/*
   *  Support for Versatile FPGA-based IRQ controllers
   */

  #include <linux/bitops.h>

  #include <linux/irq.h>
  #include <linux/io.h>

  #include <linux/irqchip/versatile-fpga.h>

  #include <linux/irqdomain.h>
  #include <linux/module.h>

  #include <linux/of.h>
  #include <linux/of_address.h>

  #include <linux/of_irq.h>

  #include <asm/exception.h>

  #include <asm/mach/irq.h>

  #include "irqchip.h"

  #define IRQ_STATUS		0x00
  #define IRQ_RAW_STATUS		0x04
  #define IRQ_ENABLE_SET		0x08
  #define IRQ_ENABLE_CLEAR	0x0c

  #define INT_SOFT_SET		0x10
  #define INT_SOFT_CLEAR		0x14
  #define FIQ_STATUS		0x20
  #define FIQ_RAW_STATUS		0x24
  #define FIQ_ENABLE		0x28
  #define FIQ_ENABLE_SET		0x28
  #define FIQ_ENABLE_CLEAR	0x2C

  #define PIC_ENABLES             0x20	/* set interrupt pass through bits */

  /**
   * struct fpga_irq_data - irq data container for the FPGA IRQ controller
   * @base: memory offset in virtual memory

   * @chip: chip container for this instance
   * @domain: IRQ domain for this instance
   * @valid: mask for valid IRQs on this controller
   * @used_irqs: number of active IRQs on this controller
   */
  struct fpga_irq_data {
  	void __iomem *base;

  	struct irq_chip chip;
  	u32 valid;
  	struct irq_domain *domain;
  	u8 used_irqs;
  };
  
  /* we cannot allocate memory when the controllers are initially registered */

  static struct fpga_irq_data fpga_irq_devices[CONFIG_VERSATILE_FPGA_IRQ_NR];

  static int fpga_irq_id;

  static void fpga_irq_mask(struct irq_data *d)
  {
  	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);

  	u32 mask = 1 << d->hwirq;

  
  	writel(mask, f->base + IRQ_ENABLE_CLEAR);
  }
  
  static void fpga_irq_unmask(struct irq_data *d)
  {
  	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);

  	u32 mask = 1 << d->hwirq;

  
  	writel(mask, f->base + IRQ_ENABLE_SET);
  }
  
  static void fpga_irq_handle(unsigned int irq, struct irq_desc *desc)
  {

  	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);

  	u32 status = readl(f->base + IRQ_STATUS);
  
  	if (status == 0) {
  		do_bad_IRQ(irq, desc);
  		return;
  	}
  
  	do {
  		irq = ffs(status) - 1;
  		status &= ~(1 << irq);

  		generic_handle_irq(irq_find_mapping(f->domain, irq));

  	} while (status);
  }

  /*
   * Handle each interrupt in a single FPGA IRQ controller.  Returns non-zero
   * if we've handled at least one interrupt.  This does a single read of the
   * status register and handles all interrupts in order from LSB first.
   */
  static int handle_one_fpga(struct fpga_irq_data *f, struct pt_regs *regs)
  {
  	int handled = 0;
  	int irq;
  	u32 status;
  
  	while ((status  = readl(f->base + IRQ_STATUS))) {
  		irq = ffs(status) - 1;

  		handle_domain_irq(f->domain, irq, regs);

  		handled = 1;
  	}
  
  	return handled;
  }
  
  /*
   * Keep iterating over all registered FPGA IRQ controllers until there are
   * no pending interrupts.
   */
  asmlinkage void __exception_irq_entry fpga_handle_irq(struct pt_regs *regs)

  {

  	int i, handled;

  	do {
  		for (i = 0, handled = 0; i < fpga_irq_id; ++i)
  			handled |= handle_one_fpga(&fpga_irq_devices[i], regs);
  	} while (handled);
  }
  
  static int fpga_irqdomain_map(struct irq_domain *d, unsigned int irq,
  		irq_hw_number_t hwirq)
  {
  	struct fpga_irq_data *f = d->host_data;
  
