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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * SPI host driver using generic bitbanged GPIO
4 *
5 * Copyright (C) 2006,2008 David Brownell
6 * Copyright (C) 2017 Linus Walleij
7 */
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/platform_device.h>
11#include <linux/gpio/consumer.h>
12#include <linux/of.h>
13
14#include <linux/spi/spi.h>
15#include <linux/spi/spi_bitbang.h>
16#include <linux/spi/spi_gpio.h>
17
18
19/*
20 * This bitbanging SPI host driver should help make systems usable
21 * when a native hardware SPI engine is not available, perhaps because
22 * its driver isn't yet working or because the I/O pins it requires
23 * are used for other purposes.
24 *
25 * platform_device->driver_data ... points to spi_gpio
26 *
27 * spi->controller_state ... reserved for bitbang framework code
28 *
29 * spi->controller->dev.driver_data ... points to spi_gpio->bitbang
30 */
31
32struct spi_gpio {
33 struct spi_bitbang bitbang;
34 struct gpio_desc *sck;
35 struct gpio_desc *miso;
36 struct gpio_desc *mosi;
37 struct gpio_desc **cs_gpios;
38};
39
40/*----------------------------------------------------------------------*/
41
42/*
43 * Because the overhead of going through four GPIO procedure calls
44 * per transferred bit can make performance a problem, this code
45 * is set up so that you can use it in either of two ways:
46 *
47 * - The slow generic way: set up platform_data to hold the GPIO
48 * numbers used for MISO/MOSI/SCK, and issue procedure calls for
49 * each of them. This driver can handle several such busses.
50 *
51 * - The quicker inlined way: only helps with platform GPIO code
52 * that inlines operations for constant GPIOs. This can give
53 * you tight (fast!) inner loops, but each such bus needs a
54 * new driver. You'll define a new C file, with Makefile and
55 * Kconfig support; the C code can be a total of six lines:
56 *
57 * #define DRIVER_NAME "myboard_spi2"
58 * #define SPI_MISO_GPIO 119
59 * #define SPI_MOSI_GPIO 120
60 * #define SPI_SCK_GPIO 121
61 * #define SPI_N_CHIPSEL 4
62 * #include "spi-gpio.c"
63 */
64
65#ifndef DRIVER_NAME
66#define DRIVER_NAME "spi_gpio"
67
68#define GENERIC_BITBANG /* vs tight inlines */
69
70#endif
71
72/*----------------------------------------------------------------------*/
73
74static inline struct spi_gpio *__pure
75spi_to_spi_gpio(const struct spi_device *spi)
76{
77 const struct spi_bitbang *bang;
78 struct spi_gpio *spi_gpio;
79
80 bang = spi_controller_get_devdata(spi->controller);
81 spi_gpio = container_of(bang, struct spi_gpio, bitbang);
82 return spi_gpio;
83}
84
85/* These helpers are in turn called by the bitbang inlines */
86static inline void setsck(const struct spi_device *spi, int is_on)
87{
88 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
89
90 gpiod_set_value_cansleep(spi_gpio->sck, is_on);
91}
92
93static inline void setmosi(const struct spi_device *spi, int is_on)
94{
95 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
96
97 gpiod_set_value_cansleep(spi_gpio->mosi, is_on);
98}
99
100static inline int getmiso(const struct spi_device *spi)
101{
102 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
103
104 if (spi->mode & SPI_3WIRE)
105 return !!gpiod_get_value_cansleep(spi_gpio->mosi);
106 else
107 return !!gpiod_get_value_cansleep(spi_gpio->miso);
108}
109
110/*
111 * NOTE: this clocks "as fast as we can". It "should" be a function of the
112 * requested device clock. Software overhead means we usually have trouble
113 * reaching even one Mbit/sec (except when we can inline bitops), so for now
114 * we'll just assume we never need additional per-bit slowdowns.
115 */
116#define spidelay(nsecs) do {} while (0)
117
118#include "spi-bitbang-txrx.h"
119
120/*
121 * These functions can leverage inline expansion of GPIO calls to shrink
122 * costs for a txrx bit, often by factors of around ten (by instruction
123 * count). That is particularly visible for larger word sizes, but helps
124 * even with default 8-bit words.
