linux/drivers/clocksource/samsung_pwm_timer.c

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/*
* Copyright (c) 2011 Samsung Electronics Co., Ltd.
* http://www.samsung.com/
*
* samsung - Common hr-timer support (s3c and s5p)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sched_clock.h>
#include <clocksource/samsung_pwm.h>
/*
* Clocksource driver
*/
#define REG_TCFG0 0x00
#define REG_TCFG1 0x04
#define REG_TCON 0x08
#define REG_TINT_CSTAT 0x44
#define REG_TCNTB(chan) (0x0c + 12 * (chan))
#define REG_TCMPB(chan) (0x10 + 12 * (chan))
#define TCFG0_PRESCALER_MASK 0xff
#define TCFG0_PRESCALER1_SHIFT 8
#define TCFG1_SHIFT(x) ((x) * 4)
#define TCFG1_MUX_MASK 0xf
/*
* Each channel occupies 4 bits in TCON register, but there is a gap of 4
* bits (one channel) after channel 0, so channels have different numbering
* when accessing TCON register.
*
* In addition, the location of autoreload bit for channel 4 (TCON channel 5)
* in its set of bits is 2 as opposed to 3 for other channels.
*/
#define TCON_START(chan) (1 << (4 * (chan) + 0))
#define TCON_MANUALUPDATE(chan) (1 << (4 * (chan) + 1))
#define TCON_INVERT(chan) (1 << (4 * (chan) + 2))
#define _TCON_AUTORELOAD(chan) (1 << (4 * (chan) + 3))
#define _TCON_AUTORELOAD4(chan) (1 << (4 * (chan) + 2))
#define TCON_AUTORELOAD(chan) \
((chan < 5) ? _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan))
DEFINE_SPINLOCK(samsung_pwm_lock);
EXPORT_SYMBOL(samsung_pwm_lock);
struct samsung_pwm_clocksource {
void __iomem *base;
void __iomem *source_reg;
unsigned int irq[SAMSUNG_PWM_NUM];
struct samsung_pwm_variant variant;
struct clk *timerclk;
unsigned int event_id;
unsigned int source_id;
unsigned int tcnt_max;
unsigned int tscaler_div;
unsigned int tdiv;
unsigned long clock_count_per_tick;
};
static struct samsung_pwm_clocksource pwm;
static void samsung_timer_set_prescale(unsigned int channel, u16 prescale)
{
unsigned long flags;
u8 shift = 0;
u32 reg;
if (channel >= 2)
shift = TCFG0_PRESCALER1_SHIFT;
spin_lock_irqsave(&samsung_pwm_lock, flags);
reg = readl(pwm.base + REG_TCFG0);
reg &= ~(TCFG0_PRESCALER_MASK << shift);
reg |= (prescale - 1) << shift;
writel(reg, pwm.base + REG_TCFG0);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static void samsung_timer_set_divisor(unsigned int channel, u8 divisor)
{
u8 shift = TCFG1_SHIFT(channel);
unsigned long flags;
u32 reg;
u8 bits;
bits = (fls(divisor) - 1) - pwm.variant.div_base;
spin_lock_irqsave(&samsung_pwm_lock, flags);
reg = readl(pwm.base + REG_TCFG1);
reg &= ~(TCFG1_MUX_MASK << shift);
reg |= bits << shift;
writel(reg, pwm.base + REG_TCFG1);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static void samsung_time_stop(unsigned int channel)
{
unsigned long tcon;
unsigned long flags;
if (channel > 0)
++channel;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = __raw_readl(pwm.base + REG_TCON);
tcon &= ~TCON_START(channel);
__raw_writel(tcon, pwm.base + REG_TCON);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
{
unsigned long tcon;
unsigned long flags;
unsigned int tcon_chan = channel;
if (tcon_chan > 0)
++tcon_chan;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = __raw_readl(pwm.base + REG_TCON);
tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
tcon |= TCON_MANUALUPDATE(tcon_chan);
__raw_writel(tcnt, pwm.base + REG_TCNTB(channel));
__raw_writel(tcnt, pwm.base + REG_TCMPB(channel));
__raw_writel(tcon, pwm.base + REG_TCON);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static void samsung_time_start(unsigned int channel, bool periodic)
{
unsigned long tcon;
unsigned long flags;
if (channel > 0)
++channel;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = __raw_readl(pwm.base + REG_TCON);
tcon &= ~TCON_MANUALUPDATE(channel);
tcon |= TCON_START(channel);
if (periodic)
tcon |= TCON_AUTORELOAD(channel);
else
tcon &= ~TCON_AUTORELOAD(channel);
__raw_writel(tcon, pwm.base + REG_TCON);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static int samsung_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
/*
* This check is needed to account for internal rounding
* errors inside clockevents core, which might result in
* passing cycles = 0, which in turn would not generate any
* timer interrupt and hang the system.
