xref: /openbmc/linux/drivers/mmc/host/cb710-mmc.c (revision e3b9f1e8)
1 /*
2  *  cb710/mmc.c
3  *
4  *  Copyright by Michał Mirosław, 2008-2009
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/pci.h>
13 #include <linux/delay.h>
14 #include "cb710-mmc.h"
15 
16 static const u8 cb710_clock_divider_log2[8] = {
17 /*	1, 2, 4, 8, 16, 32, 128, 512 */
18 	0, 1, 2, 3,  4,  5,   7,   9
19 };
20 #define CB710_MAX_DIVIDER_IDX	\
21 	(ARRAY_SIZE(cb710_clock_divider_log2) - 1)
22 
23 static const u8 cb710_src_freq_mhz[16] = {
24 	33, 10, 20, 25, 30, 35, 40, 45,
25 	50, 55, 60, 65, 70, 75, 80, 85
26 };
27 
28 static void cb710_mmc_select_clock_divider(struct mmc_host *mmc, int hz)
29 {
30 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
31 	struct pci_dev *pdev = cb710_slot_to_chip(slot)->pdev;
32 	u32 src_freq_idx;
33 	u32 divider_idx;
34 	int src_hz;
35 
36 	/* on CB710 in HP nx9500:
37 	 *   src_freq_idx == 0
38 	 *   indexes 1-7 work as written in the table
39 	 *   indexes 0,8-15 give no clock output
40 	 */
41 	pci_read_config_dword(pdev, 0x48, &src_freq_idx);
42 	src_freq_idx = (src_freq_idx >> 16) & 0xF;
43 	src_hz = cb710_src_freq_mhz[src_freq_idx] * 1000000;
44 
45 	for (divider_idx = 0; divider_idx < CB710_MAX_DIVIDER_IDX; ++divider_idx) {
46 		if (hz >= src_hz >> cb710_clock_divider_log2[divider_idx])
47 			break;
48 	}
49 
50 	if (src_freq_idx)
51 		divider_idx |= 0x8;
52 	else if (divider_idx == 0)
53 		divider_idx = 1;
54 
55 	cb710_pci_update_config_reg(pdev, 0x40, ~0xF0000000, divider_idx << 28);
56 
57 	dev_dbg(cb710_slot_dev(slot),
58 		"clock set to %d Hz, wanted %d Hz; src_freq_idx = %d, divider_idx = %d|%d\n",
59 		src_hz >> cb710_clock_divider_log2[divider_idx & 7],
60 		hz, src_freq_idx, divider_idx & 7, divider_idx & 8);
61 }
62 
63 static void __cb710_mmc_enable_irq(struct cb710_slot *slot,
64 	unsigned short enable, unsigned short mask)
65 {
66 	/* clear global IE
67 	 * - it gets set later if any interrupt sources are enabled */
68 	mask |= CB710_MMC_IE_IRQ_ENABLE;
69 
70 	/* look like interrupt is fired whenever
71 	 * WORD[0x0C] & WORD[0x10] != 0;
72 	 * -> bit 15 port 0x0C seems to be global interrupt enable
73 	 */
74 
75 	enable = (cb710_read_port_16(slot, CB710_MMC_IRQ_ENABLE_PORT)
76 		& ~mask) | enable;
77 
78 	if (enable)
79 		enable |= CB710_MMC_IE_IRQ_ENABLE;
80 
81 	cb710_write_port_16(slot, CB710_MMC_IRQ_ENABLE_PORT, enable);
82 }
83 
84 static void cb710_mmc_enable_irq(struct cb710_slot *slot,
85 	unsigned short enable, unsigned short mask)
86 {
87 	struct cb710_mmc_reader *reader = mmc_priv(cb710_slot_to_mmc(slot));
88 	unsigned long flags;
89 
90 	spin_lock_irqsave(&reader->irq_lock, flags);
91 	/* this is the only thing irq_lock protects */
92 	__cb710_mmc_enable_irq(slot, enable, mask);
93 	spin_unlock_irqrestore(&reader->irq_lock, flags);
94 }
95 
96 static void cb710_mmc_reset_events(struct cb710_slot *slot)
97 {
98 	cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT, 0xFF);