125 *
126 * REVISIT overheads calling these functions for each word also have
127 * significant performance costs. Having txrx_bufs() calls that inline
128 * the txrx_word() logic would help performance, e.g. on larger blocks
129 * used with flash storage or MMC/SD. There should also be ways to make
130 * GCC be less stupid about reloading registers inside the I/O loops,
131 * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
132 */
133
134static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
135 unsigned nsecs, u32 word, u8 bits, unsigned flags)
136{
137 if (unlikely(spi->mode & SPI_LSB_FIRST))
138 return bitbang_txrx_le_cpha0(spi, nsecs, 0, flags, word, bits);
139 else
140 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
141}
142
143static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
144 unsigned nsecs, u32 word, u8 bits, unsigned flags)
145{
146 if (unlikely(spi->mode & SPI_LSB_FIRST))
147 return bitbang_txrx_le_cpha1(spi, nsecs, 0, flags, word, bits);
148 else
149 return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
150}
151
152static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
153 unsigned nsecs, u32 word, u8 bits, unsigned flags)
154{
155 if (unlikely(spi->mode & SPI_LSB_FIRST))
156 return bitbang_txrx_le_cpha0(spi, nsecs, 1, flags, word, bits);
157 else
158 return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
159}
160
161static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
162 unsigned nsecs, u32 word, u8 bits, unsigned flags)
163{
164 if (unlikely(spi->mode & SPI_LSB_FIRST))
165 return bitbang_txrx_le_cpha1(spi, nsecs, 1, flags, word, bits);
166 else
167 return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
168}
169
170/*
171 * These functions do not call setmosi or getmiso if respective flag
172 * (SPI_CONTROLLER_NO_RX or SPI_CONTROLLER_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, unsigned flags)
182{
183 flags = spi->controller->flags;
184 if (unlikely(spi->mode & SPI_LSB_FIRST))
185 return bitbang_txrx_le_cpha0(spi, nsecs, 0, flags, word, bits);
186 else
187 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
188}
189
190static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
191 unsigned nsecs, u32 word, u8 bits, unsigned flags)
192{
193 flags = spi->controller->flags;
194 if (unlikely(spi->mode & SPI_LSB_FIRST))
195 return bitbang_txrx_le_cpha1(spi, nsecs, 0, flags, word, bits);
196 else
197 return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
198}
199
200static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
201 unsigned nsecs, u32 word, u8 bits, unsigned flags)
202{
203 flags = spi->controller->flags;
204 if (unlikely(spi->mode & SPI_LSB_FIRST))
205 return bitbang_txrx_le_cpha0(spi, nsecs, 1, flags, word, bits);
206 else
207 return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
208}
209
210static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
211 unsigned nsecs, u32 word, u8 bits, unsigned flags)
212{
213 flags = spi->controller->flags;
214 if (unlikely(spi->mode & SPI_LSB_FIRST))
215 return bitbang_txrx_le_cpha1(spi, nsecs, 1, flags, word, bits);
216 else
217 return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
218}
219
220/*----------------------------------------------------------------------*/
221
222static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
223{
224 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
225
226 /* set initial clock line level */
227 if (is_active)
228 gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
229
230 /* Drive chip select line, if we have one */
231 if (spi_gpio->cs_gpios) {
232 struct gpio_desc *cs = spi_gpio->cs_gpios[spi_get_chipselect(spi, 0)];
233
234 /* SPI chip selects are normally active-low */
235 gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
236 }
237}
238
239static int spi_gpio_setup(struct spi_device *spi)
240{
241 struct gpio_desc *cs;
242 int status = 0;
243 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
244
245 /*
246 * The CS GPIOs have already been
247 * initialized from the descriptor lookup.
248 */
249 if (spi_gpio->cs_gpios) {
250 cs = spi_gpio->cs_gpios[spi_get_chipselect(spi, 0)];
251 if (!spi->controller_state && cs)
252 status = gpiod_direction_output(cs,
253 !(spi->mode & SPI_CS_HIGH));
254 }
255
256 if (!status)
257 status = spi_bitbang_setup(spi);
258
259 return status;
260}
261
262static int spi_gpio_set_direction(struct spi_device *spi, bool output)
263{
264 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
265 int ret;
266
267 if (output)
268 return gpiod_direction_output(spi_gpio->mosi, 1);
269
270 /*
271 * Only change MOSI to an input if using 3WIRE mode.
