xref: /openbmc/linux/drivers/mmc/host/litex_mmc.c (revision 9a29f5fc)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * LiteX LiteSDCard driver
4  *
5  * Copyright (C) 2019-2020 Antmicro <contact@antmicro.com>
6  * Copyright (C) 2019-2020 Kamil Rakoczy <krakoczy@antmicro.com>
7  * Copyright (C) 2019-2020 Maciej Dudek <mdudek@internships.antmicro.com>
8  * Copyright (C) 2020 Paul Mackerras <paulus@ozlabs.org>
9  * Copyright (C) 2020-2022 Gabriel Somlo <gsomlo@gmail.com>
10  */
11 
12 #include <linux/bits.h>
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/dma-mapping.h>
16 #include <linux/interrupt.h>
17 #include <linux/iopoll.h>
18 #include <linux/litex.h>
19 #include <linux/mod_devicetable.h>
20 #include <linux/module.h>
21 #include <linux/platform_device.h>
22 
23 #include <linux/mmc/host.h>
24 #include <linux/mmc/mmc.h>
25 #include <linux/mmc/sd.h>
26 
27 #define LITEX_PHY_CARDDETECT  0x00
28 #define LITEX_PHY_CLOCKERDIV  0x04
29 #define LITEX_PHY_INITIALIZE  0x08
30 #define LITEX_PHY_WRITESTATUS 0x0C
31 #define LITEX_CORE_CMDARG     0x00
32 #define LITEX_CORE_CMDCMD     0x04
33 #define LITEX_CORE_CMDSND     0x08
34 #define LITEX_CORE_CMDRSP     0x0C
35 #define LITEX_CORE_CMDEVT     0x1C
36 #define LITEX_CORE_DATEVT     0x20
37 #define LITEX_CORE_BLKLEN     0x24
38 #define LITEX_CORE_BLKCNT     0x28
39 #define LITEX_BLK2MEM_BASE    0x00
40 #define LITEX_BLK2MEM_LEN     0x08
41 #define LITEX_BLK2MEM_ENA     0x0C
42 #define LITEX_BLK2MEM_DONE    0x10
43 #define LITEX_BLK2MEM_LOOP    0x14
44 #define LITEX_MEM2BLK_BASE    0x00
45 #define LITEX_MEM2BLK_LEN     0x08
46 #define LITEX_MEM2BLK_ENA     0x0C
47 #define LITEX_MEM2BLK_DONE    0x10
48 #define LITEX_MEM2BLK_LOOP    0x14
49 #define LITEX_MEM2BLK         0x18
50 #define LITEX_IRQ_STATUS      0x00
51 #define LITEX_IRQ_PENDING     0x04
52 #define LITEX_IRQ_ENABLE      0x08
53 
54 #define SD_CTL_DATA_XFER_NONE  0
55 #define SD_CTL_DATA_XFER_READ  1
56 #define SD_CTL_DATA_XFER_WRITE 2
57 
58 #define SD_CTL_RESP_NONE       0
59 #define SD_CTL_RESP_SHORT      1
60 #define SD_CTL_RESP_LONG       2
61 #define SD_CTL_RESP_SHORT_BUSY 3
62 
63 #define SD_BIT_DONE    BIT(0)
64 #define SD_BIT_WR_ERR  BIT(1)
65 #define SD_BIT_TIMEOUT BIT(2)
66 #define SD_BIT_CRC_ERR BIT(3)
67 
68 #define SD_SLEEP_US       5
69 #define SD_TIMEOUT_US 20000
70 
71 #define SDIRQ_CARD_DETECT    1
72 #define SDIRQ_SD_TO_MEM_DONE 2
73 #define SDIRQ_MEM_TO_SD_DONE 4
74 #define SDIRQ_CMD_DONE       8
75 
76 struct litex_mmc_host {
77 	struct mmc_host *mmc;
78 
79 	void __iomem *sdphy;
80 	void __iomem *sdcore;
81 	void __iomem *sdreader;
82 	void __iomem *sdwriter;
83 	void __iomem *sdirq;
84 
85 	void *buffer;
86 	size_t buf_size;
87 	dma_addr_t dma;
88 
