drivers/gpio/mcp23s08.c - pub/scm/linux/kernel/git/linusw/linux-gpio - Git at Google

 /*
  * mcp23s08.c - SPI gpio expander driver
  */

 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/workqueue.h>
 #include <linux/mutex.h>

 #include <linux/spi/spi.h>
 #include <linux/spi/mcp23s08.h>

 #include <asm/gpio.h>


 /* Registers are all 8 bits wide.
  *
  * The mcp23s17 has twice as many bits, and can be configured to work
  * with either 16 bit registers or with two adjacent 8 bit banks.
  *
  * Also, there are I2C versions of both chips.
  */
 #define MCP_IODIR	0x00		/* init/reset:  all ones */
 #define MCP_IPOL	0x01
 #define MCP_GPINTEN	0x02
 #define MCP_DEFVAL	0x03
 #define MCP_INTCON	0x04
 #define MCP_IOCON	0x05
 #	define IOCON_SEQOP	(1 << 5)
 #	define IOCON_HAEN	(1 << 3)
 #	define IOCON_ODR	(1 << 2)
 #	define IOCON_INTPOL	(1 << 1)
 #define MCP_GPPU	0x06
 #define MCP_INTF	0x07
 #define MCP_INTCAP	0x08
 #define MCP_GPIO	0x09
 #define MCP_OLAT	0x0a

 struct mcp23s08 {
 	struct spi_device	*spi;
 	u8			addr;

 	u8			cache[11];
 	/* lock protects the cached values */
 	struct mutex		lock;

 	struct gpio_chip	chip;

 	struct work_struct	work;
 };

 /* A given spi_device can represent up to four mcp23s08 chips
  * sharing the same chipselect but using different addresses
  * (e.g. chips #0 and #3 might be populated, but not #1 or $2).
  * Driver data holds all the per-chip data.
  */
 struct mcp23s08_driver_data {
 	unsigned		ngpio;
 	struct mcp23s08		*mcp[4];
 	struct mcp23s08		chip[];
 };

 static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
 {
 	u8	tx[2], rx[1];
 	int	status;

 	tx[0] = mcp->addr | 0x01;
 	tx[1] = reg;
 	status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
 	return (status < 0) ? status : rx[0];
 }

 static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
 {
 	u8	tx[3];

 	tx[0] = mcp->addr;
 	tx[1] = reg;
 	tx[2] = val;
 	return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
 }

 static int
 mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
 {
 	u8	tx[2];

 	if ((n + reg) > sizeof mcp->cache)
 		return -EINVAL;
 	tx[0] = mcp->addr | 0x01;
 	tx[1] = reg;
 	return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
 }

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

 static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
 {
 	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
 	int status;

 	mutex_lock(&mcp->lock);
 	mcp->cache[MCP_IODIR] |= (1 << offset);
 	status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
 	mutex_unlock(&mcp->lock);
 	return status;
 }

 static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
 {
 	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
 	int status;

 	mutex_lock(&mcp->lock);

 	/* REVISIT reading this clears any IRQ ... */
 	status = mcp23s08_read(mcp, MCP_GPIO);
 	if (status < 0)
 		status = 0;
 	else {
 		mcp->cache[MCP_GPIO] = status;
 		status = !!(status & (1 << offset));
 	}
 	mutex_unlock(&mcp->lock);
 	return status;
 }

 static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
 {
 	u8 olat = mcp->cache[MCP_OLAT];

 	if (value)
 		olat |= mask;
 	else
 		olat &= ~mask;
 	mcp->cache[MCP_OLAT] = olat;
 	return mcp23s08_write(mcp, MCP_OLAT, olat);
 }

 static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
 	u8 mask = 1 << offset;

 	mutex_lock(&mcp->lock);
 	__mcp23s08_set(mcp, mask, value);
 	mutex_unlock(&mcp->lock);
 }

 static int
 mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
 	u8 mask = 1 << offset;
 	int status;

 	mutex_lock(&mcp->lock);
 	status = __mcp23s08_set(mcp, mask, value);
 	if (status == 0) {
 		mcp->cache[MCP_IODIR] &= ~mask;
 		status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
 	}
 	mutex_unlock(&mcp->lock);
 	return status;
 }

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

 #ifdef CONFIG_DEBUG_FS

 #include <linux/seq_file.h>

 /*
  * This shows more info than the generic gpio dump code:
  * pullups, deglitching, open drain drive.
  */
 static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
 	struct mcp23s08	*mcp;
 	char		bank;
 	int		t;
 	unsigned	mask;

 	mcp = container_of(chip, struct mcp23s08, chip);

