/*
   *  drivers/irqchip/irq-crossbar.c
   *
   *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
   *  Author: Sricharan R <r.sricharan@ti.com>
   *
   * 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.
   *
   */
  #include <linux/err.h>
  #include <linux/io.h>

  #include <linux/irqchip.h>

  #include <linux/irqdomain.h>

  #include <linux/of_address.h>
  #include <linux/of_irq.h>
  #include <linux/slab.h>

  #define IRQ_FREE	-1

  #define IRQ_RESERVED	-2

  #define IRQ_SKIP	-3

  #define GIC_IRQ_START	32

  /**
   * struct crossbar_device - crossbar device description

   * @lock: spinlock serializing access to @irq_map

   * @int_max: maximum number of supported interrupts

   * @safe_map: safe default value to initialize the crossbar

   * @max_crossbar_sources: Maximum number of crossbar sources

   * @irq_map: array of interrupts to crossbar number mapping
   * @crossbar_base: crossbar base address
   * @register_offsets: offsets for each irq number

   * @write: register write function pointer

   */
  struct crossbar_device {

  	raw_spinlock_t lock;

  	uint int_max;

  	uint safe_map;

  	uint max_crossbar_sources;

  	uint *irq_map;
  	void __iomem *crossbar_base;
  	int *register_offsets;

  	void (*write)(int, int);

  };
  
  static struct crossbar_device *cb;

  static void crossbar_writel(int irq_no, int cb_no)

  {
  	writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  }

  static void crossbar_writew(int irq_no, int cb_no)

  {
  	writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  }

  static void crossbar_writeb(int irq_no, int cb_no)

  {
  	writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  }

  static struct irq_chip crossbar_chip = {
  	.name			= "CBAR",
  	.irq_eoi		= irq_chip_eoi_parent,
  	.irq_mask		= irq_chip_mask_parent,
  	.irq_unmask		= irq_chip_unmask_parent,
  	.irq_retrigger		= irq_chip_retrigger_hierarchy,

  	.irq_set_type		= irq_chip_set_type_parent,

  	.flags			= IRQCHIP_MASK_ON_SUSPEND |
  				  IRQCHIP_SKIP_SET_WAKE,

  #ifdef CONFIG_SMP
  	.irq_set_affinity	= irq_chip_set_affinity_parent,
  #endif
  };

  static int allocate_gic_irq(struct irq_domain *domain, unsigned virq,
  			    irq_hw_number_t hwirq)

  {

  	struct irq_fwspec fwspec;

  	int i;

  	int err;

  	if (!irq_domain_get_of_node(domain->parent))
  		return -EINVAL;

  	raw_spin_lock(&cb->lock);

  	for (i = cb->int_max - 1; i >= 0; i--) {

  		if (cb->irq_map[i] == IRQ_FREE) {

  			cb->irq_map[i] = hwirq;
  			break;

  		}
  	}

  	raw_spin_unlock(&cb->lock);

  	if (i < 0)
  		return -ENODEV;

  	fwspec.fwnode = domain->parent->fwnode;
  	fwspec.param_count = 3;
  	fwspec.param[0] = 0;	/* SPI */
  	fwspec.param[1] = i;
  	fwspec.param[2] = IRQ_TYPE_LEVEL_HIGH;

  	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);

  	if (err)
  		cb->irq_map[i] = IRQ_FREE;
  	else
  		cb->write(i, hwirq);

  	return err;

  }

  static int crossbar_domain_alloc(struct irq_domain *d, unsigned int virq,
  				 unsigned int nr_irqs, void *data)

  {

  	struct irq_fwspec *fwspec = data;

  	irq_hw_number_t hwirq;
  	int i;

  	if (fwspec->param_count != 3)

  		return -EINVAL;	/* Not GIC compliant */

  	if (fwspec->param[0] != 0)

  		return -EINVAL;	/* No PPI should point to this domain */

  	hwirq = fwspec->param[1];

  	if ((hwirq + nr_irqs) > cb->max_crossbar_sources)
  		return -EINVAL;	/* Can't deal with this */
  
  	for (i = 0; i < nr_irqs; i++) {
  		int err = allocate_gic_irq(d, virq + i, hwirq + i);
  
  		if (err)
  			return err;
  
  		irq_domain_set_hwirq_and_chip(d, virq + i, hwirq + i,
  					      &crossbar_chip, NULL);
  	}

  	return 0;
  }

  /**

   * crossbar_domain_free - unmap/free a crossbar<->irq connection
   * @domain: domain of irq to unmap
   * @virq: virq number
   * @nr_irqs: number of irqs to free

   *
   * We do not maintain a use count of total number of map/unmap
   * calls for a particular irq to find out if a irq can be really
   * unmapped. This is because unmap is called during irq_dispose_mapping(irq),
   * after which irq is anyways unusable. So an explicit map has to be called
   * after that.
   */

  static void crossbar_domain_free(struct irq_domain *domain, unsigned int virq,
  				 unsigned int nr_irqs)

  {

  	int i;

  	raw_spin_lock(&cb->lock);
  	for (i = 0; i < nr_irqs; i++) {
  		struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);
  
  		irq_domain_reset_irq_data(d);
  		cb->irq_map[d->hwirq] = IRQ_FREE;
  		cb->write(d->hwirq, cb->safe_map);

  	}

  	raw_spin_unlock(&cb->lock);

  }

  static int crossbar_domain_translate(struct irq_domain *d,
  				     struct irq_fwspec *fwspec,
  				     unsigned long *hwirq,
  				     unsigned int *type)