89 	struct completion cmd_done;
90 	int irq;
91 
92 	unsigned int ref_clk;
93 	unsigned int sd_clk;
94 
95 	u32 resp[4];
96 	u16 rca;
97 
98 	bool is_bus_width_set;
99 	bool app_cmd;
100 };
101 
102 static int litex_mmc_sdcard_wait_done(void __iomem *reg, struct device *dev)
103 {
104 	u8 evt;
105 	int ret;
106 
107 	ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
108 				 SD_SLEEP_US, SD_TIMEOUT_US);
109 	if (ret)
110 		return ret;
111 	if (evt == SD_BIT_DONE)
112 		return 0;
113 	if (evt & SD_BIT_WR_ERR)
114 		return -EIO;
115 	if (evt & SD_BIT_TIMEOUT)
116 		return -ETIMEDOUT;
117 	if (evt & SD_BIT_CRC_ERR)
118 		return -EILSEQ;
119 	dev_err(dev, "%s: unknown error (evt=%x)\n", __func__, evt);
120 	return -EINVAL;
121 }
122 
123 static int litex_mmc_send_cmd(struct litex_mmc_host *host,
124 			      u8 cmd, u32 arg, u8 response_len, u8 transfer)
125 {
126 	struct device *dev = mmc_dev(host->mmc);
127 	void __iomem *reg;
128 	int ret;
129 	u8 evt;
130 
131 	litex_write32(host->sdcore + LITEX_CORE_CMDARG, arg);
132 	litex_write32(host->sdcore + LITEX_CORE_CMDCMD,
133 		      cmd << 8 | transfer << 5 | response_len);
134 	litex_write8(host->sdcore + LITEX_CORE_CMDSND, 1);
135 
136 	/*
137 	 * Wait for an interrupt if we have an interrupt and either there is
138 	 * data to be transferred, or if the card can report busy via DAT0.
139 	 */
140 	if (host->irq > 0 &&
141 	    (transfer != SD_CTL_DATA_XFER_NONE ||
142 	     response_len == SD_CTL_RESP_SHORT_BUSY)) {
143 		reinit_completion(&host->cmd_done);
144 		litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
145 			      SDIRQ_CMD_DONE | SDIRQ_CARD_DETECT);
146 		wait_for_completion(&host->cmd_done);
147 	}
148 
149 	ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_CMDEVT, dev);
150 	if (ret) {
151 		dev_err(dev, "Command (cmd %d) error, status %d\n", cmd, ret);
152 		return ret;
153 	}
154 
155 	if (response_len != SD_CTL_RESP_NONE) {
156 		/*
157 		 * NOTE: this matches the semantics of litex_read32()
158 		 * regardless of underlying arch endianness!
159 		 */
160 		memcpy_fromio(host->resp,
161 			      host->sdcore + LITEX_CORE_CMDRSP, 0x10);
162 	}
163 
164 	if (!host->app_cmd && cmd == SD_SEND_RELATIVE_ADDR)
165 		host->rca = (host->resp[3] >> 16);
166 
167 	host->app_cmd = (cmd == MMC_APP_CMD);
168 
169 	if (transfer == SD_CTL_DATA_XFER_NONE)
170 		return ret; /* OK from prior litex_mmc_sdcard_wait_done() */
171 
172 	ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_DATEVT, dev);
173 	if (ret) {
174 		dev_err(dev, "Data xfer (cmd %d) error, status %d\n", cmd, ret);
175 		return ret;
176 	}
177 
178 	/* Wait for completion of (read or write) DMA transfer */
179 	reg = (transfer == SD_CTL_DATA_XFER_READ) ?
