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linux/arch/arm/mach-u300/timer.c
Linus Walleij a2ca00ea93 ARM: 5704/1: U300 sched_clock implementation v2 
This adds the long debated sched_clock() override for the weak
in-kernel jiffybased sched_clock(). The implementation is more or
less identical to the one used in arch/arm/plat-omap/common.c
and at last attempt to merge this the merge was postponed at the
request of Peter Zijlstra due to pending discussions regarding
generalized clocksource-based sched_clock() implementations by
adding a flag to the clocksource. However that discussion ended
up with the generic code needing to be rewritten and Paul Mundt
see no reason not to proceed with this for the time being as it
can be easily converted once the generic code is in place.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-09-18 22:09:02 +01:00

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/*
*
* arch/arm/mach-u300/timer.c
*
*
* Copyright (C) 2007-2009 ST-Ericsson AB
* License terms: GNU General Public License (GPL) version 2
* Timer COH 901 328, runs the OS timer interrupt.
* Author: Linus Walleij <linus.walleij@stericsson.com>
*/
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/types.h>
#include <linux/io.h>
#include <mach/hardware.h>
/* Generic stuff */
#include <asm/mach/map.h>
#include <asm/mach/time.h>
#include <asm/mach/irq.h>
#include "clock.h"
/*
* APP side special timer registers
* This timer contains four timers which can fire an interrupt each.
* OS (operating system) timer @ 32768 Hz
* DD (device driver) timer @ 1 kHz
* GP1 (general purpose 1) timer @ 1MHz
* GP2 (general purpose 2) timer @ 1MHz
*/
/* Reset OS Timer 32bit (-/W) */
#define U300_TIMER_APP_ROST (0x0000)
#define U300_TIMER_APP_ROST_TIMER_RESET (0x00000000)
/* Enable OS Timer 32bit (-/W) */
#define U300_TIMER_APP_EOST (0x0004)
#define U300_TIMER_APP_EOST_TIMER_ENABLE (0x00000000)
/* Disable OS Timer 32bit (-/W) */
#define U300_TIMER_APP_DOST (0x0008)
#define U300_TIMER_APP_DOST_TIMER_DISABLE (0x00000000)
/* OS Timer Mode Register 32bit (-/W) */
#define U300_TIMER_APP_SOSTM (0x000c)
#define U300_TIMER_APP_SOSTM_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_SOSTM_MODE_ONE_SHOT (0x00000001)
/* OS Timer Status Register 32bit (R/-) */
#define U300_TIMER_APP_OSTS (0x0010)
#define U300_TIMER_APP_OSTS_TIMER_STATE_MASK (0x0000000F)
#define U300_TIMER_APP_OSTS_TIMER_STATE_IDLE (0x00000001)
#define U300_TIMER_APP_OSTS_TIMER_STATE_ACTIVE (0x00000002)
#define U300_TIMER_APP_OSTS_ENABLE_IND (0x00000010)
#define U300_TIMER_APP_OSTS_MODE_MASK (0x00000020)
#define U300_TIMER_APP_OSTS_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_OSTS_MODE_ONE_SHOT (0x00000020)
#define U300_TIMER_APP_OSTS_IRQ_ENABLED_IND (0x00000040)
#define U300_TIMER_APP_OSTS_IRQ_PENDING_IND (0x00000080)
/* OS Timer Current Count Register 32bit (R/-) */
#define U300_TIMER_APP_OSTCC (0x0014)
/* OS Timer Terminal Count Register 32bit (R/W) */
