linux/drivers/clocksource/em_sti.c

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/*
* Emma Mobile Timer Support - STI
*
* Copyright (C) 2012 Magnus Damm
*
* 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
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/slab.h>
#include <linux/module.h>
enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
struct em_sti_priv {
void __iomem *base;
struct clk *clk;
struct platform_device *pdev;
unsigned int active[USER_NR];
unsigned long rate;
raw_spinlock_t lock;
struct clock_event_device ced;
struct clocksource cs;
};
#define STI_CONTROL 0x00
#define STI_COMPA_H 0x10
#define STI_COMPA_L 0x14
#define STI_COMPB_H 0x18
#define STI_COMPB_L 0x1c
#define STI_COUNT_H 0x20
#define STI_COUNT_L 0x24
#define STI_COUNT_RAW_H 0x28
#define STI_COUNT_RAW_L 0x2c
#define STI_SET_H 0x30
#define STI_SET_L 0x34
#define STI_INTSTATUS 0x40
#define STI_INTRAWSTATUS 0x44
#define STI_INTENSET 0x48
#define STI_INTENCLR 0x4c
#define STI_INTFFCLR 0x50
static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
{
return ioread32(p->base + offs);
}
static inline void em_sti_write(struct em_sti_priv *p, int offs,
unsigned long value)
{
iowrite32(value, p->base + offs);
}
static int em_sti_enable(struct em_sti_priv *p)
{
int ret;
/* enable clock */
ret = clk_prepare_enable(p->clk);
if (ret) {
dev_err(&p->pdev->dev, "cannot enable clock\n");
return ret;
}
/* configure channel, periodic mode and maximum timeout */
p->rate = clk_get_rate(p->clk);
/* reset the counter */
em_sti_write(p, STI_SET_H, 0x40000000);
em_sti_write(p, STI_SET_L, 0x00000000);
/* mask and clear pending interrupts */
em_sti_write(p, STI_INTENCLR, 3);
em_sti_write(p, STI_INTFFCLR, 3);
/* enable updates of counter registers */
em_sti_write(p, STI_CONTROL, 1);
return 0;
}
static void em_sti_disable(struct em_sti_priv *p)
{
/* mask interrupts */
em_sti_write(p, STI_INTENCLR, 3);
/* stop clock */
clk_disable_unprepare(p->clk);
}
static cycle_t em_sti_count(struct em_sti_priv *p)
{
cycle_t ticks;
unsigned long flags;
/* the STI hardware buffers the 48-bit count, but to
* break it out into two 32-bit access the registers
* must be accessed in a certain order.
* Always read STI_COUNT_H before STI_COUNT_L.
*/
raw_spin_lock_irqsave(&p->lock, flags);
ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
ticks |= em_sti_read(p, STI_COUNT_L);
raw_spin_unlock_irqrestore(&p->lock, flags);
return ticks;
}
static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next)
{
unsigned long flags;
raw_spin_lock_irqsave(&p->lock, flags);
/* mask compare A interrupt */
em_sti_write(p, STI_INTENCLR, 1);
/* update compare A value */
em_sti_write(p, STI_COMPA_H, next >> 32);
em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
/* clear compare A interrupt source */
em_sti_write(p, STI_INTFFCLR, 1);
/* unmask compare A interrupt */
em_sti_write(p, STI_INTENSET, 1);
raw_spin_unlock_irqrestore(&p->lock, flags);
return next;
}
static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
{
struct em_sti_priv *p = dev_id;
p->ced.event_handler(&p->ced);
return IRQ_HANDLED;
}
static int em_sti_start(struct em_sti_priv *p, unsigned int user)
{
unsigned long flags;
int used_before;
int ret = 0;
raw_spin_lock_irqsave(&p->lock, flags);
used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
if (!used_before)
ret = em_sti_enable(p);
if (!ret)
p->active[user] = 1;
raw_spin_unlock_irqrestore(&p->lock, flags);
return ret;
}
static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
{
unsigned long flags;
int used_before, used_after;
raw_spin_lock_irqsave(&p->lock, flags);
used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
p->active[user] = 0;
used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
if (used_before && !used_after)
em_sti_disable(p);
raw_spin_unlock_irqrestore(&p->lock, flags);
}
static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
{
return container_of(cs, struct em_sti_priv, cs);
}
static cycle_t em_sti_clocksource_read(struct clocksource *cs)
{
return em_sti_count(cs_to_em_sti(cs));
}
static int em_sti_clocksource_enable(struct clocksource *cs)
