xref: /linux/drivers/mmc/host/cb710-mmc.c (revision cea0f76a483d1270ac6f6513964e3e75193dda48)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  cb710/mmc.c
4  *
5  *  Copyright by Michał Mirosław, 2008-2009
6  */
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/pci.h>
10 #include <linux/delay.h>
11 #include "cb710-mmc.h"
12 
13 #define CB710_MMC_REQ_TIMEOUT_MS	2000
14 
15 static const u8 cb710_clock_divider_log2[8] = {
16 /*	1, 2, 4, 8, 16, 32, 128, 512 */
17 	0, 1, 2, 3,  4,  5,   7,   9
18 };
19 #define CB710_MAX_DIVIDER_IDX	\
20 	(ARRAY_SIZE(cb710_clock_divider_log2) - 1)
21 
22 static const u8 cb710_src_freq_mhz[16] = {
23 	33, 10, 20, 25, 30, 35, 40, 45,
24 	50, 55, 60, 65, 70, 75, 80, 85
25 };
26 
27 static void cb710_mmc_select_clock_divider(struct mmc_host *mmc, int hz)
28 {
29 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
30 	struct pci_dev *pdev = cb710_slot_to_chip(slot)->pdev;
31 	u32 src_freq_idx;
32 	u32 divider_idx;
33 	int src_hz;
34 
35 	/* on CB710 in HP nx9500:
36 	 *   src_freq_idx == 0
37 	 *   indexes 1-7 work as written in the table
38 	 *   indexes 0,8-15 give no clock output
39 	 */
40 	pci_read_config_dword(pdev, 0x48, &src_freq_idx);
41 	src_freq_idx = (src_freq_idx >> 16) & 0xF;
42 	src_hz = cb710_src_freq_mhz[src_freq_idx] * 1000000;
43 
44 	for (divider_idx = 0; divider_idx < CB710_MAX_DIVIDER_IDX; ++divider_idx) {
45 		if (hz >= src_hz >> cb710_clock_divider_log2[divider_idx])
46 			break;
47 	}
48 
49 	if (src_freq_idx)
50 		divider_idx |= 0x8;
51 	else if (divider_idx == 0)
52 		divider_idx = 1;
53 
54 	cb710_pci_update_config_reg(pdev, 0x40, ~0xF0000000, divider_idx << 28);
55 
56 	dev_dbg(cb710_slot_dev(slot),
57 		"clock set to %d Hz, wanted %d Hz; src_freq_idx = %d, divider_idx = %d|%d\n",
58 		src_hz >> cb710_clock_divider_log2[divider_idx & 7],
59 		hz, src_freq_idx, divider_idx & 7, divider_idx & 8);
60 }
61 
62 static void __cb710_mmc_enable_irq(struct cb710_slot *slot,
63 	unsigned short enable, unsigned short mask)
64 {
65 	/* clear global IE
66 	 * - it gets set later if any interrupt sources are enabled */
67 	mask |= CB710_MMC_IE_IRQ_ENABLE;
68 
69 	/* look like interrupt is fired whenever
70 	 * WORD[0x0C] & WORD[0x10] != 0;
71 	 * -> bit 15 port 0x0C seems to be global interrupt enable
72 	 */
73 
74 	enable = (cb710_read_port_16(slot, CB710_MMC_IRQ_ENABLE_PORT)
75 		& ~mask) | enable;
76 
77 	if (enable)
78 		enable |= CB710_MMC_IE_IRQ_ENABLE;
79 
80 	cb710_write_port_16(slot, CB710_MMC_IRQ_ENABLE_PORT, enable);
81 }
82 
83 static void cb710_mmc_enable_irq(struct cb710_slot *slot,
84 	unsigned short enable, unsigned short mask)
85 {
86 	struct cb710_mmc_reader *reader = mmc_priv(cb710_slot_to_mmc(slot));
87 	unsigned long flags;
88 
89 	spin_lock_irqsave(&reader->irq_lock, flags);
90 	/* this is the only thing irq_lock protects */
91 	__cb710_mmc_enable_irq(slot, enable, mask);
92 	spin_unlock_irqrestore(&reader->irq_lock, flags);
93 }
94 
