time.c
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/*
* Copyright (C) 2001-2006 Storlink, Corp.
* Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
*
* This program 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.
*/
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <mach/global_reg.h>
#include <asm/mach/time.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
/*
* Register definitions for the timers
*/
#define TIMER_COUNT(BASE_ADDR) (BASE_ADDR + 0x00)
#define TIMER_LOAD(BASE_ADDR) (BASE_ADDR + 0x04)
#define TIMER_MATCH1(BASE_ADDR) (BASE_ADDR + 0x08)
#define TIMER_MATCH2(BASE_ADDR) (BASE_ADDR + 0x0C)
#define TIMER_CR(BASE_ADDR) (BASE_ADDR + 0x30)
#define TIMER_1_CR_ENABLE (1 << 0)
#define TIMER_1_CR_CLOCK (1 << 1)
#define TIMER_1_CR_INT (1 << 2)
#define TIMER_2_CR_ENABLE (1 << 3)
#define TIMER_2_CR_CLOCK (1 << 4)
#define TIMER_2_CR_INT (1 << 5)
#define TIMER_3_CR_ENABLE (1 << 6)
#define TIMER_3_CR_CLOCK (1 << 7)
#define TIMER_3_CR_INT (1 << 8)
static unsigned int tick_rate;
static int gemini_timer_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
u32 cr;
cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
/* This may be overdoing it, feel free to test without this */
cr &= ~TIMER_2_CR_ENABLE;
cr &= ~TIMER_2_CR_INT;
writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
/* Set next event */
writel(cycles, TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER2_BASE)));
writel(cycles, TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER2_BASE)));
cr |= TIMER_2_CR_ENABLE;
cr |= TIMER_2_CR_INT;
writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
return 0;
}
static void gemini_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
u32 period = DIV_ROUND_CLOSEST(tick_rate, HZ);
u32 cr;
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
/* Start the timer */
writel(period,
TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER2_BASE)));
writel(period,
TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER2_BASE)));
cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
cr |= TIMER_2_CR_ENABLE;
cr |= TIMER_2_CR_INT;
writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
break;
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_RESUME:
/*
* Disable also for oneshot: the set_next() call will
* arm the timer instead.
*/
cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
cr &= ~TIMER_2_CR_ENABLE;
cr &= ~TIMER_2_CR_INT;
writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
break;
default:
break;
}
}
/* Use TIMER2 as clock event */
static struct clock_event_device gemini_clockevent = {
.name = "TIMER2",
.rating = 300, /* Reasonably fast and accurate clock event */
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = gemini_timer_set_next_event,
.set_mode = gemini_timer_set_mode,
};
/*
* IRQ handler for the timer
*/
static irqreturn_t gemini_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &gemini_clockevent;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction gemini_timer_irq = {
.name = "Gemini Timer Tick",
.flags = IRQF_TIMER,
.handler = gemini_timer_interrupt,
};
/*
* Set up timer interrupt, and return the current time in seconds.
*/
void __init gemini_timer_init(void)
{
u32 reg_v;
reg_v = readl(IO_ADDRESS(GEMINI_GLOBAL_BASE + GLOBAL_STATUS));
tick_rate = REG_TO_AHB_SPEED(reg_v) * 1000000;
printk(KERN_INFO "Bus: %dMHz", tick_rate / 1000000);
tick_rate /= 6; /* APB bus run AHB*(1/6) */
switch(reg_v & CPU_AHB_RATIO_MASK) {
case CPU_AHB_1_1:
printk(KERN_CONT "(1/1)\n");
break;
case CPU_AHB_3_2:
printk(KERN_CONT "(3/2)\n");
break;
case CPU_AHB_24_13:
printk(KERN_CONT "(24/13)\n");
break;
case CPU_AHB_2_1:
printk(KERN_CONT "(2/1)\n");
break;
}
/*
* Make irqs happen for the system timer
*/
setup_irq(IRQ_TIMER2, &gemini_timer_irq);
/* Enable and use TIMER1 as clock source */
writel(0xffffffff, TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER1_BASE)));
writel(0xffffffff, TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER1_BASE)));
writel(TIMER_1_CR_ENABLE, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
if (clocksource_mmio_init(TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER1_BASE)),
"TIMER1", tick_rate, 300, 32,
clocksource_mmio_readl_up))
pr_err("timer: failed to initialize gemini clock source\n");
/* Configure and register the clockevent */
clockevents_config_and_register(&gemini_clockevent, tick_rate,
1, 0xffffffff);
}