/*
   * GPIO controller driver for Intel Lynxpoint PCH chipset>
   * Copyright (c) 2012, Intel Corporation.
   *
   * Author: Mathias Nyman <mathias.nyman@linux.intel.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope 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.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc.,
   * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/types.h>
  #include <linux/bitops.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/gpio.h>
  #include <linux/irqdomain.h>
  #include <linux/slab.h>
  #include <linux/acpi.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
  #include <linux/io.h>
  
  /* LynxPoint chipset has support for 94 gpio pins */
  
  #define LP_NUM_GPIO	94
  
  /* Bitmapped register offsets */
  #define LP_ACPI_OWNED	0x00 /* Bitmap, set by bios, 0: pin reserved for ACPI */
  #define LP_GC		0x7C /* set APIC IRQ to IRQ14 or IRQ15 for all pins */
  #define LP_INT_STAT	0x80
  #define LP_INT_ENABLE	0x90
  
  /* Each pin has two 32 bit config registers, starting at 0x100 */
  #define LP_CONFIG1	0x100
  #define LP_CONFIG2	0x104
  
  /* LP_CONFIG1 reg bits */
  #define OUT_LVL_BIT	BIT(31)
  #define IN_LVL_BIT	BIT(30)
  #define TRIG_SEL_BIT	BIT(4) /* 0: Edge, 1: Level */
  #define INT_INV_BIT	BIT(3) /* Invert interrupt triggering */
  #define DIR_BIT		BIT(2) /* 0: Output, 1: Input */
  #define USE_SEL_BIT	BIT(0) /* 0: Native, 1: GPIO */
  
  /* LP_CONFIG2 reg bits */
  #define GPINDIS_BIT	BIT(2) /* disable input sensing */
  #define GPIWP_BIT	(BIT(0) | BIT(1)) /* weak pull options */
  
  struct lp_gpio {
  	struct gpio_chip	chip;
  	struct irq_domain	*domain;
  	struct platform_device	*pdev;
  	spinlock_t		lock;
  	unsigned long		reg_base;
  };
  
  /*
   * Lynxpoint gpios are controlled through both bitmapped registers and
   * per gpio specific registers. The bitmapped registers are in chunks of
   * 3 x 32bit registers to cover all 94 gpios
   *
   * per gpio specific registers consist of two 32bit registers per gpio
   * (LP_CONFIG1 and LP_CONFIG2), with 94 gpios there's a total of
   * 188 config registes.
   *
   * A simplified view of the register layout look like this:
   *
   * LP_ACPI_OWNED[31:0] gpio ownerships for gpios 0-31  (bitmapped registers)
   * LP_ACPI_OWNED[63:32] gpio ownerships for gpios 32-63
   * LP_ACPI_OWNED[94:64] gpio ownerships for gpios 63-94
   * ...
   * LP_INT_ENABLE[31:0] ...
   * LP_INT_ENABLE[63:31] ...
   * LP_INT_ENABLE[94:64] ...
   * LP0_CONFIG1 (gpio 0) config1 reg for gpio 0 (per gpio registers)
   * LP0_CONFIG2 (gpio 0) config2 reg for gpio 0
   * LP1_CONFIG1 (gpio 1) config1 reg for gpio 1
   * LP1_CONFIG2 (gpio 1) config2 reg for gpio 1
   * LP2_CONFIG1 (gpio 2) ...
   * LP2_CONFIG2 (gpio 2) ...
   * ...
   * LP94_CONFIG1 (gpio 94) ...
   * LP94_CONFIG2 (gpio 94) ...
   */
  
  static unsigned long lp_gpio_reg(struct gpio_chip *chip, unsigned offset,
  				 int reg)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	int reg_offset;
  
  	if (reg == LP_CONFIG1 || reg == LP_CONFIG2)
  		/* per gpio specific config registers */
  		reg_offset = offset * 8;
  	else
  		/* bitmapped registers */
  		reg_offset = (offset / 32) * 4;
  
  	return lg->reg_base + reg + reg_offset;
  }
  
  static int lp_gpio_request(struct gpio_chip *chip, unsigned offset)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	unsigned long reg = lp_gpio_reg(chip, offset, LP_CONFIG1);
  	unsigned long conf2 = lp_gpio_reg(chip, offset, LP_CONFIG2);
  	unsigned long acpi_use = lp_gpio_reg(chip, offset, LP_ACPI_OWNED);
  
  	pm_runtime_get(&lg->pdev->dev); /* should we put if failed */
  
  	/* Fail if BIOS reserved pin for ACPI use */
  	if (!(inl(acpi_use) & BIT(offset % 32))) {
  		dev_err(&lg->pdev->dev, "gpio %d reserved for ACPI
  ", offset);
  		return -EBUSY;
  	}
  	/* Fail if pin is in alternate function mode (not GPIO mode) */
  	if (!(inl(reg) & USE_SEL_BIT))
  		return -ENODEV;
  
