summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi-omap-uwire.c
blob: 55576db315497379d73d6f2513b2bbfadb32d2d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
/*
 * MicroWire interface driver for OMAP
 *
 * Copyright 2003 MontaVista Software Inc. <source@mvista.com>
 *
 * Ported to 2.6 OMAP uwire interface.
 * Copyright (C) 2004 Texas Instruments.
 *
 * Generalization patches by Juha Yrjola <juha.yrjola@nokia.com>
 *
 * Copyright (C) 2005 David Brownell (ported to 2.6 SPI interface)
 * Copyright (C) 2006 Nokia
 *
 * Many updates by Imre Deak <imre.deak@nokia.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/device.h>

#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/module.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/mach-types.h>

#include <mach/mux.h>

#include <mach/omap7xx.h>	/* OMAP7XX_IO_CONF registers */


/* FIXME address is now a platform device resource,
 * and irqs should show there too...
 */
#define UWIRE_BASE_PHYS		0xFFFB3000

/* uWire Registers: */
#define UWIRE_IO_SIZE 0x20
#define UWIRE_TDR     0x00
#define UWIRE_RDR     0x00
#define UWIRE_CSR     0x01
#define UWIRE_SR1     0x02
#define UWIRE_SR2     0x03
#define UWIRE_SR3     0x04
#define UWIRE_SR4     0x05
#define UWIRE_SR5     0x06

/* CSR bits */
#define	RDRB	(1 << 15)
#define	CSRB	(1 << 14)
#define	START	(1 << 13)
#define	CS_CMD	(1 << 12)

/* SR1 or SR2 bits */
#define UWIRE_READ_FALLING_EDGE		0x0001
#define UWIRE_READ_RISING_EDGE		0x0000
#define UWIRE_WRITE_FALLING_EDGE	0x0000
#define UWIRE_WRITE_RISING_EDGE		0x0002
#define UWIRE_CS_ACTIVE_LOW		0x0000
#define UWIRE_CS_ACTIVE_HIGH		0x0004
#define UWIRE_FREQ_DIV_2		0x0000
#define UWIRE_FREQ_DIV_4		0x0008
#define UWIRE_FREQ_DIV_8		0x0010
#define UWIRE_CHK_READY			0x0020
#define UWIRE_CLK_INVERTED		0x0040


struct uwire_spi {
	struct spi_bitbang	bitbang;
	struct clk		*ck;
};

struct uwire_state {
	unsigned	div1_idx;
};

/* REVISIT compile time constant for idx_shift? */
/*
 * Or, put it in a structure which is used throughout the driver;
 * that avoids having to issue two loads for each bit of static data.
 */
static unsigned int uwire_idx_shift;
static void __iomem *uwire_base;

static inline void uwire_write_reg(int idx, u16 val)
{
	__raw_writew(val, uwire_base + (idx << uwire_idx_shift));
}

static inline u16 uwire_read_reg(int idx)
{
	return __raw_readw(uwire_base + (idx << uwire_idx_shift));
}

static inline void omap_uwire_configure_mode(u8 cs, unsigned long flags)
{
	u16	w, val = 0;
	int	shift, reg;

	if (flags & UWIRE_CLK_INVERTED)
		val ^= 0x03;
	val = flags & 0x3f;
	if (cs & 1)
		shift = 6;
	else
		shift = 0;
	if (cs <= 1)
		reg = UWIRE_SR1;
	else
		reg = UWIRE_SR2;

	w = uwire_read_reg(reg);
	w &= ~(0x3f << shift);
	w |= val << shift;
	uwire_write_reg(reg, w);
}

static int wait_uwire_csr_flag(u16 mask, u16 val, int might_not_catch)
{
	u16 w;
	int c = 0;
	unsigned long max_jiffies = jiffies + HZ;

