1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Access SD/MMC cards through SPI master controllers
4 *
5 * (C) Copyright 2005, Intec Automation,
6 * Mike Lavender (mike@steroidmicros)
7 * (C) Copyright 2006-2007, David Brownell
8 * (C) Copyright 2007, Axis Communications,
9 * Hans-Peter Nilsson (hp@axis.com)
10 * (C) Copyright 2007, ATRON electronic GmbH,
11 * Jan Nikitenko <jan.nikitenko@gmail.com>
12 */
13#include <linux/sched.h>
14#include <linux/delay.h>
15#include <linux/slab.h>
16#include <linux/module.h>
17#include <linux/bio.h>
18#include <linux/crc7.h>
19#include <linux/crc-itu-t.h>
20#include <linux/scatterlist.h>
21
22#include <linux/mmc/host.h>
23#include <linux/mmc/mmc.h> /* for R1_SPI_* bit values */
24#include <linux/mmc/slot-gpio.h>
25
26#include <linux/spi/spi.h>
27#include <linux/spi/mmc_spi.h>
28
29#include <asm/unaligned.h>
30
31
32/* NOTES:
33 *
34 * - For now, we won't try to interoperate with a real mmc/sd/sdio
35 * controller, although some of them do have hardware support for
36 * SPI protocol. The main reason for such configs would be mmc-ish
37 * cards like DataFlash, which don't support that "native" protocol.
38 *
39 * We don't have a "DataFlash/MMC/SD/SDIO card slot" abstraction to
40 * switch between driver stacks, and in any case if "native" mode
41 * is available, it will be faster and hence preferable.
42 *
43 * - MMC depends on a different chipselect management policy than the
44 * SPI interface currently supports for shared bus segments: it needs
45 * to issue multiple spi_message requests with the chipselect active,
46 * using the results of one message to decide the next one to issue.
47 *
48 * Pending updates to the programming interface, this driver expects
49 * that it not share the bus with other drivers (precluding conflicts).
50 *
51 * - We tell the controller to keep the chipselect active from the
52 * beginning of an mmc_host_ops.request until the end. So beware
53 * of SPI controller drivers that mis-handle the cs_change flag!
54 *
55 * However, many cards seem OK with chipselect flapping up/down
56 * during that time ... at least on unshared bus segments.
57 */
58
59
60/*
61 * Local protocol constants, internal to data block protocols.
62 */
63
64/* Response tokens used to ack each block written: */
65#define SPI_MMC_RESPONSE_CODE(x) ((x) & 0x1f)
66#define SPI_RESPONSE_ACCEPTED ((2 << 1)|1)
67#define SPI_RESPONSE_CRC_ERR ((5 << 1)|1)
68#define SPI_RESPONSE_WRITE_ERR ((6 << 1)|1)
69
70/* Read and write blocks start with these tokens and end with crc;
71 * on error, read tokens act like a subset of R2_SPI_* values.
72 */
73#define SPI_TOKEN_SINGLE 0xfe /* single block r/w, multiblock read */
74#define SPI_TOKEN_MULTI_WRITE 0xfc /* multiblock write */
75#define SPI_TOKEN_STOP_TRAN 0xfd /* terminate multiblock write */
76
77#define MMC_SPI_BLOCKSIZE 512
78
79#define MMC_SPI_R1B_TIMEOUT_MS 3000
80#define MMC_SPI_INIT_TIMEOUT_MS 3000
81
82/* One of the critical speed parameters is the amount of data which may
83 * be transferred in one command. If this value is too low, the SD card
84 * controller has to do multiple partial block writes (argggh!). With
85 * today (2008) SD cards there is little speed gain if we transfer more
86 * than 64 KBytes at a time. So use this value until there is any indication
87 * that we should do more here.
88 */
89#define MMC_SPI_BLOCKSATONCE 128
90
91/****************************************************************************/
92
93/*
94 * Local Data Structures
95 */
96
97/* "scratch" is per-{command,block} data exchanged with the card */
98struct scratch {
99 u8 status[29];
100 u8 data_token;
101 __be16 crc_val;
102};
103
104struct mmc_spi_host {
105 struct mmc_host *mmc;
106 struct spi_device *spi;
107
108 unsigned char power_mode;
109 u16 powerup_msecs;
110
111 struct mmc_spi_platform_data *pdata;
112
113 /* for bulk data transfers */
114 struct spi_transfer token, t, crc, early_status;
115 struct spi_message m;
116
117 /* for status readback */
118 struct spi_transfer status;
119 struct spi_message readback;
120
121 /* buffer used for commands and for message "overhead" */
122 struct scratch *data;
123
124 /* Specs say to write ones most of the time, even when the card
125 * has no need to read its input data; and many cards won't care.
126 * This is our source of those ones.
127 */
128 void *ones;
129};
130
131
132/****************************************************************************/
133
134/*
135 * MMC-over-SPI protocol glue, used by the MMC stack interface
136 */
137
138static inline int mmc_cs_off(struct mmc_spi_host *host)
139{
140 /* chipselect will always be inactive after setup() */
141 return spi_setup(spi: host->spi);
142}
143
144static int mmc_spi_readbytes(struct mmc_spi_host *host, unsigned int len)
145{
146 if (len > sizeof(*host->data)) {
147 WARN_ON(1);
148 return -EIO;
149 }
150
151 host->status.len = len;
152
153 return spi_sync_locked(spi: host->spi, message: &host->readback);
154}
155
156static int mmc_spi_skip(struct mmc_spi_host *host, unsigned long timeout,
157 unsigned n, u8 byte)
158{
159 u8 *cp = host->data->status;
160 unsigned long start = jiffies;
161
162 do {
163 int status;
164 unsigned i;
165
166 status = mmc_spi_readbytes(host, len: n);
167 if (status < 0)
168 return status;
169
170 for (i = 0; i < n; i++) {
171 if (cp[i] != byte)
172 return cp[i];
173 }
174
175 /* If we need long timeouts, we may release the CPU */
176 cond_resched();
177 } while (time_is_after_jiffies(start + timeout));
178 return -ETIMEDOUT;
179}
180
181static inline int
182mmc_spi_wait_unbusy(struct mmc_spi_host *host, unsigned long timeout)
183{
184 return mmc_spi_skip(host, timeout, n: sizeof(host->data->status), byte: 0);
185}
186
187static int mmc_spi_readtoken(struct mmc_spi_host *host, unsigned long timeout)
188{
189 return mmc_spi_skip(host, timeout, n: 1, byte: 0xff);
190}
191
192
193/*
194 * Note that for SPI, cmd->resp[0] is not the same data as "native" protocol
195 * hosts return! The low byte holds R1_SPI bits. The next byte may hold
196 * R2_SPI bits ... for SEND_STATUS, or after data read errors.