272 * Otherwise, MOSI could be left floating if there is
273 * no pull resistor connected to the I/O pin, or could
274 * be left logic high if there is a pull-up. Transmitting
275 * logic high when only clocking MISO data in can put some
276 * SPI devices in to a bad state.
277 */
278 if (spi->mode & SPI_3WIRE) {
279 ret = gpiod_direction_input(spi_gpio->mosi);
280 if (ret)
281 return ret;
282 }
283 /*
284 * Send a turnaround high impedance cycle when switching
285 * from output to input. Theoretically there should be
286 * a clock delay here, but as has been noted above, the
287 * nsec delay function for bit-banged GPIO is simply
288 * {} because bit-banging just doesn't get fast enough
289 * anyway.
290 */
291 if (spi->mode & SPI_3WIRE_HIZ) {
292 gpiod_set_value_cansleep(spi_gpio->sck,
293 !(spi->mode & SPI_CPOL));
294 gpiod_set_value_cansleep(spi_gpio->sck,
295 !!(spi->mode & SPI_CPOL));
296 }
297 return 0;
298}
299
300static void spi_gpio_cleanup(struct spi_device *spi)
301{
302 spi_bitbang_cleanup(spi);
303}
304
305/*
306 * It can be convenient to use this driver with pins that have alternate
307 * functions associated with a "native" SPI controller if a driver for that
308 * controller is not available, or is missing important functionality.
309 *
310 * On platforms which can do so, configure MISO with a weak pullup unless
311 * there's an external pullup on that signal. That saves power by avoiding
312 * floating signals. (A weak pulldown would save power too, but many
313 * drivers expect to see all-ones data as the no target "response".)
314 */
315static int spi_gpio_request(struct device *dev, struct spi_gpio *spi_gpio)
316{
317 spi_gpio->mosi = devm_gpiod_get_optional(dev, "mosi", GPIOD_OUT_LOW);
318 if (IS_ERR(spi_gpio->mosi))
319 return PTR_ERR(spi_gpio->mosi);
320
321 spi_gpio->miso = devm_gpiod_get_optional(dev, "miso", GPIOD_IN);
322 if (IS_ERR(spi_gpio->miso))
323 return PTR_ERR(spi_gpio->miso);
324
325 spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
326 return PTR_ERR_OR_ZERO(spi_gpio->sck);
327}
328
329#ifdef CONFIG_OF
330static const struct of_device_id spi_gpio_dt_ids[] = {
331 { .compatible = "spi-gpio" },
332 {}
333};
334MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
335
336static int spi_gpio_probe_dt(struct platform_device *pdev,
337 struct spi_controller *host)
338{
339 host->dev.of_node = pdev->dev.of_node;
340 host->use_gpio_descriptors = true;
341
342 return 0;
343}
344#else
345static inline int spi_gpio_probe_dt(struct platform_device *pdev,
346 struct spi_controller *host)
347{
348 return 0;
349}
350#endif
351
352static int spi_gpio_probe_pdata(struct platform_device *pdev,
353 struct spi_controller *host)
354{
355 struct device *dev = &pdev->dev;
356 struct spi_gpio_platform_data *pdata = dev_get_platdata(dev);
357 struct spi_gpio *spi_gpio = spi_controller_get_devdata(host);
358 int i;
359
360#ifdef GENERIC_BITBANG
361 if (!pdata || !pdata->num_chipselect)
362 return -ENODEV;
363#endif
364 /*
365 * The host needs to think there is a chipselect even if not
366 * connected
367 */
368 host->num_chipselect = pdata->num_chipselect ?: 1;
369
370 spi_gpio->cs_gpios = devm_kcalloc(dev, host->num_chipselect,
371 sizeof(*spi_gpio->cs_gpios),
372 GFP_KERNEL);
373 if (!spi_gpio->cs_gpios)
374 return -ENOMEM;
375
376 for (i = 0; i < host->num_chipselect; i++) {
377 spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs", i,
378 GPIOD_OUT_HIGH);