99 	cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT, 0xFF);
100 	cb710_write_port_8(slot, CB710_MMC_STATUS2_PORT, 0xFF);
101 }
102 
103 static void cb710_mmc_enable_4bit_data(struct cb710_slot *slot, int enable)
104 {
105 	if (enable)
106 		cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT,
107 			CB710_MMC_C1_4BIT_DATA_BUS, 0);
108 	else
109 		cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT,
110 			0, CB710_MMC_C1_4BIT_DATA_BUS);
111 }
112 
113 static int cb710_check_event(struct cb710_slot *slot, u8 what)
114 {
115 	u16 status;
116 
117 	status = cb710_read_port_16(slot, CB710_MMC_STATUS_PORT);
118 
119 	if (status & CB710_MMC_S0_FIFO_UNDERFLOW) {
120 		/* it is just a guess, so log it */
121 		dev_dbg(cb710_slot_dev(slot),
122 			"CHECK : ignoring bit 6 in status %04X\n", status);
123 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT,
124 			CB710_MMC_S0_FIFO_UNDERFLOW);
125 		status &= ~CB710_MMC_S0_FIFO_UNDERFLOW;
126 	}
127 
128 	if (status & CB710_MMC_STATUS_ERROR_EVENTS) {
129 		dev_dbg(cb710_slot_dev(slot),
130 			"CHECK : returning EIO on status %04X\n", status);
131 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT, status & 0xFF);
132 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT,
133 			CB710_MMC_S1_RESET);
134 		return -EIO;
135 	}
136 
137 	/* 'what' is a bit in MMC_STATUS1 */
138 	if ((status >> 8) & what) {
139 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT, what);
140 		return 1;
141 	}
142 
143 	return 0;
144 }
145 
146 static int cb710_wait_for_event(struct cb710_slot *slot, u8 what)
147 {
148 	int err = 0;
149 	unsigned limit = 2000000;	/* FIXME: real timeout */
150 
151 #ifdef CONFIG_CB710_DEBUG
152 	u32 e, x;
153 	e = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
154 #endif
155 
156 	while (!(err = cb710_check_event(slot, what))) {
157 		if (!--limit) {
158 			cb710_dump_regs(cb710_slot_to_chip(slot),
159 				CB710_DUMP_REGS_MMC);
160 			err = -ETIMEDOUT;
161 			break;
162 		}
163 		udelay(1);
164 	}
165 
166 #ifdef CONFIG_CB710_DEBUG
167 	x = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
168 
169 	limit = 2000000 - limit;
170 	if (limit > 100)
171 		dev_dbg(cb710_slot_dev(slot),
172 			"WAIT10: waited %d loops, what %d, entry val %08X, exit val %08X\n",
173 			limit, what, e, x);
174 #endif
175 	return err < 0 ? err : 0;
176 }
177 
178 
179 static int cb710_wait_while_busy(struct cb710_slot *slot, uint8_t mask)
180 {
181 	unsigned limit = 500000;	/* FIXME: real timeout */
182 	int err = 0;
183 
184 #ifdef CONFIG_CB710_DEBUG
185 	u32 e, x;
186 	e = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
187 #endif
188 
189 	while (cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT) & mask) {
190 		if (!--limit) {
191 			cb710_dump_regs(cb710_slot_to_chip(slot),
192 				CB710_DUMP_REGS_MMC);
193 			err = -ETIMEDOUT;
194 			break;
195 		}
196 		udelay(1);
197 	}
198 
