arch/mips/gt64120/common/time.c

   1 /*
   2  * This program is free software; you can redistribute  it and/or modify it
   3  * under  the terms of  the GNU General  Public License as published by the
   4  * Free Software Foundation;  either version 2 of the  License, or (at your
   5  * option) any later version.
   6  *
   7  * Galileo Technology chip interrupt handler
   8  */
   9 #include <linux/interrupt.h>
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/kernel_stat.h>
  13 #include <asm/irq_regs.h>
  14 #include <asm/gt64120.h>
  15
  16 /*
  17  * These are interrupt handlers for the GT on-chip interrupts.  They all come
  18  * in to the MIPS on a single interrupt line, and have to be handled and ack'ed
  19  * differently than other MIPS interrupts.
  20  */
  21
  22 static irqreturn_t gt64120_irq(int irq, void *dev_id)
  23 {
  24         unsigned int irq_src, int_high_src, irq_src_mask, int_high_src_mask;
  25         int handled = 0;
  26
  27         irq_src = GT_READ(GT_INTRCAUSE_OFS);
  28         irq_src_mask = GT_READ(GT_INTRMASK_OFS);
  29         int_high_src = GT_READ(GT_HINTRCAUSE_OFS);
  30         int_high_src_mask = GT_READ(GT_HINTRMASK_OFS);
  31         irq_src = irq_src & irq_src_mask;
  32         int_high_src = int_high_src & int_high_src_mask;
  33
  34         if (irq_src & 0x00000800) {     /* Check for timer interrupt */
  35                 handled = 1;
  36                 irq_src &= ~0x00000800;
  37                 do_timer(1);
  38 #ifndef CONFIG_SMP
  39                 update_process_times(user_mode(get_irq_regs()));
  40 #endif
  41         }
  42
  43         GT_WRITE(GT_INTRCAUSE_OFS, 0);
  44         GT_WRITE(GT_HINTRCAUSE_OFS, 0);
  45
  46         return IRQ_HANDLED;
  47 }
  48
  49 /*
  50  * Initializes timer using galileo's built in timer.
  51  */
  52 #ifdef CONFIG_SYSCLK_100
  53 #define Sys_clock (100 * 1000000)       // 100 MHz
  54 #endif
  55 #ifdef CONFIG_SYSCLK_83
  56 #define Sys_clock (83.333 * 1000000)    // 83.333 MHz
  57 #endif
  58 #ifdef CONFIG_SYSCLK_75
  59 #define Sys_clock (75 * 1000000)        // 75 MHz
  60 #endif
  61
  62 /*
  63  * This will ignore the standard MIPS timer interrupt handler that is passed in
  64  * as *irq (=irq0 in ../kernel/time.c).  We will do our own timer interrupt
  65  * handling.
  66  */
  67 void gt64120_time_init(void)
  68 {
  69         static struct irqaction timer;
  70
  71         /* Disable timer first */
  72         GT_WRITE(GT_TC_CONTROL_OFS, 0);
  73         /* Load timer value for 100 Hz */
  74         GT_WRITE(GT_TC3_OFS, Sys_clock / 100);
  75
  76         /*
  77          * Create the IRQ structure entry for the timer.  Since we're too early
  78          * in the boot process to use the "request_irq()" call, we'll hard-code
  79          * the values to the correct interrupt line.
  80          */
  81         timer.handler = gt64120_irq;
  82         timer.flags = IRQF_SHARED | IRQF_DISABLED;
  83         timer.name = "timer";
  84         timer.dev_id = NULL;
  85         timer.next = NULL;
  86         timer.mask = CPU_MASK_NONE;
  87         irq_desc[GT_TIMER].action = &timer;
  88
  89         enable_irq(GT_TIMER);
  90
  91         /* Enable timer ints */
  92         GT_WRITE(GT_TC_CONTROL_OFS, 0xc0);
  93         /* clear Cause register first */
  94         GT_WRITE(GT_INTRCAUSE_OFS, 0x0);
  95         /* Unmask timer int */
  96         GT_WRITE(GT_INTRMASK_OFS, 0x800);
  97         /* Clear High int register */
  98         GT_WRITE(GT_HINTRCAUSE_OFS, 0x0);
  99         /* Mask All interrupts at High cause interrupt */
 100         GT_WRITE(GT_HINTRMASK_OFS, 0x0);
 101 }