drivers/gpio/gpio-dln2.c - kernel/msm-4.19 - Gitiles

 /*
  * Driver for the Diolan DLN-2 USB-GPIO adapter
  *
  * Copyright (c) 2014 Intel Corporation
  *
  * 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, version 2.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/irqdomain.h>
 #include <linux/irq.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/gpio.h>
 #include <linux/gpio/driver.h>
 #include <linux/platform_device.h>
 #include <linux/mfd/dln2.h>

 #define DLN2_GPIO_ID			0x01

 #define DLN2_GPIO_GET_PIN_COUNT		DLN2_CMD(0x01, DLN2_GPIO_ID)
 #define DLN2_GPIO_SET_DEBOUNCE		DLN2_CMD(0x04, DLN2_GPIO_ID)
 #define DLN2_GPIO_GET_DEBOUNCE		DLN2_CMD(0x05, DLN2_GPIO_ID)
 #define DLN2_GPIO_PORT_GET_VAL		DLN2_CMD(0x06, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_GET_VAL		DLN2_CMD(0x0B, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_SET_OUT_VAL	DLN2_CMD(0x0C, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_GET_OUT_VAL	DLN2_CMD(0x0D, DLN2_GPIO_ID)
 #define DLN2_GPIO_CONDITION_MET_EV	DLN2_CMD(0x0F, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_ENABLE		DLN2_CMD(0x10, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_DISABLE		DLN2_CMD(0x11, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_SET_DIRECTION	DLN2_CMD(0x13, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_GET_DIRECTION	DLN2_CMD(0x14, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_SET_EVENT_CFG	DLN2_CMD(0x1E, DLN2_GPIO_ID)
 #define DLN2_GPIO_PIN_GET_EVENT_CFG	DLN2_CMD(0x1F, DLN2_GPIO_ID)

 #define DLN2_GPIO_EVENT_NONE		0
 #define DLN2_GPIO_EVENT_CHANGE		1
 #define DLN2_GPIO_EVENT_LVL_HIGH	2
 #define DLN2_GPIO_EVENT_LVL_LOW		3
 #define DLN2_GPIO_EVENT_CHANGE_RISING	0x11
 #define DLN2_GPIO_EVENT_CHANGE_FALLING  0x21
 #define DLN2_GPIO_EVENT_MASK		0x0F

 #define DLN2_GPIO_MAX_PINS 32

 struct dln2_gpio {
 	struct platform_device *pdev;
 	struct gpio_chip gpio;

 	/*
 	 * Cache pin direction to save us one transfer, since the hardware has
 	 * separate commands to read the in and out values.
 	 */
 	DECLARE_BITMAP(output_enabled, DLN2_GPIO_MAX_PINS);

 	/* active IRQs - not synced to hardware */
 	DECLARE_BITMAP(unmasked_irqs, DLN2_GPIO_MAX_PINS);
 	/* active IRQS - synced to hardware */
 	DECLARE_BITMAP(enabled_irqs, DLN2_GPIO_MAX_PINS);
 	int irq_type[DLN2_GPIO_MAX_PINS];
 	struct mutex irq_lock;
 };

 struct dln2_gpio_pin {
 	__le16 pin;
 };

 struct dln2_gpio_pin_val {
 	__le16 pin __packed;
 	u8 value;
 };

 static int dln2_gpio_get_pin_count(struct platform_device *pdev)
 {
 	int ret;
 	__le16 count;
 	int len = sizeof(count);

 	ret = dln2_transfer_rx(pdev, DLN2_GPIO_GET_PIN_COUNT, &count, &len);
 	if (ret < 0)
 		return ret;
 	if (len < sizeof(count))
 		return -EPROTO;

 	return le16_to_cpu(count);
 }

 static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
 {
 	struct dln2_gpio_pin req = {
 		.pin = cpu_to_le16(pin),
 	};

 	return dln2_transfer_tx(dln2->pdev, cmd, &req, sizeof(req));
 }

 static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
 {
 	int ret;
 	struct dln2_gpio_pin req = {
 		.pin = cpu_to_le16(pin),
 	};
 	struct dln2_gpio_pin_val rsp;
 	int len = sizeof(rsp);

 	ret = dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), &rsp, &len);
 	if (ret < 0)
 		return ret;
 	if (len < sizeof(rsp) || req.pin != rsp.pin)
 		return -EPROTO;

 	return rsp.value;
 }

 static int dln2_gpio_pin_get_in_val(struct dln2_gpio *dln2, unsigned int pin)
 {
 	int ret;

