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kernel/drivers/clocksource/timer-fttmr010.c
Linus Walleij 28e71e2fe8 clocksource/drivers/fttmr010: Refactor to handle clock 
The plain Faraday FTTMR010 timer needs a clock to figure out its
tick rate, and the gemini reads it directly from the system
controller set-up. Split the init function and add two paths for
the two compatible-strings. We only support clocking using PCLK
because of lack of documentation on how EXTCLK works.

The Gemini still works like before, but we can also support a
generic, clock-based version.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-04-07 16:23:08 +02:00

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7.6 KiB
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/*
* Faraday Technology FTTMR010 timer driver
* Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
*
* Based on a rewrite of arch/arm/mach-gemini/timer.c:
* Copyright (C) 2001-2006 Storlink, Corp.
* Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
*/
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/sched_clock.h>
#include <linux/clk.h>
/*
* Register definitions for the timers
*/
#define TIMER1_COUNT (0x00)
#define TIMER1_LOAD (0x04)
#define TIMER1_MATCH1 (0x08)
#define TIMER1_MATCH2 (0x0c)
#define TIMER2_COUNT (0x10)
#define TIMER2_LOAD (0x14)
#define TIMER2_MATCH1 (0x18)
#define TIMER2_MATCH2 (0x1c)
#define TIMER3_COUNT (0x20)
#define TIMER3_LOAD (0x24)
#define TIMER3_MATCH1 (0x28)
#define TIMER3_MATCH2 (0x2c)
#define TIMER_CR (0x30)
#define TIMER_INTR_STATE (0x34)
#define TIMER_INTR_MASK (0x38)
#define TIMER_1_CR_ENABLE (1 << 0)
#define TIMER_1_CR_CLOCK (1 << 1)
#define TIMER_1_CR_INT (1 << 2)
#define TIMER_2_CR_ENABLE (1 << 3)
#define TIMER_2_CR_CLOCK (1 << 4)
#define TIMER_2_CR_INT (1 << 5)
#define TIMER_3_CR_ENABLE (1 << 6)
#define TIMER_3_CR_CLOCK (1 << 7)
#define TIMER_3_CR_INT (1 << 8)
#define TIMER_1_CR_UPDOWN (1 << 9)
#define TIMER_2_CR_UPDOWN (1 << 10)
#define TIMER_3_CR_UPDOWN (1 << 11)
#define TIMER_DEFAULT_FLAGS (TIMER_1_CR_UPDOWN | \
TIMER_3_CR_ENABLE | \
TIMER_3_CR_UPDOWN)
#define TIMER_1_INT_MATCH1 (1 << 0)
#define TIMER_1_INT_MATCH2 (1 << 1)
#define TIMER_1_INT_OVERFLOW (1 << 2)
#define TIMER_2_INT_MATCH1 (1 << 3)
#define TIMER_2_INT_MATCH2 (1 << 4)
#define TIMER_2_INT_OVERFLOW (1 << 5)
#define TIMER_3_INT_MATCH1 (1 << 6)
#define TIMER_3_INT_MATCH2 (1 << 7)
#define TIMER_3_INT_OVERFLOW (1 << 8)
#define TIMER_INT_ALL_MASK 0x1ff
static unsigned int tick_rate;
static void __iomem *base;
static u64 notrace fttmr010_read_sched_clock(void)
{
return readl(base + TIMER3_COUNT);
}
static int fttmr010_timer_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
u32 cr;
/* Setup the match register */
cr = readl(base + TIMER1_COUNT);
writel(cr + cycles, base + TIMER1_MATCH1);
if (readl(base + TIMER1_COUNT) - cr > cycles)
return -ETIME;
return 0;
}
static int fttmr010_timer_shutdown(struct clock_event_device *evt)
{
u32 cr;
/*
* Disable also for oneshot: the set_next() call will arm the timer
* instead.