 	/* NOTE: we only handle one bank for now ... */
 	bank = '0' + ((mcp->addr >> 1) & 0x3);

 	mutex_lock(&mcp->lock);
 	t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 	if (t < 0) {
 		seq_printf(s, " I/O ERROR %d\n", t);
 		goto done;
 	}

 	for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
 		const char	*label;

 		label = gpiochip_is_requested(chip, t);
 		if (!label)
 			continue;

 		seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
 			chip->base + t, bank, t, label,
 			(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
 			(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
 			(mcp->cache[MCP_GPPU] & mask) ? "  " : "up");
 		/* NOTE:  ignoring the irq-related registers */
 		seq_printf(s, "\n");
 	}
 done:
 	mutex_unlock(&mcp->lock);
 }

 #else
 #define mcp23s08_dbg_show	NULL
 #endif

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

 static int mcp23s08_probe_one(struct spi_device *spi, unsigned addr,
 		unsigned base, unsigned pullups)
 {
 	struct mcp23s08_driver_data	*data = spi_get_drvdata(spi);
 	struct mcp23s08			*mcp = data->mcp[addr];
 	int				status;
 	int				do_update = 0;

 	mutex_init(&mcp->lock);

 	mcp->spi = spi;
 	mcp->addr = 0x40 | (addr << 1);

 	mcp->chip.label = "mcp23s08",

 	mcp->chip.direction_input = mcp23s08_direction_input;
 	mcp->chip.get = mcp23s08_get;
 	mcp->chip.direction_output = mcp23s08_direction_output;
 	mcp->chip.set = mcp23s08_set;
 	mcp->chip.dbg_show = mcp23s08_dbg_show;

 	mcp->chip.base = base;
 	mcp->chip.ngpio = 8;
 	mcp->chip.can_sleep = 1;
 	mcp->chip.dev = &spi->dev;
 	mcp->chip.owner = THIS_MODULE;

 	/* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
 	 * and MCP_IOCON.HAEN = 1, so we work with all chips.
 	 */
 	status = mcp23s08_read(mcp, MCP_IOCON);
 	if (status < 0)
 		goto fail;
 	if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN)) {
 		status &= ~IOCON_SEQOP;
 		status |= IOCON_HAEN;
 		status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
 		if (status < 0)
 			goto fail;
 	}

 	/* configure ~100K pullups */
 	status = mcp23s08_write(mcp, MCP_GPPU, pullups);
 	if (status < 0)
 		goto fail;

 	status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
 	if (status < 0)
 		goto fail;

 	/* disable inverter on input */
 	if (mcp->cache[MCP_IPOL] != 0) {
 		mcp->cache[MCP_IPOL] = 0;
 		do_update = 1;
 	}

 	/* disable irqs */
 	if (mcp->cache[MCP_GPINTEN] != 0) {
 		mcp->cache[MCP_GPINTEN] = 0;
 		do_update = 1;
 	}

 	if (do_update) {
 		u8 tx[4];

 		tx[0] = mcp->addr;
 		tx[1] = MCP_IPOL;
 		memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
 		status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
 		if (status < 0)
 			goto fail;
 	}

 	status = gpiochip_add(&mcp->chip);
 fail:
 	if (status < 0)
 		dev_dbg(&spi->dev, "can't setup chip %d, --> %d\n",
 				addr, status);
 	return status;
 }

 static int mcp23s08_probe(struct spi_device *spi)
 {
 	struct mcp23s08_platform_data	*pdata;
 	unsigned			addr;
 	unsigned			chips = 0;
 	struct mcp23s08_driver_data	*data;
 	int				status;
 	unsigned			base;

 	pdata = spi->dev.platform_data;
 	if (!pdata || !gpio_is_valid(pdata->base)) {
 		dev_dbg(&spi->dev, "invalid or missing platform data\n");
 		return -EINVAL;
 	}

 	for (addr = 0; addr < 4; addr++) {
 		if (!pdata->chip[addr].is_present)
 			continue;
 		chips++;
 	}
 	if (!chips)
 		return -ENODEV;

 	data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
 			GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 	spi_set_drvdata(spi, data);

 	base = pdata->base;
 	for (addr = 0; addr < 4; addr++) {
 		if (!pdata->chip[addr].is_present)
 			continue;
 		chips--;
 		data->mcp[addr] = &data->chip[chips];
 		status = mcp23s08_probe_one(spi, addr, base,
 				pdata->chip[addr].pullups);
 		if (status < 0)
 			goto fail;
 		base += 8;
 	}
 	data->ngpio = base - pdata->base;