 	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_VAL, pin);
 	if (ret < 0)
 		return ret;
 	return !!ret;
 }

 static int dln2_gpio_pin_get_out_val(struct dln2_gpio *dln2, unsigned int pin)
 {
 	int ret;

 	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_OUT_VAL, pin);
 	if (ret < 0)
 		return ret;
 	return !!ret;
 }

 static int dln2_gpio_pin_set_out_val(struct dln2_gpio *dln2,
 				     unsigned int pin, int value)
 {
 	struct dln2_gpio_pin_val req = {
 		.pin = cpu_to_le16(pin),
 		.value = value,
 	};

 	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_OUT_VAL, &req,
 				sizeof(req));
 }

 #define DLN2_GPIO_DIRECTION_IN		0
 #define DLN2_GPIO_DIRECTION_OUT		1

 static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
 	struct dln2_gpio_pin req = {
 		.pin = cpu_to_le16(offset),
 	};
 	struct dln2_gpio_pin_val rsp;
 	int len = sizeof(rsp);
 	int ret;

 	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
 	if (ret < 0)
 		return ret;

 	/* cache the pin direction */
 	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
 			    &req, sizeof(req), &rsp, &len);
 	if (ret < 0)
 		return ret;
 	if (len < sizeof(rsp) || req.pin != rsp.pin) {
 		ret = -EPROTO;
 		goto out_disable;
 	}

 	switch (rsp.value) {
 	case DLN2_GPIO_DIRECTION_IN:
 		clear_bit(offset, dln2->output_enabled);
 		return 0;
 	case DLN2_GPIO_DIRECTION_OUT:
 		set_bit(offset, dln2->output_enabled);
 		return 0;
 	default:
 		ret = -EPROTO;
 		goto out_disable;
 	}

 out_disable:
 	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
 	return ret;
 }

 static void dln2_gpio_free(struct gpio_chip *chip, unsigned offset)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

 	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
 }

 static int dln2_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

 	if (test_bit(offset, dln2->output_enabled))
 		return GPIOF_DIR_OUT;

 	return GPIOF_DIR_IN;
 }

 static int dln2_gpio_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
 	int dir;

 	dir = dln2_gpio_get_direction(chip, offset);
 	if (dir < 0)
 		return dir;

 	if (dir == GPIOF_DIR_IN)
 		return dln2_gpio_pin_get_in_val(dln2, offset);

 	return dln2_gpio_pin_get_out_val(dln2, offset);
 }

 static void dln2_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

 	dln2_gpio_pin_set_out_val(dln2, offset, value);
 }

 static int dln2_gpio_set_direction(struct gpio_chip *chip, unsigned offset,
 				   unsigned dir)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
 	struct dln2_gpio_pin_val req = {
 		.pin = cpu_to_le16(offset),
 		.value = dir,
 	};
 	int ret;

 	ret = dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_DIRECTION,
 			       &req, sizeof(req));
 	if (ret < 0)
 		return ret;

 	if (dir == DLN2_GPIO_DIRECTION_OUT)
 		set_bit(offset, dln2->output_enabled);
 	else
 		clear_bit(offset, dln2->output_enabled);

 	return ret;
 }

 static int dln2_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 {
 	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_IN);
 }

 static int dln2_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 				      int value)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
 	int ret;

 	ret = dln2_gpio_pin_set_out_val(dln2, offset, value);
 	if (ret < 0)
 		return ret;

 	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_OUT);
 }

 static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
 				  unsigned debounce)
 {
 	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
 	__le32 duration = cpu_to_le32(debounce);

 	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
 				&duration, sizeof(duration));
 }

 static int dln2_gpio_set_event_cfg(struct dln2_gpio *dln2, unsigned pin,
 				   unsigned type, unsigned period)
 {
 	struct {
 		__le16 pin;
 		u8 type;
 		__le16 period;
 	} __packed req = {
 		.pin = cpu_to_le16(pin),
 		.type = type,
 		.period = cpu_to_le16(period),
 	};

