1/*
2 * TXx9 SPI controller driver.
3 *
4 * Based on linux/arch/mips/tx4938/toshiba_rbtx4938/spi_txx9.c
5 * Copyright (C) 2000-2001 Toshiba Corporation
6 *
7 * 2003-2005 (c) MontaVista Software, Inc. This file is licensed under the
8 * terms of the GNU General Public License version 2. This program is
9 * licensed "as is" without any warranty of any kind, whether express
10 * or implied.
11 *
12 * Support for TX4938 in 2.6 - Manish Lachwani (mlachwani@mvista.com)
13 *
14 * Convert to generic SPI framework - Atsushi Nemoto (anemo@mba.ocn.ne.jp)
15 */
16#include <linux/init.h>
17#include <linux/delay.h>
18#include <linux/errno.h>
19#include <linux/interrupt.h>
20#include <linux/platform_device.h>
21#include <linux/sched.h>
22#include <linux/spinlock.h>
23#include <linux/workqueue.h>
24#include <linux/spi/spi.h>
25#include <linux/err.h>
26#include <linux/clk.h>
27#include <linux/io.h>
28#include <linux/module.h>
29#include <linux/gpio.h>
30
31
32#define SPI_FIFO_SIZE 4
33#define SPI_MAX_DIVIDER 0xff	/* Max. value for SPCR1.SER */
34#define SPI_MIN_DIVIDER 1	/* Min. value for SPCR1.SER */
35
36#define TXx9_SPMCR		0x00
37#define TXx9_SPCR0		0x04
38#define TXx9_SPCR1		0x08
39#define TXx9_SPFS		0x0c
40#define TXx9_SPSR		0x14
41#define TXx9_SPDR		0x18
42
43/* SPMCR : SPI Master Control */
44#define TXx9_SPMCR_OPMODE	0xc0
45#define TXx9_SPMCR_CONFIG	0x40
46#define TXx9_SPMCR_ACTIVE	0x80
47#define TXx9_SPMCR_SPSTP	0x02
48#define TXx9_SPMCR_BCLR		0x01
49
50/* SPCR0 : SPI Control 0 */
51#define TXx9_SPCR0_TXIFL_MASK	0xc000
52#define TXx9_SPCR0_RXIFL_MASK	0x3000
53#define TXx9_SPCR0_SIDIE	0x0800
54#define TXx9_SPCR0_SOEIE	0x0400
55#define TXx9_SPCR0_RBSIE	0x0200
56#define TXx9_SPCR0_TBSIE	0x0100
57#define TXx9_SPCR0_IFSPSE	0x0010
58#define TXx9_SPCR0_SBOS		0x0004
59#define TXx9_SPCR0_SPHA		0x0002
60#define TXx9_SPCR0_SPOL		0x0001
61
62/* SPSR : SPI Status */
63#define TXx9_SPSR_TBSI		0x8000
64#define TXx9_SPSR_RBSI		0x4000
65#define TXx9_SPSR_TBS_MASK	0x3800
66#define TXx9_SPSR_RBS_MASK	0x0700
67#define TXx9_SPSR_SPOE		0x0080
68#define TXx9_SPSR_IFSD		0x0008
69#define TXx9_SPSR_SIDLE		0x0004
70#define TXx9_SPSR_STRDY		0x0002
71#define TXx9_SPSR_SRRDY		0x0001
72
73
74struct txx9spi {
75	struct workqueue_struct	*workqueue;
76	struct work_struct work;
77	spinlock_t lock;	/* protect 'queue' */
78	struct list_head queue;
79	wait_queue_head_t waitq;
80	void __iomem *membase;
81	int baseclk;
82	struct clk *clk;
83	int last_chipselect;
84	int last_chipselect_val;
85};
86
87static u32 txx9spi_rd(struct txx9spi *c, int reg)
88{
89	return __raw_readl(c->membase + reg);
90}
91static void txx9spi_wr(struct txx9spi *c, u32 val, int reg)
92{
93	__raw_writel(val, c->membase + reg);
94}
95
96static void txx9spi_cs_func(struct spi_device *spi, struct txx9spi *c,
97		int on, unsigned int cs_delay)
98{
99	int val = (spi->mode & SPI_CS_HIGH) ? on : !on;
100
101	if (on) {
102		/* deselect the chip with cs_change hint in last transfer */
103		if (c->last_chipselect >= 0)
104			gpio_set_value(c->last_chipselect,
105					!c->last_chipselect_val);
106		c->last_chipselect = spi->chip_select;
107		c->last_chipselect_val = val;
