[PATCH] ARM: ep93xx: clockevent support
Ryan Mallon
rmallon at gmail.com
Tue Aug 7 09:03:40 EDT 2012
On 07/08/12 21:21, Yan Burman wrote:
> ARM: ep93xx: clockevent support
> I have ported to 3.6-rc1 and slightly modified a previous patch for clockevent support for the ep93xx.
> The porting mainly consists of sched_clock support.
> Tested on 9302 based board.
> From: Ahmed Ammar <aammar <at> edge-techno.com>
> Signed-off-by: Yan Burman <burman.yan at gmail.com>
Hi Yan, some comments below.
~Ryan
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index e91c7cd..6dbb828 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -451,7 +451,7 @@ config ARCH_EP93XX
> select CLKDEV_LOOKUP
> select ARCH_REQUIRE_GPIOLIB
> select ARCH_HAS_HOLES_MEMORYMODEL
> - select ARCH_USES_GETTIMEOFFSET
> + select GENERIC_CLOCKEVENTS
> select NEED_MACH_MEMORY_H
> help
> This enables support for the Cirrus EP93xx series of CPUs.
> diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
> index 4afe52a..1497cba 100644
> --- a/arch/arm/mach-ep93xx/core.c
> +++ b/arch/arm/mach-ep93xx/core.c
> @@ -30,6 +30,8 @@
> #include <linux/amba/bus.h>
> #include <linux/amba/serial.h>
> #include <linux/mtd/physmap.h>
> +#include <linux/clocksource.h>
> +#include <linux/clockchips.h>
> #include <linux/i2c.h>
> #include <linux/i2c-gpio.h>
> #include <linux/spi/spi.h>
> @@ -43,6 +45,7 @@
>
> #include <asm/mach/map.h>
> #include <asm/mach/time.h>
> +#include <asm/sched_clock.h>
>
> #include <asm/hardware/vic.h>
>
> @@ -114,63 +117,129 @@ void __init ep93xx_map_io(void)
> #define EP93XX_TIMER4_CLOCK 983040
>
> #define TIMER1_RELOAD ((EP93XX_TIMER123_CLOCK / HZ) - 1)
> -#define TIMER4_TICKS_PER_JIFFY DIV_ROUND_CLOSEST(CLOCK_TICK_RATE, HZ)
> -
> -static unsigned int last_jiffy_time;
>
> static irqreturn_t ep93xx_timer_interrupt(int irq, void *dev_id)
> {
> - /* Writing any value clears the timer interrupt */
> - __raw_writel(1, EP93XX_TIMER1_CLEAR);
> + struct clock_event_device *evt = dev_id;
>
> - /* Recover lost jiffies */
> - while ((signed long)
> - (__raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time)
> - >= TIMER4_TICKS_PER_JIFFY) {
> - last_jiffy_time += TIMER4_TICKS_PER_JIFFY;
> - timer_tick();
> - }
> + __raw_writel(1, EP93XX_TIMER1_CLEAR);
> + evt->event_handler(evt);
>
> return IRQ_HANDLED;
> }
>
> +static int ep93xx_set_next_event(unsigned long evt,
> + struct clock_event_device *unused)
> +{
> + u32 tmode = __raw_readl(EP93XX_TIMER1_CONTROL);
> +
> + /* stop timer */
> + __raw_writel(tmode & ~EP93XX_TIMER123_CONTROL_ENABLE,
> + EP93XX_TIMER1_CONTROL);
> + /* program timer */
> + __raw_writel(evt, EP93XX_TIMER1_LOAD);
> + /* start timer */
> + __raw_writel(tmode | EP93XX_TIMER123_CONTROL_ENABLE,
> + EP93XX_TIMER1_CONTROL);
> +
> + return 0;
> +}
> +
> +static void ep93xx_set_mode(enum clock_event_mode mode,
> + struct clock_event_device *evt)
> +{
> + u32 tmode = EP93XX_TIMER123_CONTROL_CLKSEL;
> + /* Disable timer */
Nitpick - blank line between variable declarations and code.
> + __raw_writel(tmode, EP93XX_TIMER1_CONTROL);
> +
> + switch (mode) {
> + case CLOCK_EVT_MODE_PERIODIC:
> + /* Set timer period */
> + __raw_writel((508469 / HZ) - 1, EP93XX_TIMER1_LOAD);
> + tmode |= EP93XX_TIMER123_CONTROL_MODE;
> +
Is the fall-through here intentional? If so, please put a comment
to indicate that it is.