 	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_EVENT_CFG,
 				&req, sizeof(req));
 }

 static void dln2_irq_unmask(struct irq_data *irqd)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
 	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
 	int pin = irqd_to_hwirq(irqd);

 	set_bit(pin, dln2->unmasked_irqs);
 }

 static void dln2_irq_mask(struct irq_data *irqd)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
 	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
 	int pin = irqd_to_hwirq(irqd);

 	clear_bit(pin, dln2->unmasked_irqs);
 }

 static int dln2_irq_set_type(struct irq_data *irqd, unsigned type)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
 	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
 	int pin = irqd_to_hwirq(irqd);

 	switch (type) {
 	case IRQ_TYPE_LEVEL_HIGH:
 		dln2->irq_type[pin] = DLN2_GPIO_EVENT_LVL_HIGH;
 		break;
 	case IRQ_TYPE_LEVEL_LOW:
 		dln2->irq_type[pin] = DLN2_GPIO_EVENT_LVL_LOW;
 		break;
 	case IRQ_TYPE_EDGE_BOTH:
 		dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE;
 		break;
 	case IRQ_TYPE_EDGE_RISING:
 		dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE_RISING;
 		break;
 	case IRQ_TYPE_EDGE_FALLING:
 		dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE_FALLING;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static void dln2_irq_bus_lock(struct irq_data *irqd)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
 	struct dln2_gpio *dln2 = gpiochip_get_data(gc);

 	mutex_lock(&dln2->irq_lock);
 }

 static void dln2_irq_bus_unlock(struct irq_data *irqd)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
 	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
 	int pin = irqd_to_hwirq(irqd);
 	int enabled, unmasked;
 	unsigned type;
 	int ret;

 	enabled = test_bit(pin, dln2->enabled_irqs);
 	unmasked = test_bit(pin, dln2->unmasked_irqs);

 	if (enabled != unmasked) {
 		if (unmasked) {
 			type = dln2->irq_type[pin] & DLN2_GPIO_EVENT_MASK;
 			set_bit(pin, dln2->enabled_irqs);
 		} else {
 			type = DLN2_GPIO_EVENT_NONE;
 			clear_bit(pin, dln2->enabled_irqs);
 		}

 		ret = dln2_gpio_set_event_cfg(dln2, pin, type, 0);
 		if (ret)
 			dev_err(dln2->gpio.parent, "failed to set event\n");
 	}

 	mutex_unlock(&dln2->irq_lock);
 }

 static struct irq_chip dln2_gpio_irqchip = {
 	.name = "dln2-irq",
 	.irq_mask = dln2_irq_mask,
 	.irq_unmask = dln2_irq_unmask,
 	.irq_set_type = dln2_irq_set_type,
 	.irq_bus_lock = dln2_irq_bus_lock,
 	.irq_bus_sync_unlock = dln2_irq_bus_unlock,
 };

 static void dln2_gpio_event(struct platform_device *pdev, u16 echo,
 			    const void *data, int len)
 {
 	int pin, irq;

 	const struct {
 		__le16 count;
 		__u8 type;
 		__le16 pin;
 		__u8 value;
 	} __packed *event = data;
 	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);

 	if (len < sizeof(*event)) {
 		dev_err(dln2->gpio.parent, "short event message\n");
 		return;
 	}

 	pin = le16_to_cpu(event->pin);
 	if (pin >= dln2->gpio.ngpio) {
 		dev_err(dln2->gpio.parent, "out of bounds pin %d\n", pin);
 		return;
 	}

 	irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
 	if (!irq) {
 		dev_err(dln2->gpio.parent, "pin %d not mapped to IRQ\n", pin);
 		return;
 	}

 	switch (dln2->irq_type[pin]) {
 	case DLN2_GPIO_EVENT_CHANGE_RISING:
 		if (event->value)
 			generic_handle_irq(irq);
 		break;
 	case DLN2_GPIO_EVENT_CHANGE_FALLING:
 		if (!event->value)
 			generic_handle_irq(irq);
 		break;
 	default:
 		generic_handle_irq(irq);
 	}
 }

 static int dln2_gpio_probe(struct platform_device *pdev)
 {
 	struct dln2_gpio *dln2;
 	struct device *dev = &pdev->dev;
 	int pins;
 	int ret;

 	pins = dln2_gpio_get_pin_count(pdev);
 	if (pins < 0) {
 		dev_err(dev, "failed to get pin count: %d\n", pins);
 		return pins;
 	}
 	if (pins > DLN2_GPIO_MAX_PINS) {
 		pins = DLN2_GPIO_MAX_PINS;
 		dev_warn(dev, "clamping pins to %d\n", DLN2_GPIO_MAX_PINS);
 	}

