/*
   * Intel Whiskey Cove PMIC GPIO Driver
   *
   * This driver is written based on gpio-crystalcove.c
   *
   * Copyright (C) 2016 Intel Corporation. All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version
   * 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/bitops.h>

  #include <linux/module.h>

  #include <linux/interrupt.h>
  #include <linux/gpio/driver.h>
  #include <linux/mfd/intel_soc_pmic.h>
  #include <linux/platform_device.h>
  #include <linux/regmap.h>
  #include <linux/seq_file.h>
  
  /*
   * Whiskey Cove PMIC has 13 physical GPIO pins divided into 3 banks:
   * Bank 0: Pin 0 - 6
   * Bank 1: Pin 7 - 10
   * Bank 2: Pin 11 -12
   * Each pin has one output control register and one input control register.
   */
  #define BANK0_NR_PINS		7
  #define BANK1_NR_PINS		4
  #define BANK2_NR_PINS		2
  #define WCOVE_GPIO_NUM		(BANK0_NR_PINS + BANK1_NR_PINS + BANK2_NR_PINS)
  #define WCOVE_VGPIO_NUM		94
  /* GPIO output control registers (one per pin): 0x4e44 - 0x4e50 */
  #define GPIO_OUT_CTRL_BASE	0x4e44
  /* GPIO input control registers (one per pin): 0x4e51 - 0x4e5d */
  #define GPIO_IN_CTRL_BASE	0x4e51
  
  /*
   * GPIO interrupts are organized in two groups:
   * Group 0: Bank 0 pins (Pin 0 - 6)
   * Group 1: Bank 1 and Bank 2 pins (Pin 7 - 12)
   * Each group has two registers (one bit per pin): status and mask.
   */
  #define GROUP0_NR_IRQS		7
  #define GROUP1_NR_IRQS		6
  #define IRQ_MASK_BASE		0x4e19
  #define IRQ_STATUS_BASE		0x4e0b

  #define GPIO_IRQ0_MASK		GENMASK(6, 0)
  #define GPIO_IRQ1_MASK		GENMASK(5, 0)

  #define UPDATE_IRQ_TYPE		BIT(0)
  #define UPDATE_IRQ_MASK		BIT(1)
  
  #define CTLI_INTCNT_DIS		(0 << 1)
  #define CTLI_INTCNT_NE		(1 << 1)
  #define CTLI_INTCNT_PE		(2 << 1)
  #define CTLI_INTCNT_BE		(3 << 1)
  
  #define CTLO_DIR_IN		(0 << 5)
  #define CTLO_DIR_OUT		(1 << 5)
  
  #define CTLO_DRV_MASK		(1 << 4)
  #define CTLO_DRV_OD		(0 << 4)
  #define CTLO_DRV_CMOS		(1 << 4)
  
  #define CTLO_DRV_REN		(1 << 3)
  
  #define CTLO_RVAL_2KDOWN	(0 << 1)
  #define CTLO_RVAL_2KUP		(1 << 1)
  #define CTLO_RVAL_50KDOWN	(2 << 1)
  #define CTLO_RVAL_50KUP		(3 << 1)
  
  #define CTLO_INPUT_SET	(CTLO_DRV_CMOS | CTLO_DRV_REN | CTLO_RVAL_2KUP)
  #define CTLO_OUTPUT_SET	(CTLO_DIR_OUT | CTLO_INPUT_SET)
  
  enum ctrl_register {
  	CTRL_IN,
  	CTRL_OUT,
  };
  
  /*
   * struct wcove_gpio - Whiskey Cove GPIO controller
   * @buslock: for bus lock/sync and unlock.
   * @chip: the abstract gpio_chip structure.
   * @dev: the gpio device
   * @regmap: the regmap from the parent device.
   * @regmap_irq_chip: the regmap of the gpio irq chip.
   * @update: pending IRQ setting update, to be written to the chip upon unlock.
   * @intcnt: the Interrupt Detect value to be written.
   * @set_irq_mask: true if the IRQ mask needs to be set, false to clear.
   */
  struct wcove_gpio {
  	struct mutex buslock;
  	struct gpio_chip chip;
  	struct device *dev;
  	struct regmap *regmap;
  	struct regmap_irq_chip_data *regmap_irq_chip;
  	int update;
  	int intcnt;
  	bool set_irq_mask;
  };
  
  static inline unsigned int to_reg(int gpio, enum ctrl_register reg_type)
  {
  	unsigned int reg;

  	if (gpio >= WCOVE_GPIO_NUM)
  		return -EOPNOTSUPP;

  
  	if (reg_type == CTRL_IN)

  		reg = GPIO_IN_CTRL_BASE + gpio;

