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
32 struct 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
ti_ssp_spi_rx(struct ti_ssp_spi * hw)47 static 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
ti_ssp_spi_tx(struct ti_ssp_spi * hw,u32 data)55 static 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
ti_ssp_spi_txrx(struct ti_ssp_spi * hw,struct spi_message * msg,struct spi_transfer * t)60 static 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
ti_ssp_spi_chip_select(struct ti_ssp_spi * hw,int cs_active)106 static 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
ti_ssp_spi_setup_transfer(struct ti_ssp_spi * hw,u8 bpw,u8 mode)120 static 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
ti_ssp_spi_work(struct work_struct * work)180 static 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
ti_ssp_spi_setup(struct spi_device * spi)240 static 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
ti_ssp_spi_transfer(struct spi_device * spi,struct spi_message * m)248 static 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);
287 error_unlock:
288 spin_unlock(&hw->lock);
289 return error;
290 }
291
ti_ssp_spi_probe(struct platform_device * pdev)292 static 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
352 error_reg:
353 error_iosel:
354 destroy_workqueue(hw->workqueue);
355 error_wq:
356 spi_master_put(master);
357 return error;
358 }
359
ti_ssp_spi_remove(struct platform_device * pdev)360 static 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
379 static 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 };
387 module_platform_driver(ti_ssp_spi_driver);
388
389 MODULE_DESCRIPTION("SSP SPI Master");
390 MODULE_AUTHOR("Cyril Chemparathy");
391 MODULE_LICENSE("GPL");
392 MODULE_ALIAS("platform:ti-ssp-spi");
393