180 		host->sdreader + LITEX_BLK2MEM_DONE :
181 		host->sdwriter + LITEX_MEM2BLK_DONE;
182 	ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
183 				 SD_SLEEP_US, SD_TIMEOUT_US);
184 	if (ret)
185 		dev_err(dev, "DMA timeout (cmd %d)\n", cmd);
186 
187 	return ret;
188 }
189 
190 static int litex_mmc_send_app_cmd(struct litex_mmc_host *host)
191 {
192 	return litex_mmc_send_cmd(host, MMC_APP_CMD, host->rca << 16,
193 				  SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
194 }
195 
196 static int litex_mmc_send_set_bus_w_cmd(struct litex_mmc_host *host, u32 width)
197 {
198 	return litex_mmc_send_cmd(host, SD_APP_SET_BUS_WIDTH, width,
199 				  SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
200 }
201 
202 static int litex_mmc_set_bus_width(struct litex_mmc_host *host)
203 {
204 	bool app_cmd_sent;
205 	int ret;
206 
207 	if (host->is_bus_width_set)
208 		return 0;
209 
210 	/* Ensure 'app_cmd' precedes 'app_set_bus_width_cmd' */
211 	app_cmd_sent = host->app_cmd; /* was preceding command app_cmd? */
212 	if (!app_cmd_sent) {
213 		ret = litex_mmc_send_app_cmd(host);
214 		if (ret)
215 			return ret;
216 	}
217 
218 	/* LiteSDCard only supports 4-bit bus width */
219 	ret = litex_mmc_send_set_bus_w_cmd(host, MMC_BUS_WIDTH_4);
220 	if (ret)
221 		return ret;
222 
223 	/* Re-send 'app_cmd' if necessary */
224 	if (app_cmd_sent) {
225 		ret = litex_mmc_send_app_cmd(host);
226 		if (ret)
227 			return ret;
228 	}
229 
230 	host->is_bus_width_set = true;
231 
232 	return 0;
233 }
234 
235 static int litex_mmc_get_cd(struct mmc_host *mmc)
236 {
237 	struct litex_mmc_host *host = mmc_priv(mmc);
238 	int ret;
239 
240 	if (!mmc_card_is_removable(mmc))
241 		return 1;
242 
243 	ret = !litex_read8(host->sdphy + LITEX_PHY_CARDDETECT);
244 	if (ret)
245 		return ret;
246 
247 	/* Ensure bus width will be set (again) upon card (re)insertion */
248 	host->is_bus_width_set = false;
249 
250 	return 0;
251 }
252 
253 static irqreturn_t litex_mmc_interrupt(int irq, void *arg)
254 {
255 	struct mmc_host *mmc = arg;
256 	struct litex_mmc_host *host = mmc_priv(mmc);
257 	u32 pending = litex_read32(host->sdirq + LITEX_IRQ_PENDING);
258 	irqreturn_t ret = IRQ_NONE;
259 
260 	/* Check for card change interrupt */
261 	if (pending & SDIRQ_CARD_DETECT) {
262 		litex_write32(host->sdirq + LITEX_IRQ_PENDING,
263 			      SDIRQ_CARD_DETECT);
264 		mmc_detect_change(mmc, msecs_to_jiffies(10));
265 		ret = IRQ_HANDLED;
266 	}
267 
268 	/* Check for command completed */
269 	if (pending & SDIRQ_CMD_DONE) {
270 		/* Disable it so it doesn't keep interrupting */
271 		litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
272 			      SDIRQ_CARD_DETECT);
273 		complete(&host->cmd_done);
274 		ret = IRQ_HANDLED;
275 	}
276 
277 	return ret;
278 }
279 
280 static u32 litex_mmc_response_len(struct mmc_command *cmd)
281 {
282 	if (cmd->flags & MMC_RSP_136)
283 		return SD_CTL_RESP_LONG;
284 	if (!(cmd->flags & MMC_RSP_PRESENT))
285 		return SD_CTL_RESP_NONE;
286 	if (cmd->flags & MMC_RSP_BUSY)
287 		return SD_CTL_RESP_SHORT_BUSY;
288 	return SD_CTL_RESP_SHORT;
289 }
290 
291 static void litex_mmc_do_dma(struct litex_mmc_host *host, struct mmc_data *data,
292 			     unsigned int *len, bool *direct, u8 *transfer)
293 {
294 	struct device *dev = mmc_dev(host->mmc);
295 	dma_addr_t dma;
296 	int sg_count;
297 
298 	/*
299 	 * Try to DMA directly to/from the data buffer.