197 *
198 * cmd->resp[1] holds any four-byte response, for R3 (READ_OCR) and on
199 * newer cards R7 (IF_COND).
200 */
201
202static char *maptype(struct mmc_command *cmd)
203{
204 switch (mmc_spi_resp_type(cmd)) {
205 case MMC_RSP_SPI_R1: return "R1";
206 case MMC_RSP_SPI_R1B: return "R1B";
207 case MMC_RSP_SPI_R2: return "R2/R5";
208 case MMC_RSP_SPI_R3: return "R3/R4/R7";
209 default: return "?";
210 }
211}
212
213/* return zero, else negative errno after setting cmd->error */
214static int mmc_spi_response_get(struct mmc_spi_host *host,
215 struct mmc_command *cmd, int cs_on)
216{
217 unsigned long timeout_ms;
218 u8 *cp = host->data->status;
219 u8 *end = cp + host->t.len;
220 int value = 0;
221 int bitshift;
222 u8 leftover = 0;
223 unsigned short rotator;
224 int i;
225 char tag[32];
226
227 snprintf(buf: tag, size: sizeof(tag), fmt: " ... CMD%d response SPI_%s",
228 cmd->opcode, maptype(cmd));
229
230 /* Except for data block reads, the whole response will already
231 * be stored in the scratch buffer. It's somewhere after the
232 * command and the first byte we read after it. We ignore that
233 * first byte. After STOP_TRANSMISSION command it may include
234 * two data bits, but otherwise it's all ones.
235 */
236 cp += 8;
237 while (cp < end && *cp == 0xff)
238 cp++;
239
240 /* Data block reads (R1 response types) may need more data... */
241 if (cp == end) {
242 cp = host->data->status;
243 end = cp+1;
244
245 /* Card sends N(CR) (== 1..8) bytes of all-ones then one
246 * status byte ... and we already scanned 2 bytes.
247 *
248 * REVISIT block read paths use nasty byte-at-a-time I/O
249 * so it can always DMA directly into the target buffer.
250 * It'd probably be better to memcpy() the first chunk and
251 * avoid extra i/o calls...
252 *
253 * Note we check for more than 8 bytes, because in practice,
254 * some SD cards are slow...
255 */
256 for (i = 2; i < 16; i++) {
257 value = mmc_spi_readbytes(host, len: 1);
258 if (value < 0)
259 goto done;
260 if (*cp != 0xff)
261 goto checkstatus;
262 }
263 value = -ETIMEDOUT;
264 goto done;
265 }
266
267checkstatus:
268 bitshift = 0;
269 if (*cp & 0x80) {
270 /* Houston, we have an ugly card with a bit-shifted response */
271 rotator = *cp++ << 8;
272 /* read the next byte */
273 if (cp == end) {
274 value = mmc_spi_readbytes(host, len: 1);
275 if (value < 0)
276 goto done;
277 cp = host->data->status;
278 end = cp+1;
279 }
280 rotator |= *cp++;
281 while (rotator & 0x8000) {
282 bitshift++;
283 rotator <<= 1;
284 }
285 cmd->resp[0] = rotator >> 8;
286 leftover = rotator;
287 } else {
288 cmd->resp[0] = *cp++;
289 }
290 cmd->error = 0;
291
292 /* Status byte: the entire seven-bit R1 response. */
293 if (cmd->resp[0] != 0) {
294 if ((R1_SPI_PARAMETER | R1_SPI_ADDRESS)
295 & cmd->resp[0])
296 value = -EFAULT; /* Bad address */
297 else if (R1_SPI_ILLEGAL_COMMAND & cmd->resp[0])
298 value = -ENOSYS; /* Function not implemented */
299 else if (R1_SPI_COM_CRC & cmd->resp[0])
300 value = -EILSEQ; /* Illegal byte sequence */
301 else if ((R1_SPI_ERASE_SEQ | R1_SPI_ERASE_RESET)
302 & cmd->resp[0])
303 value = -EIO; /* I/O error */
304 /* else R1_SPI_IDLE, "it's resetting" */
305 }
306
307 switch (mmc_spi_resp_type(cmd)) {
308
309 /* SPI R1B == R1 + busy; STOP_TRANSMISSION (for multiblock reads)
310 * and less-common stuff like various erase operations.
311 */
312 case MMC_RSP_SPI_R1B:
313 /* maybe we read all the busy tokens already */
314 while (cp < end && *cp == 0)
315 cp++;
316 if (cp == end) {
317 timeout_ms = cmd->busy_timeout ? cmd->busy_timeout :
318 MMC_SPI_R1B_TIMEOUT_MS;
319 mmc_spi_wait_unbusy(host, timeout: msecs_to_jiffies(m: timeout_ms));
320 }
321 break;
322
323 /* SPI R2 == R1 + second status byte; SEND_STATUS
324 * SPI R5 == R1 + data byte; IO_RW_DIRECT
325 */
326 case MMC_RSP_SPI_R2:
327 /* read the next byte */
328 if (cp == end) {
329 value = mmc_spi_readbytes(host, len: 1);
330 if (value < 0)
331 goto done;
332 cp = host->data->status;
333 end = cp+1;
334 }
335 if (bitshift) {
336 rotator = leftover << 8;
337 rotator |= *cp << bitshift;
338 cmd->resp[0] |= (rotator & 0xFF00);
339 } else {
340 cmd->resp[0] |= *cp << 8;
341 }
342 break;
343
344 /* SPI R3, R4, or R7 == R1 + 4 bytes */
345 case MMC_RSP_SPI_R3:
346 rotator = leftover << 8;
347 cmd->resp[1] = 0;
348 for (i = 0; i < 4; i++) {
349 cmd->resp[1] <<= 8;
350 /* read the next byte */
351 if (cp == end) {
352 value = mmc_spi_readbytes(host, len: 1);
353 if (value < 0)
354 goto done;
355 cp = host->data->status;
356 end = cp+1;
357 }
358 if (bitshift) {
359 rotator |= *cp++ << bitshift;
360 cmd->resp[1] |= (rotator >> 8);
361 rotator <<= 8;
362 } else {
363 cmd->resp[1] |= *cp++;
364 }
365 }
366 break;
367
368 /* SPI R1 == just one status byte */
369 case MMC_RSP_SPI_R1:
370 break;
371
372 default:
373 dev_dbg(&host->spi->dev, "bad response type %04x\n",
374 mmc_spi_resp_type(cmd));
375 if (value >= 0)
376 value = -EINVAL;
377 goto done;
378 }
379
380 if (value < 0)
381 dev_dbg(&host->spi->dev, "%s: resp %04x %08x\n",
382 tag, cmd->resp[0], cmd->resp[1]);
383
384 /* disable chipselect on errors and some success cases */
385 if (value >= 0 && cs_on)
386 return value;
387done:
388 if (value < 0)
389 cmd->error = value;
390 mmc_cs_off(host);
391 return value;
392}
393
394/* Issue command and read its response.