199 #ifdef CONFIG_CB710_DEBUG
200 	x = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
201 
202 	limit = 500000 - limit;
203 	if (limit > 100)
204 		dev_dbg(cb710_slot_dev(slot),
205 			"WAIT12: waited %d loops, mask %02X, entry val %08X, exit val %08X\n",
206 			limit, mask, e, x);
207 #endif
208 	return err;
209 }
210 
211 static void cb710_mmc_set_transfer_size(struct cb710_slot *slot,
212 	size_t count, size_t blocksize)
213 {
214 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
215 	cb710_write_port_32(slot, CB710_MMC_TRANSFER_SIZE_PORT,
216 		((count - 1) << 16)|(blocksize - 1));
217 
218 	dev_vdbg(cb710_slot_dev(slot), "set up for %zu block%s of %zu bytes\n",
219 		count, count == 1 ? "" : "s", blocksize);
220 }
221 
222 static void cb710_mmc_fifo_hack(struct cb710_slot *slot)
223 {
224 	/* without this, received data is prepended with 8-bytes of zeroes */
225 	u32 r1, r2;
226 	int ok = 0;
227 
228 	r1 = cb710_read_port_32(slot, CB710_MMC_DATA_PORT);
229 	r2 = cb710_read_port_32(slot, CB710_MMC_DATA_PORT);
230 	if (cb710_read_port_8(slot, CB710_MMC_STATUS0_PORT)
231 	    & CB710_MMC_S0_FIFO_UNDERFLOW) {
232 		cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT,
233 			CB710_MMC_S0_FIFO_UNDERFLOW);
234 		ok = 1;
235 	}
236 
237 	dev_dbg(cb710_slot_dev(slot),
238 		"FIFO-read-hack: expected STATUS0 bit was %s\n",
239 		ok ? "set." : "NOT SET!");
240 	dev_dbg(cb710_slot_dev(slot),
241 		"FIFO-read-hack: dwords ignored: %08X %08X - %s\n",
242 		r1, r2, (r1|r2) ? "BAD (NOT ZERO)!" : "ok");
243 }
244 
245 static int cb710_mmc_receive_pio(struct cb710_slot *slot,
246 	struct sg_mapping_iter *miter, size_t dw_count)
247 {
248 	if (!(cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT) & CB710_MMC_S2_FIFO_READY)) {
249 		int err = cb710_wait_for_event(slot,
250 			CB710_MMC_S1_PIO_TRANSFER_DONE);
251 		if (err)
252 			return err;
253 	}
254 
255 	cb710_sg_dwiter_write_from_io(miter,
256 		slot->iobase + CB710_MMC_DATA_PORT, dw_count);
257 
258 	return 0;
259 }
260 
261 static bool cb710_is_transfer_size_supported(struct mmc_data *data)
262 {
263 	return !(data->blksz & 15 && (data->blocks != 1 || data->blksz != 8));
264 }
265 
266 static int cb710_mmc_receive(struct cb710_slot *slot, struct mmc_data *data)
267 {
268 	struct sg_mapping_iter miter;
269 	size_t len, blocks = data->blocks;
270 	int err = 0;
271 
272 	/* TODO: I don't know how/if the hardware handles non-16B-boundary blocks
273 	 * except single 8B block */
274 	if (unlikely(data->blksz & 15 && (data->blocks != 1 || data->blksz != 8)))
275 		return -EINVAL;
276 
277 	sg_miter_start(&miter, data->sg, data->sg_len, SG_MITER_TO_SG);
278 
279 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
280 		15, CB710_MMC_C2_READ_PIO_SIZE_MASK);
281 
282 	cb710_mmc_fifo_hack(slot);
283 
284 	while (blocks-- > 0) {
285 		len = data->blksz;
286 
287 		while (len >= 16) {
288 			err = cb710_mmc_receive_pio(slot, &miter, 4);
289 			if (err)
