/*
   * Support for the GPIO/IRQ expander chips present on several HTC phones.
   * These are implemented in CPLD chips present on the board.
   *
   * Copyright (c) 2007 Kevin O'Connor <kevin@koconnor.net>
   * Copyright (c) 2007 Philipp Zabel <philipp.zabel@gmail.com>
   *
   * This file may be distributed under the terms of the GNU GPL license.
   */
  
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/io.h>
  #include <linux/spinlock.h>

  #include <linux/platform_data/gpio-htc-egpio.h>

  #include <linux/platform_device.h>

  #include <linux/slab.h>

  #include <linux/module.h>

  
  struct egpio_chip {
  	int              reg_start;
  	int              cached_values;
  	unsigned long    is_out;
  	struct device    *dev;
  	struct gpio_chip chip;
  };
  
  struct egpio_info {
  	spinlock_t        lock;
  
  	/* iomem info */
  	void __iomem      *base_addr;
  	int               bus_shift;	/* byte shift */
  	int               reg_shift;	/* bit shift */
  	int               reg_mask;
  
  	/* irq info */
  	int               ack_register;
  	int               ack_write;
  	u16               irqs_enabled;
  	uint              irq_start;
  	int               nirqs;
  	uint              chained_irq;
  
  	/* egpio info */
  	struct egpio_chip *chip;
  	int               nchips;
  };
  
  static inline void egpio_writew(u16 value, struct egpio_info *ei, int reg)
  {
  	writew(value, ei->base_addr + (reg << ei->bus_shift));
  }
  
  static inline u16 egpio_readw(struct egpio_info *ei, int reg)
  {
  	return readw(ei->base_addr + (reg << ei->bus_shift));
  }
  
  /*
   * IRQs
   */
  
  static inline void ack_irqs(struct egpio_info *ei)
  {
  	egpio_writew(ei->ack_write, ei, ei->ack_register);
  	pr_debug("EGPIO ack - write %x to base+%x
  ",
  			ei->ack_write, ei->ack_register << ei->bus_shift);
  }

  static void egpio_ack(struct irq_data *data)

  {
  }
  
  /* There does not appear to be a way to proactively mask interrupts
   * on the egpio chip itself.  So, we simply ignore interrupts that
   * aren't desired. */

  static void egpio_mask(struct irq_data *data)

  {

  	struct egpio_info *ei = irq_data_get_irq_chip_data(data);
  	ei->irqs_enabled &= ~(1 << (data->irq - ei->irq_start));
  	pr_debug("EGPIO mask %d %04x
  ", data->irq, ei->irqs_enabled);

  }

  
  static void egpio_unmask(struct irq_data *data)

  {

  	struct egpio_info *ei = irq_data_get_irq_chip_data(data);
  	ei->irqs_enabled |= 1 << (data->irq - ei->irq_start);
  	pr_debug("EGPIO unmask %d %04x
  ", data->irq, ei->irqs_enabled);

  }
  
  static struct irq_chip egpio_muxed_chip = {

  	.name		= "htc-egpio",
  	.irq_ack	= egpio_ack,
  	.irq_mask	= egpio_mask,
  	.irq_unmask	= egpio_unmask,

  };

  static void egpio_handler(struct irq_desc *desc)

  {

  	struct egpio_info *ei = irq_desc_get_handler_data(desc);

  	int irqpin;
  
  	/* Read current pins. */
  	unsigned long readval = egpio_readw(ei, ei->ack_register);
  	pr_debug("IRQ reg: %x
  ", (unsigned int)readval);
  	/* Ack/unmask interrupts. */
  	ack_irqs(ei);
  	/* Process all set pins. */
  	readval &= ei->irqs_enabled;

  	for_each_set_bit(irqpin, &readval, ei->nirqs) {

  		/* Run irq handler */
  		pr_debug("got IRQ %d
  ", irqpin);

  		generic_handle_irq(ei->irq_start + irqpin);

  	}
  }
  
  int htc_egpio_get_wakeup_irq(struct device *dev)
  {
  	struct egpio_info *ei = dev_get_drvdata(dev);
  
  	/* Read current pins. */
  	u16 readval = egpio_readw(ei, ei->ack_register);
  	/* Ack/unmask interrupts. */
  	ack_irqs(ei);
  	/* Return first set pin. */
  	readval &= ei->irqs_enabled;
  	return ei->irq_start + ffs(readval) - 1;
  }
  EXPORT_SYMBOL(htc_egpio_get_wakeup_irq);
  
  static inline int egpio_pos(struct egpio_info *ei, int bit)
  {
  	return bit >> ei->reg_shift;
  }
  
  static inline int egpio_bit(struct egpio_info *ei, int bit)
  {
  	return 1 << (bit & ((1 << ei->reg_shift)-1));
  }
  
