drivers/gpio/gpio_pcal9535a.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2015 Intel Corporation.
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 /**
  * @file Driver for PCAL9535A I2C-based GPIO driver.
  */

 #include <errno.h>

 #include <kernel.h>
 #include <device.h>
 #include <init.h>
 #include <misc/util.h>
 #include <gpio.h>
 #include <i2c.h>

 #include "gpio_pcal9535a.h"

 #define LOG_LEVEL CONFIG_GPIO_LOG_LEVEL
 #include <logging/log.h>
 LOG_MODULE_REGISTER(gpio_pcal9535a);

 /* Register definitions */
 #define REG_INPUT_PORT0			0x00
 #define REG_INPUT_PORT1			0x01
 #define REG_OUTPUT_PORT0		0x02
 #define REG_OUTPUT_PORT1		0x03
 #define REG_POL_INV_PORT0		0x04
 #define REG_POL_INV_PORT1		0x05
 #define REG_CONF_PORT0			0x06
 #define REG_CONG_PORT1			0x07
 #define REG_OUT_DRV_STRENGTH_PORT0_L	0x40
 #define REG_OUT_DRV_STRENGTH_PORT0_H	0x41
 #define REG_OUT_DRV_STRENGTH_PORT1_L	0x42
 #define REG_OUT_DRV_STRENGTH_PORT1_H	0x43
 #define REG_INPUT_LATCH_PORT0		0x44
 #define REG_INPUT_LATCH_PORT1		0x45
 #define REG_PUD_EN_PORT0		0x46
 #define REG_PUD_EN_PORT1		0x47
 #define REG_PUD_SEL_PORT0		0x48
 #define REG_PUD_SEL_PORT1		0x49
 #define REG_INT_MASK_PORT0		0x4A
 #define REG_INT_MASK_PORT1		0x4B
 #define REG_INT_STATUS_PORT0		0x4C
 #define REG_INT_STATUS_PORT1		0x4D
 #define REG_OUTPUT_PORT_CONF		0x4F

 /**
  * @brief Check to see if a I2C master is identified for communication.
  *
  * @param dev Device struct.
  * @return 1 if I2C master is identified, 0 if not.
  */
 static inline int _has_i2c_master(struct device *dev)
 {
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	struct device * const i2c_master = drv_data->i2c_master;

 	if (i2c_master)
 		return 1;
 	else
 		return 0;
 }

 /**
  * @brief Read both port 0 and port 1 registers of certain register function.
  *
  * Given the register in reg, read the pair of port 0 and port 1.
  *
  * @param dev Device struct of the PCAL9535A.
  * @param reg Register to read (the PORT0 of the pair of registers).
  * @param buf Buffer to read data into.
  *
  * @return 0 if successful, failed otherwise.
  */
 static int _read_port_regs(struct device *dev, u8_t reg,
 			   union gpio_pcal9535a_port_data *buf)
 {
 	const struct gpio_pcal9535a_config * const config =
 		dev->config->config_info;
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	struct device * const i2c_master = drv_data->i2c_master;
 	u16_t i2c_addr = config->i2c_slave_addr;
 	int ret;

 	ret = i2c_burst_read(i2c_master, i2c_addr, reg, buf->byte, 2);
 	if (ret) {
 		LOG_ERR("PCAL9535A[0x%X]: error reading register 0x%X (%d)",
 			i2c_addr, reg, ret);
 		goto error;
 	}

 	LOG_DBG("PCAL9535A[0x%X]: Read: REG[0x%X] = 0x%X, REG[0x%X] = 0x%X",
 		i2c_addr, reg, buf->byte[0], (reg + 1), buf->byte[1]);

 error:
 	return ret;
 }

 /**
  * @brief Write both port 0 and port 1 registers of certain register function.
  *
  * Given the register in reg, write the pair of port 0 and port 1.
  *
  * @param dev Device struct of the PCAL9535A.
  * @param reg Register to write into (the PORT0 of the pair of registers).
  * @param buf Buffer to write data from.
  *
  * @return 0 if successful, failed otherwise.
  */
 static int _write_port_regs(struct device *dev, u8_t reg,
 			    union gpio_pcal9535a_port_data *buf)
 {
 	const struct gpio_pcal9535a_config * const config =
 		dev->config->config_info;
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	struct device * const i2c_master = drv_data->i2c_master;
 	u16_t i2c_addr = config->i2c_slave_addr;
 	int ret;