290 				goto out;
291 			len -= 16;
292 		}
293 
294 		if (!len)
295 			continue;
296 
297 		cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
298 			len - 1, CB710_MMC_C2_READ_PIO_SIZE_MASK);
299 
300 		len = (len >= 8) ? 4 : 2;
301 		err = cb710_mmc_receive_pio(slot, &miter, len);
302 		if (err)
303 			goto out;
304 	}
305 out:
306 	sg_miter_stop(&miter);
307 	return err;
308 }
309 
310 static int cb710_mmc_send(struct cb710_slot *slot, struct mmc_data *data)
311 {
312 	struct sg_mapping_iter miter;
313 	size_t len, blocks = data->blocks;
314 	int err = 0;
315 
316 	/* TODO: I don't know how/if the hardware handles multiple
317 	 * non-16B-boundary blocks */
318 	if (unlikely(data->blocks > 1 && data->blksz & 15))
319 		return -EINVAL;
320 
321 	sg_miter_start(&miter, data->sg, data->sg_len, SG_MITER_FROM_SG);
322 
323 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT,
324 		0, CB710_MMC_C2_READ_PIO_SIZE_MASK);
325 
326 	while (blocks-- > 0) {
327 		len = (data->blksz + 15) >> 4;
328 		do {
329 			if (!(cb710_read_port_8(slot, CB710_MMC_STATUS2_PORT)
330 			    & CB710_MMC_S2_FIFO_EMPTY)) {
331 				err = cb710_wait_for_event(slot,
332 					CB710_MMC_S1_PIO_TRANSFER_DONE);
333 				if (err)
334 					goto out;
335 			}
336 			cb710_sg_dwiter_read_to_io(&miter,
337 				slot->iobase + CB710_MMC_DATA_PORT, 4);
338 		} while (--len);
339 	}
340 out:
341 	sg_miter_stop(&miter);
342 	return err;
343 }
344 
345 static u16 cb710_encode_cmd_flags(struct cb710_mmc_reader *reader,
346 	struct mmc_command *cmd)
347 {
348 	unsigned int flags = cmd->flags;
349 	u16 cb_flags = 0;
350 
351 	/* Windows driver returned 0 for commands for which no response
352 	 * is expected. It happened that there were only two such commands
353 	 * used: MMC_GO_IDLE_STATE and MMC_GO_INACTIVE_STATE so it might
354 	 * as well be a bug in that driver.
355 	 *
356 	 * Original driver set bit 14 for MMC/SD application
357 	 * commands. There's no difference 'on the wire' and
358 	 * it apparently works without it anyway.
359 	 */
360 
361 	switch (flags & MMC_CMD_MASK) {
362 	case MMC_CMD_AC:	cb_flags = CB710_MMC_CMD_AC;	break;
363 	case MMC_CMD_ADTC:	cb_flags = CB710_MMC_CMD_ADTC;	break;
364 	case MMC_CMD_BC:	cb_flags = CB710_MMC_CMD_BC;	break;
365 	case MMC_CMD_BCR:	cb_flags = CB710_MMC_CMD_BCR;	break;
366 	}
367 
368 	if (flags & MMC_RSP_BUSY)
369 		cb_flags |= CB710_MMC_RSP_BUSY;
370 
371 	cb_flags |= cmd->opcode << CB710_MMC_CMD_CODE_SHIFT;
372 
373 	if (cmd->data && (cmd->data->flags & MMC_DATA_READ))
374 		cb_flags |= CB710_MMC_DATA_READ;
375 
376 	if (flags & MMC_RSP_PRESENT) {
377 		/* Windows driver set 01 at bits 4,3 except for
378 		 * MMC_SET_BLOCKLEN where it set 10. Maybe the
379 		 * hardware can do something special about this
380 		 * command? The original driver looks buggy/incomplete
381 		 * anyway so we ignore this for now.
382 		 *
383 		 * I assume that 00 here means no response is expected.
