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1/*
2 * SPI master driver using generic bitbanged GPIO
3 *
4 * Copyright (C) 2006,2008 David Brownell
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., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20#include <linux/kernel.h>
21#include <linux/init.h>
22#include <linux/platform_device.h>
23#include <linux/gpio.h>
24
25#include <linux/spi/spi.h>
26#include <linux/spi/spi_bitbang.h>
27#include <linux/spi/spi_gpio.h>
28
29
30/*
31 * This bitbanging SPI master driver should help make systems usable
32 * when a native hardware SPI engine is not available, perhaps because
33 * its driver isn't yet working or because the I/O pins it requires
34 * are used for other purposes.
35 *
36 * platform_device->driver_data ... points to spi_gpio
37 *
38 * spi->controller_state ... reserved for bitbang framework code
39 * spi->controller_data ... holds chipselect GPIO
40 *
41 * spi->master->dev.driver_data ... points to spi_gpio->bitbang
42 */
43
44struct spi_gpio {
45 struct spi_bitbang bitbang;
46 struct spi_gpio_platform_data pdata;
47 struct platform_device *pdev;
48};
49
50/*----------------------------------------------------------------------*/
51
52/*
53 * Because the overhead of going through four GPIO procedure calls
54 * per transferred bit can make performance a problem, this code
55 * is set up so that you can use it in either of two ways:
56 *
57 * - The slow generic way: set up platform_data to hold the GPIO
58 * numbers used for MISO/MOSI/SCK, and issue procedure calls for
59 * each of them. This driver can handle several such busses.
60 *
61 * - The quicker inlined way: only helps with platform GPIO code
62 * that inlines operations for constant GPIOs. This can give
63 * you tight (fast!) inner loops, but each such bus needs a
64 * new driver. You'll define a new C file, with Makefile and
65 * Kconfig support; the C code can be a total of six lines:
66 *
67 * #define DRIVER_NAME "myboard_spi2"
68 * #define SPI_MISO_GPIO 119
69 * #define SPI_MOSI_GPIO 120
70 * #define SPI_SCK_GPIO 121
71 * #define SPI_N_CHIPSEL 4
72 * #include "spi-gpio.c"
73 */
74
75#ifndef DRIVER_NAME
76#define DRIVER_NAME "spi_gpio"
77
78#define GENERIC_BITBANG /* vs tight inlines */
79
80/* all functions referencing these symbols must define pdata */
81#define SPI_MISO_GPIO ((pdata)->miso)
82#define SPI_MOSI_GPIO ((pdata)->mosi)
83#define SPI_SCK_GPIO ((pdata)->sck)
84
85#define SPI_N_CHIPSEL ((pdata)->num_chipselect)
86
87#endif
88
89/*----------------------------------------------------------------------*/
90
91static inline const struct spi_gpio_platform_data * __pure
92spi_to_pdata(const struct spi_device *spi)
93{
94 const struct spi_bitbang *bang;
95 const struct spi_gpio *spi_gpio;
96
97 bang = spi_master_get_devdata(spi->master);
98 spi_gpio = container_of(bang, struct spi_gpio, bitbang);
99 return &spi_gpio->pdata;
100}
101
102/* this is #defined to avoid unused-variable warnings when inlining */
103#define pdata spi_to_pdata(spi)
104
105static inline void setsck(const struct spi_device *spi, int is_on)
106{
107 gpio_set_value(SPI_SCK_GPIO, is_on);
108}
109
110static inline void setmosi(const struct spi_device *spi, int is_on)
111{
112 gpio_set_value(SPI_MOSI_GPIO, is_on);
113}
114
115static inline int getmiso(const struct spi_device *spi)
116{
117 return !!gpio_get_value(SPI_MISO_GPIO);
118}
119
120#undef pdata
121
122/*
123 * NOTE: this clocks "as fast as we can". It "should" be a function of the
124 * requested device clock. Software overhead means we usually have trouble
125 * reaching even one Mbit/sec (except when we can inline bitops), so for now
126 * we'll just assume we never need additional per-bit slowdowns.
