[linux-2.6-block.git] / drivers / spi / spi_gpio.c

/*
 * spi_gpio.c - SPI master driver using generic bitbanged GPIO
 *
 * Copyright (C) 2006,2008 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>

#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/spi/spi_gpio.h>


/*
 * This bitbanging SPI master driver should help make systems usable
 * when a native hardware SPI engine is not available, perhaps because
 * its driver isn't yet working or because the I/O pins it requires
 * are used for other purposes.
 *
 * platform_device->driver_data ... points to spi_gpio
 *
 * spi->controller_state ... reserved for bitbang framework code
 * spi->controller_data ... holds chipselect GPIO
 *
 * spi->master->dev.driver_data ... points to spi_gpio->bitbang
 */

struct spi_gpio {
	struct spi_bitbang		bitbang;
	struct spi_gpio_platform_data	pdata;
	struct platform_device		*pdev;
};

/*----------------------------------------------------------------------*/

/*
 * Because the overhead of going through four GPIO procedure calls
 * per transferred bit can make performance a problem, this code
 * is set up so that you can use it in either of two ways:
 *
 *   - The slow generic way:  set up platform_data to hold the GPIO
 *     numbers used for MISO/MOSI/SCK, and issue procedure calls for
 *     each of them.  This driver can handle several such busses.
 *
 *   - The quicker inlined way:  only helps with platform GPIO code
 *     that inlines operations for constant GPIOs.  This can give
 *     you tight (fast!) inner loops, but each such bus needs a
 *     new driver.  You'll define a new C file, with Makefile and
 *     Kconfig support; the C code can be a total of six lines:
 *
 *		#define DRIVER_NAME	"myboard_spi2"
 *		#define	SPI_MISO_GPIO	119
 *		#define	SPI_MOSI_GPIO	120
 *		#define	SPI_SCK_GPIO	121
 *		#define	SPI_N_CHIPSEL	4
 *		#include "spi_gpio.c"
 */

#ifndef DRIVER_NAME
#define DRIVER_NAME	"spi_gpio"

#define GENERIC_BITBANG	/* vs tight inlines */

/* all functions referencing these symbols must define pdata */
#define SPI_MISO_GPIO	((pdata)->miso)
#define SPI_MOSI_GPIO	((pdata)->mosi)
#define SPI_SCK_GPIO	((pdata)->sck)

#define SPI_N_CHIPSEL	((pdata)->num_chipselect)

#endif

/*----------------------------------------------------------------------*/

static inline const struct spi_gpio_platform_data * __pure
spi_to_pdata(const struct spi_device *spi)
{
	const struct spi_bitbang	*bang;
	const struct spi_gpio		*spi_gpio;

	bang = spi_master_get_devdata(spi->master);
	spi_gpio = container_of(bang, struct spi_gpio, bitbang);
	return &spi_gpio->pdata;
}

/* this is #defined to avoid unused-variable warnings when inlining */
#define pdata		spi_to_pdata(spi)

static inline void setsck(const struct spi_device *spi, int is_on)
{
	gpio_set_value(SPI_SCK_GPIO, is_on);
}

static inline void setmosi(const struct spi_device *spi, int is_on)
{
	gpio_set_value(SPI_MOSI_GPIO, is_on);
}

static inline int getmiso(const struct spi_device *spi)
{
	return !!gpio_get_value(SPI_MISO_GPIO);
}

#undef pdata

/*
 * NOTE:  this clocks "as fast as we can".  It "should" be a function of the
 * requested device clock.  Software overhead means we usually have trouble
 * reaching even one Mbit/sec (except when we can inline bitops), so for now
 * we'll just assume we never need additional per-bit slowdowns.
 */
#define spidelay(nsecs)	do {} while (0)