{
int ret;
struct em_sti_priv *p = cs_to_em_sti(cs);
ret = em_sti_start(p, USER_CLOCKSOURCE);
if (!ret)
__clocksource_update_freq_hz(cs, p->rate);
return ret;
}
static void em_sti_clocksource_disable(struct clocksource *cs)
{
em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
}
static void em_sti_clocksource_resume(struct clocksource *cs)
{
em_sti_clocksource_enable(cs);
}
static int em_sti_register_clocksource(struct em_sti_priv *p)
{
struct clocksource *cs = &p->cs;
cs->name = dev_name(&p->pdev->dev);
cs->rating = 200;
cs->read = em_sti_clocksource_read;
cs->enable = em_sti_clocksource_enable;
cs->disable = em_sti_clocksource_disable;
cs->suspend = em_sti_clocksource_disable;
cs->resume = em_sti_clocksource_resume;
cs->mask = CLOCKSOURCE_MASK(48);
cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
dev_info(&p->pdev->dev, "used as clock source\n");
/* Register with dummy 1 Hz value, gets updated in ->enable() */
clocksource_register_hz(cs, 1);
return 0;
}
static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
{
return container_of(ced, struct em_sti_priv, ced);
}
static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
{
struct em_sti_priv *p = ced_to_em_sti(ced);
em_sti_stop(p, USER_CLOCKEVENT);
return 0;
}
static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
{
struct em_sti_priv *p = ced_to_em_sti(ced);
dev_info(&p->pdev->dev, "used for oneshot clock events\n");
em_sti_start(p, USER_CLOCKEVENT);
clockevents_config(&p->ced, p->rate);
return 0;
}
static int em_sti_clock_event_next(unsigned long delta,
struct clock_event_device *ced)
{
struct em_sti_priv *p = ced_to_em_sti(ced);
cycle_t next;
int safe;
next = em_sti_set_next(p, em_sti_count(p) + delta);
safe = em_sti_count(p) < (next - 1);
return !safe;
}
static void em_sti_register_clockevent(struct em_sti_priv *p)
{
struct clock_event_device *ced = &p->ced;
ced->name = dev_name(&p->pdev->dev);
ced->features = CLOCK_EVT_FEAT_ONESHOT;
ced->rating = 200;
ced->cpumask = cpu_possible_mask;
ced->set_next_event = em_sti_clock_event_next;
ced->set_state_shutdown = em_sti_clock_event_shutdown;
ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
dev_info(&p->pdev->dev, "used for clock events\n");
/* Register with dummy 1 Hz value, gets updated in ->set_state_oneshot() */
clockevents_config_and_register(ced, 1, 2, 0xffffffff);
}
static int em_sti_probe(struct platform_device *pdev)
{
struct em_sti_priv *p;
struct resource *res;
int irq;
p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
if (p == NULL)
return -ENOMEM;
p->pdev = pdev;
platform_set_drvdata(pdev, p);
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "failed to get irq\n");
return -EINVAL;
}
/* map memory, let base point to the STI instance */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
p->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(p->base))
return PTR_ERR(p->base);
/* get hold of clock */
p->clk = devm_clk_get(&pdev->dev, "sclk");
if (IS_ERR(p->clk)) {
dev_err(&pdev->dev, "cannot get clock\n");
return PTR_ERR(p->clk);
}
if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
dev_name(&pdev->dev), p)) {
dev_err(&pdev->dev, "failed to request low IRQ\n");
return -ENOENT;
}
raw_spin_lock_init(&p->lock);
em_sti_register_clockevent(p);
em_sti_register_clocksource(p);
return 0;
}
static int em_sti_remove(struct platform_device *pdev)
{
return -EBUSY; /* cannot unregister clockevent and clocksource */
}
static const struct of_device_id em_sti_dt_ids[] = {
{ .compatible = "renesas,em-sti", },
{},
};
MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
static struct platform_driver em_sti_device_driver = {
.probe = em_sti_probe,
.remove = em_sti_remove,
.driver = {
.name = "em_sti",
.of_match_table = em_sti_dt_ids,
}
};
static int __init em_sti_init(void)
{
return platform_driver_register(&em_sti_device_driver);
}
static void __exit em_sti_exit(void)
{
platform_driver_unregister(&em_sti_device_driver);
}
subsys_initcall(em_sti_init);
module_exit(em_sti_exit);
MODULE_AUTHOR("Magnus Damm");
MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
MODULE_LICENSE("GPL v2");