395 * Returns zero on success, negative for error.
396 *
397 * On error, caller must cope with mmc core retry mechanism. That
398 * means immediate low-level resubmit, which affects the bus lock...
399 */
400static int
401mmc_spi_command_send(struct mmc_spi_host *host,
402 struct mmc_request *mrq,
403 struct mmc_command *cmd, int cs_on)
404{
405 struct scratch *data = host->data;
406 u8 *cp = data->status;
407 int status;
408 struct spi_transfer *t;
409
410 /* We can handle most commands (except block reads) in one full
411 * duplex I/O operation before either starting the next transfer
412 * (data block or command) or else deselecting the card.
413 *
414 * First, write 7 bytes:
415 * - an all-ones byte to ensure the card is ready
416 * - opcode byte (plus start and transmission bits)
417 * - four bytes of big-endian argument
418 * - crc7 (plus end bit) ... always computed, it's cheap
419 *
420 * We init the whole buffer to all-ones, which is what we need
421 * to write while we're reading (later) response data.
422 */
423 memset(cp, 0xff, sizeof(data->status));
424
425 cp[1] = 0x40 | cmd->opcode;
426 put_unaligned_be32(val: cmd->arg, p: cp + 2);
427 cp[6] = crc7_be(crc: 0, buffer: cp + 1, len: 5) | 0x01;
428 cp += 7;
429
430 /* Then, read up to 13 bytes (while writing all-ones):
431 * - N(CR) (== 1..8) bytes of all-ones
432 * - status byte (for all response types)
433 * - the rest of the response, either:
434 * + nothing, for R1 or R1B responses
435 * + second status byte, for R2 responses
436 * + four data bytes, for R3 and R7 responses
437 *
438 * Finally, read some more bytes ... in the nice cases we know in
439 * advance how many, and reading 1 more is always OK:
440 * - N(EC) (== 0..N) bytes of all-ones, before deselect/finish
441 * - N(RC) (== 1..N) bytes of all-ones, before next command
442 * - N(WR) (== 1..N) bytes of all-ones, before data write
443 *
444 * So in those cases one full duplex I/O of at most 21 bytes will
445 * handle the whole command, leaving the card ready to receive a
446 * data block or new command. We do that whenever we can, shaving
447 * CPU and IRQ costs (especially when using DMA or FIFOs).
448 *
449 * There are two other cases, where it's not generally practical
450 * to rely on a single I/O:
451 *
452 * - R1B responses need at least N(EC) bytes of all-zeroes.
453 *
454 * In this case we can *try* to fit it into one I/O, then
455 * maybe read more data later.
456 *
457 * - Data block reads are more troublesome, since a variable
458 * number of padding bytes precede the token and data.
459 * + N(CX) (== 0..8) bytes of all-ones, before CSD or CID
460 * + N(AC) (== 1..many) bytes of all-ones
461 *
462 * In this case we currently only have minimal speedups here:
463 * when N(CR) == 1 we can avoid I/O in response_get().
464 */
465 if (cs_on && (mrq->data->flags & MMC_DATA_READ)) {
466 cp += 2; /* min(N(CR)) + status */
467 /* R1 */
468 } else {
469 cp += 10; /* max(N(CR)) + status + min(N(RC),N(WR)) */
470 if (cmd->flags & MMC_RSP_SPI_S2) /* R2/R5 */
471 cp++;
472 else if (cmd->flags & MMC_RSP_SPI_B4) /* R3/R4/R7 */
473 cp += 4;
474 else if (cmd->flags & MMC_RSP_BUSY) /* R1B */
475 cp = data->status + sizeof(data->status);
476 /* else: R1 (most commands) */
477 }
478
479 dev_dbg(&host->spi->dev, " CMD%d, resp %s\n",
480 cmd->opcode, maptype(cmd));
481
482 /* send command, leaving chipselect active */
483 spi_message_init(m: &host->m);
484
485 t = &host->t;
486 memset(t, 0, sizeof(*t));
487 t->tx_buf = t->rx_buf = data->status;
488 t->len = cp - data->status;
489 t->cs_change = 1;
490 spi_message_add_tail(t, m: &host->m);
491
492 status = spi_sync_locked(spi: host->spi, message: &host->m);
493 if (status < 0) {
494 dev_dbg(&host->spi->dev, " ... write returned %d\n", status);
495 cmd->error = status;
496 return status;
497 }
498
499 /* after no-data commands and STOP_TRANSMISSION, chipselect off */
500 return mmc_spi_response_get(host, cmd, cs_on);
501}
502
503/* Build data message with up to four separate transfers. For TX, we
504 * start by writing the data token. And in most cases, we finish with
505 * a status transfer.
506 *
507 * We always provide TX data for data and CRC. The MMC/SD protocol
508 * requires us to write ones; but Linux defaults to writing zeroes;
509 * so we explicitly initialize it to all ones on RX paths.
510 */
511static void
512mmc_spi_setup_data_message(struct mmc_spi_host *host, bool multiple, bool write)
513{
514 struct spi_transfer *t;
515 struct scratch *scratch = host->data;
516
517 spi_message_init(m: &host->m);
518
519 /* for reads, readblock() skips 0xff bytes before finding
520 * the token; for writes, this transfer issues that token.
