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/*
* Copyright (C) 2004-2007 Atmel Corporation
*
* Based on MIPS implementation arch/mips/kernel/time.c
* Copyright 2001 MontaVista Software Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel_stat.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/sysdev.h>
#include <linux/err.h>
#include <asm/div64.h>
#include <asm/sysreg.h>
#include <asm/io.h>
#include <asm/sections.h>
#include <asm/arch/time.h>
/* how many counter cycles in a jiffy? */
static u32 cycles_per_jiffy;
/* the count value for the next timer interrupt */
static u32 expirelo;
/* the I/O registers of the TC module */
static void __iomem *ioregs;
cycle_t read_cycle_count(void)
{
return (cycle_t)timer_read(ioregs, 0, CV);
}
struct clocksource clocksource_avr32 = {
.name = "avr32",
.rating = 342,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(16),
.shift = 16,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void avr32_timer_ack(void)
{
u16 count = expirelo;
/* Ack this timer interrupt and set the next one, use a u16
* variable so it will wrap around correctly */
count += cycles_per_jiffy;
expirelo = count;
timer_write(ioregs, 0, RC, expirelo);
/* Check to see if we have missed any timer interrupts */
count = timer_read(ioregs, 0, CV);
if ((count - expirelo) < 0x7fff) {
expirelo = count + cycles_per_jiffy;
timer_write(ioregs, 0, RC, expirelo);
}
}
u32 avr32_hpt_read(void)
{
return timer_read(ioregs, 0, CV);
}
static int avr32_timer_calc_div_and_set_jiffies(struct clk *pclk)
{
unsigned int cycles_max = (clocksource_avr32.mask + 1) / 2;
unsigned int divs[] = { 4, 8, 16, 32 };
int divs_size = sizeof(divs) / sizeof(*divs);
int i = 0;
unsigned long count_hz;
unsigned long shift;
unsigned long mult;
int clock_div = -1;
u64 tmp;
shift = clocksource_avr32.shift;
do {
count_hz = clk_get_rate(pclk) / divs[i];
mult = clocksource_hz2mult(count_hz, shift);
clocksource_avr32.mult = mult;
tmp = TICK_NSEC;
tmp <<= shift;
tmp += mult / 2;
do_div(tmp, mult);
cycles_per_jiffy = tmp;
} while (cycles_per_jiffy > cycles_max && ++i < divs_size);
clock_div = i + 1;
if (clock_div > divs_size) {
pr_debug("timer: could not calculate clock divider\n");
return -EFAULT;
}
/* Set the clock divider */
timer_write(ioregs, 0, CMR, TIMER_BF(CMR_TCCLKS, clock_div));
return 0;
}
int avr32_hpt_init(unsigned int count)
{
struct resource *regs;
struct clk *pclk;
int irq = -1;
int ret = 0;
ret = -ENXIO;
irq = platform_get_irq(&at32_systc0_device, 0);
if (irq < 0) {
pr_debug("timer: could not get irq\n");
goto out_error;
}
pclk = clk_get(&at32_systc0_device.dev, "pclk");
if (IS_ERR(pclk)) {
pr_debug("timer: could not get clk: %ld\n", PTR_ERR(pclk));
goto out_error;
}
clk_enable(pclk);
regs = platform_get_resource(&at32_systc0_device, IORESOURCE_MEM, 0);
if (!regs) {
pr_debug("timer: could not get resource\n");
goto out_error_clk;
}
ioregs = ioremap(regs->start, regs->end - regs->start + 1);
if (!ioregs) {
pr_debug("timer: could not get ioregs\n");
goto out_error_clk;
}
ret = avr32_timer_calc_div_and_set_jiffies(pclk);
if (ret)
goto out_error_io;
ret = setup_irq(irq, &timer_irqaction);
if (ret) {
pr_debug("timer: could not request irq %d: %d\n",
irq, ret);
goto out_error_io;
}
expirelo = (timer_read(ioregs, 0, CV) / cycles_per_jiffy + 1)
* cycles_per_jiffy;
/* Enable clock and interrupts on RC compare */
timer_write(ioregs, 0, CCR, TIMER_BIT(CCR_CLKEN));
timer_write(ioregs, 0, IER, TIMER_BIT(IER_CPCS));
/* Set cycles to first interrupt */
timer_write(ioregs, 0, RC, expirelo);
printk(KERN_INFO "timer: AT32AP system timer/counter at 0x%p irq %d\n",
ioregs, irq);
return 0;
out_error_io:
iounmap(ioregs);
out_error_clk:
clk_put(pclk);
out_error:
return ret;
}
int avr32_hpt_start(void)
{
timer_write(ioregs, 0, CCR, TIMER_BIT(CCR_SWTRG));
return 0;
}
irqreturn_t timer_interrupt(int irq, void *dev_id)
{
unsigned int sr = timer_read(ioregs, 0, SR);
if (sr & TIMER_BIT(SR_CPCS)) {
/* ack timer interrupt and try to set next interrupt */
avr32_timer_ack();
/*
* Call the generic timer interrupt handler
*/
write_seqlock(&xtime_lock);
do_timer(1);
write_sequnlock(&xtime_lock);
/*
* In UP mode, we call local_timer_interrupt() to do profiling
* and process accounting.
*
* SMP is not supported yet.
*/
local_timer_interrupt(irq, dev_id);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
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