95 static void cb710_mmc_reset_events(struct cb710_slot *slot)
96 {
97 	cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT, 0xFF);
98 	cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT, 0xFF);
99 	cb710_write_port_8(slot, CB710_MMC_STATUS2_PORT, 0xFF);
100 }
101 
102 static void cb710_mmc_enable_4bit_data(struct cb710_slot *slot, int enable)
103 {
104 	if (enable)
105 		cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT,
106 			CB710_MMC_C1_4BIT_DATA_BUS, 0);
107 	else
108 		cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT,
109 			0, CB710_MMC_C1_4BIT_DATA_BUS);
110 }
111 
112 static int cb710_check_event(struct cb710_slot *slot, u8 what)
113 {
114 	u16 status;
115 
116 	status = cb710_read_port_16(slot, CB710_MMC_STATUS_PORT);
117 
118 	if (status & CB710_MMC_S0_FIFO_UNDERFLOW) {
119 		/* it is just a guess, so log it */
120 		dev_dbg(cb710_slot_dev(slot),
121 			"CHECK : ignoring bit 6 in status %04X\n", status);
122 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT,
123 			CB710_MMC_S0_FIFO_UNDERFLOW);
124 		status &= ~CB710_MMC_S0_FIFO_UNDERFLOW;
125 	}
126 
127 	if (status & CB710_MMC_STATUS_ERROR_EVENTS) {
128 		dev_dbg(cb710_slot_dev(slot),
129 			"CHECK : returning EIO on status %04X\n", status);
130 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT, status & 0xFF);
131 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT,
132 			CB710_MMC_S1_RESET);
133 		return -EIO;
134 	}
135 
136 	/* 'what' is a bit in MMC_STATUS1 */
137 	if ((status >> 8) & what) {
138 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT, what);
139 		return 1;
140 	}
141 
142 	return 0;
143 }
144 
145 static int cb710_wait_for_event(struct cb710_slot *slot, u8 what)
146 {
147 	int err = 0;
148 	unsigned limit = 2000000;	/* FIXME: real timeout */
149 
150 #ifdef CONFIG_CB710_DEBUG
151 	u32 e, x;
152 	e = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
153 #endif
154 
155 	while (!(err = cb710_check_event(slot, what))) {
156 		if (!--limit) {
157 			cb710_dump_regs(cb710_slot_to_chip(slot),
158 				CB710_DUMP_REGS_MMC);
159 			err = -ETIMEDOUT;
160 			break;
161 		}
162 		udelay(1);
163 	}
164 
165 #ifdef CONFIG_CB710_DEBUG
166 	x = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
167 
168 	limit = 2000000 - limit;
169 	if (limit > 100)
170 		dev_dbg(cb710_slot_dev(slot),
171 			"WAIT10: waited %d loops, what %d, entry val %08X, exit val %08X\n",
172 			limit, what, e, x);
173 #endif
174 	return err < 0 ? err : 0;
175 }
176 
177 
178 static int cb710_wait_while_busy(struct cb710_slot *slot, uint8_t mask)
179 {
180 	unsigned limit = 500000;	/* FIXME: real timeout */
181 	int err = 0;
182 
183 #ifdef CONFIG_CB710_DEBUG
184 	u32 e, x;
185 	e = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
186 #endif
187 
188 	while (cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT) & mask) {
189 		if (!--limit) {
190 			cb710_dump_regs(cb710_slot_to_chip(slot),
191 				CB710_DUMP_REGS_MMC);
192 			err = -ETIMEDOUT;
