arch/mips/momentum/ocelot_g/gt-irq.c

   1 /*
   2  *
   3  * Copyright 2002 Momentum Computer
   4  * Author: mdharm@momenco.com
   5  *
   6  * arch/mips/momentum/ocelot_g/gt_irq.c
   7  *     Interrupt routines for gt64240.  Currently it only handles timer irq.
   8  *
   9  * This program is free software; you can redistribute  it and/or modify it
  10  * under  the terms of  the GNU General  Public License as published by the
  11  * Free Software Foundation;  either version 2 of the  License, or (at your
  12  * option) any later version.
  13  */
  14 #include <linux/config.h>
  15 #include <linux/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel.h>
  18 #include <asm/ptrace.h>
  19 #include <linux/sched.h>
  20 #include <linux/kernel_stat.h>
  21 #include <asm/gt64240.h>
  22 #include <asm/io.h>
  23
  24 unsigned long bus_clock;
  25
  26 /*
  27  * These are interrupt handlers for the GT on-chip interrupts.  They
  28  * all come in to the MIPS on a single interrupt line, and have to
  29  * be handled and ack'ed differently than other MIPS interrupts.
  30  */
  31
  32 #if CURRENTLY_UNUSED
  33
  34 struct tq_struct irq_handlers[MAX_CAUSE_REGS][MAX_CAUSE_REG_WIDTH];
  35 void hook_irq_handler(int int_cause, int bit_num, void *isr_ptr);
  36
  37 /*
  38  * Hooks IRQ handler to the system. When the system is interrupted
  39  * the interrupt service routine is called.
  40  *
  41  * Inputs :
  42  * int_cause - The interrupt cause number. In EVB64120 two parameters
  43  *             are declared, INT_CAUSE_MAIN and INT_CAUSE_HIGH.
  44  * bit_num   - Indicates which bit number in the cause register
  45  * isr_ptr   - Pointer to the interrupt service routine
  46  */
  47 void hook_irq_handler(int int_cause, int bit_num, void *isr_ptr)
  48 {
  49         irq_handlers[int_cause][bit_num].routine = isr_ptr;
  50 }
  51
  52
  53 /*
  54  * Enables the IRQ on Galileo Chip
  55  *
  56  * Inputs :
  57  * int_cause - The interrupt cause number. In EVB64120 two parameters
  58  *             are declared, INT_CAUSE_MAIN and INT_CAUSE_HIGH.
  59  * bit_num   - Indicates which bit number in the cause register
  60  *
  61  * Outputs :
  62  * 1 if succesful, 0 if failure
  63  */
  64 int enable_galileo_irq(int int_cause, int bit_num)
  65 {
  66         if (int_cause == INT_CAUSE_MAIN)
  67                 SET_REG_BITS(CPU_INTERRUPT_MASK_REGISTER, (1 << bit_num));
  68         else if (int_cause == INT_CAUSE_HIGH)
  69                 SET_REG_BITS(CPU_HIGH_INTERRUPT_MASK_REGISTER,
  70                              (1 << bit_num));
  71         else
  72                 return 0;
  73
  74         return 1;
  75 }
  76
  77 /*
  78  * Disables the IRQ on Galileo Chip
  79  *
  80  * Inputs :
  81  * int_cause - The interrupt cause number. In EVB64120 two parameters
  82  *             are declared, INT_CAUSE_MAIN and INT_CAUSE_HIGH.
  83  * bit_num   - Indicates which bit number in the cause register
  84  *
  85  * Outputs :
  86  * 1 if succesful, 0 if failure
  87  */
  88 int disable_galileo_irq(int int_cause, int bit_num)
  89 {
  90         if (int_cause == INT_CAUSE_MAIN)
  91                 RESET_REG_BITS(CPU_INTERRUPT_MASK_REGISTER,
  92                                (1 << bit_num));
  93         else if (int_cause == INT_CAUSE_HIGH)
  94                 RESET_REG_BITS(CPU_HIGH_INTERRUPT_MASK_REGISTER,
  95                                (1 << bit_num));
  96         else
  97                 return 0;
  98         return 1;
  99 }
 100 #endif                          /*  UNUSED  */
 101
 102 /*
 103  * Interrupt handler for interrupts coming from the Galileo chip via P0_INT#.
 104  *
 105  * We route the timer interrupt to P0_INT# (IRQ 6), and that's all this
 106  * routine can handle, for now.