  /*
   * Input pins
   */
  
  static int egpio_get(struct gpio_chip *chip, unsigned offset)
  {
  	struct egpio_chip *egpio;
  	struct egpio_info *ei;
  	unsigned           bit;
  	int                reg;
  	int                value;
  
  	pr_debug("egpio_get_value(%d)
  ", chip->base + offset);

  	egpio = gpiochip_get_data(chip);

  	ei    = dev_get_drvdata(egpio->dev);
  	bit   = egpio_bit(ei, offset);
  	reg   = egpio->reg_start + egpio_pos(ei, offset);
  
  	value = egpio_readw(ei, reg);
  	pr_debug("readw(%p + %x) = %x
  ",
  			ei->base_addr, reg << ei->bus_shift, value);

  	return !!(value & bit);

  }
  
  static int egpio_direction_input(struct gpio_chip *chip, unsigned offset)
  {
  	struct egpio_chip *egpio;

  	egpio = gpiochip_get_data(chip);

  	return test_bit(offset, &egpio->is_out) ? -EINVAL : 0;
  }
  
  
  /*
   * Output pins
   */
  
  static void egpio_set(struct gpio_chip *chip, unsigned offset, int value)
  {
  	unsigned long     flag;
  	struct egpio_chip *egpio;
  	struct egpio_info *ei;
  	unsigned          bit;
  	int               pos;
  	int               reg;
  	int               shift;
  
  	pr_debug("egpio_set(%s, %d(%d), %d)
  ",
  			chip->label, offset, offset+chip->base, value);

  	egpio = gpiochip_get_data(chip);

  	ei    = dev_get_drvdata(egpio->dev);
  	bit   = egpio_bit(ei, offset);
  	pos   = egpio_pos(ei, offset);
  	reg   = egpio->reg_start + pos;
  	shift = pos << ei->reg_shift;
  
  	pr_debug("egpio %s: reg %d = 0x%04x
  ", value ? "set" : "clear",
  			reg, (egpio->cached_values >> shift) & ei->reg_mask);
  
  	spin_lock_irqsave(&ei->lock, flag);
  	if (value)
  		egpio->cached_values |= (1 << offset);
  	else
  		egpio->cached_values &= ~(1 << offset);
  	egpio_writew((egpio->cached_values >> shift) & ei->reg_mask, ei, reg);
  	spin_unlock_irqrestore(&ei->lock, flag);
  }
  
  static int egpio_direction_output(struct gpio_chip *chip,
  					unsigned offset, int value)
  {
  	struct egpio_chip *egpio;

  	egpio = gpiochip_get_data(chip);

  	if (test_bit(offset, &egpio->is_out)) {
  		egpio_set(chip, offset, value);
  		return 0;
  	} else {
  		return -EINVAL;
  	}
  }
  
  static void egpio_write_cache(struct egpio_info *ei)
  {
  	int               i;
  	struct egpio_chip *egpio;
  	int               shift;
  
  	for (i = 0; i < ei->nchips; i++) {
  		egpio = &(ei->chip[i]);
  		if (!egpio->is_out)
  			continue;
  
  		for (shift = 0; shift < egpio->chip.ngpio;
  				shift += (1<<ei->reg_shift)) {
  
  			int reg = egpio->reg_start + egpio_pos(ei, shift);
  
  			if (!((egpio->is_out >> shift) & ei->reg_mask))
  				continue;
  
  			pr_debug("EGPIO: setting %x to %x, was %x
  ", reg,
  				(egpio->cached_values >> shift) & ei->reg_mask,
  				egpio_readw(ei, reg));
  
  			egpio_writew((egpio->cached_values >> shift)
  					& ei->reg_mask, ei, reg);
  		}
  	}
  }
  
  
  /*
   * Setup
   */
  
  static int __init egpio_probe(struct platform_device *pdev)
  {

  	struct htc_egpio_platform_data *pdata = dev_get_platdata(&pdev->dev);

  	struct resource   *res;
  	struct egpio_info *ei;
  	struct gpio_chip  *chip;
  	unsigned int      irq, irq_end;
  	int               i;
  	int               ret;
  
  	/* Initialize ei data structure. */

  	ei = devm_kzalloc(&pdev->dev, sizeof(*ei), GFP_KERNEL);

  	if (!ei)
  		return -ENOMEM;
  
  	spin_lock_init(&ei->lock);
  
  	/* Find chained irq */
  	ret = -EINVAL;
  	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	if (res)
  		ei->chained_irq = res->start;
  
