text: // SPDX-License-Identifier: GPL-2.0
  /*
   * SAMA5D2 PIOBU GPIO controller
   *
   * Copyright (C) 2018 Microchip Technology Inc. and its subsidiaries
   *
   * Author: Andrei Stefanescu <andrei.stefanescu@microchip.com>
   *
   */
  #include <linux/bits.h>
  #include <linux/gpio/driver.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/mfd/syscon.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/regmap.h>
  
  #define PIOBU_NUM 8
  #define PIOBU_REG_SIZE 4
  
  /*
   * backup mode protection register for tamper detection
   * normal mode protection register for tamper detection
   * wakeup signal generation
   */
  #define PIOBU_BMPR 0x7C
  #define PIOBU_NMPR 0x80
  #define PIOBU_WKPR 0x90
  
  #define PIOBU_BASE 0x18 /* PIOBU offset from SECUMOD base register address. */
  
  #define PIOBU_DET_OFFSET 16
  
  /* In the datasheet this bit is called OUTPUT */
  #define PIOBU_DIRECTION BIT(8)
  #define PIOBU_OUT BIT(8)
  #define PIOBU_IN 0
  
  #define PIOBU_SOD BIT(9)
  #define PIOBU_PDS BIT(10)
  
  #define PIOBU_HIGH BIT(9)
  #define PIOBU_LOW 0
  
  struct sama5d2_piobu {
  	struct gpio_chip chip;
  	struct regmap *regmap;
  };
  
  /*
   * sama5d2_piobu_setup_pin() - prepares a pin for set_direction call
   *
   * Do not consider pin for tamper detection (normal and backup modes)
   * Do not consider pin as tamper wakeup interrupt source
   */
  static int sama5d2_piobu_setup_pin(struct gpio_chip *chip, unsigned int pin)
  {
  	int ret;
  	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
  						   chip);
  	unsigned int mask = BIT(PIOBU_DET_OFFSET + pin);
  
  	ret = regmap_update_bits(piobu->regmap, PIOBU_BMPR, mask, 0);
  	if (ret)
  		return ret;
  
  	ret = regmap_update_bits(piobu->regmap, PIOBU_NMPR, mask, 0);
  	if (ret)
  		return ret;
  
  	return regmap_update_bits(piobu->regmap, PIOBU_WKPR, mask, 0);
  }
  
  /*
   * sama5d2_piobu_write_value() - writes value & mask at the pin's PIOBU register
   */
  static int sama5d2_piobu_write_value(struct gpio_chip *chip, unsigned int pin,
  				     unsigned int mask, unsigned int value)
  {
  	int reg;
  	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
  						   chip);
  
  	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;
  
  	return regmap_update_bits(piobu->regmap, reg, mask, value);
  }
  
  /*
   * sama5d2_piobu_read_value() - read the value with masking from the pin's PIOBU
   *			      register
   */
  static int sama5d2_piobu_read_value(struct gpio_chip *chip, unsigned int pin,
  				    unsigned int mask)
  {
  	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
  						   chip);
  	unsigned int val, reg;
  	int ret;
  
  	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;
  	ret = regmap_read(piobu->regmap, reg, &val);
  	if (ret < 0)
  		return ret;
  
  	return val & mask;
  }
  
  /*
   * sama5d2_piobu_get_direction() - gpiochip get_direction
   */
  static int sama5d2_piobu_get_direction(struct gpio_chip *chip,
  				       unsigned int pin)
  {
  	int ret = sama5d2_piobu_read_value(chip, pin, PIOBU_DIRECTION);
  
  	if (ret < 0)
  		return ret;
  
  	return (ret == PIOBU_IN) ? GPIO_LINE_DIRECTION_IN :
  				   GPIO_LINE_DIRECTION_OUT;
  }
  
  /*
   * sama5d2_piobu_direction_input() - gpiochip direction_input
   */
  static int sama5d2_piobu_direction_input(struct gpio_chip *chip,
  					 unsigned int pin)
  {
  	return sama5d2_piobu_write_value(chip, pin, PIOBU_DIRECTION, PIOBU_IN);
  }
  