 	dln2 = devm_kzalloc(&pdev->dev, sizeof(*dln2), GFP_KERNEL);
 	if (!dln2)
 		return -ENOMEM;

 	mutex_init(&dln2->irq_lock);

 	dln2->pdev = pdev;

 	dln2->gpio.label = "dln2";
 	dln2->gpio.parent = dev;
 	dln2->gpio.owner = THIS_MODULE;
 	dln2->gpio.base = -1;
 	dln2->gpio.ngpio = pins;
 	dln2->gpio.can_sleep = true;
 	dln2->gpio.set = dln2_gpio_set;
 	dln2->gpio.get = dln2_gpio_get;
 	dln2->gpio.request = dln2_gpio_request;
 	dln2->gpio.free = dln2_gpio_free;
 	dln2->gpio.get_direction = dln2_gpio_get_direction;
 	dln2->gpio.direction_input = dln2_gpio_direction_input;
 	dln2->gpio.direction_output = dln2_gpio_direction_output;
 	dln2->gpio.set_debounce = dln2_gpio_set_debounce;

 	platform_set_drvdata(pdev, dln2);

 	ret = devm_gpiochip_add_data(dev, &dln2->gpio, dln2);
 	if (ret < 0) {
 		dev_err(dev, "failed to add gpio chip: %d\n", ret);
 		return ret;
 	}

 	ret = gpiochip_irqchip_add(&dln2->gpio, &dln2_gpio_irqchip, 0,
 				   handle_simple_irq, IRQ_TYPE_NONE);
 	if (ret < 0) {
 		dev_err(dev, "failed to add irq chip: %d\n", ret);
 		return ret;
 	}

 	ret = dln2_register_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV,
 				     dln2_gpio_event);
 	if (ret) {
 		dev_err(dev, "failed to register event cb: %d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static int dln2_gpio_remove(struct platform_device *pdev)
 {
 	dln2_unregister_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV);

 	return 0;
 }

 static struct platform_driver dln2_gpio_driver = {
 	.driver.name	= "dln2-gpio",
 	.probe		= dln2_gpio_probe,
 	.remove		= dln2_gpio_remove,
 };

 module_platform_driver(dln2_gpio_driver);

 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com");
 MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:dln2-gpio");
	/*
	* Driver for the Diolan DLN-2 USB-GPIO adapter
	*
	* Copyright (c) 2014 Intel Corporation
	*
	* 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, version 2.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/types.h>
	#include <linux/irqdomain.h>
	#include <linux/irq.h>
	#include <linux/irqchip/chained_irq.h>
	#include <linux/gpio.h>
	#include <linux/gpio/driver.h>
	#include <linux/platform_device.h>
	#include <linux/mfd/dln2.h>

	#define DLN2_GPIO_ID 0x01

	#define DLN2_GPIO_GET_PIN_COUNT DLN2_CMD(0x01, DLN2_GPIO_ID)
	#define DLN2_GPIO_SET_DEBOUNCE DLN2_CMD(0x04, DLN2_GPIO_ID)
	#define DLN2_GPIO_GET_DEBOUNCE DLN2_CMD(0x05, DLN2_GPIO_ID)
	#define DLN2_GPIO_PORT_GET_VAL DLN2_CMD(0x06, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_GET_VAL DLN2_CMD(0x0B, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_SET_OUT_VAL DLN2_CMD(0x0C, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_GET_OUT_VAL DLN2_CMD(0x0D, DLN2_GPIO_ID)
	#define DLN2_GPIO_CONDITION_MET_EV DLN2_CMD(0x0F, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_ENABLE DLN2_CMD(0x10, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_DISABLE DLN2_CMD(0x11, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_SET_DIRECTION DLN2_CMD(0x13, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_GET_DIRECTION DLN2_CMD(0x14, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_SET_EVENT_CFG DLN2_CMD(0x1E, DLN2_GPIO_ID)
	#define DLN2_GPIO_PIN_GET_EVENT_CFG DLN2_CMD(0x1F, DLN2_GPIO_ID)