#define	EXPAND_BITBANG_TXRX
#include <linux/spi/spi_bitbang.h>

/*
 * These functions can leverage inline expansion of GPIO calls to shrink
 * costs for a txrx bit, often by factors of around ten (by instruction
 * count).  That is particularly visible for larger word sizes, but helps
 * even with default 8-bit words.
 *
 * REVISIT overheads calling these functions for each word also have
 * significant performance costs.  Having txrx_bufs() calls that inline
 * the txrx_word() logic would help performance, e.g. on larger blocks
 * used with flash storage or MMC/SD.  There should also be ways to make
 * GCC be less stupid about reloading registers inside the I/O loops,
 * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
 */

static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
}

static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	return bitbang_txrx_be_cpha1(spi, nsecs, 0, word, bits);
}

static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	return bitbang_txrx_be_cpha0(spi, nsecs, 1, word, bits);
}

static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	return bitbang_txrx_be_cpha1(spi, nsecs, 1, word, bits);
}

/*----------------------------------------------------------------------*/

static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
{
	unsigned long cs = (unsigned long) spi->controller_data;

	/* set initial clock polarity */
	if (is_active)
		setsck(spi, spi->mode & SPI_CPOL);

	if (cs != SPI_GPIO_NO_CHIPSELECT) {
		/* SPI is normally active-low */
		gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
	}
}

static int spi_gpio_setup(struct spi_device *spi)
{
	unsigned long	cs = (unsigned long) spi->controller_data;
	int		status = 0;

	if (spi->bits_per_word > 32)
		return -EINVAL;

	if (!spi->controller_state) {
		if (cs != SPI_GPIO_NO_CHIPSELECT) {
			status = gpio_request(cs, dev_name(&spi->dev));
			if (status)
				return status;
			status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
		}
	}
	if (!status)
		status = spi_bitbang_setup(spi);
	if (status) {
		if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
			gpio_free(cs);
	}
	return status;
}

static void spi_gpio_cleanup(struct spi_device *spi)
{
	unsigned long	cs = (unsigned long) spi->controller_data;

	if (cs != SPI_GPIO_NO_CHIPSELECT)
		gpio_free(cs);
	spi_bitbang_cleanup(spi);
}

static int __init spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
{
	int value;

	value = gpio_request(pin, label);
	if (value == 0) {
		if (is_in)
			value = gpio_direction_input(pin);
		else
			value = gpio_direction_output(pin, 0);
	}
	return value;
}

static int __init
spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label)
{
	int value;

	/* NOTE:  SPI_*_GPIO symbols may reference "pdata" */

	value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
	if (value)
		goto done;

	value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
	if (value)
		goto free_mosi;

	value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
	if (value)
		goto free_miso;

	goto done;

free_miso:
	gpio_free(SPI_MISO_GPIO);
free_mosi:
	gpio_free(SPI_MOSI_GPIO);
done:
	return value;
}

static int __init spi_gpio_probe(struct platform_device *pdev)
{
	int				status;
	struct spi_master		*master;
	struct spi_gpio			*spi_gpio;
	struct spi_gpio_platform_data	*pdata;

	pdata = pdev->dev.platform_data;
#ifdef GENERIC_BITBANG
	if (!pdata || !pdata->num_chipselect)
		return -ENODEV;
#endif

	status = spi_gpio_request(pdata, dev_name(&pdev->dev));
	if (status < 0)
		return status;

	master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio);
	if (!master) {
		status = -ENOMEM;
		goto gpio_free;
	}
	spi_gpio = spi_master_get_devdata(master);
	platform_set_drvdata(pdev, spi_gpio);

	spi_gpio->pdev = pdev;
	if (pdata)
		spi_gpio->pdata = *pdata;

	master->bus_num = pdev->id;
	master->num_chipselect = SPI_N_CHIPSEL;
	master->setup = spi_gpio_setup;
	master->cleanup = spi_gpio_cleanup;

	spi_gpio->bitbang.master = spi_master_get(master);
	spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
	spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
	spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
	spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
	spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
	spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
	spi_gpio->bitbang.flags = SPI_CS_HIGH;

	status = spi_bitbang_start(&spi_gpio->bitbang);
	if (status < 0) {
		spi_master_put(spi_gpio->bitbang.master);
gpio_free:
		gpio_free(SPI_MISO_GPIO);
		gpio_free(SPI_MOSI_GPIO);
		gpio_free(SPI_SCK_GPIO);
		spi_master_put(master);
	}

	return status;
}

static int __exit spi_gpio_remove(struct platform_device *pdev)
{
	struct spi_gpio			*spi_gpio;
	struct spi_gpio_platform_data	*pdata;
	int				status;

	spi_gpio = platform_get_drvdata(pdev);
	pdata = pdev->dev.platform_data;

