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alistair23-linux/arch/cris/arch-v10/kernel/time.c
Stephen Warren 7b1f62076b time: convert arch_gettimeoffset to a pointer 
Currently, whenever CONFIG_ARCH_USES_GETTIMEOFFSET is enabled, each
arch core provides a single implementation of arch_gettimeoffset(). In
many cases, different sub-architectures, different machines, or
different timer providers exist, and so the arch ends up implementing
arch_gettimeoffset() as a call-through-pointer anyway. Examples are
ARM, Cris, M68K, and it's arguable that the remaining architectures,
M32R and Blackfin, should be doing this anyway.

Modify arch_gettimeoffset so that it itself is a function pointer, which
the arch initializes. This will allow later changes to move the
initialization of this function into individual machine support or timer
drivers. This is particularly useful for code in drivers/clocksource
which should rely on an arch-independant mechanism to register their
implementation of arch_gettimeoffset().

This patch also converts the Cris architecture to set arch_gettimeoffset
directly to the final implementation in time_init(), because Cris already
had separate time_init() functions per sub-architecture. M68K and ARM
are converted to set arch_gettimeoffset to the final implementation in
later patches, because they already have function pointers in place for
this purpose.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
2012-12-24 09:36:07 -07:00

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/*
* linux/arch/cris/arch-v10/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* Copyright (C) 1999-2002 Axis Communications AB
*
*/
#include <linux/timex.h>
#include <linux/time.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/swap.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <arch/svinto.h>
#include <asm/types.h>
#include <asm/signal.h>
#include <asm/io.h>
#include <asm/delay.h>
#include <asm/irq_regs.h>
/* define this if you need to use print_timestamp */
/* it will make jiffies at 96 hz instead of 100 hz though */
#undef USE_CASCADE_TIMERS
unsigned long get_ns_in_jiffie(void)
{
unsigned char timer_count, t1;
unsigned short presc_count;
unsigned long ns;
unsigned long flags;
local_irq_save(flags);
timer_count = *R_TIMER0_DATA;
presc_count = *R_TIM_PRESC_STATUS;
/* presc_count might be wrapped */
t1 = *R_TIMER0_DATA;
if (timer_count != t1){
/* it wrapped, read prescaler again... */
presc_count = *R_TIM_PRESC_STATUS;
timer_count = t1;
}
local_irq_restore(flags);
if (presc_count >= PRESCALE_VALUE/2 ){
presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
} else {
presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
}
ns = ( (TIMER0_DIV - timer_count) * ((1000000000/HZ)/TIMER0_DIV )) +
( (presc_count) * (1000000000/PRESCALE_FREQ));
return ns;
}
static u32 cris_v10_gettimeoffset(void)
{
u32 count;
/* The timer interrupt comes from Etrax timer 0. In order to get
* better precision, we check the current value. It might have
* underflowed already though.
*/
count = *R_TIMER0_DATA;
/* Convert timer value to nsec */
return (TIMER0_DIV - count) * (NSEC_PER_SEC/HZ)/TIMER0_DIV;
}
/* Excerpt from the Etrax100 HSDD about the built-in watchdog:
*
* 3.10.4 Watchdog timer
* When the watchdog timer is started, it generates an NMI if the watchdog
* isn't restarted or stopped within 0.1 s. If it still isn't restarted or
* stopped after an additional 3.3 ms, the watchdog resets the chip.
* The watchdog timer is stopped after reset. The watchdog timer is controlled
* by the R_WATCHDOG register. The R_WATCHDOG register contains an enable bit
* and a 3-bit key value. The effect of writing to the R_WATCHDOG register is
* described in the table below:
*
* Watchdog Value written:
* state: To enable: To key: Operation:
* -------- ---------- ------- ----------
* stopped 0 X No effect.
* stopped 1 key_val Start watchdog with key = key_val.
* started 0 ~key Stop watchdog
* started 1 ~key Restart watchdog with key = ~key.
* started X new_key_val Change key to new_key_val.
*
* Note: '~' is the bitwise NOT operator.
*
*/
/* right now, starting the watchdog is the same as resetting it */
#define start_watchdog reset_watchdog
#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
static int watchdog_key = 0; /* arbitrary number */
#endif
/* number of pages to consider "out of memory". it is normal that the memory
* is used though, so put this really low.
*/
#define WATCHDOG_MIN_FREE_PAGES 8
void
reset_watchdog(void)
{
#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
/* only keep watchdog happy as long as we have memory left! */
if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) {
/* reset the watchdog with the inverse of the old key */
watchdog_key ^= 0x7; /* invert key, which is 3 bits */