  /*
   * sama5d2_piobu_direction_output() - gpiochip direction_output
   */
  static int sama5d2_piobu_direction_output(struct gpio_chip *chip,
  					  unsigned int pin, int value)
  {
  	unsigned int val = PIOBU_OUT;
  
  	if (value)
  		val |= PIOBU_HIGH;
  
  	return sama5d2_piobu_write_value(chip, pin, PIOBU_DIRECTION | PIOBU_SOD,
  					 val);
  }
  
  /*
   * sama5d2_piobu_get() - gpiochip get
   */
  static int sama5d2_piobu_get(struct gpio_chip *chip, unsigned int pin)
  {
  	/* if pin is input, read value from PDS else read from SOD */
  	int ret = sama5d2_piobu_get_direction(chip, pin);
  
  	if (ret == GPIO_LINE_DIRECTION_IN)
  		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_PDS);
  	else if (ret == GPIO_LINE_DIRECTION_OUT)
  		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_SOD);
  
  	if (ret < 0)
  		return ret;
  
  	return !!ret;
  }
  
  /*
   * sama5d2_piobu_set() - gpiochip set
   */
  static void sama5d2_piobu_set(struct gpio_chip *chip, unsigned int pin,
  			      int value)
  {
  	if (!value)
  		value = PIOBU_LOW;
  	else
  		value = PIOBU_HIGH;
  
  	sama5d2_piobu_write_value(chip, pin, PIOBU_SOD, value);
  }
  
  static int sama5d2_piobu_probe(struct platform_device *pdev)
  {
  	struct sama5d2_piobu *piobu;
  	int ret, i;
  
  	piobu = devm_kzalloc(&pdev->dev, sizeof(*piobu), GFP_KERNEL);
  	if (!piobu)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, piobu);
  	piobu->chip.label = pdev->name;
  	piobu->chip.parent = &pdev->dev;
  	piobu->chip.of_node = pdev->dev.of_node;
  	piobu->chip.owner = THIS_MODULE,
  	piobu->chip.get_direction = sama5d2_piobu_get_direction,
  	piobu->chip.direction_input = sama5d2_piobu_direction_input,
  	piobu->chip.direction_output = sama5d2_piobu_direction_output,
  	piobu->chip.get = sama5d2_piobu_get,
  	piobu->chip.set = sama5d2_piobu_set,
  	piobu->chip.base = -1,
  	piobu->chip.ngpio = PIOBU_NUM,
  	piobu->chip.can_sleep = 0,
  
  	piobu->regmap = syscon_node_to_regmap(pdev->dev.of_node);
  	if (IS_ERR(piobu->regmap)) {
  		dev_err(&pdev->dev, "Failed to get syscon regmap %ld\n",
  			PTR_ERR(piobu->regmap));
  		return PTR_ERR(piobu->regmap);
  	}
  
  	ret = devm_gpiochip_add_data(&pdev->dev, &piobu->chip, piobu);
  	if (ret) {
  		dev_err(&pdev->dev, "Failed to add gpiochip %d\n", ret);
  		return ret;
  	}
  
  	for (i = 0; i < PIOBU_NUM; ++i) {
  		ret = sama5d2_piobu_setup_pin(&piobu->chip, i);
  		if (ret) {
  			dev_err(&pdev->dev, "Failed to setup pin: %d %d\n",
  				i, ret);
  			return ret;
  		}
  	}
  
  	return 0;
  }
  
  static const struct of_device_id sama5d2_piobu_ids[] = {
  	{ .compatible = "atmel,sama5d2-secumod" },
  	{},
  };
  MODULE_DEVICE_TABLE(of, sama5d2_piobu_ids);
  
  static struct platform_driver sama5d2_piobu_driver = {
  	.driver = {
  		.name		= "sama5d2-piobu",
  		.of_match_table	= of_match_ptr(sama5d2_piobu_ids)
  	},
  	.probe = sama5d2_piobu_probe,
  };
  
  module_platform_driver(sama5d2_piobu_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("SAMA5D2 PIOBU controller driver");
  MODULE_AUTHOR("Andrei Stefanescu <andrei.stefanescu@microchip.com>");
  