  {

  	if (is_of_node(fwspec->fwnode)) {
  		if (fwspec->param_count != 3)
  			return -EINVAL;

  		/* No PPI should point to this domain */
  		if (fwspec->param[0] != 0)
  			return -EINVAL;
  
  		*hwirq = fwspec->param[1];

  		*type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;

  		return 0;
  	}
  
  	return -EINVAL;

  }

  static const struct irq_domain_ops crossbar_domain_ops = {

  	.alloc		= crossbar_domain_alloc,
  	.free		= crossbar_domain_free,
  	.translate	= crossbar_domain_translate,

  };
  
  static int __init crossbar_of_init(struct device_node *node)
  {

  	int i, size, max = 0, reserved = 0, entry;

  	const __be32 *irqsr;

  	int ret = -ENOMEM;

  	cb = kzalloc(sizeof(*cb), GFP_KERNEL);

  
  	if (!cb)

  		return ret;

  
  	cb->crossbar_base = of_iomap(node, 0);
  	if (!cb->crossbar_base)

  		goto err_cb;

  	of_property_read_u32(node, "ti,max-crossbar-sources",
  			     &cb->max_crossbar_sources);
  	if (!cb->max_crossbar_sources) {
  		pr_err("missing 'ti,max-crossbar-sources' property
  ");
  		ret = -EINVAL;
  		goto err_base;
  	}

  	of_property_read_u32(node, "ti,max-irqs", &max);

  	if (!max) {
  		pr_err("missing 'ti,max-irqs' property
  ");
  		ret = -EINVAL;

  		goto err_base;

  	}

  	cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);

  	if (!cb->irq_map)

  		goto err_base;

  
  	cb->int_max = max;
  
  	for (i = 0; i < max; i++)
  		cb->irq_map[i] = IRQ_FREE;
  
  	/* Get and mark reserved irqs */
  	irqsr = of_get_property(node, "ti,irqs-reserved", &size);
  	if (irqsr) {
  		size /= sizeof(__be32);
  
  		for (i = 0; i < size; i++) {
  			of_property_read_u32_index(node,
  						   "ti,irqs-reserved",
  						   i, &entry);

  			if (entry >= max) {

  				pr_err("Invalid reserved entry
  ");

  				ret = -EINVAL;

  				goto err_irq_map;

  			}

  			cb->irq_map[entry] = IRQ_RESERVED;

  		}
  	}

  	/* Skip irqs hardwired to bypass the crossbar */
  	irqsr = of_get_property(node, "ti,irqs-skip", &size);
  	if (irqsr) {
  		size /= sizeof(__be32);
  
  		for (i = 0; i < size; i++) {
  			of_property_read_u32_index(node,
  						   "ti,irqs-skip",
  						   i, &entry);

  			if (entry >= max) {

  				pr_err("Invalid skip entry
  ");
  				ret = -EINVAL;

  				goto err_irq_map;

  			}
  			cb->irq_map[entry] = IRQ_SKIP;
  		}
  	}

  	cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);

  	if (!cb->register_offsets)

  		goto err_irq_map;

  
  	of_property_read_u32(node, "ti,reg-size", &size);
  
  	switch (size) {
  	case 1:
  		cb->write = crossbar_writeb;
  		break;
  	case 2:
  		cb->write = crossbar_writew;
  		break;
  	case 4:
  		cb->write = crossbar_writel;
  		break;
  	default:
  		pr_err("Invalid reg-size property
  ");

  		ret = -EINVAL;

  		goto err_reg_offset;

  		break;
  	}
  
  	/*
  	 * Register offsets are not linear because of the
  	 * reserved irqs. so find and store the offsets once.
  	 */
  	for (i = 0; i < max; i++) {

  		if (cb->irq_map[i] == IRQ_RESERVED)

  			continue;
  
  		cb->register_offsets[i] = reserved;
  		reserved += size;
  	}

  	of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);

  	/* Initialize the crossbar with safe map to start with */
  	for (i = 0; i < max; i++) {
  		if (cb->irq_map[i] == IRQ_RESERVED ||
  		    cb->irq_map[i] == IRQ_SKIP)
  			continue;
  
  		cb->write(i, cb->safe_map);
  	}

  	raw_spin_lock_init(&cb->lock);

  	return 0;

  err_reg_offset:

  	kfree(cb->register_offsets);

  err_irq_map:

  	kfree(cb->irq_map);

  err_base:

  	iounmap(cb->crossbar_base);

  err_cb:

  	kfree(cb);

  
  	cb = NULL;

  	return ret;

  }

  static int __init irqcrossbar_init(struct device_node *node,
  				   struct device_node *parent)

  {

  	struct irq_domain *parent_domain, *domain;
  	int err;
  
  	if (!parent) {
  		pr_err("%s: no parent, giving up
  ", node->full_name);

  		return -ENODEV;

  	}
  
  	parent_domain = irq_find_host(parent);
  	if (!parent_domain) {
  		pr_err("%s: unable to obtain parent domain
  ", node->full_name);
  		return -ENXIO;
  	}
  
  	err = crossbar_of_init(node);
  	if (err)
  		return err;
  
  	domain = irq_domain_add_hierarchy(parent_domain, 0,
  					  cb->max_crossbar_sources,
  					  node, &crossbar_domain_ops,
  					  NULL);
  	if (!domain) {
  		pr_err("%s: failed to allocated domain
  ", node->full_name);
  		return -ENOMEM;
  	}

  	return 0;
  }

  
  IRQCHIP_DECLARE(ti_irqcrossbar, "ti,irq-crossbar", irqcrossbar_init);