	#define DLN2_GPIO_EVENT_NONE 0
	#define DLN2_GPIO_EVENT_CHANGE 1
	#define DLN2_GPIO_EVENT_LVL_HIGH 2
	#define DLN2_GPIO_EVENT_LVL_LOW 3
	#define DLN2_GPIO_EVENT_CHANGE_RISING 0x11
	#define DLN2_GPIO_EVENT_CHANGE_FALLING 0x21
	#define DLN2_GPIO_EVENT_MASK 0x0F

	#define DLN2_GPIO_MAX_PINS 32

	struct dln2_gpio {
	struct platform_device *pdev;
	struct gpio_chip gpio;

	/*
	* Cache pin direction to save us one transfer, since the hardware has
	* separate commands to read the in and out values.
	*/
	DECLARE_BITMAP(output_enabled, DLN2_GPIO_MAX_PINS);

	/* active IRQs - not synced to hardware */
	DECLARE_BITMAP(unmasked_irqs, DLN2_GPIO_MAX_PINS);
	/* active IRQS - synced to hardware */
	DECLARE_BITMAP(enabled_irqs, DLN2_GPIO_MAX_PINS);
	int irq_type[DLN2_GPIO_MAX_PINS];
	struct mutex irq_lock;
	};

	struct dln2_gpio_pin {
	__le16 pin;
	};

	struct dln2_gpio_pin_val {
	__le16 pin __packed;
	u8 value;
	};

	static int dln2_gpio_get_pin_count(struct platform_device *pdev)
	{
	int ret;
	__le16 count;
	int len = sizeof(count);

	ret = dln2_transfer_rx(pdev, DLN2_GPIO_GET_PIN_COUNT, &count, &len);
	if (ret < 0)
	return ret;
	if (len < sizeof(count))
	return -EPROTO;

	return le16_to_cpu(count);
	}

	static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
	{
	struct dln2_gpio_pin req = {
	.pin = cpu_to_le16(pin),
	};

	return dln2_transfer_tx(dln2->pdev, cmd, &req, sizeof(req));
	}

	static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
	{
	int ret;
	struct dln2_gpio_pin req = {
	.pin = cpu_to_le16(pin),
	};
	struct dln2_gpio_pin_val rsp;
	int len = sizeof(rsp);

	ret = dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), &rsp, &len);
	if (ret < 0)
	return ret;
	if (len < sizeof(rsp) \|\| req.pin != rsp.pin)
	return -EPROTO;

	return rsp.value;
	}

	static int dln2_gpio_pin_get_in_val(struct dln2_gpio *dln2, unsigned int pin)
	{
	int ret;

	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_VAL, pin);
	if (ret < 0)
	return ret;
	return !!ret;
	}

	static int dln2_gpio_pin_get_out_val(struct dln2_gpio *dln2, unsigned int pin)
	{
	int ret;

	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_OUT_VAL, pin);
	if (ret < 0)
	return ret;
	return !!ret;
	}

	static int dln2_gpio_pin_set_out_val(struct dln2_gpio *dln2,
	unsigned int pin, int value)
	{
	struct dln2_gpio_pin_val req = {
	.pin = cpu_to_le16(pin),
	.value = value,
	};

	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_OUT_VAL, &req,
	sizeof(req));
	}

	#define DLN2_GPIO_DIRECTION_IN 0
	#define DLN2_GPIO_DIRECTION_OUT 1

	static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
	struct dln2_gpio_pin req = {
	.pin = cpu_to_le16(offset),
	};
	struct dln2_gpio_pin_val rsp;
	int len = sizeof(rsp);
	int ret;

	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
	if (ret < 0)
	return ret;

	/* cache the pin direction */
	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
	&req, sizeof(req), &rsp, &len);
	if (ret < 0)
	return ret;
	if (len < sizeof(rsp) \|\| req.pin != rsp.pin) {
	ret = -EPROTO;
	goto out_disable;
	}

	switch (rsp.value) {
	case DLN2_GPIO_DIRECTION_IN:
	clear_bit(offset, dln2->output_enabled);
	return 0;
	case DLN2_GPIO_DIRECTION_OUT:
	set_bit(offset, dln2->output_enabled);
	return 0;
	default:
	ret = -EPROTO;
	goto out_disable;
	}

	out_disable:
	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
	return ret;
	}

	static void dln2_gpio_free(struct gpio_chip *chip, unsigned offset)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
	}

	static int dln2_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

	if (test_bit(offset, dln2->output_enabled))
	return GPIOF_DIR_OUT;

	return GPIOF_DIR_IN;
	}

	static int dln2_gpio_get(struct gpio_chip *chip, unsigned int offset)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
	int dir;

