)
558 dw_write_io_reg(dws, DW_SPI_DR, *buf++);
559
560 /*
561 * After setting any bit in the SER register the transmission will
562 * start automatically. We have to keep up with that procedure
563 * otherwise the CS de-assertion will happen whereupon the memory
564 * operation will be pre-terminated.
565 */
566 len = dws->tx_len - ((void *)buf - dws->tx);
567 dw_spi_set_cs(spi, false);
568 while (len) {
569 entries = readl_relaxed(dws->regs + DW_SPI_TXFLR);
570 if (!entries) {
571 dev_err(&dws->master->dev, "CS de-assertion on Tx\n");
572 return -EIO;
573 }
574 room = min(dws->fifo_len - entries, len);
575 for (; room; --room, --len)
576 dw_write_io_reg(dws, DW_SPI_DR, *buf++);
577 }
578
579 /*
580 * Data fetching will start automatically if the EEPROM-read mode is
581 * activated. We have to keep up with the incoming data pace to
582 * prevent the Rx FIFO overflow causing the inbound data loss.
583 */
584 len = dws->rx_len;
585 buf = dws->rx;
586 while (len) {
587 entries = readl_relaxed(dws->regs + DW_SPI_RXFLR);
588 if (!entries) {
589 sts = readl_relaxed(dws->regs + DW_SPI_RISR);
590 if (sts & SPI_INT_RXOI) {
591 dev_err(&dws->master->dev, "FIFO overflow on Rx\n");
592 return -EIO;
593 }
594 continue;
595 }
596 entries = min(entries, len);
597 for (; entries; --entries, --len)
598 *buf++ = dw_read_io_reg(dws, DW_SPI_DR);
599 }
600
601 return 0;
602 }
603
dw_spi_ctlr_busy(struct dw_spi * dws)604 static inline bool dw_spi_ctlr_busy(struct dw_spi *dws)
605 {
606 return dw_readl(dws, DW_SPI_SR) & SR_BUSY;
607 }
608
dw_spi_wait_mem_op_done(struct dw_spi * dws)609 static int dw_spi_wait_mem_op_done(struct dw_spi *dws)
610 {
611 int retry = SPI_WAIT_RETRIES;
612 struct spi_delay delay;
613 unsigned long ns, us;
614 u32 nents;
615
616 nents = dw_readl(dws, DW_SPI_TXFLR);
617 ns = NSEC_PER_SEC / dws->current_freq * nents;
618 ns *= dws->n_bytes * BITS_PER_BYTE;
619 if (ns <= NSEC_PER_USEC) {
620 delay.unit = SPI_DELAY_UNIT_NSECS;
621 delay.value = ns;
622 } else {
623 us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
624 delay.unit = SPI_DELAY_UNIT_USECS;
625 delay.value = clamp_val(us, 0, USHRT_MAX);
626 }
627
628 while (dw_spi_ctlr_busy(dws) && retry--)
629 spi_delay_exec(&delay, NULL);
630
631 if (retry < 0) {
632 dev_err(&dws->master->dev, "Mem op hanged up\n");
633 return -EIO;
634 }
635
636 return 0;
637 }
638
dw_spi_stop_mem_op(struct dw_spi * dws,struct spi_device * spi)639 static void dw_spi_stop_mem_op(struct dw_spi *dws, struct spi_device *spi)
640 {
641 spi_enable_chip(dws, 0);
642 dw_spi_set_cs(spi, true);
643 spi_enable_chip(dws, 1);
644 }
645
646 /*
647 * The SPI memory operation implementation below is the best choice for the
648 * devices, which are selected by the native chip-select lane. It's
649 * specifically developed to workaround the problem with automatic chip-select
650 * lane toggle when there is no data in the Tx FIFO buffer. Luckily the current
651 * SPI-mem core calls exec_op() callback only if the GPIO-based CS is
652 * unavailable.
653 */
dw_spi_exec_mem_op(struct spi_mem * mem,const struct spi_mem_op * op)654 static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
655 {
656 struct dw_spi *dws = spi_controller_get_devdata(mem->spi->controller);
657 struct dw_spi_cfg cfg;
658 unsigned long flags;
659 int ret;
660
661 /*
662 * Collect the outbound data into a single buffer to speed the
663 * transmission up at least on the initial stage.
