release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/powertv/asic/asic_int.c

   1 /*
   2  * Carsten Langgaard, carstenl@mips.com
   3  * Copyright (C) 2000, 2001, 2004 MIPS Technologies, Inc.
   4  * Copyright (C) 2001 Ralf Baechle
   5  * Portions copyright (C) 2009  Cisco Systems, Inc.
   6  *
   7  *  This program is free software; you can distribute it and/or modify it
   8  *  under the terms of the GNU General Public License (Version 2) as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope it will be useful, but WITHOUT
  12  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  *  for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License along
  17  *  with this program; if not, write to the Free Software Foundation, Inc.,
  18  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  19  *
  20  * Routines for generic manipulation of the interrupts found on the PowerTV
  21  * platform.
  22  *
  23  * The interrupt controller is located in the South Bridge a PIIX4 device
  24  * with two internal 82C95 interrupt controllers.
  25  */
  26 #include <linux/init.h>
  27 #include <linux/irq.h>
  28 #include <linux/sched.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/kernel_stat.h>
  31 #include <linux/kernel.h>
  32 #include <linux/random.h>
  33
  34 #include <asm/irq_cpu.h>
  35 #include <linux/io.h>
  36 #include <asm/irq_regs.h>
  37 #include <asm/mips-boards/generic.h>
  38
  39 #include <asm/mach-powertv/asic_regs.h>
  40
  41 static DEFINE_RAW_SPINLOCK(asic_irq_lock);
  42
  43 static inline int get_int(void)
  44 {
  45         unsigned long flags;
  46         int irq;
  47
  48         raw_spin_lock_irqsave(&asic_irq_lock, flags);
  49
  50         irq = (asic_read(int_int_scan) >> 4) - 1;
  51
  52         if (irq == 0 || irq >= NR_IRQS)
  53                 irq = -1;
  54
  55         raw_spin_unlock_irqrestore(&asic_irq_lock, flags);
  56
  57         return irq;
  58 }
  59
  60 static void asic_irqdispatch(void)
  61 {
  62         int irq;
  63
  64         irq = get_int();
  65         if (irq < 0)
  66                 return;  /* interrupt has already been cleared */
  67
  68         do_IRQ(irq);
  69 }
  70
  71 static inline int clz(unsigned long x)
  72 {
  73         __asm__(
  74         "       .set    push                                    \n"
  75         "       .set    mips32                                  \n"
  76         "       clz     %0, %1                                  \n"
  77         "       .set    pop                                     \n"
  78         : "=r" (x)
  79         : "r" (x));
  80
  81         return x;
  82 }
  83
  84 /*
  85  * Version of ffs that only looks at bits 12..15.
  86  */
  87 static inline unsigned int irq_ffs(unsigned int pending)
  88 {
  89         return fls(pending) - 1 + CAUSEB_IP;
  90 }
  91
  92 /*
  93  * TODO: check how it works under EIC mode.
  94  */
  95 asmlinkage void plat_irq_dispatch(void)
  96 {
  97         unsigned int pending = read_c0_cause() & read_c0_status() & ST0_IM;
  98         int irq;
  99
 100         irq = irq_ffs(pending);
 101
 102         if (irq == CAUSEF_IP3)
 103                 asic_irqdispatch();
 104         else if (irq >= 0)
 105                 do_IRQ(irq);
 106         else
 107                 spurious_interrupt();
 108 }
 109
 110 void __init arch_init_irq(void)
 111 {
 112         int i;
 113
 114         asic_irq_init();
 115
 116         /*
 117          * Initialize interrupt exception vectors.
 118          */
 119         if (cpu_has_veic || cpu_has_vint) {
 120                 int nvec = cpu_has_veic ? 64 : 8;
 121                 for (i = 0; i < nvec; i++)
 122                         set_vi_handler(i, asic_irqdispatch);
 123         }
 124 }