300 	 * We can do that if the buffer can be mapped for DMA
301 	 * in one contiguous chunk.
302 	 */
303 	dma = host->dma;
304 	*len = data->blksz * data->blocks;
305 	sg_count = dma_map_sg(dev, data->sg, data->sg_len,
306 			      mmc_get_dma_dir(data));
307 	if (sg_count == 1) {
308 		dma = sg_dma_address(data->sg);
309 		*len = sg_dma_len(data->sg);
310 		*direct = true;
311 	} else if (*len > host->buf_size)
312 		*len = host->buf_size;
313 
314 	if (data->flags & MMC_DATA_READ) {
315 		litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
316 		litex_write64(host->sdreader + LITEX_BLK2MEM_BASE, dma);
317 		litex_write32(host->sdreader + LITEX_BLK2MEM_LEN, *len);
318 		litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 1);
319 		*transfer = SD_CTL_DATA_XFER_READ;
320 	} else if (data->flags & MMC_DATA_WRITE) {
321 		if (!*direct)
322 			sg_copy_to_buffer(data->sg, data->sg_len,
323 					  host->buffer, *len);
324 		litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
325 		litex_write64(host->sdwriter + LITEX_MEM2BLK_BASE, dma);
326 		litex_write32(host->sdwriter + LITEX_MEM2BLK_LEN, *len);
327 		litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 1);
328 		*transfer = SD_CTL_DATA_XFER_WRITE;
329 	} else {
330 		dev_warn(dev, "Data present w/o read or write flag.\n");
331 		/* Continue: set cmd status, mark req done */
332 	}
333 
334 	litex_write16(host->sdcore + LITEX_CORE_BLKLEN, data->blksz);
335 	litex_write32(host->sdcore + LITEX_CORE_BLKCNT, data->blocks);
336 }
337 
338 static void litex_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
339 {
340 	struct litex_mmc_host *host = mmc_priv(mmc);
341 	struct device *dev = mmc_dev(mmc);
342 	struct mmc_command *cmd = mrq->cmd;
343 	struct mmc_command *sbc = mrq->sbc;
344 	struct mmc_data *data = mrq->data;
345 	struct mmc_command *stop = mrq->stop;
346 	unsigned int retries = cmd->retries;
347 	unsigned int len = 0;
348 	bool direct = false;
349 	u32 response_len = litex_mmc_response_len(cmd);
350 	u8 transfer = SD_CTL_DATA_XFER_NONE;
351 
352 	/* First check that the card is still there */
353 	if (!litex_mmc_get_cd(mmc)) {
354 		cmd->error = -ENOMEDIUM;
355 		mmc_request_done(mmc, mrq);
356 		return;
357 	}
358 
359 	/* Send set-block-count command if needed */
360 	if (sbc) {
361 		sbc->error = litex_mmc_send_cmd(host, sbc->opcode, sbc->arg,
362 						litex_mmc_response_len(sbc),
363 						SD_CTL_DATA_XFER_NONE);
364 		if (sbc->error) {
365 			host->is_bus_width_set = false;
366 			mmc_request_done(mmc, mrq);
367 			return;
368 		}
369 	}
370 
371 	if (data) {
372 		/*
373 		 * LiteSDCard only supports 4-bit bus width; therefore, we MUST
374 		 * inject a SET_BUS_WIDTH (acmd6) before the very first data
375 		 * transfer, earlier than when the mmc subsystem would normally
376 		 * get around to it!