  	/* enable input sensing */
  	outl(inl(conf2) & ~GPINDIS_BIT, conf2);
  
  
  	return 0;
  }
  
  static void lp_gpio_free(struct gpio_chip *chip, unsigned offset)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	unsigned long conf2 = lp_gpio_reg(chip, offset, LP_CONFIG2);
  
  	/* disable input sensing */
  	outl(inl(conf2) | GPINDIS_BIT, conf2);
  
  	pm_runtime_put(&lg->pdev->dev);
  }
  
  static int lp_irq_type(struct irq_data *d, unsigned type)
  {
  	struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
  	u32 hwirq = irqd_to_hwirq(d);
  	unsigned long flags;
  	u32 value;
  	unsigned long reg = lp_gpio_reg(&lg->chip, hwirq, LP_CONFIG1);
  
  	if (hwirq >= lg->chip.ngpio)
  		return -EINVAL;
  
  	spin_lock_irqsave(&lg->lock, flags);
  	value = inl(reg);
  
  	/* set both TRIG_SEL and INV bits to 0 for rising edge */
  	if (type & IRQ_TYPE_EDGE_RISING)
  		value &= ~(TRIG_SEL_BIT | INT_INV_BIT);
  
  	/* TRIG_SEL bit 0, INV bit 1 for falling edge */
  	if (type & IRQ_TYPE_EDGE_FALLING)
  		value = (value | INT_INV_BIT) & ~TRIG_SEL_BIT;
  
  	/* TRIG_SEL bit 1, INV bit 0 for level low */
  	if (type & IRQ_TYPE_LEVEL_LOW)
  		value = (value | TRIG_SEL_BIT) & ~INT_INV_BIT;
  
  	/* TRIG_SEL bit 1, INV bit 1 for level high */
  	if (type & IRQ_TYPE_LEVEL_HIGH)
  		value |= TRIG_SEL_BIT | INT_INV_BIT;
  
  	outl(value, reg);
  	spin_unlock_irqrestore(&lg->lock, flags);
  
  	return 0;
  }
  
  static int lp_gpio_get(struct gpio_chip *chip, unsigned offset)
  {
  	unsigned long reg = lp_gpio_reg(chip, offset, LP_CONFIG1);
  	return inl(reg) & IN_LVL_BIT;
  }
  
  static void lp_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	unsigned long reg = lp_gpio_reg(chip, offset, LP_CONFIG1);
  	unsigned long flags;
  
  	spin_lock_irqsave(&lg->lock, flags);
  
  	if (value)
  		outl(inl(reg) | OUT_LVL_BIT, reg);
  	else
  		outl(inl(reg) & ~OUT_LVL_BIT, reg);
  
  	spin_unlock_irqrestore(&lg->lock, flags);
  }
  
  static int lp_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	unsigned long reg = lp_gpio_reg(chip, offset, LP_CONFIG1);
  	unsigned long flags;
  
  	spin_lock_irqsave(&lg->lock, flags);
  	outl(inl(reg) | DIR_BIT, reg);
  	spin_unlock_irqrestore(&lg->lock, flags);
  
  	return 0;
  }
  
  static int lp_gpio_direction_output(struct gpio_chip *chip,
  				      unsigned offset, int value)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	unsigned long reg = lp_gpio_reg(chip, offset, LP_CONFIG1);
  	unsigned long flags;
  
  	lp_gpio_set(chip, offset, value);
  
  	spin_lock_irqsave(&lg->lock, flags);
  	outl(inl(reg) & ~DIR_BIT, reg);
  	spin_unlock_irqrestore(&lg->lock, flags);
  
  	return 0;
  }
  
  static int lp_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
  {
  	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
  	return irq_create_mapping(lg->domain, offset);
  }
  
  static void lp_gpio_irq_handler(unsigned hwirq, struct irq_desc *desc)
  {
  	struct irq_data *data = irq_desc_get_irq_data(desc);
  	struct lp_gpio *lg = irq_data_get_irq_handler_data(data);
  	struct irq_chip *chip = irq_data_get_irq_chip(data);
  	u32 base, pin, mask;
  	unsigned long reg, ena, pending;
  