664 */
665 ret = dw_spi_init_mem_buf(dws, op);
666 if (ret)
667 return ret;
668
669 /*
670 * DW SPI EEPROM-read mode is required only for the SPI memory Data-IN
671 * operation. Transmit-only mode is suitable for the rest of them.
672 */
673 cfg.dfs = 8;
674 cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
675 if (op->data.dir == SPI_MEM_DATA_IN) {
676 cfg.tmode = SPI_TMOD_EPROMREAD;
677 cfg.ndf = op->data.nbytes;
678 } else {
679 cfg.tmode = SPI_TMOD_TO;
680 }
681
682 spi_enable_chip(dws, 0);
683
684 dw_spi_update_config(dws, mem->spi, &cfg);
685
686 spi_mask_intr(dws, 0xff);
687
688 spi_enable_chip(dws, 1);
689
690 /*
691 * DW APB SSI controller has very nasty peculiarities. First originally
692 * (without any vendor-specific modifications) it doesn't provide a
693 * direct way to set and clear the native chip-select signal. Instead
694 * the controller asserts the CS lane if Tx FIFO isn't empty and a
695 * transmission is going on, and automatically de-asserts it back to
696 * the high level if the Tx FIFO doesn't have anything to be pushed
697 * out. Due to that a multi-tasking or heavy IRQs activity might be
698 * fatal, since the transfer procedure preemption may cause the Tx FIFO
699 * getting empty and sudden CS de-assertion, which in the middle of the
700 * transfer will most likely cause the data loss. Secondly the
701 * EEPROM-read or Read-only DW SPI transfer modes imply the incoming
702 * data being automatically pulled in into the Rx FIFO. So if the
703 * driver software is late in fetching the data from the FIFO before
704 * it's overflown, new incoming data will be lost. In order to make
705 * sure the executed memory operations are CS-atomic and to prevent the
706 * Rx FIFO overflow we have to disable the local interrupts so to block
707 * any preemption during the subsequent IO operations.
708 *
709 * Note. At some circumstances disabling IRQs may not help to prevent
710 * the problems described above. The CS de-assertion and Rx FIFO
711 * overflow may still happen due to the relatively slow system bus or
712 * CPU not working fast enough, so the write-then-read algo implemented
713 * here just won't keep up with the SPI bus data transfer. Such
714 * situation is highly platform specific and is supposed to be fixed by
715 * manually restricting the SPI bus frequency using the
716 * dws->max_mem_freq parameter.
717 */
718 local_irq_save(flags);
719 preempt_disable();
720
721 ret = dw_spi_write_then_read(dws, mem->spi);
722
723 local_irq_restore(flags);
724 preempt_enable();
725
726 /*
727 * Wait for the operation being finished and check the controller
728 * status only if there hasn't been any run-time error detected. In the
729 * former case it's just pointless. In the later one to prevent an
730 * additional error message printing since any hw error flag being set
731 * would be due to an error detected on the data transfer.
732 */
733 if (!ret) {
734 ret = dw_spi_wait_mem_op_done(dws);
735 if (!ret)
736 ret = dw_spi_check_status(dws, true);
737 }
738
739 dw_spi_stop_mem_op(dws, mem->spi);
740
741 dw_spi_free_mem_buf(dws);
742
743 return ret;
744 }
745
746 /*
747 * Initialize the default memory operations if a glue layer hasn't specified
748 * custom ones. Direct mapping operations will be preserved anyway since DW SPI
749 * controller doesn't have an embedded dirmap interface. Note the memory
750 * operations implemented in this driver is the best choice only for the DW APB
751 * SSI controller with standard native CS functionality. If a hardware vendor
752 * has fixed the automatic CS assertion/de-assertion peculiarity, then it will
753 * be safer to use the normal SPI-messages-based transfers implementation.
