/*
   * Texas Instruments Keystone IRQ controller IP driver
   *
   * Copyright (C) 2014 Texas Instruments, Inc.
   * Author: Sajesh Kumar Saran <sajesh@ti.com>
   *	   Grygorii Strashko <grygorii.strashko@ti.com>
   *
   * 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.
   *
   * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   * kind, whether express or implied; without even the implied warranty
   * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/irq.h>
  #include <linux/bitops.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/irqdomain.h>

  #include <linux/irqchip.h>

  #include <linux/irqchip/chained_irq.h>
  #include <linux/of.h>
  #include <linux/of_platform.h>
  #include <linux/mfd/syscon.h>
  #include <linux/regmap.h>

  
  /* The source ID bits start from 4 to 31 (total 28 bits)*/
  #define BIT_OFS			4
  #define KEYSTONE_N_IRQ		(32 - BIT_OFS)
  
  struct keystone_irq_device {
  	struct device		*dev;
  	struct irq_chip		 chip;
  	u32			 mask;

  	int			 irq;

  	struct irq_domain	*irqd;
  	struct regmap		*devctrl_regs;
  	u32			devctrl_offset;
  };
  
  static inline u32 keystone_irq_readl(struct keystone_irq_device *kirq)
  {
  	int ret;
  	u32 val = 0;
  
  	ret = regmap_read(kirq->devctrl_regs, kirq->devctrl_offset, &val);
  	if (ret < 0)
  		dev_dbg(kirq->dev, "irq read failed ret(%d)
  ", ret);
  	return val;
  }
  
  static inline void
  keystone_irq_writel(struct keystone_irq_device *kirq, u32 value)
  {
  	int ret;
  
  	ret = regmap_write(kirq->devctrl_regs, kirq->devctrl_offset, value);
  	if (ret < 0)
  		dev_dbg(kirq->dev, "irq write failed ret(%d)
  ", ret);
  }
  
  static void keystone_irq_setmask(struct irq_data *d)
  {
  	struct keystone_irq_device *kirq = irq_data_get_irq_chip_data(d);
  
  	kirq->mask |= BIT(d->hwirq);
  	dev_dbg(kirq->dev, "mask %lu [%x]
  ", d->hwirq, kirq->mask);
  }
  
  static void keystone_irq_unmask(struct irq_data *d)
  {
  	struct keystone_irq_device *kirq = irq_data_get_irq_chip_data(d);
  
  	kirq->mask &= ~BIT(d->hwirq);
  	dev_dbg(kirq->dev, "unmask %lu [%x]
  ", d->hwirq, kirq->mask);
  }
  
  static void keystone_irq_ack(struct irq_data *d)
  {
  	/* nothing to do here */
  }

  static void keystone_irq_handler(struct irq_desc *desc)

  {

  	unsigned int irq = irq_desc_get_irq(desc);

  	struct keystone_irq_device *kirq = irq_desc_get_handler_data(desc);
  	unsigned long pending;
  	int src, virq;
  
  	dev_dbg(kirq->dev, "start irq %d
  ", irq);
  
  	chained_irq_enter(irq_desc_get_chip(desc), desc);
  
  	pending = keystone_irq_readl(kirq);
  	keystone_irq_writel(kirq, pending);
  
  	dev_dbg(kirq->dev, "pending 0x%lx, mask 0x%x
  ", pending, kirq->mask);
  
  	pending = (pending >> BIT_OFS) & ~kirq->mask;
  
  	dev_dbg(kirq->dev, "pending after mask 0x%lx
  ", pending);
  
  	for (src = 0; src < KEYSTONE_N_IRQ; src++) {
  		if (BIT(src) & pending) {
  			virq = irq_find_mapping(kirq->irqd, src);
  			dev_dbg(kirq->dev, "dispatch bit %d, virq %d
  ",
  				src, virq);
  			if (!virq)

  				dev_warn(kirq->dev, "spurious irq detected hwirq %d, virq %d
  ",

  					 src, virq);
  			generic_handle_irq(virq);
  		}
  	}
  
  	chained_irq_exit(irq_desc_get_chip(desc), desc);
  
