summaryrefslogtreecommitdiff
path: root/arch/arm/mach-ep93xx/timer-ep93xx.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/mach-ep93xx/timer-ep93xx.c')
-rw-r--r--arch/arm/mach-ep93xx/timer-ep93xx.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/arch/arm/mach-ep93xx/timer-ep93xx.c b/arch/arm/mach-ep93xx/timer-ep93xx.c
new file mode 100644
index 000000000000..e5f791145bd0
--- /dev/null
+++ b/arch/arm/mach-ep93xx/timer-ep93xx.c
@@ -0,0 +1,143 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/sched_clock.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <asm/mach/time.h>
+#include "soc.h"
+
+/*************************************************************************
+ * Timer handling for EP93xx
+ *************************************************************************
+ * The ep93xx has four internal timers. Timers 1, 2 (both 16 bit) and
+ * 3 (32 bit) count down at 508 kHz, are self-reloading, and can generate
+ * an interrupt on underflow. Timer 4 (40 bit) counts down at 983.04 kHz,
+ * is free-running, and can't generate interrupts.
+ *
+ * The 508 kHz timers are ideal for use for the timer interrupt, as the
+ * most common values of HZ divide 508 kHz nicely. We pick the 32 bit
+ * timer (timer 3) to get as long sleep intervals as possible when using
+ * CONFIG_NO_HZ.
+ *
+ * The higher clock rate of timer 4 makes it a better choice than the
+ * other timers for use as clock source and for sched_clock(), providing
+ * a stable 40 bit time base.
+ *************************************************************************
+ */
+#define EP93XX_TIMER_REG(x) (EP93XX_TIMER_BASE + (x))
+#define EP93XX_TIMER1_LOAD EP93XX_TIMER_REG(0x00)
+#define EP93XX_TIMER1_VALUE EP93XX_TIMER_REG(0x04)
+#define EP93XX_TIMER1_CONTROL EP93XX_TIMER_REG(0x08)
+#define EP93XX_TIMER123_CONTROL_ENABLE (1 << 7)
+#define EP93XX_TIMER123_CONTROL_MODE (1 << 6)
+#define EP93XX_TIMER123_CONTROL_CLKSEL (1 << 3)
+#define EP93XX_TIMER1_CLEAR EP93XX_TIMER_REG(0x0c)
+#define EP93XX_TIMER2_LOAD EP93XX_TIMER_REG(0x20)
+#define EP93XX_TIMER2_VALUE EP93XX_TIMER_REG(0x24)
+#define EP93XX_TIMER2_CONTROL EP93XX_TIMER_REG(0x28)
+#define EP93XX_TIMER2_CLEAR EP93XX_TIMER_REG(0x2c)
+#define EP93XX_TIMER4_VALUE_LOW EP93XX_TIMER_REG(0x60)
+#define EP93XX_TIMER4_VALUE_HIGH EP93XX_TIMER_REG(0x64)
+#define EP93XX_TIMER4_VALUE_HIGH_ENABLE (1 << 8)
+#define EP93XX_TIMER3_LOAD EP93XX_TIMER_REG(0x80)
+#define EP93XX_TIMER3_VALUE EP93XX_TIMER_REG(0x84)
+#define EP93XX_TIMER3_CONTROL EP93XX_TIMER_REG(0x88)
+#define EP93XX_TIMER3_CLEAR EP93XX_TIMER_REG(0x8c)
+
+#define EP93XX_TIMER123_RATE 508469
+#define EP93XX_TIMER4_RATE 983040
+
+static u64 notrace ep93xx_read_sched_clock(void)
+{
+ u64 ret;
+
+ ret = readl(EP93XX_TIMER4_VALUE_LOW);
+ ret |= ((u64) (readl(EP93XX_TIMER4_VALUE_HIGH) & 0xff) << 32);
+ return ret;
+}
+
+cycle_t ep93xx_clocksource_read(struct clocksource *c)
+{
+ u64 ret;
+
+ ret = readl(EP93XX_TIMER4_VALUE_LOW);
+ ret |= ((u64) (readl(EP93XX_TIMER4_VALUE_HIGH) & 0xff) << 32);
+ return (cycle_t) ret;
+}
+
+static int ep93xx_clkevt_set_next_event(unsigned long next,
+ struct clock_event_device *evt)
+{
+ /* Default mode: periodic, off, 508 kHz */
+ u32 tmode = EP93XX_TIMER123_CONTROL_MODE |
+ EP93XX_TIMER123_CONTROL_CLKSEL;
+
+ /* Clear timer */
+ writel(tmode, EP93XX_TIMER3_CONTROL);
+
+ /* Set next event */
+ writel(next, EP93XX_TIMER3_LOAD);
+ writel(tmode | EP93XX_TIMER123_CONTROL_ENABLE,
+ EP93XX_TIMER3_CONTROL);
+ return 0;
+}
+
+
+static int ep93xx_clkevt_shutdown(struct clock_event_device *evt)
+{
+ /* Disable timer */
+ writel(0, EP93XX_TIMER3_CONTROL);
+
+ return 0;
+}
+
+static struct clock_event_device ep93xx_clockevent = {
+ .name = "timer1",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .set_state_shutdown = ep93xx_clkevt_shutdown,
+ .set_state_oneshot = ep93xx_clkevt_shutdown,
+ .tick_resume = ep93xx_clkevt_shutdown,
+ .set_next_event = ep93xx_clkevt_set_next_event,
+ .rating = 300,
+};
+
+static irqreturn_t ep93xx_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+
+ /* Writing any value clears the timer interrupt */
+ writel(1, EP93XX_TIMER3_CLEAR);
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction ep93xx_timer_irq = {
+ .name = "ep93xx timer",
+ .flags = IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = ep93xx_timer_interrupt,
+ .dev_id = &ep93xx_clockevent,
+};
+
+void __init ep93xx_timer_init(void)
+{
+ /* Enable and register clocksource and sched_clock on timer 4 */
+ writel(EP93XX_TIMER4_VALUE_HIGH_ENABLE,
+ EP93XX_TIMER4_VALUE_HIGH);
+ clocksource_mmio_init(NULL, "timer4",
+ EP93XX_TIMER4_RATE, 200, 40,
+ ep93xx_clocksource_read);
+ sched_clock_register(ep93xx_read_sched_clock, 40,
+ EP93XX_TIMER4_RATE);
+
+ /* Set up clockevent on timer 3 */
+ setup_irq(IRQ_EP93XX_TIMER3, &ep93xx_timer_irq);
+ clockevents_config_and_register(&ep93xx_clockevent,
+ EP93XX_TIMER123_RATE,
+ 1,
+ 0xffffffffU);
+}