arch/m68k/68000/timers.c

Source file repositories/reference/linux-study-clean/arch/m68k/68000/timers.c

File Facts

System
Linux kernel
Corpus path
arch/m68k/68000/timers.c
Extension
.c
Size
3376 bytes
Lines
138
Domain
Architecture Layer
Bucket
arch/m68k
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clocksource.h>
#include <linux/rtc.h>
#include <asm/setup.h>
#include <asm/machdep.h>
#include <asm/MC68VZ328.h>

#include "m68328.h"

/***************************************************************************/

#if defined(CONFIG_DRAGEN2)
/* with a 33.16 MHz clock, this will give usec resolution to the time functions */
#define CLOCK_SOURCE	TCTL_CLKSOURCE_SYSCLK
#define CLOCK_PRE	7
#define TICKS_PER_JIFFY	41450

#elif defined(CONFIG_XCOPILOT_BUGS)
/*
 * The only thing I know is that CLK32 is not available on Xcopilot
 * I have little idea about what frequency SYSCLK has on Xcopilot.
 * The values for prescaler and compare registers were simply
 * taken from the original source
 */
#define CLOCK_SOURCE	TCTL_CLKSOURCE_SYSCLK
#define CLOCK_PRE	2
#define TICKS_PER_JIFFY	0xd7e4

#else
/* default to using the 32Khz clock */
#define CLOCK_SOURCE	TCTL_CLKSOURCE_32KHZ
#define CLOCK_PRE	31
#define TICKS_PER_JIFFY	10
#endif

static u32 m68328_tick_cnt;

/***************************************************************************/

static irqreturn_t hw_tick(int irq, void *dummy)
{
	/* Reset Timer1 */
	TSTAT &= 0;

	m68328_tick_cnt += TICKS_PER_JIFFY;
	legacy_timer_tick(1);
	return IRQ_HANDLED;
}

/***************************************************************************/

static u64 m68328_read_clk(struct clocksource *cs)
{
	unsigned long flags;
	u32 cycles;

	local_irq_save(flags);
	cycles = m68328_tick_cnt + TCN;
	local_irq_restore(flags);

	return cycles;
}

/***************************************************************************/

static struct clocksource m68328_clk = {
	.name	= "timer",
	.rating	= 250,
	.read	= m68328_read_clk,
	.mask	= CLOCKSOURCE_MASK(32),
	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
};

/***************************************************************************/

void hw_timer_init(void)
{
	int ret;

	/* disable timer 1 */
	TCTL = 0;

	/* set ISR */
	ret = request_irq(TMR_IRQ_NUM, hw_tick, IRQF_TIMER, "timer", NULL);
	if (ret) {
		pr_err("Failed to request irq %d (timer): %pe\n", TMR_IRQ_NUM,

Annotation

Implementation Notes