#define U300_TIMER_APP_OSTTC (0x0018)
/* OS Timer Interrupt Enable Register 32bit (-/W) */
#define U300_TIMER_APP_OSTIE (0x001c)
#define U300_TIMER_APP_OSTIE_IRQ_DISABLE (0x00000000)
#define U300_TIMER_APP_OSTIE_IRQ_ENABLE (0x00000001)
/* OS Timer Interrupt Acknowledge Register 32bit (-/W) */
#define U300_TIMER_APP_OSTIA (0x0020)
#define U300_TIMER_APP_OSTIA_IRQ_ACK (0x00000080)
/* Reset DD Timer 32bit (-/W) */
#define U300_TIMER_APP_RDDT (0x0040)
#define U300_TIMER_APP_RDDT_TIMER_RESET (0x00000000)
/* Enable DD Timer 32bit (-/W) */
#define U300_TIMER_APP_EDDT (0x0044)
#define U300_TIMER_APP_EDDT_TIMER_ENABLE (0x00000000)
/* Disable DD Timer 32bit (-/W) */
#define U300_TIMER_APP_DDDT (0x0048)
#define U300_TIMER_APP_DDDT_TIMER_DISABLE (0x00000000)
/* DD Timer Mode Register 32bit (-/W) */
#define U300_TIMER_APP_SDDTM (0x004c)
#define U300_TIMER_APP_SDDTM_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_SDDTM_MODE_ONE_SHOT (0x00000001)
/* DD Timer Status Register 32bit (R/-) */
#define U300_TIMER_APP_DDTS (0x0050)
#define U300_TIMER_APP_DDTS_TIMER_STATE_MASK (0x0000000F)
#define U300_TIMER_APP_DDTS_TIMER_STATE_IDLE (0x00000001)
#define U300_TIMER_APP_DDTS_TIMER_STATE_ACTIVE (0x00000002)
#define U300_TIMER_APP_DDTS_ENABLE_IND (0x00000010)
#define U300_TIMER_APP_DDTS_MODE_MASK (0x00000020)
#define U300_TIMER_APP_DDTS_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_DDTS_MODE_ONE_SHOT (0x00000020)
#define U300_TIMER_APP_DDTS_IRQ_ENABLED_IND (0x00000040)
#define U300_TIMER_APP_DDTS_IRQ_PENDING_IND (0x00000080)
/* DD Timer Current Count Register 32bit (R/-) */
#define U300_TIMER_APP_DDTCC (0x0054)
/* DD Timer Terminal Count Register 32bit (R/W) */
#define U300_TIMER_APP_DDTTC (0x0058)
/* DD Timer Interrupt Enable Register 32bit (-/W) */
#define U300_TIMER_APP_DDTIE (0x005c)
#define U300_TIMER_APP_DDTIE_IRQ_DISABLE (0x00000000)
#define U300_TIMER_APP_DDTIE_IRQ_ENABLE (0x00000001)
/* DD Timer Interrupt Acknowledge Register 32bit (-/W) */
#define U300_TIMER_APP_DDTIA (0x0060)
#define U300_TIMER_APP_DDTIA_IRQ_ACK (0x00000080)
/* Reset GP1 Timer 32bit (-/W) */
#define U300_TIMER_APP_RGPT1 (0x0080)
#define U300_TIMER_APP_RGPT1_TIMER_RESET (0x00000000)
/* Enable GP1 Timer 32bit (-/W) */
#define U300_TIMER_APP_EGPT1 (0x0084)
#define U300_TIMER_APP_EGPT1_TIMER_ENABLE (0x00000000)
/* Disable GP1 Timer 32bit (-/W) */
#define U300_TIMER_APP_DGPT1 (0x0088)
#define U300_TIMER_APP_DGPT1_TIMER_DISABLE (0x00000000)
/* GP1 Timer Mode Register 32bit (-/W) */
#define U300_TIMER_APP_SGPT1M (0x008c)
#define U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT (0x00000001)
/* GP1 Timer Status Register 32bit (R/-) */
#define U300_TIMER_APP_GPT1S (0x0090)
#define U300_TIMER_APP_GPT1S_TIMER_STATE_MASK (0x0000000F)
#define U300_TIMER_APP_GPT1S_TIMER_STATE_IDLE (0x00000001)
#define U300_TIMER_APP_GPT1S_TIMER_STATE_ACTIVE (0x00000002)
#define U300_TIMER_APP_GPT1S_ENABLE_IND (0x00000010)