*
* Another solution would be to set up the clockevent device
* with min_delta = 2, but this would unnecessarily increase
* the minimum sleep period.
*/
if (!cycles)
cycles = 1;
samsung_time_setup(pwm.event_id, cycles);
samsung_time_start(pwm.event_id, false);
return 0;
}
static void samsung_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
samsung_time_stop(pwm.event_id);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick - 1);
samsung_time_start(pwm.event_id, true);
break;
case CLOCK_EVT_MODE_ONESHOT:
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_RESUME:
break;
}
}
static void samsung_clockevent_resume(struct clock_event_device *cev)
{
samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);
if (pwm.variant.has_tint_cstat) {
u32 mask = (1 << pwm.event_id);
writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
}
}
static struct clock_event_device time_event_device = {
.name = "samsung_event_timer",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.rating = 200,
.set_next_event = samsung_set_next_event,
.set_mode = samsung_set_mode,
.resume = samsung_clockevent_resume,
};
static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
if (pwm.variant.has_tint_cstat) {
u32 mask = (1 << pwm.event_id);
writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
}
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction samsung_clock_event_irq = {
.name = "samsung_time_irq",
.flags = IRQF_TIMER | IRQF_IRQPOLL,
.handler = samsung_clock_event_isr,
.dev_id = &time_event_device,
};
static void __init samsung_clockevent_init(void)
{
unsigned long pclk;
unsigned long clock_rate;
unsigned int irq_number;
pclk = clk_get_rate(pwm.timerclk);
samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);
clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
pwm.clock_count_per_tick = clock_rate / HZ;
time_event_device.cpumask = cpumask_of(0);
clockevents_config_and_register(&time_event_device,
clock_rate, 1, pwm.tcnt_max);
irq_number = pwm.irq[pwm.event_id];
setup_irq(irq_number, &samsung_clock_event_irq);
if (pwm.variant.has_tint_cstat) {
u32 mask = (1 << pwm.event_id);
writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
}
}
static void samsung_clocksource_suspend(struct clocksource *cs)
{
samsung_time_stop(pwm.source_id);
}
static void samsung_clocksource_resume(struct clocksource *cs)
{
samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);
samsung_time_setup(pwm.source_id, pwm.tcnt_max);
samsung_time_start(pwm.source_id, true);
}
static cycle_t samsung_clocksource_read(struct clocksource *c)
{
return ~readl_relaxed(pwm.source_reg);
}
static struct clocksource samsung_clocksource = {
.name = "samsung_clocksource_timer",
.rating = 250,
.read = samsung_clocksource_read,
.suspend = samsung_clocksource_suspend,
.resume = samsung_clocksource_resume,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Override the global weak sched_clock symbol with this
* local implementation which uses the clocksource to get some
* better resolution when scheduling the kernel. We accept that
* this wraps around for now, since it is just a relative time
* stamp. (Inspired by U300 implementation.)