  	else

  		reg = GPIO_OUT_CTRL_BASE + gpio;

  
  	return reg;
  }
  
  static void wcove_update_irq_mask(struct wcove_gpio *wg, int gpio)
  {
  	unsigned int reg, mask;
  
  	if (gpio < GROUP0_NR_IRQS) {
  		reg = IRQ_MASK_BASE;
  		mask = BIT(gpio % GROUP0_NR_IRQS);
  	} else {
  		reg = IRQ_MASK_BASE + 1;
  		mask = BIT((gpio - GROUP0_NR_IRQS) % GROUP1_NR_IRQS);
  	}
  
  	if (wg->set_irq_mask)
  		regmap_update_bits(wg->regmap, reg, mask, mask);
  	else
  		regmap_update_bits(wg->regmap, reg, mask, 0);
  }
  
  static void wcove_update_irq_ctrl(struct wcove_gpio *wg, int gpio)
  {

  	int reg = to_reg(gpio, CTRL_IN);
  
  	if (reg < 0)
  		return;

  
  	regmap_update_bits(wg->regmap, reg, CTLI_INTCNT_BE, wg->intcnt);
  }
  
  static int wcove_gpio_dir_in(struct gpio_chip *chip, unsigned int gpio)
  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	int reg = to_reg(gpio, CTRL_OUT);
  
  	if (reg < 0)
  		return 0;

  	return regmap_write(wg->regmap, reg, CTLO_INPUT_SET);

  }
  
  static int wcove_gpio_dir_out(struct gpio_chip *chip, unsigned int gpio,
  				    int value)
  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	int reg = to_reg(gpio, CTRL_OUT);

  	if (reg < 0)
  		return 0;
  
  	return regmap_write(wg->regmap, reg, CTLO_OUTPUT_SET | value);

  }

  static int wcove_gpio_get_direction(struct gpio_chip *chip, unsigned int gpio)
  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);
  	unsigned int val;

  	int ret, reg = to_reg(gpio, CTRL_OUT);
  
  	if (reg < 0)
  		return 0;

  	ret = regmap_read(wg->regmap, reg, &val);

  	if (ret)
  		return ret;
  
  	return !(val & CTLO_DIR_OUT);
  }

  static int wcove_gpio_get(struct gpio_chip *chip, unsigned int gpio)
  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);
  	unsigned int val;

  	int ret, reg = to_reg(gpio, CTRL_IN);
  
  	if (reg < 0)
  		return 0;

  	ret = regmap_read(wg->regmap, reg, &val);

  	if (ret)
  		return ret;
  
  	return val & 0x1;
  }
  
  static void wcove_gpio_set(struct gpio_chip *chip,
  				 unsigned int gpio, int value)
  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	int reg = to_reg(gpio, CTRL_OUT);
  
  	if (reg < 0)
  		return;

  
  	if (value)

  		regmap_update_bits(wg->regmap, reg, 1, 1);

  	else

  		regmap_update_bits(wg->regmap, reg, 1, 0);

  }

  static int wcove_gpio_set_config(struct gpio_chip *chip, unsigned int gpio,
  				 unsigned long config)

  {
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	int reg = to_reg(gpio, CTRL_OUT);
  
  	if (reg < 0)
  		return 0;

  	switch (pinconf_to_config_param(config)) {
  	case PIN_CONFIG_DRIVE_OPEN_DRAIN:

  		return regmap_update_bits(wg->regmap, reg, CTLO_DRV_MASK,
  					  CTLO_DRV_OD);

  	case PIN_CONFIG_DRIVE_PUSH_PULL:

  		return regmap_update_bits(wg->regmap, reg, CTLO_DRV_MASK,
  					  CTLO_DRV_CMOS);

  	default:
  		break;
  	}
  
  	return -ENOTSUPP;
  }
  
  static int wcove_irq_type(struct irq_data *data, unsigned int type)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	if (data->hwirq >= WCOVE_GPIO_NUM)
  		return 0;

  	switch (type) {
  	case IRQ_TYPE_NONE:
  		wg->intcnt = CTLI_INTCNT_DIS;
  		break;
  	case IRQ_TYPE_EDGE_BOTH:
  		wg->intcnt = CTLI_INTCNT_BE;
  		break;
  	case IRQ_TYPE_EDGE_RISING:
  		wg->intcnt = CTLI_INTCNT_PE;
  		break;
  	case IRQ_TYPE_EDGE_FALLING:
  		wg->intcnt = CTLI_INTCNT_NE;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	wg->update |= UPDATE_IRQ_TYPE;
  
  	return 0;
  }
  
  static void wcove_bus_lock(struct irq_data *data)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  	struct wcove_gpio *wg = gpiochip_get_data(chip);
  