377 		 */
378 		cmd->error = litex_mmc_set_bus_width(host);
379 		if (cmd->error) {
380 			dev_err(dev, "Can't set bus width!\n");
381 			mmc_request_done(mmc, mrq);
382 			return;
383 		}
384 
385 		litex_mmc_do_dma(host, data, &len, &direct, &transfer);
386 	}
387 
388 	do {
389 		cmd->error = litex_mmc_send_cmd(host, cmd->opcode, cmd->arg,
390 						response_len, transfer);
391 	} while (cmd->error && retries-- > 0);
392 
393 	if (cmd->error) {
394 		/* Card may be gone; don't assume bus width is still set */
395 		host->is_bus_width_set = false;
396 	}
397 
398 	if (response_len == SD_CTL_RESP_SHORT) {
399 		/* Pull short response fields from appropriate host registers */
400 		cmd->resp[0] = host->resp[3];
401 		cmd->resp[1] = host->resp[2] & 0xFF;
402 	} else if (response_len == SD_CTL_RESP_LONG) {
403 		cmd->resp[0] = host->resp[0];
404 		cmd->resp[1] = host->resp[1];
405 		cmd->resp[2] = host->resp[2];
406 		cmd->resp[3] = host->resp[3];
407 	}
408 
409 	/* Send stop-transmission command if required */
410 	if (stop && (cmd->error || !sbc)) {
411 		stop->error = litex_mmc_send_cmd(host, stop->opcode, stop->arg,
412 						 litex_mmc_response_len(stop),
413 						 SD_CTL_DATA_XFER_NONE);
414 		if (stop->error)
415 			host->is_bus_width_set = false;
416 	}
417 
418 	if (data) {
419 		dma_unmap_sg(dev, data->sg, data->sg_len,
420 			     mmc_get_dma_dir(data));
421 	}
422 
423 	if (!cmd->error && transfer != SD_CTL_DATA_XFER_NONE) {
424 		data->bytes_xfered = min(len, mmc->max_req_size);
425 		if (transfer == SD_CTL_DATA_XFER_READ && !direct) {
426 			sg_copy_from_buffer(data->sg, sg_nents(data->sg),
427 					    host->buffer, data->bytes_xfered);
428 		}
429 	}
430 
431 	mmc_request_done(mmc, mrq);
432 }
433 
434 static void litex_mmc_setclk(struct litex_mmc_host *host, unsigned int freq)
435 {
436 	struct device *dev = mmc_dev(host->mmc);
437 	u32 div;
438 
439 	div = freq ? host->ref_clk / freq : 256U;
440 	div = roundup_pow_of_two(div);
441 	div = clamp(div, 2U, 256U);
442 	dev_dbg(dev, "sd_clk_freq=%d: set to %d via div=%d\n",
443 		freq, host->ref_clk / div, div);
444 	litex_write16(host->sdphy + LITEX_PHY_CLOCKERDIV, div);
445 	host->sd_clk = freq;
446 }
447 
448 static void litex_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
449 {
450 	struct litex_mmc_host *host = mmc_priv(mmc);
451 
452 	/*
453 	 * NOTE: Ignore any ios->bus_width updates; they occur right after
454 	 * the mmc core sends its own acmd6 bus-width change notification,
455 	 * which is redundant since we snoop on the command flow and inject
456 	 * an early acmd6 before the first data transfer command is sent!
