RE: [PATCH 1/1] [ARM] ep93xx clockevent support
From: H Hartley Sweeten
Date: Thu Jul 30 2009 - 18:25:39 EST
On Wednesday, July 22, 2009 3:13 AM, Ahmed Ammar wrote:
> From: Ahmed Ammar <aammar@xxxxxxxxxxxxxxx>
>
> Based on previous work by Thomas Gleixner.
>
> Signed-off-by: Ahmed Ammar <aammar@xxxxxxxxxxxxxxx>
Hmm.. With kernel 2.6.30.2 this does not build. See below.
> ---
> arch/arm/Kconfig | 2 +
> arch/arm/mach-ep93xx/core.c | 130 ++++++++++++++++++-----
> arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h | 6 +
> 3 files changed, 112 insertions(+), 26 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 74713a5..f33fd06 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -273,6 +273,8 @@ config ARCH_EP93XX
> select HAVE_CLK
> select COMMON_CLKDEV
> select ARCH_REQUIRE_GPIOLIB
> + select GENERIC_TIME
> + select GENERIC_CLOCKEVENTS
> 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 7983a3b..cbd9187 100644
> --- a/arch/arm/mach-ep93xx/core.c
> +++ b/arch/arm/mach-ep93xx/core.c
> @@ -33,6 +33,9 @@
> #include <linux/termios.h>
> #include <linux/amba/bus.h>
> #include <linux/amba/serial.h>
> +#include <linux/clocksource.h>
> +#include <linux/clockchips.h>
> +
> #include <linux/io.h>
> #include <linux/i2c.h>
> #include <linux/i2c-gpio.h>
> @@ -100,55 +103,130 @@ void __init ep93xx_map_io(void)
> * to use this timer for something else. We also use timer 4 for keeping
> * track of lost jiffies.
> */
> -static unsigned int last_jiffy_time;
> -
> -#define TIMER4_TICKS_PER_JIFFY ((CLOCK_TICK_RATE + (HZ/2)) / HZ)
>
> static irqreturn_t ep93xx_timer_interrupt(int irq, void *dev_id)
> {
> - __raw_writel(1, EP93XX_TIMER1_CLEAR);
> - 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();
> - }
> -
> + struct clock_event_device *evt = dev_id;
> + __raw_writel(EP93XX_TC_CLEAR, EP93XX_TIMER1_CLEAR);
> + evt->event_handler(evt);
Here I get "error: dereferencing pointer to incomplete type"
> 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_TC123_ENABLE, EP93XX_TIMER1_CONTROL);
> + /* program timer */
> + __raw_writel(evt, EP93XX_TIMER1_LOAD);
> + /* start timer */
> + __raw_writel(tmode | EP93XX_TC123_ENABLE, EP93XX_TIMER1_CONTROL);
> +
> + return 0;
> +}
> +
> +static void ep93xx_set_mode(enum clock_event_mode mode,
> + struct clock_event_device *evt)
> +{
> + u32 tmode = EP93XX_TC123_SEL_508KHZ;
> + /* Disable timer */
> + __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_TC123_PERIODIC;
> +
> + case CLOCK_EVT_MODE_ONESHOT:
> + tmode |= EP93XX_TC123_ENABLE;
> + __raw_writel(tmode, EP93XX_TIMER1_CONTROL);
> + break;
> +
> + case CLOCK_EVT_MODE_SHUTDOWN:
> + case CLOCK_EVT_MODE_UNUSED:
> + case CLOCK_EVT_MODE_RESUME:
> + return;
> + }
> +}
> +
> +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)
> {
> - /* Enable periodic HZ timer. */
> - __raw_writel(0x48, EP93XX_TIMER1_CONTROL);
> - __raw_writel((508469 / HZ) - 1, EP93XX_TIMER1_LOAD);
> - __raw_writel(0xc8, EP93XX_TIMER1_CONTROL);
> + setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq);
> + clockevent_ep93xx.mult = div_sc(508469, NSEC_PER_SEC,
> + clockevent_ep93xx.shift);
> + 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 lost jiffy timer. */
> - __raw_writel(0x100, EP93XX_TIMER4_VALUE_HIGH);
> +/*
> + * 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
> + */
>
> - setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq);
> +cycle_t ep93xx_get_cycles(void)
> +{
> + return __raw_readl(EP93XX_TIMER4_VALUE_LOW);
> }
>
> -static unsigned long ep93xx_gettimeoffset(void)
> +static struct clocksource clocksource_ep93xx = {
> + .name = "ep93xx_timer4",
> + .rating = 200,
> + .read = ep93xx_get_cycles,
Here I get "warning: initialization from incompatible pointer type"
> + .mask = 0xFFFFFFFF,
> + .shift = 20,
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
> +
> +/*
> + * Returns current time from boot in nsecs. It's OK for this to wrap
> + * around for now, as it's just a relative time stamp.
> + */
> +unsigned long long sched_clock(void)
> {
> - int offset;
> + return cyc2ns(&clocksource_ep93xx, ep93xx_get_cycles());
> +}
>
> - offset = __raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time;
> +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);
> + clocksource_register(&clocksource_ep93xx);
> +}
>
> - /* Calculate (1000000 / 983040) * offset. */
> - return offset + (53 * offset / 3072);
> +static void __init ep93xx_timer_init(void)
> +{
> + ep93xx_clocksource_init();
> + ep93xx_clockevent_init();
> }
>
> struct sys_timer ep93xx_timer = {
> - .init = ep93xx_timer_init,
> - .offset = ep93xx_gettimeoffset,
> + .init = ep93xx_timer_init,
> };
>
>
> diff --git a/arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h b/arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h
> index 36c23fb..473cdec 100644
> --- a/arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h
> +++ b/arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h
> @@ -101,6 +101,12 @@
> #define EP93XX_TIMER3_CONTROL EP93XX_TIMER_REG(0x88)
> #define EP93XX_TIMER3_CLEAR EP93XX_TIMER_REG(0x8c)
>
> +#define EP93XX_TC_CLEAR 0x00000001
> +#define EP93XX_TC123_ENABLE 0x00000080
> +#define EP93XX_TC123_PERIODIC 0x00000040
> +#define EP93XX_TC123_SEL_508KHZ 0x00000008
> +#define EP93XX_TC4_ENABLE 0x00000100
> +
> #define EP93XX_I2S_BASE (EP93XX_APB_VIRT_BASE + 0x00020000)
>
> #define EP93XX_SECURITY_BASE (EP93XX_APB_VIRT_BASE + 0x00030000)
--
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