  	dev_dbg(kirq->dev, "end irq %d
  ", irq);
  }
  
  static int keystone_irq_map(struct irq_domain *h, unsigned int virq,
  				irq_hw_number_t hw)
  {
  	struct keystone_irq_device *kirq = h->host_data;
  
  	irq_set_chip_data(virq, kirq);
  	irq_set_chip_and_handler(virq, &kirq->chip, handle_level_irq);

  	irq_set_probe(virq);

  	return 0;
  }

  static const struct irq_domain_ops keystone_irq_ops = {

  	.map	= keystone_irq_map,
  	.xlate	= irq_domain_xlate_onecell,
  };
  
  static int keystone_irq_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct device_node *np = dev->of_node;
  	struct keystone_irq_device *kirq;
  	int ret;
  
  	if (np == NULL)
  		return -EINVAL;
  
  	kirq = devm_kzalloc(dev, sizeof(*kirq), GFP_KERNEL);
  	if (!kirq)
  		return -ENOMEM;
  
  	kirq->devctrl_regs =
  		syscon_regmap_lookup_by_phandle(np, "ti,syscon-dev");
  	if (IS_ERR(kirq->devctrl_regs))
  		return PTR_ERR(kirq->devctrl_regs);
  
  	ret = of_property_read_u32_index(np, "ti,syscon-dev", 1,
  					 &kirq->devctrl_offset);
  	if (ret) {
  		dev_err(dev, "couldn't read the devctrl_offset offset!
  ");
  		return ret;
  	}
  
  	kirq->irq = platform_get_irq(pdev, 0);
  	if (kirq->irq < 0) {
  		dev_err(dev, "no irq resource %d
  ", kirq->irq);
  		return kirq->irq;
  	}
  
  	kirq->dev = dev;
  	kirq->mask = ~0x0;
  	kirq->chip.name		= "keystone-irq";
  	kirq->chip.irq_ack	= keystone_irq_ack;
  	kirq->chip.irq_mask	= keystone_irq_setmask;
  	kirq->chip.irq_unmask	= keystone_irq_unmask;
  
  	kirq->irqd = irq_domain_add_linear(np, KEYSTONE_N_IRQ,
  					   &keystone_irq_ops, kirq);
  	if (!kirq->irqd) {
  		dev_err(dev, "IRQ domain registration failed
  ");
  		return -ENODEV;
  	}
  
  	platform_set_drvdata(pdev, kirq);

  	irq_set_chained_handler_and_data(kirq->irq, keystone_irq_handler, kirq);

  
  	/* clear all source bits */
  	keystone_irq_writel(kirq, ~0x0);
  
  	dev_info(dev, "irqchip registered, nr_irqs %u
  ", KEYSTONE_N_IRQ);
  
  	return 0;
  }
  
  static int keystone_irq_remove(struct platform_device *pdev)
  {
  	struct keystone_irq_device *kirq = platform_get_drvdata(pdev);
  	int hwirq;
  
  	for (hwirq = 0; hwirq < KEYSTONE_N_IRQ; hwirq++)
  		irq_dispose_mapping(irq_find_mapping(kirq->irqd, hwirq));
  
  	irq_domain_remove(kirq->irqd);
  	return 0;
  }
  
  static const struct of_device_id keystone_irq_dt_ids[] = {
  	{ .compatible = "ti,keystone-irq", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, keystone_irq_dt_ids);
  
  static struct platform_driver keystone_irq_device_driver = {
  	.probe		= keystone_irq_probe,
  	.remove		= keystone_irq_remove,
  	.driver		= {
  		.name	= "keystone_irq",

  		.of_match_table	= of_match_ptr(keystone_irq_dt_ids),
  	}
  };
  
  module_platform_driver(keystone_irq_device_driver);
  
  MODULE_AUTHOR("Texas Instruments");
  MODULE_AUTHOR("Sajesh Kumar Saran");
  MODULE_AUTHOR("Grygorii Strashko");
  MODULE_DESCRIPTION("Keystone IRQ chip");
  MODULE_LICENSE("GPL v2");