[ARM] smp: allow re-use of realview localtimer TWD support

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/smp_twd.c

@@ -0,0 +1,173 @@
+/*
+ *  linux/arch/arm/kernel/smp_twd.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+#include <linux/jiffies.h>
+#include <linux/clockchips.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+
+#include <asm/smp_twd.h>
+#include <asm/hardware/gic.h>
+
+#define TWD_TIMER_LOAD 			0x00
+#define TWD_TIMER_COUNTER		0x04
+#define TWD_TIMER_CONTROL		0x08
+#define TWD_TIMER_INTSTAT		0x0C
+
+#define TWD_WDOG_LOAD			0x20
+#define TWD_WDOG_COUNTER		0x24
+#define TWD_WDOG_CONTROL		0x28
+#define TWD_WDOG_INTSTAT		0x2C
+#define TWD_WDOG_RESETSTAT		0x30
+#define TWD_WDOG_DISABLE		0x34
+
+#define TWD_TIMER_CONTROL_ENABLE	(1 << 0)
+#define TWD_TIMER_CONTROL_ONESHOT	(0 << 1)
+#define TWD_TIMER_CONTROL_PERIODIC	(1 << 1)
+#define TWD_TIMER_CONTROL_IT_ENABLE	(1 << 2)
+
+/* set up by the platform code */
+void __iomem *twd_base;
+
+static unsigned long twd_timer_rate;
+
+static void twd_set_mode(enum clock_event_mode mode,
+			struct clock_event_device *clk)
+{
+	unsigned long ctrl;
+
+	switch(mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		/* timer load already set up */
+		ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
+			| TWD_TIMER_CONTROL_PERIODIC;
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		/* period set, and timer enabled in 'next_event' hook */
+		ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	default:
+		ctrl = 0;
+	}
+
+	__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
+}
+
+static int twd_set_next_event(unsigned long evt,
+			struct clock_event_device *unused)
+{
+	unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
+
+	__raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
+	__raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, twd_base + TWD_TIMER_CONTROL);
+
+	return 0;
+}
+
+/*
+ * local_timer_ack: checks for a local timer interrupt.
+ *
+ * If a local timer interrupt has occurred, acknowledge and return 1.
+ * Otherwise, return 0.
+ */
+int twd_timer_ack(void)
+{
+	if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
+		__raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
+		return 1;
+	}
+
+	return 0;
+}
+
+static void __cpuinit twd_calibrate_rate(void)
+{
+	unsigned long load, count;
+	u64 waitjiffies;
+
+	/*
+	 * If this is the first time round, we need to work out how fast
+	 * the timer ticks
+	 */
+	if (twd_timer_rate == 0) {
+		printk("Calibrating local timer... ");
+
+		/* Wait for a tick to start */
+		waitjiffies = get_jiffies_64() + 1;
+
+		while (get_jiffies_64() < waitjiffies)
+			udelay(10);
+
+		/* OK, now the tick has started, let's get the timer going */
+		waitjiffies += 5;
+
+				 /* enable, no interrupt or reload */
+		__raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
+
+				 /* maximum value */
+		__raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
+
+		while (get_jiffies_64() < waitjiffies)
+			udelay(10);
+
+		count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
+
+		twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
+
+		printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
+			(twd_timer_rate / 100000) % 100);
+	}
+
+	load = twd_timer_rate / HZ;
+
+	__raw_writel(load, twd_base + TWD_TIMER_LOAD);
+}
+
+/*
+ * Setup the local clock events for a CPU.
+ */
+void __cpuinit twd_timer_setup(struct clock_event_device *clk)
+{
+	unsigned long flags;
+
+	twd_calibrate_rate();
+
+	clk->name		= "local_timer";
+	clk->features		= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	clk->rating		= 350;
+	clk->set_mode		= twd_set_mode;
+	clk->set_next_event	= twd_set_next_event;
+	clk->shift		= 20;
+	clk->mult		= div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
+	clk->max_delta_ns	= clockevent_delta2ns(0xffffffff, clk);
+	clk->min_delta_ns	= clockevent_delta2ns(0xf, clk);
+
+	/* Make sure our local interrupt controller has this enabled */
+	local_irq_save(flags);
+	get_irq_chip(clk->irq)->unmask(clk->irq);
+	local_irq_restore(flags);
+
+	clockevents_register_device(clk);
+}
+
+/*
+ * take a local timer down
+ */
+void __cpuexit twd_timer_stop(void)
+{
+	__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
+}