193 			break;
194 		}
195 		udelay(1);
196 	}
197 
198 #ifdef CONFIG_CB710_DEBUG
199 	x = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
200 
201 	limit = 500000 - limit;
202 	if (limit > 100)
203 		dev_dbg(cb710_slot_dev(slot),
204 			"WAIT12: waited %d loops, mask %02X, entry val %08X, exit val %08X\n",
205 			limit, mask, e, x);
206 #endif
207 	return err;
208 }
209 
210 static void cb710_mmc_set_transfer_size(struct cb710_slot *slot,
211 	size_t count, size_t blocksize)
212 {
213 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
214 	cb710_write_port_32(slot, CB710_MMC_TRANSFER_SIZE_PORT,
215 		((count - 1) << 16)|(blocksize - 1));
216 
217 	dev_vdbg(cb710_slot_dev(slot), "set up for %zu block%s of %zu bytes\n",
218 		count, count == 1 ? "" : "s", blocksize);
219 }
220 
221 static void cb710_mmc_fifo_hack(struct cb710_slot *slot)
222 {
223 	/* without this, received data is prepended with 8-bytes of zeroes */
224 	u32 r1, r2;
225 	int ok = 0;
226 
227 	r1 = cb710_read_port_32(slot, CB710_MMC_DATA_PORT);
228 	r2 = cb710_read_port_32(slot, CB710_MMC_DATA_PORT);
229 	if (cb710_read_port_8(slot, CB710_MMC_STATUS0_PORT)
230 	    & CB710_MMC_S0_FIFO_UNDERFLOW) {
231 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT,
232 			CB710_MMC_S0_FIFO_UNDERFLOW);
233 		ok = 1;
234 	}
235 
236 	dev_dbg(cb710_slot_dev(slot),
237 		"FIFO-read-hack: expected STATUS0 bit was %s\n",
238 		ok ? "set." : "NOT SET!");
239 	dev_dbg(cb710_slot_dev(slot),
240 		"FIFO-read-hack: dwords ignored: %08X %08X - %s\n",
241 		r1, r2, (r1|r2) ? "BAD (NOT ZERO)!" : "ok");
242 }
243 
244 static int cb710_mmc_receive_pio(struct cb710_slot *slot,
245 	struct sg_mapping_iter *miter, size_t dw_count)
246 {
247 	if (!(cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT) & CB710_MMC_S2_FIFO_READY)) {
248 		int err = cb710_wait_for_event(slot,
249 			CB710_MMC_S1_PIO_TRANSFER_DONE);
250 		if (err)
251 			return err;
252 	}
253 
254 	cb710_sg_dwiter_write_from_io(miter,
255 		slot->iobase + CB710_MMC_DATA_PORT, dw_count);
256 
257 	return 0;
258 }
259 
260 static bool cb710_is_transfer_size_supported(struct mmc_data *data)
261 {
262 	return !(data->blksz & 15 && (data->blocks != 1 || data->blksz != 8));
263 }
264 
265 static int cb710_mmc_receive(struct cb710_slot *slot, struct mmc_data *data)
266 {
267 	struct sg_mapping_iter miter;
268 	size_t len, blocks = data->blocks;
269 	int err = 0;
270 
271 	/* TODO: I don't know how/if the hardware handles non-16B-boundary blocks
272 	 * except single 8B block */
273 	if (unlikely(data->blksz & 15 && (data->blocks != 1 || data->blksz != 8)))
274 		return -EINVAL;
275 
276 	sg_miter_start(&miter, data->sg, data->sg_len, SG_MITER_TO_SG);
277 
278 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
279 		15, CB710_MMC_C2_READ_PIO_SIZE_MASK);
280 
281 	cb710_mmc_fifo_hack(slot);
282 
283 	while (blocks-- > 0) {
284 		len = data->blksz;
285 
286 		while (len >= 16) {
287 			err = cb710_mmc_receive_pio(slot, &miter, 4);
