[deliverable/linux.git] / drivers / spi / 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/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/of_device.h>
#include <linux/of_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;
	int				cs_gpios[0];
};

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

/*
 * 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 struct spi_gpio * __pure
spi_to_spi_gpio(const struct spi_device *spi)
{
	const struct spi_bitbang	*bang;
	struct spi_gpio			*spi_gpio;

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

static inline struct spi_gpio_platform_data * __pure
spi_to_pdata(const struct spi_device *spi)
{
	return &spi_to_spi_gpio(spi)->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)

#include "spi-bitbang-txrx.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, 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, 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, 0, 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, 0, word, bits);
}

/*
 * These functions do not call setmosi or getmiso if respective flag
 * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
 * call when such pin is not present or defined in the controller.
 * A separate set of callbacks is defined to get highest possible
 * speed in the generic case (when both MISO and MOSI lines are
 * available), as optimiser will remove the checks when argument is
 * constant.
 */

static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	unsigned flags = spi->master->flags;
	return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
}

static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	unsigned flags = spi->master->flags;
	return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
}

static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	unsigned flags = spi->master->flags;
	return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
}

static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
		unsigned nsecs, u32 word, u8 bits)
{
	unsigned flags = spi->master->flags;
	return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
}

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

static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
{
	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
	unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];

	/* 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 int		cs;
	int			status = 0;
	struct spi_gpio		*spi_gpio = spi_to_spi_gpio(spi);
	struct device_node	*np = spi->master->dev.of_node;

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

	if (np) {
		/*
		 * In DT environments, the CS GPIOs have already been
		 * initialized from the "cs-gpios" property of the node.
		 */
		cs = spi_gpio->cs_gpios[spi->chip_select];
	} else {
		/*
		 * ... otherwise, take it from spi->controller_data
		 */
		cs = (unsigned int) spi->controller_data;
	}

	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);
		/* in case it was initialized from static board data */
		spi_gpio->cs_gpios[spi->chip_select] = cs;
	}

	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)
{
	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
	unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];

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

static int 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 spi_gpio_request(struct spi_gpio_platform_data *pdata,
			    const char *label, u16 *res_flags)
{
	int value;

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

	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
		value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
		if (value)
			goto done;
	} else {
		/* HW configuration without MOSI pin */
		*res_flags |= SPI_MASTER_NO_TX;
	}

	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
		value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
		if (value)
			goto free_mosi;
	} else {
		/* HW configuration without MISO pin */
		*res_flags |= SPI_MASTER_NO_RX;
	}

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

	goto done;

free_miso:
	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
		gpio_free(SPI_MISO_GPIO);
free_mosi:
	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
		gpio_free(SPI_MOSI_GPIO);
done:
	return value;
}

#ifdef CONFIG_OF
static struct of_device_id spi_gpio_dt_ids[] = {
	{ .compatible = "spi-gpio" },
	{}
};
MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);

static int spi_gpio_probe_dt(struct platform_device *pdev)
{
	int ret;
	u32 tmp;
	struct spi_gpio_platform_data	*pdata;
	struct device_node *np = pdev->dev.of_node;
	const struct of_device_id *of_id =
			of_match_device(spi_gpio_dt_ids, &pdev->dev);

	if (!of_id)
		return 0;

	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
		return -ENOMEM;

	pdata->sck = of_get_named_gpio(np, "gpio-sck", 0);
	pdata->miso = of_get_named_gpio(np, "gpio-miso", 0);
	pdata->mosi = of_get_named_gpio(np, "gpio-mosi", 0);

	ret = of_property_read_u32(np, "num-chipselects", &tmp);
	if (ret < 0) {
		dev_err(&pdev->dev, "num-chipselects property not found\n");
		goto error_free;
	}

	pdata->num_chipselect = tmp;
	pdev->dev.platform_data = pdata;

	return 1;

error_free:
	devm_kfree(&pdev->dev, pdata);
	return ret;
}
#else
static inline int spi_gpio_probe_dt(struct platform_device *pdev)
{
	return 0;
}
#endif

static int spi_gpio_probe(struct platform_device *pdev)
{
	int				status;
	struct spi_master		*master;
	struct spi_gpio			*spi_gpio;
	struct spi_gpio_platform_data	*pdata;
	u16 master_flags = 0;
	bool use_of = 0;

	status = spi_gpio_probe_dt(pdev);
	if (status < 0)
		return status;
	if (status > 0)
		use_of = 1;