521 */
522 if (write) {
523 t = &host->token;
524 memset(t, 0, sizeof(*t));
525 t->len = 1;
526 if (multiple)
527 scratch->data_token = SPI_TOKEN_MULTI_WRITE;
528 else
529 scratch->data_token = SPI_TOKEN_SINGLE;
530 t->tx_buf = &scratch->data_token;
531 spi_message_add_tail(t, m: &host->m);
532 }
533
534 /* Body of transfer is buffer, then CRC ...
535 * either TX-only, or RX with TX-ones.
536 */
537 t = &host->t;
538 memset(t, 0, sizeof(*t));
539 t->tx_buf = host->ones;
540 /* length and actual buffer info are written later */
541 spi_message_add_tail(t, m: &host->m);
542
543 t = &host->crc;
544 memset(t, 0, sizeof(*t));
545 t->len = 2;
546 if (write) {
547 /* the actual CRC may get written later */
548 t->tx_buf = &scratch->crc_val;
549 } else {
550 t->tx_buf = host->ones;
551 t->rx_buf = &scratch->crc_val;
552 }
553 spi_message_add_tail(t, m: &host->m);
554
555 /*
556 * A single block read is followed by N(EC) [0+] all-ones bytes
557 * before deselect ... don't bother.
558 *
559 * Multiblock reads are followed by N(AC) [1+] all-ones bytes before
560 * the next block is read, or a STOP_TRANSMISSION is issued. We'll
561 * collect that single byte, so readblock() doesn't need to.
562 *
563 * For a write, the one-byte data response follows immediately, then
564 * come zero or more busy bytes, then N(WR) [1+] all-ones bytes.
565 * Then single block reads may deselect, and multiblock ones issue
566 * the next token (next data block, or STOP_TRAN). We can try to
567 * minimize I/O ops by using a single read to collect end-of-busy.
568 */
569 if (multiple || write) {
570 t = &host->early_status;
571 memset(t, 0, sizeof(*t));
572 t->len = write ? sizeof(scratch->status) : 1;
573 t->tx_buf = host->ones;
574 t->rx_buf = scratch->status;
575 t->cs_change = 1;
576 spi_message_add_tail(t, m: &host->m);
577 }
578}
579
580/*
581 * Write one block:
582 * - caller handled preceding N(WR) [1+] all-ones bytes
583 * - data block
584 * + token
585 * + data bytes
586 * + crc16
587 * - an all-ones byte ... card writes a data-response byte
588 * - followed by N(EC) [0+] all-ones bytes, card writes zero/'busy'
589 *
590 * Return negative errno, else success.
591 */
592static int
593mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
594 unsigned long timeout)
595{
596 struct spi_device *spi = host->spi;
597 int status, i;
598 struct scratch *scratch = host->data;
599 u32 pattern;
600
601 if (host->mmc->use_spi_crc)
602 scratch->crc_val = cpu_to_be16(crc_itu_t(0, t->tx_buf, t->len));
603
604 status = spi_sync_locked(spi, message: &host->m);
605 if (status != 0) {
606 dev_dbg(&spi->dev, "write error (%d)\n", status);
607 return status;
608 }
609
610 /*
611 * Get the transmission data-response reply. It must follow
612 * immediately after the data block we transferred. This reply
613 * doesn't necessarily tell whether the write operation succeeded;
614 * it just says if the transmission was ok and whether *earlier*
615 * writes succeeded; see the standard.
616 *
617 * In practice, there are (even modern SDHC-)cards which are late
618 * in sending the response, and miss the time frame by a few bits,
619 * so we have to cope with this situation and check the response
620 * bit-by-bit. Arggh!!!
621 */
622 pattern = get_unaligned_be32(p: scratch->status);
623
624 /* First 3 bit of pattern are undefined */
625 pattern |= 0xE0000000;
626
627 /* left-adjust to leading 0 bit */
628 while (pattern & 0x80000000)
629 pattern <<= 1;
630 /* right-adjust for pattern matching. Code is in bit 4..0 now. */
631 pattern >>= 27;
632
633 switch (pattern) {
634 case SPI_RESPONSE_ACCEPTED:
635 status = 0;
636 break;
637 case SPI_RESPONSE_CRC_ERR:
638 /* host shall then issue MMC_STOP_TRANSMISSION */
639 status = -EILSEQ;
640 break;
641 case SPI_RESPONSE_WRITE_ERR:
642 /* host shall then issue MMC_STOP_TRANSMISSION,
643 * and should MMC_SEND_STATUS to sort it out
644 */
645 status = -EIO;
646 break;
647 default:
648 status = -EPROTO;
649 break;
650 }
651 if (status != 0) {
652 dev_dbg(&spi->dev, "write error %02x (%d)\n",
653 scratch->status[0], status);
654 return status;
655 }
656
657 t->tx_buf += t->len;
658
659 /* Return when not busy. If we didn't collect that status yet,
660 * we'll need some more I/O.
661 */
662 for (i = 4; i < sizeof(scratch->status); i++) {
663 /* card is non-busy if the most recent bit is 1 */
664 if (scratch->status[i] & 0x01)
665 return 0;
666 }
667 return mmc_spi_wait_unbusy(host, timeout);
668}
669
670/*
671 * Read one block:
672 * - skip leading all-ones bytes ... either
673 * + N(AC) [1..f(clock,CSD)] usually, else
674 * + N(CX) [0..8] when reading CSD or CID
675 * - data block
676 * + token ... if error token, no data or crc
677 * + data bytes
678 * + crc16
679 *
680 * After single block reads, we're done; N(EC) [0+] all-ones bytes follow
681 * before dropping chipselect.
682 *
683 * For multiblock reads, caller either reads the next block or issues a
684 * STOP_TRANSMISSION command.
685 */
686static int
687mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,
688 unsigned long timeout)
689{
690 struct spi_device *spi = host->spi;
691 int status;
692 struct scratch *scratch = host->data;
693 unsigned int bitshift;
694 u8 leftover;
695
696 /* At least one SD card sends an all-zeroes byte when N(CX)
697 * applies, before the all-ones bytes ... just cope with that.