*/
/* Stop timer and interrupt. */
cr = readl(base + TIMER_CR);
cr &= ~(TIMER_1_CR_ENABLE | TIMER_1_CR_INT);
writel(cr, base + TIMER_CR);
/* Setup counter start from 0 */
writel(0, base + TIMER1_COUNT);
writel(0, base + TIMER1_LOAD);
/* enable interrupt */
cr = readl(base + TIMER_INTR_MASK);
cr &= ~(TIMER_1_INT_OVERFLOW | TIMER_1_INT_MATCH2);
cr |= TIMER_1_INT_MATCH1;
writel(cr, base + TIMER_INTR_MASK);
/* start the timer */
cr = readl(base + TIMER_CR);
cr |= TIMER_1_CR_ENABLE;
writel(cr, base + TIMER_CR);
return 0;
}
static int fttmr010_timer_set_periodic(struct clock_event_device *evt)
{
u32 period = DIV_ROUND_CLOSEST(tick_rate, HZ);
u32 cr;
/* Stop timer and interrupt */
cr = readl(base + TIMER_CR);
cr &= ~(TIMER_1_CR_ENABLE | TIMER_1_CR_INT);
writel(cr, base + TIMER_CR);
/* Setup timer to fire at 1/HT intervals. */
cr = 0xffffffff - (period - 1);
writel(cr, base + TIMER1_COUNT);
writel(cr, base + TIMER1_LOAD);
/* enable interrupt on overflow */
cr = readl(base + TIMER_INTR_MASK);
cr &= ~(TIMER_1_INT_MATCH1 | TIMER_1_INT_MATCH2);
cr |= TIMER_1_INT_OVERFLOW;
writel(cr, base + TIMER_INTR_MASK);
/* Start the timer */
cr = readl(base + TIMER_CR);
cr |= TIMER_1_CR_ENABLE;
cr |= TIMER_1_CR_INT;
writel(cr, base + TIMER_CR);
return 0;
}
/* Use TIMER1 as clock event */
static struct clock_event_device fttmr010_clockevent = {
.name = "TIMER1",
/* Reasonably fast and accurate clock event */
.rating = 300,
.shift = 32,
.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = fttmr010_timer_set_next_event,
.set_state_shutdown = fttmr010_timer_shutdown,
.set_state_periodic = fttmr010_timer_set_periodic,
.set_state_oneshot = fttmr010_timer_shutdown,
.tick_resume = fttmr010_timer_shutdown,
};
/*
* IRQ handler for the timer
*/
static irqreturn_t fttmr010_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &fttmr010_clockevent;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction fttmr010_timer_irq = {
.name = "Faraday FTTMR010 Timer Tick",
.flags = IRQF_TIMER,
.handler = fttmr010_timer_interrupt,
};
static int __init fttmr010_timer_common_init(struct device_node *np)
{
int irq;
base = of_iomap(np, 0);
if (!base) {
pr_err("Can't remap registers");
return -ENXIO;
}
/* IRQ for timer 1 */
irq = irq_of_parse_and_map(np, 0);
if (irq <= 0) {
pr_err("Can't parse IRQ");
return -EINVAL;
}
/*
* Reset the interrupt mask and status
*/
writel(TIMER_INT_ALL_MASK, base + TIMER_INTR_MASK);
writel(0, base + TIMER_INTR_STATE);
writel(TIMER_DEFAULT_FLAGS, base + TIMER_CR);
/*
* Setup free-running clocksource timer (interrupts
* disabled.)
*/
writel(0, base + TIMER3_COUNT);
writel(0, base + TIMER3_LOAD);
writel(0, base + TIMER3_MATCH1);
writel(0, base + TIMER3_MATCH2);
clocksource_mmio_init(base + TIMER3_COUNT,
"fttmr010_clocksource", tick_rate,
300, 32, clocksource_mmio_readl_up);
sched_clock_register(fttmr010_read_sched_clock, 32, tick_rate);
/*
* Setup clockevent timer (interrupt-driven.)
*/
writel(0, base + TIMER1_COUNT);
writel(0, base + TIMER1_LOAD);
writel(0, base + TIMER1_MATCH1);
writel(0, base + TIMER1_MATCH2);
setup_irq(irq, &fttmr010_timer_irq);
fttmr010_clockevent.cpumask = cpumask_of(0);
clockevents_config_and_register(&fttmr010_clockevent, tick_rate,
1, 0xffffffff);
return 0;
}
static int __init fttmr010_timer_of_init(struct device_node *np)
{
/*
* These implementations require a clock reference.
* FIXME: we currently only support clocking using PCLK
* and using EXTCLK is not supported in the driver.
*/
struct clk *clk;
clk = of_clk_get_by_name(np, "PCLK");
if (IS_ERR(clk)) {
pr_err("could not get PCLK");
return PTR_ERR(clk);
}
tick_rate = clk_get_rate(clk);
return fttmr010_timer_common_init(np);
}
CLOCKSOURCE_OF_DECLARE(fttmr010, "faraday,fttmr010", fttmr010_timer_of_init);
/*
* Gemini-specific: relevant registers in the global syscon
*/
#define GLOBAL_STATUS 0x04
#define CPU_AHB_RATIO_MASK (0x3 << 18)
#define CPU_AHB_1_1 (0x0 << 18)
#define CPU_AHB_3_2 (0x1 << 18)
#define CPU_AHB_24_13 (0x2 << 18)
#define CPU_AHB_2_1 (0x3 << 18)
#define REG_TO_AHB_SPEED(reg) ((((reg) >> 15) & 0x7) * 10 + 130)
static int __init gemini_timer_of_init(struct device_node *np)
{
static struct regmap *map;
int ret;
u32 val;
map = syscon_regmap_lookup_by_phandle(np, "syscon");
if (IS_ERR(map)) {
pr_err("Can't get regmap for syscon handle\n");
return -ENODEV;
}
ret = regmap_read(map, GLOBAL_STATUS, &val);
if (ret) {
pr_err("Can't read syscon status register\n");
return -ENXIO;
}
tick_rate = REG_TO_AHB_SPEED(val) * 1000000;
pr_info("Bus: %dMHz ", tick_rate / 1000000);
tick_rate /= 6; /* APB bus run AHB*(1/6) */
switch (val & CPU_AHB_RATIO_MASK) {
case CPU_AHB_1_1:
pr_cont("(1/1)\n");
break;
case CPU_AHB_3_2:
pr_cont("(3/2)\n");
break;
case CPU_AHB_24_13:
pr_cont("(24/13)\n");
break;
case CPU_AHB_2_1:
pr_cont("(2/1)\n");
break;
}
return fttmr010_timer_common_init(np);
}
CLOCKSOURCE_OF_DECLARE(gemini, "cortina,gemini-timer", gemini_timer_of_init);
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