Trivial clocksource driver

From: Mason
Date: Tue Sep 29 2015 - 12:26:18 EST

Hello everyone,

I am trying to submit a new ARM port, and Arnd pointed out that the
clocksource code could not live in arch/arm/$PLATFORM, but had to
move to drivers/clocksource (and it had to support DT).

Did I understand correctly? Is this the right place to submit code
as provided below?


#include <linux/delay.h> /* register_current_timer_delay */
#include <linux/clocksource.h> /* clocksource_register_hz */
#include <linux/sched_clock.h> /* sched_clock_register */
#include <linux/of_address.h> /* of_iomap */
#include <linux/clk.h> /* of_clk_get, clk_get_rate */

static void __iomem *xtal_in_cnt;
static struct delay_timer delay_timer;

static unsigned long read_xtal_counter(void)
return readl_relaxed(xtal_in_cnt);

static u64 read_sched_clock(void)
return read_xtal_counter();

static cycle_t read_clocksource(struct clocksource *cs)
return read_xtal_counter();

static struct clocksource tango_xtal = {
.name = "tango-xtal",
.rating = 350,
.read = read_clocksource,

static void __init tango_clksrc_init(struct device_node *np)
struct clk *clk = of_clk_get(np, 0);
unsigned int xtal_freq = clk_get_rate(clk);
xtal_in_cnt = of_iomap(np, 0);

delay_timer.freq = xtal_freq;
delay_timer.read_current_timer = read_xtal_counter;
sched_clock_register(read_sched_clock, 32, xtal_freq);
clocksource_register_hz(&tango_xtal, xtal_freq);

CLOCKSOURCE_OF_DECLARE(tango, "sigma,xtal_in_cnt", tango_clksrc_init);
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