	for (;;) {
		w = uwire_read_reg(UWIRE_CSR);
		if ((w & mask) == val)
			break;
		if (time_after(jiffies, max_jiffies)) {
			printk(KERN_ERR "%s: timeout. reg=%#06x "
					"mask=%#06x val=%#06x\n",
			       __func__, w, mask, val);
			return -1;
		}
		c++;
		if (might_not_catch && c > 64)
			break;
	}
	return 0;
}

static void uwire_set_clk1_div(int div1_idx)
{
	u16 w;

	w = uwire_read_reg(UWIRE_SR3);
	w &= ~(0x03 << 1);
	w |= div1_idx << 1;
	uwire_write_reg(UWIRE_SR3, w);
}

static void uwire_chipselect(struct spi_device *spi, int value)
{
	struct	uwire_state *ust = spi->controller_state;
	u16	w;
	int	old_cs;


	BUG_ON(wait_uwire_csr_flag(CSRB, 0, 0));

	w = uwire_read_reg(UWIRE_CSR);
	old_cs = (w >> 10) & 0x03;
	if (value == BITBANG_CS_INACTIVE || old_cs != spi->chip_select) {
		/* Deselect this CS, or the previous CS */
		w &= ~CS_CMD;
		uwire_write_reg(UWIRE_CSR, w);
	}
	/* activate specfied chipselect */
	if (value == BITBANG_CS_ACTIVE) {
		uwire_set_clk1_div(ust->div1_idx);
		/* invert clock? */
		if (spi->mode & SPI_CPOL)
			uwire_write_reg(UWIRE_SR4, 1);
		else
			uwire_write_reg(UWIRE_SR4, 0);

		w = spi->chip_select << 10;
		w |= CS_CMD;
		uwire_write_reg(UWIRE_CSR, w);
	}
}

static int uwire_txrx(struct spi_device *spi, struct spi_transfer *t)
{
	unsigned	len = t->len;
	unsigned	bits = t->bits_per_word ? : spi->bits_per_word;
	unsigned	bytes;
	u16		val, w;
	int		status = 0;

	if (!t->tx_buf && !t->rx_buf)
		return 0;

	w = spi->chip_select << 10;
	w |= CS_CMD;

	if (t->tx_buf) {
		const u8	*buf = t->tx_buf;

		/* NOTE:  DMA could be used for TX transfers */

		/* write one or two bytes at a time */
		while (len >= 1) {
			/* tx bit 15 is first sent; we byteswap multibyte words
			 * (msb-first) on the way out from memory.
			 */
			val = *buf++;
			if (bits > 8) {
				bytes = 2;
				val |= *buf++ << 8;
			} else
				bytes = 1;
			val <<= 16 - bits;

#ifdef	VERBOSE
			pr_debug("%s: write-%d =%04x\n",
					dev_name(&spi->dev), bits, val);
#endif
			if (wait_uwire_csr_flag(CSRB, 0, 0))
				goto eio;

			uwire_write_reg(UWIRE_TDR, val);

			/* start write */
			val = START | w | (bits << 5);

			uwire_write_reg(UWIRE_CSR, val);
			len -= bytes;

			/* Wait till write actually starts.
			 * This is needed with MPU clock 60+ MHz.
			 * REVISIT: we may not have time to catch it...
			 */
			if (wait_uwire_csr_flag(CSRB, CSRB, 1))
				goto eio;

			status += bytes;
		}

		/* REVISIT:  save this for later to get more i/o overlap */
		if (wait_uwire_csr_flag(CSRB, 0, 0))
			goto eio;

	} else if (t->rx_buf) {
		u8		*buf = t->rx_buf;

		/* read one or two bytes at a time */
		while (len) {
			if (bits > 8) {
				bytes = 2;
			} else
				bytes = 1;

			/* start read */
			val = START | w | (bits << 0);
			uwire_write_reg(UWIRE_CSR, val);
			len -= bytes;

			/* Wait till read actually starts */
			(void) wait_uwire_csr_flag(CSRB, CSRB, 1);

			if (wait_uwire_csr_flag(RDRB | CSRB,
						RDRB, 0))
				goto eio;