	/* stop() unregisters child devices too */
	status = spi_bitbang_stop(&spi_gpio->bitbang);
	spi_master_put(spi_gpio->bitbang.master);

	platform_set_drvdata(pdev, NULL);

	gpio_free(SPI_MISO_GPIO);
	gpio_free(SPI_MOSI_GPIO);
	gpio_free(SPI_SCK_GPIO);

	return status;
}

MODULE_ALIAS("platform:" DRIVER_NAME);

static struct platform_driver spi_gpio_driver = {
	.driver.name	= DRIVER_NAME,
	.driver.owner	= THIS_MODULE,
	.remove		= __exit_p(spi_gpio_remove),
};

static int __init spi_gpio_init(void)
{
	return platform_driver_probe(&spi_gpio_driver, spi_gpio_probe);
}
module_init(spi_gpio_init);

static void __exit spi_gpio_exit(void)
{
	platform_driver_unregister(&spi_gpio_driver);
}
module_exit(spi_gpio_exit);


MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
MODULE_AUTHOR("David Brownell");
MODULE_LICENSE("GPL");
Commit	Line	Data
d29389de DB	1	/*
	2	* spi_gpio.c - 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
	44	struct 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
91	static inline const struct spi_gpio_platform_data * __pure
92	spi_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
105	static inline void setsck(const struct spi_device *spi, int is_on)
106	{
107	gpio_set_value(SPI_SCK_GPIO, is_on);
108	}
109
110	static inline void setmosi(const struct spi_device *spi, int is_on)
111	{
112	gpio_set_value(SPI_MOSI_GPIO, is_on);
113	}
114
115	static inline int getmiso(const struct spi_device *spi)
116	{
be50344e	117	return !!gpio_get_value(SPI_MISO_GPIO);
d29389de DB	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	#define EXPAND_BITBANG_TXRX
	131	#include <linux/spi/spi_bitbang.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
	147	static 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, word, bits);
	151	}
	152
	153	static 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, word, bits);
	157	}
	158
	159	static 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, word, bits);
	163	}
	164
	165	static 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, word, bits);
	169	}
	170
	171	/----------------------------------------------------------------------/
	172
	173	static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
	174	{
	175	unsigned long cs = (unsigned long) spi->controller_data;
	176
	177	/* set initial clock polarity */
	178	if (is_active)
	179	setsck(spi, spi->mode & SPI_CPOL);
	180
bfb9bcdb MB	181	if (cs != SPI_GPIO_NO_CHIPSELECT) {
	182	/* SPI is normally active-low */
	183	gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
	184	}
d29389de DB	185	}
	186
	187	static int spi_gpio_setup(struct spi_device *spi)
	188	{
	189	unsigned long cs = (unsigned long) spi->controller_data;
	190	int status = 0;
	191
	192	if (spi->bits_per_word > 32)
	193	return -EINVAL;
	194
	195	if (!spi->controller_state) {
bfb9bcdb MB	196	if (cs != SPI_GPIO_NO_CHIPSELECT) {
	197	status = gpio_request(cs, dev_name(&spi->dev));
	198	if (status)
	199	return status;
	200	status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
	201	}
d29389de DB	202	}
	203	if (!status)
	204	status = spi_bitbang_setup(spi);
	205	if (status) {
bfb9bcdb	206	if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
d29389de DB	207	gpio_free(cs);
	208	}
	209	return status;
	210	}
	211
	212	static void spi_gpio_cleanup(struct spi_device *spi)
	213	{
	214	unsigned long cs = (unsigned long) spi->controller_data;
	215
bfb9bcdb MB	216	if (cs != SPI_GPIO_NO_CHIPSELECT)
bfb9bcdb MB	217	gpio_free(cs);
d29389de DB	218	spi_bitbang_cleanup(spi);
	219	}
	220
	221	static int __init spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
	222	{
	223	int value;
	224
	225	value = gpio_request(pin, label);
	226	if (value == 0) {
