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PL286/kernel-3.18/drivers/clocksource/time-armada-370-xp.c

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/*
* Marvell Armada 370/XP SoC timer handling.
*
* Copyright (C) 2012 Marvell
*
* Lior Amsalem <alior@marvell.com>
* Gregory CLEMENT <gregory.clement@free-electrons.com>
* Thomas Petazzoni <thomas.petazzoni@free-electrons.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.
*
* Timer 0 is used as free-running clocksource, while timer 1 is
* used as clock_event_device.
*
* ---
* Clocksource driver for Armada 370 and Armada XP SoC.
* This driver implements one compatible string for each SoC, given
* each has its own characteristics:
*
* * Armada 370 has no 25 MHz fixed timer.
*
* * Armada XP cannot work properly without such 25 MHz fixed timer as
* doing otherwise leads to using a clocksource whose frequency varies
* when doing cpufreq frequency changes.
*
* See Documentation/devicetree/bindings/timer/marvell,armada-370-xp-timer.txt
*/
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/timer.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/sched_clock.h>
#include <linux/percpu.h>
/*
* Timer block registers.
*/
#define TIMER_CTRL_OFF 0x0000
#define TIMER0_EN BIT(0)
#define TIMER0_RELOAD_EN BIT(1)
#define TIMER0_25MHZ BIT(11)
#define TIMER0_DIV(div) ((div) << 19)
#define TIMER1_EN BIT(2)
#define TIMER1_RELOAD_EN BIT(3)
#define TIMER1_25MHZ BIT(12)
#define TIMER1_DIV(div) ((div) << 22)
#define TIMER_EVENTS_STATUS 0x0004
#define TIMER0_CLR_MASK (~0x1)
#define TIMER1_CLR_MASK (~0x100)
#define TIMER0_RELOAD_OFF 0x0010
#define TIMER0_VAL_OFF 0x0014
#define TIMER1_RELOAD_OFF 0x0018
#define TIMER1_VAL_OFF 0x001c
#define LCL_TIMER_EVENTS_STATUS 0x0028
/* Global timers are connected to the coherency fabric clock, and the
below divider reduces their incrementing frequency. */
#define TIMER_DIVIDER_SHIFT 5
#define TIMER_DIVIDER (1 << TIMER_DIVIDER_SHIFT)
/*
* SoC-specific data.
*/
static void __iomem *timer_base, *local_base;
static unsigned int timer_clk;
static bool timer25Mhz = true;
static u32 enable_mask;
/*
* Number of timer ticks per jiffy.
*/
static u32 ticks_per_jiffy;
static struct clock_event_device __percpu *armada_370_xp_evt;
static void local_timer_ctrl_clrset(u32 clr, u32 set)
{
writel((readl(local_base + TIMER_CTRL_OFF) & ~clr) | set,
local_base + TIMER_CTRL_OFF);
}
static u64 notrace armada_370_xp_read_sched_clock(void)
{
return ~readl(timer_base + TIMER0_VAL_OFF);
}
/*
* Clockevent handling.
*/
static int
armada_370_xp_clkevt_next_event(unsigned long delta,
struct clock_event_device *dev)
{
/*
* Clear clockevent timer interrupt.
*/
writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
/*
* Setup new clockevent timer value.
*/
writel(delta, local_base + TIMER0_VAL_OFF);
/*
* Enable the timer.
*/
local_timer_ctrl_clrset(TIMER0_RELOAD_EN, enable_mask);
return 0;
}
static void
armada_370_xp_clkevt_mode(enum clock_event_mode mode,
struct clock_event_device *dev)
{
if (mode == CLOCK_EVT_MODE_PERIODIC) {
/*
* Setup timer to fire at 1/HZ intervals.
*/
writel(ticks_per_jiffy - 1, local_base + TIMER0_RELOAD_OFF);
writel(ticks_per_jiffy - 1, local_base + TIMER0_VAL_OFF);
/*
* Enable timer.
*/
local_timer_ctrl_clrset(0, TIMER0_RELOAD_EN | enable_mask);
} else {
/*
* Disable timer.
*/
local_timer_ctrl_clrset(TIMER0_EN, 0);
/*
* ACK pending timer interrupt.
*/
writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
}
}
static int armada_370_xp_clkevt_irq;
static irqreturn_t armada_370_xp_timer_interrupt(int irq, void *dev_id)
{
/*
* ACK timer interrupt and call event handler.
*/
struct clock_event_device *evt = dev_id;
writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
evt->event_handler(evt);
return IRQ_HANDLED;
}
/*
* Setup the local clock events for a CPU.