  	/* Map egpio chip into virtual address space. */
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		goto fail;

  	ei->base_addr = devm_ioremap_nocache(&pdev->dev, res->start,
  					     resource_size(res));

  	if (!ei->base_addr)
  		goto fail;

  	pr_debug("EGPIO phys=%08x virt=%p
  ", (u32)res->start, ei->base_addr);

  
  	if ((pdata->bus_width != 16) && (pdata->bus_width != 32))
  		goto fail;
  	ei->bus_shift = fls(pdata->bus_width - 1) - 3;
  	pr_debug("bus_shift = %d
  ", ei->bus_shift);
  
  	if ((pdata->reg_width != 8) && (pdata->reg_width != 16))
  		goto fail;
  	ei->reg_shift = fls(pdata->reg_width - 1);
  	pr_debug("reg_shift = %d
  ", ei->reg_shift);
  
  	ei->reg_mask = (1 << pdata->reg_width) - 1;
  
  	platform_set_drvdata(pdev, ei);
  
  	ei->nchips = pdata->num_chips;

  	ei->chip = devm_kzalloc(&pdev->dev,
  				sizeof(struct egpio_chip) * ei->nchips,
  				GFP_KERNEL);

  	if (!ei->chip) {

  		ret = -ENOMEM;
  		goto fail;
  	}
  	for (i = 0; i < ei->nchips; i++) {
  		ei->chip[i].reg_start = pdata->chip[i].reg_start;
  		ei->chip[i].cached_values = pdata->chip[i].initial_values;
  		ei->chip[i].is_out = pdata->chip[i].direction;
  		ei->chip[i].dev = &(pdev->dev);
  		chip = &(ei->chip[i].chip);
  		chip->label           = "htc-egpio";

  		chip->parent          = &pdev->dev;

  		chip->owner           = THIS_MODULE;

  		chip->get             = egpio_get;
  		chip->set             = egpio_set;
  		chip->direction_input = egpio_direction_input;
  		chip->direction_output = egpio_direction_output;
  		chip->base            = pdata->chip[i].gpio_base;
  		chip->ngpio           = pdata->chip[i].num_gpios;

  		gpiochip_add_data(chip, &ei->chip[i]);

  	}
  
  	/* Set initial pin values */
  	egpio_write_cache(ei);
  
  	ei->irq_start = pdata->irq_base;
  	ei->nirqs = pdata->num_irqs;
  	ei->ack_register = pdata->ack_register;
  
  	if (ei->chained_irq) {
  		/* Setup irq handlers */
  		ei->ack_write = 0xFFFF;
  		if (pdata->invert_acks)
  			ei->ack_write = 0;
  		irq_end = ei->irq_start + ei->nirqs;
  		for (irq = ei->irq_start; irq < irq_end; irq++) {

  			irq_set_chip_and_handler(irq, &egpio_muxed_chip,
  						 handle_simple_irq);

  			irq_set_chip_data(irq, ei);

  			irq_clear_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);

  		}

  		irq_set_irq_type(ei->chained_irq, IRQ_TYPE_EDGE_RISING);

  		irq_set_chained_handler_and_data(ei->chained_irq,
  						 egpio_handler, ei);

  		ack_irqs(ei);
  
  		device_init_wakeup(&pdev->dev, 1);
  	}
  
  	return 0;
  
  fail:
  	printk(KERN_ERR "EGPIO failed to setup
  ");

  	return ret;
  }
  
  static int __exit egpio_remove(struct platform_device *pdev)
  {
  	struct egpio_info *ei = platform_get_drvdata(pdev);
  	unsigned int      irq, irq_end;
  
  	if (ei->chained_irq) {
  		irq_end = ei->irq_start + ei->nirqs;
  		for (irq = ei->irq_start; irq < irq_end; irq++) {

  			irq_set_chip_and_handler(irq, NULL, NULL);

  			irq_set_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);

  		}

  		irq_set_chained_handler(ei->chained_irq, NULL);

  		device_init_wakeup(&pdev->dev, 0);
  	}

  
  	return 0;
  }
  
  #ifdef CONFIG_PM
  static int egpio_suspend(struct platform_device *pdev, pm_message_t state)
  {
  	struct egpio_info *ei = platform_get_drvdata(pdev);
  
  	if (ei->chained_irq && device_may_wakeup(&pdev->dev))
  		enable_irq_wake(ei->chained_irq);
  	return 0;
  }
  
  static int egpio_resume(struct platform_device *pdev)
  {
  	struct egpio_info *ei = platform_get_drvdata(pdev);
  
  	if (ei->chained_irq && device_may_wakeup(&pdev->dev))
  		disable_irq_wake(ei->chained_irq);
  
  	/* Update registers from the cache, in case
  	   the CPLD was powered off during suspend */
  	egpio_write_cache(ei);
  	return 0;
  }
  #else
  #define egpio_suspend NULL
  #define egpio_resume NULL
  #endif
  
  
  static struct platform_driver egpio_driver = {
  	.driver = {
  		.name = "htc-egpio",
  	},
  	.remove       = __exit_p(egpio_remove),
  	.suspend      = egpio_suspend,
  	.resume       = egpio_resume,
  };
  
  static int __init egpio_init(void)
  {
  	return platform_driver_probe(&egpio_driver, egpio_probe);
  }
  
  static void __exit egpio_exit(void)
  {
  	platform_driver_unregister(&egpio_driver);
  }
  
  /* start early for dependencies */
  subsys_initcall(egpio_init);
  module_exit(egpio_exit)
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Kevin O'Connor <kevin@koconnor.net>");