[ARM] Orion: system timer support

Signed-off-by: Tzachi Perelstein <tzachi@marvell.com>
Reviewed-by: Nicolas Pitre <nico@marvell.com>
Reviewed-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -338,6 +338,8 @@ config ARCH_ORION
 	depends on MMU
 	select PCI
 	select GENERIC_GPIO
+	select GENERIC_TIME
+	select GENERIC_CLOCKEVENTS
 	help
 	  Support for Marvell Orion System on Chip family.
 

arch/arm/mach-orion/Makefile

@@ -1 +1 @@
-obj-y  += common.o addr-map.o pci.o gpio.o irq.o
+obj-y  += common.o addr-map.o pci.o gpio.o irq.o time.o

arch/arm/mach-orion/common.h

@@ -62,4 +62,9 @@ int orion_pci_hw_wr_conf(u32 bus, u32 dev, u32 func, u32 where, u32 size, u32 va
 void __init orion_gpio_set_valid_pins(u32 pins);
 void gpio_display(void);	/* debug */
 
+/*
+ * Orion system timer (clocksource + clockevnt, /mach-orion/time.c)
+ */
+extern struct sys_timer orion_timer;
+
 #endif /* __ARCH_ORION_COMMON_H__ */

arch/arm/mach-orion/time.c

@@ -0,0 +1,181 @@
+/*
+ * arch/arm/mach-orion/time.c
+ *
+ * Core time functions for Marvell Orion System On Chip
+ *
+ * Maintainer: Tzachi Perelstein <tzachi@marvell.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <asm/mach/time.h>
+#include <asm/arch/orion.h>
+#include "common.h"
+
+/*
+ * Timer0: clock_event_device, Tick.
+ * Timer1: clocksource, Free running.
+ * WatchDog: Not used.
+ *
+ * Timers are counting down.
+ */
+#define CLOCKEVENT	0
+#define CLOCKSOURCE	1
+
+/*
+ * Timers bits
+ */
+#define BRIDGE_INT_TIMER(x)	(1 << ((x) + 1))
+#define TIMER_EN(x)		(1 << ((x) * 2))
+#define TIMER_RELOAD_EN(x)	(1 << (((x) * 2) + 1))
+#define BRIDGE_INT_TIMER_WD	(1 << 3)
+#define TIMER_WD_EN		(1 << 4)
+#define TIMER_WD_RELOAD_EN	(1 << 5)
+
+static cycle_t orion_clksrc_read(void)
+{
+	return (0xffffffff - orion_read(TIMER_VAL(CLOCKSOURCE)));
+}
+
+static struct clocksource orion_clksrc = {
+	.name		= "orion_clocksource",
+	.shift		= 20,
+	.rating		= 300,
+	.read		= orion_clksrc_read,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int
+orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
+{
+	unsigned long flags;
+
+	if (delta == 0)
+		return -ETIME;
+
+	local_irq_save(flags);
+
+	/*
+	 * Clear and enable timer interrupt bit
+	 */
+	orion_write(BRIDGE_CAUSE, ~BRIDGE_INT_TIMER(CLOCKEVENT));
+	orion_setbits(BRIDGE_MASK, BRIDGE_INT_TIMER(CLOCKEVENT));
+
+	/*
+	 * Setup new timer value
+	 */
+	orion_write(TIMER_VAL(CLOCKEVENT), delta);
+
+	/*
+	 * Disable auto reload and kickoff the timer
+	 */
+	orion_clrbits(TIMER_CTRL, TIMER_RELOAD_EN(CLOCKEVENT));
+	orion_setbits(TIMER_CTRL, TIMER_EN(CLOCKEVENT));
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static void
+orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (mode == CLOCK_EVT_MODE_PERIODIC) {
+		/*
+		 * Setup latch cycles in timer and enable reload interrupt.
+		 */
+		orion_write(TIMER_VAL_RELOAD(CLOCKEVENT), LATCH);
+		orion_write(TIMER_VAL(CLOCKEVENT), LATCH);
+		orion_setbits(BRIDGE_MASK, BRIDGE_INT_TIMER(CLOCKEVENT));
+		orion_setbits(TIMER_CTRL, TIMER_RELOAD_EN(CLOCKEVENT) |
+					  TIMER_EN(CLOCKEVENT));
+	} else {
+		/*
+		 * Disable timer and interrupt
+		 */
+		orion_clrbits(BRIDGE_MASK, BRIDGE_INT_TIMER(CLOCKEVENT));
+		orion_write(BRIDGE_CAUSE, ~BRIDGE_INT_TIMER(CLOCKEVENT));
+		orion_clrbits(TIMER_CTRL, TIMER_RELOAD_EN(CLOCKEVENT) |
+					  TIMER_EN(CLOCKEVENT));
+	}
+
+	local_irq_restore(flags);
+}
+
+static struct clock_event_device orion_clkevt = {
+	.name		= "orion_tick",
+	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.shift		= 32,
+	.rating		= 300,
+	.cpumask	= CPU_MASK_CPU0,
+	.set_next_event	= orion_clkevt_next_event,
+	.set_mode	= orion_clkevt_mode,
+};
+
+static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
+{
+	/*
+	 * Clear cause bit and do event
+	 */
+	orion_write(BRIDGE_CAUSE, ~BRIDGE_INT_TIMER(CLOCKEVENT));
+	orion_clkevt.event_handler(&orion_clkevt);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction orion_timer_irq = {
+	.name		= "orion_tick",
+	.flags		= IRQF_DISABLED | IRQF_TIMER,
+	.handler	= orion_timer_interrupt
+};
+
+static void orion_timer_init(void)
+{
+	/*
+	 * Setup clocksource free running timer (no interrupt on reload)
+	 */
+	orion_write(TIMER_VAL(CLOCKSOURCE), 0xffffffff);
+	orion_write(TIMER_VAL_RELOAD(CLOCKSOURCE), 0xffffffff);
+	orion_clrbits(BRIDGE_MASK, BRIDGE_INT_TIMER(CLOCKSOURCE));
+	orion_setbits(TIMER_CTRL, TIMER_RELOAD_EN(CLOCKSOURCE) |
+				  TIMER_EN(CLOCKSOURCE));
+
+	/*
+	 * Register clocksource
+	 */
+	orion_clksrc.mult =
+		clocksource_hz2mult(CLOCK_TICK_RATE, orion_clksrc.shift);
+
+	clocksource_register(&orion_clksrc);
+
+	/*
+	 * Connect and enable tick handler
+	 */
+	setup_irq(IRQ_ORION_BRIDGE, &orion_timer_irq);
+
+	/*
+	 * Register clockevent
+	 */
+	orion_clkevt.mult =
+		div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, orion_clkevt.shift);
+	orion_clkevt.max_delta_ns =
+		clockevent_delta2ns(0xfffffffe, &orion_clkevt);
+	orion_clkevt.min_delta_ns =
+		clockevent_delta2ns(1, &orion_clkevt);
+
+	clockevents_register_device(&orion_clkevt);
+}
+
+struct sys_timer orion_timer = {
+	.init = orion_timer_init,
+};