384 		 */
385 		cb_flags |= CB710_MMC_RSP_PRESENT;
386 
387 		if (flags & MMC_RSP_136)
388 			cb_flags |= CB710_MMC_RSP_136;
389 		if (!(flags & MMC_RSP_CRC))
390 			cb_flags |= CB710_MMC_RSP_NO_CRC;
391 	}
392 
393 	return cb_flags;
394 }
395 
396 static void cb710_receive_response(struct cb710_slot *slot,
397 	struct mmc_command *cmd)
398 {
399 	unsigned rsp_opcode, wanted_opcode;
400 
401 	/* Looks like final byte with CRC is always stripped (same as SDHCI) */
402 	if (cmd->flags & MMC_RSP_136) {
403 		u32 resp[4];
404 
405 		resp[0] = cb710_read_port_32(slot, CB710_MMC_RESPONSE3_PORT);
406 		resp[1] = cb710_read_port_32(slot, CB710_MMC_RESPONSE2_PORT);
407 		resp[2] = cb710_read_port_32(slot, CB710_MMC_RESPONSE1_PORT);
408 		resp[3] = cb710_read_port_32(slot, CB710_MMC_RESPONSE0_PORT);
409 		rsp_opcode = resp[0] >> 24;
410 
411 		cmd->resp[0] = (resp[0] << 8)|(resp[1] >> 24);
412 		cmd->resp[1] = (resp[1] << 8)|(resp[2] >> 24);
413 		cmd->resp[2] = (resp[2] << 8)|(resp[3] >> 24);
414 		cmd->resp[3] = (resp[3] << 8);
415 	} else {
416 		rsp_opcode = cb710_read_port_32(slot, CB710_MMC_RESPONSE1_PORT) & 0x3F;
417 		cmd->resp[0] = cb710_read_port_32(slot, CB710_MMC_RESPONSE0_PORT);
418 	}
419 
420 	wanted_opcode = (cmd->flags & MMC_RSP_OPCODE) ? cmd->opcode : 0x3F;
421 	if (rsp_opcode != wanted_opcode)
422 		cmd->error = -EILSEQ;
423 }
424 
425 static int cb710_mmc_transfer_data(struct cb710_slot *slot,
426 	struct mmc_data *data)
427 {
428 	int error, to;
429 
430 	if (data->flags & MMC_DATA_READ)
431 		error = cb710_mmc_receive(slot, data);
432 	else
433 		error = cb710_mmc_send(slot, data);
434 
435 	to = cb710_wait_for_event(slot, CB710_MMC_S1_DATA_TRANSFER_DONE);
436 	if (!error)
437 		error = to;
438 
439 	if (!error)
440 		data->bytes_xfered = data->blksz * data->blocks;
441 	return error;
442 }
443 
444 static int cb710_mmc_command(struct mmc_host *mmc, struct mmc_command *cmd)
445 {
446 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
447 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
448 	struct mmc_data *data = cmd->data;
449 
450 	u16 cb_cmd = cb710_encode_cmd_flags(reader, cmd);
451 	dev_dbg(cb710_slot_dev(slot), "cmd request: 0x%04X\n", cb_cmd);
452 
453 	if (data) {
454 		if (!cb710_is_transfer_size_supported(data)) {
455 			data->error = -EINVAL;
456 			return -1;
457 		}
458 		cb710_mmc_set_transfer_size(slot, data->blocks, data->blksz);
459 	}
460 
461 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20|CB710_MMC_S2_BUSY_10);
462 	cb710_write_port_16(slot, CB710_MMC_CMD_TYPE_PORT, cb_cmd);
463 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
464 	cb710_write_port_32(slot, CB710_MMC_CMD_PARAM_PORT, cmd->arg);
465 	cb710_mmc_reset_events(slot);
466 	cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
467 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x01, 0);
468 
469 	cmd->error = cb710_wait_for_event(slot, CB710_MMC_S1_COMMAND_SENT);
470 	if (cmd->error)
471 		return -1;
472 
473 	if (cmd->flags & MMC_RSP_PRESENT) {
474 		cb710_receive_response(slot, cmd);
475 		if (cmd->error)
476 			return -1;
477 	}
478 
479 	if (data)
480 		data->error = cb710_mmc_transfer_data(slot, data);
481 	return 0;
482 }
483 
484 static void cb710_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
485 {
