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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 | ||
31 | struct 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 | ||
46 | static 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 | ||
54 | static 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 | ||
59 | static 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 | ||
105 | static 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 | ||
119 | static 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 | ||
179 | static 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 | ||
239 | static 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 | ||
247 | static 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); | |
286 | error_unlock: | |
287 | spin_unlock(&hw->lock); | |
288 | return error; | |
289 | } | |
290 | ||
291 | static 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 | ||
351 | error_reg: | |
352 | error_iosel: | |
353 | destroy_workqueue(hw->workqueue); | |
354 | error_wq: | |
355 | spi_master_put(master); | |
356 | return error; | |
357 | } | |
358 | ||
359 | static 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 | ||
378 | static 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 | ||
387 | static int __init ti_ssp_spi_init(void) | |
388 | { | |
389 | return platform_driver_register(&ti_ssp_spi_driver); | |
390 | } | |
391 | module_init(ti_ssp_spi_init); | |
392 | ||
393 | static void __exit ti_ssp_spi_exit(void) | |
394 | { | |
395 | platform_driver_unregister(&ti_ssp_spi_driver); | |
396 | } | |
397 | module_exit(ti_ssp_spi_exit); | |
398 | ||
399 | MODULE_DESCRIPTION("SSP SPI Master"); | |
400 | MODULE_AUTHOR("Cyril Chemparathy"); | |
401 | MODULE_LICENSE("GPL"); | |
402 | MODULE_ALIAS("platform:ti-ssp-spi"); |