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/module.h>
 26#include <linux/platform_device.h>
 27#include <linux/spi/spi.h>
 28#include <linux/mfd/ti_ssp.h>
 29
 30#define MODE_BITS	(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
 31
 32struct ti_ssp_spi {
 33	struct spi_master		*master;
 34	struct device			*dev;
 35	spinlock_t			lock;
 36	struct list_head		msg_queue;
 37	struct completion		complete;
 38	bool				shutdown;
 39	struct workqueue_struct		*workqueue;
 40	struct work_struct		work;
 41	u8				mode, bpw;
 42	int				cs_active;
 43	u32				pc_en, pc_dis, pc_wr, pc_rd;
 44	void				(*select)(int cs);
 45};
 46
 47static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
 48{
 49	u32 ret;
 50
 51	ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
 52	return ret;
 53}
 54
 55static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
 56{
 57	ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
 58}
 59
 60static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
 61		       struct spi_transfer *t)
 62{
 63	int count;
 64
 65	if (hw->bpw <= 8) {
 66		u8		*rx = t->rx_buf;
 67		const u8	*tx = t->tx_buf;
 68
 69		for (count = 0; count < t->len; count += 1) {
 70			if (t->tx_buf)
 71				ti_ssp_spi_tx(hw, *tx++);
 72			if (t->rx_buf)
 73				*rx++ = ti_ssp_spi_rx(hw);
 74		}
 75	} else if (hw->bpw <= 16) {
 76		u16		*rx = t->rx_buf;
 77		const u16	*tx = t->tx_buf;
 78
 79		for (count = 0; count < t->len; count += 2) {
 80			if (t->tx_buf)
 81				ti_ssp_spi_tx(hw, *tx++);
 82			if (t->rx_buf)
 83				*rx++ = ti_ssp_spi_rx(hw);
 84		}
 85	} else {
 86		u32		*rx = t->rx_buf;
 87		const u32	*tx = t->tx_buf;
 88
 89		for (count = 0; count < t->len; count += 4) {
 90			if (t->tx_buf)
 91				ti_ssp_spi_tx(hw, *tx++);
 92			if (t->rx_buf)
 93				*rx++ = ti_ssp_spi_rx(hw);
 94		}
 95	}
 96
 97	msg->actual_length += count; /* bytes transferred */
 98
 99	dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
100		t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
101		hw->bpw, count, (count < t->len) ? " (under)" : "");
102
103	return (count < t->len) ? -EIO : 0; /* left over data */
104}
105
106static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
107{
108	cs_active = !!cs_active;
109	if (cs_active == hw->cs_active)
110		return;
111	ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
112	hw->cs_active = cs_active;
113}
114
115#define __SHIFT_OUT(bits)	(SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
116				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
117#define __SHIFT_IN(bits)	(SSP_OPCODE_SHIFT | SSP_IN_MODE  | \
118				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
119
120static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
121{
122	int error, idx = 0;
123	u32 seqram[16];
124	u32 cs_en, cs_dis, clk;
125	u32 topbits, botbits;
126
127	mode &= MODE_BITS;
128	if (mode == hw->mode && bpw == hw->bpw)
129		return 0;
130
131	cs_en  = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
132	cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW  : SSP_CS_HIGH;
133	clk    = (mode & SPI_CPOL)    ? SSP_CLK_HIGH : SSP_CLK_LOW;
134
135	/* Construct instructions */
136
137	/* Disable Chip Select */
138	hw->pc_dis = idx;
139	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
140	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_dis | clk;
141
142	/* Enable Chip Select */
143	hw->pc_en = idx;
144	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
145	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_en | clk;
146
147	/* Reads and writes need to be split for bpw > 16 */
148	topbits = (bpw > 16) ? 16 : bpw;
149	botbits = bpw - topbits;
150
151	/* Write */
152	hw->pc_wr = idx;
153	seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
154	if (botbits)
155		seqram[idx++] = __SHIFT_OUT(botbits)  | SSP_DATA_REG;
156	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
157
158	/* Read */
159	hw->pc_rd = idx;
160	if (botbits)
161		seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
162	seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
163	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
164
165	error = ti_ssp_load(hw->dev, 0, seqram, idx);
166	if (error < 0)
167		return error;
168
169	error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
170					  0 : SSP_EARLY_DIN));
171	if (error < 0)
172		return error;
173
174	hw->bpw = bpw;
175	hw->mode = mode;
176
177	return error;
178}
179
180static void ti_ssp_spi_work(struct work_struct *work)
181{
182	struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
183
184	spin_lock(&hw->lock);
185
186	 while (!list_empty(&hw->msg_queue)) {
187		struct spi_message	*m;
188		struct spi_device	*spi;
189		struct spi_transfer	*t = NULL;
190		int			status = 0;
191
192		m = container_of(hw->msg_queue.next, struct spi_message,