	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), &master_flags);
	if (status < 0)
		return status;

	master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio) +
					(sizeof(int) * SPI_N_CHIPSEL));
	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->flags = master_flags;
	master->bus_num = pdev->id;
	master->num_chipselect = SPI_N_CHIPSEL;
	master->setup = spi_gpio_setup;
	master->cleanup = spi_gpio_cleanup;
#ifdef CONFIG_OF
	master->dev.of_node = pdev->dev.of_node;

	if (use_of) {
		int i;
		struct device_node *np = pdev->dev.of_node;

		/*
		 * In DT environments, take the CS GPIO from the "cs-gpios"
		 * property of the node.
		 */

		for (i = 0; i < SPI_N_CHIPSEL; i++)
			spi_gpio->cs_gpios[i] =
				of_get_named_gpio(np, "cs-gpios", i);
	}
#endif

	spi_gpio->bitbang.master = spi_master_get(master);
	spi_gpio->bitbang.chipselect = spi_gpio_chipselect;

	if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
		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;
	} else {
		spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
		spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
		spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
		spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_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:
		if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
			gpio_free(SPI_MISO_GPIO);
		if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
			gpio_free(SPI_MOSI_GPIO);
		gpio_free(SPI_SCK_GPIO);
		spi_master_put(master);
	}

	return status;
}

static int 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);

	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
		gpio_free(SPI_MISO_GPIO);
	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
		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,
		.owner	= THIS_MODULE,
		.of_match_table = of_match_ptr(spi_gpio_dt_ids),
	},
	.probe		= spi_gpio_probe,
	.remove		= spi_gpio_remove,
};
module_platform_driver(spi_gpio_driver);

MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
MODULE_AUTHOR("David Brownell");
MODULE_LICENSE("GPL");
Commit	Line	Data
d29389de	1	/*
ca632f55	2	* SPI master driver using generic bitbanged GPIO
d29389de DB	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>
d7614de4	21	#include <linux/module.h>
d29389de DB	22	#include <linux/init.h>
	23	#include <linux/platform_device.h>
	24	#include <linux/gpio.h>
38ab18ca DM	25	#include <linux/of_device.h>
38ab18ca DM	26	#include <linux/of_gpio.h>
d29389de DB	27
	28	#include <linux/spi/spi.h>
	29	#include <linux/spi/spi_bitbang.h>
	30	#include <linux/spi/spi_gpio.h>
	31
	32
	33	/*
	34	* This bitbanging SPI master driver should help make systems usable
	35	* when a native hardware SPI engine is not available, perhaps because
	36	* its driver isn't yet working or because the I/O pins it requires
	37	* are used for other purposes.
	38	*
	39	* platform_device->driver_data ... points to spi_gpio
	40	*
	41	* spi->controller_state ... reserved for bitbang framework code
	42	* spi->controller_data ... holds chipselect GPIO
	43	*
	44	* spi->master->dev.driver_data ... points to spi_gpio->bitbang
	45	*/
	46
	47	struct spi_gpio {
	48	struct spi_bitbang bitbang;
	49	struct spi_gpio_platform_data pdata;
	50	struct platform_device *pdev;
161c2dd3	51	int cs_gpios[0];
d29389de DB	52	};
	53
	54	/----------------------------------------------------------------------/
	55
	56	/*
	57	* Because the overhead of going through four GPIO procedure calls
	58	* per transferred bit can make performance a problem, this code
	59	* is set up so that you can use it in either of two ways:
	60	*
	61	* - The slow generic way: set up platform_data to hold the GPIO
	62	* numbers used for MISO/MOSI/SCK, and issue procedure calls for
	63	* each of them. This driver can handle several such busses.
	64	*
	65	* - The quicker inlined way: only helps with platform GPIO code
	66	* that inlines operations for constant GPIOs. This can give
	67	* you tight (fast!) inner loops, but each such bus needs a
	68	* new driver. You'll define a new C file, with Makefile and
	69	* Kconfig support; the C code can be a total of six lines:
	70	*
	71	* #define DRIVER_NAME "myboard_spi2"
	72	* #define SPI_MISO_GPIO 119
	73	* #define SPI_MOSI_GPIO 120
	74	* #define SPI_SCK_GPIO 121
	75	* #define SPI_N_CHIPSEL 4
ca632f55	76	* #include "spi-gpio.c"
d29389de DB	77	*/
	78
	79	#ifndef DRIVER_NAME
	80	#define DRIVER_NAME "spi_gpio"
	81
	82	#define GENERIC_BITBANG /* vs tight inlines */
	83
	84	/* all functions referencing these symbols must define pdata */
	85	#define SPI_MISO_GPIO ((pdata)->miso)
	86	#define SPI_MOSI_GPIO ((pdata)->mosi)
	87	#define SPI_SCK_GPIO ((pdata)->sck)
	88
	89	#define SPI_N_CHIPSEL ((pdata)->num_chipselect)
	90
	91	#endif
	92
	93	/----------------------------------------------------------------------/
	94
161c2dd3 DM	95	static inline struct spi_gpio * __pure
161c2dd3 DM	96	spi_to_spi_gpio(const struct spi_device *spi)
d29389de DB	97	{
d29389de DB	98	const struct spi_bitbang *bang;
161c2dd3	99	struct spi_gpio *spi_gpio;
d29389de DB	100
	101	bang = spi_master_get_devdata(spi->master);
	102	spi_gpio = container_of(bang, struct spi_gpio, bitbang);
161c2dd3 DM	103	return spi_gpio;
	104	}
	105
	106	static inline struct spi_gpio_platform_data * __pure
	107	spi_to_pdata(const struct spi_device *spi)
	108	{
	109	return &spi_to_spi_gpio(spi)->pdata;
d29389de DB	110	}
	111
	112	/* this is #defined to avoid unused-variable warnings when inlining */
	113	#define pdata spi_to_pdata(spi)
	114
	115	static inline void setsck(const struct spi_device *spi, int is_on)
	116	{
	117	gpio_set_value(SPI_SCK_GPIO, is_on);
	118	}
	119
	120	static inline void setmosi(const struct spi_device *spi, int is_on)
	121	{
	122	gpio_set_value(SPI_MOSI_GPIO, is_on);
	123	}
	124
	125	static inline int getmiso(const struct spi_device *spi)
	126	{
be50344e	127	return !!gpio_get_value(SPI_MISO_GPIO);
d29389de DB	128	}
	129
	130	#undef pdata
	131
	132	/*
	133	* NOTE: this clocks "as fast as we can". It "should" be a function of the
	134	* requested device clock. Software overhead means we usually have trouble
	135	* reaching even one Mbit/sec (except when we can inline bitops), so for now