			/* rx bit 0 is last received; multibyte words will
			 * be properly byteswapped on the way to memory.
			 */
			val = uwire_read_reg(UWIRE_RDR);
			val &= (1 << bits) - 1;
			*buf++ = (u8) val;
			if (bytes == 2)
				*buf++ = val >> 8;
			status += bytes;
#ifdef	VERBOSE
			pr_debug("%s: read-%d =%04x\n",
					dev_name(&spi->dev), bits, val);
#endif

		}
	}
	return status;
eio:
	return -EIO;
}

static int uwire_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
{
	struct uwire_state	*ust = spi->controller_state;
	struct uwire_spi	*uwire;
	unsigned		flags = 0;
	unsigned		hz;
	unsigned long		rate;
	int			div1_idx;
	int			div1;
	int			div2;
	int			status;

	uwire = spi_master_get_devdata(spi->master);

	/* mode 0..3, clock inverted separately;
	 * standard nCS signaling;
	 * don't treat DI=high as "not ready"
	 */
	if (spi->mode & SPI_CS_HIGH)
		flags |= UWIRE_CS_ACTIVE_HIGH;

	if (spi->mode & SPI_CPOL)
		flags |= UWIRE_CLK_INVERTED;

	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
	case SPI_MODE_0:
	case SPI_MODE_3:
		flags |= UWIRE_WRITE_FALLING_EDGE | UWIRE_READ_RISING_EDGE;
		break;
	case SPI_MODE_1:
	case SPI_MODE_2:
		flags |= UWIRE_WRITE_RISING_EDGE | UWIRE_READ_FALLING_EDGE;
		break;
	}

	/* assume it's already enabled */
	rate = clk_get_rate(uwire->ck);

	hz = spi->max_speed_hz;
	if (t != NULL && t->speed_hz)
		hz = t->speed_hz;

	if (!hz) {
		pr_debug("%s: zero speed?\n", dev_name(&spi->dev));
		status = -EINVAL;
		goto done;
	}

	/* F_INT = mpu_xor_clk / DIV1 */
	for (div1_idx = 0; div1_idx < 4; div1_idx++) {
		switch (div1_idx) {
		case 0:
			div1 = 2;
			break;
		case 1:
			div1 = 4;
			break;
		case 2:
			div1 = 7;
			break;
		default:
		case 3:
			div1 = 10;
			break;
		}
		div2 = (rate / div1 + hz - 1) / hz;
		if (div2 <= 8)
			break;
	}
	if (div1_idx == 4) {
		pr_debug("%s: lowest clock %ld, need %d\n",
			dev_name(&spi->dev), rate / 10 / 8, hz);
		status = -EDOM;
		goto done;
	}

	/* we have to cache this and reset in uwire_chipselect as this is a
	 * global parameter and another uwire device can change it under
	 * us */
	ust->div1_idx = div1_idx;
	uwire_set_clk1_div(div1_idx);

	rate /= div1;

	switch (div2) {
	case 0:
	case 1:
	case 2:
		flags |= UWIRE_FREQ_DIV_2;
		rate /= 2;
		break;
	case 3:
	case 4:
		flags |= UWIRE_FREQ_DIV_4;
		rate /= 4;
		break;
	case 5:
	case 6:
	case 7:
	case 8:
		flags |= UWIRE_FREQ_DIV_8;
		rate /= 8;
		break;
	}
	omap_uwire_configure_mode(spi->chip_select, flags);
	pr_debug("%s: uwire flags %02x, armxor %lu KHz, SCK %lu KHz\n",
			__func__, flags,
			clk_get_rate(uwire->ck) / 1000,
			rate / 1000);
	status = 0;
done:
	return status;
}

static int uwire_setup(struct spi_device *spi)
{
	struct uwire_state *ust = spi->controller_state;

	if (ust == NULL) {
		ust = kzalloc(sizeof(*ust), GFP_KERNEL);
		if (ust == NULL)
			return -ENOMEM;
		spi->controller_state = ust;
	}