  	mutex_lock(&wg->buslock);
  }
  
  static void wcove_bus_sync_unlock(struct irq_data *data)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  	struct wcove_gpio *wg = gpiochip_get_data(chip);
  	int gpio = data->hwirq;
  
  	if (wg->update & UPDATE_IRQ_TYPE)
  		wcove_update_irq_ctrl(wg, gpio);
  	if (wg->update & UPDATE_IRQ_MASK)
  		wcove_update_irq_mask(wg, gpio);
  	wg->update = 0;
  
  	mutex_unlock(&wg->buslock);
  }
  
  static void wcove_irq_unmask(struct irq_data *data)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	if (data->hwirq >= WCOVE_GPIO_NUM)
  		return;

  	wg->set_irq_mask = false;
  	wg->update |= UPDATE_IRQ_MASK;
  }
  
  static void wcove_irq_mask(struct irq_data *data)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  	struct wcove_gpio *wg = gpiochip_get_data(chip);

  	if (data->hwirq >= WCOVE_GPIO_NUM)
  		return;

  	wg->set_irq_mask = true;
  	wg->update |= UPDATE_IRQ_MASK;
  }
  
  static struct irq_chip wcove_irqchip = {
  	.name			= "Whiskey Cove",
  	.irq_mask		= wcove_irq_mask,
  	.irq_unmask		= wcove_irq_unmask,
  	.irq_set_type		= wcove_irq_type,
  	.irq_bus_lock		= wcove_bus_lock,
  	.irq_bus_sync_unlock	= wcove_bus_sync_unlock,
  };
  
  static irqreturn_t wcove_gpio_irq_handler(int irq, void *data)
  {
  	struct wcove_gpio *wg = (struct wcove_gpio *)data;
  	unsigned int pending, virq, gpio, mask, offset;
  	u8 p[2];
  
  	if (regmap_bulk_read(wg->regmap, IRQ_STATUS_BASE, p, 2)) {
  		dev_err(wg->dev, "Failed to read irq status register
  ");
  		return IRQ_NONE;
  	}

  	pending = (p[0] & GPIO_IRQ0_MASK) | ((p[1] & GPIO_IRQ1_MASK) << 7);

  	if (!pending)
  		return IRQ_NONE;
  
  	/* Iterate until no interrupt is pending */
  	while (pending) {
  		/* One iteration is for all pending bits */
  		for_each_set_bit(gpio, (const unsigned long *)&pending,

  						 WCOVE_GPIO_NUM) {

  			offset = (gpio > GROUP0_NR_IRQS) ? 1 : 0;
  			mask = (offset == 1) ? BIT(gpio - GROUP0_NR_IRQS) :
  								BIT(gpio);

  			virq = irq_find_mapping(wg->chip.irq.domain, gpio);

  			handle_nested_irq(virq);
  			regmap_update_bits(wg->regmap, IRQ_STATUS_BASE + offset,
  								mask, mask);
  		}
  
  		/* Next iteration */
  		if (regmap_bulk_read(wg->regmap, IRQ_STATUS_BASE, p, 2)) {
  			dev_err(wg->dev, "Failed to read irq status
  ");
  			break;
  		}

  		pending = (p[0] & GPIO_IRQ0_MASK) | ((p[1] & GPIO_IRQ1_MASK) << 7);

  	}
  
  	return IRQ_HANDLED;
  }
  
  static void wcove_gpio_dbg_show(struct seq_file *s,
  				      struct gpio_chip *chip)
  {
  	unsigned int ctlo, ctli, irq_mask, irq_status;
  	struct wcove_gpio *wg = gpiochip_get_data(chip);
  	int gpio, offset, group, ret = 0;
  
  	for (gpio = 0; gpio < WCOVE_GPIO_NUM; gpio++) {
  		group = gpio < GROUP0_NR_IRQS ? 0 : 1;
  		ret += regmap_read(wg->regmap, to_reg(gpio, CTRL_OUT), &ctlo);
  		ret += regmap_read(wg->regmap, to_reg(gpio, CTRL_IN), &ctli);
  		ret += regmap_read(wg->regmap, IRQ_MASK_BASE + group,
  							&irq_mask);
  		ret += regmap_read(wg->regmap, IRQ_STATUS_BASE + group,
  							&irq_status);
  		if (ret) {
  			pr_err("Failed to read registers: ctrl out/in or irq status/mask
  ");
  			break;
  		}
  
  		offset = gpio % 8;
  		seq_printf(s, " gpio-%-2d %s %s %s %s ctlo=%2x,%s %s
  ",
  			   gpio, ctlo & CTLO_DIR_OUT ? "out" : "in ",
  			   ctli & 0x1 ? "hi" : "lo",
  			   ctli & CTLI_INTCNT_NE ? "fall" : "    ",
  			   ctli & CTLI_INTCNT_PE ? "rise" : "    ",
  			   ctlo,
  			   irq_mask & BIT(offset) ? "mask  " : "unmask",
  			   irq_status & BIT(offset) ? "pending" : "       ");
  	}
  }
  
  static int wcove_gpio_probe(struct platform_device *pdev)
  {
  	struct intel_soc_pmic *pmic;
  	struct wcove_gpio *wg;
  	int virq, ret, irq;
  	struct device *dev;
  