	227	if (is_in)
	228	value = gpio_direction_input(pin);
	229	else
	230	value = gpio_direction_output(pin, 0);
	231	}
	232	return value;
	233	}
	234
	235	static int __init
	236	spi_gpio_request(struct spi_gpio_platform_data pdata, const char label)
	237	{
	238	int value;
	239
	240	/* NOTE: SPI__GPIO symbols may reference "pdata" /
	241
	242	value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
	243	if (value)
	244	goto done;
	245
	246	value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
	247	if (value)
	248	goto free_mosi;
	249
	250	value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
	251	if (value)
	252	goto free_miso;
	253
	254	goto done;
	255
	256	free_miso:
	257	gpio_free(SPI_MISO_GPIO);
	258	free_mosi:
	259	gpio_free(SPI_MOSI_GPIO);
	260	done:
	261	return value;
	262	}
	263
	264	static int __init spi_gpio_probe(struct platform_device *pdev)
	265	{
	266	int status;
	267	struct spi_master *master;
	268	struct spi_gpio *spi_gpio;
	269	struct spi_gpio_platform_data *pdata;
	270
	271	pdata = pdev->dev.platform_data;
	272	#ifdef GENERIC_BITBANG
	273	if (!pdata \|\| !pdata->num_chipselect)
	274	return -ENODEV;
	275	#endif
	276
	277	status = spi_gpio_request(pdata, dev_name(&pdev->dev));
	278	if (status < 0)
	279	return status;
	280
	281	master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio);
282	if (!master) {
283	status = -ENOMEM;
284	goto gpio_free;
285	}
286	spi_gpio = spi_master_get_devdata(master);
287	platform_set_drvdata(pdev, spi_gpio);
288
289	spi_gpio->pdev = pdev;
290	if (pdata)
291	spi_gpio->pdata = *pdata;
292
293	master->bus_num = pdev->id;
294	master->num_chipselect = SPI_N_CHIPSEL;
295	master->setup = spi_gpio_setup;
296	master->cleanup = spi_gpio_cleanup;
297
298	spi_gpio->bitbang.master = spi_master_get(master);
299	spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
300	spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
301	spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
302	spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
303	spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
304	spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
305	spi_gpio->bitbang.flags = SPI_CS_HIGH;
306
307	status = spi_bitbang_start(&spi_gpio->bitbang);
308	if (status < 0) {
309	spi_master_put(spi_gpio->bitbang.master);
310	gpio_free:
311	gpio_free(SPI_MISO_GPIO);
312	gpio_free(SPI_MOSI_GPIO);
313	gpio_free(SPI_SCK_GPIO);
314	spi_master_put(master);
315	}
316
317	return status;
318	}
319
320	static int __exit spi_gpio_remove(struct platform_device *pdev)
321	{
322	struct spi_gpio *spi_gpio;
323	struct spi_gpio_platform_data *pdata;
324	int status;
325
326	spi_gpio = platform_get_drvdata(pdev);
327	pdata = pdev->dev.platform_data;
328
329	/* stop() unregisters child devices too */
330	status = spi_bitbang_stop(&spi_gpio->bitbang);
331	spi_master_put(spi_gpio->bitbang.master);
332
333	platform_set_drvdata(pdev, NULL);
334
335	gpio_free(SPI_MISO_GPIO);
336	gpio_free(SPI_MOSI_GPIO);
337	gpio_free(SPI_SCK_GPIO);
338
339	return status;
340	}
341
342	MODULE_ALIAS("platform:" DRIVER_NAME);
343
344	static struct platform_driver spi_gpio_driver = {
345	.driver.name = DRIVER_NAME,
346	.driver.owner = THIS_MODULE,
347	.remove = __exit_p(spi_gpio_remove),
348	};
349
350	static int __init spi_gpio_init(void)
351	{
352	return platform_driver_probe(&spi_gpio_driver, spi_gpio_probe);
353	}
354	module_init(spi_gpio_init);
355
356	static void __exit spi_gpio_exit(void)
357	{
358	platform_driver_unregister(&spi_gpio_driver);
359	}
360	module_exit(spi_gpio_exit);
361
362
363	MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
364	MODULE_AUTHOR("David Brownell");
365	MODULE_LICENSE("GPL");