*/
static u64 notrace samsung_read_sched_clock(void)
{
return samsung_clocksource_read(NULL);
}
static void __init samsung_clocksource_init(void)
{
unsigned long pclk;
unsigned long clock_rate;
int ret;
pclk = clk_get_rate(pwm.timerclk);
samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);
clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
samsung_time_setup(pwm.source_id, pwm.tcnt_max);
samsung_time_start(pwm.source_id, true);
if (pwm.source_id == 4)
pwm.source_reg = pwm.base + 0x40;
else
pwm.source_reg = pwm.base + pwm.source_id * 0x0c + 0x14;
sched_clock_register(samsung_read_sched_clock,
pwm.variant.bits, clock_rate);
samsung_clocksource.mask = CLOCKSOURCE_MASK(pwm.variant.bits);
ret = clocksource_register_hz(&samsung_clocksource, clock_rate);
if (ret)
panic("samsung_clocksource_timer: can't register clocksource\n");
}
static void __init samsung_timer_resources(void)
{
clk_prepare_enable(pwm.timerclk);
pwm.tcnt_max = (1UL << pwm.variant.bits) - 1;
if (pwm.variant.bits == 16) {
pwm.tscaler_div = 25;
pwm.tdiv = 2;
} else {
pwm.tscaler_div = 2;
pwm.tdiv = 1;
}
}
/*
* PWM master driver
*/
static void __init _samsung_pwm_clocksource_init(void)
{
u8 mask;
int channel;
mask = ~pwm.variant.output_mask & ((1 << SAMSUNG_PWM_NUM) - 1);
channel = fls(mask) - 1;
if (channel < 0)
panic("failed to find PWM channel for clocksource");
pwm.source_id = channel;
mask &= ~(1 << channel);
channel = fls(mask) - 1;
if (channel < 0)
panic("failed to find PWM channel for clock event");
pwm.event_id = channel;
samsung_timer_resources();
samsung_clockevent_init();
samsung_clocksource_init();
}
void __init samsung_pwm_clocksource_init(void __iomem *base,
unsigned int *irqs, struct samsung_pwm_variant *variant)
{
pwm.base = base;
memcpy(&pwm.variant, variant, sizeof(pwm.variant));
memcpy(pwm.irq, irqs, SAMSUNG_PWM_NUM * sizeof(*irqs));
pwm.timerclk = clk_get(NULL, "timers");
if (IS_ERR(pwm.timerclk))
panic("failed to get timers clock for timer");
_samsung_pwm_clocksource_init();
}
#ifdef CONFIG_CLKSRC_OF
static void __init samsung_pwm_alloc(struct device_node *np,
const struct samsung_pwm_variant *variant)
{
struct property *prop;
const __be32 *cur;
u32 val;
int i;
memcpy(&pwm.variant, variant, sizeof(pwm.variant));
for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
pwm.irq[i] = irq_of_parse_and_map(np, i);
of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
if (val >= SAMSUNG_PWM_NUM) {
pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
__func__);
continue;
}
pwm.variant.output_mask |= 1 << val;
}
pwm.base = of_iomap(np, 0);
if (!pwm.base) {
pr_err("%s: failed to map PWM registers\n", __func__);
return;
}
pwm.timerclk = of_clk_get_by_name(np, "timers");
if (IS_ERR(pwm.timerclk))
panic("failed to get timers clock for timer");
_samsung_pwm_clocksource_init();
}
static const struct samsung_pwm_variant s3c24xx_variant = {
.bits = 16,
.div_base = 1,
.has_tint_cstat = false,
.tclk_mask = (1 << 4),
};
static void __init s3c2410_pwm_clocksource_init(struct device_node *np)
{
samsung_pwm_alloc(np, &s3c24xx_variant);
}
CLOCKSOURCE_OF_DECLARE(s3c2410_pwm, "samsung,s3c2410-pwm", s3c2410_pwm_clocksource_init);
static const struct samsung_pwm_variant s3c64xx_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = (1 << 7) | (1 << 6) | (1 << 5),
};
static void __init s3c64xx_pwm_clocksource_init(struct device_node *np)
{
samsung_pwm_alloc(np, &s3c64xx_variant);
}
CLOCKSOURCE_OF_DECLARE(s3c6400_pwm, "samsung,s3c6400-pwm", s3c64xx_pwm_clocksource_init);
static const struct samsung_pwm_variant s5p64x0_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = 0,
};
static void __init s5p64x0_pwm_clocksource_init(struct device_node *np)
{
samsung_pwm_alloc(np, &s5p64x0_variant);
}
CLOCKSOURCE_OF_DECLARE(s5p6440_pwm, "samsung,s5p6440-pwm", s5p64x0_pwm_clocksource_init);
static const struct samsung_pwm_variant s5p_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = (1 << 5),
};
static void __init s5p_pwm_clocksource_init(struct device_node *np)
{
samsung_pwm_alloc(np, &s5p_variant);
}
CLOCKSOURCE_OF_DECLARE(s5pc100_pwm, "samsung,s5pc100-pwm", s5p_pwm_clocksource_init);
#endif