linux/drivers/clocksource/sh_tmu.c
Shin-ichiro KAWASAKI 6f4b67b8ff clocksource: sh_tmu: Make undefined TCOR behaviour less undefined.
Avoid undocumented vague TMU behavior when zero value is set to TCOR.

This primarily fixes up issues encountered under qemu with a zero-length
period, while the hardware itself is fairly ambivalent one way or the
other.

Signed-off-by: Shin-ichiro KAWASAKI <kawasaki@juno.dti.ne.jp>
Acked-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-06-24 21:08:11 +09:00

464 lines
11 KiB
C

/*
* SuperH Timer Support - TMU
*
* Copyright (C) 2009 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/delay.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/sh_timer.h>
struct sh_tmu_priv {
void __iomem *mapbase;
struct clk *clk;
struct irqaction irqaction;
struct platform_device *pdev;
unsigned long rate;
unsigned long periodic;
struct clock_event_device ced;
struct clocksource cs;
};
static DEFINE_SPINLOCK(sh_tmu_lock);
#define TSTR -1 /* shared register */
#define TCOR 0 /* channel register */
#define TCNT 1 /* channel register */
#define TCR 2 /* channel register */
static inline unsigned long sh_tmu_read(struct sh_tmu_priv *p, int reg_nr)
{
struct sh_timer_config *cfg = p->pdev->dev.platform_data;
void __iomem *base = p->mapbase;
unsigned long offs;
if (reg_nr == TSTR)
return ioread8(base - cfg->channel_offset);
offs = reg_nr << 2;
if (reg_nr == TCR)
return ioread16(base + offs);
else
return ioread32(base + offs);
}
static inline void sh_tmu_write(struct sh_tmu_priv *p, int reg_nr,
unsigned long value)
{
struct sh_timer_config *cfg = p->pdev->dev.platform_data;
void __iomem *base = p->mapbase;
unsigned long offs;
if (reg_nr == TSTR) {
iowrite8(value, base - cfg->channel_offset);
return;
}
offs = reg_nr << 2;
if (reg_nr == TCR)
iowrite16(value, base + offs);
else
iowrite32(value, base + offs);
}
static void sh_tmu_start_stop_ch(struct sh_tmu_priv *p, int start)
{
struct sh_timer_config *cfg = p->pdev->dev.platform_data;
unsigned long flags, value;
/* start stop register shared by multiple timer channels */
spin_lock_irqsave(&sh_tmu_lock, flags);
value = sh_tmu_read(p, TSTR);
if (start)
value |= 1 << cfg->timer_bit;
else
value &= ~(1 << cfg->timer_bit);
sh_tmu_write(p, TSTR, value);
spin_unlock_irqrestore(&sh_tmu_lock, flags);
}
static int sh_tmu_enable(struct sh_tmu_priv *p)
{
struct sh_timer_config *cfg = p->pdev->dev.platform_data;
int ret;
/* enable clock */
ret = clk_enable(p->clk);
if (ret) {
pr_err("sh_tmu: cannot enable clock \"%s\"\n", cfg->clk);
return ret;
}
/* make sure channel is disabled */
sh_tmu_start_stop_ch(p, 0);
/* maximum timeout */
sh_tmu_write(p, TCOR, 0xffffffff);
sh_tmu_write(p, TCNT, 0xffffffff);
/* configure channel to parent clock / 4, irq off */
p->rate = clk_get_rate(p->clk) / 4;
sh_tmu_write(p, TCR, 0x0000);
/* enable channel */
sh_tmu_start_stop_ch(p, 1);
return 0;
}
static void sh_tmu_disable(struct sh_tmu_priv *p)
{
/* disable channel */
sh_tmu_start_stop_ch(p, 0);
/* disable interrupts in TMU block */
sh_tmu_write(p, TCR, 0x0000);
/* stop clock */
clk_disable(p->clk);
}
static void sh_tmu_set_next(struct sh_tmu_priv *p, unsigned long delta,
int periodic)
{
/* stop timer */
sh_tmu_start_stop_ch(p, 0);
/* acknowledge interrupt */
sh_tmu_read(p, TCR);
/* enable interrupt */
sh_tmu_write(p, TCR, 0x0020);
/* reload delta value in case of periodic timer */
