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mpc5121_ads_cpld.c

/*
 * Copyright (C) 2008 Freescale Semiconductor, Inc. All rights reserved.
 *
 * Author: John Rigby, <jrigby@freescale.com>
 *
 * Description:
 * MPC5121ADS CPLD irq handling
 *
 * This 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; either version 2 of the License, or
 * (at your option) any later version.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <asm/prom.h>

static struct device_node *cpld_pic_node;
static struct irq_host *cpld_pic_host;

/*
 * Bits to ignore in the misc_status register
 * 0x10 touch screen pendown is hard routed to irq1
 * 0x02 pci status is read from pci status register
 */
#define MISC_IGNORE 0x12

/*
 * Nothing to ignore in pci status register
 */
#define PCI_IGNORE 0x00

struct cpld_pic {
      u8 pci_mask;
      u8 pci_status;
      u8 route;
      u8 misc_mask;
      u8 misc_status;
      u8 misc_control;
};

static struct cpld_pic __iomem *cpld_regs;

static void __iomem *
irq_to_pic_mask(unsigned int irq)
{
      return irq <= 7 ? &cpld_regs->pci_mask : &cpld_regs->misc_mask;
}

static unsigned int
irq_to_pic_bit(unsigned int irq)
{
      return 1 << (irq & 0x7);
}

static void
cpld_mask_irq(unsigned int irq)
{
      unsigned int cpld_irq = (unsigned int)irq_map[irq].hwirq;
      void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);

      out_8(pic_mask,
            in_8(pic_mask) | irq_to_pic_bit(cpld_irq));
}

static void
cpld_unmask_irq(unsigned int irq)
{
      unsigned int cpld_irq = (unsigned int)irq_map[irq].hwirq;
      void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);

      out_8(pic_mask,
            in_8(pic_mask) & ~irq_to_pic_bit(cpld_irq));
}

static struct irq_chip cpld_pic = {
      .typename = " CPLD PIC ",
      .mask = cpld_mask_irq,
      .ack = cpld_mask_irq,
      .unmask = cpld_unmask_irq,
};

static int
cpld_pic_get_irq(int offset, u8 ignore, u8 __iomem *statusp,
                      u8 __iomem *maskp)
{
      int cpld_irq;
      u8 status = in_8(statusp);
      u8 mask = in_8(maskp);

      /* ignore don't cares and masked irqs */
      status |= (ignore | mask);

      if (status == 0xff)
            return NO_IRQ_IGNORE;

      cpld_irq = ffz(status) + offset;

      return irq_linear_revmap(cpld_pic_host, cpld_irq);
}

static void
cpld_pic_cascade(unsigned int irq, struct irq_desc *desc)
{
      irq = cpld_pic_get_irq(0, PCI_IGNORE, &cpld_regs->pci_status,
            &cpld_regs->pci_mask);
      if (irq != NO_IRQ && irq != NO_IRQ_IGNORE) {
            generic_handle_irq(irq);
            return;
      }

      irq = cpld_pic_get_irq(8, MISC_IGNORE, &cpld_regs->misc_status,
            &cpld_regs->misc_mask);
      if (irq != NO_IRQ && irq != NO_IRQ_IGNORE) {
            generic_handle_irq(irq);
            return;
      }
}

static int
cpld_pic_host_match(struct irq_host *h, struct device_node *node)
{
      return cpld_pic_node == node;
}

static int
cpld_pic_host_map(struct irq_host *h, unsigned int virq,
                       irq_hw_number_t hw)
{
      get_irq_desc(virq)->status |= IRQ_LEVEL;
      set_irq_chip_and_handler(virq, &cpld_pic, handle_level_irq);
      return 0;
}

static struct
irq_host_ops cpld_pic_host_ops = {
      .match = cpld_pic_host_match,
      .map = cpld_pic_host_map,
};

void __init
mpc5121_ads_cpld_map(void)
{
      struct device_node *np = NULL;

      np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
      if (!np) {
            printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
            return;
      }

      cpld_regs = of_iomap(np, 0);
      of_node_put(np);
}

void __init
mpc5121_ads_cpld_pic_init(void)
{
      unsigned int cascade_irq;
      struct device_node *np = NULL;

      pr_debug("cpld_ic_init\n");

      np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
      if (!np) {
            printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
            return;
      }

      if (!cpld_regs)
            goto end;

      cascade_irq = irq_of_parse_and_map(np, 0);
      if (cascade_irq == NO_IRQ)
            goto end;

      /*
       * statically route touch screen pendown through 1
       * and ignore it here
       * route all others through our cascade irq
       */
      out_8(&cpld_regs->route, 0xfd);
      out_8(&cpld_regs->pci_mask, 0xff);
      /* unmask pci ints in misc mask */
      out_8(&cpld_regs->misc_mask, ~(MISC_IGNORE));

      cpld_pic_node = of_node_get(np);

      cpld_pic_host =
          irq_alloc_host(np, IRQ_HOST_MAP_LINEAR, 16, &cpld_pic_host_ops, 16);
      if (!cpld_pic_host) {
            printk(KERN_ERR "CPLD PIC: failed to allocate irq host!\n");
            goto end;
      }

      set_irq_chained_handler(cascade_irq, cpld_pic_cascade);
end:
      of_node_put(np);
}

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