arch/mips/pnx8550/common/time.c

   1 /*
   2  * Copyright 2001, 2002, 2003 MontaVista Software Inc.
   3  * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
   4  * Copyright (C) 2007 Ralf Baechle (ralf@linux-mips.org)
   5  *
   6  * Common time service routines for MIPS machines. See
   7  * Documents/MIPS/README.txt.
   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/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/sched.h>
  18 #include <linux/param.h>
  19 #include <linux/time.h>
  20 #include <linux/timer.h>
  21 #include <linux/smp.h>
  22 #include <linux/kernel_stat.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/interrupt.h>
  25
  26 #include <asm/bootinfo.h>
  27 #include <asm/cpu.h>
  28 #include <asm/time.h>
  29 #include <asm/hardirq.h>
  30 #include <asm/div64.h>
  31 #include <asm/debug.h>
  32
  33 #include <int.h>
  34 #include <cm.h>
  35
  36 static unsigned long cpj;
  37
  38 static cycle_t hpt_read(struct clocksource *cs)
  39 {
  40         return read_c0_count2();
  41 }
  42
  43 static struct clocksource pnx_clocksource = {
  44         .name           = "pnx8xxx",
  45         .rating         = 200,
  46         .read           = hpt_read,
  47         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  48 };
  49
  50 static irqreturn_t pnx8xxx_timer_interrupt(int irq, void *dev_id)
  51 {
  52         struct clock_event_device *c = dev_id;
  53
  54         /* clear MATCH, signal the event */
  55         c->event_handler(c);
  56
  57         return IRQ_HANDLED;
  58 }
  59
  60 static struct irqaction pnx8xxx_timer_irq = {
  61         .handler        = pnx8xxx_timer_interrupt,
  62         .flags          = IRQF_PERCPU | IRQF_TIMER,
  63         .name           = "pnx8xxx_timer",
  64 };
  65
  66 static irqreturn_t monotonic_interrupt(int irq, void *dev_id)
  67 {
  68         /* Timer 2 clear interrupt */
  69         write_c0_compare2(-1);
  70         return IRQ_HANDLED;
  71 }
  72
  73 static struct irqaction monotonic_irqaction = {
  74         .handler = monotonic_interrupt,
  75         .flags = IRQF_TIMER,
  76         .name = "Monotonic timer",
  77 };
  78
  79 static int pnx8xxx_set_next_event(unsigned long delta,
  80                                 struct clock_event_device *evt)
  81 {
  82         write_c0_compare(delta);
  83         return 0;
  84 }
  85
  86 static struct clock_event_device pnx8xxx_clockevent = {
  87         .name           = "pnx8xxx_clockevent",
  88         .features       = CLOCK_EVT_FEAT_ONESHOT,
  89         .set_next_event = pnx8xxx_set_next_event,
  90 };
  91
  92 static inline void timer_ack(void)
  93 {
  94         write_c0_compare(cpj);
  95 }
  96
  97 __init void plat_time_init(void)
  98 {
  99         unsigned int configPR;
 100         unsigned int n;
 101         unsigned int m;
 102         unsigned int p;
 103         unsigned int pow2p;
 104
 105         pnx8xxx_clockevent.cpumask = cpu_none_mask;
 106         clockevents_register_device(&pnx8xxx_clockevent);
 107         clocksource_register(&pnx_clocksource);
 108
 109         /* Timer 1 start */
 110         configPR = read_c0_config7();
 111         configPR &= ~0x00000008;
 112         write_c0_config7(configPR);
 113
 114         /* Timer 2 start */
 115         configPR = read_c0_config7();
 116         configPR &= ~0x00000010;
 117         write_c0_config7(configPR);
 118
 119         /* Timer 3 stop */
 120         configPR = read_c0_config7();
 121         configPR |= 0x00000020;
 122         write_c0_config7(configPR);
 123
 124
 125         /* PLL0 sets MIPS clock (PLL1 <=> TM1, PLL6 <=> TM2, PLL5 <=> mem) */
 126         /* (but only if CLK_MIPS_CTL select value [bits 3:1] is 1:  FIXME) */
 127
 128         n = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_N_MASK) >> 16;
 129         m = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_M_MASK) >> 8;
 130         p = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_P_MASK) >> 2;
 131         pow2p = (1 << p);
 132
 133         db_assert(m != 0 && pow2p != 0);
 134
 135         /*
 136          * Compute the frequency as in the PNX8550 User Manual 1.0, p.186
 137          * (a.k.a. 8-10).  Divide by HZ for a timer offset that results in
 138          * HZ timer interrupts per second.
 139          */
 140         mips_hpt_frequency = 27UL * ((1000000UL * n)/(m * pow2p));
 141         cpj = DIV_ROUND_CLOSEST(mips_hpt_frequency, HZ);
 142         write_c0_count(0);
 143         timer_ack();
 144
 145         /* Setup Timer 2 */
 146         write_c0_count2(0);
 147         write_c0_compare2(0xffffffff);
 148
 149         setup_irq(PNX8550_INT_TIMER1, &pnx8xxx_timer_irq);
 150         setup_irq(PNX8550_INT_TIMER2, &monotonic_irqaction);
 151 }