1/*
2 * MicroWire interface driver for OMAP
3 *
4 * Copyright 2003 MontaVista Software Inc. <source@mvista.com>
5 *
6 * Ported to 2.6 OMAP uwire interface.
7 * Copyright (C) 2004 Texas Instruments.
8 *
9 * Generalization patches by Juha Yrjola <juha.yrjola@nokia.com>
10 *
11 * Copyright (C) 2005 David Brownell (ported to 2.6 SPI interface)
12 * Copyright (C) 2006 Nokia
13 *
14 * Many updates by Imre Deak <imre.deak@nokia.com>
15 *
16 * This program is free software; you can redistribute it and/or modify it
17 * under the terms of the GNU General Public License as published by the
18 * Free Software Foundation; either version 2 of the License, or (at your
19 * option) any later version.
20 *
21 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
27 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
28 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32#include <linux/kernel.h>
33#include <linux/init.h>
34#include <linux/delay.h>
35#include <linux/platform_device.h>
36#include <linux/interrupt.h>
37#include <linux/err.h>
38#include <linux/clk.h>
39#include <linux/slab.h>
40#include <linux/device.h>
41
42#include <linux/spi/spi.h>
43#include <linux/spi/spi_bitbang.h>
44#include <linux/module.h>
45#include <linux/io.h>
46
47#include <mach/hardware.h>
48#include <asm/mach-types.h>
49
50#include <mach/mux.h>
51
52#include <mach/omap7xx.h>	/* OMAP7XX_IO_CONF registers */
53
54
55/* FIXME address is now a platform device resource,
56 * and irqs should show there too...
57 */
58#define UWIRE_BASE_PHYS		0xFFFB3000
59
60/* uWire Registers: */
61#define UWIRE_IO_SIZE 0x20
62#define UWIRE_TDR     0x00
63#define UWIRE_RDR     0x00
64#define UWIRE_CSR     0x01
65#define UWIRE_SR1     0x02
66#define UWIRE_SR2     0x03
67#define UWIRE_SR3     0x04
68#define UWIRE_SR4     0x05
69#define UWIRE_SR5     0x06
70
71/* CSR bits */
72#define	RDRB	(1 << 15)
73#define	CSRB	(1 << 14)
74#define	START	(1 << 13)
75#define	CS_CMD	(1 << 12)
76
77/* SR1 or SR2 bits */
78#define UWIRE_READ_FALLING_EDGE		0x0001
79#define UWIRE_READ_RISING_EDGE		0x0000
80#define UWIRE_WRITE_FALLING_EDGE	0x0000
81#define UWIRE_WRITE_RISING_EDGE		0x0002
82#define UWIRE_CS_ACTIVE_LOW		0x0000
83#define UWIRE_CS_ACTIVE_HIGH		0x0004
84#define UWIRE_FREQ_DIV_2		0x0000
85#define UWIRE_FREQ_DIV_4		0x0008
86#define UWIRE_FREQ_DIV_8		0x0010
87#define UWIRE_CHK_READY			0x0020
88#define UWIRE_CLK_INVERTED		0x0040
89
90
91struct uwire_spi {
92	struct spi_bitbang	bitbang;
93	struct clk		*ck;
94};
95
96struct uwire_state {
97	unsigned	div1_idx;
98};
99
100/* REVISIT compile time constant for idx_shift? */
101/*
102 * Or, put it in a structure which is used throughout the driver;
103 * that avoids having to issue two loads for each bit of static data.
