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avr32: Generic clockevents support

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This combines three patches from David Brownell:
  * avr32: tclib support
  * avr32: simplify clocksources
  * avr32: Turn count/compare into a oneshot clockevent device

Register both TC blocks (instead of just the first one) so that
the AT32/AT91 tclib code will pick them up (instead of just the
avr32-only PIT-style clocksource).

Rename the first one and its resources appropriately.

More cleanups to the cycle counter clocksource code

 - Disable all the weak symbol magic; remove the AVR32-only TCB-based
   clocksource code (source and header).

 - Mark the __init code properly.

 - Don't forget to report IRQF_TIMER.

 - Make the system work properly with this clocksource, by preventing
   use of the CPU "idle" sleep state in the idle loop when it's used.

Package the avr32 count/compare timekeeping support as a oneshot
clockevent device, so it supports NO_HZ and high res timers.
This means it also supports plugging in other clockevent devices
and clocksources.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
This commit is contained in:
David Brownell 2008-02-14 11:24:02 -08:00 committed by Haavard Skinnemoen
parent 7e59128f31
commit e723ff666a
6 changed files with 117 additions and 477 deletions
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5
arch/avr32/Kconfig
View file

@ -47,6 +47,9 @@ config RWSEM_GENERIC_SPINLOCK
config GENERIC_TIME
def_bool y
config GENERIC_CLOCKEVENTS
def_bool y
config RWSEM_XCHGADD_ALGORITHM
def_bool n
@ -70,6 +73,8 @@ source "init/Kconfig"
menu "System Type and features"
source "kernel/time/Kconfig"
config SUBARCH_AVR32B
bool
config MMU