457 	 */
458 
459 	/* Update sd_clk */
460 	if (ios->clock != host->sd_clk)
461 		litex_mmc_setclk(host, ios->clock);
462 }
463 
464 static const struct mmc_host_ops litex_mmc_ops = {
465 	.get_cd = litex_mmc_get_cd,
466 	.request = litex_mmc_request,
467 	.set_ios = litex_mmc_set_ios,
468 };
469 
470 static int litex_mmc_irq_init(struct platform_device *pdev,
471 			      struct litex_mmc_host *host)
472 {
473 	struct device *dev = mmc_dev(host->mmc);
474 	int ret;
475 
476 	ret = platform_get_irq_optional(pdev, 0);
477 	if (ret < 0 && ret != -ENXIO)
478 		return ret;
479 	if (ret > 0)
480 		host->irq = ret;
481 	else {
482 		dev_warn(dev, "Failed to get IRQ, using polling\n");
483 		goto use_polling;
484 	}
485 
486 	host->sdirq = devm_platform_ioremap_resource_byname(pdev, "irq");
487 	if (IS_ERR(host->sdirq))
488 		return PTR_ERR(host->sdirq);
489 
490 	ret = devm_request_irq(dev, host->irq, litex_mmc_interrupt, 0,
491 			       "litex-mmc", host->mmc);
492 	if (ret < 0) {
493 		dev_warn(dev, "IRQ request error %d, using polling\n", ret);
494 		goto use_polling;
495 	}
496 
497 	/* Clear & enable card-change interrupts */
498 	litex_write32(host->sdirq + LITEX_IRQ_PENDING, SDIRQ_CARD_DETECT);
499 	litex_write32(host->sdirq + LITEX_IRQ_ENABLE, SDIRQ_CARD_DETECT);
500 
501 	return 0;
502 
503 use_polling:
504 	host->mmc->caps |= MMC_CAP_NEEDS_POLL;
505 	return 0;
506 }
507 
508 static void litex_mmc_free_host_wrapper(void *mmc)
509 {
510 	mmc_free_host(mmc);
511 }
512 
513 static int litex_mmc_probe(struct platform_device *pdev)
514 {
515 	struct device *dev = &pdev->dev;
516 	struct litex_mmc_host *host;
517 	struct mmc_host *mmc;
518 	struct clk *clk;
519 	int ret;
520 
521 	/*
522 	 * NOTE: defaults to max_[req,seg]_size=PAGE_SIZE, max_blk_size=512,
523 	 * and max_blk_count accordingly set to 8;
524 	 * If for some reason we need to modify max_blk_count, we must also
525 	 * re-calculate `max_[req,seg]_size = max_blk_size * max_blk_count;`
526 	 */
527 	mmc = mmc_alloc_host(sizeof(struct litex_mmc_host), dev);
528 	if (!mmc)
529 		return -ENOMEM;
530 
531 	ret = devm_add_action_or_reset(dev, litex_mmc_free_host_wrapper, mmc);
532 	if (ret)
533 		return dev_err_probe(dev, ret,
534 				     "Can't register mmc_free_host action\n");
535 
536 	host = mmc_priv(mmc);
537 	host->mmc = mmc;
538 
539 	/* Initialize clock source */
540 	clk = devm_clk_get(dev, NULL);
541 	if (IS_ERR(clk))
542 		return dev_err_probe(dev, PTR_ERR(clk), "can't get clock\n");
543 	host->ref_clk = clk_get_rate(clk);
544 	host->sd_clk = 0;
545 
546 	/*
547 	 * LiteSDCard only supports 4-bit bus width; therefore, we MUST inject
548 	 * a SET_BUS_WIDTH (acmd6) before the very first data transfer, earlier
549 	 * than when the mmc subsystem would normally get around to it!