127 */
128#define spidelay(nsecs) do {} while (0)
129
130#include "spi-bitbang-txrx.h"
131
132/*
133 * These functions can leverage inline expansion of GPIO calls to shrink
134 * costs for a txrx bit, often by factors of around ten (by instruction
135 * count). That is particularly visible for larger word sizes, but helps
136 * even with default 8-bit words.
137 *
138 * REVISIT overheads calling these functions for each word also have
139 * significant performance costs. Having txrx_bufs() calls that inline
140 * the txrx_word() logic would help performance, e.g. on larger blocks
141 * used with flash storage or MMC/SD. There should also be ways to make
142 * GCC be less stupid about reloading registers inside the I/O loops,
143 * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
144 */
145
146static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
147 unsigned nsecs, u32 word, u8 bits)
148{
149 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
150}
151
152static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
153 unsigned nsecs, u32 word, u8 bits)
154{
155 return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
156}
157
158static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
159 unsigned nsecs, u32 word, u8 bits)
160{
161 return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
162}
163
164static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
165 unsigned nsecs, u32 word, u8 bits)
166{
167 return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
168}
169
170/*
171 * These functions do not call setmosi or getmiso if respective flag
172 * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
173 * call when such pin is not present or defined in the controller.
174 * A separate set of callbacks is defined to get highest possible
175 * speed in the generic case (when both MISO and MOSI lines are
176 * available), as optimiser will remove the checks when argument is
177 * constant.
178 */
179
180static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
181 unsigned nsecs, u32 word, u8 bits)
182{
183 unsigned flags = spi->master->flags;
184 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
185}
186
187static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
188 unsigned nsecs, u32 word, u8 bits)
189{
190 unsigned flags = spi->master->flags;
191 return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
192}
193
194static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
195 unsigned nsecs, u32 word, u8 bits)
196{
197 unsigned flags = spi->master->flags;
198 return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
199}
200
201static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
202 unsigned nsecs, u32 word, u8 bits)
203{
204 unsigned flags = spi->master->flags;
205 return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
206}
207
208/*----------------------------------------------------------------------*/
209
210static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
211{
212 unsigned long cs = (unsigned long) spi->controller_data;
213
214 /* set initial clock polarity */
215 if (is_active)
216 setsck(spi, spi->mode & SPI_CPOL);
217
218 if (cs != SPI_GPIO_NO_CHIPSELECT) {
219 /* SPI is normally active-low */
220 gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
221 }
222}
223
224static int spi_gpio_setup(struct spi_device *spi)
225{
226 unsigned long cs = (unsigned long) spi->controller_data;
227 int status = 0;
228
229 if (spi->bits_per_word > 32)
230 return -EINVAL;
231
232 if (!spi->controller_state) {
233 if (cs != SPI_GPIO_NO_CHIPSELECT) {
234 status = gpio_request(cs, dev_name(&spi->dev));
235 if (status)
236 return status;
237 status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
238 }
239 }
240 if (!status)
241 status = spi_bitbang_setup(spi);
242 if (status) {
243 if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
244 gpio_free(cs);
245 }
246 return status;
247}
248
249static void spi_gpio_cleanup(struct spi_device *spi)
250{
251 unsigned long cs = (unsigned long) spi->controller_data;
252
253 if (cs != SPI_GPIO_NO_CHIPSELECT)
254 gpio_free(cs);
255 spi_bitbang_cleanup(spi);
256}
257
258static int __init spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
259{
260 int value;
261
262 value = gpio_request(pin, label);
263 if (value == 0) {
264 if (is_in)
265 value = gpio_direction_input(pin);
266 else
267 value = gpio_direction_output(pin, 0);
268 }
269 return value;
270}
271
272static int __init
273spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label,
274 u16 *res_flags)
275{
276 int value;
277
278 /* NOTE: SPI_*_GPIO symbols may reference "pdata" */
279
280 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
281 value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
282 if (value)
283 goto done;
284 } else {
