/*
* arch/arm/plat-orion/time.c
*
* Marvell Orion SoC timer handling.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* Timer 0 is used as free-running clocksource, while timer 1 is
* used as clock_event_device.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cnt32_to_63.h>
#include <linux/timer.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/mach/time.h>
#include <mach/bridge-regs.h>
#include <mach/hardware.h>
/*
* Number of timer ticks per jiffy.
*/
static u32 ticks_per_jiffy;
/*
* Timer block registers.
*/
#define TIMER_CTRL (TIMER_VIRT_BASE + 0x0000)
#define TIMER0_EN 0x0001
#define TIMER0_RELOAD_EN 0x0002
#define TIMER1_EN 0x0004
#define TIMER1_RELOAD_EN 0x0008
#define TIMER0_RELOAD (TIMER_VIRT_BASE + 0x0010)
#define TIMER0_VAL (TIMER_VIRT_BASE + 0x0014)
#define TIMER1_RELOAD (TIMER_VIRT_BASE + 0x0018)
#define TIMER1_VAL (TIMER_VIRT_BASE + 0x001c)
/*
* Orion's sched_clock implementation. It has a resolution of
* at least 7.5ns (133MHz TCLK) and a maximum value of 834 days.
*
* Because the hardware timer period is quite short (21 secs if
* 200MHz TCLK) and because cnt32_to_63() needs to be called at
* least once per half period to work properly, a kernel timer is
* set up to ensure this requirement is always met.
*/
#define TCLK2NS_SCALE_FACTOR 8
static unsigned long tclk2ns_scale;
unsigned long long notrace sched_clock(void)
{
unsigned long long v = cnt32_to_63(0xffffffff - readl(TIMER0_VAL));
return (v * tclk2ns_scale) >> TCLK2NS_SCALE_FACTOR;
}
static struct timer_list cnt32_to_63_keepwarm_timer;
static void cnt32_to_63_keepwarm(unsigned long data)
{
mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
(void) sched_clock();
}
static void __init setup_sched_clock(unsigned long tclk)
{
unsigned long long v;
unsigned long data;
v = NSEC_PER_SEC;
v <<= TCLK2NS_SCALE_FACTOR;
v += tclk/2;
do_div(v, tclk);
/*
* We want an even value to automatically clear the top bit
* returned by cnt32_to_63() without an additional run time
* instruction. So if the LSB is 1 then round it up.
*/
if (v & 1)
v++;
tclk2ns_scale = v;
data = (0xffffffffUL / tclk / 2 - 2) * HZ;
setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
}
/*
* Clocksource handling.
*/
static cycle_t orion_clksrc_read(struct clocksource *cs)
{
return 0xffffffff - readl(TIMER0_VAL);
}
static struct clocksource orion_clksrc = {
.name = "orion_clocksource",
.rating = 300,
.read = orion_clksrc_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Clockevent handling.
*/
static int
orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
{
unsigned long flags;
u32 u;
if (delta == 0)
return -ETIME;
local_irq_save(flags);
/*
* Clear and enable clockevent timer interrupt.
*/
writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
u = readl(BRIDGE_MASK);
u |= BRIDGE_INT_TIMER1;
writel(u, BRIDGE_MASK);
/*
* Setup new clockevent timer value.
*/
writel(delta, TIMER1_VAL);
/*
* Enable the timer.
*/
u = readl(TIMER_CTRL);
u = (u & ~TIMER1_RELOAD_EN) | TIMER1_EN;
writel(u, TIMER_CTRL);
local_irq_restore(flags);
return 0;
}
static void
orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
{
unsigned long flags;
u32 u;
local_irq_save(flags);
if (mode == CLOCK_EVT_MODE_PERIODIC) {
/*
* Setup timer to fire at 1/HZ intervals.
*/
writel(ticks_per_jiffy - 1, TIMER1_RELOAD);
writel(ticks_per_jiffy - 1, TIMER1_VAL);
/*
* Enable timer interrupt.
*/
u = readl(BRIDGE_MASK);
writel(u | BRIDGE_INT_TIMER1, BRIDGE_MASK);
/*
* Enable timer.
*/
u = readl(TIMER_CTRL);
writel(u | TIMER1_EN | TIMER1_RELOAD_EN, TIMER_CTRL);
} else {
/*
* Disable timer.
*/
u = readl(TIMER_CTRL);
writel(u & ~TIMER1_EN, TIMER_CTRL);
/*
* Disable timer interrupt.
*/
u = readl(BRIDGE_MASK);
writel(u & ~BRIDGE_INT_TIMER1, BRIDGE_MASK);
/*
* ACK pending timer interrupt.
*/
writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
}
local_irq_restore(flags);
}
static struct clock_event_device orion_clkevt = {
.name = "orion_tick",
.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
.shift = 32,
.rating = 300,
.set_next_event = orion_clkevt_next_event,
.set_mode = orion_clkevt_mode,
};
static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
{
/*
* ACK timer interrupt and call event handler.
*/
writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
orion_clkevt.event_handler(&orion_clkevt);
return IRQ_HANDLED;
}
static struct irqaction orion_timer_irq = {
.name = "orion_tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = orion_timer_interrupt
};
void __init orion_time_init(unsigned int irq, unsigned int tclk)
{
u32 u;
ticks_per_jiffy = (tclk + HZ/2) / HZ;
/*
* Set scale and timer for sched_clock
*/
setup_sched_clock(tclk);
/*
* Setup free-running clocksource timer (interrupts
* disabled.)
*/
writel(0xffffffff, TIMER0_VAL);
writel(0xffffffff, TIMER0_RELOAD);
u = readl(BRIDGE_MASK);
writel(u & ~BRIDGE_INT_TIMER0, BRIDGE_MASK);
u = readl(TIMER_CTRL);
writel(u | TIMER0_EN | TIMER0_RELOAD_EN, TIMER_CTRL);
clocksource_register_hz(&orion_clksrc, tclk);
/*
* Setup clockevent timer (interrupt-driven.)
*/
setup_irq(irq, &orion_timer_irq);
orion_clkevt.mult = div_sc(tclk, NSEC_PER_SEC, orion_clkevt.shift);
orion_clkevt.max_delta_ns = clockevent_delta2ns(0xfffffffe, &orion_clkevt);
orion_clkevt.min_delta_ns = clockevent_delta2ns(1, &orion_clkevt);
orion_clkevt.cpumask = cpumask_of(0);
clockevents_register_device(&orion_clkevt);
}