104 */
105static unsigned int uwire_idx_shift;
106static void __iomem *uwire_base;
107
108static inline void uwire_write_reg(int idx, u16 val)
109{
110	__raw_writew(val, uwire_base + (idx << uwire_idx_shift));
111}
112
113static inline u16 uwire_read_reg(int idx)
114{
115	return __raw_readw(uwire_base + (idx << uwire_idx_shift));
116}
117
118static inline void omap_uwire_configure_mode(u8 cs, unsigned long flags)
119{
120	u16	w, val = 0;
121	int	shift, reg;
122
123	if (flags & UWIRE_CLK_INVERTED)
124		val ^= 0x03;
125	val = flags & 0x3f;
126	if (cs & 1)
127		shift = 6;
128	else
129		shift = 0;
130	if (cs <= 1)
131		reg = UWIRE_SR1;
132	else
133		reg = UWIRE_SR2;
134
135	w = uwire_read_reg(reg);
136	w &= ~(0x3f << shift);
137	w |= val << shift;
138	uwire_write_reg(reg, w);
139}
140
141static int wait_uwire_csr_flag(u16 mask, u16 val, int might_not_catch)
142{
143	u16 w;
144	int c = 0;
145	unsigned long max_jiffies = jiffies + HZ;
146
147	for (;;) {
148		w = uwire_read_reg(UWIRE_CSR);
149		if ((w & mask) == val)
150			break;
151		if (time_after(jiffies, max_jiffies)) {
152			printk(KERN_ERR "%s: timeout. reg=%#06x "
153					"mask=%#06x val=%#06x\n",
154			       __func__, w, mask, val);
155			return -1;
156		}
157		c++;
158		if (might_not_catch && c > 64)
159			break;
160	}
161	return 0;
162}
163
164static void uwire_set_clk1_div(int div1_idx)
165{
166	u16 w;
167
168	w = uwire_read_reg(UWIRE_SR3);
169	w &= ~(0x03 << 1);
170	w |= div1_idx << 1;
171	uwire_write_reg(UWIRE_SR3, w);
172}
173
174static void uwire_chipselect(struct spi_device *spi, int value)
175{
176	struct	uwire_state *ust = spi->controller_state;
177	u16	w;
178	int	old_cs;
179
180
181	BUG_ON(wait_uwire_csr_flag(CSRB, 0, 0));
182
183	w = uwire_read_reg(UWIRE_CSR);
184	old_cs = (w >> 10) & 0x03;
185	if (value == BITBANG_CS_INACTIVE || old_cs != spi->chip_select) {
186		/* Deselect this CS, or the previous CS */
187		w &= ~CS_CMD;
188		uwire_write_reg(UWIRE_CSR, w);
189	}
190	/* activate specfied chipselect */
191	if (value == BITBANG_CS_ACTIVE) {
192		uwire_set_clk1_div(ust->div1_idx);
193		/* invert clock? */
194		if (spi->mode & SPI_CPOL)
195			uwire_write_reg(UWIRE_SR4, 1);
196		else
197			uwire_write_reg(UWIRE_SR4, 0);
198
199		w = spi->chip_select << 10;
200		w |= CS_CMD;
201		uwire_write_reg(UWIRE_CSR, w);
202	}
203}
204
205static int uwire_txrx(struct spi_device *spi, struct spi_transfer *t)
206{
207	unsigned	len = t->len;
208	unsigned	bits = t->bits_per_word;
209	unsigned	bytes;
210	u16		val, w;
211	int		status = 0;
212
213	if (!t->tx_buf && !t->rx_buf)
214		return 0;
215
216	w = spi->chip_select << 10;
217	w |= CS_CMD;
218
219	if (t->tx_buf) {
220		const u8	*buf = t->tx_buf;
221
222		/* NOTE:  DMA could be used for TX transfers */
223
224		/* write one or two bytes at a time */
225		while (len >= 1) {
226			/* tx bit 15 is first sent; we byteswap multibyte words
227			 * (msb-first) on the way out from memory.
228			 */
229			val = *buf++;
230			if (bits > 8) {
231				bytes = 2;
232				val |= *buf++ << 8;
233			} else
234				bytes = 1;
235			val <<= 16 - bits;
236
237#ifdef	VERBOSE
238			pr_debug("%s: write-%d =%04x\n",
239					dev_name(&spi->dev), bits, val);
240#endif
241			if (wait_uwire_csr_flag(CSRB, 0, 0))
242				goto eio;
243
244			uwire_write_reg(UWIRE_TDR, val);
245
246			/* start write */
247			val = START | w | (bits << 5);
248
249			uwire_write_reg(UWIRE_CSR, val);
250			len -= bytes;
251
252			/* Wait till write actually starts.
253			 * This is needed with MPU clock 60+ MHz.
254			 * REVISIT: we may not have time to catch it...
255			 */
256			if (wait_uwire_csr_flag(CSRB, CSRB, 1))
257				goto eio;
258
259			status += bytes;
260		}
261
262		/* REVISIT:  save this for later to get more i/o overlap */
263		if (wait_uwire_csr_flag(CSRB, 0, 0))
264			goto eio;
265
266	} else if (t->rx_buf) {
267		u8		*buf = t->rx_buf;
268
269		/* read one or two bytes at a time */
270		while (len) {
271			if (bits > 8) {
272				bytes = 2;
273			} else
274				bytes = 1;
275
276			/* start read */
277			val = START | w | (bits << 0);
278			uwire_write_reg(UWIRE_CSR, val);
279			len -= bytes;
280
281			/* Wait till read actually starts */
282			(void) wait_uwire_csr_flag(CSRB, CSRB, 1);
283
284			if (wait_uwire_csr_flag(RDRB | CSRB,
285						RDRB, 0))
286				goto eio;
287
288			/* rx bit 0 is last received; multibyte words will
289			 * be properly byteswapped on the way to memory.
