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linux-next/drivers/clocksource/timer-gemini.c
Linus Walleij 4750535bc9 clocksource/drivers/gemini: Add driver for the Cortina Gemini 
This is a rewrite of the Gemini timer
driver in arch/arm/mach-gemini/timer.c trying to do everything
the device tree way:

- Make every IO-access relative to a base address and dynamic
  so we can do a dynamic ioremap and get going.
- Do not poke around directly in the global syscon registers,
  access them using the syscon regmap style design pattern for
  the one register we need to check.
- Find register range and interrupt from the device tree.

Cc: Janos Laube <janos.dev@gmail.com>
Cc: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-02-07 20:58:30 +01:00

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/*
* Gemini 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>
/*
* 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)
/*
* 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 gemini_read_sched_clock(void)
{
return readl(base + TIMER3_COUNT);
}
static int gemini_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 gemini_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 gemini_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 gemini_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 = gemini_timer_set_next_event,
.set_state_shutdown = gemini_timer_shutdown,
.set_state_periodic = gemini_timer_set_periodic,
.set_state_oneshot = gemini_timer_shutdown,
.tick_resume = gemini_timer_shutdown,
};
/*
* IRQ handler for the timer
*/
static irqreturn_t gemini_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &gemini_clockevent;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction gemini_timer_irq = {
.name = "Gemini Timer Tick",
.flags = IRQF_TIMER,
.handler = gemini_timer_interrupt,
};
static int __init gemini_timer_of_init(struct device_node *np)
{
static struct regmap *map;
int irq;
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");
return -ENODEV;
}
ret = regmap_read(map, GLOBAL_STATUS, &val);
if (ret) {
pr_err("Can't read syscon status register");
return -ENXIO;
}
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;
}
tick_rate = REG_TO_AHB_SPEED(val) * 1000000;
printk(KERN_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:
printk(KERN_CONT "(1/1)\n");
break;
case CPU_AHB_3_2:
printk(KERN_CONT "(3/2)\n");
break;
case CPU_AHB_24_13:
printk(KERN_CONT "(24/13)\n");
break;
case CPU_AHB_2_1:
printk(KERN_CONT "(2/1)\n");
break;
}
/*
* 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,
"gemini_clocksource", tick_rate,
300, 32, clocksource_mmio_readl_up);
sched_clock_register(gemini_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, &gemini_timer_irq);
gemini_clockevent.cpumask = cpumask_of(0);
clockevents_config_and_register(&gemini_clockevent, tick_rate,
1, 0xffffffff);
return 0;
}
CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "cortina,gemini-timer",
gemini_timer_of_init);
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