550 	 */
551 	host->is_bus_width_set = false;
552 	host->app_cmd = false;
553 
554 	/* LiteSDCard can support 64-bit DMA addressing */
555 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
556 	if (ret)
557 		return ret;
558 
559 	host->buf_size = mmc->max_req_size * 2;
560 	host->buffer = dmam_alloc_coherent(dev, host->buf_size,
561 					   &host->dma, GFP_KERNEL);
562 	if (host->buffer == NULL)
563 		return -ENOMEM;
564 
565 	host->sdphy = devm_platform_ioremap_resource_byname(pdev, "phy");
566 	if (IS_ERR(host->sdphy))
567 		return PTR_ERR(host->sdphy);
568 
569 	host->sdcore = devm_platform_ioremap_resource_byname(pdev, "core");
570 	if (IS_ERR(host->sdcore))
571 		return PTR_ERR(host->sdcore);
572 
573 	host->sdreader = devm_platform_ioremap_resource_byname(pdev, "reader");
574 	if (IS_ERR(host->sdreader))
575 		return PTR_ERR(host->sdreader);
576 
577 	host->sdwriter = devm_platform_ioremap_resource_byname(pdev, "writer");
578 	if (IS_ERR(host->sdwriter))
579 		return PTR_ERR(host->sdwriter);
580 
581 	/* Ensure DMA bus masters are disabled */
582 	litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
583 	litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
584 
585 	init_completion(&host->cmd_done);
586 	ret = litex_mmc_irq_init(pdev, host);
587 	if (ret)
588 		return ret;
589 
590 	mmc->ops = &litex_mmc_ops;
591 
592 	ret = mmc_regulator_get_supply(mmc);
593 	if (ret || mmc->ocr_avail == 0) {
594 		dev_warn(dev, "can't get voltage, defaulting to 3.3V\n");
595 		mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
596 	}
597 
598 	/*
599 	 * Set default sd_clk frequency range based on empirical observations
600 	 * of LiteSDCard gateware behavior on typical SDCard media
601 	 */
602 	mmc->f_min = 12.5e6;
603 	mmc->f_max = 50e6;
604 
605 	ret = mmc_of_parse(mmc);
606 	if (ret)
607 		return ret;
608 
609 	/* Force 4-bit bus_width (only width supported by hardware) */
610 	mmc->caps &= ~MMC_CAP_8_BIT_DATA;
611 	mmc->caps |= MMC_CAP_4_BIT_DATA;
612 
613 	/* Set default capabilities */
614 	mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
615 		     MMC_CAP_DRIVER_TYPE_D |
616 		     MMC_CAP_CMD23;
617 	mmc->caps2 |= MMC_CAP2_NO_WRITE_PROTECT |
618 		      MMC_CAP2_NO_SDIO |
619 		      MMC_CAP2_NO_MMC;
620 
621 	platform_set_drvdata(pdev, host);
622 
623 	ret = mmc_add_host(mmc);
624 	if (ret)
625 		return ret;
626 
627 	dev_info(dev, "LiteX MMC controller initialized.\n");
628 	return 0;
629 }
630 
631 static int litex_mmc_remove(struct platform_device *pdev)
632 {
633 	struct litex_mmc_host *host = platform_get_drvdata(pdev);
634 
635 	mmc_remove_host(host->mmc);
636 	return 0;
637 }
638 
639 static const struct of_device_id litex_match[] = {
640 	{ .compatible = "litex,mmc" },
641 	{ }
642 };
643 MODULE_DEVICE_TABLE(of, litex_match);
644 
645 static struct platform_driver litex_mmc_driver = {
646 	.probe = litex_mmc_probe,
647 	.remove = litex_mmc_remove,
648 	.driver = {
649 		.name = "litex-mmc",
650 		.of_match_table = litex_match,
651 	},
652 };
653 module_platform_driver(litex_mmc_driver);
654 
655 MODULE_DESCRIPTION("LiteX SDCard driver");
656 MODULE_AUTHOR("Antmicro <contact@antmicro.com>");
657 MODULE_AUTHOR("Kamil Rakoczy <krakoczy@antmicro.com>");
658 MODULE_AUTHOR("Maciej Dudek <mdudek@internships.antmicro.com>");
659 MODULE_AUTHOR("Paul Mackerras <paulus@ozlabs.org>");
660 MODULE_AUTHOR("Gabriel Somlo <gsomlo@gmail.com>");
661 MODULE_LICENSE("GPL v2");
662