 	LOG_DBG("PCAL9535A[0x%X]: Write: REG[0x%X] = 0x%X, REG[0x%X] = "
 		"0x%X", i2c_addr, reg, buf->byte[0], (reg + 1),
 		buf->byte[1]);

 	ret = i2c_burst_write(i2c_master, i2c_addr, reg, buf->byte, 2);
 	if (ret) {
 		LOG_ERR("PCAL9535A[0x%X]: error writing from register 0x%X "
 			"(%d)", i2c_addr, reg, ret);
 	}

 	return ret;
 }

 /**
  * @brief Setup the pin direction (input or output)
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param flags Flags of pin or port
  *
  * @return 0 if successful, failed otherwise
  */
 static int _setup_pin_dir(struct device *dev, int access_op,
 			  u32_t pin, int flags)
 {
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.dir;
 	u16_t bit_mask;
 	u16_t new_value = 0U;
 	int ret;

 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		bit_mask = 1 << pin;

 		/* Config 0 == output, 1 == input */
 		if ((flags & GPIO_DIR_MASK) == GPIO_DIR_IN) {
 			new_value = 1 << pin;
 		}

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	case GPIO_ACCESS_BY_PORT:
 		/* Config 0 == output, 1 == input */
 		if ((flags & GPIO_DIR_MASK) == GPIO_DIR_IN) {
 			port->all = 0xFFFF;
 		} else {
 			port->all = 0x0;
 		}
 		break;
 	default:
 		ret = -ENOTSUP;
 		goto done;
 	}

 	ret = _write_port_regs(dev, REG_CONF_PORT0, port);

 done:
 	return ret;
 }

 /**
  * @brief Setup the pin pull up/pull down status
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param flags Flags of pin or port
  *
  * @return 0 if successful, failed otherwise
  */
 static int _setup_pin_pullupdown(struct device *dev, int access_op,
 				 u32_t pin, int flags)
 {
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	union gpio_pcal9535a_port_data *port;
 	u16_t bit_mask;
 	u16_t new_value = 0U;
 	int ret;

 	/* If disabling pull up/down, there is no need to set the selection
 	 * register. Just go straight to disabling.
 	 */
 	if ((flags & GPIO_PUD_MASK) == GPIO_PUD_NORMAL) {
 		goto en_dis;
 	}

 	/* Setup pin pull up or pull down */
 	port = &drv_data->reg_cache.pud_sel;
 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		bit_mask = 1 << pin;

 		/* pull down == 0, pull up == 1*/
 		if ((flags & GPIO_PUD_MASK) == GPIO_PUD_PULL_UP) {
 			new_value = 1 << pin;
 		}

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	case GPIO_ACCESS_BY_PORT:
 		/* pull down == 0, pull up == 1*/
 		if ((flags & GPIO_PUD_MASK) == GPIO_PUD_PULL_UP) {
 			port->all = 0xFFFF;
 		} else {
 			port->all = 0x0;
 		}
 		break;
 	default:
 		ret = -ENOTSUP;
 		goto done;
 	}

 	ret = _write_port_regs(dev, REG_PUD_SEL_PORT0, port);
 	if (ret) {
 		goto done;
 	}

 en_dis:
 	/* enable/disable pull up/down */
 	port = &drv_data->reg_cache.pud_en;
 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		bit_mask = 1 << pin;

 		if ((flags & GPIO_PUD_MASK) != GPIO_PUD_NORMAL) {
 			new_value = 1 << pin;
 		}

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	case GPIO_ACCESS_BY_PORT:
 		if ((flags & GPIO_PUD_MASK) != GPIO_PUD_NORMAL) {
 			port->all = 0xFFFF;
 		} else {
 			port->all = 0x0;
 		}
 		break;
 	default:
 		ret = -ENOTSUP;
 		goto done;
 	}

 	ret = _write_port_regs(dev, REG_PUD_EN_PORT0, port);

 done:
 	return ret;
 }

 /**
  * @brief Setup the polarity of pin or port
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param flags Flags of pin or port
  *
  * @return 0 if successful, failed otherwise
  */
 static int _setup_pin_polarity(struct device *dev, int access_op,
 			       u32_t pin, int flags)
 {
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.pol_inv;
 	u16_t bit_mask;
 	u16_t new_value = 0U;
 	int ret;

 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		bit_mask = BIT(pin);

 		/* normal == 0, invert == 1 */
 		if ((flags & GPIO_POL_MASK) == GPIO_POL_INV) {
 			new_value = BIT(pin);
 		}

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	case GPIO_ACCESS_BY_PORT:
 		/* normal == 0, invert == 1 */
 		if ((flags & GPIO_POL_MASK) == GPIO_POL_INV) {
 			port->all = 0xFFFF;
 		} else {
 			port->all = 0x0;
 		}
 		break;
 	default:
 		ret = -ENOTSUP;
 		goto done;
 	}

 	ret = _write_port_regs(dev, REG_POL_INV_PORT0, port);
 	if (!ret) {
 		drv_data->out_pol_inv = port->all;
 	}

 done:
 	return ret;
 }

 /**
  * @brief Configure pin or port
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param flags Flags of pin or port
  *
  * @return 0 if successful, failed otherwise
  */
 static int gpio_pcal9535a_config(struct device *dev, int access_op,
 				 u32_t pin, int flags)
 {
 	int ret;