	136	* we'll just assume we never need additional per-bit slowdowns.
	137	*/
	138	#define spidelay(nsecs) do {} while (0)
	139
ca632f55	140	#include "spi-bitbang-txrx.h"
d29389de DB	141
	142	/*
	143	* These functions can leverage inline expansion of GPIO calls to shrink
	144	* costs for a txrx bit, often by factors of around ten (by instruction
	145	* count). That is particularly visible for larger word sizes, but helps
	146	* even with default 8-bit words.
	147	*
	148	* REVISIT overheads calling these functions for each word also have
	149	* significant performance costs. Having txrx_bufs() calls that inline
	150	* the txrx_word() logic would help performance, e.g. on larger blocks
	151	* used with flash storage or MMC/SD. There should also be ways to make
	152	* GCC be less stupid about reloading registers inside the I/O loops,
	153	* even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
	154	*/
	155
	156	static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
	157	unsigned nsecs, u32 word, u8 bits)
	158	{
04bb2a03	159	return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
d29389de DB	160	}
	161
	162	static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
	163	unsigned nsecs, u32 word, u8 bits)
	164	{
04bb2a03	165	return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
d29389de DB	166	}
	167
	168	static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
	169	unsigned nsecs, u32 word, u8 bits)
	170	{
04bb2a03	171	return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
d29389de DB	172	}
	173
	174	static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
	175	unsigned nsecs, u32 word, u8 bits)
	176	{
04bb2a03	177	return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
d29389de DB	178	}
d29389de DB	179
3c8e1a84 MS	180	/*
	181	* These functions do not call setmosi or getmiso if respective flag
	182	* (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
	183	* call when such pin is not present or defined in the controller.
	184	* A separate set of callbacks is defined to get highest possible
	185	* speed in the generic case (when both MISO and MOSI lines are
	186	* available), as optimiser will remove the checks when argument is
	187	* constant.
	188	*/
	189
	190	static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
	191	unsigned nsecs, u32 word, u8 bits)
	192	{
	193	unsigned flags = spi->master->flags;
	194	return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
	195	}
	196
	197	static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
	198	unsigned nsecs, u32 word, u8 bits)
	199	{
	200	unsigned flags = spi->master->flags;
	201	return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
	202	}
	203
	204	static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
	205	unsigned nsecs, u32 word, u8 bits)
	206	{
	207	unsigned flags = spi->master->flags;
	208	return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
	209	}
	210
	211	static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
	212	unsigned nsecs, u32 word, u8 bits)
	213	{
	214	unsigned flags = spi->master->flags;
	215	return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
	216	}
	217
d29389de DB	218	/----------------------------------------------------------------------/
	219
	220	static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
	221	{
161c2dd3 DM	222	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
161c2dd3 DM	223	unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];
d29389de DB	224
	225	/* set initial clock polarity */
	226	if (is_active)
	227	setsck(spi, spi->mode & SPI_CPOL);
	228
bfb9bcdb MB	229	if (cs != SPI_GPIO_NO_CHIPSELECT) {
	230	/* SPI is normally active-low */
	231	gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
	232	}
d29389de DB	233	}
	234
	235	static int spi_gpio_setup(struct spi_device *spi)
	236	{
38ab18ca	237	unsigned int cs;
161c2dd3 DM	238	int status = 0;
161c2dd3 DM	239	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
38ab18ca	240	struct device_node *np = spi->master->dev.of_node;
d29389de DB	241
	242	if (spi->bits_per_word > 32)
	243	return -EINVAL;
	244
38ab18ca DM	245	if (np) {
	246	/*
	247	* In DT environments, the CS GPIOs have already been
	248	* initialized from the "cs-gpios" property of the node.