*R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
IO_STATE(R_WATCHDOG, enable, start);
}
#endif
}
/* stop the watchdog - we still need the correct key */
void
stop_watchdog(void)
{
#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
watchdog_key ^= 0x7; /* invert key, which is 3 bits */
*R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
IO_STATE(R_WATCHDOG, enable, stop);
#endif
}
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "xtime_update()" routine every clocktick
*/
//static unsigned short myjiff; /* used by our debug routine print_timestamp */
extern void cris_do_profile(struct pt_regs *regs);
static inline irqreturn_t
timer_interrupt(int irq, void *dev_id)
{
struct pt_regs *regs = get_irq_regs();
/* acknowledge the timer irq */
#ifdef USE_CASCADE_TIMERS
*R_TIMER_CTRL =
IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
IO_STATE( R_TIMER_CTRL, i1, clr) |
IO_STATE( R_TIMER_CTRL, tm1, run) |
IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
IO_STATE( R_TIMER_CTRL, i0, clr) |
IO_STATE( R_TIMER_CTRL, tm0, run) |
IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
#else
*R_TIMER_CTRL = r_timer_ctrl_shadow |
IO_STATE(R_TIMER_CTRL, i0, clr);
#endif
/* reset watchdog otherwise it resets us! */
reset_watchdog();
/* Update statistics. */
update_process_times(user_mode(regs));
/* call the real timer interrupt handler */
xtime_update(1);
cris_do_profile(regs); /* Save profiling information */
return IRQ_HANDLED;
}
/* timer is IRQF_SHARED so drivers can add stuff to the timer irq chain
* it needs to be IRQF_DISABLED to make the jiffies update work properly
*/
static struct irqaction irq2 = {
.handler = timer_interrupt,
.flags = IRQF_SHARED | IRQF_DISABLED,
.name = "timer",
};
void __init
time_init(void)
{
arch_gettimeoffset = cris_v10_gettimeoffset;
/* probe for the RTC and read it if it exists
* Before the RTC can be probed the loops_per_usec variable needs
* to be initialized to make usleep work. A better value for
* loops_per_usec is calculated by the kernel later once the
* clock has started.
*/
loops_per_usec = 50;
/* Setup the etrax timers
* Base frequency is 25000 hz, divider 250 -> 100 HZ
* In normal mode, we use timer0, so timer1 is free. In cascade
* mode (which we sometimes use for debugging) both timers are used.
* Remember that linux/timex.h contains #defines that rely on the
* timer settings below (hz and divide factor) !!!
*/
#ifdef USE_CASCADE_TIMERS
*R_TIMER_CTRL =
IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
IO_STATE( R_TIMER_CTRL, i1, nop) |
IO_STATE( R_TIMER_CTRL, tm1, stop_ld) |
IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
IO_STATE( R_TIMER_CTRL, i0, nop) |
IO_STATE( R_TIMER_CTRL, tm0, stop_ld) |
IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
*R_TIMER_CTRL = r_timer_ctrl_shadow =
IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
IO_STATE( R_TIMER_CTRL, i1, nop) |
IO_STATE( R_TIMER_CTRL, tm1, run) |
IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
IO_STATE( R_TIMER_CTRL, i0, nop) |
IO_STATE( R_TIMER_CTRL, tm0, run) |
IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
#else
*R_TIMER_CTRL =
IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) |
IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) |
IO_STATE(R_TIMER_CTRL, i1, nop) |
IO_STATE(R_TIMER_CTRL, tm1, stop_ld) |
IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) |
IO_STATE(R_TIMER_CTRL, i0, nop) |
IO_STATE(R_TIMER_CTRL, tm0, stop_ld) |
IO_STATE(R_TIMER_CTRL, clksel0, flexible);
*R_TIMER_CTRL = r_timer_ctrl_shadow =
IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) |
IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) |
IO_STATE(R_TIMER_CTRL, i1, nop) |
IO_STATE(R_TIMER_CTRL, tm1, run) |
IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) |
IO_STATE(R_TIMER_CTRL, i0, nop) |
IO_STATE(R_TIMER_CTRL, tm0, run) |
IO_STATE(R_TIMER_CTRL, clksel0, flexible);
*R_TIMER_PRESCALE = PRESCALE_VALUE;
#endif
*R_IRQ_MASK0_SET =
IO_STATE(R_IRQ_MASK0_SET, timer0, set); /* unmask the timer irq */
/* now actually register the timer irq handler that calls timer_interrupt() */
setup_irq(2, &irq2); /* irq 2 is the timer0 irq in etrax */
/* enable watchdog if we should use one */
#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
printk("Enabling watchdog...\n");
start_watchdog();
/* If we use the hardware watchdog, we want to trap it as an NMI
and dump registers before it resets us. For this to happen, we
must set the "m" NMI enable flag (which once set, is unset only
when an NMI is taken).
The same goes for the external NMI, but that doesn't have any
driver or infrastructure support yet. */
asm ("setf m");
*R_IRQ_MASK0_SET =
IO_STATE(R_IRQ_MASK0_SET, watchdog_nmi, set);
*R_VECT_MASK_SET =
IO_STATE(R_VECT_MASK_SET, nmi, set);
#endif
}
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