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 0000000000..a9efa7bc2f
--- /dev/null
+++ b/arch/arm/mach-ep93xx/timer-ep93xx.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+#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"
+#include "platform.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;
+}
+
+static u64 ep93xx_clocksource_read(struct clocksource *c)
+{
+	u64 ret;
+
+	ret = readl(EP93XX_TIMER4_VALUE_LOW);
+	ret |= ((u64) (readl(EP93XX_TIMER4_VALUE_HIGH) & 0xff) << 32);
+	return (u64) 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;
+}
+
+void __init ep93xx_timer_init(void)
+{
+	int irq = IRQ_EP93XX_TIMER3;
+	unsigned long flags = IRQF_TIMER | IRQF_IRQPOLL;
+
+	/* 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 */
+	if (request_irq(irq, ep93xx_timer_interrupt, flags, "ep93xx timer",
+			&ep93xx_clockevent))
+		pr_err("Failed to request irq %d (ep93xx timer)\n", irq);
+	clockevents_config_and_register(&ep93xx_clockevent,
+					EP93XX_TIMER123_RATE,
+					1,
+					0xffffffffU);
+}