  	/* Skip invalid IRQs, only register handlers for the real ones */

  	if (!(f->valid & BIT(hwirq)))

  		return -EPERM;

  	irq_set_chip_data(irq, f);
  	irq_set_chip_and_handler(irq, &f->chip,
  				handle_level_irq);
  	set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);

  	return 0;
  }
  
  static struct irq_domain_ops fpga_irqdomain_ops = {
  	.map = fpga_irqdomain_map,
  	.xlate = irq_domain_xlate_onetwocell,
  };

  void __init fpga_irq_init(void __iomem *base, const char *name, int irq_start,
  			  int parent_irq, u32 valid, struct device_node *node)
  {

  	struct fpga_irq_data *f;

  	int i;

  
  	if (fpga_irq_id >= ARRAY_SIZE(fpga_irq_devices)) {

  		pr_err("%s: too few FPGA IRQ controllers, increase CONFIG_VERSATILE_FPGA_IRQ_NR
  ", __func__);

  		return;

  	}

  	f = &fpga_irq_devices[fpga_irq_id];
  	f->base = base;

  	f->chip.name = name;

  	f->chip.irq_ack = fpga_irq_mask;
  	f->chip.irq_mask = fpga_irq_mask;
  	f->chip.irq_unmask = fpga_irq_unmask;

  	f->valid = valid;

  
  	if (parent_irq != -1) {

  		irq_set_handler_data(parent_irq, f);
  		irq_set_chained_handler(parent_irq, fpga_irq_handle);

  	}

  	/* This will also allocate irq descriptors */
  	f->domain = irq_domain_add_simple(node, fls(valid), irq_start,

  					  &fpga_irqdomain_ops, f);

  
  	/* This will allocate all valid descriptors in the linear case */
  	for (i = 0; i < fls(valid); i++)
  		if (valid & BIT(i)) {
  			if (!irq_start)
  				irq_create_mapping(f->domain, i);
  			f->used_irqs++;
  		}

  	pr_info("FPGA IRQ chip %d \"%s\" @ %p, %u irqs",

  		fpga_irq_id, name, base, f->used_irqs);

  	if (parent_irq != -1)
  		pr_cont(", parent IRQ: %d
  ", parent_irq);
  	else
  		pr_cont("
  ");

  
  	fpga_irq_id++;

  }

  #ifdef CONFIG_OF
  int __init fpga_irq_of_init(struct device_node *node,
  			    struct device_node *parent)
  {

  	void __iomem *base;
  	u32 clear_mask;
  	u32 valid_mask;

  	int parent_irq;

  
  	if (WARN_ON(!node))
  		return -ENODEV;
  
  	base = of_iomap(node, 0);
  	WARN(!base, "unable to map fpga irq registers
  ");
  
  	if (of_property_read_u32(node, "clear-mask", &clear_mask))
  		clear_mask = 0;
  
  	if (of_property_read_u32(node, "valid-mask", &valid_mask))
  		valid_mask = 0;

  	/* Some chips are cascaded from a parent IRQ */
  	parent_irq = irq_of_parse_and_map(node, 0);

  	if (!parent_irq) {
  		set_handle_irq(fpga_handle_irq);

  		parent_irq = -1;

  	}

  
  	fpga_irq_init(base, node->name, 0, parent_irq, valid_mask, node);

  
  	writel(clear_mask, base + IRQ_ENABLE_CLEAR);
  	writel(clear_mask, base + FIQ_ENABLE_CLEAR);

  	/*
  	 * On Versatile AB/PB, some secondary interrupts have a direct
  	 * pass-thru to the primary controller for IRQs 20 and 22-31 which need
  	 * to be enabled. See section 3.10 of the Versatile AB user guide.
  	 */
  	if (of_device_is_compatible(node, "arm,versatile-sic"))
  		writel(0xffd00000, base + PIC_ENABLES);

  	return 0;

  }

  IRQCHIP_DECLARE(arm_fpga, "arm,versatile-fpga-irq", fpga_irq_of_init);

  IRQCHIP_DECLARE(arm_fpga_sic, "arm,versatile-sic", fpga_irq_of_init);

  #endif