 #if (CONFIG_GPIO_LOG_LEVEL >= LOG_LEVEL_DEBUG)
 	const struct gpio_pcal9535a_config * const config =
 		dev->config->config_info;
 	u16_t i2c_addr = config->i2c_slave_addr;
 #endif

 	if (flags & GPIO_INT) {
 		return -ENOTSUP;
 	}

 	if (!_has_i2c_master(dev)) {
 		return -EINVAL;
 	}

 	ret = _setup_pin_dir(dev, access_op, pin, flags);
 	if (ret) {
 		LOG_ERR("PCAL9535A[0x%X]: error setting pin direction (%d)",
 			i2c_addr, ret);
 		goto done;
 	}

 	ret = _setup_pin_polarity(dev, access_op, pin, flags);
 	if (ret) {
 		LOG_ERR("PCAL9535A[0x%X]: error setting pin polarity (%d)",
 			i2c_addr, ret);
 		goto done;
 	}

 	ret = _setup_pin_pullupdown(dev, access_op, pin, flags);
 	if (ret) {
 		LOG_ERR("PCAL9535A[0x%X]: error setting pin pull up/down "
 			"(%d)", i2c_addr, ret);
 		goto done;
 	}

 done:
 	return ret;
 }

 /**
  * @brief Set the pin or port output
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param value Value to set (0 or 1)
  *
  * @return 0 if successful, failed otherwise
  */
 static int gpio_pcal9535a_write(struct device *dev, int access_op,
 				u32_t pin, u32_t value)
 {
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.output;
 	u16_t bit_mask;
 	u16_t new_value;
 	int ret;

 	if (!_has_i2c_master(dev)) {
 		return -EINVAL;
 	}

 	/* Invert input value for pins configurated as active low. */
 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		bit_mask = BIT(pin);

 		new_value = (value << pin) & bit_mask;
 		new_value ^= (drv_data->out_pol_inv & bit_mask);
 		new_value &= bit_mask;

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	case GPIO_ACCESS_BY_PORT:
 		port->all = value;
 		bit_mask = drv_data->out_pol_inv;

 		new_value = value & bit_mask;
 		new_value ^= drv_data->out_pol_inv;
 		new_value &= bit_mask;

 		port->all &= ~bit_mask;
 		port->all |= new_value;

 		break;
 	default:
 		ret = -ENOTSUP;
 		goto done;
 	}

 	ret = _write_port_regs(dev, REG_OUTPUT_PORT0, port);

 done:
 	return ret;
 }

 /**
  * @brief Read the pin or port status
  *
  * @param dev Device struct of the PCAL9535A
  * @param access_op Access operation (pin or port)
  * @param pin The pin number
  * @param value Value of input pin(s)
  *
  * @return 0 if successful, failed otherwise
  */
 static int gpio_pcal9535a_read(struct device *dev, int access_op,
 			       u32_t pin, u32_t *value)
 {
 	union gpio_pcal9535a_port_data buf;
 	int ret;

 	if (!_has_i2c_master(dev)) {
 		return -EINVAL;
 	}

 	ret = _read_port_regs(dev, REG_INPUT_PORT0, &buf);
 	if (ret != 0) {
 		goto done;
 	}

 	switch (access_op) {
 	case GPIO_ACCESS_BY_PIN:
 		*value = (buf.all >> pin) & 0x01;
 		break;
 	case GPIO_ACCESS_BY_PORT:
 		*value = buf.all;
 		break;
 	default:
 		ret = -ENOTSUP;
 		break;
 	}

 done:
 	return ret;
 }

 static const struct gpio_driver_api gpio_pcal9535a_drv_api_funcs = {
 	.config = gpio_pcal9535a_config,
 	.write = gpio_pcal9535a_write,
 	.read = gpio_pcal9535a_read,
 };

 /**
  * @brief Initialization function of PCAL9535A
  *
  * @param dev Device struct
  * @return 0 if successful, failed otherwise.
  */
 static int gpio_pcal9535a_init(struct device *dev)
 {
 	const struct gpio_pcal9535a_config * const config =
 		dev->config->config_info;
 	struct gpio_pcal9535a_drv_data * const drv_data =
 		(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
 	struct device *i2c_master;