 	/* NOTE:  these chips have a relatively sane IRQ framework, with
 	 * per-signal masking and level/edge triggering.  It's not yet
 	 * handled here...
 	 */

 	if (pdata->setup) {
 		status = pdata->setup(spi,
 				pdata->base, data->ngpio,
 				pdata->context);
 		if (status < 0)
 			dev_dbg(&spi->dev, "setup --> %d\n", status);
 	}

 	return 0;

 fail:
 	for (addr = 0; addr < 4; addr++) {
 		int tmp;

 		if (!data->mcp[addr])
 			continue;
 		tmp = gpiochip_remove(&data->mcp[addr]->chip);
 		if (tmp < 0)
 			dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
 	}
 	kfree(data);
 	return status;
 }

 static int mcp23s08_remove(struct spi_device *spi)
 {
 	struct mcp23s08_driver_data	*data = spi_get_drvdata(spi);
 	struct mcp23s08_platform_data	*pdata = spi->dev.platform_data;
 	unsigned			addr;
 	int				status = 0;

 	if (pdata->teardown) {
 		status = pdata->teardown(spi,
 				pdata->base, data->ngpio,
 				pdata->context);
 		if (status < 0) {
 			dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
 			return status;
 		}
 	}

 	for (addr = 0; addr < 4; addr++) {
 		int tmp;

 		if (!data->mcp[addr])
 			continue;

 		tmp = gpiochip_remove(&data->mcp[addr]->chip);
 		if (tmp < 0) {
 			dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
 			status = tmp;
 		}
 	}
 	if (status == 0)
 		kfree(data);
 	return status;
 }

 static struct spi_driver mcp23s08_driver = {
 	.probe		= mcp23s08_probe,
 	.remove		= mcp23s08_remove,
 	.driver = {
 		.name	= "mcp23s08",
 		.owner	= THIS_MODULE,
 	},
 };

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

 static int __init mcp23s08_init(void)
 {
 	return spi_register_driver(&mcp23s08_driver);
 }
 /* register after spi postcore initcall and before
  * subsys initcalls that may rely on these GPIOs
  */
 subsys_initcall(mcp23s08_init);

 static void __exit mcp23s08_exit(void)
 {
 	spi_unregister_driver(&mcp23s08_driver);
 }
 module_exit(mcp23s08_exit);

 MODULE_LICENSE("GPL");
	/*
	* mcp23s08.c - SPI gpio expander driver
	*/

	#include <linux/kernel.h>
	#include <linux/device.h>
	#include <linux/workqueue.h>
	#include <linux/mutex.h>

	#include <linux/spi/spi.h>
	#include <linux/spi/mcp23s08.h>

	#include <asm/gpio.h>


	/* Registers are all 8 bits wide.
	*
	* The mcp23s17 has twice as many bits, and can be configured to work
	* with either 16 bit registers or with two adjacent 8 bit banks.
	*
	* Also, there are I2C versions of both chips.
	*/
	#define MCP_IODIR 0x00 /* init/reset: all ones */
	#define MCP_IPOL 0x01
	#define MCP_GPINTEN 0x02
	#define MCP_DEFVAL 0x03
	#define MCP_INTCON 0x04
	#define MCP_IOCON 0x05
	# define IOCON_SEQOP (1 << 5)
	# define IOCON_HAEN (1 << 3)
	# define IOCON_ODR (1 << 2)
	# define IOCON_INTPOL (1 << 1)
	#define MCP_GPPU 0x06
	#define MCP_INTF 0x07
	#define MCP_INTCAP 0x08
	#define MCP_GPIO 0x09
	#define MCP_OLAT 0x0a

	struct mcp23s08 {
	struct spi_device *spi;
	u8 addr;

	u8 cache[11];
	/* lock protects the cached values */
	struct mutex lock;

	struct gpio_chip chip;

	struct work_struct work;
	};

	/* A given spi_device can represent up to four mcp23s08 chips
	* sharing the same chipselect but using different addresses
	* (e.g. chips #0 and #3 might be populated, but not #1 or $2).
	* Driver data holds all the per-chip data.
	*/
	struct mcp23s08_driver_data {
	unsigned ngpio;
	struct mcp23s08 *mcp[4];
	struct mcp23s08 chip[];
	};

	static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
	{
	u8 tx[2], rx[1];
	int status;

	tx[0] = mcp->addr \| 0x01;
	tx[1] = reg;
	status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
	return (status < 0) ? status : rx[0];
	}

	static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
	{
	u8 tx[3];

	tx[0] = mcp->addr;
	tx[1] = reg;
	tx[2] = val;
	return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
	}

	static int
	mcp23s08_read_regs(struct mcp23s08 mcp, unsigned reg, u8 vals, unsigned n)
	{
	u8 tx[2];

	if ((n + reg) > sizeof mcp->cache)
	return -EINVAL;
	tx[0] = mcp->addr \| 0x01;
	tx[1] = reg;
	return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
	}

