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/*
* linux/arch/arm/plat-nomadik/timer.c
*
* Copyright (C) 2008 STMicroelectronics
* Copyright (C) 2010 Alessandro Rubini
* Copyright (C) 2010 Linus Walleij for ST-Ericsson
*
* 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/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/jiffies.h>
#include <linux/err.h>
#include <asm/mach/time.h>
#include <asm/sched_clock.h>
/*
* Guaranteed runtime conversion range in seconds for
* the clocksource and clockevent.
*/
#define MTU_MIN_RANGE 4
/*
* The MTU device hosts four different counters, with 4 set of
* registers. These are register names.
*/
#define MTU_IMSC 0x00 /* Interrupt mask set/clear */
#define MTU_RIS 0x04 /* Raw interrupt status */
#define MTU_MIS 0x08 /* Masked interrupt status */
#define MTU_ICR 0x0C /* Interrupt clear register */
/* per-timer registers take 0..3 as argument */
#define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */
#define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */
#define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */
#define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */
/* bits for the control register */
#define MTU_CRn_ENA 0x80
#define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */
#define MTU_CRn_PRESCALE_MASK 0x0c
#define MTU_CRn_PRESCALE_1 0x00
#define MTU_CRn_PRESCALE_16 0x04
#define MTU_CRn_PRESCALE_256 0x08
#define MTU_CRn_32BITS 0x02
#define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/
/* Other registers are usual amba/primecell registers, currently not used */
#define MTU_ITCR 0xff0
#define MTU_ITOP 0xff4
#define MTU_PERIPH_ID0 0xfe0
#define MTU_PERIPH_ID1 0xfe4
#define MTU_PERIPH_ID2 0xfe8
#define MTU_PERIPH_ID3 0xfeC
#define MTU_PCELL0 0xff0
#define MTU_PCELL1 0xff4
#define MTU_PCELL2 0xff8
#define MTU_PCELL3 0xffC
static bool clkevt_periodic;
static u32 clk_prescale;
static u32 nmdk_cycle; /* write-once */
void __iomem *mtu_base; /* Assigned by machine code */
#ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK
/*
* Override the global weak sched_clock symbol with this
* local implementation which uses the clocksource to get some
* better resolution when scheduling the kernel.
*/
static u32 notrace nomadik_read_sched_clock(void)
{
if (unlikely(!mtu_base))
return 0;
return -readl(mtu_base + MTU_VAL(0));
}
#endif
/* Clockevent device: use one-shot mode */
static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
{
writel(1 << 1, mtu_base + MTU_IMSC);
writel(evt, mtu_base + MTU_LR(1));
/* Load highest value, enable device, enable interrupts */
writel(MTU_CRn_ONESHOT | clk_prescale |
MTU_CRn_32BITS | MTU_CRn_ENA,
mtu_base + MTU_CR(1));
return 0;
}
void nmdk_clkevt_reset(void)
{
if (clkevt_periodic) {
/* Timer: configure load and background-load, and fire it up */
writel(nmdk_cycle, mtu_base + MTU_LR(1));
writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
writel(MTU_CRn_PERIODIC | clk_prescale |
MTU_CRn_32BITS | MTU_CRn_ENA,
mtu_base + MTU_CR(1));
writel(1 << 1, mtu_base + MTU_IMSC);
} else {
/* Generate an interrupt to start the clockevent again */
(void) nmdk_clkevt_next(nmdk_cycle, NULL);
}
}
static void nmdk_clkevt_mode(enum clock_event_mode mode,
struct clock_event_device *dev)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
clkevt_periodic = true;
nmdk_clkevt_reset();
break;
case CLOCK_EVT_MODE_ONESHOT:
clkevt_periodic = false;
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
writel(0, mtu_base + MTU_IMSC);
/* disable timer */
writel(0, mtu_base + MTU_CR(1));
/* load some high default value */
writel(0xffffffff, mtu_base + MTU_LR(1));
break;
case CLOCK_EVT_MODE_RESUME:
break;
}
}
static struct clock_event_device nmdk_clkevt = {
.name = "mtu_1",
.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
.rating = 200,
.set_mode = nmdk_clkevt_mode,
.set_next_event = nmdk_clkevt_next,
};
/*
* IRQ Handler for timer 1 of the MTU block.
*/
static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evdev = dev_id;
writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
evdev->event_handler(evdev);
return IRQ_HANDLED;
}
static struct irqaction nmdk_timer_irq = {
.name = "Nomadik Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = nmdk_timer_interrupt,
.dev_id = &nmdk_clkevt,
};
void nmdk_clksrc_reset(void)
{
/* Disable */
writel(0, mtu_base + MTU_CR(0));
/* ClockSource: configure load and background-load, and fire it up */
writel(nmdk_cycle, mtu_base + MTU_LR(0));
writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
mtu_base + MTU_CR(0));
}
void __init nmdk_timer_init(void)
{
unsigned long rate;
struct clk *clk0;
clk0 = clk_get_sys("mtu0", NULL);
BUG_ON(IS_ERR(clk0));
clk_enable(clk0);
/*
* Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
* for ux500.
* Use a divide-by-16 counter if the tick rate is more than 32MHz.
* At 32 MHz, the timer (with 32 bit counter) can be programmed
* to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
* with 16 gives too low timer resolution.
*/
rate = clk_get_rate(clk0);
if (rate > 32000000) {
rate /= 16;
clk_prescale = MTU_CRn_PRESCALE_16;
} else {
clk_prescale = MTU_CRn_PRESCALE_1;
}
nmdk_cycle = (rate + HZ/2) / HZ;
/* Timer 0 is the free running clocksource */
nmdk_clksrc_reset();
if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
rate, 200, 32, clocksource_mmio_readl_down))
pr_err("timer: failed to initialize clock source %s\n",
"mtu_0");
#ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK
setup_sched_clock(nomadik_read_sched_clock, 32, rate);
#endif
/* Timer 1 is used for events */
clockevents_calc_mult_shift(&nmdk_clkevt, rate, MTU_MIN_RANGE);
nmdk_clkevt.max_delta_ns =
clockevent_delta2ns(0xffffffff, &nmdk_clkevt);
nmdk_clkevt.min_delta_ns =
clockevent_delta2ns(0x00000002, &nmdk_clkevt);
nmdk_clkevt.cpumask = cpumask_of(0);
/* Register irq and clockevents */
setup_irq(IRQ_MTU0, &nmdk_timer_irq);
clockevents_register_device(&nmdk_clkevt);
}
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