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/**
* timer-ti-32k.c - OMAP2 32k Timer Support
*
* Copyright (C) 2009 Nokia Corporation
*
* Update to use new clocksource/clockevent layers
* Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
* Copyright (C) 2007 MontaVista Software, Inc.
*
* Original driver:
* Copyright (C) 2005 Nokia Corporation
* Author: Paul Mundt <paul.mundt@nokia.com>
* Juha Yrjölä <juha.yrjola@nokia.com>
* OMAP Dual-mode timer framework support by Timo Teras
*
* Some parts based off of TI's 24xx code:
*
* Copyright (C) 2004-2009 Texas Instruments, Inc.
*
* Roughly modelled after the OMAP1 MPU timer code.
* Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* Copyright (C) 2015 Texas Instruments Incorporated - http://www.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 of
* the License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/init.h>
#include <linux/time.h>
#include <linux/sched_clock.h>
#include <linux/clocksource.h>
#include <linux/of.h>
#include <linux/of_address.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 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
struct ti_32k {
void __iomem *base;
void __iomem *counter;
struct clocksource cs;
};
static inline struct ti_32k *to_ti_32k(struct clocksource *cs)
{
return container_of(cs, struct ti_32k, cs);
}
static u64 notrace ti_32k_read_cycles(struct clocksource *cs)
{
struct ti_32k *ti = to_ti_32k(cs);
return (u64)readl_relaxed(ti->counter);
}
static struct ti_32k ti_32k_timer = {
.cs = {
.name = "32k_counter",
.rating = 250,
.read = ti_32k_read_cycles,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_SUSPEND_NONSTOP,
},
};
static u64 notrace omap_32k_read_sched_clock(void)
{
return ti_32k_read_cycles(&ti_32k_timer.cs);
}
static int __init ti_32k_timer_init(struct device_node *np)
{
int ret;
ti_32k_timer.base = of_iomap(np, 0);
if (!ti_32k_timer.base) {
pr_err("Can't ioremap 32k timer base\n");
return -ENXIO;
}
ti_32k_timer.counter = ti_32k_timer.base;
/*
* 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(ti_32k_timer.base + OMAP2_32KSYNCNT_REV_OFF) &
OMAP2_32KSYNCNT_REV_SCHEME)
ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_HIGH;
else
ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_LOW;
ret = clocksource_register_hz(&ti_32k_timer.cs, 32768);
if (ret) {
pr_err("32k_counter: can't register clocksource\n");
return ret;
}
sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
return 0;
}
CLOCKSOURCE_OF_DECLARE(ti_32k_timer, "ti,omap-counter32k",
ti_32k_timer_init);
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