698 */
699 status = mmc_spi_readbytes(host, len: 1);
700 if (status < 0)
701 return status;
702 status = scratch->status[0];
703 if (status == 0xff || status == 0)
704 status = mmc_spi_readtoken(host, timeout);
705
706 if (status < 0) {
707 dev_dbg(&spi->dev, "read error %02x (%d)\n", status, status);
708 return status;
709 }
710
711 /* The token may be bit-shifted...
712 * the first 0-bit precedes the data stream.
713 */
714 bitshift = 7;
715 while (status & 0x80) {
716 status <<= 1;
717 bitshift--;
718 }
719 leftover = status << 1;
720
721 status = spi_sync_locked(spi, message: &host->m);
722 if (status < 0) {
723 dev_dbg(&spi->dev, "read error %d\n", status);
724 return status;
725 }
726
727 if (bitshift) {
728 /* Walk through the data and the crc and do
729 * all the magic to get byte-aligned data.
730 */
731 u8 *cp = t->rx_buf;
732 unsigned int len;
733 unsigned int bitright = 8 - bitshift;
734 u8 temp;
735 for (len = t->len; len; len--) {
736 temp = *cp;
737 *cp++ = leftover | (temp >> bitshift);
738 leftover = temp << bitright;
739 }
740 cp = (u8 *) &scratch->crc_val;
741 temp = *cp;
742 *cp++ = leftover | (temp >> bitshift);
743 leftover = temp << bitright;
744 temp = *cp;
745 *cp = leftover | (temp >> bitshift);
746 }
747
748 if (host->mmc->use_spi_crc) {
749 u16 crc = crc_itu_t(crc: 0, buffer: t->rx_buf, len: t->len);
750
751 be16_to_cpus(&scratch->crc_val);
752 if (scratch->crc_val != crc) {
753 dev_dbg(&spi->dev,
754 "read - crc error: crc_val=0x%04x, computed=0x%04x len=%d\n",
755 scratch->crc_val, crc, t->len);
756 return -EILSEQ;
757 }
758 }
759
760 t->rx_buf += t->len;
761
762 return 0;
763}
764
765/*
766 * An MMC/SD data stage includes one or more blocks, optional CRCs,
767 * and inline handshaking. That handhaking makes it unlike most
768 * other SPI protocol stacks.
769 */
770static void
771mmc_spi_data_do(struct mmc_spi_host *host, struct mmc_command *cmd,
772 struct mmc_data *data, u32 blk_size)
773{
774 struct spi_device *spi = host->spi;
775 struct spi_transfer *t;
776 struct scatterlist *sg;
777 unsigned n_sg;
778 bool multiple = (data->blocks > 1);
779 bool write = (data->flags & MMC_DATA_WRITE);
780 const char *write_or_read = write ? "write" : "read";
781 u32 clock_rate;
782 unsigned long timeout;
783
784 mmc_spi_setup_data_message(host, multiple, write);
785 t = &host->t;
786
787 if (t->speed_hz)
788 clock_rate = t->speed_hz;
789 else
790 clock_rate = spi->max_speed_hz;
791
792 timeout = data->timeout_ns / 1000 +
793 data->timeout_clks * 1000000 / clock_rate;
794 timeout = usecs_to_jiffies(u: (unsigned int)timeout) + 1;
795
796 /* Handle scatterlist segments one at a time, with synch for
797 * each 512-byte block
798 */
799 for_each_sg(data->sg, sg, data->sg_len, n_sg) {
800 int status = 0;
801 void *kmap_addr;
802 unsigned length = sg->length;
803
804 /* allow pio too; we don't allow highmem */
805 kmap_addr = kmap(page: sg_page(sg));
806 if (write)
807 t->tx_buf = kmap_addr + sg->offset;
808 else
809 t->rx_buf = kmap_addr + sg->offset;
810
811 /* transfer each block, and update request status */
812 while (length) {
813 t->len = min(length, blk_size);
814
815 dev_dbg(&spi->dev, " %s block, %d bytes\n", write_or_read, t->len);
816
817 if (write)
818 status = mmc_spi_writeblock(host, t, timeout);
819 else
820 status = mmc_spi_readblock(host, t, timeout);
821 if (status < 0)
822 break;
823
824 data->bytes_xfered += t->len;
825 length -= t->len;
826
827 if (!multiple)
828 break;
829 }
830
831 /* discard mappings */
832 if (write)
833 /* nothing to do */;
834 else
835 flush_dcache_page(page: sg_page(sg));
836 kunmap(page: sg_page(sg));
837
838 if (status < 0) {
839 data->error = status;
840 dev_dbg(&spi->dev, "%s status %d\n", write_or_read, status);
841 break;
842 }
843 }
844
845 /* NOTE some docs describe an MMC-only SET_BLOCK_COUNT (CMD23) that
846 * can be issued before multiblock writes. Unlike its more widely
847 * documented analogue for SD cards (SET_WR_BLK_ERASE_COUNT, ACMD23),
848 * that can affect the STOP_TRAN logic. Complete (and current)
849 * MMC specs should sort that out before Linux starts using CMD23.
850 */
851 if (write && multiple) {
852 struct scratch *scratch = host->data;
853 int tmp;
854 const unsigned statlen = sizeof(scratch->status);
855
856 dev_dbg(&spi->dev, " STOP_TRAN\n");
857
858 /* Tweak the per-block message we set up earlier by morphing
859 * it to hold single buffer with the token followed by some
860 * all-ones bytes ... skip N(BR) (0..1), scan the rest for
861 * "not busy any longer" status, and leave chip selected.
862 */
863 INIT_LIST_HEAD(list: &host->m.transfers);
864 list_add(new: &host->early_status.transfer_list,
865 head: &host->m.transfers);
866
867 memset(scratch->status, 0xff, statlen);
868 scratch->status[0] = SPI_TOKEN_STOP_TRAN;
869
870 host->early_status.tx_buf = host->early_status.rx_buf;
871 host->early_status.len = statlen;
872
873 tmp = spi_sync_locked(spi, message: &host->m);
874 if (tmp < 0) {
875 if (!data->error)
876 data->error = tmp;
877 return;
878 }
879
880 /* Ideally we collected "not busy" status with one I/O,
881 * avoiding wasteful byte-at-a-time scanning... but more
882 * I/O is often needed.