  	/* check from GPIO controller which pin triggered the interrupt */
  	for (base = 0; base < lg->chip.ngpio; base += 32) {
  		reg = lp_gpio_reg(&lg->chip, base, LP_INT_STAT);
  		ena = lp_gpio_reg(&lg->chip, base, LP_INT_ENABLE);
  
  		while ((pending = (inl(reg) & inl(ena)))) {
  			unsigned irq;
  
  			pin = __ffs(pending);
  			mask = BIT(pin);
  			/* Clear before handling so we don't lose an edge */
  			outl(mask, reg);
  			irq = irq_find_mapping(lg->domain, base + pin);
  			generic_handle_irq(irq);
  		}
  	}
  	chip->irq_eoi(data);
  }
  
  static void lp_irq_unmask(struct irq_data *d)
  {
  }
  
  static void lp_irq_mask(struct irq_data *d)
  {
  }
  
  static void lp_irq_enable(struct irq_data *d)
  {
  	struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
  	u32 hwirq = irqd_to_hwirq(d);
  	unsigned long reg = lp_gpio_reg(&lg->chip, hwirq, LP_INT_ENABLE);
  	unsigned long flags;
  
  	spin_lock_irqsave(&lg->lock, flags);
  	outl(inl(reg) | BIT(hwirq % 32), reg);
  	spin_unlock_irqrestore(&lg->lock, flags);
  }
  
  static void lp_irq_disable(struct irq_data *d)
  {
  	struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
  	u32 hwirq = irqd_to_hwirq(d);
  	unsigned long reg = lp_gpio_reg(&lg->chip, hwirq, LP_INT_ENABLE);
  	unsigned long flags;
  
  	spin_lock_irqsave(&lg->lock, flags);
  	outl(inl(reg) & ~BIT(hwirq % 32), reg);
  	spin_unlock_irqrestore(&lg->lock, flags);
  }
  
  static unsigned int lp_irq_startup(struct irq_data *d)
  {
  	struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
  
  	if (gpio_lock_as_irq(&lg->chip, irqd_to_hwirq(d)))
  		dev_err(lg->chip.dev,
  			"unable to lock HW IRQ %lu for IRQ
  ",
  			irqd_to_hwirq(d));
  	lp_irq_enable(d);
  	return 0;
  }
  
  static void lp_irq_shutdown(struct irq_data *d)
  {
  	struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
  
  	lp_irq_disable(d);
  	gpio_unlock_as_irq(&lg->chip, irqd_to_hwirq(d));
  }
  
  static struct irq_chip lp_irqchip = {
  	.name = "LP-GPIO",
  	.irq_mask = lp_irq_mask,
  	.irq_unmask = lp_irq_unmask,
  	.irq_enable = lp_irq_enable,
  	.irq_disable = lp_irq_disable,
  	.irq_set_type = lp_irq_type,
  	.irq_startup = lp_irq_startup,
  	.irq_shutdown = lp_irq_shutdown,
  	.flags = IRQCHIP_SKIP_SET_WAKE,
  };
  
  static void lp_gpio_irq_init_hw(struct lp_gpio *lg)
  {
  	unsigned long reg;
  	unsigned base;
  
  	for (base = 0; base < lg->chip.ngpio; base += 32) {
  		/* disable gpio pin interrupts */
  		reg = lp_gpio_reg(&lg->chip, base, LP_INT_ENABLE);
  		outl(0, reg);
  		/* Clear interrupt status register */
  		reg = lp_gpio_reg(&lg->chip, base, LP_INT_STAT);
  		outl(0xffffffff, reg);
  	}
  }
  
  static int lp_gpio_irq_map(struct irq_domain *d, unsigned int irq,
  			    irq_hw_number_t hwirq)
  {
  	struct lp_gpio *lg = d->host_data;
  
  	irq_set_chip_and_handler(irq, &lp_irqchip, handle_simple_irq);
  	irq_set_chip_data(irq, lg);
  	irq_set_irq_type(irq, IRQ_TYPE_NONE);
  
  	return 0;
  }
  
  static const struct irq_domain_ops lp_gpio_irq_ops = {
  	.map = lp_gpio_irq_map,
  };
  
  static int lp_gpio_probe(struct platform_device *pdev)
  {
  	struct lp_gpio *lg;
  	struct gpio_chip *gc;
  	struct resource *io_rc, *irq_rc;
  	struct device *dev = &pdev->dev;
  	unsigned long reg_len;
  	unsigned hwirq;
  	int ret = -ENODEV;
  