 	/* Find out the device struct of the I2C master */
 	i2c_master = device_get_binding((char *)config->i2c_master_dev_name);
 	if (!i2c_master) {
 		return -EINVAL;
 	}
 	drv_data->i2c_master = i2c_master;

 	return 0;
 }

 /* Initialization for PCAL9535A_0 */
 #ifdef CONFIG_GPIO_PCAL9535A_0
 static const struct gpio_pcal9535a_config gpio_pcal9535a_0_cfg = {
 	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_0_I2C_MASTER_DEV_NAME,
 	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_0_I2C_ADDR,
 };

 static struct gpio_pcal9535a_drv_data gpio_pcal9535a_0_drvdata = {
 	/* Default for registers according to datasheet */
 	.reg_cache.output = { .all = 0xFFFF },
 	.reg_cache.pol_inv = { .all = 0x0 },
 	.reg_cache.dir = { .all = 0xFFFF },
 	.reg_cache.pud_en = { .all = 0x0 },
 	.reg_cache.pud_sel = { .all = 0xFFFF },
 };

 /* This has to init after I2C master */
 DEVICE_AND_API_INIT(gpio_pcal9535a_0, CONFIG_GPIO_PCAL9535A_0_DEV_NAME,
 	    gpio_pcal9535a_init,
 	    &gpio_pcal9535a_0_drvdata, &gpio_pcal9535a_0_cfg,
 	    POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
 	    &gpio_pcal9535a_drv_api_funcs);

 #endif /* CONFIG_GPIO_PCAL9535A_0 */

 /* Initialization for PCAL9535A_1 */
 #ifdef CONFIG_GPIO_PCAL9535A_1
 static const struct gpio_pcal9535a_config gpio_pcal9535a_1_cfg = {
 	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_1_I2C_MASTER_DEV_NAME,
 	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_1_I2C_ADDR,
 };

 static struct gpio_pcal9535a_drv_data gpio_pcal9535a_1_drvdata = {
 	/* Default for registers according to datasheet */
 	.reg_cache.output = { .all = 0xFFFF },
 	.reg_cache.pol_inv = { .all = 0x0 },
 	.reg_cache.dir = { .all = 0xFFFF },
 	.reg_cache.pud_en = { .all = 0x0 },
 	.reg_cache.pud_sel = { .all = 0xFFFF },
 };

 /* This has to init after I2C master */
 DEVICE_AND_API_INIT(gpio_pcal9535a_1, CONFIG_GPIO_PCAL9535A_1_DEV_NAME,
 	    gpio_pcal9535a_init,
 	    &gpio_pcal9535a_1_drvdata, &gpio_pcal9535a_1_cfg,
 	    POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
 	    &gpio_pcal9535a_drv_api_funcs);

 #endif /* CONFIG_GPIO_PCAL9535A_1 */

 /* Initialization for PCAL9535A_2 */
 #ifdef CONFIG_GPIO_PCAL9535A_2
 static const struct gpio_pcal9535a_config gpio_pcal9535a_2_cfg = {
 	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_2_I2C_MASTER_DEV_NAME,
 	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_2_I2C_ADDR,
 };

 static struct gpio_pcal9535a_drv_data gpio_pcal9535a_2_drvdata = {
 	/* Default for registers according to datasheet */
 	.reg_cache.output = { .all = 0xFFFF },
 	.reg_cache.pol_inv = { .all = 0x0 },
 	.reg_cache.dir = { .all = 0xFFFF },
 	.reg_cache.pud_en = { .all = 0x0 },
 	.reg_cache.pud_sel = { .all = 0xFFFF },
 };

 /* This has to init after I2C master */
 DEVICE_AND_API_INIT(gpio_pcal9535a_2, CONFIG_GPIO_PCAL9535A_2_DEV_NAME,
 	    gpio_pcal9535a_init,
 	    &gpio_pcal9535a_2_drvdata, &gpio_pcal9535a_2_cfg,
 	    POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
 	    &gpio_pcal9535a_drv_api_funcs);

 #endif /* CONFIG_GPIO_PCAL9535A_2 */

 /* Initialization for PCAL9535A_3 */
 #ifdef CONFIG_GPIO_PCAL9535A_3
 static const struct gpio_pcal9535a_config gpio_pcal9535a_3_cfg = {
 	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_3_I2C_MASTER_DEV_NAME,
 	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_3_I2C_ADDR,
 };

 static struct gpio_pcal9535a_drv_data gpio_pcal9535a_3_drvdata = {
 	/* Default for registers according to datasheet */
 	.reg_cache.output = { .all = 0xFFFF },
 	.reg_cache.pol_inv = { .all = 0x0 },
 	.reg_cache.dir = { .all = 0xFFFF },
 	.reg_cache.pud_en = { .all = 0x0 },
 	.reg_cache.pud_sel = { .all = 0xFFFF },
 };

 /* This has to init after I2C master */
 DEVICE_AND_API_INIT(gpio_pcal9535a_3, CONFIG_GPIO_PCAL9535A_3_DEV_NAME,
 	    gpio_pcal9535a_init,
 	    &gpio_pcal9535a_3_drvdata, &gpio_pcal9535a_3_cfg,
 	    POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
 	    &gpio_pcal9535a_drv_api_funcs);

