/*
* System timer for CSR SiRFprimaII
*
* Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
*
* Licensed under GPLv2 or later.
*/
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/bitops.h>
#include <linux/irq.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <mach/map.h>
#include <asm/mach/time.h>
#define SIRFSOC_TIMER_COUNTER_LO 0x0000
#define SIRFSOC_TIMER_COUNTER_HI 0x0004
#define SIRFSOC_TIMER_MATCH_0 0x0008
#define SIRFSOC_TIMER_MATCH_1 0x000C
#define SIRFSOC_TIMER_MATCH_2 0x0010
#define SIRFSOC_TIMER_MATCH_3 0x0014
#define SIRFSOC_TIMER_MATCH_4 0x0018
#define SIRFSOC_TIMER_MATCH_5 0x001C
#define SIRFSOC_TIMER_STATUS 0x0020
#define SIRFSOC_TIMER_INT_EN 0x0024
#define SIRFSOC_TIMER_WATCHDOG_EN 0x0028
#define SIRFSOC_TIMER_DIV 0x002C
#define SIRFSOC_TIMER_LATCH 0x0030
#define SIRFSOC_TIMER_LATCHED_LO 0x0034
#define SIRFSOC_TIMER_LATCHED_HI 0x0038
#define SIRFSOC_TIMER_WDT_INDEX 5
#define SIRFSOC_TIMER_LATCH_BIT BIT(0)
static void __iomem *sirfsoc_timer_base;
static void __init sirfsoc_of_timer_map(void);
/* timer0 interrupt handler */
static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *ce = dev_id;
WARN_ON(!(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_STATUS) & BIT(0)));
/* clear timer0 interrupt */
writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
ce->event_handler(ce);
return IRQ_HANDLED;
}
/* read 64-bit timer counter */
static cycle_t sirfsoc_timer_read(struct clocksource *cs)
{
u64 cycles;
/* latch the 64-bit timer counter */
writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
cycles = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_HI);
cycles = (cycles << 32) | readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
return cycles;
}
static int sirfsoc_timer_set_next_event(unsigned long delta,
struct clock_event_device *ce)
{
unsigned long now, next;
writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
next = now + delta;
writel_relaxed(next, sirfsoc_timer_base + SIRFSOC_TIMER_MATCH_0);
writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
return next - now > delta ? -ETIME : 0;
}
static void sirfsoc_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *ce)
{
u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
WARN_ON(1);
break;
case CLOCK_EVT_MODE_ONESHOT:
writel_relaxed(val | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
writel_relaxed(val & ~BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
break;
}
}
static struct clock_event_device sirfsoc_clockevent = {
.name = "sirfsoc_clockevent",
.rating = 200,
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_mode = sirfsoc_timer_set_mode,
.set_next_event = sirfsoc_timer_set_next_event,
};
static struct clocksource sirfsoc_clocksource = {
.name = "sirfsoc_clocksource",
.rating = 200,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.read = sirfsoc_timer_read,
};
static struct irqaction sirfsoc_timer_irq = {
.name = "sirfsoc_timer0",
.flags = IRQF_TIMER,
.irq = 0,
.handler = sirfsoc_timer_interrupt,
.dev_id = &sirfsoc_clockevent,
};
/* Overwrite weak default sched_clock with more precise one */
unsigned long long notrace sched_clock(void)
{
static int is_mapped = 0;
/*
* sched_clock is called earlier than .init of sys_timer
* if we map timer memory in .init of sys_timer, system
* will panic due to illegal memory access
*/
if(!is_mapped) {
sirfsoc_of_timer_map();
is_mapped = 1;
}
return sirfsoc_timer_read(NULL) * (NSEC_PER_SEC / CLOCK_TICK_RATE);
}
static void __init sirfsoc_clockevent_init(void)
{
clockevents_calc_mult_shift(&sirfsoc_clockevent, CLOCK_TICK_RATE, 60);
sirfsoc_clockevent.max_delta_ns =
clockevent_delta2ns(-2, &sirfsoc_clockevent);
sirfsoc_clockevent.min_delta_ns =
clockevent_delta2ns(2, &sirfsoc_clockevent);
sirfsoc_clockevent.cpumask = cpumask_of(0);
clockevents_register_device(&sirfsoc_clockevent);
}
/* initialize the kernel jiffy timer source */
static void __init sirfsoc_timer_init(void)
{
unsigned long rate;
/* timer's input clock is io clock */
struct clk *clk = clk_get_sys("io", NULL);
BUG_ON(IS_ERR(clk));
rate = clk_get_rate(clk);
BUG_ON(rate < CLOCK_TICK_RATE);
BUG_ON(rate % CLOCK_TICK_RATE);
writel_relaxed(rate / CLOCK_TICK_RATE / 2 - 1, sirfsoc_timer_base + SIRFSOC_TIMER_DIV);
writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
BUG_ON(clocksource_register_hz(&sirfsoc_clocksource, CLOCK_TICK_RATE));
BUG_ON(setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq));
sirfsoc_clockevent_init();
}
static struct of_device_id timer_ids[] = {
{ .compatible = "sirf,prima2-tick" },
};
static void __init sirfsoc_of_timer_map(void)
{
struct device_node *np;
const unsigned int *intspec;
np = of_find_matching_node(NULL, timer_ids);
if (!np)
panic("unable to find compatible timer node in dtb\n");
sirfsoc_timer_base = of_iomap(np, 0);
if (!sirfsoc_timer_base)
panic("unable to map timer cpu registers\n");
/* Get the interrupts property */
intspec = of_get_property(np, "interrupts", NULL);
BUG_ON(!intspec);
sirfsoc_timer_irq.irq = be32_to_cpup(intspec);
of_node_put(np);
}
struct sys_timer sirfsoc_timer = {
.init = sirfsoc_timer_init,
};