	dir = dln2_gpio_get_direction(chip, offset);
	if (dir < 0)
	return dir;

	if (dir == GPIOF_DIR_IN)
	return dln2_gpio_pin_get_in_val(dln2, offset);

	return dln2_gpio_pin_get_out_val(dln2, offset);
	}

	static void dln2_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);

	dln2_gpio_pin_set_out_val(dln2, offset, value);
	}

	static int dln2_gpio_set_direction(struct gpio_chip *chip, unsigned offset,
	unsigned dir)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
	struct dln2_gpio_pin_val req = {
	.pin = cpu_to_le16(offset),
	.value = dir,
	};
	int ret;

	ret = dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_DIRECTION,
	&req, sizeof(req));
	if (ret < 0)
	return ret;

	if (dir == DLN2_GPIO_DIRECTION_OUT)
	set_bit(offset, dln2->output_enabled);
	else
	clear_bit(offset, dln2->output_enabled);

	return ret;
	}

	static int dln2_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
	{
	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_IN);
	}

	static int dln2_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
	int value)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
	int ret;

	ret = dln2_gpio_pin_set_out_val(dln2, offset, value);
	if (ret < 0)
	return ret;

	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_OUT);
	}

	static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
	unsigned debounce)
	{
	struct dln2_gpio *dln2 = gpiochip_get_data(chip);
	__le32 duration = cpu_to_le32(debounce);

	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
	&duration, sizeof(duration));
	}

	static int dln2_gpio_set_event_cfg(struct dln2_gpio *dln2, unsigned pin,
	unsigned type, unsigned period)
	{
	struct {
	__le16 pin;
	u8 type;
	__le16 period;
	} __packed req = {
	.pin = cpu_to_le16(pin),
	.type = type,
	.period = cpu_to_le16(period),
	};

	return dln2_transfer_tx(dln2->pdev, DLN2_GPIO_PIN_SET_EVENT_CFG,
	&req, sizeof(req));
	}

	static void dln2_irq_unmask(struct irq_data *irqd)
	{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
	int pin = irqd_to_hwirq(irqd);

	set_bit(pin, dln2->unmasked_irqs);
	}

	static void dln2_irq_mask(struct irq_data *irqd)
	{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
	int pin = irqd_to_hwirq(irqd);

	clear_bit(pin, dln2->unmasked_irqs);
	}

	static int dln2_irq_set_type(struct irq_data *irqd, unsigned type)
	{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
	int pin = irqd_to_hwirq(irqd);

	switch (type) {
	case IRQ_TYPE_LEVEL_HIGH:
	dln2->irq_type[pin] = DLN2_GPIO_EVENT_LVL_HIGH;
	break;
	case IRQ_TYPE_LEVEL_LOW:
	dln2->irq_type[pin] = DLN2_GPIO_EVENT_LVL_LOW;
	break;
	case IRQ_TYPE_EDGE_BOTH:
	dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE;
	break;
	case IRQ_TYPE_EDGE_RISING:
	dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE_RISING;
	break;
	case IRQ_TYPE_EDGE_FALLING:
	dln2->irq_type[pin] = DLN2_GPIO_EVENT_CHANGE_FALLING;
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static void dln2_irq_bus_lock(struct irq_data *irqd)
	{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct dln2_gpio *dln2 = gpiochip_get_data(gc);

	mutex_lock(&dln2->irq_lock);
	}

	static void dln2_irq_bus_unlock(struct irq_data *irqd)
	{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct dln2_gpio *dln2 = gpiochip_get_data(gc);
	int pin = irqd_to_hwirq(irqd);
	int enabled, unmasked;
	unsigned type;
	int ret;

	enabled = test_bit(pin, dln2->enabled_irqs);
	unmasked = test_bit(pin, dln2->unmasked_irqs);

	if (enabled != unmasked) {
	if (unmasked) {
	type = dln2->irq_type[pin] & DLN2_GPIO_EVENT_MASK;
	set_bit(pin, dln2->enabled_irqs);
	} else {
	type = DLN2_GPIO_EVENT_NONE;
	clear_bit(pin, dln2->enabled_irqs);
	}

	ret = dln2_gpio_set_event_cfg(dln2, pin, type, 0);
	if (ret)
	dev_err(dln2->gpio.parent, "failed to set event\n");
	}