	249	*/
	250	cs = spi_gpio->cs_gpios[spi->chip_select];
	251	} else {
	252	/*
	253	* ... otherwise, take it from spi->controller_data
	254	*/
	255	cs = (unsigned int) spi->controller_data;
	256	}
	257
d29389de	258	if (!spi->controller_state) {
bfb9bcdb MB	259	if (cs != SPI_GPIO_NO_CHIPSELECT) {
	260	status = gpio_request(cs, dev_name(&spi->dev));
	261	if (status)
	262	return status;
05644147 UKK	263	status = gpio_direction_output(cs,
05644147 UKK	264	!(spi->mode & SPI_CS_HIGH));
bfb9bcdb	265	}
d29389de	266	}
161c2dd3	267	if (!status) {
d29389de	268	status = spi_bitbang_setup(spi);
38ab18ca	269	/* in case it was initialized from static board data */
161c2dd3 DM	270	spi_gpio->cs_gpios[spi->chip_select] = cs;
	271	}
	272
d29389de	273	if (status) {
bfb9bcdb	274	if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
d29389de DB	275	gpio_free(cs);
	276	}
	277	return status;
	278	}
	279
	280	static void spi_gpio_cleanup(struct spi_device *spi)
	281	{
161c2dd3 DM	282	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
161c2dd3 DM	283	unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];
d29389de	284
bfb9bcdb MB	285	if (cs != SPI_GPIO_NO_CHIPSELECT)
bfb9bcdb MB	286	gpio_free(cs);
d29389de DB	287	spi_bitbang_cleanup(spi);
	288	}
	289
fd4a319b	290	static int spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
d29389de DB	291	{
	292	int value;
	293
	294	value = gpio_request(pin, label);
	295	if (value == 0) {
	296	if (is_in)
	297	value = gpio_direction_input(pin);
	298	else
	299	value = gpio_direction_output(pin, 0);
	300	}
	301	return value;
	302	}
	303
fd4a319b GL	304	static int spi_gpio_request(struct spi_gpio_platform_data *pdata,
fd4a319b GL	305	const char label, u16 res_flags)
d29389de DB	306	{
	307	int value;
	308
	309	/* NOTE: SPI__GPIO symbols may reference "pdata" /
	310
3c8e1a84 MS	311	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
	312	value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
	313	if (value)
	314	goto done;
	315	} else {
	316	/* HW configuration without MOSI pin */
	317	*res_flags \|= SPI_MASTER_NO_TX;
	318	}
d29389de	319
3c8e1a84 MS	320	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
	321	value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
	322	if (value)
	323	goto free_mosi;
	324	} else {
	325	/* HW configuration without MISO pin */
	326	*res_flags \|= SPI_MASTER_NO_RX;
	327	}
d29389de DB	328
	329	value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
	330	if (value)
	331	goto free_miso;
	332
	333	goto done;
	334
	335	free_miso:
3c8e1a84 MS	336	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
3c8e1a84 MS	337	gpio_free(SPI_MISO_GPIO);
d29389de	338	free_mosi:
3c8e1a84 MS	339	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
3c8e1a84 MS	340	gpio_free(SPI_MOSI_GPIO);
d29389de DB	341	done:
	342	return value;
	343	}
	344
38ab18ca DM	345	#ifdef CONFIG_OF
	346	static struct of_device_id spi_gpio_dt_ids[] = {
	347	{ .compatible = "spi-gpio" },
	348	{}
	349	};
	350	MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
	351
	352	static int spi_gpio_probe_dt(struct platform_device *pdev)
	353	{
	354	int ret;
	355	u32 tmp;
	356	struct spi_gpio_platform_data *pdata;
	357	struct device_node *np = pdev->dev.of_node;
	358	const struct of_device_id *of_id =
	359	of_match_device(spi_gpio_dt_ids, &pdev->dev);
	360
	361	if (!of_id)
	362	return 0;
	363
	364	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
	365	if (!pdata)
	366	return -ENOMEM;
	367
	368	pdata->sck = of_get_named_gpio(np, "gpio-sck", 0);
	369	pdata->miso = of_get_named_gpio(np, "gpio-miso", 0);
	370	pdata->mosi = of_get_named_gpio(np, "gpio-mosi", 0);
	371
	372	ret = of_property_read_u32(np, "num-chipselects", &tmp);
	373	if (ret < 0) {
	374	dev_err(&pdev->dev, "num-chipselects property not found\n");
	375	goto error_free;
	376	}
	377
	378	pdata->num_chipselect = tmp;
	379	pdev->dev.platform_data = pdata;
	380
	381	return 1;
	382
	383	error_free:
	384	devm_kfree(&pdev->dev, pdata);
	385	return ret;
	386	}
	387	#else
ac2cb30b	388	static inline int spi_gpio_probe_dt(struct platform_device *pdev)
38ab18ca DM	389	{
	390	return 0;
	391	}
	392	#endif
	393
fd4a319b	394	static int spi_gpio_probe(struct platform_device *pdev)