#define U300_TIMER_APP_GPT1S_MODE_MASK (0x00000020)
#define U300_TIMER_APP_GPT1S_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_GPT1S_MODE_ONE_SHOT (0x00000020)
#define U300_TIMER_APP_GPT1S_IRQ_ENABLED_IND (0x00000040)
#define U300_TIMER_APP_GPT1S_IRQ_PENDING_IND (0x00000080)
/* GP1 Timer Current Count Register 32bit (R/-) */
#define U300_TIMER_APP_GPT1CC (0x0094)
/* GP1 Timer Terminal Count Register 32bit (R/W) */
#define U300_TIMER_APP_GPT1TC (0x0098)
/* GP1 Timer Interrupt Enable Register 32bit (-/W) */
#define U300_TIMER_APP_GPT1IE (0x009c)
#define U300_TIMER_APP_GPT1IE_IRQ_DISABLE (0x00000000)
#define U300_TIMER_APP_GPT1IE_IRQ_ENABLE (0x00000001)
/* GP1 Timer Interrupt Acknowledge Register 32bit (-/W) */
#define U300_TIMER_APP_GPT1IA (0x00a0)
#define U300_TIMER_APP_GPT1IA_IRQ_ACK (0x00000080)
/* Reset GP2 Timer 32bit (-/W) */
#define U300_TIMER_APP_RGPT2 (0x00c0)
#define U300_TIMER_APP_RGPT2_TIMER_RESET (0x00000000)
/* Enable GP2 Timer 32bit (-/W) */
#define U300_TIMER_APP_EGPT2 (0x00c4)
#define U300_TIMER_APP_EGPT2_TIMER_ENABLE (0x00000000)
/* Disable GP2 Timer 32bit (-/W) */
#define U300_TIMER_APP_DGPT2 (0x00c8)
#define U300_TIMER_APP_DGPT2_TIMER_DISABLE (0x00000000)
/* GP2 Timer Mode Register 32bit (-/W) */
#define U300_TIMER_APP_SGPT2M (0x00cc)
#define U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_SGPT2M_MODE_ONE_SHOT (0x00000001)
/* GP2 Timer Status Register 32bit (R/-) */
#define U300_TIMER_APP_GPT2S (0x00d0)
#define U300_TIMER_APP_GPT2S_TIMER_STATE_MASK (0x0000000F)
#define U300_TIMER_APP_GPT2S_TIMER_STATE_IDLE (0x00000001)
#define U300_TIMER_APP_GPT2S_TIMER_STATE_ACTIVE (0x00000002)
#define U300_TIMER_APP_GPT2S_ENABLE_IND (0x00000010)
#define U300_TIMER_APP_GPT2S_MODE_MASK (0x00000020)
#define U300_TIMER_APP_GPT2S_MODE_CONTINUOUS (0x00000000)
#define U300_TIMER_APP_GPT2S_MODE_ONE_SHOT (0x00000020)
#define U300_TIMER_APP_GPT2S_IRQ_ENABLED_IND (0x00000040)
#define U300_TIMER_APP_GPT2S_IRQ_PENDING_IND (0x00000080)
/* GP2 Timer Current Count Register 32bit (R/-) */
#define U300_TIMER_APP_GPT2CC (0x00d4)
/* GP2 Timer Terminal Count Register 32bit (R/W) */
#define U300_TIMER_APP_GPT2TC (0x00d8)
/* GP2 Timer Interrupt Enable Register 32bit (-/W) */
#define U300_TIMER_APP_GPT2IE (0x00dc)
#define U300_TIMER_APP_GPT2IE_IRQ_DISABLE (0x00000000)
#define U300_TIMER_APP_GPT2IE_IRQ_ENABLE (0x00000001)
/* GP2 Timer Interrupt Acknowledge Register 32bit (-/W) */
#define U300_TIMER_APP_GPT2IA (0x00e0)
#define U300_TIMER_APP_GPT2IA_IRQ_ACK (0x00000080)
/* Clock request control register - all four timers */
#define U300_TIMER_APP_CRC (0x100)
#define U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE (0x00000001)
#define TICKS_PER_JIFFY ((CLOCK_TICK_RATE + (HZ/2)) / HZ)
#define US_PER_TICK ((1000000 + (HZ/2)) / HZ)
/*
* The u300_set_mode() function is always called first, if we
* have oneshot timer active, the oneshot scheduling function
* u300_set_next_event() is called immediately after.