883 */
884 for (tmp = 2; tmp < statlen; tmp++) {
885 if (scratch->status[tmp] != 0)
886 return;
887 }
888 tmp = mmc_spi_wait_unbusy(host, timeout);
889 if (tmp < 0 && !data->error)
890 data->error = tmp;
891 }
892}
893
894/****************************************************************************/
895
896/*
897 * MMC driver implementation -- the interface to the MMC stack
898 */
899
900static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
901{
902 struct mmc_spi_host *host = mmc_priv(host: mmc);
903 int status = -EINVAL;
904 int crc_retry = 5;
905 struct mmc_command stop;
906
907#ifdef DEBUG
908 /* MMC core and layered drivers *MUST* issue SPI-aware commands */
909 {
910 struct mmc_command *cmd;
911 int invalid = 0;
912
913 cmd = mrq->cmd;
914 if (!mmc_spi_resp_type(cmd)) {
915 dev_dbg(&host->spi->dev, "bogus command\n");
916 cmd->error = -EINVAL;
917 invalid = 1;
918 }
919
920 cmd = mrq->stop;
921 if (cmd && !mmc_spi_resp_type(cmd)) {
922 dev_dbg(&host->spi->dev, "bogus STOP command\n");
923 cmd->error = -EINVAL;
924 invalid = 1;
925 }
926
927 if (invalid) {
928 dump_stack();
929 mmc_request_done(host->mmc, mrq);
930 return;
931 }
932 }
933#endif
934
935 /* request exclusive bus access */
936 spi_bus_lock(ctlr: host->spi->controller);
937
938crc_recover:
939 /* issue command; then optionally data and stop */
940 status = mmc_spi_command_send(host, mrq, cmd: mrq->cmd, cs_on: mrq->data != NULL);
941 if (status == 0 && mrq->data) {
942 mmc_spi_data_do(host, cmd: mrq->cmd, data: mrq->data, blk_size: mrq->data->blksz);
943
944 /*
945 * The SPI bus is not always reliable for large data transfers.
946 * If an occasional crc error is reported by the SD device with
947 * data read/write over SPI, it may be recovered by repeating
948 * the last SD command again. The retry count is set to 5 to
949 * ensure the driver passes stress tests.
950 */
951 if (mrq->data->error == -EILSEQ && crc_retry) {
952 stop.opcode = MMC_STOP_TRANSMISSION;
953 stop.arg = 0;
954 stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
955 status = mmc_spi_command_send(host, mrq, cmd: &stop, cs_on: 0);
956 crc_retry--;
957 mrq->data->error = 0;
958 goto crc_recover;
959 }
960
961 if (mrq->stop)
962 status = mmc_spi_command_send(host, mrq, cmd: mrq->stop, cs_on: 0);
963 else
964 mmc_cs_off(host);
965 }
966
967 /* release the bus */
968 spi_bus_unlock(ctlr: host->spi->controller);
969
970 mmc_request_done(host->mmc, mrq);
971}
972
973/* See Section 6.4.1, in SD "Simplified Physical Layer Specification 2.0"
974 *
975 * NOTE that here we can't know that the card has just been powered up;
976 * not all MMC/SD sockets support power switching.
977 *
978 * FIXME when the card is still in SPI mode, e.g. from a previous kernel,
979 * this doesn't seem to do the right thing at all...
980 */
981static void mmc_spi_initsequence(struct mmc_spi_host *host)
982{
983 /* Try to be very sure any previous command has completed;
984 * wait till not-busy, skip debris from any old commands.
985 */
986 mmc_spi_wait_unbusy(host, timeout: msecs_to_jiffies(MMC_SPI_INIT_TIMEOUT_MS));
987 mmc_spi_readbytes(host, len: 10);
988
989 /*
990 * Do a burst with chipselect active-high. We need to do this to
991 * meet the requirement of 74 clock cycles with both chipselect
992 * and CMD (MOSI) high before CMD0 ... after the card has been
993 * powered up to Vdd(min), and so is ready to take commands.
994 *
995 * Some cards are particularly needy of this (e.g. Viking "SD256")
996 * while most others don't seem to care.
997 *
998 * Note that this is one of the places MMC/SD plays games with the
999 * SPI protocol. Another is that when chipselect is released while
1000 * the card returns BUSY status, the clock must issue several cycles
1001 * with chipselect high before the card will stop driving its output.
1002 *
1003 * SPI_CS_HIGH means "asserted" here. In some cases like when using
1004 * GPIOs for chip select, SPI_CS_HIGH is set but this will be logically
1005 * inverted by gpiolib, so if we want to ascertain to drive it high
1006 * we should toggle the default with an XOR as we do here.
1007 */
1008 host->spi->mode ^= SPI_CS_HIGH;
1009 if (spi_setup(spi: host->spi) != 0) {
1010 /* Just warn; most cards work without it. */
1011 dev_warn(&host->spi->dev,
1012 "can't change chip-select polarity\n");
1013 host->spi->mode ^= SPI_CS_HIGH;
1014 } else {
1015 mmc_spi_readbytes(host, len: 18);
1016
1017 host->spi->mode ^= SPI_CS_HIGH;
1018 if (spi_setup(spi: host->spi) != 0) {
1019 /* Wot, we can't get the same setup we had before? */
1020 dev_err(&host->spi->dev,
1021 "can't restore chip-select polarity\n");
1022 }
1023 }
1024}
1025
1026static char *mmc_powerstring(u8 power_mode)
1027{
1028 switch (power_mode) {
1029 case MMC_POWER_OFF: return "off";
1030 case MMC_POWER_UP: return "up";
1031 case MMC_POWER_ON: return "on";
1032 }
1033 return "?";
1034}
1035
1036static void mmc_spi_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
1037{
1038 struct mmc_spi_host *host = mmc_priv(host: mmc);
1039
1040 if (host->power_mode != ios->power_mode) {
1041 int canpower;
1042
1043 canpower = host->pdata && host->pdata->setpower;
1044
1045 dev_dbg(&host->spi->dev, "power %s (%d)%s\n",
1046 mmc_powerstring(ios->power_mode),
1047 ios->vdd,
1048 canpower ? ", can switch" : "");
1049
1050 /* switch power on/off if possible, accounting for
1051 * max 250msec powerup time if needed.
