/*
 * MCP23S08 SPI/I2C GPIO gpio expander driver
 *
 * The inputs and outputs of the mcp23s08, mcp23s17, mcp23008 and mcp23017 are
 * supported.
 * For the I2C versions of the chips (mcp23008 and mcp23017) generation of
 * interrupts is also supported.
 * The hardware of the SPI versions of the chips (mcp23s08 and mcp23s17) is
 * also capable of generating interrupts, but the linux driver does not
 * support that yet.
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/spi/spi.h>
#include <linux/spi/mcp23s08.h>
#include <linux/slab.h>
#include <asm/byteorder.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/of_device.h>

/**
 * MCP types supported by driver
 */
#define MCP_TYPE_S08	0
#define MCP_TYPE_S17	1
#define MCP_TYPE_008	2
#define MCP_TYPE_017	3

/* 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.
 */
#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_MIRROR	(1 << 6)
#	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 mcp23s08_ops {
	int	(*read)(struct mcp23s08 *mcp, unsigned reg);
	int	(*write)(struct mcp23s08 *mcp, unsigned reg, unsigned val);
	int	(*read_regs)(struct mcp23s08 *mcp, unsigned reg,
			     u16 *vals, unsigned n);
};

struct mcp23s08 {
	u8			addr;

	u16			cache[11];
	u16			irq_rise;
	u16			irq_fall;
	int			irq;
	bool			irq_controller;
	/* lock protects the cached values */
	struct mutex		lock;
	struct mutex		irq_lock;
	struct irq_domain	*irq_domain;

	struct gpio_chip	chip;

	const struct mcp23s08_ops	*ops;
	void			*data; /* ops specific data */
};

/* A given spi_device can represent up to eight mcp23sxx 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[8];
	struct mcp23s08		chip[];
};

/* This lock class tells lockdep that GPIO irqs are in a different
 * category than their parents, so it won't report false recursion.
 */
static struct lock_class_key gpio_lock_class;

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

#if IS_ENABLED(CONFIG_I2C)

static int mcp23008_read(struct mcp23s08 *mcp, unsigned reg)
{
	return i2c_smbus_read_byte_data(mcp->data, reg);
}

static int mcp23008_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
	return i2c_smbus_write_byte_data(mcp->data, reg, val);
}

static int
mcp23008_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
	while (n--) {
		int ret = mcp23008_read(mcp, reg++);
		if (ret < 0)
			return ret;
		*vals++ = ret;
	}

	return 0;
}

static int mcp23017_read(struct mcp23s08 *mcp, unsigned reg)
{
	return i2c_smbus_read_word_data(mcp->data, reg << 1);
}

static int mcp23017_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
	return i2c_smbus_write_word_data(mcp->data, reg << 1, val);
}

static int
mcp23017_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
	while (n--) {
		int ret = mcp23017_read(mcp, reg++);
		if (ret < 0)
			return ret;
		*vals++ = ret;
	}

	return 0;
}

static const struct mcp23s08_ops mcp23008_ops = {
	.read		= mcp23008_read,
	.write		= mcp23008_write,
	.read_regs	= mcp23008_read_regs,
};

static const struct mcp23s08_ops mcp23017_ops = {
	.read		= mcp23017_read,
	.write		= mcp23017_write,
	.read_regs	= mcp23017_read_regs,
};

#endif /* CONFIG_I2C */

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

#ifdef CONFIG_SPI_MASTER

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

	tx[0]