290			 */
291			val = uwire_read_reg(UWIRE_RDR);
292			val &= (1 << bits) - 1;
293			*buf++ = (u8) val;
294			if (bytes == 2)
295				*buf++ = val >> 8;
296			status += bytes;
297#ifdef	VERBOSE
298			pr_debug("%s: read-%d =%04x\n",
299					dev_name(&spi->dev), bits, val);
300#endif
301
302		}
303	}
304	return status;
305eio:
306	return -EIO;
307}
308
309static int uwire_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
310{
311	struct uwire_state	*ust = spi->controller_state;
312	struct uwire_spi	*uwire;
313	unsigned		flags = 0;
314	unsigned		hz;
315	unsigned long		rate;
316	int			div1_idx;
317	int			div1;
318	int			div2;
319	int			status;
320
321	uwire = spi_master_get_devdata(spi->master);
322
323	/* mode 0..3, clock inverted separately;
324	 * standard nCS signaling;
325	 * don't treat DI=high as "not ready"
326	 */
327	if (spi->mode & SPI_CS_HIGH)
328		flags |= UWIRE_CS_ACTIVE_HIGH;
329
330	if (spi->mode & SPI_CPOL)
331		flags |= UWIRE_CLK_INVERTED;
332
333	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
334	case SPI_MODE_0:
335	case SPI_MODE_3:
336		flags |= UWIRE_WRITE_FALLING_EDGE | UWIRE_READ_RISING_EDGE;
337		break;
338	case SPI_MODE_1:
339	case SPI_MODE_2:
340		flags |= UWIRE_WRITE_RISING_EDGE | UWIRE_READ_FALLING_EDGE;
341		break;
342	}
343
344	/* assume it's already enabled */
345	rate = clk_get_rate(uwire->ck);
346
347	if (t != NULL)
348		hz = t->speed_hz;
349	else
350		hz = spi->max_speed_hz;
351
352	if (!hz) {
353		pr_debug("%s: zero speed?\n", dev_name(&spi->dev));
354		status = -EINVAL;
355		goto done;
356	}
357
358	/* F_INT = mpu_xor_clk / DIV1 */
359	for (div1_idx = 0; div1_idx < 4; div1_idx++) {
360		switch (div1_idx) {
361		case 0:
362			div1 = 2;
363			break;
364		case 1:
365			div1 = 4;
366			break;
367		case 2:
368			div1 = 7;
369			break;
370		default:
371		case 3:
372			div1 = 10;
373			break;
374		}
375		div2 = (rate / div1 + hz - 1) / hz;
376		if (div2 <= 8)
377			break;
378	}
379	if (div1_idx == 4) {
380		pr_debug("%s: lowest clock %ld, need %d\n",
381			dev_name(&spi->dev), rate / 10 / 8, hz);
382		status = -EDOM;
383		goto done;
384	}
385
386	/* we have to cache this and reset in uwire_chipselect as this is a
387	 * global parameter and another uwire device can change it under
388	 * us */
389	ust->div1_idx = div1_idx;
390	uwire_set_clk1_div(div1_idx);
391
392	rate /= div1;
393
394	switch (div2) {
395	case 0:
396	case 1:
397	case 2:
398		flags |= UWIRE_FREQ_DIV_2;
399		rate /= 2;
400		break;
401	case 3:
402	case 4:
403		flags |= UWIRE_FREQ_DIV_4;
404		rate /= 4;
405		break;
406	case 5:
407	case 6:
408	case 7:
409	case 8:
410		flags |= UWIRE_FREQ_DIV_8;
411		rate /= 8;
412		break;
413	}
414	omap_uwire_configure_mode(spi->chip_select, flags);
415	pr_debug("%s: uwire flags %02x, armxor %lu KHz, SCK %lu KHz\n",
416			__func__, flags,
417			clk_get_rate(uwire->ck) / 1000,
418			rate / 1000);
419	status = 0;
420done:
421	return status;
422}
423
424static int uwire_setup(struct spi_device *spi)
425{
426	struct uwire_state *ust = spi->controller_state;
427
428	if (ust == NULL) {
429		ust = kzalloc(sizeof(*ust), GFP_KERNEL);
430		if (ust == NULL)
431			return -ENOMEM;
432		spi->controller_state = ust;
433	}
434
435	return uwire_setup_transfer(spi, NULL);
436}
437
438static void uwire_cleanup(struct spi_device *spi)