288 			if (err)
289 				goto out;
290 			len -= 16;
291 		}
292 
293 		if (!len)
294 			continue;
295 
296 		cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
297 			len - 1, CB710_MMC_C2_READ_PIO_SIZE_MASK);
298 
299 		len = (len >= 8) ? 4 : 2;
300 		err = cb710_mmc_receive_pio(slot, &miter, len);
301 		if (err)
302 			goto out;
303 	}
304 out:
305 	sg_miter_stop(&miter);
306 	return err;
307 }
308 
309 static int cb710_mmc_send(struct cb710_slot *slot, struct mmc_data *data)
310 {
311 	struct sg_mapping_iter miter;
312 	size_t len, blocks = data->blocks;
313 	int err = 0;
314 
315 	/* TODO: I don't know how/if the hardware handles multiple
316 	 * non-16B-boundary blocks */
317 	if (unlikely(data->blocks > 1 && data->blksz & 15))
318 		return -EINVAL;
319 
320 	sg_miter_start(&miter, data->sg, data->sg_len, SG_MITER_FROM_SG);
321 
322 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
323 		0, CB710_MMC_C2_READ_PIO_SIZE_MASK);
324 
325 	while (blocks-- > 0) {
326 		len = (data->blksz + 15) >> 4;
327 		do {
328 			if (!(cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT)
329 			    & CB710_MMC_S2_FIFO_EMPTY)) {
330 				err = cb710_wait_for_event(slot,
331 					CB710_MMC_S1_PIO_TRANSFER_DONE);
332 				if (err)
333 					goto out;
334 			}
335 			cb710_sg_dwiter_read_to_io(&miter,
336 				slot->iobase + CB710_MMC_DATA_PORT, 4);
337 		} while (--len);
338 	}
339 out:
340 	sg_miter_stop(&miter);
341 	return err;
342 }
343 
344 static u16 cb710_encode_cmd_flags(struct cb710_mmc_reader *reader,
345 	struct mmc_command *cmd)
346 {
347 	unsigned int flags = cmd->flags;
348 	u16 cb_flags = 0;
349 
350 	/* Windows driver returned 0 for commands for which no response
351 	 * is expected. It happened that there were only two such commands
352 	 * used: MMC_GO_IDLE_STATE and MMC_GO_INACTIVE_STATE so it might
353 	 * as well be a bug in that driver.
354 	 *
355 	 * Original driver set bit 14 for MMC/SD application
356 	 * commands. There's no difference 'on the wire' and
357 	 * it apparently works without it anyway.
358 	 */
359 
360 	switch (flags & MMC_CMD_MASK) {
361 	case MMC_CMD_AC:	cb_flags = CB710_MMC_CMD_AC;	break;
362 	case MMC_CMD_ADTC:	cb_flags = CB710_MMC_CMD_ADTC;	break;
363 	case MMC_CMD_BC:	cb_flags = CB710_MMC_CMD_BC;	break;
364 	case MMC_CMD_BCR:	cb_flags = CB710_MMC_CMD_BCR;	break;
365 	}
366 
367 	if (flags & MMC_RSP_BUSY)
368 		cb_flags |= CB710_MMC_RSP_BUSY;
369 
370 	cb_flags |= cmd->opcode << CB710_MMC_CMD_CODE_SHIFT;
371 
372 	if (cmd->data && (cmd->data->flags & MMC_DATA_READ))
373 		cb_flags |= CB710_MMC_DATA_READ;
374 
375 	if (flags & MMC_RSP_PRESENT) {
376 		/* Windows driver set 01 at bits 4,3 except for
377 		 * MMC_SET_BLOCKLEN where it set 10. Maybe the
378 		 * hardware can do something special about this
379 		 * command? The original driver looks buggy/incomplete
380 		 * anyway so we ignore this for now.
381 		 *
382 		 * I assume that 00 here means no response is expected.