d29389de DB	395	{
	396	int status;
	397	struct spi_master *master;
	398	struct spi_gpio *spi_gpio;
	399	struct spi_gpio_platform_data *pdata;
3c8e1a84	400	u16 master_flags = 0;
38ab18ca DM	401	bool use_of = 0;
	402
	403	status = spi_gpio_probe_dt(pdev);
	404	if (status < 0)
	405	return status;
	406	if (status > 0)
	407	use_of = 1;
d29389de DB	408
	409	pdata = pdev->dev.platform_data;
	410	#ifdef GENERIC_BITBANG
	411	if (!pdata \|\| !pdata->num_chipselect)
	412	return -ENODEV;
	413	#endif
	414
3c8e1a84	415	status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
d29389de DB	416	if (status < 0)
	417	return status;
	418
161c2dd3 DM	419	master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio) +
161c2dd3 DM	420	(sizeof(int) * SPI_N_CHIPSEL));
d29389de DB	421	if (!master) {
	422	status = -ENOMEM;
	423	goto gpio_free;
	424	}
	425	spi_gpio = spi_master_get_devdata(master);
	426	platform_set_drvdata(pdev, spi_gpio);
	427
	428	spi_gpio->pdev = pdev;
	429	if (pdata)
	430	spi_gpio->pdata = *pdata;
	431
3c8e1a84	432	master->flags = master_flags;
d29389de DB	433	master->bus_num = pdev->id;
	434	master->num_chipselect = SPI_N_CHIPSEL;
	435	master->setup = spi_gpio_setup;
	436	master->cleanup = spi_gpio_cleanup;
38ab18ca DM	437	#ifdef CONFIG_OF
	438	master->dev.of_node = pdev->dev.of_node;
	439
	440	if (use_of) {
	441	int i;
	442	struct device_node *np = pdev->dev.of_node;
	443
	444	/*
	445	* In DT environments, take the CS GPIO from the "cs-gpios"
	446	* property of the node.
	447	*/
	448
	449	for (i = 0; i < SPI_N_CHIPSEL; i++)
	450	spi_gpio->cs_gpios[i] =
	451	of_get_named_gpio(np, "cs-gpios", i);
	452	}
	453	#endif
d29389de DB	454
	455	spi_gpio->bitbang.master = spi_master_get(master);
	456	spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
3c8e1a84	457
23699f98	458	if ((master_flags & (SPI_MASTER_NO_TX \| SPI_MASTER_NO_RX)) == 0) {
3c8e1a84 MS	459	spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
	460	spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
	461	spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
	462	spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
	463	} else {
	464	spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
	465	spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
	466	spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
	467	spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
	468	}
d29389de DB	469	spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
	470	spi_gpio->bitbang.flags = SPI_CS_HIGH;
	471
	472	status = spi_bitbang_start(&spi_gpio->bitbang);
	473	if (status < 0) {
	474	spi_master_put(spi_gpio->bitbang.master);
	475	gpio_free:
3c8e1a84 MS	476	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
	477	gpio_free(SPI_MISO_GPIO);
	478	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
	479	gpio_free(SPI_MOSI_GPIO);
d29389de DB	480	gpio_free(SPI_SCK_GPIO);
	481	spi_master_put(master);
	482	}
	483
	484	return status;
	485	}
	486
fd4a319b	487	static int spi_gpio_remove(struct platform_device *pdev)
d29389de DB	488	{
	489	struct spi_gpio *spi_gpio;
	490	struct spi_gpio_platform_data *pdata;
	491	int status;
	492
	493	spi_gpio = platform_get_drvdata(pdev);
	494	pdata = pdev->dev.platform_data;
	495
	496	/* stop() unregisters child devices too */
	497	status = spi_bitbang_stop(&spi_gpio->bitbang);
	498	spi_master_put(spi_gpio->bitbang.master);
	499
	500	platform_set_drvdata(pdev, NULL);
	501
3c8e1a84 MS	502	if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
	503	gpio_free(SPI_MISO_GPIO);
	504	if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
	505	gpio_free(SPI_MOSI_GPIO);
d29389de DB	506	gpio_free(SPI_SCK_GPIO);
	507
	508	return status;
	509	}
	510
	511	MODULE_ALIAS("platform:" DRIVER_NAME);
	512
	513	static struct platform_driver spi_gpio_driver = {
38ab18ca DM	514	.driver = {
	515	.name = DRIVER_NAME,
	516	.owner = THIS_MODULE,
	517	.of_match_table = of_match_ptr(spi_gpio_dt_ids),
	518	},
940ab889	519	.probe = spi_gpio_probe,
fd4a319b	520	.remove = spi_gpio_remove,
d29389de	521	};
940ab889	522	module_platform_driver(spi_gpio_driver);
d29389de DB	523
	524	MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
	525	MODULE_AUTHOR("David Brownell");
	526	MODULE_LICENSE("GPL");