285 /* HW configuration without MOSI pin */
286 *res_flags |= SPI_MASTER_NO_TX;
287 }
288
289 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
290 value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
291 if (value)
292 goto free_mosi;
293 } else {
294 /* HW configuration without MISO pin */
295 *res_flags |= SPI_MASTER_NO_RX;
296 }
297
298 value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
299 if (value)
300 goto free_miso;
301
302 goto done;
303
304free_miso:
305 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
306 gpio_free(SPI_MISO_GPIO);
307free_mosi:
308 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
309 gpio_free(SPI_MOSI_GPIO);
310done:
311 return value;
312}
313
314static int __init spi_gpio_probe(struct platform_device *pdev)
315{
316 int status;
317 struct spi_master *master;
318 struct spi_gpio *spi_gpio;
319 struct spi_gpio_platform_data *pdata;
320 u16 master_flags = 0;
321
322 pdata = pdev->dev.platform_data;
323#ifdef GENERIC_BITBANG
324 if (!pdata || !pdata->num_chipselect)
325 return -ENODEV;
326#endif
327
328 status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
329 if (status < 0)
330 return status;
331
332 master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio);
333 if (!master) {
334 status = -ENOMEM;
335 goto gpio_free;
336 }
337 spi_gpio = spi_master_get_devdata(master);
338 platform_set_drvdata(pdev, spi_gpio);
339
340 spi_gpio->pdev = pdev;
341 if (pdata)
342 spi_gpio->pdata = *pdata;
343
344 master->flags = master_flags;
345 master->bus_num = pdev->id;
346 master->num_chipselect = SPI_N_CHIPSEL;
347 master->setup = spi_gpio_setup;
348 master->cleanup = spi_gpio_cleanup;
349
350 spi_gpio->bitbang.master = spi_master_get(master);
351 spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
352
353 if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
354 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
355 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
356 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
357 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
358 } else {
359 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
360 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
361 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
362 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
363 }
364 spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
365 spi_gpio->bitbang.flags = SPI_CS_HIGH;
366
367 status = spi_bitbang_start(&spi_gpio->bitbang);
368 if (status < 0) {
369 spi_master_put(spi_gpio->bitbang.master);
370gpio_free:
371 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
372 gpio_free(SPI_MISO_GPIO);
373 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
374 gpio_free(SPI_MOSI_GPIO);
375 gpio_free(SPI_SCK_GPIO);
376 spi_master_put(master);
377 }
378
379 return status;
380}
381
382static int __exit spi_gpio_remove(struct platform_device *pdev)
383{
384 struct spi_gpio *spi_gpio;
385 struct spi_gpio_platform_data *pdata;
386 int status;
387
388 spi_gpio = platform_get_drvdata(pdev);
389 pdata = pdev->dev.platform_data;
390
391 /* stop() unregisters child devices too */
392 status = spi_bitbang_stop(&spi_gpio->bitbang);
393 spi_master_put(spi_gpio->bitbang.master);
394
395 platform_set_drvdata(pdev, NULL);
396
397 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
398 gpio_free(SPI_MISO_GPIO);
399 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
400 gpio_free(SPI_MOSI_GPIO);
401 gpio_free(SPI_SCK_GPIO);
402
403 return status;
404}
405
406MODULE_ALIAS("platform:" DRIVER_NAME);
407
408static struct platform_driver spi_gpio_driver = {
409 .driver.name = DRIVER_NAME,
410 .driver.owner = THIS_MODULE,
411 .remove = __exit_p(spi_gpio_remove),
412};
413
414static int __init spi_gpio_init(void)
415{
416 return platform_driver_probe(&spi_gpio_driver, spi_gpio_probe);
417}
418module_init(spi_gpio_init);
419
420static void __exit spi_gpio_exit(void)
421{
422 platform_driver_unregister(&spi_gpio_driver);
423}
424module_exit(spi_gpio_exit);
425
426
427MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
428MODULE_AUTHOR("David Brownell");
429MODULE_LICENSE("GPL");
1/*
2 * SPI master driver using generic bitbanged GPIO
3 *
4 * Copyright (C) 2006,2008 David Brownell
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., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/init.h>
23#include <linux/platform_device.h>
24#include <linux/gpio.h>
25
26#include <linux/spi/spi.h>
27#include <linux/spi/spi_bitbang.h>
28#include <linux/spi/spi_gpio.h>
29
30
31/*
32 * This bitbanging SPI master driver should help make systems usable
33 * when a native hardware SPI engine is not available, perhaps because
34 * its driver isn't yet working or because the I/O pins it requires
35 * are used for other purposes.