 #endif /* CONFIG_GPIO_PCAL9535A_3 */
	/*
	* Copyright (c) 2015 Intel Corporation.
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	/**
	* @file Driver for PCAL9535A I2C-based GPIO driver.
	*/

	#include <errno.h>

	#include <kernel.h>
	#include <device.h>
	#include <init.h>
	#include <misc/util.h>
	#include <gpio.h>
	#include <i2c.h>

	#include "gpio_pcal9535a.h"

	#define LOG_LEVEL CONFIG_GPIO_LOG_LEVEL
	#include <logging/log.h>
	LOG_MODULE_REGISTER(gpio_pcal9535a);

	/* Register definitions */
	#define REG_INPUT_PORT0 0x00
	#define REG_INPUT_PORT1 0x01
	#define REG_OUTPUT_PORT0 0x02
	#define REG_OUTPUT_PORT1 0x03
	#define REG_POL_INV_PORT0 0x04
	#define REG_POL_INV_PORT1 0x05
	#define REG_CONF_PORT0 0x06
	#define REG_CONG_PORT1 0x07
	#define REG_OUT_DRV_STRENGTH_PORT0_L 0x40
	#define REG_OUT_DRV_STRENGTH_PORT0_H 0x41
	#define REG_OUT_DRV_STRENGTH_PORT1_L 0x42
	#define REG_OUT_DRV_STRENGTH_PORT1_H 0x43
	#define REG_INPUT_LATCH_PORT0 0x44
	#define REG_INPUT_LATCH_PORT1 0x45
	#define REG_PUD_EN_PORT0 0x46
	#define REG_PUD_EN_PORT1 0x47
	#define REG_PUD_SEL_PORT0 0x48
	#define REG_PUD_SEL_PORT1 0x49
	#define REG_INT_MASK_PORT0 0x4A
	#define REG_INT_MASK_PORT1 0x4B
	#define REG_INT_STATUS_PORT0 0x4C
	#define REG_INT_STATUS_PORT1 0x4D
	#define REG_OUTPUT_PORT_CONF 0x4F

	/**
	* @brief Check to see if a I2C master is identified for communication.
	*
	* @param dev Device struct.
	* @return 1 if I2C master is identified, 0 if not.
	*/
	static inline int _has_i2c_master(struct device *dev)
	{
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	struct device * const i2c_master = drv_data->i2c_master;

	if (i2c_master)
	return 1;
	else
	return 0;
	}

	/**
	* @brief Read both port 0 and port 1 registers of certain register function.
	*
	* Given the register in reg, read the pair of port 0 and port 1.
	*
	* @param dev Device struct of the PCAL9535A.
	* @param reg Register to read (the PORT0 of the pair of registers).
	* @param buf Buffer to read data into.
	*
	* @return 0 if successful, failed otherwise.
	*/
	static int _read_port_regs(struct device *dev, u8_t reg,
	union gpio_pcal9535a_port_data *buf)
	{
	const struct gpio_pcal9535a_config * const config =
	dev->config->config_info;
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	struct device * const i2c_master = drv_data->i2c_master;
	u16_t i2c_addr = config->i2c_slave_addr;
	int ret;

	ret = i2c_burst_read(i2c_master, i2c_addr, reg, buf->byte, 2);
	if (ret) {
	LOG_ERR("PCAL9535A[0x%X]: error reading register 0x%X (%d)",
	i2c_addr, reg, ret);
	goto error;
	}

	LOG_DBG("PCAL9535A[0x%X]: Read: REG[0x%X] = 0x%X, REG[0x%X] = 0x%X",
	i2c_addr, reg, buf->byte[0], (reg + 1), buf->byte[1]);

	error:
	return ret;
	}

	/**
	* @brief Write both port 0 and port 1 registers of certain register function.
	*
	* Given the register in reg, write the pair of port 0 and port 1.
	*
	* @param dev Device struct of the PCAL9535A.
	* @param reg Register to write into (the PORT0 of the pair of registers).
	* @param buf Buffer to write data from.
	*
	* @return 0 if successful, failed otherwise.
	*/
	static int _write_port_regs(struct device *dev, u8_t reg,
	union gpio_pcal9535a_port_data *buf)
	{
	const struct gpio_pcal9535a_config * const config =
	dev->config->config_info;
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	struct device * const i2c_master = drv_data->i2c_master;
	u16_t i2c_addr = config->i2c_slave_addr;
	int ret;