379 if (IS_ERR(spi_gpio->cs_gpios[i]))
380 return PTR_ERR(spi_gpio->cs_gpios[i]);
381 }
382
383 return 0;
384}
385
386static int spi_gpio_probe(struct platform_device *pdev)
387{
388 int status;
389 struct spi_controller *host;
390 struct spi_gpio *spi_gpio;
391 struct device *dev = &pdev->dev;
392 struct spi_bitbang *bb;
393
394 host = devm_spi_alloc_host(dev, sizeof(*spi_gpio));
395 if (!host)
396 return -ENOMEM;
397
398 if (pdev->dev.of_node)
399 status = spi_gpio_probe_dt(pdev, host);
400 else
401 status = spi_gpio_probe_pdata(pdev, host);
402
403 if (status)
404 return status;
405
406 spi_gpio = spi_controller_get_devdata(host);
407
408 status = spi_gpio_request(dev, spi_gpio);
409 if (status)
410 return status;
411
412 host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
413 host->mode_bits = SPI_3WIRE | SPI_3WIRE_HIZ | SPI_CPHA | SPI_CPOL |
414 SPI_CS_HIGH | SPI_LSB_FIRST;
415 if (!spi_gpio->mosi) {
416 /* HW configuration without MOSI pin
417 *
418 * No setting SPI_CONTROLLER_NO_RX here - if there is only
419 * a MOSI pin connected the host can still do RX by
420 * changing the direction of the line.
421 */
422 host->flags = SPI_CONTROLLER_NO_TX;
423 }
424
425 host->bus_num = pdev->id;
426 host->setup = spi_gpio_setup;
427 host->cleanup = spi_gpio_cleanup;
428
429 bb = &spi_gpio->bitbang;
430 bb->master = host;
431 /*
432 * There is some additional business, apart from driving the CS GPIO
433 * line, that we need to do on selection. This makes the local
434 * callback for chipselect always get called.
435 */
436 host->flags |= SPI_CONTROLLER_GPIO_SS;
437 bb->chipselect = spi_gpio_chipselect;
438 bb->set_line_direction = spi_gpio_set_direction;
439
440 if (host->flags & SPI_CONTROLLER_NO_TX) {
441 bb->txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
442 bb->txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
443 bb->txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
444 bb->txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
445 } else {
446 bb->txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
447 bb->txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
448 bb->txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
449 bb->txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
450 }
451 bb->setup_transfer = spi_bitbang_setup_transfer;
452
453 status = spi_bitbang_init(&spi_gpio->bitbang);
454 if (status)
455 return status;
456
457 return devm_spi_register_controller(&pdev->dev, host);
458}
459
460MODULE_ALIAS("platform:" DRIVER_NAME);
461
462static struct platform_driver spi_gpio_driver = {
463 .driver = {
464 .name = DRIVER_NAME,
465 .of_match_table = of_match_ptr(spi_gpio_dt_ids),
466 },
467 .probe = spi_gpio_probe,
468};
469module_platform_driver(spi_gpio_driver);
470
471MODULE_DESCRIPTION("SPI host driver using generic bitbanged GPIO ");
472MODULE_AUTHOR("David Brownell");
473MODULE_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#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/gpio.h>
20#include <linux/of.h>
21#include <linux/of_device.h>
22#include <linux/of_gpio.h>
23
24#include <linux/spi/spi.h>
25#include <linux/spi/spi_bitbang.h>
26#include <linux/spi/spi_gpio.h>
27
28
29/*
30 * This bitbanging SPI master driver should help make systems usable
31 * when a native hardware SPI engine is not available, perhaps because
32 * its driver isn't yet working or because the I/O pins it requires
33 * are used for other purposes.