  	lg = devm_kzalloc(dev, sizeof(struct lp_gpio), GFP_KERNEL);
  	if (!lg) {
  		dev_err(dev, "can't allocate lp_gpio chip data
  ");
  		return -ENOMEM;
  	}
  
  	lg->pdev = pdev;
  	platform_set_drvdata(pdev, lg);
  
  	io_rc = platform_get_resource(pdev, IORESOURCE_IO, 0);
  	irq_rc = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  
  	if (!io_rc) {
  		dev_err(dev, "missing IO resources
  ");
  		return -EINVAL;
  	}
  
  	lg->reg_base = io_rc->start;
  	reg_len = resource_size(io_rc);
  
  	if (!devm_request_region(dev, lg->reg_base, reg_len, "lp-gpio")) {
  		dev_err(dev, "failed requesting IO region 0x%x
  ",
  			(unsigned int)lg->reg_base);
  		return -EBUSY;
  	}
  
  	spin_lock_init(&lg->lock);
  
  	gc = &lg->chip;
  	gc->label = dev_name(dev);
  	gc->owner = THIS_MODULE;
  	gc->request = lp_gpio_request;
  	gc->free = lp_gpio_free;
  	gc->direction_input = lp_gpio_direction_input;
  	gc->direction_output = lp_gpio_direction_output;
  	gc->get = lp_gpio_get;
  	gc->set = lp_gpio_set;
  	gc->base = -1;
  	gc->ngpio = LP_NUM_GPIO;
  	gc->can_sleep = false;
  	gc->dev = dev;
  
  	/* set up interrupts  */
  	if (irq_rc && irq_rc->start) {
  		hwirq = irq_rc->start;
  		gc->to_irq = lp_gpio_to_irq;
  
  		lg->domain = irq_domain_add_linear(NULL, LP_NUM_GPIO,
  						   &lp_gpio_irq_ops, lg);
  		if (!lg->domain)
  			return -ENXIO;
  
  		lp_gpio_irq_init_hw(lg);
  
  		irq_set_handler_data(hwirq, lg);
  		irq_set_chained_handler(hwirq, lp_gpio_irq_handler);
  	}
  
  	ret = gpiochip_add(gc);
  	if (ret) {
  		dev_err(dev, "failed adding lp-gpio chip
  ");
  		return ret;
  	}
  	pm_runtime_enable(dev);
  
  	return 0;
  }
  
  static int lp_gpio_runtime_suspend(struct device *dev)
  {
  	return 0;
  }
  
  static int lp_gpio_runtime_resume(struct device *dev)
  {
  	return 0;
  }
  
  static const struct dev_pm_ops lp_gpio_pm_ops = {
  	.runtime_suspend = lp_gpio_runtime_suspend,
  	.runtime_resume = lp_gpio_runtime_resume,
  };
  
  static const struct acpi_device_id lynxpoint_gpio_acpi_match[] = {
  	{ "INT33C7", 0 },
  	{ "INT3437", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(acpi, lynxpoint_gpio_acpi_match);
  
  static int lp_gpio_remove(struct platform_device *pdev)
  {
  	struct lp_gpio *lg = platform_get_drvdata(pdev);
  	int err;
  	pm_runtime_disable(&pdev->dev);
  	err = gpiochip_remove(&lg->chip);
  	if (err)
  		dev_warn(&pdev->dev, "failed to remove gpio_chip.
  ");
  	return 0;
  }
  
  static struct platform_driver lp_gpio_driver = {
  	.probe          = lp_gpio_probe,
  	.remove         = lp_gpio_remove,
  	.driver         = {
  		.name   = "lp_gpio",
  		.owner  = THIS_MODULE,
  		.pm	= &lp_gpio_pm_ops,
  		.acpi_match_table = ACPI_PTR(lynxpoint_gpio_acpi_match),
  	},
  };
  
  static int __init lp_gpio_init(void)
  {
  	return platform_driver_register(&lp_gpio_driver);
  }
  
  static void __exit lp_gpio_exit(void)
  {
  	platform_driver_unregister(&lp_gpio_driver);
  }
  
  subsys_initcall(lp_gpio_init);
  module_exit(lp_gpio_exit);
  
  MODULE_AUTHOR("Mathias Nyman (Intel)");
  MODULE_DESCRIPTION("GPIO interface for Intel Lynxpoint");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:lp_gpio");