754 */
dw_spi_init_mem_ops(struct dw_spi * dws)755 static void dw_spi_init_mem_ops(struct dw_spi *dws)
756 {
757 if (!dws->mem_ops.exec_op && !(dws->caps & DW_SPI_CAP_CS_OVERRIDE) &&
758 !dws->set_cs) {
759 dws->mem_ops.adjust_op_size = dw_spi_adjust_mem_op_size;
760 dws->mem_ops.supports_op = dw_spi_supports_mem_op;
761 dws->mem_ops.exec_op = dw_spi_exec_mem_op;
762 if (!dws->max_mem_freq)
763 dws->max_mem_freq = dws->max_freq;
764 }
765 }
766
767 /* This may be called twice for each spi dev */
dw_spi_setup(struct spi_device * spi)768 static int dw_spi_setup(struct spi_device *spi)
769 {
770 struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
771 struct chip_data *chip;
772
773 /* Only alloc on first setup */
774 chip = spi_get_ctldata(spi);
775 if (!chip) {
776 struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
777 u32 rx_sample_dly_ns;
778
779 chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
780 if (!chip)
781 return -ENOMEM;
782 spi_set_ctldata(spi, chip);
783 /* Get specific / default rx-sample-delay */
784 if (device_property_read_u32(&spi->dev,
785 "rx-sample-delay-ns",
786 &rx_sample_dly_ns) != 0)
787 /* Use default controller value */
788 rx_sample_dly_ns = dws->def_rx_sample_dly_ns;
789 chip->rx_sample_dly = DIV_ROUND_CLOSEST(rx_sample_dly_ns,
790 NSEC_PER_SEC /
791 dws->max_freq);
792 }
793
794 /*
795 * Update CR0 data each time the setup callback is invoked since
796 * the device parameters could have been changed, for instance, by
797 * the MMC SPI driver or something else.
798 */
799 chip->cr0 = dw_spi_prepare_cr0(dws, spi);
800
801 return 0;
802 }
803
dw_spi_cleanup(struct spi_device * spi)804 static void dw_spi_cleanup(struct spi_device *spi)
805 {
806 struct chip_data *chip = spi_get_ctldata(spi);
807
808 kfree(chip);
809 spi_set_ctldata(spi, NULL);
810 }
811
812 /* Restart the controller, disable all interrupts, clean rx fifo */
spi_hw_init(struct device * dev,struct dw_spi * dws)813 static void spi_hw_init(struct device *dev, struct dw_spi *dws)
814 {
815 spi_reset_chip(dws);
816
817 /*
818 * Try to detect the FIFO depth if not set by interface driver,
819 * the depth could be from 2 to 256 from HW spec
820 */
821 if (!dws->fifo_len) {
822 u32 fifo;
823
824 for (fifo = 1; fifo < 256; fifo++) {
825 dw_writel(dws, DW_SPI_TXFTLR, fifo);
826 if (fifo != dw_readl(dws, DW_SPI_TXFTLR))
827 break;
828 }
829 dw_writel(dws, DW_SPI_TXFTLR, 0);
830
831 dws->fifo_len = (fifo == 1) ? 0 : fifo;
832 dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
833 }
834
835 /*
836 * Detect CTRLR0.DFS field size and offset by testing the lowest bits
837 * writability. Note DWC SSI controller also has the extended DFS, but
838 * with zero offset.
839 */
840 if (!(dws->caps & DW_SPI_CAP_DWC_SSI)) {
841 u32 cr0, tmp = dw_readl(dws, DW_SPI_CTRLR0);
842
843 spi_enable_chip(dws, 0);
844 dw_writel(dws, DW_SPI_CTRLR0, 0xffffffff);
845 cr0 = dw_readl(dws, DW_SPI_CTRLR0);
846 dw_writel(dws, DW_SPI_CTRLR0, tmp);
847 spi_enable_chip(dws, 1);
848
849 if (!(cr0 & SPI_DFS_MASK)) {
850 dws->caps |= DW_SPI_CAP_DFS32;
851 dws->dfs_offset = SPI_DFS32_OFFSET;
852 dev_dbg(dev, "Detected 32-bits max data frame size\n");
853 }
854 } else {
855 dws->caps |= DW_SPI_CAP_DFS32;
856 }
857
858 /* enable HW fixup for explicit CS deselect for Amazon's alpine chip */
859 if (dws->caps & DW_SPI_CAP_CS_OVERRIDE)
860 dw_writel(dws, DW_SPI_CS_OVERRIDE, 0xF);
861 }
862