*/
static void u300_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
/* Disable interrupts on GPT1 */
writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Disable GP1 while we're reprogramming it. */
writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DGPT1);
/*
* Set the periodic mode to a certain number of ticks per
* jiffy.
*/
writel(TICKS_PER_JIFFY,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1TC);
/*
* Set continuous mode, so the timer keeps triggering
* interrupts.
*/
writel(U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS,
U300_TIMER_APP_VBASE + U300_TIMER_APP_SGPT1M);
/* Enable timer interrupts */
writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Then enable the OS timer again */
writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_EGPT1);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* Just break; here? */
/*
* The actual event will be programmed by the next event hook,
* so we just set a dummy value somewhere at the end of the
* universe here.
*/
/* Disable interrupts on GPT1 */
writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Disable GP1 while we're reprogramming it. */
writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DGPT1);
/*
* Expire far in the future, u300_set_next_event() will be
* called soon...
*/
writel(0xFFFFFFFF, U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1TC);
/* We run one shot per tick here! */
writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
U300_TIMER_APP_VBASE + U300_TIMER_APP_SGPT1M);
/* Enable interrupts for this timer */
writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Enable timer */
writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_EGPT1);
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
/* Disable interrupts on GP1 */
writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Disable GP1 */
writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DGPT1);
break;
case CLOCK_EVT_MODE_RESUME:
/* Ignore this call */
break;
}
}
/*
* The app timer in one shot mode obviously has to be reprogrammed
* in EXACTLY this sequence to work properly. Do NOT try to e.g. replace
* the interrupt disable + timer disable commands with a reset command,
* it will fail miserably. Apparently (and I found this the hard way)
* the timer is very sensitive to the instruction order, though you don't
* get that impression from the data sheet.
*/
static int u300_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
/* Disable interrupts on GPT1 */
writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Disable GP1 while we're reprogramming it. */
writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DGPT1);
/* Reset the General Purpose timer 1. */
writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
U300_TIMER_APP_VBASE + U300_TIMER_APP_RGPT1);
/* IRQ in n * cycles */
writel(cycles, U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1TC);
/*
* We run one shot per tick here! (This is necessary to reconfigure,
* the timer will tilt if you don't!)
*/
writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
U300_TIMER_APP_VBASE + U300_TIMER_APP_SGPT1M);
/* Enable timer interrupts */
writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IE);
/* Then enable the OS timer again */
writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_EGPT1);
return 0;
}
/* Use general purpose timer 1 as clock event */
static struct clock_event_device clockevent_u300_1mhz = {
.name = "GPT1",
.rating = 300, /* Reasonably fast and accurate clock event */
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
/* 22 calculated using the algorithm in arch/mips/kernel/time.c */
.shift = 22,
.set_next_event = u300_set_next_event,
.set_mode = u300_set_mode,
};
/* Clock event timer interrupt handler */
static irqreturn_t u300_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_u300_1mhz;
/* ACK/Clear timer IRQ for the APP GPT1 Timer */
writel(U300_TIMER_APP_GPT1IA_IRQ_ACK,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT1IA);
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction u300_timer_irq = {
.name = "U300 Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = u300_timer_interrupt,
};
/* Use general purpose timer 2 as clock source */
static cycle_t u300_get_cycles(struct clocksource *cs)
{
return (cycles_t) readl(U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT2CC);
}
static struct clocksource clocksource_u300_1mhz = {
.name = "GPT2",
.rating = 300, /* Reasonably fast and accurate clock source */
.read = u300_get_cycles,
.mask = CLOCKSOURCE_MASK(32), /* 32 bits */
/* 22 calculated using the algorithm in arch/mips/kernel/time.c */
.shift = 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Override the global weak sched_clock symbol with this
* local implementation which uses the clocksource to get some
* better resolution when scheduling the kernel. We accept that
* this wraps around for now, since it is just a relative time
* stamp. (Inspired by OMAP implementation.)