108	} else {
109		c->last_chipselect = -1;
110		ndelay(cs_delay);	/* CS Hold Time */
111	}
112	gpio_set_value(spi->chip_select, val);
113	ndelay(cs_delay);	/* CS Setup Time / CS Recovery Time */
114}
115
116static int txx9spi_setup(struct spi_device *spi)
117{
118	struct txx9spi *c = spi_master_get_devdata(spi->master);
119
120	if (!spi->max_speed_hz)
121		return -EINVAL;
122
123	if (gpio_direction_output(spi->chip_select,
124			!(spi->mode & SPI_CS_HIGH))) {
125		dev_err(&spi->dev, "Cannot setup GPIO for chipselect.\n");
126		return -EINVAL;
127	}
128
129	/* deselect chip */
130	spin_lock(&c->lock);
131	txx9spi_cs_func(spi, c, 0, (NSEC_PER_SEC / 2) / spi->max_speed_hz);
132	spin_unlock(&c->lock);
133
134	return 0;
135}
136
137static irqreturn_t txx9spi_interrupt(int irq, void *dev_id)
138{
139	struct txx9spi *c = dev_id;
140
141	/* disable rx intr */
142	txx9spi_wr(c, txx9spi_rd(c, TXx9_SPCR0) & ~TXx9_SPCR0_RBSIE,
143			TXx9_SPCR0);
144	wake_up(&c->waitq);
145	return IRQ_HANDLED;
146}
147
148static void txx9spi_work_one(struct txx9spi *c, struct spi_message *m)
149{
150	struct spi_device *spi = m->spi;
151	struct spi_transfer *t;
152	unsigned int cs_delay;
153	unsigned int cs_change = 1;
154	int status = 0;
155	u32 mcr;
156	u32 prev_speed_hz = 0;
157	u8 prev_bits_per_word = 0;
158
159	/* CS setup/hold/recovery time in nsec */
160	cs_delay = 100 + (NSEC_PER_SEC / 2) / spi->max_speed_hz;
161
162	mcr = txx9spi_rd(c, TXx9_SPMCR);
163	if (unlikely((mcr & TXx9_SPMCR_OPMODE) == TXx9_SPMCR_ACTIVE)) {
164		dev_err(&spi->dev, "Bad mode.\n");
165		status = -EIO;
166		goto exit;
167	}
168	mcr &= ~(TXx9_SPMCR_OPMODE | TXx9_SPMCR_SPSTP | TXx9_SPMCR_BCLR);
169
170	/* enter config mode */
171	txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
172	txx9spi_wr(c, TXx9_SPCR0_SBOS
173			| ((spi->mode & SPI_CPOL) ? TXx9_SPCR0_SPOL : 0)
174			| ((spi->mode & SPI_CPHA) ? TXx9_SPCR0_SPHA : 0)
175			| 0x08,
176			TXx9_SPCR0);
177
178	list_for_each_entry(t, &m->transfers, transfer_list) {
179		const void *txbuf = t->tx_buf;
180		void *rxbuf = t->rx_buf;
181		u32 data;
182		unsigned int len = t->len;
183		unsigned int wsize;
184		u32 speed_hz = t->speed_hz ? : spi->max_speed_hz;
185		u8 bits_per_word = t->bits_per_word;
186
187		wsize = bits_per_word >> 3; /* in bytes */
188
189		if (prev_speed_hz != speed_hz
190				|| prev_bits_per_word != bits_per_word) {
191			int n = DIV_ROUND_UP(c->baseclk, speed_hz) - 1;
192
193			n = clamp(n, SPI_MIN_DIVIDER, SPI_MAX_DIVIDER);
194			/* enter config mode */
195			txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,
196					TXx9_SPMCR);
197			txx9spi_wr(c, (n << 8) | bits_per_word, TXx9_SPCR1);
198			/* enter active mode */
199			txx9spi_wr(c, mcr | TXx9_SPMCR_ACTIVE, TXx9_SPMCR);
200
201			prev_speed_hz = speed_hz;
202			prev_bits_per_word = bits_per_word;
203		}
204
205		if (cs_change)
206			txx9spi_cs_func(spi, c, 1, cs_delay);
207		cs_change = t->cs_change;
208		while (len) {
209			unsigned int count = SPI_FIFO_SIZE;
210			int i;
211			u32 cr0;
212
213			if (len < count * wsize)
214				count = len / wsize;
215			/* now tx must be idle... */