> + case CLOCK_EVT_MODE_ONESHOT:
> + tmode |= EP93XX_TIMER123_CONTROL_ENABLE;
> + __raw_writel(tmode, EP93XX_TIMER1_CONTROL);
> + break;
> +
> + case CLOCK_EVT_MODE_SHUTDOWN:
> + case CLOCK_EVT_MODE_UNUSED:
> + case CLOCK_EVT_MODE_RESUME:
> + return;
These cases can be removed.
> + }
> +}
> +
> +static struct clock_event_device clockevent_ep93xx = {
> + .name = "ep93xx-timer1",
> + .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
> + .shift = 32,
> + .set_mode = ep93xx_set_mode,
> + .set_next_event = ep93xx_set_next_event,
> +};
> +
> static struct irqaction ep93xx_timer_irq = {
> .name = "ep93xx timer",
> .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
> .handler = ep93xx_timer_interrupt,
> + .dev_id = &clockevent_ep93xx,
> };
>
> -static void __init ep93xx_timer_init(void)
> +static void __init ep93xx_clockevent_init(void)
> {
> - u32 tmode = EP93XX_TIMER123_CONTROL_MODE |
> - EP93XX_TIMER123_CONTROL_CLKSEL;
> + setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq);
> + clockevent_ep93xx.mult = div_sc(508469, NSEC_PER_SEC,
> + clockevent_ep93xx.shift);
core.c has:
#define EP93XX_TIMER123_CLOCK 508469
Maybe we should move that to soc.h so you can use it here.
> + clockevent_ep93xx.max_delta_ns =
> + clockevent_delta2ns(0xfffffffe, &clockevent_ep93xx);
> + clockevent_ep93xx.min_delta_ns =
> + clockevent_delta2ns(0xf, &clockevent_ep93xx);
> + clockevent_ep93xx.cpumask = cpumask_of(0);
> + clockevents_register_device(&clockevent_ep93xx);
> +}
>
> - /* Enable periodic HZ timer. */
> - __raw_writel(tmode, EP93XX_TIMER1_CONTROL);
> - __raw_writel(TIMER1_RELOAD, EP93XX_TIMER1_LOAD);
> - __raw_writel(tmode | EP93XX_TIMER123_CONTROL_ENABLE,
> - EP93XX_TIMER1_CONTROL);
> +/*
> + * timer4 is a 40 Bit timer, separated in a 32bit and a 8 bit
> + * register, EP93XX_TIMER4_VALUE_LOW stores 32 bit word. The
> + * controlregister is in EP93XX_TIMER4_VALUE_HIGH
Missing space between control and register.
> + */
> +static cycle_t ep93xx_get_cycles(struct clocksource *unused)
> +{
> + return __raw_readl(EP93XX_TIMER4_VALUE_LOW);
> +}
>
> - /* Enable lost jiffy timer. */
> - __raw_writel(EP93XX_TIMER4_VALUE_HIGH_ENABLE,
> - EP93XX_TIMER4_VALUE_HIGH);
> +static struct clocksource clocksource_ep93xx = {
> + .name = "ep93xx_timer4",
> + .rating = 200,
> + .read = ep93xx_get_cycles,
> + .mask = 0xFFFFFFFF,
Lower case for hex constant.
> + .shift = 20,
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
>
> - setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq);
> +static void __init ep93xx_clocksource_init(void)
> +{
> + /* Reset time-stamp counter */
> + __raw_writel(0x100, EP93XX_TIMER4_VALUE_HIGH);
> + clocksource_ep93xx.mult =
> + clocksource_hz2mult(983040, clocksource_ep93xx.shift);
core.c has define EP93XX_TIMER4_CLOCK 983040, probably should move
that to soc.h also.
> + clocksource_register(&clocksource_ep93xx);
> }
>
> -static unsigned long ep93xx_gettimeoffset(void)
> +static u32 notrace ep93xx_sched_clock(void)
> {
> - int offset;
> -
> - offset = __raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time;
> + return __raw_readl(EP93XX_TIMER4_VALUE_LOW);
> +}
>
> - /* Calculate (1000000 / 983040) * offset. */
> - return offset + (53 * offset / 3072);
> +static void __init ep93xx_timer_init(void)
> +{
> + ep93xx_clocksource_init();
> + ep93xx_clockevent_init();
> + setup_sched_clock(ep93xx_sched_clock, 32, CLOCK_TICK_RATE);
> }
>
> struct sys_timer ep93xx_timer = {
> .init = ep93xx_timer_init,
> - .offset = ep93xx_gettimeoffset,
> };
>
>
>
>
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