225
arch/avr32/kernel/time.c
View file

@ -1,16 +1,12 @@
/*
* 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/clockchips.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/interrupt.h>
@ -27,13 +23,10 @@
#include <asm/io.h>
#include <asm/sections.h>
/* how many counter cycles in a jiffy? */
static u32 cycles_per_jiffy;
#include <asm/arch/pm.h>
/* the count value for the next timer interrupt */
static u32 expirelo;
cycle_t __weak read_cycle_count(void)
static cycle_t read_cycle_count(void)
{
return (cycle_t)sysreg_read(COUNT);
}
@ -42,10 +35,11 @@ cycle_t __weak read_cycle_count(void)
* The architectural cycle count registers are a fine clocksource unless
* the system idle loop use sleep states like "idle": the CPU cycles
* measured by COUNT (and COMPARE) don't happen during sleep states.
* Their duration also changes if cpufreq changes the CPU clock rate.
* So we rate the clocksource using COUNT as very low quality.
*/
struct clocksource __weak clocksource_avr32 = {
.name = "avr32",
static struct clocksource counter = {
.name = "avr32_counter",
.rating = 50,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(32),
@ -53,152 +47,109 @@ struct clocksource __weak clocksource_avr32 = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
irqreturn_t __weak timer_interrupt(int irq, void *dev_id);
struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.name = "timer",
};
static void avr32_timer_ack(void)
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
u32 count;
/* Ack this timer interrupt and set the next one */
expirelo += cycles_per_jiffy;
/* setting COMPARE to 0 stops the COUNT-COMPARE */
if (expirelo == 0) {
sysreg_write(COMPARE, expirelo + 1);
} else {
sysreg_write(COMPARE, expirelo);
}
/* Check to see if we have missed any timer interrupts */
count = sysreg_read(COUNT);
if ((count - expirelo) < 0x7fffffff) {
expirelo = count + cycles_per_jiffy;
sysreg_write(COMPARE, expirelo);
}
}
int __weak avr32_hpt_init(void)
{
int ret;
unsigned long mult, shift, count_hz;
count_hz = clk_get_rate(boot_cpu_data.clk);
shift = clocksource_avr32.shift;
mult = clocksource_hz2mult(count_hz, shift);
clocksource_avr32.mult = mult;
{
u64 tmp;
tmp = TICK_NSEC;
tmp <<= shift;
tmp += mult / 2;
do_div(tmp, mult);
cycles_per_jiffy = tmp;
}
ret = setup_irq(0, &timer_irqaction);
if (ret) {
pr_debug("timer: could not request IRQ 0: %d\n", ret);
return -ENODEV;
}
printk(KERN_INFO "timer: AT32AP COUNT-COMPARE at irq 0, "
"%lu.%03lu MHz\n",
((count_hz + 500) / 1000) / 1000,
((count_hz + 500) / 1000) % 1000);
return 0;
}
/*
* Taken from MIPS c0_hpt_timer_init().
*
* The reason COUNT is written twice is probably to make sure we don't get any
* timer interrupts while we are messing with the counter.
*/
int __weak avr32_hpt_start(void)
{
u32 count = sysreg_read(COUNT);
expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
sysreg_write(COUNT, expirelo - cycles_per_jiffy);
sysreg_write(COMPARE, expirelo);
sysreg_write(COUNT, count);
return 0;
}
/*
* local_timer_interrupt() does profiling and process accounting on a
* per-CPU basis.
*
* In UP mode, it is invoked from the (global) timer_interrupt.
*/
void local_timer_interrupt(int irq, void *dev_id)
{
if (current->pid)
profile_tick(CPU_PROFILING);
update_process_times(user_mode(get_irq_regs()));
}
irqreturn_t __weak timer_interrupt(int irq, void *dev_id)
{
/* ack timer interrupt and try to set next interrupt */
avr32_timer_ack();
struct clock_event_device *evdev = dev_id;
/*
* Call the generic timer interrupt handler
* Disable the interrupt until the clockevent subsystem
* reprograms it.
*/
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);
sysreg_write(COMPARE, 0);
evdev->event_handler(evdev);
return IRQ_HANDLED;
}
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_TIMER | IRQF_DISABLED,
.name = "avr32_comparator",
};
static int comparator_next_event(unsigned long delta,
struct clock_event_device *evdev)
{
unsigned long flags;
raw_local_irq_save(flags);
/* The time to read COUNT then update COMPARE must be less
* than the min_delta_ns value for this clockevent source.
*/
sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
raw_local_irq_restore(flags);
return 0;
}
static void comparator_mode(enum clock_event_mode mode,
struct clock_event_device *evdev)
{
switch (mode) {
case CLOCK_EVT_MODE_ONESHOT:
pr_debug("%s: start\n", evdev->name);
/* FALLTHROUGH */
case CLOCK_EVT_MODE_RESUME:
cpu_disable_idle_sleep();
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
sysreg_write(COMPARE, 0);
pr_debug("%s: stop\n", evdev->name);
cpu_enable_idle_sleep();
break;
default:
BUG();
}
}
static struct clock_event_device comparator = {
.name = "avr32_comparator",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 16,
.rating = 50,
.cpumask = CPU_MASK_CPU0,
.set_next_event = comparator_next_event,
.set_mode = comparator_mode,
};
void __init time_init(void)
{
unsigned long counter_hz;
int ret;
/*
* Make sure we don't get any COMPARE interrupts before we can
* handle them.
*/
sysreg_write(COMPARE, 0);
xtime.tv_sec = mktime(2007, 1, 1, 0, 0, 0);
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
ret = avr32_hpt_init();
if (ret) {
pr_debug("timer: failed setup: %d\n", ret);
return;
}
/* figure rate for counter */
counter_hz = clk_get_rate(boot_cpu_data.clk);
counter.mult = clocksource_hz2mult(counter_hz, counter.shift);
ret = clocksource_register(&clocksource_avr32);
ret = clocksource_register(&counter);
if (ret)
pr_debug("timer: could not register clocksource: %d\n", ret);
ret = avr32_hpt_start();
if (ret) {
pr_debug("timer: failed starting: %d\n", ret);
return;
/* setup COMPARE clockevent */
comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
sysreg_write(COMPARE, 0);
timer_irqaction.dev_id = &comparator;
ret = setup_irq(0, &timer_irqaction);
if (ret)
pr_debug("timer: could not request IRQ 0: %d\n", ret);
else {
clockevents_register_device(&comparator);
pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
((counter_hz + 500) / 1000) / 1000,
((counter_hz + 500) / 1000) % 1000);
}
}

