1/*
  2 * Sequencer Serial Port (SSP) based SPI master driver
  3 *
  4 * Copyright (C) 2010 Texas Instruments Inc
  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 as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License for more details.
 15 *
 16 * You should have received a copy of the GNU General Public License
 17 * along with this program; if not, write to the Free Software
 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 19 */
 20
 21#include <linux/kernel.h>
 22#include <linux/err.h>
 23#include <linux/completion.h>
 24#include <linux/delay.h>
 25#include <linux/platform_device.h>
 26#include <linux/spi/spi.h>
 27#include <linux/mfd/ti_ssp.h>
 28
 29#define MODE_BITS	(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
 30
 31struct ti_ssp_spi {
 32	struct spi_master		*master;
 33	struct device			*dev;
 34	spinlock_t			lock;
 35	struct list_head		msg_queue;
 36	struct completion		complete;
 37	bool				shutdown;
 38	struct workqueue_struct		*workqueue;
 39	struct work_struct		work;
 40	u8				mode, bpw;
 41	int				cs_active;
 42	u32				pc_en, pc_dis, pc_wr, pc_rd;
 43	void				(*select)(int cs);
 44};
 45
 46static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
 47{
 48	u32 ret;
 49
 50	ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
 51	return ret;
 52}
 53
 54static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
 55{
 56	ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
 57}
 58
 59static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
 60		       struct spi_transfer *t)
 61{
 62	int count;
 63
 64	if (hw->bpw <= 8) {
 65		u8		*rx = t->rx_buf;
 66		const u8	*tx = t->tx_buf;
 67
 68		for (count = 0; count < t->len; count += 1) {
 69			if (t->tx_buf)
 70				ti_ssp_spi_tx(hw, *tx++);
 71			if (t->rx_buf)
 72				*rx++ = ti_ssp_spi_rx(hw);
 73		}
 74	} else if (hw->bpw <= 16) {
 75		u16		*rx = t->rx_buf;
 76		const u16	*tx = t->tx_buf;
 77
 78		for (count = 0; count < t->len; count += 2) {
 79			if (t->tx_buf)
 80				ti_ssp_spi_tx(hw, *tx++);
 81			if (t->rx_buf)
 82				*rx++ = ti_ssp_spi_rx(hw);
 83		}
 84	} else {
 85		u32		*rx = t->rx_buf;
 86		const u32	*tx = t->tx_buf;
 87
 88		for (count = 0; count < t->len; count += 4) {
 89			if (t->tx_buf)
 90				ti_ssp_spi_tx(hw, *tx++);
 91			if (t->rx_buf)
 92				*rx++ = ti_ssp_spi_rx(hw);
 93		}
 94	}
 95
 96	msg->actual_length += count; /* bytes transferred */
 97
 98	dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
 99		t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
100		hw->bpw, count, (count < t->len) ? " (under)" : "");
101
102	return (count < t->len) ? -EIO : 0; /* left over data */
103}
104
105static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
106{
107	cs_active = !!cs_active;
108	if (cs_active == hw->cs_active)
109		return;
110	ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
111	hw->cs_active = cs_active;
112}
113
114#define __SHIFT_OUT(bits)	(SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
115				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
116#define __SHIFT_IN(bits)	(SSP_OPCODE_SHIFT | SSP_IN_MODE  | \
117				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
118
119static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
120{
121	int error, idx = 0;
122	u32 seqram[16];
123	u32 cs_en, cs_dis, clk;
124	u32 topbits, botbits;
125
126	mode &= MODE_BITS;
127	if (mode == hw->mode && bpw == hw->bpw)
128		return 0;
129
130	cs_en  = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
131	cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW  : SSP_CS_HIGH;
132	clk    = (mode & SPI_CPOL)    ? SSP_CLK_HIGH : SSP_CLK_LOW;
133
134	/* Construct instructions */
135
136	/* Disable Chip Select */
137	hw->pc_dis = idx;
138	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
139	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_dis | clk;
140
141	/* Enable Chip Select */
142	hw->pc_en = idx;
143	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
144	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_en | clk;
145
146	/* Reads and writes need to be split for bpw > 16 */
147	topbits = (bpw > 16) ? 16 : bpw;
148	botbits = bpw - topbits;
149
150	/* Write */
151	hw->pc_wr = idx;
152	seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
153	if (botbits)
154		seqram[idx++] = __SHIFT_OUT(botbits)  | SSP_DATA_REG;
155	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
156
157	/* Read */
158	hw->pc_rd = idx;
159	if (botbits)
160		seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
161	seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
162	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
163
164	error = ti_ssp_load(hw->dev, 0, seqram, idx);
165	if (error < 0)
166		return error;
167
168	error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
169					  0 : SSP_EARLY_DIN));
170	if (error < 0)
171		return error;
172
173	hw->bpw = bpw;
174	hw->mode = mode;
175
176	return error;
177}
178
179static void ti_ssp_spi_work(struct work_struct *work)
180{
181	struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
182
183	spin_lock(&hw->lock);
184
185	 while (!list_empty(&hw->msg_queue)) {
186		struct spi_message	*m;