193				 queue);
194
195		list_del_init(&m->queue);
196
197		spin_unlock(&hw->lock);
198
199		spi = m->spi;
200
201		if (hw->select)
202			hw->select(spi->chip_select);
203
204		list_for_each_entry(t, &m->transfers, transfer_list) {
205			int bpw = spi->bits_per_word;
206			int xfer_status;
207
208			if (t->bits_per_word)
209				bpw = t->bits_per_word;
210
211			if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
212				break;
213
214			ti_ssp_spi_chip_select(hw, 1);
215
216			xfer_status = ti_ssp_spi_txrx(hw, m, t);
217			if (xfer_status < 0)
218				status = xfer_status;
219
220			if (t->delay_usecs)
221				udelay(t->delay_usecs);
222
223			if (t->cs_change)
224				ti_ssp_spi_chip_select(hw, 0);
225		}
226
227		ti_ssp_spi_chip_select(hw, 0);
228		m->status = status;
229		m->complete(m->context);
230
231		spin_lock(&hw->lock);
232	}
233
234	if (hw->shutdown)
235		complete(&hw->complete);
236
237	spin_unlock(&hw->lock);
238}
239
240static int ti_ssp_spi_setup(struct spi_device *spi)
241{
242	if (spi->bits_per_word > 32)
243		return -EINVAL;
244
245	return 0;
246}
247
248static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
249{
250	struct ti_ssp_spi	*hw;
251	struct spi_transfer	*t;
252	int			error = 0;
253
254	m->actual_length = 0;
255	m->status = -EINPROGRESS;
256
257	hw = spi_master_get_devdata(spi->master);
258
259	if (list_empty(&m->transfers) || !m->complete)
260		return -EINVAL;
261
262	list_for_each_entry(t, &m->transfers, transfer_list) {
263		if (t->len && !(t->rx_buf || t->tx_buf)) {
264			dev_err(&spi->dev, "invalid xfer, no buffer\n");
265			return -EINVAL;
266		}
267
268		if (t->len && t->rx_buf && t->tx_buf) {
269			dev_err(&spi->dev, "invalid xfer, full duplex\n");
270			return -EINVAL;
271		}
272
273		if (t->bits_per_word > 32) {
274			dev_err(&spi->dev, "invalid xfer width %d\n",
275				t->bits_per_word);
276			return -EINVAL;
277		}
278	}
279
280	spin_lock(&hw->lock);
281	if (hw->shutdown) {
282		error = -ESHUTDOWN;
283		goto error_unlock;
284	}
285	list_add_tail(&m->queue, &hw->msg_queue);
286	queue_work(hw->workqueue, &hw->work);
287error_unlock:
288	spin_unlock(&hw->lock);
289	return error;
290}
291
292static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
293{
294	const struct ti_ssp_spi_data *pdata;
295	struct ti_ssp_spi *hw;
296	struct spi_master *master;
297	struct device *dev = &pdev->dev;
298	int error = 0;
299
300	pdata = dev->platform_data;
301	if (!pdata) {
302		dev_err(dev, "platform data not found\n");
303		return -EINVAL;
304	}
305
306	master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
307	if (!master) {
308		dev_err(dev, "cannot allocate SPI master\n");
309		return -ENOMEM;
310	}
311
312	hw = spi_master_get_devdata(master);
313	platform_set_drvdata(pdev, hw);
314
315	hw->master = master;
316	hw->dev = dev;
317	hw->select = pdata->select;
318
319	spin_lock_init(&hw->lock);
320	init_completion(&hw->complete);
321	INIT_LIST_HEAD(&hw->msg_queue);
322	INIT_WORK(&hw->work, ti_ssp_spi_work);
323
324	hw->workqueue = create_singlethread_workqueue(dev_name(dev));
325	if (!hw->workqueue) {
326		error = -ENOMEM;
327		dev_err(dev, "work queue creation failed\n");
328		goto error_wq;
329	}
330
331	error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
332	if (error < 0) {
333		dev_err(dev, "io setup failed\n");
334		goto error_iosel;
335	}
336
337	master->bus_num		= pdev->id;
338	master->num_chipselect	= pdata->num_cs;
339	master->mode_bits	= MODE_BITS;
340	master->flags		= SPI_MASTER_HALF_DUPLEX;
341	master->setup		= ti_ssp_spi_setup;
342	master->transfer	= ti_ssp_spi_transfer;
343
344	error = spi_register_master(master);
345	if (error) {
346		dev_err(dev, "master registration failed\n");
347		goto error_reg;
348	}
349
350	return 0;
351
352error_reg:
353error_iosel:
354	destroy_workqueue(hw->workqueue);
355error_wq:
356	spi_master_put(master);
357	return error;
358}
359
360static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
361{
362	struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
363	int error;
364
365	hw->shutdown = 1;
366	while (!list_empty(&hw->msg_queue)) {
367		error = wait_for_completion_interruptible(&hw->complete);
368		if (error < 0) {
369			hw->shutdown = 0;
370			return error;
371		}
372	}
373	destroy_workqueue(hw->workqueue);
374	spi_unregister_master(hw->master);
375
376	return 0;
377}
378
379static struct platform_driver ti_ssp_spi_driver = {
380	.probe		= ti_ssp_spi_probe,
381	.remove		= __devexit_p(ti_ssp_spi_remove),
382	.driver		= {
383		.name	= "ti-ssp-spi",
384		.owner	= THIS_MODULE,
385	},
386};
387module_platform_driver(ti_ssp_spi_driver);
388
389MODULE_DESCRIPTION("SSP SPI Master");
390MODULE_AUTHOR("Cyril Chemparathy");
391MODULE_LICENSE("GPL");
392MODULE_ALIAS("platform:ti-ssp-spi");