*/
unsigned long long notrace sched_clock(void)
{
return clocksource_cyc2ns(clocksource_u300_1mhz.read(
&clocksource_u300_1mhz),
clocksource_u300_1mhz.mult,
clocksource_u300_1mhz.shift);
}
/*
* This sets up the system timers, clock source and clock event.
*/
static void __init u300_timer_init(void)
{
u300_enable_timer_clock();
/*
* Disable the "OS" and "DD" timers - these are designed for Symbian!
* Example usage in cnh1601578 cpu subsystem pd_timer_app.c
*/
writel(U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_CRC);
writel(U300_TIMER_APP_ROST_TIMER_RESET,
U300_TIMER_APP_VBASE + U300_TIMER_APP_ROST);
writel(U300_TIMER_APP_DOST_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DOST);
writel(U300_TIMER_APP_RDDT_TIMER_RESET,
U300_TIMER_APP_VBASE + U300_TIMER_APP_RDDT);
writel(U300_TIMER_APP_DDDT_TIMER_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_DDDT);
/* Reset the General Purpose timer 1. */
writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
U300_TIMER_APP_VBASE + U300_TIMER_APP_RGPT1);
/* Set up the IRQ handler */
setup_irq(IRQ_U300_TIMER_APP_GP1, &u300_timer_irq);
/* Reset the General Purpose timer 2 */
writel(U300_TIMER_APP_RGPT2_TIMER_RESET,
U300_TIMER_APP_VBASE + U300_TIMER_APP_RGPT2);
/* Set this timer to run around forever */
writel(0xFFFFFFFFU, U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT2TC);
/* Set continuous mode so it wraps around */
writel(U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS,
U300_TIMER_APP_VBASE + U300_TIMER_APP_SGPT2M);
/* Disable timer interrupts */
writel(U300_TIMER_APP_GPT2IE_IRQ_DISABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT2IE);
/* Then enable the GP2 timer to use as a free running us counter */
writel(U300_TIMER_APP_EGPT2_TIMER_ENABLE,
U300_TIMER_APP_VBASE + U300_TIMER_APP_EGPT2);
/* This is a pure microsecond clock source */
clocksource_u300_1mhz.mult =
clocksource_khz2mult(1000, clocksource_u300_1mhz.shift);
if (clocksource_register(&clocksource_u300_1mhz))
printk(KERN_ERR "timer: failed to initialize clock "
"source %s\n", clocksource_u300_1mhz.name);
clockevent_u300_1mhz.mult =
div_sc(1000000, NSEC_PER_SEC, clockevent_u300_1mhz.shift);
/* 32bit counter, so 32bits delta is max */
clockevent_u300_1mhz.max_delta_ns =
clockevent_delta2ns(0xffffffff, &clockevent_u300_1mhz);
/* This timer is slow enough to set for 1 cycle == 1 MHz */
clockevent_u300_1mhz.min_delta_ns =
clockevent_delta2ns(1, &clockevent_u300_1mhz);
clockevent_u300_1mhz.cpumask = cpumask_of(0);
clockevents_register_device(&clockevent_u300_1mhz);
/*
* TODO: init and register the rest of the timers too, they can be
* used by hrtimers!
*/
}
/*
* Very simple system timer that only register the clock event and
* clock source.
*/
struct sys_timer u300_timer = {
.init = u300_timer_init,
};
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