	/----------------------------------------------------------------------/

	static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
	{
	struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
	int status;

	mutex_lock(&mcp->lock);
	mcp->cache[MCP_IODIR] \|= (1 << offset);
	status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
	mutex_unlock(&mcp->lock);
	return status;
	}

	static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
	{
	struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
	int status;

	mutex_lock(&mcp->lock);

	/* REVISIT reading this clears any IRQ ... */
	status = mcp23s08_read(mcp, MCP_GPIO);
	if (status < 0)
	status = 0;
	else {
	mcp->cache[MCP_GPIO] = status;
	status = !!(status & (1 << offset));
	}
	mutex_unlock(&mcp->lock);
	return status;
	}

	static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
	{
	u8 olat = mcp->cache[MCP_OLAT];

	if (value)
	olat \|= mask;
	else
	olat &= ~mask;
	mcp->cache[MCP_OLAT] = olat;
	return mcp23s08_write(mcp, MCP_OLAT, olat);
	}

	static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
	{
	struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
	u8 mask = 1 << offset;

	mutex_lock(&mcp->lock);
	__mcp23s08_set(mcp, mask, value);
	mutex_unlock(&mcp->lock);
	}

	static int
	mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
	{
	struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
	u8 mask = 1 << offset;
	int status;

	mutex_lock(&mcp->lock);
	status = __mcp23s08_set(mcp, mask, value);
	if (status == 0) {
	mcp->cache[MCP_IODIR] &= ~mask;
	status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
	}
	mutex_unlock(&mcp->lock);
	return status;
	}

	/----------------------------------------------------------------------/

	#ifdef CONFIG_DEBUG_FS

	#include <linux/seq_file.h>

	/*
	* This shows more info than the generic gpio dump code:
	* pullups, deglitching, open drain drive.
	*/
	static void mcp23s08_dbg_show(struct seq_file s, struct gpio_chip chip)
	{
	struct mcp23s08 *mcp;
	char bank;
	int t;
	unsigned mask;

	mcp = container_of(chip, struct mcp23s08, chip);

	/* NOTE: we only handle one bank for now ... */
	bank = '0' + ((mcp->addr >> 1) & 0x3);

	mutex_lock(&mcp->lock);
	t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
	if (t < 0) {
	seq_printf(s, " I/O ERROR %d\n", t);
	goto done;
	}

	for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
	const char *label;

	label = gpiochip_is_requested(chip, t);
	if (!label)
	continue;

	seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
	chip->base + t, bank, t, label,
	(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
	(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
	(mcp->cache[MCP_GPPU] & mask) ? " " : "up");
	/* NOTE: ignoring the irq-related registers */
	seq_printf(s, "\n");
	}
	done:
	mutex_unlock(&mcp->lock);
	}

	#else
	#define mcp23s08_dbg_show NULL
	#endif

	/----------------------------------------------------------------------/

	static int mcp23s08_probe_one(struct spi_device *spi, unsigned addr,
	unsigned base, unsigned pullups)
	{
	struct mcp23s08_driver_data *data = spi_get_drvdata(spi);
	struct mcp23s08 *mcp = data->mcp[addr];
	int status;
	int do_update = 0;

	mutex_init(&mcp->lock);

	mcp->spi = spi;
	mcp->addr = 0x40 \| (addr << 1);

	mcp->chip.label = "mcp23s08",

	mcp->chip.direction_input = mcp23s08_direction_input;
	mcp->chip.get = mcp23s08_get;
	mcp->chip.direction_output = mcp23s08_direction_output;
	mcp->chip.set = mcp23s08_set;
	mcp->chip.dbg_show = mcp23s08_dbg_show;

	mcp->chip.base = base;
	mcp->chip.ngpio = 8;
	mcp->chip.can_sleep = 1;
	mcp->chip.dev = &spi->dev;
	mcp->chip.owner = THIS_MODULE;

	/* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
	* and MCP_IOCON.HAEN = 1, so we work with all chips.
	*/
	status = mcp23s08_read(mcp, MCP_IOCON);
	if (status < 0)
	goto fail;
	if ((status & IOCON_SEQOP) \|\| !(status & IOCON_HAEN)) {
	status &= ~IOCON_SEQOP;
	status \|= IOCON_HAEN;
	status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
	if (status < 0)
	goto fail;
	}