dw_spi_add_host(struct device * dev,struct dw_spi * dws)863 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
864 {
865 struct spi_controller *master;
866 int ret;
867
868 if (!dws)
869 return -EINVAL;
870
871 master = spi_alloc_master(dev, 0);
872 if (!master)
873 return -ENOMEM;
874
875 dws->master = master;
876 dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
877
878 spi_controller_set_devdata(master, dws);
879
880 /* Basic HW init */
881 spi_hw_init(dev, dws);
882
883 ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
884 master);
885 if (ret < 0 && ret != -ENOTCONN) {
886 dev_err(dev, "can not get IRQ\n");
887 goto err_free_master;
888 }
889
890 dw_spi_init_mem_ops(dws);
891
892 master->use_gpio_descriptors = true;
893 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
894 if (dws->caps & DW_SPI_CAP_DFS32)
895 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
896 else
897 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);
898 master->bus_num = dws->bus_num;
899 master->num_chipselect = dws->num_cs;
900 master->setup = dw_spi_setup;
901 master->cleanup = dw_spi_cleanup;
902 if (dws->set_cs)
903 master->set_cs = dws->set_cs;
904 else
905 master->set_cs = dw_spi_set_cs;
906 master->transfer_one = dw_spi_transfer_one;
907 master->handle_err = dw_spi_handle_err;
908 if (dws->mem_ops.exec_op)
909 master->mem_ops = &dws->mem_ops;
910 master->max_speed_hz = dws->max_freq;
911 master->dev.of_node = dev->of_node;
912 master->dev.fwnode = dev->fwnode;
913 master->flags = SPI_MASTER_GPIO_SS;
914 master->auto_runtime_pm = true;
915
916 /* Get default rx sample delay */
917 device_property_read_u32(dev, "rx-sample-delay-ns",
918 &dws->def_rx_sample_dly_ns);
919
920 if (dws->dma_ops && dws->dma_ops->dma_init) {
921 ret = dws->dma_ops->dma_init(dev, dws);
922 if (ret) {
923 dev_warn(dev, "DMA init failed\n");
924 } else {
925 master->can_dma = dws->dma_ops->can_dma;
926 master->flags |= SPI_CONTROLLER_MUST_TX;
927 }
928 }
929
930 ret = spi_register_controller(master);
931 if (ret) {
932 dev_err(&master->dev, "problem registering spi master\n");
933 goto err_dma_exit;
934 }
935
936 dw_spi_debugfs_init(dws);
937 return 0;
938
939 err_dma_exit:
940 if (dws->dma_ops && dws->dma_ops->dma_exit)
941 dws->dma_ops->dma_exit(dws);
942 spi_enable_chip(dws, 0);
943 free_irq(dws->irq, master);
944 err_free_master:
945 spi_controller_put(master);
946 return ret;
947 }
948 EXPORT_SYMBOL_GPL(dw_spi_add_host);
949
dw_spi_remove_host(struct dw_spi * dws)950 void dw_spi_remove_host(struct dw_spi *dws)
951 {
952 dw_spi_debugfs_remove(dws);
953
954 spi_unregister_controller(dws->master);
955
956 if (dws->dma_ops && dws->dma_ops->dma_exit)
957 dws->dma_ops->dma_exit(dws);
958
959 spi_shutdown_chip(dws);
960
961 free_irq(dws->irq, dws->master);
962 }
963 EXPORT_SYMBOL_GPL(dw_spi_remove_host);
964
dw_spi_suspend_host(struct dw_spi * dws)965 int dw_spi_suspend_host(struct dw_spi *dws)
966 {
967 int ret;
968
969 ret = spi_controller_suspend(dws->master);
970 if (ret)
971 return ret;
972
973 spi_shutdown_chip(dws);
974 return 0;
975 }
976 EXPORT_SYMBOL_GPL(dw_spi_suspend_host);
977
dw_spi_resume_host(struct dw_spi * dws)978 int dw_spi_resume_host(struct dw_spi *dws)
979 {
980 spi_hw_init(&dws->master->dev, dws);
981 return spi_controller_resume(dws->master);
982 }
983 EXPORT_SYMBOL_GPL(dw_spi_resume_host);
984
985 MODULE_AUTHOR("Feng Tang <feng.tang@intel.com>");
986 MODULE_DESCRIPTION("Driver for DesignWare SPI controller core");
987 MODULE_LICENSE("GPL v2");
988