383 		 */
384 		cb_flags |= CB710_MMC_RSP_PRESENT;
385 
386 		if (flags & MMC_RSP_136)
387 			cb_flags |= CB710_MMC_RSP_136;
388 		if (!(flags & MMC_RSP_CRC))
389 			cb_flags |= CB710_MMC_RSP_NO_CRC;
390 	}
391 
392 	return cb_flags;
393 }
394 
395 static void cb710_receive_response(struct cb710_slot *slot,
396 	struct mmc_command *cmd)
397 {
398 	unsigned rsp_opcode, wanted_opcode;
399 
400 	/* Looks like final byte with CRC is always stripped (same as SDHCI) */
401 	if (cmd->flags & MMC_RSP_136) {
402 		u32 resp[4];
403 
404 		resp[0] = cb710_read_port_32(slot, CB710_MMC_RESPONSE3_PORT);
405 		resp[1] = cb710_read_port_32(slot, CB710_MMC_RESPONSE2_PORT);
406 		resp[2] = cb710_read_port_32(slot, CB710_MMC_RESPONSE1_PORT);
407 		resp[3] = cb710_read_port_32(slot, CB710_MMC_RESPONSE0_PORT);
408 		rsp_opcode = resp[0] >> 24;
409 
410 		cmd->resp[0] = (resp[0] << 8)|(resp[1] >> 24);
411 		cmd->resp[1] = (resp[1] << 8)|(resp[2] >> 24);
412 		cmd->resp[2] = (resp[2] << 8)|(resp[3] >> 24);
413 		cmd->resp[3] = (resp[3] << 8);
414 	} else {
415 		rsp_opcode = cb710_read_port_32(slot, CB710_MMC_RESPONSE1_PORT) & 0x3F;
416 		cmd->resp[0] = cb710_read_port_32(slot, CB710_MMC_RESPONSE0_PORT);
417 	}
418 
419 	wanted_opcode = (cmd->flags & MMC_RSP_OPCODE) ? cmd->opcode : 0x3F;
420 	if (rsp_opcode != wanted_opcode)
421 		cmd->error = -EILSEQ;
422 }
423 
424 static int cb710_mmc_transfer_data(struct cb710_slot *slot,
425 	struct mmc_data *data)
426 {
427 	int error, to;
428 
429 	if (data->flags & MMC_DATA_READ)
430 		error = cb710_mmc_receive(slot, data);
431 	else
432 		error = cb710_mmc_send(slot, data);
433 
434 	to = cb710_wait_for_event(slot, CB710_MMC_S1_DATA_TRANSFER_DONE);
435 	if (!error)
436 		error = to;
437 
438 	if (!error)
439 		data->bytes_xfered = data->blksz * data->blocks;
440 	return error;
441 }
442 
443 static int cb710_mmc_command(struct mmc_host *mmc, struct mmc_command *cmd)
444 {
445 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
446 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
447 	struct mmc_data *data = cmd->data;
448 
449 	u16 cb_cmd = cb710_encode_cmd_flags(reader, cmd);
450 	dev_dbg(cb710_slot_dev(slot), "cmd request: 0x%04X\n", cb_cmd);
451 
452 	if (data) {
453 		if (!cb710_is_transfer_size_supported(data)) {
454 			data->error = -EINVAL;
455 			return -1;
456 		}
457 		cb710_mmc_set_transfer_size(slot, data->blocks, data->blksz);
458 	}
459 
460 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20|CB710_MMC_S2_BUSY_10);
461 	cb710_write_port_16(slot, CB710_MMC_CMD_TYPE_PORT, cb_cmd);
462 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
463 	cb710_write_port_32(slot, CB710_MMC_CMD_PARAM_PORT, cmd->arg);
464 	cb710_mmc_reset_events(slot);
465 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
466 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x01, 0);
467 
468 	cmd->error = cb710_wait_for_event(slot, CB710_MMC_S1_COMMAND_SENT);
469 	if (cmd->error)
470 		return -1;
471 
472 	if (cmd->flags & MMC_RSP_PRESENT) {
473 		cb710_receive_response(slot, cmd);
474 		if (cmd->error)
475 			return -1;
476 	}
477 
478 	if (data)
479 		data->error = cb710_mmc_transfer_data(slot, data);
480 	return 0;
481 }
482 
483 static void cb710_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
484 {
485 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
486 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
487 
488 	WARN_ON(reader->mrq != NULL);
489 
490 	reader->mrq = mrq;
491 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_TEST_MASK, 0);
492 
493 	if (!cb710_mmc_command(mmc, mrq->cmd) && mrq->stop)
494 		cb710_mmc_command(mmc, mrq->stop);
495 
496 	tasklet_schedule(&reader->finish_req_tasklet);
497 }
498 
499 static int cb710_mmc_powerup(struct cb710_slot *slot)