1052 */
1053 if (canpower) {
1054 switch (ios->power_mode) {
1055 case MMC_POWER_OFF:
1056 case MMC_POWER_UP:
1057 host->pdata->setpower(&host->spi->dev,
1058 ios->vdd);
1059 if (ios->power_mode == MMC_POWER_UP)
1060 msleep(msecs: host->powerup_msecs);
1061 }
1062 }
1063
1064 /* See 6.4.1 in the simplified SD card physical spec 2.0 */
1065 if (ios->power_mode == MMC_POWER_ON)
1066 mmc_spi_initsequence(host);
1067
1068 /* If powering down, ground all card inputs to avoid power
1069 * delivery from data lines! On a shared SPI bus, this
1070 * will probably be temporary; 6.4.2 of the simplified SD
1071 * spec says this must last at least 1msec.
1072 *
1073 * - Clock low means CPOL 0, e.g. mode 0
1074 * - MOSI low comes from writing zero
1075 * - Chipselect is usually active low...
1076 */
1077 if (canpower && ios->power_mode == MMC_POWER_OFF) {
1078 int mres;
1079 u8 nullbyte = 0;
1080
1081 host->spi->mode &= ~(SPI_CPOL|SPI_CPHA);
1082 mres = spi_setup(spi: host->spi);
1083 if (mres < 0)
1084 dev_dbg(&host->spi->dev,
1085 "switch to SPI mode 0 failed\n");
1086
1087 if (spi_write(spi: host->spi, buf: &nullbyte, len: 1) < 0)
1088 dev_dbg(&host->spi->dev,
1089 "put spi signals to low failed\n");
1090
1091 /*
1092 * Now clock should be low due to spi mode 0;
1093 * MOSI should be low because of written 0x00;
1094 * chipselect should be low (it is active low)
1095 * power supply is off, so now MMC is off too!
1096 *
1097 * FIXME no, chipselect can be high since the
1098 * device is inactive and SPI_CS_HIGH is clear...
1099 */
1100 msleep(msecs: 10);
1101 if (mres == 0) {
1102 host->spi->mode |= (SPI_CPOL|SPI_CPHA);
1103 mres = spi_setup(spi: host->spi);
1104 if (mres < 0)
1105 dev_dbg(&host->spi->dev,
1106 "switch back to SPI mode 3 failed\n");
1107 }
1108 }
1109
1110 host->power_mode = ios->power_mode;
1111 }
1112
1113 if (host->spi->max_speed_hz != ios->clock && ios->clock != 0) {
1114 int status;
1115
1116 host->spi->max_speed_hz = ios->clock;
1117 status = spi_setup(spi: host->spi);
1118 dev_dbg(&host->spi->dev, " clock to %d Hz, %d\n",
1119 host->spi->max_speed_hz, status);
1120 }
1121}
1122
1123static const struct mmc_host_ops mmc_spi_ops = {
1124 .request = mmc_spi_request,
1125 .set_ios = mmc_spi_set_ios,
1126 .get_ro = mmc_gpio_get_ro,
1127 .get_cd = mmc_gpio_get_cd,
1128};
1129
1130
1131/****************************************************************************/
1132
1133/*
1134 * SPI driver implementation
1135 */
1136
1137static irqreturn_t
1138mmc_spi_detect_irq(int irq, void *mmc)
1139{
1140 struct mmc_spi_host *host = mmc_priv(host: mmc);
1141 u16 delay_msec = max(host->pdata->detect_delay, (u16)100);
1142
1143 mmc_detect_change(mmc, delay: msecs_to_jiffies(m: delay_msec));
1144 return IRQ_HANDLED;
1145}
1146
1147static int mmc_spi_probe(struct spi_device *spi)
1148{
1149 void *ones;
1150 struct mmc_host *mmc;
1151 struct mmc_spi_host *host;
1152 int status;
1153 bool has_ro = false;
1154
1155 /* We rely on full duplex transfers, mostly to reduce
1156 * per-transfer overheads (by making fewer transfers).
1157 */
1158 if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX)
1159 return -EINVAL;
1160
1161 /* MMC and SD specs only seem to care that sampling is on the
1162 * rising edge ... meaning SPI modes 0 or 3. So either SPI mode
1163 * should be legit. We'll use mode 0 since the steady state is 0,
1164 * which is appropriate for hotplugging, unless the platform data
1165 * specify mode 3 (if hardware is not compatible to mode 0).
1166 */
1167 if (spi->mode != SPI_MODE_3)
1168 spi->mode = SPI_MODE_0;
1169 spi->bits_per_word = 8;
1170
1171 status = spi_setup(spi);
1172 if (status < 0) {
1173 dev_dbg(&spi->dev, "needs SPI mode %02x, %d KHz; %d\n",
1174 spi->mode, spi->max_speed_hz / 1000,
1175 status);
1176 return status;
1177 }
1178
1179 /* We need a supply of ones to transmit. This is the only time
1180 * the CPU touches these, so cache coherency isn't a concern.
1181 *
1182 * NOTE if many systems use more than one MMC-over-SPI connector
1183 * it'd save some memory to share this. That's evidently rare.
1184 */
1185 status = -ENOMEM;
1186 ones = kmalloc(MMC_SPI_BLOCKSIZE, GFP_KERNEL);
1187 if (!ones)
1188 goto nomem;
1189 memset(ones, 0xff, MMC_SPI_BLOCKSIZE);
1190
1191 mmc = mmc_alloc_host(extra: sizeof(*host), &spi->dev);
1192 if (!mmc)
1193 goto nomem;
1194
1195 mmc->ops = &mmc_spi_ops;
1196 mmc->max_blk_size = MMC_SPI_BLOCKSIZE;
1197 mmc->max_segs = MMC_SPI_BLOCKSATONCE;
1198 mmc->max_req_size = MMC_SPI_BLOCKSATONCE * MMC_SPI_BLOCKSIZE;
1199 mmc->max_blk_count = MMC_SPI_BLOCKSATONCE;
1200
1201 mmc->caps = MMC_CAP_SPI;
1202
1203 /* SPI doesn't need the lowspeed device identification thing for
1204 * MMC or SD cards, since it never comes up in open drain mode.