	LOG_DBG("PCAL9535A[0x%X]: Write: REG[0x%X] = 0x%X, REG[0x%X] = "
	"0x%X", i2c_addr, reg, buf->byte[0], (reg + 1),
	buf->byte[1]);

	ret = i2c_burst_write(i2c_master, i2c_addr, reg, buf->byte, 2);
	if (ret) {
	LOG_ERR("PCAL9535A[0x%X]: error writing from register 0x%X "
	"(%d)", i2c_addr, reg, ret);
	}

	return ret;
	}

	/**
	* @brief Setup the pin direction (input or output)
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param flags Flags of pin or port
	*
	* @return 0 if successful, failed otherwise
	*/
	static int _setup_pin_dir(struct device *dev, int access_op,
	u32_t pin, int flags)
	{
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.dir;
	u16_t bit_mask;
	u16_t new_value = 0U;
	int ret;

	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	bit_mask = 1 << pin;

	/* Config 0 == output, 1 == input */
	if ((flags & GPIO_DIR_MASK) == GPIO_DIR_IN) {
	new_value = 1 << pin;
	}

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	case GPIO_ACCESS_BY_PORT:
	/* Config 0 == output, 1 == input */
	if ((flags & GPIO_DIR_MASK) == GPIO_DIR_IN) {
	port->all = 0xFFFF;
	} else {
	port->all = 0x0;
	}
	break;
	default:
	ret = -ENOTSUP;
	goto done;
	}

	ret = _write_port_regs(dev, REG_CONF_PORT0, port);

	done:
	return ret;
	}

	/**
	* @brief Setup the pin pull up/pull down status
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param flags Flags of pin or port
	*
	* @return 0 if successful, failed otherwise
	*/
	static int _setup_pin_pullupdown(struct device *dev, int access_op,
	u32_t pin, int flags)
	{
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	union gpio_pcal9535a_port_data *port;
	u16_t bit_mask;
	u16_t new_value = 0U;
	int ret;

	/* If disabling pull up/down, there is no need to set the selection
	* register. Just go straight to disabling.
	*/
	if ((flags & GPIO_PUD_MASK) == GPIO_PUD_NORMAL) {
	goto en_dis;
	}

	/* Setup pin pull up or pull down */
	port = &drv_data->reg_cache.pud_sel;
	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	bit_mask = 1 << pin;

	/* pull down == 0, pull up == 1*/
	if ((flags & GPIO_PUD_MASK) == GPIO_PUD_PULL_UP) {
	new_value = 1 << pin;
	}

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	case GPIO_ACCESS_BY_PORT:
	/* pull down == 0, pull up == 1*/
	if ((flags & GPIO_PUD_MASK) == GPIO_PUD_PULL_UP) {
	port->all = 0xFFFF;
	} else {
	port->all = 0x0;
	}
	break;
	default:
	ret = -ENOTSUP;
	goto done;
	}

	ret = _write_port_regs(dev, REG_PUD_SEL_PORT0, port);
	if (ret) {
	goto done;
	}

	en_dis:
	/* enable/disable pull up/down */
	port = &drv_data->reg_cache.pud_en;
	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	bit_mask = 1 << pin;

	if ((flags & GPIO_PUD_MASK) != GPIO_PUD_NORMAL) {
	new_value = 1 << pin;
	}

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	case GPIO_ACCESS_BY_PORT:
	if ((flags & GPIO_PUD_MASK) != GPIO_PUD_NORMAL) {
	port->all = 0xFFFF;
	} else {
	port->all = 0x0;
	}
	break;
	default:
	ret = -ENOTSUP;
	goto done;
	}

	ret = _write_port_regs(dev, REG_PUD_EN_PORT0, port);

	done:
	return ret;
	}

	/**
	* @brief Setup the polarity of pin or port
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param flags Flags of pin or port
	*
	* @return 0 if successful, failed otherwise
	*/
	static int _setup_pin_polarity(struct device *dev, int access_op,
	u32_t pin, int flags)
	{
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.pol_inv;
	u16_t bit_mask;
	u16_t new_value = 0U;
	int ret;

	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	bit_mask = BIT(pin);

	/* normal == 0, invert == 1 */
	if ((flags & GPIO_POL_MASK) == GPIO_POL_INV) {
	new_value = BIT(pin);
	}

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	case GPIO_ACCESS_BY_PORT:
	/* normal == 0, invert == 1 */
	if ((flags & GPIO_POL_MASK) == GPIO_POL_INV) {
	port->all = 0xFFFF;
	} else {
	port->all = 0x0;
	}
	break;
	default:
	ret = -ENOTSUP;
	goto done;
	}

	ret = _write_port_regs(dev, REG_POL_INV_PORT0, port);
	if (!ret) {
	drv_data->out_pol_inv = port->all;
	}

	done:
	return ret;
	}

	/**
	* @brief Configure pin or port
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param flags Flags of pin or port
	*
	* @return 0 if successful, failed otherwise
	*/
	static int gpio_pcal9535a_config(struct device *dev, int access_op,
	u32_t pin, int flags)
	{
	int ret;