500 {
501 #ifdef CONFIG_CB710_DEBUG
502 	struct cb710_chip *chip = cb710_slot_to_chip(slot);
503 #endif
504 	int err;
505 
506 	/* a lot of magic for now */
507 	dev_dbg(cb710_slot_dev(slot), "bus powerup\n");
508 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
509 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
510 	if (unlikely(err))
511 		return err;
512 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x80, 0);
513 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0x80, 0);
514 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
515 	mdelay(1);
516 	dev_dbg(cb710_slot_dev(slot), "after delay 1\n");
517 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
518 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
519 	if (unlikely(err))
520 		return err;
521 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x09, 0);
522 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
523 	mdelay(1);
524 	dev_dbg(cb710_slot_dev(slot), "after delay 2\n");
525 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
526 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
527 	if (unlikely(err))
528 		return err;
529 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0, 0x08);
530 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
531 	mdelay(2);
532 	dev_dbg(cb710_slot_dev(slot), "after delay 3\n");
533 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
534 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x06, 0);
535 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x70, 0);
536 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT, 0x80, 0);
537 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0x03, 0);
538 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
539 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
540 	if (unlikely(err))
541 		return err;
542 	/* This port behaves weird: quick byte reads of 0x08,0x09 return
543 	 * 0xFF,0x00 after writing 0xFFFF to 0x08; it works correctly when
544 	 * read/written from userspace...  What am I missing here?
545 	 * (it doesn't depend on write-to-read delay) */
546 	cb710_write_port_16(slot, CB710_MMC_CONFIGB_PORT, 0xFFFF);
547 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x06, 0);
548 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
549 	dev_dbg(cb710_slot_dev(slot), "bus powerup finished\n");
550 
551 	return cb710_check_event(slot, 0);
552 }
553 
554 static void cb710_mmc_powerdown(struct cb710_slot *slot)
555 {
556 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0, 0x81);
557 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0, 0x80);
558 }
559 
560 static void cb710_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
561 {
562 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
563 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
564 	int err;
565 
566 	cb710_mmc_select_clock_divider(mmc, ios->clock);
567 
568 	if (ios->power_mode != reader->last_power_mode) {
569 		switch (ios->power_mode) {
570 		case MMC_POWER_ON:
571 			err = cb710_mmc_powerup(slot);
572 			if (err) {
573 				dev_warn(cb710_slot_dev(slot),
574 					"powerup failed (%d)- retrying\n", err);
575 				cb710_mmc_powerdown(slot);
576 				udelay(1);
577 				err = cb710_mmc_powerup(slot);
578 				if (err)
579 					dev_warn(cb710_slot_dev(slot),
580 						"powerup retry failed (%d) - expect errors\n",
581 					err);
582 			}
583 			reader->last_power_mode = MMC_POWER_ON;
584 			break;
585 		case MMC_POWER_OFF:
586 			cb710_mmc_powerdown(slot);
587 			reader->last_power_mode = MMC_POWER_OFF;
588 			break;
589 		case MMC_POWER_UP:
590 		default:
591 			/* ignore */
592 			break;
593 		}
594 	}
595 
596 	cb710_mmc_enable_4bit_data(slot, ios->bus_width != MMC_BUS_WIDTH_1);
597 