1205 * That's good; some SPI masters can't handle very low speeds!
1206 *
1207 * However, low speed SDIO cards need not handle over 400 KHz;
1208 * that's the only reason not to use a few MHz for f_min (until
1209 * the upper layer reads the target frequency from the CSD).
1210 */
1211 mmc->f_min = 400000;
1212 mmc->f_max = spi->max_speed_hz;
1213
1214 host = mmc_priv(host: mmc);
1215 host->mmc = mmc;
1216 host->spi = spi;
1217
1218 host->ones = ones;
1219
1220 dev_set_drvdata(dev: &spi->dev, data: mmc);
1221
1222 /* Platform data is used to hook up things like card sensing
1223 * and power switching gpios.
1224 */
1225 host->pdata = mmc_spi_get_pdata(spi);
1226 if (host->pdata)
1227 mmc->ocr_avail = host->pdata->ocr_mask;
1228 if (!mmc->ocr_avail) {
1229 dev_warn(&spi->dev, "ASSUMING 3.2-3.4 V slot power\n");
1230 mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34;
1231 }
1232 if (host->pdata && host->pdata->setpower) {
1233 host->powerup_msecs = host->pdata->powerup_msecs;
1234 if (!host->powerup_msecs || host->powerup_msecs > 250)
1235 host->powerup_msecs = 250;
1236 }
1237
1238 /* Preallocate buffers */
1239 host->data = kmalloc(size: sizeof(*host->data), GFP_KERNEL);
1240 if (!host->data)
1241 goto fail_nobuf1;
1242
1243 /* setup message for status/busy readback */
1244 spi_message_init(m: &host->readback);
1245
1246 spi_message_add_tail(t: &host->status, m: &host->readback);
1247 host->status.tx_buf = host->ones;
1248 host->status.rx_buf = &host->data->status;
1249 host->status.cs_change = 1;
1250
1251 /* register card detect irq */
1252 if (host->pdata && host->pdata->init) {
1253 status = host->pdata->init(&spi->dev, mmc_spi_detect_irq, mmc);
1254 if (status != 0)
1255 goto fail_glue_init;
1256 }
1257
1258 /* pass platform capabilities, if any */
1259 if (host->pdata) {
1260 mmc->caps |= host->pdata->caps;
1261 mmc->caps2 |= host->pdata->caps2;
1262 }
1263
1264 status = mmc_add_host(mmc);
1265 if (status != 0)
1266 goto fail_glue_init;
1267
1268 /*
1269 * Index 0 is card detect
1270 * Old boardfiles were specifying 1 ms as debounce
1271 */
1272 status = mmc_gpiod_request_cd(host: mmc, NULL, idx: 0, override_active_level: false, debounce: 1000);
1273 if (status == -EPROBE_DEFER)
1274 goto fail_gpiod_request;
1275 if (!status) {
1276 /*
1277 * The platform has a CD GPIO signal that may support
1278 * interrupts, so let mmc_gpiod_request_cd_irq() decide
1279 * if polling is needed or not.
1280 */
1281 mmc->caps &= ~MMC_CAP_NEEDS_POLL;
1282 mmc_gpiod_request_cd_irq(host: mmc);
1283 }
1284 mmc_detect_change(mmc, delay: 0);
1285
1286 /* Index 1 is write protect/read only */
1287 status = mmc_gpiod_request_ro(host: mmc, NULL, idx: 1, debounce: 0);
1288 if (status == -EPROBE_DEFER)
1289 goto fail_gpiod_request;
1290 if (!status)
1291 has_ro = true;
1292
1293 dev_info(&spi->dev, "SD/MMC host %s%s%s%s\n",
1294 dev_name(&mmc->class_dev),
1295 has_ro ? "" : ", no WP",
1296 (host->pdata && host->pdata->setpower)
1297 ? "" : ", no poweroff",
1298 (mmc->caps & MMC_CAP_NEEDS_POLL)
1299 ? ", cd polling" : "");
1300 return 0;
1301
1302fail_gpiod_request:
1303 mmc_remove_host(mmc);
1304fail_glue_init:
1305 kfree(objp: host->data);
1306fail_nobuf1:
1307 mmc_spi_put_pdata(spi);
1308 mmc_free_host(mmc);
1309nomem:
1310 kfree(objp: ones);
1311 return status;
1312}
1313
1314
1315static void mmc_spi_remove(struct spi_device *spi)
1316{
1317 struct mmc_host *mmc = dev_get_drvdata(dev: &spi->dev);
1318 struct mmc_spi_host *host = mmc_priv(host: mmc);
1319
1320 /* prevent new mmc_detect_change() calls */
1321 if (host->pdata && host->pdata->exit)
1322 host->pdata->exit(&spi->dev, mmc);
1323
1324 mmc_remove_host(mmc);
1325
1326 kfree(objp: host->data);
1327 kfree(objp: host->ones);
1328
1329 spi->max_speed_hz = mmc->f_max;
1330 mmc_spi_put_pdata(spi);
1331 mmc_free_host(mmc);
1332}
1333
1334static const struct spi_device_id mmc_spi_dev_ids[] = {
1335 { "mmc-spi-slot"},
1336 { },
1337};
1338MODULE_DEVICE_TABLE(spi, mmc_spi_dev_ids);
1339
1340static const struct of_device_id mmc_spi_of_match_table[] = {
1341 { .compatible = "mmc-spi-slot", },
1342 {},
1343};
1344MODULE_DEVICE_TABLE(of, mmc_spi_of_match_table);
1345
1346static struct spi_driver mmc_spi_driver = {
1347 .driver = {
1348 .name = "mmc_spi",
1349 .of_match_table = mmc_spi_of_match_table,
1350 },
1351 .id_table = mmc_spi_dev_ids,
1352 .probe = mmc_spi_probe,
1353 .remove = mmc_spi_remove,
1354};
1355
1356module_spi_driver(mmc_spi_driver);
1357
1358MODULE_AUTHOR("Mike Lavender, David Brownell, Hans-Peter Nilsson, Jan Nikitenko");
1359MODULE_DESCRIPTION("SPI SD/MMC host driver");
1360MODULE_LICENSE("GPL");
1361MODULE_ALIAS("spi:mmc_spi");
1362

source code of linux/drivers/mmc/host/mmc_spi.c