486 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
487 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
488 
489 	WARN_ON(reader->mrq != NULL);
490 
491 	reader->mrq = mrq;
492 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_TEST_MASK, 0);
493 
494 	if (!cb710_mmc_command(mmc, mrq->cmd) && mrq->stop)
495 		cb710_mmc_command(mmc, mrq->stop);
496 
497 	tasklet_schedule(&reader->finish_req_tasklet);
498 }
499 
500 static int cb710_mmc_powerup(struct cb710_slot *slot)
501 {
502 #ifdef CONFIG_CB710_DEBUG
503 	struct cb710_chip *chip = cb710_slot_to_chip(slot);
504 #endif
505 	int err;
506 
507 	/* a lot of magic for now */
508 	dev_dbg(cb710_slot_dev(slot), "bus powerup\n");
509 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
510 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
511 	if (unlikely(err))
512 		return err;
513 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x80, 0);
514 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0x80, 0);
515 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
516 	mdelay(1);
517 	dev_dbg(cb710_slot_dev(slot), "after delay 1\n");
518 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
519 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
520 	if (unlikely(err))
521 		return err;
522 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x09, 0);
523 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
524 	mdelay(1);
525 	dev_dbg(cb710_slot_dev(slot), "after delay 2\n");
526 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
527 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
528 	if (unlikely(err))
529 		return err;
530 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0, 0x08);
531 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
532 	mdelay(2);
533 	dev_dbg(cb710_slot_dev(slot), "after delay 3\n");
534 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
535 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x06, 0);
536 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0x70, 0);
537 	cb710_modify_port_8(slot, CB710_MMC_CONFIG2_PORT, 0x80, 0);
538 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0x03, 0);
539 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
540 	err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20);
541 	if (unlikely(err))
542 		return err;
543 	/* This port behaves weird: quick byte reads of 0x08,0x09 return
544 	 * 0xFF,0x00 after writing 0xFFFF to 0x08; it works correctly when
545 	 * read/written from userspace...  What am I missing here?
546 	 * (it doesn't depend on write-to-read delay) */
547 	cb710_write_port_16(slot, CB710_MMC_CONFIGB_PORT, 0xFFFF);
548 	cb710_modify_port_8(slot, CB710_MMC_CONFIG0_PORT, 0x06, 0);
549 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
550 	dev_dbg(cb710_slot_dev(slot), "bus powerup finished\n");
551 
552 	return cb710_check_event(slot, 0);
553 }
554 
555 static void cb710_mmc_powerdown(struct cb710_slot *slot)
556 {
557 	cb710_modify_port_8(slot, CB710_MMC_CONFIG1_PORT, 0, 0x81);
558 	cb710_modify_port_8(slot, CB710_MMC_CONFIG3_PORT, 0, 0x80);
559 }
560 
561 static void cb710_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
562 {
563 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
564 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