439{
440	kfree(spi->controller_state);
441}
442
443static void uwire_off(struct uwire_spi *uwire)
444{
445	uwire_write_reg(UWIRE_SR3, 0);
446	clk_disable(uwire->ck);
447	spi_master_put(uwire->bitbang.master);
448}
449
450static int uwire_probe(struct platform_device *pdev)
451{
452	struct spi_master	*master;
453	struct uwire_spi	*uwire;
454	int			status;
455
456	master = spi_alloc_master(&pdev->dev, sizeof *uwire);
457	if (!master)
458		return -ENODEV;
459
460	uwire = spi_master_get_devdata(master);
461
462	uwire_base = devm_ioremap(&pdev->dev, UWIRE_BASE_PHYS, UWIRE_IO_SIZE);
463	if (!uwire_base) {
464		dev_dbg(&pdev->dev, "can't ioremap UWIRE\n");
465		spi_master_put(master);
466		return -ENOMEM;
467	}
468
469	platform_set_drvdata(pdev, uwire);
470
471	uwire->ck = devm_clk_get(&pdev->dev, "fck");
472	if (IS_ERR(uwire->ck)) {
473		status = PTR_ERR(uwire->ck);
474		dev_dbg(&pdev->dev, "no functional clock?\n");
475		spi_master_put(master);
476		return status;
477	}
478	clk_enable(uwire->ck);
479
480	if (cpu_is_omap7xx())
481		uwire_idx_shift = 1;
482	else
483		uwire_idx_shift = 2;
484
485	uwire_write_reg(UWIRE_SR3, 1);
486
487	/* the spi->mode bits understood by this driver: */
488	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
489	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
490	master->flags = SPI_MASTER_HALF_DUPLEX;
491
492	master->bus_num = 2;	/* "official" */
493	master->num_chipselect = 4;
494	master->setup = uwire_setup;
495	master->cleanup = uwire_cleanup;
496
497	uwire->bitbang.master = master;
498	uwire->bitbang.chipselect = uwire_chipselect;
499	uwire->bitbang.setup_transfer = uwire_setup_transfer;
500	uwire->bitbang.txrx_bufs = uwire_txrx;
501
502	status = spi_bitbang_start(&uwire->bitbang);
503	if (status < 0) {
504		uwire_off(uwire);
505	}
506	return status;
507}
508
509static int uwire_remove(struct platform_device *pdev)
510{
511	struct uwire_spi	*uwire = platform_get_drvdata(pdev);
512
513	// FIXME remove all child devices, somewhere ...
514
515	spi_bitbang_stop(&uwire->bitbang);
516	uwire_off(uwire);
517	return 0;
518}
519
520/* work with hotplug and coldplug */
521MODULE_ALIAS("platform:omap_uwire");
522
523static struct platform_driver uwire_driver = {
524	.driver = {
525		.name		= "omap_uwire",
526	},
527	.probe = uwire_probe,
528	.remove = uwire_remove,
529	// suspend ... unuse ck
530	// resume ... use ck
531};
532
533static int __init omap_uwire_init(void)
534{
535	/* FIXME move these into the relevant board init code. also, include
536	 * H3 support; it uses tsc2101 like H2 (on a different chipselect).
537	 */
538
539	if (machine_is_omap_h2()) {
540		/* defaults: W21 SDO, U18 SDI, V19 SCL */
541		omap_cfg_reg(N14_1610_UWIRE_CS0);
542		omap_cfg_reg(N15_1610_UWIRE_CS1);
543	}
544	if (machine_is_omap_perseus2()) {
545		/* configure pins: MPU_UW_nSCS1, MPU_UW_SDO, MPU_UW_SCLK */
546		int val = omap_readl(OMAP7XX_IO_CONF_9) & ~0x00EEE000;
547		omap_writel(val | 0x00AAA000, OMAP7XX_IO_CONF_9);
548	}
549
550	return platform_driver_register(&uwire_driver);
551}
552
553static void __exit omap_uwire_exit(void)
554{
555	platform_driver_unregister(&uwire_driver);
556}
557
558subsys_initcall(omap_uwire_init);
559module_exit(omap_uwire_exit);
560
561MODULE_LICENSE("GPL");
562
563