216			while (!(txx9spi_rd(c, TXx9_SPSR) & TXx9_SPSR_SIDLE))
217				cpu_relax();
218			cr0 = txx9spi_rd(c, TXx9_SPCR0);
219			cr0 &= ~TXx9_SPCR0_RXIFL_MASK;
220			cr0 |= (count - 1) << 12;
221			/* enable rx intr */
222			cr0 |= TXx9_SPCR0_RBSIE;
223			txx9spi_wr(c, cr0, TXx9_SPCR0);
224			/* send */
225			for (i = 0; i < count; i++) {
226				if (txbuf) {
227					data = (wsize == 1)
228						? *(const u8 *)txbuf
229						: *(const u16 *)txbuf;
230					txx9spi_wr(c, data, TXx9_SPDR);
231					txbuf += wsize;
232				} else
233					txx9spi_wr(c, 0, TXx9_SPDR);
234			}
235			/* wait all rx data */
236			wait_event(c->waitq,
237				txx9spi_rd(c, TXx9_SPSR) & TXx9_SPSR_RBSI);
238			/* receive */
239			for (i = 0; i < count; i++) {
240				data = txx9spi_rd(c, TXx9_SPDR);
241				if (rxbuf) {
242					if (wsize == 1)
243						*(u8 *)rxbuf = data;
244					else
245						*(u16 *)rxbuf = data;
246					rxbuf += wsize;
247				}
248			}
249			len -= count * wsize;
250		}
251		m->actual_length += t->len;
252		if (t->delay_usecs)
253			udelay(t->delay_usecs);
254
255		if (!cs_change)
256			continue;
257		if (t->transfer_list.next == &m->transfers)
258			break;
259		/* sometimes a short mid-message deselect of the chip
260		 * may be needed to terminate a mode or command
261		 */
262		txx9spi_cs_func(spi, c, 0, cs_delay);
263	}
264
265exit:
266	m->status = status;
267	if (m->complete)
268		m->complete(m->context);
269
270	/* normally deactivate chipselect ... unless no error and
271	 * cs_change has hinted that the next message will probably
272	 * be for this chip too.
273	 */
274	if (!(status == 0 && cs_change))
275		txx9spi_cs_func(spi, c, 0, cs_delay);
276
277	/* enter config mode */
278	txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
279}
280
281static void txx9spi_work(struct work_struct *work)
282{
283	struct txx9spi *c = container_of(work, struct txx9spi, work);
284	unsigned long flags;
285
286	spin_lock_irqsave(&c->lock, flags);
287	while (!list_empty(&c->queue)) {
288		struct spi_message *m;
289
290		m = container_of(c->queue.next, struct spi_message, queue);
291		list_del_init(&m->queue);
292		spin_unlock_irqrestore(&c->lock, flags);
293
294		txx9spi_work_one(c, m);
295
296		spin_lock_irqsave(&c->lock, flags);
297	}
298	spin_unlock_irqrestore(&c->lock, flags);
299}
300
301static int txx9spi_transfer(struct spi_device *spi, struct spi_message *m)
302{
303	struct spi_master *master = spi->master;
304	struct txx9spi *c = spi_master_get_devdata(master);
305	struct spi_transfer *t;
306	unsigned long flags;
307
308	m->actual_length = 0;
309
310	/* check each transfer's parameters */
311	list_for_each_entry(t, &m->transfers, transfer_list) {
312		if (!t->tx_buf && !t->rx_buf && t->len)
313			return -EINVAL;
314	}
315
316	spin_lock_irqsave(&c->lock, flags);
317	list_add_tail(&m->queue, &c->queue);
318	queue_work(c->workqueue, &c->work);
319	spin_unlock_irqrestore(&c->lock, flags);
320
321	return 0;
322}
323
324static int txx9spi_probe(struct platform_device *dev)
325{
326	struct spi_master *master;
327	struct txx9spi *c;
328	struct resource *res;
329	int ret = -ENODEV;