	return uwire_setup_transfer(spi, NULL);
}

static void uwire_cleanup(struct spi_device *spi)
{
	kfree(spi->controller_state);
}

static void uwire_off(struct uwire_spi *uwire)
{
	uwire_write_reg(UWIRE_SR3, 0);
	clk_disable(uwire->ck);
	spi_master_put(uwire->bitbang.master);
}

static int uwire_probe(struct platform_device *pdev)
{
	struct spi_master	*master;
	struct uwire_spi	*uwire;
	int			status;

	master = spi_alloc_master(&pdev->dev, sizeof *uwire);
	if (!master)
		return -ENODEV;

	uwire = spi_master_get_devdata(master);

	uwire_base = devm_ioremap(&pdev->dev, UWIRE_BASE_PHYS, UWIRE_IO_SIZE);
	if (!uwire_base) {
		dev_dbg(&pdev->dev, "can't ioremap UWIRE\n");
		spi_master_put(master);
		return -ENOMEM;
	}

	platform_set_drvdata(pdev, uwire);

	uwire->ck = devm_clk_get(&pdev->dev, "fck");
	if (IS_ERR(uwire->ck)) {
		status = PTR_ERR(uwire->ck);
		dev_dbg(&pdev->dev, "no functional clock?\n");
		spi_master_put(master);
		return status;
	}
	clk_enable(uwire->ck);

	if (cpu_is_omap7xx())
		uwire_idx_shift = 1;
	else
		uwire_idx_shift = 2;

	uwire_write_reg(UWIRE_SR3, 1);

	/* the spi->mode bits understood by this driver: */
	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
	master->flags = SPI_MASTER_HALF_DUPLEX;

	master->bus_num = 2;	/* "official" */
	master->num_chipselect = 4;
	master->setup = uwire_setup;
	master->cleanup = uwire_cleanup;

	uwire->bitbang.master = master;
	uwire->bitbang.chipselect = uwire_chipselect;
	uwire->bitbang.setup_transfer = uwire_setup_transfer;
	uwire->bitbang.txrx_bufs = uwire_txrx;

	status = spi_bitbang_start(&uwire->bitbang);
	if (status < 0) {
		uwire_off(uwire);
	}
	return status;
}

static int uwire_remove(struct platform_device *pdev)
{
	struct uwire_spi	*uwire = platform_get_drvdata(pdev);

	// FIXME remove all child devices, somewhere ...

	spi_bitbang_stop(&uwire->bitbang);
	uwire_off(uwire);
	return 0;
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:omap_uwire");

static struct platform_driver uwire_driver = {
	.driver = {
		.name		= "omap_uwire",
	},
	.probe = uwire_probe,
	.remove = uwire_remove,
	// suspend ... unuse ck
	// resume ... use ck
};

static int __init omap_uwire_init(void)
{
	/* FIXME move these into the relevant board init code. also, include
	 * H3 support; it uses tsc2101 like H2 (on a different chipselect).
	 */

	if (machine_is_omap_h2()) {
		/* defaults: W21 SDO, U18 SDI, V19 SCL */
		omap_cfg_reg(N14_1610_UWIRE_CS0);
		omap_cfg_reg(N15_1610_UWIRE_CS1);
	}
	if (machine_is_omap_perseus2()) {
		/* configure pins: MPU_UW_nSCS1, MPU_UW_SDO, MPU_UW_SCLK */
		int val = omap_readl(OMAP7XX_IO_CONF_9) & ~0x00EEE000;
		omap_writel(val | 0x00AAA000, OMAP7XX_IO_CONF_9);
	}

	return platform_driver_register(&uwire_driver);
}

static void __exit omap_uwire_exit(void)
{
	platform_driver_unregister(&uwire_driver);
}

subsys_initcall(omap_uwire_init);
module_exit(omap_uwire_exit);

MODULE_LICENSE("GPL");