  	/*
  	 * This gpio platform device is created by a mfd device (see
  	 * drivers/mfd/intel_soc_pmic_bxtwc.c for details). Information
  	 * shared by all sub-devices created by the mfd device, the regmap
  	 * pointer for instance, is stored as driver data of the mfd device
  	 * driver.
  	 */
  	pmic = dev_get_drvdata(pdev->dev.parent);
  	if (!pmic)
  		return -ENODEV;
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		return irq;
  
  	dev = &pdev->dev;
  
  	wg = devm_kzalloc(dev, sizeof(*wg), GFP_KERNEL);
  	if (!wg)
  		return -ENOMEM;

  	wg->regmap_irq_chip = pmic->irq_chip_data;

  
  	platform_set_drvdata(pdev, wg);
  
  	mutex_init(&wg->buslock);
  	wg->chip.label = KBUILD_MODNAME;
  	wg->chip.direction_input = wcove_gpio_dir_in;
  	wg->chip.direction_output = wcove_gpio_dir_out;

  	wg->chip.get_direction = wcove_gpio_get_direction;

  	wg->chip.get = wcove_gpio_get;
  	wg->chip.set = wcove_gpio_set;

  	wg->chip.set_config = wcove_gpio_set_config,

  	wg->chip.base = -1;
  	wg->chip.ngpio = WCOVE_VGPIO_NUM;
  	wg->chip.can_sleep = true;
  	wg->chip.parent = pdev->dev.parent;
  	wg->chip.dbg_show = wcove_gpio_dbg_show;
  	wg->dev = dev;
  	wg->regmap = pmic->regmap;
  
  	ret = devm_gpiochip_add_data(dev, &wg->chip, wg);
  	if (ret) {
  		dev_err(dev, "Failed to add gpiochip: %d
  ", ret);
  		return ret;
  	}

  	ret = gpiochip_irqchip_add_nested(&wg->chip, &wcove_irqchip, 0,
  					  handle_simple_irq, IRQ_TYPE_NONE);

  	if (ret) {
  		dev_err(dev, "Failed to add irqchip: %d
  ", ret);
  		return ret;
  	}
  
  	virq = regmap_irq_get_virq(wg->regmap_irq_chip, irq);
  	if (virq < 0) {
  		dev_err(dev, "Failed to get virq by irq %d
  ", irq);
  		return virq;
  	}
  
  	ret = devm_request_threaded_irq(dev, virq, NULL,
  		wcove_gpio_irq_handler, IRQF_ONESHOT, pdev->name, wg);
  	if (ret) {
  		dev_err(dev, "Failed to request irq %d
  ", virq);
  		return ret;
  	}

  	gpiochip_set_nested_irqchip(&wg->chip, &wcove_irqchip, virq);

  	/* Enable GPIO0 interrupts */
  	ret = regmap_update_bits(wg->regmap, IRQ_MASK_BASE, GPIO_IRQ0_MASK,
  				 0x00);
  	if (ret)
  		return ret;
  
  	/* Enable GPIO1 interrupts */
  	ret = regmap_update_bits(wg->regmap, IRQ_MASK_BASE + 1, GPIO_IRQ1_MASK,
  				 0x00);
  	if (ret)
  		return ret;

  	return 0;
  }
  
  /*
   * Whiskey Cove PMIC itself is a analog device(but with digital control
   * interface) providing power management support for other devices in
   * the accompanied SoC, so we have no .pm for Whiskey Cove GPIO driver.
   */
  static struct platform_driver wcove_gpio_driver = {
  	.driver = {
  		.name = "bxt_wcove_gpio",
  	},
  	.probe = wcove_gpio_probe,
  };
  
  module_platform_driver(wcove_gpio_driver);
  
  MODULE_AUTHOR("Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>");
  MODULE_AUTHOR("Bin Gao <bin.gao@intel.com>");
  MODULE_DESCRIPTION("Intel Whiskey Cove GPIO Driver");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("platform:bxt_wcove_gpio");