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linux/arch/arm/mach-u300/timer.c
Marc Zyngier 2f0778afac ARM: 7205/2: sched_clock: allow sched_clock to be selected at runtime 
sched_clock() is yet another blocker on the road to the single
image. This patch implements an idea by Russell King:

http://www.spinics.net/lists/linux-omap/msg49561.html

Instead of asking the platform to implement both sched_clock()
itself and the rollover callback, simply register a read()
function, and let the ARM code care about sched_clock() itself,
the conversion to ns and the rollover. sched_clock() uses
this read() function as an indirection to the platform code.
If the platform doesn't provide a read(), the code falls back
to the jiffy counter (just like the default sched_clock).

This allow some simplifications and possibly some footprint gain
when multiple platforms are compiled in. Among the drawbacks,
the removal of the *_fixed_sched_clock optimization which could
negatively impact some platforms (sa1100, tegra, versatile
and omap).

Tested on 11MPCore, OMAP4 and Tegra.

Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Cc: STEricsson <STEricsson_nomadik_linux@list.st.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Tested-by: Jamie Iles <jamie@jamieiles.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-12-18 23:00:26 +00:00

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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 <linux/clk.h>
#include <linux/err.h>
#include <mach/hardware.h>
/* Generic stuff */
#include <asm/sched_clock.h>
#include <asm/mach/map.h>
#include <asm/mach/time.h>
#include <asm/mach/irq.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,
.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,
};
/*
* 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.)
*/
static u32 notrace u300_read_sched_clock(void)
{
return readl(U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT2CC);
}
/*
* This sets up the system timers, clock source and clock event.
*/
static void __init u300_timer_init(void)
{
struct clk *clk;
unsigned long rate;
/* Clock the interrupt controller */
clk = clk_get_sys("apptimer", NULL);
BUG_ON(IS_ERR(clk));
clk_enable(clk);
rate = clk_get_rate(clk);
setup_sched_clock(u300_read_sched_clock, 32, rate);
/*
* 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);
/* Use general purpose timer 2 as clock source */
if (clocksource_mmio_init(U300_TIMER_APP_VBASE + U300_TIMER_APP_GPT2CC,
"GPT2", rate, 300, 32, clocksource_mmio_readl_up))
pr_err("timer: failed to initialize U300 clock source\n");
/* Configure and register the clockevent */
clockevents_config_and_register(&clockevent_u300_1mhz, rate,
1, 0xffffffff);
/*
* 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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