34 *
35 * platform_device->driver_data ... points to spi_gpio
36 *
37 * spi->controller_state ... reserved for bitbang framework code
38 * spi->controller_data ... holds chipselect GPIO
39 *
40 * spi->master->dev.driver_data ... points to spi_gpio->bitbang
41 */
42
43struct spi_gpio {
44 struct spi_bitbang bitbang;
45 struct spi_gpio_platform_data pdata;
46 struct platform_device *pdev;
47 unsigned long cs_gpios[0];
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 struct spi_gpio *__pure
92spi_to_spi_gpio(const struct spi_device *spi)
93{
94 const struct spi_bitbang *bang;
95 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;
100}
101
102static inline struct spi_gpio_platform_data *__pure
103spi_to_pdata(const struct spi_device *spi)
104{
105 return &spi_to_spi_gpio(spi)->pdata;
106}
107
108/* this is #defined to avoid unused-variable warnings when inlining */
109#define pdata spi_to_pdata(spi)
110
111static inline void setsck(const struct spi_device *spi, int is_on)
112{
113 gpio_set_value_cansleep(SPI_SCK_GPIO, is_on);
114}
115
116static inline void setmosi(const struct spi_device *spi, int is_on)
117{
118 gpio_set_value_cansleep(SPI_MOSI_GPIO, is_on);
119}
120
121static inline int getmiso(const struct spi_device *spi)
122{
123 return !!gpio_get_value_cansleep(SPI_MISO_GPIO);
124}
125
126#undef pdata
127
128/*
129 * NOTE: this clocks "as fast as we can". It "should" be a function of the
130 * requested device clock. Software overhead means we usually have trouble
131 * reaching even one Mbit/sec (except when we can inline bitops), so for now
132 * we'll just assume we never need additional per-bit slowdowns.
133 */
134#define spidelay(nsecs) do {} while (0)
135
136#include "spi-bitbang-txrx.h"
137
138/*
139 * These functions can leverage inline expansion of GPIO calls to shrink
140 * costs for a txrx bit, often by factors of around ten (by instruction
141 * count). That is particularly visible for larger word sizes, but helps
142 * even with default 8-bit words.
143 *
144 * REVISIT overheads calling these functions for each word also have
145 * significant performance costs. Having txrx_bufs() calls that inline
146 * the txrx_word() logic would help performance, e.g. on larger blocks
147 * used with flash storage or MMC/SD. There should also be ways to make
148 * GCC be less stupid about reloading registers inside the I/O loops,
149 * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
150 */
151
152static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
153 unsigned nsecs, u32 word, u8 bits)
154{
155 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
156}
157
158static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
159 unsigned nsecs, u32 word, u8 bits)
160{
161 return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
162}
163
164static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
165 unsigned nsecs, u32 word, u8 bits)
166{
167 return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
168}
169
170static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
171 unsigned nsecs, u32 word, u8 bits)
172{
173 return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
174}
175
176/*
177 * These functions do not call setmosi or getmiso if respective flag
178 * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
179 * call when such pin is not present or defined in the controller.
180 * A separate set of callbacks is defined to get highest possible
181 * speed in the generic case (when both MISO and MOSI lines are
182 * available), as optimiser will remove the checks when argument is
183 * constant.
184 */
185
186static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
187 unsigned nsecs, u32 word, u8 bits)
188{
189 unsigned flags = spi->master->flags;
190 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
191}
192
193static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
194 unsigned nsecs, u32 word, u8 bits)
195{
196 unsigned flags = spi->master->flags;
197 return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
198}
199
200static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
201 unsigned nsecs, u32 word, u8 bits)
202{
203 unsigned flags = spi->master->flags;
204 return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
205}
206
207static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
208 unsigned nsecs, u32 word, u8 bits)
209{
210 unsigned flags = spi->master->flags;
211 return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
212}
213
214/*----------------------------------------------------------------------*/
215
216static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
217{
218 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
219 unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
220
221 /* set initial clock polarity */
222 if (is_active)
223 setsck(spi, spi->mode & SPI_CPOL);
224
225 if (cs != SPI_GPIO_NO_CHIPSELECT) {
226 /* SPI is normally active-low */
227 gpio_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
228 }
229}
230
231static int spi_gpio_setup(struct spi_device *spi)
232{
233 unsigned long cs;
234 int status = 0;
235 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
236 struct device_node *np = spi->master->dev.of_node;
237
238 if (np) {
239 /*
240 * In DT environments, the CS GPIOs have already been
241 * initialized from the "cs-gpios" property of the node.