if (periodic)
sh_tmu_write(p, TCOR, delta);
else
sh_tmu_write(p, TCOR, 0xffffffff);
sh_tmu_write(p, TCNT, delta);
/* start timer */
sh_tmu_start_stop_ch(p, 1);
}
static irqreturn_t sh_tmu_interrupt(int irq, void *dev_id)
{
struct sh_tmu_priv *p = dev_id;
/* disable or acknowledge interrupt */
if (p->ced.mode == CLOCK_EVT_MODE_ONESHOT)
sh_tmu_write(p, TCR, 0x0000);
else
sh_tmu_write(p, TCR, 0x0020);
/* notify clockevent layer */
p->ced.event_handler(&p->ced);
return IRQ_HANDLED;
}
static struct sh_tmu_priv *cs_to_sh_tmu(struct clocksource *cs)
{
return container_of(cs, struct sh_tmu_priv, cs);
}
static cycle_t sh_tmu_clocksource_read(struct clocksource *cs)
{
struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
return sh_tmu_read(p, TCNT) ^ 0xffffffff;
}
static int sh_tmu_clocksource_enable(struct clocksource *cs)
{
struct sh_tmu_priv *p = cs_to_sh_tmu(cs);
int ret;
ret = sh_tmu_enable(p);
if (ret)
return ret;
/* TODO: calculate good shift from rate and counter bit width */
cs->shift = 10;
cs->mult = clocksource_hz2mult(p->rate, cs->shift);
return 0;
}
static void sh_tmu_clocksource_disable(struct clocksource *cs)
{
sh_tmu_disable(cs_to_sh_tmu(cs));
}
static int sh_tmu_register_clocksource(struct sh_tmu_priv *p,
char *name, unsigned long rating)
{
struct clocksource *cs = &p->cs;
cs->name = name;
cs->rating = rating;
cs->read = sh_tmu_clocksource_read;
cs->enable = sh_tmu_clocksource_enable;
cs->disable = sh_tmu_clocksource_disable;
cs->mask = CLOCKSOURCE_MASK(32);
cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
pr_info("sh_tmu: %s used as clock source\n", cs->name);
clocksource_register(cs);
return 0;
}
static struct sh_tmu_priv *ced_to_sh_tmu(struct clock_event_device *ced)
{
return container_of(ced, struct sh_tmu_priv, ced);
}
static void sh_tmu_clock_event_start(struct sh_tmu_priv *p, int periodic)
{
struct clock_event_device *ced = &p->ced;
sh_tmu_enable(p);
/* TODO: calculate good shift from rate and counter bit width */
ced->shift = 32;
ced->mult = div_sc(p->rate, NSEC_PER_SEC, ced->shift);
ced->max_delta_ns = clockevent_delta2ns(0xffffffff, ced);
ced->min_delta_ns = 5000;
if (periodic) {
p->periodic = (p->rate + HZ/2) / HZ;
sh_tmu_set_next(p, p->periodic, 1);
}
}
static void sh_tmu_clock_event_mode(enum clock_event_mode mode,
struct clock_event_device *ced)
{
struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
int disabled = 0;
/* deal with old setting first */
switch (ced->mode) {
case CLOCK_EVT_MODE_PERIODIC:
case CLOCK_EVT_MODE_ONESHOT:
sh_tmu_disable(p);
disabled = 1;
break;
default:
break;
}
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
pr_info("sh_tmu: %s used for periodic clock events\n",
ced->name);
sh_tmu_clock_event_start(p, 1);
break;
case CLOCK_EVT_MODE_ONESHOT:
pr_info("sh_tmu: %s used for oneshot clock events\n",
ced->name);
sh_tmu_clock_event_start(p, 0);
break;
case CLOCK_EVT_MODE_UNUSED:
if (!disabled)
sh_tmu_disable(p);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
default:
break;
}
}
static int sh_tmu_clock_event_next(unsigned long delta,
struct clock_event_device *ced)
{
struct sh_tmu_priv *p = ced_to_sh_tmu(ced);
BUG_ON(ced->mode != CLOCK_EVT_MODE_ONESHOT);
/* program new delta value */
sh_tmu_set_next(p, delta, 0);
return 0;
}
static void sh_tmu_register_clockevent(struct sh_tmu_priv *p,