 107  *
 108  * In the future, we'll route more interrupts to this pin, and that's why
 109  * we keep this particular structure in the function.
 110  */
 111
 112 static irqreturn_t gt64240_p0int_irq(int irq, void *dev, struct pt_regs *regs)
 113 {
 114         uint32_t irq_src, irq_src_mask;
 115         int handled;
 116
 117         /* get the low interrupt cause register */
 118         irq_src = MV_READ(LOW_INTERRUPT_CAUSE_REGISTER);
 119
 120         /* get the mask register for this pin */
 121         irq_src_mask = MV_READ(PCI_0INTERRUPT_CAUSE_MASK_REGISTER_LOW);
 122
 123         /* mask off only the interrupts we're interested in */
 124         irq_src = irq_src & irq_src_mask;
 125
 126         handled = IRQ_NONE;
 127
 128         /* Check for timer interrupt */
 129         if (irq_src & 0x00000100) {
 130                 handled = IRQ_HANDLED;
 131                 irq_src &= ~0x00000100;
 132
 133                 /* Clear any pending cause bits */
 134                 MV_WRITE(TIMER_COUNTER_0_3_INTERRUPT_CAUSE, 0x0);
 135
 136                 /* handle the timer call */
 137                 do_timer(regs);
 138 #ifndef CONFIG_SMP
 139                 update_process_times(user_mode(regs));
 140 #endif
 141         }
 142
 143         if (irq_src) {
 144                 printk(KERN_INFO
 145                        "UNKNOWN P0_INT# interrupt received, irq_src=0x%x\n",
 146                        irq_src);
 147         }
 148
 149         return handled;
 150 }
 151
 152 /*
 153  * Initializes timer using galileo's built in timer.
 154  */
 155
 156 /*
 157  * This will ignore the standard MIPS timer interrupt handler
 158  * that is passed in as *irq (=irq0 in ../kernel/time.c).
 159  * We will do our own timer interrupt handling.
 160  */
 161 void gt64240_time_init(void)
 162 {
 163         static struct irqaction timer;
 164
 165         /* Stop the timer -- we'll use timer #0 */
 166         MV_WRITE(TIMER_COUNTER_0_3_CONTROL, 0x0);
 167
 168         /* Load timer value for 100 Hz */
 169         MV_WRITE(TIMER_COUNTER0, bus_clock / 100);
 170
 171         /*
 172          * Create the IRQ structure entry for the timer.  Since we're too early
 173          * in the boot process to use the "request_irq()" call, we'll hard-code
 174          * the values to the correct interrupt line.
 175          */
 176         timer.handler = &gt64240_p0int_irq;
 177         timer.flags = SA_SHIRQ | SA_INTERRUPT;
 178         timer.name = "timer";
 179         timer.dev_id = NULL;
 180         timer.next = NULL;
 181         timer.mask = 0;
 182         irq_desc[6].action = &timer;
 183
 184         enable_irq(6);
 185
 186         /* Clear any pending cause bits */
 187         MV_WRITE(TIMER_COUNTER_0_3_INTERRUPT_CAUSE, 0x0);
 188
 189         /* Enable the interrupt for timer 0 */
 190         MV_WRITE(TIMER_COUNTER_0_3_INTERRUPT_MASK, 0x1);
 191
 192         /* Enable the timer interrupt for GT-64240 pin P0_INT# */
 193         MV_WRITE (PCI_0INTERRUPT_CAUSE_MASK_REGISTER_LOW, 0x100);
 194
 195         /* Configure and start the timer */
 196         MV_WRITE(TIMER_COUNTER_0_3_CONTROL, 0x3);
 197 }
 198
 199 void gt64240_irq_init(void)
 200 {
 201 #if CURRENTLY_UNUSED
 202         int i, j;
 203
 204         /* Reset irq handlers pointers to NULL */
 205         for (i = 0; i < MAX_CAUSE_REGS; i++) {
 206                 for (j = 0; j < MAX_CAUSE_REG_WIDTH; j++) {
 207                         irq_handlers[i][j].next = NULL;
 208                         irq_handlers[i][j].sync = 0;
 209                         irq_handlers[i][j].routine = NULL;
 210                         irq_handlers[i][j].data = NULL;
 211                 }
 212         }
 213 #endif
 214 }