*/
static int armada_370_xp_timer_setup(struct clock_event_device *evt)
{
u32 clr = 0, set = 0;
int cpu = smp_processor_id();
if (timer25Mhz)
set = TIMER0_25MHZ;
else
clr = TIMER0_25MHZ;
local_timer_ctrl_clrset(clr, set);
evt->name = "armada_370_xp_per_cpu_tick",
evt->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_PERIODIC;
evt->shift = 32,
evt->rating = 300,
evt->set_next_event = armada_370_xp_clkevt_next_event,
evt->set_mode = armada_370_xp_clkevt_mode,
evt->irq = armada_370_xp_clkevt_irq;
evt->cpumask = cpumask_of(cpu);
clockevents_config_and_register(evt, timer_clk, 1, 0xfffffffe);
enable_percpu_irq(evt->irq, 0);
return 0;
}
static void armada_370_xp_timer_stop(struct clock_event_device *evt)
{
evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
disable_percpu_irq(evt->irq);
}
static int armada_370_xp_timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
/*
* Grab cpu pointer in each case to avoid spurious
* preemptible warnings
*/
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_STARTING:
armada_370_xp_timer_setup(this_cpu_ptr(armada_370_xp_evt));
break;
case CPU_DYING:
armada_370_xp_timer_stop(this_cpu_ptr(armada_370_xp_evt));
break;
}
return NOTIFY_OK;
}
static struct notifier_block armada_370_xp_timer_cpu_nb = {
.notifier_call = armada_370_xp_timer_cpu_notify,
};
static void __init armada_370_xp_timer_common_init(struct device_node *np)
{
u32 clr = 0, set = 0;
int res;
timer_base = of_iomap(np, 0);
WARN_ON(!timer_base);
local_base = of_iomap(np, 1);
if (timer25Mhz) {
set = TIMER0_25MHZ;
enable_mask = TIMER0_EN;
} else {
clr = TIMER0_25MHZ;
enable_mask = TIMER0_EN | TIMER0_DIV(TIMER_DIVIDER_SHIFT);
}
atomic_io_modify(timer_base + TIMER_CTRL_OFF, clr | set, set);
local_timer_ctrl_clrset(clr, set);
/*
* We use timer 0 as clocksource, and private(local) timer 0
* for clockevents
*/
armada_370_xp_clkevt_irq = irq_of_parse_and_map(np, 4);
ticks_per_jiffy = (timer_clk + HZ / 2) / HZ;
/*
* Setup free-running clocksource timer (interrupts
* disabled).
*/
writel(0xffffffff, timer_base + TIMER0_VAL_OFF);
writel(0xffffffff, timer_base + TIMER0_RELOAD_OFF);
atomic_io_modify(timer_base + TIMER_CTRL_OFF,
TIMER0_RELOAD_EN | enable_mask,
TIMER0_RELOAD_EN | enable_mask);
/*
* Set scale and timer for sched_clock.
*/
sched_clock_register(armada_370_xp_read_sched_clock, 32, timer_clk);
clocksource_mmio_init(timer_base + TIMER0_VAL_OFF,
"armada_370_xp_clocksource",
timer_clk, 300, 32, clocksource_mmio_readl_down);
register_cpu_notifier(&armada_370_xp_timer_cpu_nb);
armada_370_xp_evt = alloc_percpu(struct clock_event_device);
/*
* Setup clockevent timer (interrupt-driven).
*/
res = request_percpu_irq(armada_370_xp_clkevt_irq,
armada_370_xp_timer_interrupt,
"armada_370_xp_per_cpu_tick",
armada_370_xp_evt);
/* Immediately configure the timer on the boot CPU */
if (!res)
armada_370_xp_timer_setup(this_cpu_ptr(armada_370_xp_evt));
}
static void __init armada_xp_timer_init(struct device_node *np)
{
struct clk *clk = of_clk_get_by_name(np, "fixed");
/* The 25Mhz fixed clock is mandatory, and must always be available */
BUG_ON(IS_ERR(clk));
timer_clk = clk_get_rate(clk);
armada_370_xp_timer_common_init(np);
}
CLOCKSOURCE_OF_DECLARE(armada_xp, "marvell,armada-xp-timer",
armada_xp_timer_init);
static void __init armada_370_timer_init(struct device_node *np)
{
struct clk *clk = of_clk_get(np, 0);
BUG_ON(IS_ERR(clk));
timer_clk = clk_get_rate(clk) / TIMER_DIVIDER;
timer25Mhz = false;
armada_370_xp_timer_common_init(np);
}
CLOCKSOURCE_OF_DECLARE(armada_370, "marvell,armada-370-timer",
armada_370_timer_init);