330	u32 mcr;
331	int irq;
332
333	master = spi_alloc_master(&dev->dev, sizeof(*c));
334	if (!master)
335		return ret;
336	c = spi_master_get_devdata(master);
337	platform_set_drvdata(dev, master);
338
339	INIT_WORK(&c->work, txx9spi_work);
340	spin_lock_init(&c->lock);
341	INIT_LIST_HEAD(&c->queue);
342	init_waitqueue_head(&c->waitq);
343
344	c->clk = devm_clk_get(&dev->dev, "spi-baseclk");
345	if (IS_ERR(c->clk)) {
346		ret = PTR_ERR(c->clk);
347		c->clk = NULL;
348		goto exit;
349	}
350	ret = clk_enable(c->clk);
351	if (ret) {
352		c->clk = NULL;
353		goto exit;
354	}
355	c->baseclk = clk_get_rate(c->clk);
356	master->min_speed_hz = DIV_ROUND_UP(c->baseclk, SPI_MAX_DIVIDER + 1);
357	master->max_speed_hz = c->baseclk / (SPI_MIN_DIVIDER + 1);
358
359	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
360	c->membase = devm_ioremap_resource(&dev->dev, res);
361	if (IS_ERR(c->membase))
362		goto exit_busy;
363
364	/* enter config mode */
365	mcr = txx9spi_rd(c, TXx9_SPMCR);
366	mcr &= ~(TXx9_SPMCR_OPMODE | TXx9_SPMCR_SPSTP | TXx9_SPMCR_BCLR);
367	txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
368
369	irq = platform_get_irq(dev, 0);
370	if (irq < 0)
371		goto exit_busy;
372	ret = devm_request_irq(&dev->dev, irq, txx9spi_interrupt, 0,
373			       "spi_txx9", c);
374	if (ret)
375		goto exit;
376
377	c->workqueue = create_singlethread_workqueue(
378				dev_name(master->dev.parent));
379	if (!c->workqueue)
380		goto exit_busy;
381	c->last_chipselect = -1;
382
383	dev_info(&dev->dev, "at %#llx, irq %d, %dMHz\n",
384		 (unsigned long long)res->start, irq,
385		 (c->baseclk + 500000) / 1000000);
386
387	/* the spi->mode bits understood by this driver: */
388	master->mode_bits = SPI_CS_HIGH | SPI_CPOL | SPI_CPHA;
389
390	master->bus_num = dev->id;
391	master->setup = txx9spi_setup;
392	master->transfer = txx9spi_transfer;
393	master->num_chipselect = (u16)UINT_MAX; /* any GPIO numbers */
394	master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
395
396	ret = devm_spi_register_master(&dev->dev, master);
397	if (ret)
398		goto exit;
399	return 0;
400exit_busy:
401	ret = -EBUSY;
402exit:
403	if (c->workqueue)
404		destroy_workqueue(c->workqueue);
405	clk_disable(c->clk);
406	spi_master_put(master);
407	return ret;
408}
409
410static int txx9spi_remove(struct platform_device *dev)
411{
412	struct spi_master *master = platform_get_drvdata(dev);
413	struct txx9spi *c = spi_master_get_devdata(master);
414
415	destroy_workqueue(c->workqueue);
416	clk_disable(c->clk);
417	return 0;
418}
419
420/* work with hotplug and coldplug */
421MODULE_ALIAS("platform:spi_txx9");
422
423static struct platform_driver txx9spi_driver = {
424	.probe = txx9spi_probe,
425	.remove = txx9spi_remove,
426	.driver = {
427		.name = "spi_txx9",
428	},
429};
430
431static int __init txx9spi_init(void)
432{
433	return platform_driver_register(&txx9spi_driver);
434}
435subsys_initcall(txx9spi_init);
436
437static void __exit txx9spi_exit(void)
438{
439	platform_driver_unregister(&txx9spi_driver);
440}
441module_exit(txx9spi_exit);
442
443MODULE_DESCRIPTION("TXx9 SPI Driver");
444MODULE_LICENSE("GPL");
445