/*
* linux/arch/arm/mach-omap1/timer32k.c
*
* OMAP 32K Timer
*
* Copyright (C) 2004 - 2005 Nokia Corporation
* Partial timer rewrite and additional dynamic tick timer support by
* Tony Lindgen <[email protected]> and
* Tuukka Tikkanen <[email protected]>
* OMAP Dual-mode timer framework support by Timo Teras
*
* MPU timer code based on the older MPU timer code for OMAP
* Copyright (C) 2000 RidgeRun, Inc.
* Author: Greg Lonnon <[email protected]>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/io.h>
#include <linux/sched_clock.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include "hardware.h"
#include "common.h"
/*
* ---------------------------------------------------------------------------
* 32KHz OS timer
*
* This currently works only on 16xx, as 1510 does not have the continuous
* 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
* of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
* on 1510 would be possible, but the timer would not be as accurate as
* with the 32KHz synchronized timer.
* ---------------------------------------------------------------------------
*/
/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE 0xfffb9000
#define OMAP1_32KSYNC_TIMER_BASE 0xfffbc400
#define OMAP1_32K_TIMER_CR 0x08
#define OMAP1_32K_TIMER_TVR 0x00
#define OMAP1_32K_TIMER_TCR 0x04
#define OMAP_32K_TICKS_PER_SEC (32768)
/*
* TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
* so with HZ = 128, TVR = 255.
*/
#define OMAP_32K_TIMER_TICK_PERIOD ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate) \
(((nr_jiffies) * (clock_rate)) / HZ)
static inline void omap_32k_timer_write(int val, int reg)
{
omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
}
static inline void omap_32k_timer_start(unsigned long load_val)
{
if (!load_val)
load_val = 1;
omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
}
static inline void omap_32k_timer_stop(void)
{
omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
}
#define omap_32k_timer_ack_irq()
static int omap_32k_timer_set_next_event(unsigned long delta,
struct clock_event_device *dev)
{
omap_32k_timer_start(delta);
return 0;
}
static int omap_32k_timer_shutdown(struct clock_event_device *evt)
{
omap_32k_timer_stop();
return 0;
}
static int omap_32k_timer_set_periodic(struct clock_event_device *evt)
{
omap_32k_timer_stop();
omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
return 0;
}
static struct clock_event_device clockevent_32k_timer = {
.name = "32k-timer",
.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = omap_32k_timer_set_next_event,
.set_state_shutdown = omap_32k_timer_shutdown,
.set_state_periodic = omap_32k_timer_set_periodic,
.set_state_oneshot = omap_32k_timer_shutdown,
.tick_resume = omap_32k_timer_shutdown,
};
static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_32k_timer;
omap_32k_timer_ack_irq();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static __init void omap_init_32k_timer(void)
{
if (request_irq(INT_OS_TIMER, omap_32k_timer_interrupt,
IRQF_TIMER | IRQF_IRQPOLL, "32KHz timer", NULL))
pr_err("Failed to request irq %d(32KHz timer)\n", INT_OS_TIMER);
clockevent_32k_timer.cpumask = cpumask_of(0);
clockevents_config_and_register(&clockevent_32k_timer,
OMAP_32K_TICKS_PER_SEC, 1, 0xfffffffe);
}
/* OMAP2_32KSYNCNT_CR_OFF: offset of 32ksync counter register */
#define OMAP2_32KSYNCNT_REV_OFF 0x0
#define OMAP2_32KSYNCNT_REV_SCHEME (0x3 << 30)
#define OMAP2_32KSYNCNT_CR_OFF_LOW 0x10
#define OMAP2_32KSYNCNT_CR_OFF_HIGH 0x30
/*
* 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.
*/
static void __iomem *sync32k_cnt_reg;
static u64 notrace omap_32k_read_sched_clock(void)
{
return sync32k_cnt_reg ? readl_relaxed(sync32k_cnt_reg) : 0;
}
static struct timespec64 persistent_ts;
static cycles_t cycles;
static unsigned int persistent_mult, persistent_shift;
/**
* omap_read_persistent_clock64 - Return time from a persistent clock.
* @ts: &struct timespec64 for the returned time
*
* 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 timespec64.
*/
static void omap_read_persistent_clock64(struct timespec64 *ts)
{
unsigned long long nsecs;
cycles_t last_cycles;
last_cycles = cycles;
cycles = sync32k_cnt_reg ? readl_relaxed(sync32k_cnt_reg) : 0;
nsecs = clocksource_cyc2ns(cycles - last_cycles,
persistent_mult, persistent_shift);
timespec64_add_ns(&persistent_ts, nsecs);
*ts = persistent_ts;
}
/**
* omap_init_clocksource_32k - setup and register counter 32k as a
* kernel clocksource
* @vbase: base addr of counter_32k module
*
* Returns: %0 upon success or negative error code upon failure.
*
*/
static int __init omap_init_clocksource_32k(void __iomem *vbase)
{
int ret;
/*
* 32k sync Counter IP register offsets vary between the
* highlander version and the legacy ones.
* The 'SCHEME' bits(30-31) of the revision register is used
* to identify the version.
*/
if (readl_relaxed(vbase + OMAP2_32KSYNCNT_REV_OFF) &
OMAP2_32KSYNCNT_REV_SCHEME)
sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_HIGH;
else
sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_LOW;
/*
* 120000 rough estimate from the calculations in
* __clocksource_update_freq_scale.
*/
clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
32768, NSEC_PER_SEC, 120000);
ret = clocksource_mmio_init(sync32k_cnt_reg, "32k_counter", 32768,
250, 32, clocksource_mmio_readl_up);
if (ret) {
pr_err("32k_counter: can't register clocksource\n");
return ret;
}
sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
register_persistent_clock(omap_read_persistent_clock64);
pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
return 0;
}
/*
* ---------------------------------------------------------------------------
* Timer initialization
* ---------------------------------------------------------------------------
*/
int __init omap_32k_timer_init(void)
{
int ret = -ENODEV;
if (cpu_is_omap16xx()) {
void __iomem *base;
struct clk *sync32k_ick;
base = ioremap(OMAP1_32KSYNC_TIMER_BASE, SZ_1K);
if (!base) {
pr_err("32k_counter: failed to map base addr\n");
return -ENODEV;
}
sync32k_ick = clk_get(NULL, "omap_32ksync_ick");
if (!IS_ERR(sync32k_ick))
clk_prepare_enable(sync32k_ick);
ret = omap_init_clocksource_32k(base);
}
if (!ret)
omap_init_32k_timer();
return ret;
}
Codebase Browser
linux