	mutex_unlock(&dln2->irq_lock);
	}

	static struct irq_chip dln2_gpio_irqchip = {
	.name = "dln2-irq",
	.irq_mask = dln2_irq_mask,
	.irq_unmask = dln2_irq_unmask,
	.irq_set_type = dln2_irq_set_type,
	.irq_bus_lock = dln2_irq_bus_lock,
	.irq_bus_sync_unlock = dln2_irq_bus_unlock,
	};

	static void dln2_gpio_event(struct platform_device *pdev, u16 echo,
	const void *data, int len)
	{
	int pin, irq;

	const struct {
	__le16 count;
	__u8 type;
	__le16 pin;
	__u8 value;
	} __packed *event = data;
	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);

	if (len < sizeof(*event)) {
	dev_err(dln2->gpio.parent, "short event message\n");
	return;
	}

	pin = le16_to_cpu(event->pin);
	if (pin >= dln2->gpio.ngpio) {
	dev_err(dln2->gpio.parent, "out of bounds pin %d\n", pin);
	return;
	}

	irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
	if (!irq) {
	dev_err(dln2->gpio.parent, "pin %d not mapped to IRQ\n", pin);
	return;
	}

	switch (dln2->irq_type[pin]) {
	case DLN2_GPIO_EVENT_CHANGE_RISING:
	if (event->value)
	generic_handle_irq(irq);
	break;
	case DLN2_GPIO_EVENT_CHANGE_FALLING:
	if (!event->value)
	generic_handle_irq(irq);
	break;
	default:
	generic_handle_irq(irq);
	}
	}

	static int dln2_gpio_probe(struct platform_device *pdev)
	{
	struct dln2_gpio *dln2;
	struct device *dev = &pdev->dev;
	int pins;
	int ret;

	pins = dln2_gpio_get_pin_count(pdev);
	if (pins < 0) {
	dev_err(dev, "failed to get pin count: %d\n", pins);
	return pins;
	}
	if (pins > DLN2_GPIO_MAX_PINS) {
	pins = DLN2_GPIO_MAX_PINS;
	dev_warn(dev, "clamping pins to %d\n", DLN2_GPIO_MAX_PINS);
	}

	dln2 = devm_kzalloc(&pdev->dev, sizeof(*dln2), GFP_KERNEL);
	if (!dln2)
	return -ENOMEM;

	mutex_init(&dln2->irq_lock);

	dln2->pdev = pdev;

	dln2->gpio.label = "dln2";
	dln2->gpio.parent = dev;
	dln2->gpio.owner = THIS_MODULE;
	dln2->gpio.base = -1;
	dln2->gpio.ngpio = pins;
	dln2->gpio.can_sleep = true;
	dln2->gpio.set = dln2_gpio_set;
	dln2->gpio.get = dln2_gpio_get;
	dln2->gpio.request = dln2_gpio_request;
	dln2->gpio.free = dln2_gpio_free;
	dln2->gpio.get_direction = dln2_gpio_get_direction;
	dln2->gpio.direction_input = dln2_gpio_direction_input;
	dln2->gpio.direction_output = dln2_gpio_direction_output;
	dln2->gpio.set_debounce = dln2_gpio_set_debounce;

	platform_set_drvdata(pdev, dln2);

	ret = devm_gpiochip_add_data(dev, &dln2->gpio, dln2);
	if (ret < 0) {
	dev_err(dev, "failed to add gpio chip: %d\n", ret);
	return ret;
	}

	ret = gpiochip_irqchip_add(&dln2->gpio, &dln2_gpio_irqchip, 0,
	handle_simple_irq, IRQ_TYPE_NONE);
	if (ret < 0) {
	dev_err(dev, "failed to add irq chip: %d\n", ret);
	return ret;
	}

	ret = dln2_register_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV,
	dln2_gpio_event);
	if (ret) {
	dev_err(dev, "failed to register event cb: %d\n", ret);
	return ret;
	}

	return 0;
	}

	static int dln2_gpio_remove(struct platform_device *pdev)
	{
	dln2_unregister_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV);

	return 0;
	}

	static struct platform_driver dln2_gpio_driver = {
	.driver.name = "dln2-gpio",
	.probe = dln2_gpio_probe,
	.remove = dln2_gpio_remove,
	};

	module_platform_driver(dln2_gpio_driver);

	MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com");
	MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:dln2-gpio");