242 */
243 cs = spi_gpio->cs_gpios[spi->chip_select];
244 } else {
245 /*
246 * ... otherwise, take it from spi->controller_data
247 */
248 cs = (uintptr_t) spi->controller_data;
249 }
250
251 if (!spi->controller_state) {
252 if (cs != SPI_GPIO_NO_CHIPSELECT) {
253 status = gpio_request(cs, dev_name(&spi->dev));
254 if (status)
255 return status;
256 status = gpio_direction_output(cs,
257 !(spi->mode & SPI_CS_HIGH));
258 }
259 }
260 if (!status) {
261 /* in case it was initialized from static board data */
262 spi_gpio->cs_gpios[spi->chip_select] = cs;
263 status = spi_bitbang_setup(spi);
264 }
265
266 if (status) {
267 if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
268 gpio_free(cs);
269 }
270 return status;
271}
272
273static void spi_gpio_cleanup(struct spi_device *spi)
274{
275 struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
276 unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
277
278 if (cs != SPI_GPIO_NO_CHIPSELECT)
279 gpio_free(cs);
280 spi_bitbang_cleanup(spi);
281}
282
283static int spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
284{
285 int value;
286
287 value = gpio_request(pin, label);
288 if (value == 0) {
289 if (is_in)
290 value = gpio_direction_input(pin);
291 else
292 value = gpio_direction_output(pin, 0);
293 }
294 return value;
295}
296
297static int spi_gpio_request(struct spi_gpio_platform_data *pdata,
298 const char *label, u16 *res_flags)
299{
300 int value;
301
302 /* NOTE: SPI_*_GPIO symbols may reference "pdata" */
303
304 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
305 value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
306 if (value)
307 goto done;
308 } else {
309 /* HW configuration without MOSI pin */
310 *res_flags |= SPI_MASTER_NO_TX;
311 }
312
313 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
314 value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
315 if (value)
316 goto free_mosi;
317 } else {
318 /* HW configuration without MISO pin */
319 *res_flags |= SPI_MASTER_NO_RX;
320 }
321
322 value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
323 if (value)
324 goto free_miso;
325
326 goto done;
327
328free_miso:
329 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
330 gpio_free(SPI_MISO_GPIO);
331free_mosi:
332 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
333 gpio_free(SPI_MOSI_GPIO);
334done:
335 return value;
336}
337
338#ifdef CONFIG_OF
339static const struct of_device_id spi_gpio_dt_ids[] = {
340 { .compatible = "spi-gpio" },
341 {}
342};
343MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
344
345static int spi_gpio_probe_dt(struct platform_device *pdev)
346{
347 int ret;
348 u32 tmp;
349 struct spi_gpio_platform_data *pdata;
350 struct device_node *np = pdev->dev.of_node;
351 const struct of_device_id *of_id =
352 of_match_device(spi_gpio_dt_ids, &pdev->dev);
353
354 if (!of_id)
355 return 0;
356
357 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
358 if (!pdata)
359 return -ENOMEM;
360
361 ret = of_get_named_gpio(np, "gpio-sck", 0);
362 if (ret < 0) {
363 dev_err(&pdev->dev, "gpio-sck property not found\n");
364 goto error_free;
365 }
366 pdata->sck = ret;
367
368 ret = of_get_named_gpio(np, "gpio-miso", 0);
369 if (ret < 0) {
370 dev_info(&pdev->dev, "gpio-miso property not found, switching to no-rx mode\n");
371 pdata->miso = SPI_GPIO_NO_MISO;
372 } else
373 pdata->miso = ret;
374
375 ret = of_get_named_gpio(np, "gpio-mosi", 0);
376 if (ret < 0) {
377 dev_info(&pdev->dev, "gpio-mosi property not found, switching to no-tx mode\n");
378 pdata->mosi = SPI_GPIO_NO_MOSI;
379 } else
380 pdata->mosi = ret;
381
382 ret = of_property_read_u32(np, "num-chipselects", &tmp);
383 if (ret < 0) {
384 dev_err(&pdev->dev, "num-chipselects property not found\n");
385 goto error_free;
386 }
387
388 pdata->num_chipselect = tmp;
389 pdev->dev.platform_data = pdata;
390
391 return 1;
392
393error_free:
394 devm_kfree(&pdev->dev, pdata);
395 return ret;
396}
397#else
398static inline int spi_gpio_probe_dt(struct platform_device *pdev)
399{
400 return 0;
401}
402#endif
403