187		struct spi_device	*spi;
188		struct spi_transfer	*t = NULL;
189		int			status = 0;
190
191		m = container_of(hw->msg_queue.next, struct spi_message,
192				 queue);
193
194		list_del_init(&m->queue);
195
196		spin_unlock(&hw->lock);
197
198		spi = m->spi;
199
200		if (hw->select)
201			hw->select(spi->chip_select);
202
203		list_for_each_entry(t, &m->transfers, transfer_list) {
204			int bpw = spi->bits_per_word;
205			int xfer_status;
206
207			if (t->bits_per_word)
208				bpw = t->bits_per_word;
209
210			if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
211				break;
212
213			ti_ssp_spi_chip_select(hw, 1);
214
215			xfer_status = ti_ssp_spi_txrx(hw, m, t);
216			if (xfer_status < 0)
217				status = xfer_status;
218
219			if (t->delay_usecs)
220				udelay(t->delay_usecs);
221
222			if (t->cs_change)
223				ti_ssp_spi_chip_select(hw, 0);
224		}
225
226		ti_ssp_spi_chip_select(hw, 0);
227		m->status = status;
228		m->complete(m->context);
229
230		spin_lock(&hw->lock);
231	}
232
233	if (hw->shutdown)
234		complete(&hw->complete);
235
236	spin_unlock(&hw->lock);
237}
238
239static int ti_ssp_spi_setup(struct spi_device *spi)
240{
241	if (spi->bits_per_word > 32)
242		return -EINVAL;
243
244	return 0;
245}
246
247static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
248{
249	struct ti_ssp_spi	*hw;
250	struct spi_transfer	*t;
251	int			error = 0;
252
253	m->actual_length = 0;
254	m->status = -EINPROGRESS;
255
256	hw = spi_master_get_devdata(spi->master);
257
258	if (list_empty(&m->transfers) || !m->complete)
259		return -EINVAL;
260
261	list_for_each_entry(t, &m->transfers, transfer_list) {
262		if (t->len && !(t->rx_buf || t->tx_buf)) {
263			dev_err(&spi->dev, "invalid xfer, no buffer\n");
264			return -EINVAL;
265		}
266
267		if (t->len && t->rx_buf && t->tx_buf) {
268			dev_err(&spi->dev, "invalid xfer, full duplex\n");
269			return -EINVAL;
270		}
271
272		if (t->bits_per_word > 32) {
273			dev_err(&spi->dev, "invalid xfer width %d\n",
274				t->bits_per_word);
275			return -EINVAL;
276		}
277	}
278
279	spin_lock(&hw->lock);
280	if (hw->shutdown) {
281		error = -ESHUTDOWN;
282		goto error_unlock;
283	}
284	list_add_tail(&m->queue, &hw->msg_queue);
285	queue_work(hw->workqueue, &hw->work);
286error_unlock:
287	spin_unlock(&hw->lock);
288	return error;
289}
290
291static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
292{
293	const struct ti_ssp_spi_data *pdata;
294	struct ti_ssp_spi *hw;
295	struct spi_master *master;
296	struct device *dev = &pdev->dev;
297	int error = 0;
298
299	pdata = dev->platform_data;
300	if (!pdata) {
301		dev_err(dev, "platform data not found\n");
302		return -EINVAL;
303	}
304
305	master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
306	if (!master) {
307		dev_err(dev, "cannot allocate SPI master\n");
308		return -ENOMEM;
309	}
310
311	hw = spi_master_get_devdata(master);
312	platform_set_drvdata(pdev, hw);
313
314	hw->master = master;
315	hw->dev = dev;
316	hw->select = pdata->select;
317
318	spin_lock_init(&hw->lock);
319	init_completion(&hw->complete);
320	INIT_LIST_HEAD(&hw->msg_queue);
321	INIT_WORK(&hw->work, ti_ssp_spi_work);
322
323	hw->workqueue = create_singlethread_workqueue(dev_name(dev));
324	if (!hw->workqueue) {
325		error = -ENOMEM;
326		dev_err(dev, "work queue creation failed\n");
327		goto error_wq;
328	}
329
330	error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
331	if (error < 0) {
332		dev_err(dev, "io setup failed\n");
333		goto error_iosel;
334	}
335
336	master->bus_num		= pdev->id;
337	master->num_chipselect	= pdata->num_cs;
338	master->mode_bits	= MODE_BITS;
339	master->flags		= SPI_MASTER_HALF_DUPLEX;
340	master->setup		= ti_ssp_spi_setup;
341	master->transfer	= ti_ssp_spi_transfer;
342
343	error = spi_register_master(master);
344	if (error) {
345		dev_err(dev, "master registration failed\n");
346		goto error_reg;
347	}
348
349	return 0;
350
351error_reg:
352error_iosel:
353	destroy_workqueue(hw->workqueue);
354error_wq:
355	spi_master_put(master);
356	return error;
357}
358
359static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
360{
361	struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
362	int error;
363
364	hw->shutdown = 1;
365	while (!list_empty(&hw->msg_queue)) {
366		error = wait_for_completion_interruptible(&hw->complete);
367		if (error < 0) {
368			hw->shutdown = 0;
369			return error;
370		}
371	}
372	destroy_workqueue(hw->workqueue);
373	spi_unregister_master(hw->master);
374
375	return 0;
376}
377
378static struct platform_driver ti_ssp_spi_driver = {
379	.probe		= ti_ssp_spi_probe,
380	.remove		= __devexit_p(ti_ssp_spi_remove),
381	.driver		= {
382		.name	= "ti-ssp-spi",
383		.owner	= THIS_MODULE,
384	},
385};
386
387static int __init ti_ssp_spi_init(void)
388{
389	return platform_driver_register(&ti_ssp_spi_driver);
390}
391module_init(ti_ssp_spi_init);
392
393static void __exit ti_ssp_spi_exit(void)
394{
395	platform_driver_unregister(&ti_ssp_spi_driver);
396}
397module_exit(ti_ssp_spi_exit);
398
399MODULE_DESCRIPTION("SSP SPI Master");
400MODULE_AUTHOR("Cyril Chemparathy");
401MODULE_LICENSE("GPL");
402MODULE_ALIAS("platform:ti-ssp-spi");