	#if (CONFIG_GPIO_LOG_LEVEL >= LOG_LEVEL_DEBUG)
	const struct gpio_pcal9535a_config * const config =
	dev->config->config_info;
	u16_t i2c_addr = config->i2c_slave_addr;
	#endif

	if (flags & GPIO_INT) {
	return -ENOTSUP;
	}

	if (!_has_i2c_master(dev)) {
	return -EINVAL;
	}

	ret = _setup_pin_dir(dev, access_op, pin, flags);
	if (ret) {
	LOG_ERR("PCAL9535A[0x%X]: error setting pin direction (%d)",
	i2c_addr, ret);
	goto done;
	}

	ret = _setup_pin_polarity(dev, access_op, pin, flags);
	if (ret) {
	LOG_ERR("PCAL9535A[0x%X]: error setting pin polarity (%d)",
	i2c_addr, ret);
	goto done;
	}

	ret = _setup_pin_pullupdown(dev, access_op, pin, flags);
	if (ret) {
	LOG_ERR("PCAL9535A[0x%X]: error setting pin pull up/down "
	"(%d)", i2c_addr, ret);
	goto done;
	}

	done:
	return ret;
	}

	/**
	* @brief Set the pin or port output
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param value Value to set (0 or 1)
	*
	* @return 0 if successful, failed otherwise
	*/
	static int gpio_pcal9535a_write(struct device *dev, int access_op,
	u32_t pin, u32_t value)
	{
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	union gpio_pcal9535a_port_data *port = &drv_data->reg_cache.output;
	u16_t bit_mask;
	u16_t new_value;
	int ret;

	if (!_has_i2c_master(dev)) {
	return -EINVAL;
	}

	/* Invert input value for pins configurated as active low. */
	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	bit_mask = BIT(pin);

	new_value = (value << pin) & bit_mask;
	new_value ^= (drv_data->out_pol_inv & bit_mask);
	new_value &= bit_mask;

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	case GPIO_ACCESS_BY_PORT:
	port->all = value;
	bit_mask = drv_data->out_pol_inv;

	new_value = value & bit_mask;
	new_value ^= drv_data->out_pol_inv;
	new_value &= bit_mask;

	port->all &= ~bit_mask;
	port->all \|= new_value;

	break;
	default:
	ret = -ENOTSUP;
	goto done;
	}

	ret = _write_port_regs(dev, REG_OUTPUT_PORT0, port);

	done:
	return ret;
	}

	/**
	* @brief Read the pin or port status
	*
	* @param dev Device struct of the PCAL9535A
	* @param access_op Access operation (pin or port)
	* @param pin The pin number
	* @param value Value of input pin(s)
	*
	* @return 0 if successful, failed otherwise
	*/
	static int gpio_pcal9535a_read(struct device *dev, int access_op,
	u32_t pin, u32_t *value)
	{
	union gpio_pcal9535a_port_data buf;
	int ret;

	if (!_has_i2c_master(dev)) {
	return -EINVAL;
	}

	ret = _read_port_regs(dev, REG_INPUT_PORT0, &buf);
	if (ret != 0) {
	goto done;
	}

	switch (access_op) {
	case GPIO_ACCESS_BY_PIN:
	*value = (buf.all >> pin) & 0x01;
	break;
	case GPIO_ACCESS_BY_PORT:
	*value = buf.all;
	break;
	default:
	ret = -ENOTSUP;
	break;
	}

	done:
	return ret;
	}

	static const struct gpio_driver_api gpio_pcal9535a_drv_api_funcs = {
	.config = gpio_pcal9535a_config,
	.write = gpio_pcal9535a_write,
	.read = gpio_pcal9535a_read,
	};

	/**
	* @brief Initialization function of PCAL9535A
	*
	* @param dev Device struct
	* @return 0 if successful, failed otherwise.
	*/
	static int gpio_pcal9535a_init(struct device *dev)
	{
	const struct gpio_pcal9535a_config * const config =
	dev->config->config_info;
	struct gpio_pcal9535a_drv_data * const drv_data =
	(struct gpio_pcal9535a_drv_data * const)dev->driver_data;
	struct device *i2c_master;

	/* Find out the device struct of the I2C master */
	i2c_master = device_get_binding((char *)config->i2c_master_dev_name);
	if (!i2c_master) {
	return -EINVAL;
	}
	drv_data->i2c_master = i2c_master;

	return 0;
	}

	/* Initialization for PCAL9535A_0 */
	#ifdef CONFIG_GPIO_PCAL9535A_0
	static const struct gpio_pcal9535a_config gpio_pcal9535a_0_cfg = {
	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_0_I2C_MASTER_DEV_NAME,
	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_0_I2C_ADDR,
	};

	static struct gpio_pcal9535a_drv_data gpio_pcal9535a_0_drvdata = {
	/* Default for registers according to datasheet */
	.reg_cache.output = { .all = 0xFFFF },
	.reg_cache.pol_inv = { .all = 0x0 },
	.reg_cache.dir = { .all = 0xFFFF },
	.reg_cache.pud_en = { .all = 0x0 },
	.reg_cache.pud_sel = { .all = 0xFFFF },
	};