565 	int err;
566 
567 	cb710_mmc_select_clock_divider(mmc, ios->clock);
568 
569 	if (ios->power_mode != reader->last_power_mode)
570 	switch (ios->power_mode) {
571 	case MMC_POWER_ON:
572 		err = cb710_mmc_powerup(slot);
573 		if (err) {
574 			dev_warn(cb710_slot_dev(slot),
575 				"powerup failed (%d)- retrying\n", err);
576 			cb710_mmc_powerdown(slot);
577 			udelay(1);
578 			err = cb710_mmc_powerup(slot);
579 			if (err)
580 				dev_warn(cb710_slot_dev(slot),
581 					"powerup retry failed (%d) - expect errors\n",
582 					err);
583 		}
584 		reader->last_power_mode = MMC_POWER_ON;
585 		break;
586 	case MMC_POWER_OFF:
587 		cb710_mmc_powerdown(slot);
588 		reader->last_power_mode = MMC_POWER_OFF;
589 		break;
590 	case MMC_POWER_UP:
591 	default:
592 		/* ignore */;
593 	}
594 
595 	cb710_mmc_enable_4bit_data(slot, ios->bus_width != MMC_BUS_WIDTH_1);
596 
597 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_TEST_MASK, 0);
598 }
599 
600 static int cb710_mmc_get_ro(struct mmc_host *mmc)
601 {
602 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
603 
604 	return cb710_read_port_8(slot, CB710_MMC_STATUS3_PORT)
605 		& CB710_MMC_S3_WRITE_PROTECTED;
606 }
607 
608 static int cb710_mmc_get_cd(struct mmc_host *mmc)
609 {
610 	struct cb710_slot *slot = cb710_mmc_to_slot(mmc);
611 
612 	return cb710_read_port_8(slot, CB710_MMC_STATUS3_PORT)
613 		& CB710_MMC_S3_CARD_DETECTED;
614 }
615 
616 static int cb710_mmc_irq_handler(struct cb710_slot *slot)
617 {
618 	struct mmc_host *mmc = cb710_slot_to_mmc(slot);
619 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
620 	u32 status, config1, config2, irqen;
621 
622 	status = cb710_read_port_32(slot, CB710_MMC_STATUS_PORT);
623 	irqen = cb710_read_port_32(slot, CB710_MMC_IRQ_ENABLE_PORT);
624 	config2 = cb710_read_port_32(slot, CB710_MMC_CONFIGB_PORT);
625 	config1 = cb710_read_port_32(slot, CB710_MMC_CONFIG_PORT);
626 
627 	dev_dbg(cb710_slot_dev(slot), "interrupt; status: %08X, "
628 		"ie: %08X, c2: %08X, c1: %08X\n",
629 		status, irqen, config2, config1);
630 
631 	if (status & (CB710_MMC_S1_CARD_CHANGED << 8)) {
632 		/* ack the event */
633 		cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT,
634 			CB710_MMC_S1_CARD_CHANGED);
635 		if ((irqen & CB710_MMC_IE_CISTATUS_MASK)
636 		    == CB710_MMC_IE_CISTATUS_MASK)
637 			mmc_detect_change(mmc, HZ/5);
638 	} else {
639 		dev_dbg(cb710_slot_dev(slot), "unknown interrupt (test)\n");
640 		spin_lock(&reader->irq_lock);
641 		__cb710_mmc_enable_irq(slot, 0, CB710_MMC_IE_TEST_MASK);
642 		spin_unlock(&reader->irq_lock);
643 	}
644 
645 	return 1;
646 }
647 
648 static void cb710_mmc_finish_request_tasklet(unsigned long data)
649 {
650 	struct mmc_host *mmc = (void *)data;
651 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
652 	struct mmc_request *mrq = reader->mrq;
653 
654 	reader->mrq = NULL;
655 	mmc_request_done(mmc, mrq);
656 }
657 
658 static const struct mmc_host_ops cb710_mmc_host = {
659 	.request = cb710_mmc_request,
660 	.set_ios = cb710_mmc_set_ios,
661 	.get_ro = cb710_mmc_get_ro,
662 	.get_cd = cb710_mmc_get_cd,
663 };
664 
665 #ifdef CONFIG_PM
666 
667 static int cb710_mmc_suspend(struct platform_device *pdev, pm_message_t state)
668 {
669 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
670 