char *name, unsigned long rating)
{
struct clock_event_device *ced = &p->ced;
int ret;
memset(ced, 0, sizeof(*ced));
ced->name = name;
ced->features = CLOCK_EVT_FEAT_PERIODIC;
ced->features |= CLOCK_EVT_FEAT_ONESHOT;
ced->rating = rating;
ced->cpumask = cpumask_of(0);
ced->set_next_event = sh_tmu_clock_event_next;
ced->set_mode = sh_tmu_clock_event_mode;
ret = setup_irq(p->irqaction.irq, &p->irqaction);
if (ret) {
pr_err("sh_tmu: failed to request irq %d\n",
p->irqaction.irq);
return;
}
pr_info("sh_tmu: %s used for clock events\n", ced->name);
clockevents_register_device(ced);
}
static int sh_tmu_register(struct sh_tmu_priv *p, char *name,
unsigned long clockevent_rating,
unsigned long clocksource_rating)
{
if (clockevent_rating)
sh_tmu_register_clockevent(p, name, clockevent_rating);
else if (clocksource_rating)
sh_tmu_register_clocksource(p, name, clocksource_rating);
return 0;
}
static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
{
struct sh_timer_config *cfg = pdev->dev.platform_data;
struct resource *res;
int irq, ret;
ret = -ENXIO;
memset(p, 0, sizeof(*p));
p->pdev = pdev;
if (!cfg) {
dev_err(&p->pdev->dev, "missing platform data\n");
goto err0;
}
platform_set_drvdata(pdev, p);
res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&p->pdev->dev, "failed to get I/O memory\n");
goto err0;
}
irq = platform_get_irq(p->pdev, 0);
if (irq < 0) {
dev_err(&p->pdev->dev, "failed to get irq\n");
goto err0;
}
/* map memory, let mapbase point to our channel */
p->mapbase = ioremap_nocache(res->start, resource_size(res));
if (p->mapbase == NULL) {
pr_err("sh_tmu: failed to remap I/O memory\n");
goto err0;
}
/* setup data for setup_irq() (too early for request_irq()) */
p->irqaction.name = cfg->name;
p->irqaction.handler = sh_tmu_interrupt;
p->irqaction.dev_id = p;
p->irqaction.irq = irq;
p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL;
/* get hold of clock */
p->clk = clk_get(&p->pdev->dev, cfg->clk);
if (IS_ERR(p->clk)) {
pr_err("sh_tmu: cannot get clock \"%s\"\n", cfg->clk);
ret = PTR_ERR(p->clk);
goto err1;
}
return sh_tmu_register(p, cfg->name,
cfg->clockevent_rating,
cfg->clocksource_rating);
err1:
iounmap(p->mapbase);
err0:
return ret;
}
static int __devinit sh_tmu_probe(struct platform_device *pdev)
{
struct sh_tmu_priv *p = platform_get_drvdata(pdev);
struct sh_timer_config *cfg = pdev->dev.platform_data;
int ret;
if (p) {
pr_info("sh_tmu: %s kept as earlytimer\n", cfg->name);
return 0;
}
p = kmalloc(sizeof(*p), GFP_KERNEL);
if (p == NULL) {
dev_err(&pdev->dev, "failed to allocate driver data\n");
return -ENOMEM;
}
ret = sh_tmu_setup(p, pdev);
if (ret) {
kfree(p);
platform_set_drvdata(pdev, NULL);
}
return ret;
}
static int __devexit sh_tmu_remove(struct platform_device *pdev)
{
return -EBUSY; /* cannot unregister clockevent and clocksource */
}
static struct platform_driver sh_tmu_device_driver = {
.probe = sh_tmu_probe,
.remove = __devexit_p(sh_tmu_remove),
.driver = {
.name = "sh_tmu",
}
};
static int __init sh_tmu_init(void)
{
return platform_driver_register(&sh_tmu_device_driver);
}
static void __exit sh_tmu_exit(void)
{
platform_driver_unregister(&sh_tmu_device_driver);
}
early_platform_init("earlytimer", &sh_tmu_device_driver);
module_init(sh_tmu_init);
module_exit(sh_tmu_exit);
MODULE_AUTHOR("Magnus Damm");
MODULE_DESCRIPTION("SuperH TMU Timer Driver");
MODULE_LICENSE("GPL v2");