404static int spi_gpio_probe(struct platform_device *pdev)
405{
406 int status;
407 struct spi_master *master;
408 struct spi_gpio *spi_gpio;
409 struct spi_gpio_platform_data *pdata;
410 u16 master_flags = 0;
411 bool use_of = 0;
412 int num_devices;
413
414 status = spi_gpio_probe_dt(pdev);
415 if (status < 0)
416 return status;
417 if (status > 0)
418 use_of = 1;
419
420 pdata = dev_get_platdata(&pdev->dev);
421#ifdef GENERIC_BITBANG
422 if (!pdata || (!use_of && !pdata->num_chipselect))
423 return -ENODEV;
424#endif
425
426 if (use_of && !SPI_N_CHIPSEL)
427 num_devices = 1;
428 else
429 num_devices = SPI_N_CHIPSEL;
430
431 status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
432 if (status < 0)
433 return status;
434
435 master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio) +
436 (sizeof(unsigned long) * num_devices));
437 if (!master) {
438 status = -ENOMEM;
439 goto gpio_free;
440 }
441 spi_gpio = spi_master_get_devdata(master);
442 platform_set_drvdata(pdev, spi_gpio);
443
444 spi_gpio->pdev = pdev;
445 if (pdata)
446 spi_gpio->pdata = *pdata;
447
448 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
449 master->flags = master_flags;
450 master->bus_num = pdev->id;
451 master->num_chipselect = num_devices;
452 master->setup = spi_gpio_setup;
453 master->cleanup = spi_gpio_cleanup;
454#ifdef CONFIG_OF
455 master->dev.of_node = pdev->dev.of_node;
456
457 if (use_of) {
458 int i;
459 struct device_node *np = pdev->dev.of_node;
460
461 /*
462 * In DT environments, take the CS GPIO from the "cs-gpios"
463 * property of the node.
464 */
465
466 if (!SPI_N_CHIPSEL)
467 spi_gpio->cs_gpios[0] = SPI_GPIO_NO_CHIPSELECT;
468 else
469 for (i = 0; i < SPI_N_CHIPSEL; i++) {
470 status = of_get_named_gpio(np, "cs-gpios", i);
471 if (status < 0) {
472 dev_err(&pdev->dev,
473 "invalid cs-gpios property\n");
474 goto gpio_free;
475 }
476 spi_gpio->cs_gpios[i] = status;
477 }
478 }
479#endif
480
481 spi_gpio->bitbang.master = master;
482 spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
483
484 if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
485 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
486 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
487 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
488 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
489 } else {
490 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
491 spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
492 spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
493 spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
494 }
495 spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
496 spi_gpio->bitbang.flags = SPI_CS_HIGH;
497
498 status = spi_bitbang_start(&spi_gpio->bitbang);
499 if (status < 0) {
500gpio_free:
501 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
502 gpio_free(SPI_MISO_GPIO);
503 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
504 gpio_free(SPI_MOSI_GPIO);
505 gpio_free(SPI_SCK_GPIO);
506 spi_master_put(master);
507 }
508
509 return status;
510}
511
512static int spi_gpio_remove(struct platform_device *pdev)
513{
514 struct spi_gpio *spi_gpio;
515 struct spi_gpio_platform_data *pdata;
516
517 spi_gpio = platform_get_drvdata(pdev);
518 pdata = dev_get_platdata(&pdev->dev);
519
520 /* stop() unregisters child devices too */
521 spi_bitbang_stop(&spi_gpio->bitbang);
522
523 if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
524 gpio_free(SPI_MISO_GPIO);
525 if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
526 gpio_free(SPI_MOSI_GPIO);
527 gpio_free(SPI_SCK_GPIO);
528 spi_master_put(spi_gpio->bitbang.master);
529
530 return 0;
531}
532
533MODULE_ALIAS("platform:" DRIVER_NAME);
534
535static struct platform_driver spi_gpio_driver = {
536 .driver = {
537 .name = DRIVER_NAME,
538 .of_match_table = of_match_ptr(spi_gpio_dt_ids),
539 },
540 .probe = spi_gpio_probe,
541 .remove = spi_gpio_remove,
542};
543module_platform_driver(spi_gpio_driver);
544
545MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
546MODULE_AUTHOR("David Brownell");
547MODULE_LICENSE("GPL");