671 	cb710_mmc_enable_irq(slot, 0, ~0);
672 	return 0;
673 }
674 
675 static int cb710_mmc_resume(struct platform_device *pdev)
676 {
677 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
678 
679 	cb710_mmc_enable_irq(slot, 0, ~0);
680 	return 0;
681 }
682 
683 #endif /* CONFIG_PM */
684 
685 static int cb710_mmc_init(struct platform_device *pdev)
686 {
687 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
688 	struct cb710_chip *chip = cb710_slot_to_chip(slot);
689 	struct mmc_host *mmc;
690 	struct cb710_mmc_reader *reader;
691 	int err;
692 	u32 val;
693 
694 	mmc = mmc_alloc_host(sizeof(*reader), cb710_slot_dev(slot));
695 	if (!mmc)
696 		return -ENOMEM;
697 
698 	platform_set_drvdata(pdev, mmc);
699 
700 	/* harmless (maybe) magic */
701 	pci_read_config_dword(chip->pdev, 0x48, &val);
702 	val = cb710_src_freq_mhz[(val >> 16) & 0xF];
703 	dev_dbg(cb710_slot_dev(slot), "source frequency: %dMHz\n", val);
704 	val *= 1000000;
705 
706 	mmc->ops = &cb710_mmc_host;
707 	mmc->f_max = val;
708 	mmc->f_min = val >> cb710_clock_divider_log2[CB710_MAX_DIVIDER_IDX];
709 	mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34;
710 	mmc->caps = MMC_CAP_4_BIT_DATA;
711 
712 	reader = mmc_priv(mmc);
713 
714 	tasklet_init(&reader->finish_req_tasklet,
715 		cb710_mmc_finish_request_tasklet, (unsigned long)mmc);
716 	spin_lock_init(&reader->irq_lock);
717 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
718 
719 	cb710_mmc_enable_irq(slot, 0, ~0);
720 	cb710_set_irq_handler(slot, cb710_mmc_irq_handler);
721 
722 	err = mmc_add_host(mmc);
723 	if (unlikely(err))
724 		goto err_free_mmc;
725 
726 	dev_dbg(cb710_slot_dev(slot), "mmc_hostname is %s\n",
727 		mmc_hostname(mmc));
728 
729 	cb710_mmc_enable_irq(slot, CB710_MMC_IE_CARD_INSERTION_STATUS, 0);
730 
731 	return 0;
732 
733 err_free_mmc:
734 	dev_dbg(cb710_slot_dev(slot), "mmc_add_host() failed: %d\n", err);
735 
736 	cb710_set_irq_handler(slot, NULL);
737 	mmc_free_host(mmc);
738 	return err;
739 }
740 
741 static int cb710_mmc_exit(struct platform_device *pdev)
742 {
743 	struct cb710_slot *slot = cb710_pdev_to_slot(pdev);
744 	struct mmc_host *mmc = cb710_slot_to_mmc(slot);
745 	struct cb710_mmc_reader *reader = mmc_priv(mmc);
746 
747 	cb710_mmc_enable_irq(slot, 0, CB710_MMC_IE_CARD_INSERTION_STATUS);
748 
749 	mmc_remove_host(mmc);
750 
751 	/* IRQs should be disabled now, but let's stay on the safe side */
752 	cb710_mmc_enable_irq(slot, 0, ~0);
753 	cb710_set_irq_handler(slot, NULL);
754 
755 	/* clear config ports - just in case */
756 	cb710_write_port_32(slot, CB710_MMC_CONFIG_PORT, 0);
757 	cb710_write_port_16(slot, CB710_MMC_CONFIGB_PORT, 0);
758 
759 	tasklet_kill(&reader->finish_req_tasklet);
760 
761 	mmc_free_host(mmc);
762 	return 0;
763 }
764 
765 static struct platform_driver cb710_mmc_driver = {
766 	.driver.name = "cb710-mmc",
767 	.probe = cb710_mmc_init,
768 	.remove = cb710_mmc_exit,
769 #ifdef CONFIG_PM
770 	.suspend = cb710_mmc_suspend,
771 	.resume = cb710_mmc_resume,
772 #endif
773 };
774 
775 module_platform_driver(cb710_mmc_driver);
776 
777 MODULE_AUTHOR("Michał Mirosław <mirq-linux@rere.qmqm.pl>");
778 MODULE_DESCRIPTION("ENE CB710 memory card reader driver - MMC/SD part");
779 MODULE_LICENSE("GPL");
780 MODULE_ALIAS("platform:cb710-mmc");
781