1
arch/avr32/mach-at32ap/Makefile
View file

@ -1,4 +1,3 @@
obj-y += at32ap.o clock.o intc.o extint.o pio.o hsmc.o
obj-$(CONFIG_CPU_AT32AP700X) += at32ap700x.o pm-at32ap700x.o
obj-$(CONFIG_CPU_AT32AP700X) += time-tc.o
obj-$(CONFIG_CPU_FREQ_AT32AP) += cpufreq.o

33
arch/avr32/mach-at32ap/at32ap700x.c
View file

@ -606,19 +606,32 @@ static inline void set_ebi_sfr_bits(u32 mask)
}
/* --------------------------------------------------------------------
* System Timer/Counter (TC)
* Timer/Counter (TC)
* -------------------------------------------------------------------- */
static struct resource at32_systc0_resource[] = {
static struct resource at32_tcb0_resource[] = {
PBMEM(0xfff00c00),
IRQ(22),
};
struct platform_device at32_systc0_device = {
.name = "systc",
static struct platform_device at32_tcb0_device = {
.name = "atmel_tcb",
.id = 0,
.resource = at32_systc0_resource,
.num_resources = ARRAY_SIZE(at32_systc0_resource),
.resource = at32_tcb0_resource,
.num_resources = ARRAY_SIZE(at32_tcb0_resource),
};
DEV_CLK(pclk, at32_systc0, pbb, 3);
DEV_CLK(t0_clk, at32_tcb0, pbb, 3);
static struct resource at32_tcb1_resource[] = {
PBMEM(0xfff01000),
IRQ(23),
};
static struct platform_device at32_tcb1_device = {
.name = "atmel_tcb",
.id = 1,
.resource = at32_tcb1_resource,
.num_resources = ARRAY_SIZE(at32_tcb1_resource),
};
DEV_CLK(t0_clk, at32_tcb1, pbb, 4);
/* --------------------------------------------------------------------
* PIO
@ -670,7 +683,8 @@ void __init at32_add_system_devices(void)
platform_device_register(&pdc_device);
platform_device_register(&dmaca0_device);
platform_device_register(&at32_systc0_device);
platform_device_register(&at32_tcb0_device);
platform_device_register(&at32_tcb1_device);
platform_device_register(&pio0_device);
platform_device_register(&pio1_device);
@ -1737,7 +1751,8 @@ struct clk *at32_clock_list[] = {
&pio2_mck,
&pio3_mck,
&pio4_mck,
&at32_systc0_pclk,
&at32_tcb0_t0_clk,
&at32_tcb1_t0_clk,
&atmel_usart0_usart,
&atmel_usart1_usart,
&atmel_usart2_usart,

218
arch/avr32/mach-at32ap/time-tc.c
View file

@ -1,218 +0,0 @@
/*
* 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 = ARRAY_SIZE(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;
}