	/* This has to init after I2C master */
	DEVICE_AND_API_INIT(gpio_pcal9535a_0, CONFIG_GPIO_PCAL9535A_0_DEV_NAME,
	gpio_pcal9535a_init,
	&gpio_pcal9535a_0_drvdata, &gpio_pcal9535a_0_cfg,
	POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
	&gpio_pcal9535a_drv_api_funcs);

	#endif /* CONFIG_GPIO_PCAL9535A_0 */

	/* Initialization for PCAL9535A_1 */
	#ifdef CONFIG_GPIO_PCAL9535A_1
	static const struct gpio_pcal9535a_config gpio_pcal9535a_1_cfg = {
	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_1_I2C_MASTER_DEV_NAME,
	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_1_I2C_ADDR,
	};

	static struct gpio_pcal9535a_drv_data gpio_pcal9535a_1_drvdata = {
	/* Default for registers according to datasheet */
	.reg_cache.output = { .all = 0xFFFF },
	.reg_cache.pol_inv = { .all = 0x0 },
	.reg_cache.dir = { .all = 0xFFFF },
	.reg_cache.pud_en = { .all = 0x0 },
	.reg_cache.pud_sel = { .all = 0xFFFF },
	};

	/* This has to init after I2C master */
	DEVICE_AND_API_INIT(gpio_pcal9535a_1, CONFIG_GPIO_PCAL9535A_1_DEV_NAME,
	gpio_pcal9535a_init,
	&gpio_pcal9535a_1_drvdata, &gpio_pcal9535a_1_cfg,
	POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
	&gpio_pcal9535a_drv_api_funcs);

	#endif /* CONFIG_GPIO_PCAL9535A_1 */

	/* Initialization for PCAL9535A_2 */
	#ifdef CONFIG_GPIO_PCAL9535A_2
	static const struct gpio_pcal9535a_config gpio_pcal9535a_2_cfg = {
	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_2_I2C_MASTER_DEV_NAME,
	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_2_I2C_ADDR,
	};

	static struct gpio_pcal9535a_drv_data gpio_pcal9535a_2_drvdata = {
	/* Default for registers according to datasheet */
	.reg_cache.output = { .all = 0xFFFF },
	.reg_cache.pol_inv = { .all = 0x0 },
	.reg_cache.dir = { .all = 0xFFFF },
	.reg_cache.pud_en = { .all = 0x0 },
	.reg_cache.pud_sel = { .all = 0xFFFF },
	};

	/* This has to init after I2C master */
	DEVICE_AND_API_INIT(gpio_pcal9535a_2, CONFIG_GPIO_PCAL9535A_2_DEV_NAME,
	gpio_pcal9535a_init,
	&gpio_pcal9535a_2_drvdata, &gpio_pcal9535a_2_cfg,
	POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
	&gpio_pcal9535a_drv_api_funcs);

	#endif /* CONFIG_GPIO_PCAL9535A_2 */

	/* Initialization for PCAL9535A_3 */
	#ifdef CONFIG_GPIO_PCAL9535A_3
	static const struct gpio_pcal9535a_config gpio_pcal9535a_3_cfg = {
	.i2c_master_dev_name = CONFIG_GPIO_PCAL9535A_3_I2C_MASTER_DEV_NAME,
	.i2c_slave_addr = CONFIG_GPIO_PCAL9535A_3_I2C_ADDR,
	};

	static struct gpio_pcal9535a_drv_data gpio_pcal9535a_3_drvdata = {
	/* Default for registers according to datasheet */
	.reg_cache.output = { .all = 0xFFFF },
	.reg_cache.pol_inv = { .all = 0x0 },
	.reg_cache.dir = { .all = 0xFFFF },
	.reg_cache.pud_en = { .all = 0x0 },
	.reg_cache.pud_sel = { .all = 0xFFFF },
	};

	/* This has to init after I2C master */
	DEVICE_AND_API_INIT(gpio_pcal9535a_3, CONFIG_GPIO_PCAL9535A_3_DEV_NAME,
	gpio_pcal9535a_init,
	&gpio_pcal9535a_3_drvdata, &gpio_pcal9535a_3_cfg,
	POST_KERNEL, CONFIG_GPIO_PCAL9535A_INIT_PRIORITY,
	&gpio_pcal9535a_drv_api_funcs);

	#endif /* CONFIG_GPIO_PCAL9535A_3 */