36 *
37 * platform_device->driver_data ... points to spi_gpio
38 *
39 * spi->controller_state ... reserved for bitbang framework code
40 * spi->controller_data ... holds chipselect GPIO
41 *
42 * spi->master->dev.driver_data ... points to spi_gpio->bitbang
43 */
44
45struct spi_gpio {
46 struct spi_bitbang bitbang;
47 struct spi_gpio_platform_data pdata;
48 struct platform_device *pdev;
49};
50
51/*----------------------------------------------------------------------*/
52
53/*
54 * Because the overhead of going through four GPIO procedure calls
55 * per transferred bit can make performance a problem, this code
56 * is set up so that you can use it in either of two ways:
57 *
58 * - The slow generic way: set up platform_data to hold the GPIO
59 * numbers used for MISO/MOSI/SCK, and issue procedure calls for
60 * each of them. This driver can handle several such busses.
61 *
62 * - The quicker inlined way: only helps with platform GPIO code
63 * that inlines operations for constant GPIOs. This can give
64 * you tight (fast!) inner loops, but each such bus needs a
65 * new driver. You'll define a new C file, with Makefile and
66 * Kconfig support; the C code can be a total of six lines:
67 *
68 * #define DRIVER_NAME "myboard_spi2"
69 * #define SPI_MISO_GPIO 119
70 * #define SPI_MOSI_GPIO 120
71 * #define SPI_SCK_GPIO 121
72 * #define SPI_N_CHIPSEL 4
73 * #include "spi-gpio.c"
74 */
75
76#ifndef DRIVER_NAME
77#define DRIVER_NAME "spi_gpio"
78
79#define GENERIC_BITBANG /* vs tight inlines */
80
81/* all functions referencing these symbols must define pdata */
82#define SPI_MISO_GPIO ((pdata)->miso)
83#define SPI_MOSI_GPIO ((pdata)->mosi)
84#define SPI_SCK_GPIO ((pdata)->sck)
85
86#define SPI_N_CHIPSEL ((pdata)->num_chipselect)
87
88#endif
89
90/*----------------------------------------------------------------------*/
91
92static inline const struct spi_gpio_platform_data * __pure
93spi_to_pdata(const struct spi_device *spi)
94{
95 const struct spi_bitbang *bang;
96 const struct spi_gpio *spi_gpio;
97
98 bang = spi_master_get_devdata(spi->master);
99 spi_gpio = container_of(bang, struct spi_gpio, bitbang);
100 return &spi_gpio->pdata;
101}
102
103/* this is #defined to avoid unused-variable warnings when inlining */
104#define pdata spi_to_pdata(spi)
105
106static inline void setsck(const struct spi_device *spi, int is_on)
107{
108 gpio_set_value(SPI_SCK_GPIO, is_on);
109}
110
111static inline void setmosi(const struct spi_device *spi, int is_on)
112{
113 gpio_set_value(SPI_MOSI_GPIO, is_on);
114}
115
116static inline int getmiso(const struct spi_device *spi)
117{
118 return !!gpio_get_value(SPI_MISO_GPIO);
119}
120
121#undef pdata
122
123/*
124 * NOTE: this clocks "as fast as we can". It "should" be a function of the
125 * requested device clock. Software overhead means we usually have trouble
126 * reaching even one Mbit/sec (except when we can inline bitops), so for now
127 * we'll just assume we never need additional per-bit slowdowns.