	/* configure ~100K pullups */
	status = mcp23s08_write(mcp, MCP_GPPU, pullups);
	if (status < 0)
	goto fail;

	status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
	if (status < 0)
	goto fail;

	/* disable inverter on input */
	if (mcp->cache[MCP_IPOL] != 0) {
	mcp->cache[MCP_IPOL] = 0;
	do_update = 1;
	}

	/* disable irqs */
	if (mcp->cache[MCP_GPINTEN] != 0) {
	mcp->cache[MCP_GPINTEN] = 0;
	do_update = 1;
	}

	if (do_update) {
	u8 tx[4];

	tx[0] = mcp->addr;
	tx[1] = MCP_IPOL;
	memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
	status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
	if (status < 0)
	goto fail;
	}

	status = gpiochip_add(&mcp->chip);
	fail:
	if (status < 0)
	dev_dbg(&spi->dev, "can't setup chip %d, --> %d\n",
	addr, status);
	return status;
	}

	static int mcp23s08_probe(struct spi_device *spi)
	{
	struct mcp23s08_platform_data *pdata;
	unsigned addr;
	unsigned chips = 0;
	struct mcp23s08_driver_data *data;
	int status;
	unsigned base;

	pdata = spi->dev.platform_data;
	if (!pdata \|\| !gpio_is_valid(pdata->base)) {
	dev_dbg(&spi->dev, "invalid or missing platform data\n");
	return -EINVAL;
	}

	for (addr = 0; addr < 4; addr++) {
	if (!pdata->chip[addr].is_present)
	continue;
	chips++;
	}
	if (!chips)
	return -ENODEV;

	data = kzalloc(sizeof data + chips sizeof(struct mcp23s08),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;
	spi_set_drvdata(spi, data);

	base = pdata->base;
	for (addr = 0; addr < 4; addr++) {
	if (!pdata->chip[addr].is_present)
	continue;
	chips--;
	data->mcp[addr] = &data->chip[chips];
	status = mcp23s08_probe_one(spi, addr, base,
	pdata->chip[addr].pullups);
	if (status < 0)
	goto fail;
	base += 8;
	}
	data->ngpio = base - pdata->base;

	/* NOTE: these chips have a relatively sane IRQ framework, with
	* per-signal masking and level/edge triggering. It's not yet
	* handled here...
	*/

	if (pdata->setup) {
	status = pdata->setup(spi,
	pdata->base, data->ngpio,
	pdata->context);
	if (status < 0)
	dev_dbg(&spi->dev, "setup --> %d\n", status);
	}

	return 0;

	fail:
	for (addr = 0; addr < 4; addr++) {
	int tmp;

	if (!data->mcp[addr])
	continue;
	tmp = gpiochip_remove(&data->mcp[addr]->chip);
	if (tmp < 0)
	dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
	}
	kfree(data);
	return status;
	}

	static int mcp23s08_remove(struct spi_device *spi)
	{
	struct mcp23s08_driver_data *data = spi_get_drvdata(spi);
	struct mcp23s08_platform_data *pdata = spi->dev.platform_data;
	unsigned addr;
	int status = 0;

	if (pdata->teardown) {
	status = pdata->teardown(spi,
	pdata->base, data->ngpio,
	pdata->context);
	if (status < 0) {
	dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
	return status;
	}
	}

	for (addr = 0; addr < 4; addr++) {
	int tmp;

	if (!data->mcp[addr])
	continue;

	tmp = gpiochip_remove(&data->mcp[addr]->chip);
	if (tmp < 0) {
	dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
	status = tmp;
	}
	}
	if (status == 0)
	kfree(data);
	return status;
	}

	static struct spi_driver mcp23s08_driver = {
	.probe = mcp23s08_probe,
	.remove = mcp23s08_remove,
	.driver = {
	.name = "mcp23s08",
	.owner = THIS_MODULE,
	},
	};

	/----------------------------------------------------------------------/

	static int __init mcp23s08_init(void)
	{
	return spi_register_driver(&mcp23s08_driver);
	}
	/* register after spi postcore initcall and before
	* subsys initcalls that may rely on these GPIOs
	*/
	subsys_initcall(mcp23s08_init);

	static void __exit mcp23s08_exit(void)
	{
	spi_unregister_driver(&mcp23s08_driver);
	}
	module_exit(mcp23s08_exit);

	MODULE_LICENSE("GPL");