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/*
* Allwinner A1X SoCs timer handling.
*
* Copyright (C) 2012 Maxime Ripard
*
* Maxime Ripard <maxime.ripard@free-electrons.com>
*
* Based on code from
* Allwinner Technology Co., Ltd. <www.allwinnertech.com>
* Benn Huang <benn@allwinnertech.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/sched_clock.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#define TIMER_IRQ_EN_REG 0x00
#define TIMER_IRQ_EN(val) BIT(val)
#define TIMER_IRQ_ST_REG 0x04
#define TIMER_CTL_REG(val) (0x10 * val + 0x10)
#define TIMER_CTL_ENABLE BIT(0)
#define TIMER_CTL_RELOAD BIT(1)
#define TIMER_CTL_CLK_SRC(val) (((val) & 0x3) << 2)
#define TIMER_CTL_CLK_SRC_OSC24M (1)
#define TIMER_CTL_CLK_PRES(val) (((val) & 0x7) << 4)
#define TIMER_CTL_ONESHOT BIT(7)
#define TIMER_INTVAL_REG(val) (0x10 * (val) + 0x14)
#define TIMER_CNTVAL_REG(val) (0x10 * (val) + 0x18)
#define TIMER_SYNC_TICKS 3
static void __iomem *timer_base;
static u32 ticks_per_jiffy;
/*
* When we disable a timer, we need to wait at least for 2 cycles of
* the timer source clock. We will use for that the clocksource timer
* that is already setup and runs at the same frequency than the other
* timers, and we never will be disabled.
*/
static void sun4i_clkevt_sync(void)
{
u32 old = readl(timer_base + TIMER_CNTVAL_REG(1));
while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
cpu_relax();
}
static void sun4i_clkevt_time_stop(u8 timer)
{
u32 val = readl(timer_base + TIMER_CTL_REG(timer));
writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
sun4i_clkevt_sync();
}
static void sun4i_clkevt_time_setup(u8 timer, unsigned long delay)
{
writel(delay, timer_base + TIMER_INTVAL_REG(timer));
}
static void sun4i_clkevt_time_start(u8 timer, bool periodic)
{
u32 val = readl(timer_base + TIMER_CTL_REG(timer));
if (periodic)
val &= ~TIMER_CTL_ONESHOT;
else
val |= TIMER_CTL_ONESHOT;
writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
timer_base + TIMER_CTL_REG(timer));
}
static void sun4i_clkevt_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
sun4i_clkevt_time_stop(0);
sun4i_clkevt_time_setup(0, ticks_per_jiffy);
sun4i_clkevt_time_start(0, true);
break;
case CLOCK_EVT_MODE_ONESHOT:
sun4i_clkevt_time_stop(0);
sun4i_clkevt_time_start(0, false);
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
default:
sun4i_clkevt_time_stop(0);
break;
}
}
static int sun4i_clkevt_next_event(unsigned long evt,
struct clock_event_device *unused)
{
sun4i_clkevt_time_stop(0);
sun4i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
sun4i_clkevt_time_start(0, false);
return 0;
}
static struct clock_event_device sun4i_clockevent = {
.name = "sun4i_tick",
.rating = 300,
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_mode = sun4i_clkevt_mode,
.set_next_event = sun4i_clkevt_next_event,
};
static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = (struct clock_event_device *)dev_id;
writel(0x1, timer_base + TIMER_IRQ_ST_REG);
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction sun4i_timer_irq = {
.name = "sun4i_timer0",
.flags = IRQF_TIMER | IRQF_IRQPOLL,
.handler = sun4i_timer_interrupt,
.dev_id = &sun4i_clockevent,
};
static u32 sun4i_timer_sched_read(void)
{
return ~readl(timer_base + TIMER_CNTVAL_REG(1));
}
static void __init sun4i_timer_init(struct device_node *node)
{
unsigned long rate = 0;
struct clk *clk;
int ret, irq;
u32 val;
timer_base = of_iomap(node, 0);
if (!timer_base)
panic("Can't map registers");
irq = irq_of_parse_and_map(node, 0);
if (irq <= 0)
panic("Can't parse IRQ");
clk = of_clk_get(node, 0);
if (IS_ERR(clk))
panic("Can't get timer clock");
clk_prepare_enable(clk);
rate = clk_get_rate(clk);
writel(~0, timer_base + TIMER_INTVAL_REG(1));
writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
timer_base + TIMER_CTL_REG(1));
setup_sched_clock(sun4i_timer_sched_read, 32, rate);
clocksource_mmio_init(timer_base + TIMER_CNTVAL_REG(1), node->name,
rate, 300, 32, clocksource_mmio_readl_down);
ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
timer_base + TIMER_CTL_REG(0));
/* Make sure timer is stopped before playing with interrupts */
sun4i_clkevt_time_stop(0);
ret = setup_irq(irq, &sun4i_timer_irq);
if (ret)
pr_warn("failed to setup irq %d\n", irq);
/* Enable timer0 interrupt */
val = readl(timer_base + TIMER_IRQ_EN_REG);
writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
sun4i_clockevent.cpumask = cpumask_of(0);
clockevents_config_and_register(&sun4i_clockevent, rate,
TIMER_SYNC_TICKS, 0xffffffff);
}
CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
sun4i_timer_init);
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