128 */
129#define spidelay(nsecs) do {} while (0)
130
131#include "spi-bitbang-txrx.h"
132
133/*
134 * These functions can leverage inline expansion of GPIO calls to shrink
135 * costs for a txrx bit, often by factors of around ten (by instruction
136 * count). That is particularly visible for larger word sizes, but helps
137 * even with default 8-bit words.
138 *
139 * REVISIT overheads calling these functions for each word also have
140 * significant performance costs. Having txrx_bufs() calls that inline
141 * the txrx_word() logic would help performance, e.g. on larger blocks
142 * used with flash storage or MMC/SD. There should also be ways to make
143 * GCC be less stupid about reloading registers inside the I/O loops,
144 * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
145 */
146
147static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
148 unsigned nsecs, u32 word, u8 bits)
149{
150 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
151}
152
153static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
154 unsigned nsecs, u32 word, u8 bits)
155{
156 return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
157}
158
159static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
160 unsigned nsecs, u32 word, u8 bits)
161{
162 return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
163}
164
165static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
166 unsigned nsecs, u32 word, u8 bits)
167{
168 return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
169}
170
171/*
172 * These functions do not call setmosi or getmiso if respective flag
173 * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
174 * call when such pin is not present or defined in the controller.
175 * A separate set of callbacks is defined to get highest possible
176 * speed in the generic case (when both MISO and MOSI lines are
177 * available), as optimiser will remove the checks when argument is
178 * constant.
179 */
180
181static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
182 unsigned nsecs, u32 word, u8 bits)
183{
184 unsigned flags = spi->master->flags;
185 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
186}
187
188static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
189 unsigned nsecs, u32 word, u8 bits)
190{
191 unsigned flags = spi->master->flags;
192 return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
193}
194
195static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
196 unsigned nsecs, u32 word, u8 bits)
197{
198 unsigned flags = spi->master->flags;
199 return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
200}
201
202static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
203 unsigned nsecs, u32 word, u8 bits)
204{
205 unsigned flags = spi->master->flags;
206 return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
207}
208
209/*----------------------------------------------------------------------*/
210
211static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
212{
213 unsigned long cs = (unsigned long) spi->controller_data;
214
215 /* set initial clock polarity */
216 if (is_active)
217 setsck(spi, spi->mode & SPI_CPOL);
218
219 if (cs != SPI_GPIO_NO_CHIPSELECT) {
220 /* SPI is normally active-low */
221 gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
222 }
223}
224
225static int spi_gpio_setup(struct spi_device *spi)
226{
227 unsigned long cs = (unsigned long) spi->controller_data;
228 int status = 0;
229
230 if (spi->bits_per_word > 32)
231 return -EINVAL;
232
233 if (!spi->controller_state) {
234 if (cs != SPI_GPIO_NO_CHIPSELECT) {
235 status = gpio_request(cs, dev_name(&spi->dev));
236 if (status)
237 return status;
238 status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
239 }
240 }
241 if (!status)
242 status = spi_bitbang_setup(spi);
243 if (status) {
244 if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
245 gpio_free(cs);
246 }
247 return status;
248}
249
250static void spi_gpio_cleanup(struct spi_device *spi)
251{
252 unsigned long cs = (unsigned long) spi->controller_data;
253
254 if (cs != SPI_GPIO_NO_CHIPSELECT)
255 gpio_free(cs);
256 spi_bitbang_cleanup(spi);
257}
258
259static int __devinit spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
260{
261 int value;
262
263 value = gpio_request(pin, label);
264 if (value == 0) {
265 if (is_in)
266 value = gpio_direction_input(pin);
267 else