112
include/asm-avr32/arch-at32ap/time.h
View file

@ -1,112 +0,0 @@
/*
* Copyright (C) 2007 Atmel Corporation
*
* 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.
*/
#ifndef _ASM_AVR32_ARCH_AT32AP_TIME_H
#define _ASM_AVR32_ARCH_AT32AP_TIME_H
#include <linux/platform_device.h>
extern struct irqaction timer_irqaction;
extern struct platform_device at32_systc0_device;
extern void local_timer_interrupt(int irq, void *dev_id);
#define TIMER_BCR 0x000000c0
#define TIMER_BCR_SYNC 0
#define TIMER_BMR 0x000000c4
#define TIMER_BMR_TC0XC0S 0
#define TIMER_BMR_TC1XC1S 2
#define TIMER_BMR_TC2XC2S 4
#define TIMER_CCR 0x00000000
#define TIMER_CCR_CLKDIS 1
#define TIMER_CCR_CLKEN 0
#define TIMER_CCR_SWTRG 2
#define TIMER_CMR 0x00000004
#define TIMER_CMR_ABETRG 10
#define TIMER_CMR_ACPA 16
#define TIMER_CMR_ACPC 18
#define TIMER_CMR_AEEVT 20
#define TIMER_CMR_ASWTRG 22
#define TIMER_CMR_BCPB 24
#define TIMER_CMR_BCPC 26
#define TIMER_CMR_BEEVT 28
#define TIMER_CMR_BSWTRG 30
#define TIMER_CMR_BURST 4
#define TIMER_CMR_CLKI 3
#define TIMER_CMR_CPCDIS 7
#define TIMER_CMR_CPCSTOP 6
#define TIMER_CMR_CPCTRG 14
#define TIMER_CMR_EEVT 10
#define TIMER_CMR_EEVTEDG 8
#define TIMER_CMR_ENETRG 12
#define TIMER_CMR_ETRGEDG 8
#define TIMER_CMR_LDBDIS 7
#define TIMER_CMR_LDBSTOP 6
#define TIMER_CMR_LDRA 16
#define TIMER_CMR_LDRB 18
#define TIMER_CMR_TCCLKS 0
#define TIMER_CMR_WAVE 15
#define TIMER_CMR_WAVSEL 13
#define TIMER_CV 0x00000010
#define TIMER_CV_CV 0
#define TIMER_IDR 0x00000028
#define TIMER_IDR_COVFS 0
#define TIMER_IDR_CPAS 2
#define TIMER_IDR_CPBS 3
#define TIMER_IDR_CPCS 4
#define TIMER_IDR_ETRGS 7
#define TIMER_IDR_LDRAS 5
#define TIMER_IDR_LDRBS 6
#define TIMER_IDR_LOVRS 1
#define TIMER_IER 0x00000024
#define TIMER_IER_COVFS 0
#define TIMER_IER_CPAS 2
#define TIMER_IER_CPBS 3
#define TIMER_IER_CPCS 4
#define TIMER_IER_ETRGS 7
#define TIMER_IER_LDRAS 5
#define TIMER_IER_LDRBS 6
#define TIMER_IER_LOVRS 1
#define TIMER_IMR 0x0000002c
#define TIMER_IMR_COVFS 0
#define TIMER_IMR_CPAS 2
#define TIMER_IMR_CPBS 3
#define TIMER_IMR_CPCS 4
#define TIMER_IMR_ETRGS 7
#define TIMER_IMR_LDRAS 5
#define TIMER_IMR_LDRBS 6
#define TIMER_IMR_LOVRS 1
#define TIMER_RA 0x00000014
#define TIMER_RA_RA 0
#define TIMER_RB 0x00000018
#define TIMER_RB_RB 0
#define TIMER_RC 0x0000001c
#define TIMER_RC_RC 0
#define TIMER_SR 0x00000020
#define TIMER_SR_CLKSTA 16
#define TIMER_SR_COVFS 0
#define TIMER_SR_CPAS 2
#define TIMER_SR_CPBS 3
#define TIMER_SR_CPCS 4
#define TIMER_SR_ETRGS 7
#define TIMER_SR_LDRAS 5
#define TIMER_SR_LDRBS 6
#define TIMER_SR_LOVRS 1
#define TIMER_SR_MTIOA 17
#define TIMER_SR_MTIOB 18
/* Bit manipulation macros */
#define TIMER_BIT(name) (1 << TIMER_##name)
#define TIMER_BF(name,value) ((value) << TIMER_##name)
/* Register access macros */
#define timer_read(port,instance,reg) \
__raw_readl(port + (0x40 * instance) + TIMER_##reg)
#define timer_write(port,instance,reg,value) \
__raw_writel((value), port + (0x40 * instance) + TIMER_##reg)
#endif /* _ASM_AVR32_ARCH_AT32AP_TIME_H */