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Subject[PATCH 1/1] [ARM] ep93xx clockevent support
Date
From: Ahmed Ammar <aammar@edge-techno.com>

Based on previous work by Thomas Gleixner.
---
arch/arm/Kconfig | 3 +
arch/arm/mach-ep93xx/core.c | 129 ++++++++++++++++++-----
arch/arm/mach-ep93xx/include/mach/ep93xx-regs.h | 6 +
arch/arm/mach-ep93xx/include/mach/timex.h | 6 +
4 files changed, 118 insertions(+), 26 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 74713a5..90ffb1d 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.

@@ -849,6 +851,7 @@ config HZ
default AT91_TIMER_HZ if ARCH_AT91
default 100

+
config AEABI
bool "Use the ARM EABI to compile the kernel"
help
diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
index 7983a3b..3357df4 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 +103,129 @@ 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 struct clock_event_device clockevent_ep93xx;

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();
- }
-
+ __raw_writel(EP93XX_TC_CLEAR, EP93XX_TIMER1_CLEAR);
+ clockevent_ep93xx.event_handler(&clockevent_ep93xx);
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,
};

-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,
+ .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)
diff --git a/arch/arm/mach-ep93xx/include/mach/timex.h b/arch/arm/mach-ep93xx/include/mach/timex.h
index 6b3503b..ddf3a8a 100644
--- a/arch/arm/mach-ep93xx/include/mach/timex.h
+++ b/arch/arm/mach-ep93xx/include/mach/timex.h
@@ -1,5 +1,11 @@
/*
* arch/arm/mach-ep93xx/include/mach/timex.h
*/
+#include <mach/ep93xx-regs.h>
+#include <asm/io.h>

#define CLOCK_TICK_RATE 983040
+
+#define mach_read_cycles() __raw_readl(EP93XX_TIMER4_VALUE_LOW)
+#define mach_cycles_to_usecs(d) (((d) * ((1000000LL << 32) / CLOCK_TICK_RATE)) >> 32)
+#define mach_usecs_to_cycles(d) (((d) * (((long long)CLOCK_TICK_RATE << 32) / 1000000)) >> 32)
--
1.6.3.3


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