268 value = gpio_direction_output(pin, 0);
269 }
270 return value;
271}
272
273static int __devinit
274spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label,
275 u16 *res_flags)
276{
277 int value;
278
279 /* NOTE: SPI_*_GPIO symbols may reference "pdata" */
280
281 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
282 value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
283 if (value)
284 goto done;
285 } else {
286 /* HW configuration without MOSI pin */
287 *res_flags |= SPI_MASTER_NO_TX;
288 }
289
290 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
291 value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
292 if (value)
293 goto free_mosi;
294 } else {
295 /* HW configuration without MISO pin */
296 *res_flags |= SPI_MASTER_NO_RX;
297 }
298
299 value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
300 if (value)
301 goto free_miso;
302
303 goto done;
304
305free_miso:
306 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
307 gpio_free(SPI_MISO_GPIO);
308free_mosi:
309 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
310 gpio_free(SPI_MOSI_GPIO);
311done:
312 return value;
313}
314
315static int __devinit spi_gpio_probe(struct platform_device *pdev)
316{
317 int status;
318 struct spi_master *master;
319 struct spi_gpio *spi_gpio;
320 struct spi_gpio_platform_data *pdata;
321 u16 master_flags = 0;
322
323 pdata = pdev->dev.platform_data;
324#ifdef GENERIC_BITBANG
325 if (!pdata || !pdata->num_chipselect)
326 return -ENODEV;
327#endif
328
329 status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
330 if (status < 0)
331 return status;
332
333 master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio);
334 if (!master) {
335 status = -ENOMEM;
336 goto gpio_free;
337 }
338 spi_gpio = spi_master_get_devdata(master);
339 platform_set_drvdata(pdev, spi_gpio);
340
341 spi_gpio->pdev = pdev;
342 if (pdata)
343 spi_gpio->pdata = *pdata;
344
345 master->flags = master_flags;
346 master->bus_num = pdev->id;
347 master->num_chipselect = SPI_N_CHIPSEL;
348 master->setup = spi_gpio_setup;
349 master->cleanup = spi_gpio_cleanup;
350
351 spi_gpio->bitbang.master = spi_master_get(master);
352 spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
353
354 if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
355 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
356 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
357 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
358 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
359 } else {
360 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
361 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
362 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
363 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
364 }
365 spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
366 spi_gpio->bitbang.flags = SPI_CS_HIGH;
367
368 status = spi_bitbang_start(&spi_gpio->bitbang);
369 if (status < 0) {
370 spi_master_put(spi_gpio->bitbang.master);
371gpio_free:
372 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
373 gpio_free(SPI_MISO_GPIO);
374 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
375 gpio_free(SPI_MOSI_GPIO);
376 gpio_free(SPI_SCK_GPIO);
377 spi_master_put(master);
378 }
379
380 return status;
381}
382
383static int __devexit spi_gpio_remove(struct platform_device *pdev)
384{
385 struct spi_gpio *spi_gpio;
386 struct spi_gpio_platform_data *pdata;
387 int status;
388
389 spi_gpio = platform_get_drvdata(pdev);
390 pdata = pdev->dev.platform_data;
391
392 /* stop() unregisters child devices too */
393 status = spi_bitbang_stop(&spi_gpio->bitbang);
394 spi_master_put(spi_gpio->bitbang.master);
395
396 platform_set_drvdata(pdev, NULL);
397
398 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
399 gpio_free(SPI_MISO_GPIO);
400 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
401 gpio_free(SPI_MOSI_GPIO);
402 gpio_free(SPI_SCK_GPIO);
403
404 return status;
405}
406
407MODULE_ALIAS("platform:" DRIVER_NAME);
408
409static struct platform_driver spi_gpio_driver = {
410 .driver.name = DRIVER_NAME,
411 .driver.owner = THIS_MODULE,
412 .probe = spi_gpio_probe,
413 .remove = __devexit_p(spi_gpio_remove),
414};
415module_platform_driver(spi_gpio_driver);
416
417MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
418MODULE_AUTHOR("David Brownell");
419MODULE_LICENSE("GPL");