598 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_TEST_MASK, 0);
599 }
600 
601 static int cb710_mmc_get_ro(struct mmc_host *mmc)
602 {
603 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
604 
605 	return cb710_read_port_8(slot, CB710_MMC_STATUS3_PORT)
606 		& CB710_MMC_S3_WRITE_PROTECTED;
607 }
608 
609 static int cb710_mmc_get_cd(struct mmc_host *mmc)
610 {
611 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
612 
613 	return cb710_read_port_8(slot, CB710_MMC_STATUS3_PORT)
614 		& CB710_MMC_S3_CARD_DETECTED;
615 }
616 
617 static int cb710_mmc_irq_handler(struct cb710_slot *slot)
618 {
619 	struct mmc_host *mmc = cb710_slot_to_mmc(slot);
620 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
621 	u32 status, config1, config2, irqen;
622 
623 	status = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
624 	irqen = cb710_read_port_32(slot, CB710_MMC_IRQ_ENABLE_PORT);
625 	config2 = cb710_read_port_32(slot, CB710_MMC_CONFIGB_PORT);
626 	config1 = cb710_read_port_32(slot, CB710_MMC_CONFIG_PORT);
627 
628 	dev_dbg(cb710_slot_dev(slot), "interrupt; status: %08X, "
629 		"ie: %08X, c2: %08X, c1: %08X\n",
630 		status, irqen, config2, config1);
631 
632 	if (status & (CB710_MMC_S1_CARD_CHANGED << 8)) {
633 		/* ack the event */
634 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT,
635 			CB710_MMC_S1_CARD_CHANGED);
636 		if ((irqen & CB710_MMC_IE_CISTATUS_MASK)
637 		    == CB710_MMC_IE_CISTATUS_MASK)
638 			mmc_detect_change(mmc, HZ/5);
639 	} else {
640 		dev_dbg(cb710_slot_dev(slot), "unknown interrupt (test)\n");
641 		spin_lock(&reader->irq_lock);
642 		__cb710_mmc_enable_irq(slot, 0, CB710_MMC_IE_TEST_MASK);
643 		spin_unlock(&reader->irq_lock);
644 	}
645 
646 	return 1;
647 }
648 
649 static void cb710_mmc_finish_request_tasklet(unsigned long data)
650 {
651 	struct mmc_host *mmc = (void *)data;
652 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
653 	struct mmc_request *mrq = reader->mrq;
654 
655 	reader->mrq = NULL;
656 	mmc_request_done(mmc, mrq);
657 }
658 
659 static const struct mmc_host_ops cb710_mmc_host = {
660 	.request = cb710_mmc_request,
661 	.set_ios = cb710_mmc_set_ios,
662 	.get_ro = cb710_mmc_get_ro,
663 	.get_cd = cb710_mmc_get_cd,
664 };
665 
666 #ifdef CONFIG_PM
667 
668 static int cb710_mmc_suspend(struct platform_device *pdev, pm_message_t state)
669 {
670 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
671 
672 	cb710_mmc_enable_irq(slot, 0, ~0);
673 	return 0;
674 }
675 
676 static int cb710_mmc_resume(struct platform_device *pdev)
677 {
678 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
679 
680 	cb710_mmc_enable_irq(slot, 0, ~0);
681 	return 0;
682 }
683 
684 #endif /* CONFIG_PM */
685 
686 static int cb710_mmc_init(struct platform_device *pdev)
687 {
688 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
689 	struct cb710_chip *chip = cb710_slot_to_chip(slot);
690 	struct mmc_host *mmc;
691 	struct cb710_mmc_reader *reader;
692 	int err;
693 	u32 val;
694 
695 	mmc = mmc_alloc_host(sizeof(*reader), cb710_slot_dev(slot));
696 	if (!mmc)
697 		return -ENOMEM;
698 
699 	platform_set_drvdata(pdev, mmc);
700 
701 	/* harmless (maybe) magic */
702 	pci_read_config_dword(chip->pdev, 0x48, &val);
703 	val = cb710_src_freq_mhz[(val >> 16) & 0xF];
704 	dev_dbg(cb710_slot_dev(slot), "source frequency: %dMHz\n", val);
705 	val *= 1000000;
706 
707 	mmc->ops = &cb710_mmc_host;
708 	mmc->f_max = val;
709 	mmc->f_min = val >> cb710_clock_divider_log2[CB710_MAX_DIVIDER_IDX];
710 	mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34;
711 	mmc->caps = MMC_CAP_4_BIT_DATA;
712 	/*
713 	 * In cb710_wait_for_event() we use a fixed timeout of ~2s, hence let's
714 	 * inform the core about it. A future improvement should instead make
715 	 * use of the cmd->busy_timeout.
