linux_old1/arch/arm/plat-omap/counter_32k.c

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/*
* OMAP 32ksynctimer/counter_32k-related code
*
* Copyright (C) 2009 Texas Instruments
* Copyright (C) 2010 Nokia Corporation
* Tony Lindgren <tony@atomide.com>
* Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* 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.
*
* NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/sched.h>
#include <asm/sched_clock.h>
#include <plat/common.h>
#include <plat/board.h>
#include <plat/clock.h>
/*
* 32KHz clocksource ... always available, on pretty most chips except
* OMAP 730 and 1510. Other timers could be used as clocksources, with
* higher resolution in free-running counter modes (e.g. 12 MHz xtal),
* but systems won't necessarily want to spend resources that way.
*/
#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
#include <linux/clocksource.h>
/*
* offset_32k holds the init time counter value. It is then subtracted
* from every counter read to achieve a counter that counts time from the
* kernel boot (needed for sched_clock()).
*/
static u32 offset_32k __read_mostly;
#ifdef CONFIG_ARCH_OMAP16XX
static cycle_t notrace omap16xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k;
}
#else
#define omap16xx_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP2420
static cycle_t notrace omap2420_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2420_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP2430
static cycle_t notrace omap2430_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2430_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP3
static cycle_t notrace omap34xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap34xx_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP4
static cycle_t notrace omap44xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap44xx_32k_read NULL
#endif
/*
* Kernel assumes that sched_clock can be called early but may not have
* things ready yet.
*/
static cycle_t notrace omap_32k_read_dummy(struct clocksource *cs)
{
return 0;
}
static struct clocksource clocksource_32k = {
.name = "32k_counter",
.rating = 250,
.read = omap_32k_read_dummy,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Returns current time from boot in nsecs. It's OK for this to wrap
* around for now, as it's just a relative time stamp.
*/
static DEFINE_CLOCK_DATA(cd);
/*
* Constants generated by clocks_calc_mult_shift(m, s, 32768, NSEC_PER_SEC, 60).
* This gives a resolution of about 30us and a wrap period of about 36hrs.
*/
#define SC_MULT 4000000000u
#define SC_SHIFT 17
static inline unsigned long long notrace _omap_32k_sched_clock(void)
{
u32 cyc = clocksource_32k.read(&clocksource_32k);
return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
}
#ifndef CONFIG_OMAP_MPU_TIMER
unsigned long long notrace sched_clock(void)
{
return _omap_32k_sched_clock();
}
#else
unsigned long long notrace omap_32k_sched_clock(void)
{
return _omap_32k_sched_clock();
}
#endif
static void notrace omap_update_sched_clock(void)
{
u32 cyc = clocksource_32k.read(&clocksource_32k);
update_sched_clock(&cd, cyc, (u32)~0);
}
/**
* read_persistent_clock - Return time from a persistent clock.
*
* Reads the time from a source which isn't disabled during PM, the
* 32k sync timer. Convert the cycles elapsed since last read into
* nsecs and adds to a monotonically increasing timespec.
*/
static struct timespec persistent_ts;
static cycles_t cycles, last_cycles;
void read_persistent_clock(struct timespec *ts)
{
unsigned long long nsecs;
cycles_t delta;
struct timespec *tsp = &persistent_ts;
last_cycles = cycles;
cycles = clocksource_32k.read(&clocksource_32k);
delta = cycles - last_cycles;
nsecs = clocksource_cyc2ns(delta,
clocksource_32k.mult, clocksource_32k.shift);
timespec_add_ns(tsp, nsecs);
*ts = *tsp;
}
OMAP: counter_32k: init clocksource as part of machine timer init After commit dc548fbbd2ecd0fc3b02301d551e5f8e19ae58fd ("ARM: omap: convert sched_clock() to use new infrastructure"), OMAPs that use the 32KiHz "synchronization timer" as their clocksource crash during boot: [ 0.000000] OMAP clockevent source: GPTIMER1 at 32768 Hz [ 0.000000] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 0.000000] pgd = c0004000 [ 0.000000] [00000000] *pgd=00000000 [ 0.000000] Internal error: Oops: 80000005 [#1] SMP [ 0.000000] last sysfs file: [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 Tainted: G W (2.6.37-07734-g2467802 #7) [ 0.000000] PC is at 0x0 [ 0.000000] LR is at sched_clock_poll+0x2c/0x3c [ 0.000000] pc : [<00000000>] lr : [<c0060b74>] psr: 600001d3 [ 0.000000] sp : c058bfd0 ip : c058a000 fp : 00000000 [ 0.000000] r10: 00000000 r9 : 411fc092 r8 : 800330c8 [ 0.000000] r7 : c05a08e0 r6 : c0034c48 r5 : c05ffc40 r4 : c0034c4c [ 0.000000] r3 : c05ffe6c r2 : c05a0bc0 r1 : c059f098 r0 : 00000000 [ 0.000000] Flags: nZCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel [ 0.000000] Control: 10c53c7f Table: 8000404a DAC: 00000017 This is due to the recent ARM init_sched_clock() changes and the late initialization of the counter_32k clock source. More information here: http://marc.info/?l=linux-omap&m=129513468605208&w=2 Fix by initializing the counter_32k clocksource during the machine timer initialization. Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Tested-by: Thomas Weber <weber@corscience.de> Signed-off-by: Paul Walmsley <paul@pwsan.com>
2011-01-16 12:32:01 +08:00
int __init omap_init_clocksource_32k(void)
{
static char err[] __initdata = KERN_ERR
"%s: can't register clocksource!\n";
if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
struct clk *sync_32k_ick;
if (cpu_is_omap16xx())
clocksource_32k.read = omap16xx_32k_read;
else if (cpu_is_omap2420())
clocksource_32k.read = omap2420_32k_read;
else if (cpu_is_omap2430())
clocksource_32k.read = omap2430_32k_read;
else if (cpu_is_omap34xx())
clocksource_32k.read = omap34xx_32k_read;
else if (cpu_is_omap44xx())
clocksource_32k.read = omap44xx_32k_read;
else
return -ENODEV;
sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
if (!IS_ERR(sync_32k_ick))
clk_enable(sync_32k_ick);
offset_32k = clocksource_32k.read(&clocksource_32k);
if (clocksource_register_hz(&clocksource_32k, 32768))
printk(err, clocksource_32k.name);
init_fixed_sched_clock(&cd, omap_update_sched_clock, 32,
32768, SC_MULT, SC_SHIFT);
}
return 0;
}