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a72aeefe CC |
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> | |
d7614de4 | 25 | #include <linux/module.h> |
a72aeefe CC |
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
a72aeefe CC |
240 | static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m) |
241 | { | |
242 | struct ti_ssp_spi *hw; | |
243 | struct spi_transfer *t; | |
244 | int error = 0; | |
245 | ||
246 | m->actual_length = 0; | |
247 | m->status = -EINPROGRESS; | |
248 | ||
249 | hw = spi_master_get_devdata(spi->master); | |
250 | ||
251 | if (list_empty(&m->transfers) || !m->complete) | |
252 | return -EINVAL; | |
253 | ||
254 | list_for_each_entry(t, &m->transfers, transfer_list) { | |
255 | if (t->len && !(t->rx_buf || t->tx_buf)) { | |
256 | dev_err(&spi->dev, "invalid xfer, no buffer\n"); | |
257 | return -EINVAL; | |
258 | } | |
259 | ||
260 | if (t->len && t->rx_buf && t->tx_buf) { | |
261 | dev_err(&spi->dev, "invalid xfer, full duplex\n"); | |
262 | return -EINVAL; | |
263 | } | |
a72aeefe CC |
264 | } |
265 | ||
266 | spin_lock(&hw->lock); | |
267 | if (hw->shutdown) { | |
268 | error = -ESHUTDOWN; | |
269 | goto error_unlock; | |
270 | } | |
271 | list_add_tail(&m->queue, &hw->msg_queue); | |
272 | queue_work(hw->workqueue, &hw->work); | |
273 | error_unlock: | |
274 | spin_unlock(&hw->lock); | |
275 | return error; | |
276 | } | |
277 | ||
fd4a319b | 278 | static int ti_ssp_spi_probe(struct platform_device *pdev) |
a72aeefe CC |
279 | { |
280 | const struct ti_ssp_spi_data *pdata; | |
281 | struct ti_ssp_spi *hw; | |
282 | struct spi_master *master; | |
283 | struct device *dev = &pdev->dev; | |
284 | int error = 0; | |
285 | ||
8074cf06 | 286 | pdata = dev_get_platdata(dev); |
a72aeefe CC |
287 | if (!pdata) { |
288 | dev_err(dev, "platform data not found\n"); | |
289 | return -EINVAL; | |
290 | } | |
291 | ||
292 | master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi)); | |
293 | if (!master) { | |
294 | dev_err(dev, "cannot allocate SPI master\n"); | |
295 | return -ENOMEM; | |
296 | } | |
297 | ||
298 | hw = spi_master_get_devdata(master); | |
299 | platform_set_drvdata(pdev, hw); | |
300 | ||
301 | hw->master = master; | |
302 | hw->dev = dev; | |
303 | hw->select = pdata->select; | |
304 | ||
305 | spin_lock_init(&hw->lock); | |
306 | init_completion(&hw->complete); | |
307 | INIT_LIST_HEAD(&hw->msg_queue); | |
308 | INIT_WORK(&hw->work, ti_ssp_spi_work); | |
309 | ||
310 | hw->workqueue = create_singlethread_workqueue(dev_name(dev)); | |
311 | if (!hw->workqueue) { | |
312 | error = -ENOMEM; | |
313 | dev_err(dev, "work queue creation failed\n"); | |
314 | goto error_wq; | |
315 | } | |
316 | ||
317 | error = ti_ssp_set_iosel(hw->dev, pdata->iosel); | |
318 | if (error < 0) { | |
319 | dev_err(dev, "io setup failed\n"); | |
320 | goto error_iosel; | |
321 | } | |
322 | ||
323 | master->bus_num = pdev->id; | |
324 | master->num_chipselect = pdata->num_cs; | |
325 | master->mode_bits = MODE_BITS; | |
24778be2 | 326 | master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32); |
a72aeefe | 327 | master->flags = SPI_MASTER_HALF_DUPLEX; |
a72aeefe CC |
328 | master->transfer = ti_ssp_spi_transfer; |
329 | ||
330 | error = spi_register_master(master); | |
331 | if (error) { | |
332 | dev_err(dev, "master registration failed\n"); | |
333 | goto error_reg; | |
334 | } | |
335 | ||
336 | return 0; | |
337 | ||
338 | error_reg: | |
339 | error_iosel: | |
340 | destroy_workqueue(hw->workqueue); | |
341 | error_wq: | |
342 | spi_master_put(master); | |
343 | return error; | |
344 | } | |
345 | ||
fd4a319b | 346 | static int ti_ssp_spi_remove(struct platform_device *pdev) |
a72aeefe CC |
347 | { |
348 | struct ti_ssp_spi *hw = platform_get_drvdata(pdev); | |
349 | int error; | |
350 | ||
351 | hw->shutdown = 1; | |
352 | while (!list_empty(&hw->msg_queue)) { | |
353 | error = wait_for_completion_interruptible(&hw->complete); | |
354 | if (error < 0) { | |
355 | hw->shutdown = 0; | |
356 | return error; | |
357 | } | |
358 | } | |
359 | destroy_workqueue(hw->workqueue); | |
360 | spi_unregister_master(hw->master); | |
361 | ||
362 | return 0; | |
363 | } | |
364 | ||
365 | static struct platform_driver ti_ssp_spi_driver = { | |
366 | .probe = ti_ssp_spi_probe, | |
fd4a319b | 367 | .remove = ti_ssp_spi_remove, |
a72aeefe CC |
368 | .driver = { |
369 | .name = "ti-ssp-spi", | |
370 | .owner = THIS_MODULE, | |
371 | }, | |
372 | }; | |
940ab889 | 373 | module_platform_driver(ti_ssp_spi_driver); |
a72aeefe CC |
374 | |
375 | MODULE_DESCRIPTION("SSP SPI Master"); | |
376 | MODULE_AUTHOR("Cyril Chemparathy"); | |
377 | MODULE_LICENSE("GPL"); | |
378 | MODULE_ALIAS("platform:ti-ssp-spi"); |