716 	 */
717 	mmc->max_busy_timeout = CB710_MMC_REQ_TIMEOUT_MS;
718 
719 	reader = mmc_priv(mmc);
720 
721 	tasklet_init(&reader->finish_req_tasklet,
722 		cb710_mmc_finish_request_tasklet, (unsigned long)mmc);
723 	spin_lock_init(&reader->irq_lock);
724 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
725 
726 	cb710_mmc_enable_irq(slot, 0, ~0);
727 	cb710_set_irq_handler(slot, cb710_mmc_irq_handler);
728 
729 	err = mmc_add_host(mmc);
730 	if (unlikely(err))
731 		goto err_free_mmc;
732 
733 	dev_dbg(cb710_slot_dev(slot), "mmc_hostname is %s\n",
734 		mmc_hostname(mmc));
735 
736 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_CARD_INSERTION_STATUS, 0);
737 
738 	return 0;
739 
740 err_free_mmc:
741 	dev_dbg(cb710_slot_dev(slot), "mmc_add_host() failed: %d\n", err);
742 
743 	cb710_set_irq_handler(slot, NULL);
744 	mmc_free_host(mmc);
745 	return err;
746 }
747 
748 static int cb710_mmc_exit(struct platform_device *pdev)
749 {
750 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
751 	struct mmc_host *mmc = cb710_slot_to_mmc(slot);
752 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
753 
754 	cb710_mmc_enable_irq(slot, 0, CB710_MMC_IE_CARD_INSERTION_STATUS);
755 
756 	mmc_remove_host(mmc);
757 
758 	/* IRQs should be disabled now, but let's stay on the safe side */
759 	cb710_mmc_enable_irq(slot, 0, ~0);
760 	cb710_set_irq_handler(slot, NULL);
761 
762 	/* clear config ports - just in case */
763 	cb710_write_port_32(slot, CB710_MMC_CONFIG_PORT, 0);
764 	cb710_write_port_16(slot, CB710_MMC_CONFIGB_PORT, 0);
765 
766 	tasklet_kill(&reader->finish_req_tasklet);
767 
768 	mmc_free_host(mmc);
769 	return 0;
770 }
771 
772 static struct platform_driver cb710_mmc_driver = {
773 	.driver.name = "cb710-mmc",
774 	.probe = cb710_mmc_init,
775 	.remove = cb710_mmc_exit,
776 #ifdef CONFIG_PM
777 	.suspend = cb710_mmc_suspend,
778 	.resume = cb710_mmc_resume,
779 #endif
780 };
781 
782 module_platform_driver(cb710_mmc_driver);
783 
784 MODULE_AUTHOR("Michał Mirosław <mirq-linux@rere.qmqm.pl>");
785 MODULE_DESCRIPTION("ENE CB710 memory card reader driver - MMC/SD part");
786 MODULE_LICENSE("GPL");
787 MODULE_ALIAS("platform:cb710-mmc");
788